REVISING THE HALOFIT MODEL FOR THE NONLINEAR MATTER POWER SPECTRUM
Takahashi, Ryuichi [Faculty of Science and Technology, Hirosaki University, 3 bunkyo-cho, Hirosaki, Aomori 036-8561 (Japan); Sato, Masanori [Department of Physics, Nagoya University, Chikusa, Nagoya 464-8602 (Japan); Nishimichi, Takahiro; Taruya, Atsushi; Oguri, Masamune [Kavli Institute for the Physics and Mathematics of the Universe (Kavli IPMU, WPI), Todai Institutes for Advanced Study, University of Tokyo, Kashiwa, Chiba 277-8583 (Japan)
2012-12-20
Based on a suite of state-of-the-art high-resolution N-body simulations, we revisit the so-called halofit model as an accurate fitting formula for the nonlinear matter power spectrum. While the halofit model has frequently been used as a standard cosmological tool to predict the nonlinear matter power spectrum in a universe dominated by cold dark matter, its precision has been limited by the low resolution of N-body simulations used to determine the fitting parameters, suggesting the necessity of an improved fitting formula at small scales for future cosmological studies. We run high-resolution N-body simulations for 16 cosmological models around the Wilkinson Microwave Anisotropy Probe best-fit cosmological parameters (one-, three-, five-, and seven-year results), including dark energy models with a constant equation of state. The simulation results are used to re-calibrate the fitting parameters of the halofit model so as to reproduce small-scale power spectra of the N-body simulations, while keeping the precision at large scales. The revised fitting formula provides an accurate prediction of the nonlinear matter power spectrum in a wide range of wavenumbers (k {<=} 30 h Mpc{sup -1}) at redshifts 0 {<=} z {<=} 10, with 5% precision for k {<=} 1 h Mpc{sup -1} at 0 {<=} z {<=} 10 and 10% for 1 {<=} k {<=} 10 h Mpc{sup -1} at 0 {<=} z {<=} 3. We discuss the impact of the improved halofit model on weak-lensing power spectra and correlation functions, and show that the improved model better reproduces ray-tracing simulation results.
Testing the Rastall's theory using matter power spectrum
C. E. M. Batista; J. C. Fabris; M. Hamani Daouda
2010-04-26
The Rastall's theory is a modification of the General Relativity theory leading to a different expression for the conservation law in the matter sector compared with the usual one. It has been argued recently that such a theory may have applications to the dark energy problem, since a pressureless fluid may lead to an accelerated universe. In the present work we confront the Rastall's theory with the power spectrum data. The results indicate a configuration that essentially reduces the Rastall's theory to General Relativity, unless the non-usual conservation law refers to a scalar field, situation where other configurations are eventually possible.
Probing the Small Scale Matter Power Spectrum through Dark Matter Annihilation in the Early Universe
Aravind Natarajan; Nick Zhu; Naoki Yoshida
2015-03-11
Recent observations of the cosmic microwave background (CMB) anisotropies and the distribution of galaxies, galaxy clusters, and the Lyman Alpha forest have constrained the shape of the power spectrum of matter fluctuations on large scales k Energy released by dark matter annihilation can modify the spectrum of CMB temperature fluctuations and thus CMB experiments such as Planck have been able to constrain the quantity f /m energy absorbed by gas, is the annihilation rate assumed constant, and m is the particle mass. We assume the standard scale-invariant primordial matter power spectrum of P_prim(k) ~ k^{n_s} at large scales k n_s, the excess small-scale power results in a much larger number of nonlinear small mass halos, particularly at high redshifts. Dark matter annihilation in these halos releases sufficient energy to partially ionize the gas, and consequently modify the spectrum of CMB fluctuations. We show that the recent Planck data can already be used to constrain the power spectrum on small scales. For a simple model with an NFW profile with halo concentration parameter c_200 = 5 and f / m = 1/100 picobarn c / GeV, we can limit the mass variance sigma_{max} < 100 at the 95% confidence level, corresponding to a power law index m_s < 1.43 (1.63) for k_p = 100 (1000) h/Mpc. Our results are also relevant to theories that feature a running spectral index.
Unscreening modified gravity in the matter power spectrum
Lucas Lombriser; Fergus Simpson; Alexander Mead
2015-01-20
Viable modifications of gravity that may produce cosmic acceleration need to be screened in high-density regions such as the Solar System, where general relativity is well tested. Screening mechanisms also prevent strong anomalies in the large-scale structure and limit the constraints that can be inferred on these gravity models from cosmology. We find that by suppressing the contribution of the screened high-density regions in the matter power spectrum, allowing a greater contribution of unscreened low densities, modified gravity models can be more readily discriminated from the concordance cosmology. Moreover, by variation of density thresholds, degeneracies with other effects may be dealt with more adequately. Specializing to chameleon gravity as a worked example for screening in modified gravity, employing N-body simulations of f(R) models and the halo model of chameleon theories, we demonstrate the effectiveness of this method. We find that a percent-level measurement of the clipped power at k Solar System tests or distance indicators in unscreened dwarf galaxies.
Unscreening Modified Gravity in the Matter Power Spectrum
Lucas Lombriser; Fergus Simpson; Alexander Mead
2015-09-21
Viable modifications of gravity that may produce cosmic acceleration need to be screened in high-density regions such as the Solar System, where general relativity is well tested. Screening mechanisms also prevent strong anomalies in the large-scale structure and limit the constraints that can be inferred on these gravity models from cosmology. We find that by suppressing the contribution of the screened high-density regions in the matter power spectrum, allowing a greater contribution of unscreened low densities, modified gravity models can be more readily discriminated from the concordance cosmology. Moreover, by variation of density thresholds, degeneracies with other effects may be dealt with more adequately. Specializing to chameleon gravity as a worked example for screening in modified gravity, employing N-body simulations of f(R) models and the halo model of chameleon theories, we demonstrate the effectiveness of this method. We find that a percent-level measurement of the clipped power at k Solar System tests or distance indicators in unscreened dwarf galaxies. Finally, we verify that our method is also applicable to the Vainshtein mechanism.
Yvonne Y. Y. Wong
2008-10-06
We present the first systematic derivation of the one-loop correction to the large scale matter power spectrum in a mixed cold+hot dark matter cosmology with subdominant massive neutrino hot dark matter. Starting with the equations of motion for the density and velocity fields, we derive perturbative solutions to these quantities and construct recursion relations for the interaction kernels, noting and justifying all approximations along the way. We find interaction kernels similar to those for a cold dark matter-only universe, but with additional dependences on the neutrino energy density fraction f_nu and the linear growth functions of the incoming wavevectors. Compared with the f_nu=0 case, the one-loop corrected matter power spectrum for a mixed dark matter cosmology exhibits a decrease in small scale power exceeding the canonical ~8 f_nu suppression predicted by linear theory, a feature also seen in multi-component N-body simulations.
The implications of the large scale galaxy power spectrum for Cold Dark Matter
C. M. Baugh; E. Gaztanaga
1998-10-12
The APM Galaxy Survey maps the angular positions of more than one million galaxies to $b_{J} = 20$, covering a volume comparable to the forthcoming Sloan Digital Sky Survey. A numerical algorithm has been developed to estimate the power spectrum in three dimensions, using the angular clustering and a model for the redshift distribution of APM Galaxies. The power spectrum obtained is free from distortions of the pattern of clustering caused by the peculiar motions of galaxies. We discuss the uncertainties in the estimated power spectrum and describe tests of the algorithm using large numerical simulations. The APM Galaxy power spectrum shows an inflection at a wavenumber $k \\sim 0.15 h/Mpc$, with evidence for a peak or turnover in the range $ k \\sim 0.03-0.06 h/Mpc$. These features can place strong constraints on Cold Dark Matter models for structure formation.
Heitmann, Katrin; Habib, Salman; Higdon, David; Williams, Brian J; White, Martin; Wagner, Christian
2008-01-01
The power spectrum of density fluctuations is a foundational source of cosmological information. Precision cosmological probes targeted primarily at investigations of dark energy require accurate theoretical determinations of the power spectrum in the nonlinear regime. To exploit the observational power of future cosmological surveys, accuracy demands on the theory are at the one percent level or better. Numerical simulations are currently the only way to produce sufficiently error-controlled predictions for the power spectrum. The very high computational cost of (precision) N-body simulations is a major obstacle to obtaining predictions in the nonlinear regime, while scanning over cosmological parameters. Near-future observations, however, are likely to provide a meaningful constraint only on constant dark energy equation of state 'wCDM' cosmologies. In this paper we demonstrate that a limited set of only 37 cosmological models -- the 'Coyote Universe' suite -- can be used to predict the nonlinear matter power spectrum at the required accuracy over a prior parameter range set by cosmic microwave background observations. This paper is the second in a series of three, with the final aim to provide a high-accuracy prediction scheme for the nonlinear matter power spectrum for wCDM cosmologies.
PkANN: Non-Linear Matter Power Spectrum Interpolation through Artificial Neural Networks
Agarwal, Shankar
2012-12-31
- plotted – with the only difference that on scales k ? 0.085hMpc?1 the N-body spectrum is approximated by the one-Loop standard PT. The stitched spectrum is then sampled at 50 k-values between 0.006hMpc?1 ? k ? 1hMpc?1 and used as Pnl(k, z) for ANN training...-linear regimes, respectively. On smaller scales the matter perturbations have gone non-linear. So, the non-linear matter power spectrum Pnl becomes Pnl(k) = ( (f c + fb) ? P cbnl (k) + f ? ? P ?lin(k) )2 , (2.8) where, P cbnl (k) = (f c + fb)?2 ( f c ? P cnl...
EFFECTS OF THE NEUTRINO MASS SPLITTING ON THE NONLINEAR MATTER POWER SPECTRUM
Wagner, Christian; Verde, Licia; Jimenez, Raul [Institut de Ciencies del Cosmos (ICC), Universitat de Barcelona (IEEC-UB), Marti i Franques 1, E08028 Barcelona (Spain)
2012-06-20
We have performed cosmological N-body simulations which include the effect of the masses of the individual neutrino species. The simulations were aimed at studying the effect of different neutrino hierarchies on the matter power spectrum. Compared to the linear theory predictions, we find that nonlinearities enhance the effect of hierarchy on the matter power spectrum at mildly nonlinear scales. The maximum difference between the different hierarchies is about 0.5% for a sum of neutrino masses of 0.1 eV. Albeit this is a small effect, it is potentially measurable from upcoming surveys. In combination with neutrinoless double-{beta} decay experiments, this opens up the possibility of using the sky to determine if neutrinos are Majorana or Dirac fermions.
Effects of the neutrino mass splitting on the non-linear matter power spectrum
Christian Wagner; Licia Verde; Raul Jimenez
2012-03-23
We have performed cosmological N-body simulations which include the effect of the masses of the individual neutrino species. The simulations were aimed at studying the effect of different neutrino hierarchies on the matter power spectrum. Compared to the linear theory predictions, we find that non-linearities enhance the effect of hierarchy on the matter power spectrum at mildly non-linear scales. The difference between the different hierarchies is about 0.5% for a sum of neutrino masses of 0.1eV. Albeit this is a small effect, it is potentially measurable from upcoming surveys. In combination with neutrinoless double-beta decay experiments, this opens up the possibility of using the sky to determine if neutrinos are Majorana or Dirac fermions.
Calibrating the Nonlinear Matter Power Spectrum: Requirements for Future Weak Lensing Surveys
Dragan Huterer; Masahiro Takada
2005-06-01
Uncertainties in predicting the nonlinear clustering of matter are among the most serious theoretical systematics facing the upcoming wide-field weak gravitational lensing surveys. We estimate the accuracy with which the matter power spectrum will need to be calibrated in order not to contribute appreciably to the error budget for future weak lensing surveys. We consider the random statistical errors and the systematic biases in P(k), as well as some estimates based on current N-body simulations. While the power spectrum on relevant scales (0.1 < k/h Mpc^{-1} < 10) is currently calibrated with N-body simulations to about 5-10%, in the future it will have to be calibrated to about 1-2% accuracy, depending on the specifications of the survey. Encouragingly, we find that even the worst-case error that mimics the effect of cosmological parameters needs to be calibrated to no better than about 0.5-1%. These goals require a suite of high resolution N-body simulations on a relatively fine grid in cosmological parameter space, and should be achievable in the near future.
Zhao, Gong-Bo
2014-04-01
Based on a suite of N-body simulations of the Hu-Sawicki model of f(R) gravity with different sets of model and cosmological parameters, we develop a new fitting formula with a numeric code, MGHalofit, to calculate the nonlinear matter power spectrum P(k) for the Hu-Sawicki model. We compare the MGHalofit predictions at various redshifts (z ? 1) to the f(R) simulations and find that the relative error of the MGHalofit fitting formula of P(k) is no larger than 6% at k ? 1 h Mpc{sup –1} and 12% at k in (1, 10] h Mpc{sup –1}, respectively. Based on a sensitivity study of an ongoing and a future spectroscopic survey, we estimate the detectability of a signal of modified gravity described by the Hu-Sawicki model using the power spectrum up to quasi-nonlinear scales.
Primordial power spectrum from Planck
Dhiraj Kumar Hazra; Arman Shafieloo; Tarun Souradeep
2014-12-18
Using modified Richardson-Lucy algorithm we reconstruct the primordial power spectrum (PPS) from Planck Cosmic Microwave Background (CMB) temperature anisotropy data. In our analysis we use different combinations of angular power spectra from Planck to reconstruct the shape of the primordial power spectrum and locate possible features. Performing an extensive error analysis we found the dip near $\\ell\\sim750-850$ represents the most prominent feature in the data. Feature near $\\ell\\sim1800-2000$ is detectable with high confidence only in 217 GHz spectrum and is apparently consequence of a small systematic as described in the revised Planck 2013 papers. Fixing the background cosmological parameters and the foreground nuisance parameters to their best fit baseline values, we report that the best fit power law primordial power spectrum is consistent with the reconstructed form of the PPS at 2$\\sigma$ C.L. of the estimated errors (apart from the local features mentioned above). As a consistency test, we found the reconstructed primordial power spectrum from Planck temperature data can also substantially improve the fit to WMAP-9 angular power spectrum data (with respect to power-law form of the PPS) allowing an overall amplitude shift of $\\sim2.5\\%$. In this context low-$\\ell$ and 100 GHz spectrum from Planck which have proper overlap in the multipole range with WMAP data found to be completely consistent with WMAP-9 (allowing amplitude shift). As another important result of our analysis we do report the evidence of gravitational lensing through the reconstruction analysis. Finally we present two smooth form of the PPS containing only the important features. These smooth forms of PPS can provide significant improvements in fitting the data (with respect to the power law PPS) and can be helpful to give hints for inflationary model building.
Primordial power spectrum from Planck
Hazra, Dhiraj Kumar; Shafieloo, Arman; Souradeep, Tarun E-mail: arman@apctp.org
2014-11-01
Using modified Richardson-Lucy algorithm we reconstruct the primordial power spectrum (PPS) from Planck Cosmic Microwave Background (CMB) temperature anisotropy data. In our analysis we use different combinations of angular power spectra from Planck to reconstruct the shape of the primordial power spectrum and locate possible features. Performing an extensive error analysis we found the dip near ? ? 750–850 represents the most prominent feature in the data. Feature near ? ? 1800–2000 is detectable with high confidence only in 217 GHz spectrum and is apparently consequence of a small systematic as described in the revised Planck 2013 papers. Fixing the background cosmological parameters and the foreground nuisance parameters to their best fit baseline values, we report that the best fit power law primordial power spectrum is consistent with the reconstructed form of the PPS at 2? C.L. of the estimated errors (apart from the local features mentioned above). As a consistency test, we found the reconstructed primordial power spectrum from Planck temperature data can also substantially improve the fit to WMAP-9 angular power spectrum data (with respect to power-law form of the PPS) allowing an overall amplitude shift of ? 2.5%. In this context low-? and 100 GHz spectrum from Planck which have proper overlap in the multipole range with WMAP data found to be completely consistent with WMAP-9 (allowing amplitude shift). As another important result of our analysis we do report the evidence of gravitational lensing through the reconstruction analysis. Finally we present two smooth form of the PPS containing only the important features. These smooth forms of PPS can provide significant improvements in fitting the data (with respect to the power law PPS) and can be helpful to give hints for inflationary model building.
The tensor bi-spectrum in a matter bounce
Debika Chowdhury; V. Sreenath; L. Sriramkumar
2015-07-28
Matter bounces are bouncing scenarios wherein the universe contracts as in a matter dominated phase at early times. Such scenarios are known to lead to a scale invariant spectrum of tensor perturbations just as de Sitter inflation does. In this work, we examine if the tensor bi-spectrum can discriminate between the inflationary and the bouncing scenarios. Using the Maldacena formalism, we analytically evaluate the tensor bi-spectrum in a matter bounce for an arbitrary triangular configuration of the wavevectors. We show that, over scales of cosmological interest, the non-Gaussianity parameter $h_{_{\\rm NL}}$ that characterizes the amplitude of the tensor bi-spectrum is quite small when compared to the corresponding values in de Sitter inflation. During inflation, the amplitude of the tensor perturbations freeze on super-Hubble scales, a behavior that results in the so-called consistency condition relating the tensor bi-spectrum and the power spectrum in the squeezed limit. In contrast, in the bouncing scenarios, the amplitude of the tensor perturbations grow strongly as one approaches the bounce, which suggests that the consistency condition will not be valid in such situations. We explicitly show that the consistency relation is indeed violated in the matter bounce. We discuss the implications of the results.
The tensor bi-spectrum in a matter bounce
Chowdhury, Debika; Sriramkumar, L
2015-01-01
Matter bounces are bouncing scenarios wherein the universe contracts as in a matter dominated phase at early times. Such scenarios are known to lead to a scale invariant spectrum of tensor perturbations just as de Sitter inflation does. In this work, we examine if the tensor bi-spectrum can discriminate between the inflationary and the bouncing scenarios. Using the Maldacena formalism, we analytically evaluate the tensor bi-spectrum in a matter bounce for an arbitrary triangular configuration of the wavevectors. We show that, over scales of cosmological interest, the non-Gaussianity parameter $h_{_{\\rm NL}}$ that characterizes the amplitude of the tensor bi-spectrum is quite small when compared to the corresponding values in de Sitter inflation. During inflation, the amplitude of the tensor perturbations freeze on super-Hubble scales, a behavior that results in the so-called consistency condition relating the tensor bi-spectrum and the power spectrum in the squeezed limit. In contrast, in the bouncing scenari...
Power Spectrum Analysis of Bursting Cells
Bair, Wyeth
108 Chapter 7 Power Spectrum Analysis of Bursting Cells This chapter contains the text from Bair et) About 33% of the cells have a relatively flat power spectrum with a dip at low temporal frequencies. We. For 93% of cells, the shape of the power spectrum did not change dramatically with stimulus conditions
Dark energy and non-linear power spectrum
Sang Gyu Biern; Jinn-Ouk Gong
2015-06-29
We investigate the effects of homogeneous general dark energy on the non-linear matter perturbation in fully general relativistic context. The equation for the density contrast contains even at linear order new contributions which are non-zero for general dark energy. Taking into account the next-leading-order corrections, we derive the total power spectrum in real and redshift spaces. We find that the observable galaxy power spectrum deviates from the LambdaCDM spectrum, which is nearly identical to that in the Einstein-de Sitter universe, and the relative difference is about 10% on a scale of the baryon acoustic oscillations.
WIMP matter power spectra and small scale power generation
C. Boehm; H. Mathis; J. Devriendt; J. Silk
2003-09-24
Dark Matter (DM) is generally assumed to be massive, cold and collisionless from the structure formation point of view. A more correct statement however is that DM indeed experiences collisional damping, but on a scale which is supposed to be too small to be relevant for structure formation. The aim of this paper is to present a Cold (although ``collisional'') Dark Matter particle whose matter power spectrum is damped and see whether it is distinguishable from standard candidates. To achieve this purpose, we calculate the collisional damping and free-streaming scales of neutralinos and non conventional candidates (say light particles heavier than ~1 MeV but lighter than O(10) GeV). The latter can be considered as Cold Dark Matter (CDM) particles in the sense that they become non relativistic before their thermal decoupling epoch. Unlike neutralinos, however, their linear matter power spectrum can be damped on scales of ~ 10^3 Msol due to their interactions. Since these scales are of cosmological interest for structure formation, we perform a series of numerical simulations to obtain the corresponding non linear matter power spectra P(k)_{nl} at the present epoch. We show that because of small scale regeneration, they all resemble each other at low redshifts, i.e. become very similar to a typical CDM matter power spectrum on all but the smallest scales. Therefore, even if lensing measurements at redshift below unity were to yield a P(k)_{nl} consistent with CDM models, this would not constitute a sufficiently robust evidence in favour of the neutralino to rule out alternative DM candidates.
Power Allocation and Spectrum Sharing in Wireless
Teneketzis, Demosthenis
Power Allocation and Spectrum Sharing in Wireless Networks: An Implementation Theory Approach Ali problems that arise in wireless communication networks. 1.1 Chapter Organization The chapter is organized
A Narrower Spectrum for a Wider View of Matter
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Wider View of Matter July 9, 2014 Bookmark and Share Ultra-high-resolution dispersive optics of the new inelastic x-ray scattering (IXS) spectrometer (top) and IXS spectrum of...
Making waves on CMB power spectrum and inflaton dynamics
Masahiro Kawasaki; Fuminobu Takahashi; Tomo Takahashi
2004-11-11
We discuss cosmic microwave background anisotropies in models with an unconventional primordial power spectrum. In particular, we consider an initial power spectrum with some ``spiky'' corrections. Interestingly, such a primordial power spectrum generates ``wavy'' structure in the CMB angular power spectrum.
Power Spectrum in Krein Space Quantization
M. Mohsenzadeh; S. Rouhani; M. V. Takook
2008-11-06
The power spectrum of scalar field and space-time metric perturbations produced in the process of inflation of universe, have been presented in this paper by an alternative approach to field quantization namely, Krein space quantization [1,2]. Auxiliary negative norm states, the modes of which do not interact with the physical world, have been utilized in this method. Presence of negative norm states play the role of an automatic renormalization device for the theory.
The power spectrum of the circular noise
Daniel Müller
2005-09-30
The circular noise is important in connection to Mach's principle, and also as a possible probe of the Unruh effect. In this letter the power spectrum of the detector following the Trocheries-Takeno motion in the Minkowski vacuum is analytically obtained in the form of an infinite series. A mean distribution function and corresponding energy density are obtained for this particular detected noise. The analogous of a non constant temperature distribution is obtained. And in the end, a brief discussion about the equilibrium configuration is given.
Smoothing spline primordial power spectrum reconstruction
Carolyn Sealfon; Licia Verde; Raul Jimenez
2005-11-01
We reconstruct the shape of the primordial power spectrum (PPS) using a smoothing spline. Our adapted smoothing spline technique provides a complementary method to existing efforts to search for smooth features in the PPS, such as a running spectral index. With this technique we find no significant indication with WMAP first-year data that the PPS deviates from Harrison-Zeldovich and no evidence for loss of power on large scales. We also examine the effect on the cosmological parameters of the additional PPS freedom. Smooth variations in the PPS are not significantly degenerate with other cosmological parameters, but the spline reconstruction greatly increases the errors on the optical depth and baryon fraction.
Contribution of domain wall networks to the CMB power spectrum
Lazanu, A; Shellard, E P S
2015-01-01
We use three domain wall simulations from the radiation era to the late time dark energy domination era based on the PRS algorithm to calculate the energy-momentum tensor components of domain wall networks in an expanding universe. Unequal time correlators in the radiation, matter and cosmological constant epochs are calculated using the scaling regime of each of the simulations. The CMB power spectrum of a network of domain walls is determined. The first ever quantitative constraint for the domain wall surface tension is obtained using a Markov chain Monte Carlo method; an energy scale of domain walls of 0.93 MeV, which is close but below the Zel'dovich bound, is determined.
Just enough inflation: power spectrum modifications at large scales
Cicoli, Michele [Dipartimento di Fisica ed Astronomia, Universitŕ di Bologna, via Irnerio 46, 40126 Bologna (Italy); Downes, Sean [Leung Center for Cosmology and Particle Astrophysics, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan (China); Dutta, Bhaskar [Mitchell Institute for Fundamental Physics and Astronomy, Department of Physics and Astronomy, Texas A and M University, College Station, TX 77843-4242 (United States); Pedro, Francisco G.; Westphal, Alexander, E-mail: mcicoli@ictp.it, E-mail: ssdownes@phys.ntu.edu.tw, E-mail: dutta@physics.tamu.edu, E-mail: francisco.pedro@desy.de, E-mail: alexander.westphal@desy.de [Deutsches Elektronen-Synchrotron DESY, Theory Group, D-22603 Hamburg (Germany)
2014-12-01
We show that models of 'just enough' inflation, where the slow-roll evolution lasted only 50- 60 e-foldings, feature modifications of the CMB power spectrum at large angular scales. We perform a systematic analytic analysis in the limit of a sudden transition between any possible non-slow-roll background evolution and the final stage of slow-roll inflation. We find a high degree of universality since most common backgrounds like fast-roll evolution, matter or radiation-dominance give rise to a power loss at large angular scales and a peak together with an oscillatory behaviour at scales around the value of the Hubble parameter at the beginning of slow-roll inflation. Depending on the value of the equation of state parameter, different pre-inflationary epochs lead instead to an enhancement of power at low ?, and so seem disfavoured by recent observational hints for a lack of CMB power at ??< 40. We also comment on the importance of initial conditions and the possibility to have multiple pre-inflationary stages.
Power spectrum of electron number density perturbations at cosmological recombination epoch
B. Venhlovska; B. Novosyadlyj
2009-02-19
The power spectrum of number density perturbations of free electrons is obtained for the epoch of cosmological recombination of hydrogen. It is shown that amplitude of the electron perturbations power spectrum of scales larger than acoustic horizon exceeds by factor of 17 the amplitude of baryon matter density ones (atoms and ions of hydrogen and helium). In the range of the first and second acoustic peaks such relation is 18, in the range of the third one 16. The dependence of such relations on cosmological parameters is analysed too.
MEASURING THE JET POWER OF FLAT-SPECTRUM RADIO QUASARS
Shabala, S. S.; Santoso, J. S.; Godfrey, L. E. H.
2012-09-10
We use frequency-dependent position shifts of flat-spectrum radio cores to estimate the kinetic power of active galactic nucleus (AGN) jets. We find a correlation between the derived jet powers and AGN narrow-line luminosity, consistent with the well-known relation for radio galaxies and steep spectrum quasars. This technique can be applied to intrinsically weak jets even at high redshift.
Cosmology Constraints from the Weak Lensing Peak Counts and the Power Spectrum in CFHTLenS
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Liu, Jia; May, Morgan; Petri, Andrea; Haiman, Zoltan; Hui, Lam; Kratochvil, Jan M.
2015-03-04
Lensing peaks have been proposed as a useful statistic, containing cosmological information from non-Gaussianities that is inaccessible from traditional two-point statistics such as the power spectrum or two-point correlation functions. Here we examine constraints on cosmological parameters from weak lensing peak counts, using the publicly available data from the 154 deg2 CFHTLenS survey. We utilize a new suite of ray-tracing N-body simulations on a grid of 91 cosmological models, covering broad ranges of the three parameters ?m, ?8, and w, and replicating the galaxy sky positions, redshifts, and shape noise in the CFHTLenS observations. We then build an emulator thatmore »interpolates the power spectrum and the peak counts to an accuracy of ? 5%, and compute the likelihood in the three-dimensional parameter space (?m, ?8, w) from both observables. We find that constraints from peak counts are comparable to those from the power spectrum, and somewhat tighter when different smoothing scales are combined. Neither observable can constrain w without external data. When the power spectrum and peak counts are combined, the area of the error “banana” in the (?m, ?8) plane reduces by a factor of ? two, compared to using the power spectrum alone. For a flat ? cold dark matter model, combining both statistics, we obtain the constraint ?8(?m/0.27)0.63 = 0.85+0.03-0.03.« less
Cosmology Constraints from the Weak Lensing Peak Counts and the Power Spectrum in CFHTLenS
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Liu, Jia [Department of Astronomy and Astrophysics, Columbia University, New York, NY, (United States); May, Morgan [Physics Department, Brookhaven National Laboratory, Upton, NY, (United States); Petri, Andrea [Department of Physics, Columbia University, New York, NY, (United States); Haiman, Zoltan [Department of Astronomy and Astrophysics, Columbia University, New York, NY, (United States); Institute for Strings, Cosmology, and Astroparticle Physics (ISCAP), Columbia University, New York, (United States); Hui, Lam [Department of Physics, Columbia University, New York, NY, (United States); Institute for Strings, Cosmology, and Astroparticle Physics (ISCAP), Columbia University, New York, (United States); Kratochvil, Jan M. [Astrophysics and Cosmology Research Unit, University of KwaZulu-Natal, Westville, Durban, (South Africa)
2015-03-01
Lensing peaks have been proposed as a useful statistic, containing cosmological information from non-Gaussianities that is inaccessible from traditional two-point statistics such as the power spectrum or two-point correlation functions. Here we examine constraints on cosmological parameters from weak lensing peak counts, using the publicly available data from the 154 deg2 CFHTLenS survey. We utilize a new suite of ray-tracing N-body simulations on a grid of 91 cosmological models, covering broad ranges of the three parameters ?m, ?8, and w, and replicating the galaxy sky positions, redshifts, and shape noise in the CFHTLenS observations. We then build an emulator that interpolates the power spectrum and the peak counts to an accuracy of ? 5%, and compute the likelihood in the three-dimensional parameter space (?m, ?8, w) from both observables. We find that constraints from peak counts are comparable to those from the power spectrum, and somewhat tighter when different smoothing scales are combined. Neither observable can constrain w without external data. When the power spectrum and peak counts are combined, the area of the error “banana” in the (?m, ?8) plane reduces by a factor of ? two, compared to using the power spectrum alone. For a flat ? cold dark matter model, combining both statistics, we obtain the constraint ?8(?m/0.27)0.63 = 0.85+0.03-0.03.
On the Power Spectrum Density of Gamma Ray Bursts
Motoko Suzuki; Masahiro Morikawa; Izumi Joichi
2001-04-13
Gamma ray bursts (GRBs) are known to have short-time variability and power-law behavior with the index -1.67 in the power spectrum density. Reanalyzing the expanded data, we have found a) the power-law comes from the global profile of the burst and not from the self-similar shots nor rapid fluctuations in the luminosity profile. b) The power indices vary from burst to burst and the value -1.67 is given simply as the mean value of the distribution; there is no systematic correlation among GRBs to yield the power law.
Effects of halo substructure on the power spectrum and bispectrum
Derek Dolney; Bhuvnesh Jain; Masahiro Takada
2004-09-22
We study the effects of halo substructure and a distribution in the concentration parameter of haloes on large-scale structure statistics. The effects on the power spectrum and bispectrum are studied on the smallest scales accessible from future surveys. We compare halo-model predictions with results based on N-body simulations, but also extend our predictions to 10-kpc scales which will be probed by future simulations. We find that weak-lensing surveys proposed for the coming decade can probe the power spectrum on small enough scales to detect substructure in massive haloes. We discuss the prospects of constraining the mass fraction in substructure in view of partial degeneracies with parameters such as the tilt and running of the primordial power spectrum.
Quantifying galactic propagation uncertainty in WIMP dark matter search with AMS01 Z=-1 spectrum
Xiao, Sa, Ph. D. Massachusetts Institute of Technology
2009-01-01
A search for a WIMP dark matter annihilation signal is carried out in the AMS01 negatively charged (Z=-I) particle spectrum, following a set of supersymmetric benchmark scenarios in the mSUGRA framework. The result is ...
SIC (MUltiple SIgnal Classification) CSP (Cross-power Spectrum Phase)
Takiguchi, Tetsuya
2ch CSP ( ) 1 MU- SIC (MUltiple SIgnal Classification) CSP (Cross- power Spectrum Phase) [1, 2, 3, 4] [5, 6] [7, 8, 9, 10] [7] CSP CSP [8] [9] CSP [10] Estimation of talker's head orientation based (Kobe univ.) [11] 2ch CSP CSP CSP CSP 2 CSP GCC-PHAT (Generalized Cross- Correlation PHAse Transform
Power spectrum of post-inflationary primordial magnetic fields
Hector J. Hortua; Leonardo Castańeda
2014-12-16
The origin of large scale magnetic fields is one of the most puzzling topics in cosmology and astrophysics. It is assumed that the observed magnetic fields result from the amplification of an initial field produced in the early universe. In this paper we compute the exact power spectrum of magnetic fields created after inflation best known as post inflationary magnetic fields, using the first order cosmological perturbation theory. Our treatment differs from others works because we include an infrared cutoff which encodes only causal modes in the spectrum. The cross-correlation between magnetic energy density with Lorentz force and the anisotropic part of the electromagnetic field are exactly computed. We compare our results with previous works finding agreement in cases where the ratio between lower and upper cutoff is very small. However, we found that spectrum is strongly affected when this ratio is greater than 0.2. Moreover, the effect of a post inflationary magnetic field with a lower cutoff on the angular power spectrum in the temperature distribution of CMB was also exactly calculated. The main feature is a shift of the spectrum's peak as function of the infrared cutoff, therefore analyzing this effect we could infer the value of this cutoff and thus constraining the primordial magnetic fields generation models.
Supernova neutrinos: Earth matter effects and neutrino mass spectrum
C. Lunardini; A. Yu. Smirnov
2001-06-29
We perform a detailed study of the Earth matter effects on supernova neutrinos. The dependences of these effects on the properties of the original neutrino fluxes, on the trajectory of the neutrinos inside the Earth and on the oscillation parameters are described. We show that, for a large fraction (60 %) of the possible arrival times of the signal, the neutrino flux crosses a substantial amount of the matter of the Earth at least for one of the existing detectors. For oscillation parameters from the LMA solution of the solar neutrino problem the Earth matter effect consists in an oscillatory modulation of the $\\barnue$ and/or $\
Cosmological parameters from lensing power spectrum and bispectrum tomography
Masahiro Takada; Bhuvnesh Jain
2005-07-20
We examine how lensing tomography with the bispectrum and power spectrum can constrain cosmological parameters and the equation of state of dark energy. Our analysis uses the full information at the two- and three-point level from angular scales of a few degrees to 5 arcminutes (50 < l < 3000), which will be probed by lensing surveys. We use all triangle configurations, cross-power spectra and bispectra constructed from up to three redshift bins with photometric redshifts, and relevant covariances in our analysis. We find that the parameter constraints from bispectrum tomography are comparable to those from power spectrum tomography. Combining the two improves parameter accuracies by a factor of three due to their complementarity. For the dark energy parameterization w(a) = w0 + wa(1-a), the marginalized errors from lensing alone are sigma(w0) = 0.03 fsky^{-1/2} and sigma(wa) = 0.1 fsky^{-1/2}. We show that these constraints can be further improved when combined with measurements of the cosmic microwave background or Type Ia supernovae. The amplitude and shape of the mass power spectrum are also shown to be precisely constrained. We use hyper-extended perturbation theory to compute the nonlinear lensing bispectrum for dark energy models. Accurate model predictions of the bispectrum in the moderately nonlinear regime, calibrated with numerical simulations, will be needed to realize the parameter accuracy we have estimated. Finally, we estimate how well the lensing bispectrum can constrain a model with primordial non-Gaussianity.
Analyzing the Power Spectrum of the Little Bangs
Agnes Mocsy; Paul Sorensen
2011-01-10
In this talk we discuss the analogy between data from heavy-ion collisions and the Cosmic Microwave Background. We identify p_T correlations data as the heavy-ion analogy to the CMB and extract a power-spectrum from the heavy-ion data. We define the ratio of the final state power-spectrum to the initial coordinate-space eccentricity as the transfer-function. From the transfer-function we find that higher $n$ terms are suppressed and we argue that the suppression provides information on length scales like the mean-free-path. We make a rough estimate of the mean-free-path and find that it is larger than estimates based on the centrality dependence of v_2.
Single-Particle Spectrum of Pure Neutron Matter
Khalaf Gad; Hesham Mansour
2015-02-06
We have calculated the self-consistent auxiliary potential effects on the binding energy of neutron matter using the Brueckner Hartree Fock approach by adopting the Argonne V18 and CD-Bonn potentials. The binding energy with the four different choices for the self-consistent auxiliary potential is discussed. Also, the binding energy of neutron matter has been computed within the framework of the self-consistent Green s function approach. We also compare the binding energies obtained in this study with those obtained by various microscopic approaches.
CMB anisotropy power spectrum using linear combinations of WMAP maps Rajib Saha,1,2,3
Souradeep, Tarun
CMB anisotropy power spectrum using linear combinations of WMAP maps Rajib Saha,1,2,3 Simon Prunet year WMAP data by Saha et al. 2006. All previous estimates of the power spectrum of the CMB are based
PRODUCT OF POWER SPECTRUM AND GROUP DELAY FUNCTION FOR SPEECH RECOGNITION
PRODUCT OF POWER SPECTRUM AND GROUP DELAY FUNCTION FOR SPEECH RECOGNITION Donglai Zhu and Kuldip K by Murthy and Gadde [6] for speech recognition. In this paper, we propose to use the product of the power. In this paper, we define the product spectrum as the product of the power spectrum and the GDF. It combines
R. Angulo; C. M. Baugh; C. S. Frenk; R. G. Bower; A. Jenkins; S. L. Morris
2005-06-13
Acoustic oscillations in the baryon-photon fluid leave a signature in the matter power spectrum. The overall shape of the spectrum and the wavelength of the oscillations depend upon the sound horizon scale at recombination. Using the $\\Lambda$ cold dark matter Hubble Volume simulation, we show that the imprint of baryons is visible in the power spectrum of cluster-mass dark matter haloes, in spite of significant differences between the halo power spectrum and the prediction of linear perturbation theory. A measurement of the sound horizon scale can constrain the dark energy equation of state. We show that a survey of clusters at intermediate redshift ($ z\\sim1 $), like the Sunyaev-Zeldovich survey proposed by the South Pole Telescope or a red sequence photometric survey with VISTA, could potentially constrain the sound horizon scale to an accuracy of $\\sim 2%$, in turn fixing the ratio of the pressure of the dark energy to its density ($w$) to better than $\\sim 10%$. Our approach does not require knowledge of the cluster mass, unlike those that depend upon the abundance of clusters.
Primordial power spectrum of tensor perturbations in Finsler spacetime
Xin Li; Sai Wang
2015-08-16
We first investigate the gravitational wave in the flat Finsler spacetime. In the Finslerian universe, we derive the perturbed gravitational field equation with tensor perturbations. The Finslerian background spacetime breaks rotational symmetry and induces parity violation. Then we obtain the modified primordial power spectrum of tensor perturbations. The parity violation feature requires that the anisotropic effect contributes to $TT,TE,EE,BB$ angular correlation coefficients with $l'=l+1$ and $TB,EB$ with $l'=l$. The numerical results show that the anisotropic contributions to angular correlation coefficients depend on $m$, and $TE$ and $ET$ angular correlation coefficients are different.
Higher derivatives and power spectrum in effective single field inflation
Jinn-Ouk Gong; Min-Seok Seo; Spyros Sypsas
2015-03-10
We study next-to-leading corrections to the effective action of the curvature perturbation obtained by integrating out the coupled heavy isocurvature perturbation. These corrections result from including higher order derivative operators, weighted by the mass scale of the heavy physics, in the effective theory expansion. We find that the correction terms are suppressed by the ratio of the Hubble parameter to the heavy mass scale. The corresponding corrections to the power spectrum of the curvature perturbation are presented for a simple illustrative example.
M. Sereno; J. A. Peacock
2006-05-19
Deviations from the gravitational inverse-square law would imprint scale-dependent features on the power spectrum of mass density fluctuations. We model such deviations as a Yukawa-like contribution to the gravitational potential and discuss the growth function in a mixed dark matter model with adiabatic initial conditions. Evolution of perturbations is considered in general non-flat cosmological models with a cosmological constant, and an analytical approximation for the growth function is provided. The coupling between baryons and cold dark matter across recombination is negligibly affected by modified gravity physics if the proper cutoff length of the long-range Yukawa-like force is > 10 h^{-1} Mpc. Enhancement of gravity affects the subsequent evolution, boosting large-scale power in a way that resembles the effect of a lower matter density. This phenomenon is almost perfectly degenerate in power-spectrum shape with the effect of a background of massive neutrinos. Back-reaction on density growth from a modified cosmic expansion rate should however also affect the normalization of the power spectrum, with a shape distortion similar to the case of a non-modified background.
Power spectrum for inflation models with quantum and thermal noises
Rudnei O. Ramos; L. A. da Silva
2013-03-25
We determine the power spectrum for inflation models covering all regimes from cold (isentropic) to warm (nonisentropic) inflation. We work in the context of the stochastic inflation approach, which can nicely describe both types of inflationary regimes concomitantly. A throughout analysis is carried out to determine the allowed parameter space for simple single field polynomial chaotic inflation models that is consistent with the most recent cosmological data from the nine-year Wilkinson Microwave Anisotropy Probe (WMAP) and in conjunction with other observational cosmological sources. We present the results for both the amplitude of the power spectrum, the spectral index and for the tensor to scalar curvature perturbation amplitude ratio. We briefly discuss cases when running is present. Despite single field polynomial-type inflaton potential models be strongly disfavored, or even be already ruled out in their simplest versions in the case of cold inflation, this is not the case for nonisentropic inflation models in general (warm inflation in particular), though higher order polynomial potentials (higher than quartic order) tend to become less favorable also in this case, presenting a much smaller region of parameter space compatible with the recent observational cosmological data. Our findings also remain valid in face of the recently released Planck results.
Power spectrum and non-Gaussianities in anisotropic inflation
Dey, Anindya; Kovetz, Ely D.; Paban, Sonia E-mail: elykovetz@gmail.com
2014-06-01
We study the planar regime of curvature perturbations for single field inflationary models in an axially symmetric Bianchi I background. In a theory with standard scalar field action, the power spectrum for such modes has a pole as the planarity parameter goes to zero. We show that constraints from back reaction lead to a strong lower bound on the planarity parameter for high-momentum planar modes and use this bound to calculate the signal-to-noise ratio of the anisotropic power spectrum in the CMB, which in turn places an upper bound on the Hubble scale during inflation allowed in our model. We find that non-Gaussianities for these planar modes are enhanced for the flattened triangle and the squeezed triangle configurations, but show that the estimated values of the f{sub NL} parameters remain well below the experimental bounds from the CMB for generic planar modes (other, more promising signatures are also discussed). For a standard action, f{sub NL} from the squeezed configuration turns out to be larger compared to that from the flattened triangle configuration in the planar regime. However, in a theory with higher derivative operators, non-Gaussianities from the flattened triangle can become larger than the squeezed configuration in a certain limit of the planarity parameter.
Power spectrum for inflation models with quantum and thermal noises
Ramos, Rudnei O.; Silva, L.A. da, E-mail: rudnei@uerj.br, E-mail: las.leandro@gmail.com [Departamento de Física Teórica, Universidade do Estado do Rio de Janeiro, 20550-013 Rio de Janeiro, RJ (Brazil)
2013-03-01
We determine the power spectrum for inflation models covering all regimes from cold (isentropic) to warm (nonisentropic) inflation. We work in the context of the stochastic inflation approach, which can nicely describe both types of inflationary regimes concomitantly. A throughout analysis is carried out to determine the allowed parameter space for simple single field polynomial chaotic inflation models that is consistent with the most recent cosmological data from the nine-year Wilkinson Microwave Anisotropy Probe (WMAP) and in conjunction with other observational cosmological sources. We present the results for both the amplitude of the power spectrum, the spectral index and for the tensor to scalar curvature perturbation amplitude ratio. We briefly discuss cases when running is present. Despite single field polynomial-type inflaton potential models be strongly disfavored, or even be already ruled out in their simplest versions in the case of cold inflation, this is not the case for nonisentropic inflation models in general (warm inflation in particular), though higher order polynomial potentials (higher than quartic order) tend to become less favorable also in this case, presenting a much smaller region of parameter space compatible with the recent observational cosmological data.
Using the Comoving Maximum of the Galaxy Power Spectrum to Measure Cosmological Curvature
Tom Broadhurst; Andrew H. Jaffe
1999-04-26
The large-scale maximum at k~0.05 identified in the power-spectrum of galaxy fluctuations provides a co-moving scale for measuring cosmological curvature. In shallow 3D surveys the peak is broad, but appears to be well resolved in 1D, at ~130 Mpc (k=0.048), comprising evenly spaced peaks and troughs. Surprisingly similar behaviour is evident at z=3 in the distribution of Lyman-break galaxies, for which we find a 5 sigma excess of pairs separated by Delta z=0.22pm0.02, equivalent to 85Mpc for Omega=1, increasing to 170 Mpc for Omega=0, with a number density contrast of 30% averaged over 5 independent fields. The combination, 3.2\\Omega_m -\\Omega_{\\Lambda}=0.7, matches the local scale of 130 Mpc, i.e. Omega=0.2\\pm0.1 or Omega_{m}=0.4\\pm0.1 for the matter-dominated and flat models respectively, with an uncertainty given by the width of the excess correlation. The consistency here of the flat model with SNIa based claims is encouraging, but overshadowed by the high degree of coherence observed in 1D compared with conventional Gaussian models of structure formation. The appearance of this scale at high redshift and its local prominence in the distribution of Abell clusters lends support to claims that the high-z `spikes' represent young clusters. Finally we show that a spike in the primordial power spectrum of delta\\rho/\\rho=0.3 at k=0.05 has little effect on the CMB, except to exaggerate the first Doppler peak in flat matter-dominated models, consistent with recent observations. \\\\effect on the CMB, except to exaggerate the first Doppler peak in flat matter-dominated models, consistent with recent observations.
Precision Determination Of The Nonlinear Matter Power Spectrum (Journal
Office of Scientific and Technical Information (OSTI)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfateSciTech ConnectSpeeding accessusers'(xâ‰¤2) surface: A combined scanningusingArticle)
Precision Determination Of The Nonlinear Matter Power Spectrum (Journal
Office of Scientific and Technical Information (OSTI)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfateSciTech ConnectSpeeding accessusers'(xâ‰¤2) surface: A combined scanningusingArticle)Article)
THE EFFECT OF A REFRACTORY PERIOD ON THE POWER SPECTRUM OF NEURONAL DISCHARGE
Bair, Wyeth
produce peaks in the power spectrum near 40 Hz. Key words. neuronal spike trains, refractory periodTHE EFFECT OF A REFRACTORY PERIOD ON THE POWER SPECTRUM OF NEURONAL DISCHARGE JOEL FRANKLIN neuron refractory period and a statistically independent interval due to a stationary external process
What is the spectrum of cold dark matter particles on Earth?
Pierre Sikivie
1996-06-24
It is argued that the spectrum of cold dark matter particles on Earth has peaks in velocity space associated with particles falling onto the Galaxy for the first time and with particles which have fallen in and out of the Galaxy only a small number of times in the past. Estimates are given for the sizes and velocity magnitudes of the first few peaks. The estimates are based upon the secondary infall model of halo formation which has been generalized to include the effect of angular momentum.
The Knotted Sky I: Planck constraints on the primordial power spectrum
Aslanyan, Grigor; Price, Layne C.; Easther, Richard [Department of Physics, University of Auckland, Private Bag 92019, Auckland (New Zealand); Abazajian, Kevork N., E-mail: g.aslanyan@auckland.ac.nz, E-mail: lpri691@aucklanduni.ac.nz, E-mail: kevork@uci.edu, E-mail: r.easther@auckland.ac.nz [Department of Physics, University of California at Irvine, Irvine, CA 92697 (United States)
2014-08-01
Using the temperature data from Planck we search for departures from a power-law primordial power spectrum, employing Bayesian model-selection and posterior probabilities. We parametrize the spectrum with n knots located at arbitrary values of logk, with both linear and cubic splines. This formulation recovers both slow modulations and sharp transitions in the primordial spectrum. The power spectrum is well-fit by a featureless, power-law at wavenumbers k>10{sup -3} Mpc{sup -1}. A modulated primordial spectrum yields a better fit relative to ?CDM at large scales, but there is no strong evidence for a departure from a power-law spectrum. Moreover, using simulated maps we show that a local feature at k ? 10{sup -3} Mpc{sup -1} can mimic the suppression of large-scale power. With multi-knot spectra we see only small changes in the posterior distributions for the other free parameters in the standard ?CDM universe. Lastly, we investigate whether the hemispherical power asymmetry is explained by independent features in the primordial power spectrum in each ecliptic hemisphere, but find no significant differences between them.
Reconstruction of the primordial power spectrum of curvature perturbations using multiple data sets
Hunt, Paul; Sarkar, Subir E-mail: s.sarkar@physics.ox.ac.uk
2014-01-01
Detailed knowledge of the primordial power spectrum of curvature perturbations is essential both in order to elucidate the physical mechanism ('inflation') which generated it, and for estimating the cosmological parameters from observations of the cosmic microwave background and large-scale structure. Hence it ought to be extracted from such data in a model-independent manner, however this is difficult because relevant cosmological observables are given by a convolution of the primordial perturbations with some smoothing kernel which depends on both the assumed world model and the matter content of the universe. Moreover the deconvolution problem is ill-conditioned so a regularisation scheme must be employed to control error propagation. We demonstrate that 'Tikhonov regularisation' can robustly reconstruct the primordial spectrum from multiple cosmological data sets, a significant advantage being that both its uncertainty and resolution are then quantified. Using Monte Carlo simulations we investigate several regularisation parameter selection methods and find that generalised cross-validation and Mallow's C{sub p} method give optimal results. We apply our inversion procedure to data from the Wilkinson Microwave Anisotropy Probe, other ground-based small angular scale CMB experiments, and the Sloan Digital Sky Survey. The reconstructed spectrum (assuming the standard ?CDM cosmology) is not scale-free but has an infrared cutoff at k?<5 × 10{sup ?4} Mpc{sup ?1} (due to the anomalously low CMB quadrupole) and several features with ? 2? significance at k/Mpc{sup ?1} ? 0.0013–0.0025, 0.0362–0.0402 and 0.051–0.056, reflecting the 'WMAP glitches'. To test whether these are indeed real will require more accurate data, such as from the Planck satellite and new ground-based experiments.
EECE 595: SPREAD SPECTRUM COMMUNICATIONS 1 Distributed Power Control in CDMA Cellular
station will corrupt the other signals. Another reason for power control is the battery life time. High of each mobile station. The transmission power of the mobile stations is determined solely on localEECE 595: SPREAD SPECTRUM COMMUNICATIONS 1 Distributed Power Control in CDMA Cellular System Aly El
Relationship between magnetic power spectrum and flare productivity in solar active regions
Relationship between magnetic power spectrum and flare productivity in solar active regions V day, being equal to 1 when the specific flare productivity is one C1.0 flare per day. The power index.I. Abramenko Big Bear Solar Observatory, 40386 N. Shore Lane, Big Bear City, CA 92314, USA ABSTRACT Power
Cornett, John Sheldon
1966-01-01
A STUDY OF WIND VARIABILITY IN THE LOWER TROPOSPHERE THROUGH POWER SPECTRUM ANALYSIS AT MESOSCALE FREQUENCIES A Thesis By JOHN SHELDON CORNETT Submitted to the Graduate College of the Texas A&M University in Partial fulfillment... of the requirements for the degree of MASTER OF SCIENCE January 1966 Major Subject: Meteorology A STUDY OP WIND VARIABILITY IN THE LOWER TROPOSPHERE THROUGH POWER SPECTRUM ANALYSIS AT MESOSCALE FREQUENCIES A Thesis By JOHN SHELDON CORNETT Approved as to style...
The Power Spectrum of Rich Clusters of Galaxies on Large Spatial Scales
Tadros, H; Dalton, G B; Tadros, Helen; Efstathiou, George; Dalton, Gavin
1997-01-01
We present an analysis of the redshift-space power spectrum, $P(k)$, of rich clusters of galaxies based on an automated cluster catalogue selected from the APM Galaxy Survey. We find that $P(k)$ can be approximated by a power law, $P(k)\\proptok^{n}$, with $n\\approx-1.6$ over the wavenumber range $0.04\\hr
Increased Photovoltaic Power Output via Diffractive Spectrum Separation
Kim, Ganghun
In this Letter, we report the preliminary demonstration of a new paradigm for photovoltaic power generation that utilizes a broadband diffractive-optical element (BDOE) to efficiently separate sunlight into laterally spaced ...
Power-laws and Non-Power-laws in Dark Matter Halos
R. N. Henriksen
2006-09-05
Simulated dark matter profiles are often modelled as a `NFW' density profile rather than a single power law. Recently, attention has turned to the rather rigorous power-law behaviour exhibited by the `pseudo phase-space density' of the dark matter halo, which is defined dimensionally in terms of the local density and velocity dispersion of the dark matter particles. The non-power-law behaviour of the density profile is generally taken to exclude simple scale-free, in-fall models; however the power-law behaviour of the `pseudo-density' is a counter indication. We argue in this paper that both behaviours may be at least qualitatively understood in terms of a dynamically evolving self-similarity, rather than the form for self-similar infall that is fixed by cosmological initial conditions. The evolution is likely due to collective relaxation such as that provided by the radial-orbit instability on large scales. We deduce, from a distribution function given by first order coarse-graining, both the NFW-type density profile and the power-law pseudo-density profile. The results are not greatly sensitive to variation about 3 in the power of the velocity dispersion used in the definition of the phase space pseudo-density. We suggest that the power 2 may create the more physical quantity, whose deviations from a power-law are a diagnostic of incomplete relaxation.
Climate Change, Nuclear Power and Nuclear Proliferation: Magnitude Matters
Robert J. Goldston
2010-03-03
Integrated energy, environment and economics modeling suggests electrical energy use will increase from 2.4 TWe today to 12 TWe in 2100. It will be challenging to provide 40% of this electrical power from combustion with carbon sequestration, as it will be challenging to provide 30% from renewable energy sources. Thus nuclear power may be needed to provide ~30% by 2100. Calculations of the associated stocks and flows of uranium, plutonium and minor actinides indicate that the proliferation risks at mid-century, using current light-water reactor technology, are daunting. There are institutional arrangements that may be able to provide an acceptable level of risk mitigation, but they will be difficult to implement. If a transition is begun to fast-spectrum reactors at mid-century, without a dramatic change in the proliferation risks of such systems, at the end of the century proliferation risks are much greater, and more resistant to mitigation. The risks of nuclear power should be compared with the risks of the estimated 0.64oC long-term global surface-average temperature rise predicted if nuclear power were replaced with coal-fired power plants without carbon sequestration. Fusion energy, if developed, would provide a source of nuclear power with much lower proliferation risks than fission.
Solar Gamma Rays Powered by Secluded Dark Matter
Brian Batell; Maxim Pospelov; Adam Ritz; Yanwen Shang
2009-10-08
Secluded dark matter models, in which WIMPs annihilate first into metastable mediators, can present novel indirect detection signatures in the form of gamma rays and fluxes of charged particles arriving from directions correlated with the centers of large astrophysical bodies within the solar system, such as the Sun and larger planets. This naturally occurs if the mean free path of the mediator is in excess of the solar (or planetary) radius. We show that existing constraints from water Cerenkov detectors already provide a novel probe of the parameter space of these models, complementary to other sources, with significant scope for future improvement from high angular resolution gamma-ray telescopes such as Fermi-LAT. Fluxes of charged particles produced in mediator decays are also capable of contributing a significant solar system component to the spectrum of energetic electrons and positrons, a possibility which can be tested with the directional and timing information of PAMELA and Fermi.
Universal power law for the energy spectrum of breaking Riemann waves
Dmitry Pelinovsky; Efim Pelinovsky; Elena Kartashova; Tatjana Talipova; Ayrat Giniyatullin
2013-06-30
The universal power law for the spectrum of one-dimensional breaking Riemann waves is justified for the simple wave equation. The spectrum of spatial amplitudes at the breaking time $t = t_b$ has an asymptotic decay of $k^{-4/3}$, with corresponding energy spectrum decaying as $k^{-8/3}$. This spectrum is formed by the singularity of the form $(x-x_b)^{1/3}$ in the wave shape at the breaking time. This result remains valid for arbitrary nonlinear wave speed. In addition, we demonstrate numerically that the universal power law is observed for long time in the range of small wave numbers if small dissipation or dispersion is accounted in the viscous Burgers or Korteweg-de Vries equations.
No evidence for the blue-tilted power spectrum of relic gravitational waves
Qing-Guo Huang; Sai Wang
2015-02-09
In this paper, we constrain the tilt of the power spectrum of relic gravitational waves by combining the data from BICEP2/Keck array and Planck (BKP) and the Laser Interferometer Gravitational-Waves Observatory (LIGO). From the data of BKP B-modes, the constraint on the tensor tilt is $n_t=0.66^{+1.83}_{-1.44}$ at the $68%$ confidence level. By further adding the LIGO upper limit on the energy density of gravitational waves, the constraint becomes $n_t=-0.76^{+1.37}_{-0.52}$ at the $68%$ confidence level. We conclude that there is no evidence for a blue-tilted power spectrum of relic gravitational waves and either sign of the index of tensor power spectrum is compatible with the data.
Constraining High Redshift X-ray Sources with Next Generation 21 cm Power Spectrum Measurements
Ewall-Wice, Aaron; Mesinger, Andrei; Dillon, Joshua S; Liu, Adrian; Pober, Jonathan
2015-01-01
We use the Fisher matrix formalism and semi-numerical simulations to derive quantitative predictions of the constraints that power spectrum measurements on next-generation interferometers, such as the Hydrogen Epoch of Reionization Array (HERA) and the Square Kilometre Array (SKA), will place on the characteristics of the X-ray sources that heated the high redshift intergalactic medium. Incorporating observations between $z=5$ and $z=25$, we find that the proposed 331 element HERA and SKA phase 1 will be capable of placing $\\lesssim 10\\%$ constraints on the spectral properties of these first X-ray sources, even if one is unable to perform measurements within the foreground contaminated "wedge" or the FM band. When accounting for the enhancement in power spectrum amplitude from spin temperature fluctuations, we find that the observable signatures of reionization extend well beyond the peak in the power spectrum usually associated with it. We also find that lower redshift degeneracies between the signatures of ...
CMB radiation power spectrum in CDM open universes up to 2nd order perturbations
Jose L. Sanz; Enrique Martinez-Gonzalez; Laura Cayon; Joseph Silk; Naoshi Sugiyama
1996-02-28
A second--order perturbation theory approach is developed to calculate temperature anisotropies in the cosmic microwave background. Results are given for open universes and fluctuations corresponding to CDM models with either Harrison-Zeldovich (HZ) or Lyth-Stewart-Ratra-Peebles (LSRP) primordial energy--density fluctuation power spectrum. Our perturbation theory approach provides a distinctive multipole contribution as compared to the primary one, the amplitude of the effect being very dependent on normalization. For low--$\\Omega$ models, the contribution of the secondary multipoles to the radiation power spectrum is negligible both for standard recombination and reionized scenarios, with the 2--year COBE--DMR normalization. For a flat universe this contribution is $\\approx 0.1-10\\%$ depending on the reionization history of the universe and on the normalization of the power spectrum.
Power spectrum and anisotropy of super inflation in loop quantum cosmology
Xiao-Jun Yue; Jian-Yang Zhu
2013-03-25
We investigate the scalar mode of perturbation of super inflation in the version of loop quantum cosmology in which the gauge invariant holonomy corrections are considered. Given a background solution, we calculate the power spectrum of the perturbation in the classical and LQC conditions. Then we compute the anisotropy originated from the perturbation. It is found that in the presence of the gauge invariant holonomy corrections the power spectrum is exponentially blue and the anisotropy also grows exponentially in the epoch of super inflation.
Climate Change, Nuclear Power and Nuclear Proliferation: Magnitude Matters
Robert J. Goldston
2011-04-28
Integrated energy, environment and economics modeling suggests that worldwide electrical energy use will increase from 2.4 TWe today to ~12 TWe in 2100. It will be challenging to provide 40% of this electrical power from combustion with carbon sequestration, as it will be challenging to provide 30% from renewable energy sources derived from natural energy flows. Thus nuclear power may be needed to provide ~30%, 3600 GWe, by 2100. Calculations of the associated stocks and flows of uranium, plutonium and minor actinides indicate that the proliferation risks at mid-century, using current light-water reactor technology, are daunting. There are institutional arrangements that may be able to provide an acceptable level of risk mitigation, but they will be difficult to implement. If a transition is begun to fast-spectrum reactors at mid-century, without a dramatic change in the proliferation risks of such systems, at the end of the century global nuclear proliferation risks are much greater, and more resistant to mitigation. Fusion energy, if successfully demonstrated to be economically competitive, would provide a source of nuclear power with much lower proliferation risks than fission.
The coyote universe extended: Precision emulation of the matter...
Office of Scientific and Technical Information (OSTI)
The coyote universe extended: Precision emulation of the matter power spectrum Citation Details In-Document Search Title: The coyote universe extended: Precision emulation of the...
P. A. Sturrock
2008-09-01
The usual procedure for estimating the significance of a peak in a power spectrum is to calculate the probability of obtaining that value or a larger value by chance, on the assumption that the time series contains only noise (e.g. that the measurements were derived from random samplings of a Gaussian distribution). However, it is known that one should regard this P-Value approach with caution. As an alternative, we here examine a Bayesian approach to estimating the significance of a peak in a power spectrum. This approach requires that we consider explicitly the hypothesis that the time series contains a periodic signal as well as noise. The challenge is to identify a probability distribution function for the power that is appropriate for this hypothesis. We propose what seem to be reasonable conditions to require of this function, and then propose a simple function that meets these requirements. We also propose a consistency condition, and check to see that our function satisfies this condition. We find that the Bayesian significance estimates are considerably more conservative than the conventional estimates. We apply this procedure to three recent analyses of solar neutrino data: (a) bimodality of GALLEX data; (b) power spectrum analysis of Super-Kamiokande data; and (c) the combined analysis of radiochemical neutrino data and irradiance data.
An alternative power spectrum of the resonance fluorescence of atomic systems
Adam Stokes; Almut Beige
2014-08-31
We adopt an open quantum systems perspective to calculate the power spectrum associated with the electric field generated by an atomic dipole moment undergoing resonant laser-driving. This spectrum has a similar shape to the usual Mollow spectrum, but also has some distinct features. For sufficiently strong laser driving, both spectra have a symmetric triplet structure with a large central peak and two sidebands. However, the relative height of the sidebands to the central peak differs in each case. The two spectra also behave quite differently when the laser Rabi frequency is varied. Both spectra may be of interest in high-precision experiments into the quantum physics of atomic systems, especially artificial atoms.
Peaks and Troughs in Helioseismology: The Power Spectrum of Solar Oscillations
Colin S. Rosenthal
1998-04-15
I present a matched-wave asymptotic analysis of the driving of solar oscillations by a general localised source. The analysis provides a simple mathematical description of the asymmetric peaks in the power spectrum in terms of the relative locations of eigenmodes and troughs in the spectral response. It is suggested that the difference in measured phase function between the modes and the troughs in the spectrum will provide a key diagnostic of the source of the oscillations. I also suggest a form for the asymmetric line profiles to be used in the fitting of solar power spectra. Finally I present a comparison between the numerical and asymptotic descriptions of the oscillations. The numerical results bear out the qualitative features suggested by the asymptotic analysis but suggest that numerical calculations of the locations of the troughs will be necessary for a quantitative comparison with the observations.
Liu, W J; Ding, M D; Fang, C
2008-01-01
The direct current (DC) electric field near the reconnection region has been proposed as an effective mechanism to accelerate protons and electrons in solar flares. A power-law energy spectrum was generally claimed in the simulations of electron acceleration by the reconnection electric field. However, in most of the literature, the electric and magnetic fields were chosen independently. In this paper, we perform test particle simulations of electron acceleration in reconnecting magnetic field, where both the electric and magnetic fields are adopted from numerical simulations of the MHD equations. It is found that the accelerated electrons present a truncated power-law energy spectrum with an exponential tail at high energies, which is analogous to the case of diffusive shock acceleration. The influences of the reconnection parameters on the spectral feature are also investigated, such as the longitudinal and transverse components of the magnetic field and the size of the current sheet. It is suggested that t...
Neutrino mass limits: robust information from the power spectrum of galaxy surveys
Antonio J. Cuesta; Viviana Niro; Licia Verde
2015-11-18
We present cosmological upper limits on the sum of active neutrino masses using large-scale power spectrum data from the WiggleZ Dark Energy Survey and from the Sloan Digital Sky Survey - Data Release 7 (SDSS-DR7) sample of Luminous Red Galaxies (LRG). Combining measurements on the Cosmic Microwave Background temperature and polarisation anisotropies by the Planck satellite together with WiggleZ power spectrum results in a neutrino mass bound of 0.43 eV at 95% C.L., while replacing WiggleZ by the SDSS-DR7 LRG power spectrum, the 95% C.L. bound on the sum of neutrino masses improves to 0.17 eV. Adding Baryon Acoustic Oscillation (BAO) distance scale measurements, the neutrino mass upper limits greatly improve, since BAO data break degeneracies in parameter space. Within a $\\Lambda$CDM model, we find an upper limit of 0.11 eV (0.15 eV) at 95% C.L., when using SDSS-DR7 LRG (WiggleZ) together with BAO and Planck. The addition of BAO data makes the neutrino mass upper limit robust, showing only a weak dependence on the power spectrum used. We also quantify the dependence of neutrino mass limit reported here on the CMB lensing information. The tighter upper limit (0.11 eV) obtained with SDSS-DR7 LRG is very close to that recently obtained using Lyman-alpha clustering data, yet uses a completely different probe and redshift range, further supporting the robustness of the constraint. This constraint puts under some pressure the inverted mass hierarchy and favours the normal hierarchy.
Neutrino mass limits: robust information from the power spectrum of galaxy surveys
Cuesta, Antonio J; Verde, Licia
2015-01-01
We present cosmological upper limits on the sum of active neutrino masses using large-scale power spectrum data from the WiggleZ Dark Energy Survey and from the Sloan Digital Sky Survey - Data Release 7 (SDSS-DR7) sample of Luminous Red Galaxies (LRG). Combining measurements on the Cosmic Microwave Background temperature and polarisation anisotropies by the Planck satellite together with WiggleZ power spectrum results in a neutrino mass bound of 0.43 eV at 95% C.L., while replacing WiggleZ by the SDSS-DR7 LRG power spectrum, the 95% C.L. bound on the sum of neutrino masses improves to 0.17 eV. Adding Baryon Acoustic Oscillation (BAO) distance scale measurements, the neutrino mass upper limits greatly improve, since BAO data break degeneracies in parameter space. Within a $\\Lambda$CDM model, we find an upper limit of 0.11 eV (0.15 eV) at 95% C.L., when using SDSS-DR7 LRG (WiggleZ) together with BAO and Planck. The addition of BAO data makes the neutrino mass upper limit robust, showing only a weak dependence o...
Power spectrum sensitivity of raster-scanned CMB experiments in the presence of 1/f noise
Tom Crawford
2007-09-24
We investigate the effects of 1/f noise on the ability of a particular class of Cosmic Microwave Background experiments to measure the angular power spectrum of temperature anisotropy. We concentrate on experiments that operate primarily in raster-scan mode and develop formalism that allows us to calculate analytically the effect of 1/f noise on power spectrum sensitivity for this class of experiments and determine the benefits of raster-scanning at different angles relative to the sky field versus scanning at only a single angle (cross-linking versus not cross-linking). We find that the sensitivity of such experiments in the presence of 1/f noise is not significantly degraded at moderate spatial scales (l ~ 100) for reasonable values of scan speed and 1/f knee. We further find that the difference between cross-linked and non-cross-linked experiments is small in all cases and that the non-cross-linked experiments are preferred from a raw sensitivity standpoint in the noise-dominated regime -- i.e., in experiments in which the instrument noise is greater than the sample variance of the target power spectrum at the scales of interest. This analysis does not take into account systematic effects.
Kirchner, James W.
(FFT), the maximum entropy method (MEM), and the Lomb^Scargle Fourier transform (LSFT). Their use of R their conclusions on two power spectra (their ˘gure 3b,c) that were calculated by the MEM and LSFT after polynomial
A search for signatures of dark matter in the AMS-01 electron and antiproton spectrum
Carosi, Gianpaolo Patrick
2006-01-01
If dark matter consists of Weakly Interacting Massive Particles (WIMPs), such as the supersymmetric neutralino, various theories predict that their annihilation in the galaxy can give rise to anomalous features in the ...
Power spectrum analysis of polarized emission from the Canadian galactic plane survey
Stutz, R. A.; Rosolowsky, E. W. [University of British Columbia Okanagan, 3333 University Way, Kelowna BC, V1V 1V7 (Canada); Kothes, R.; Landecker, T. L. [National Research Council Canada, Dominion Radio Astrophysical Observatory, Box 248, Penticton, BC, V2A 6J9 (Canada)
2014-05-20
Angular power spectra are calculated and presented for the entirety of the Canadian Galactic Plane Survey polarization data set at 1.4 GHz covering an area of 1060 deg{sup 2}. The data analyzed are a combination of data from the 100 m Effelsberg Telescope, the 26 m Telescope at the Dominion Radio Astrophysical Observatory, and the Synthesis Telescope at the Dominion Radio Astrophysical Observatory, allowing all scales to be sampled down to arcminute resolution. The resulting power spectra cover multipoles from ? ? 60 to ? ? 10{sup 4} and display both a power-law component at low multipoles and a flattening at high multipoles from point sources. We fit the power spectrum with a model that accounts for these components and instrumental effects. The resulting power-law indices are found to have a mode of 2.3, similar to previous results. However, there are significant regional variations in the index, defying attempts to characterize the emission with a single value. The power-law index is found to increase away from the Galactic plane. A transition from small-scale to large-scale structure is evident at b = 9°, associated with the disk-halo transition in a 15° region around l = 108°. Localized variations in the index are found toward H II regions and supernova remnants, but the interpretation of these variations is inconclusive. The power in the polarized emission is anticorrelated with bright thermal emission (traced by H? emission) indicating that the thermal emission depolarizes background synchrotron emission.
The Power of Efficiency: Why Momentum Savings Really Do Matter
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Efficiency: Why Momentum Savings Really Do Matter It's easy to dismiss Momentum Savings. After all, they can be difficult to understand and quantify in comparison to the direct...
The Turbulence Velocity Power Spectrum of Neutral Hydrogen in the Small Magellanic Cloud
Chepurnov, Alexey; Lazarian, Alex; Stanimirovic, Snezana
2015-01-01
We present the results of the Velocity Coordinate Spectrum (VCS) technique to calculate the velocity power spectrum of turbulence in the Small Magellanic Cloud (SMC) in 21cm emission. We have obtained a velocity spectral index of -3.85 and an injection scale of 2.3 kpc. The spectral index is steeper than the Kolmogorov index which is expected for shock-dominated turbulence which is in agreement with past works on the SMC gas dynamics. The injection scale of 2.3 kpc suggests that tidal interactions with the Large Magellanic Cloud are the dominate driver of turbulence in this dwarf galaxy. This implies turbulence maybe driven by multiple mechanisms in galaxies in addition to supernova injection and that galaxy-galaxy interactions may play an important role.
arXiv:0910.2237v1[astro-ph.CO]12Oct2009 Generalized Slow Roll for Large Power Spectrum Features
Hu, Wayne
approximation provides a model-independent technique for computing the initial curvature power spectrum, features in the inflaton potential produce features in the power spectrum. Glitches in the observedarXiv:0910.2237v1[astro-ph.CO]12Oct2009 Generalized Slow Roll for Large Power Spectrum Features
B. Novosyadlyj; S. Apunevych
2004-12-02
We carry out the determination of the amplitude of relic gravitational waves power spectrum. Indirect best-fit technique was applied to compare observational data and theory predictions. As observations we have used data on large-scale structure (LSS) of the Universe and anisotropy of cosmic microwave background (CMB) temperature. The conventional inflationary model with 11 parameters has been investigated, all of them evaluated jointly. This approach gave us a possibility to find parameters of power spectrum of gravitational waves along with statistical errors. The main result consists in following: WMAP data on power spectrum of CMB temperature fluctuations along with LSS data prefer model with small amplitude of tensor mode power spectrum, close to zero. The upper limit for its amplitude at quadupole harmonics T/S=0.6 at 95% C.L.
W. J. Liu; P. F. Chen; M. D. Ding; C. Fang
2009-01-10
The direct current (DC) electric field near the reconnection region has been proposed as an effective mechanism to accelerate protons and electrons in solar flares. A power-law energy spectrum was generally claimed in the simulations of electron acceleration by the reconnection electric field. However in most of the literature, the electric and magnetic fields were chosen independently. In this paper, we perform test-particle simulations of electron acceleration in a reconnecting magnetic field, where both the electric and magnetic fields are adopted from numerical simulations of the MHD equations. It is found that the accelerated electrons present a truncated power-law energy spectrum with an exponential tail at high energies, which is analogous to the case of diffusive shock acceleration. The influences of reconnection parameters on the spectral feature are also investigated, such as the longitudinal and transverse components of the magnetic field and the size of the current sheet. It is suggested that the DC electric field alone might not be able to reproduce the observed single or double power-law distributions.
Federico Agustin Membiela; Mauricio Bellini
2007-12-18
Introducing a variable cosmological parameter $\\Lambda (t)$ in a geometrical manner from a 5D Riemann-flat metric, we investigate the origin and evolution of primordial magnetic fields in the early universe, when the expansion is governed by a cosmological parameter $\\Lambda (t)$ that decreases with time. Using the gravitoelectromagnetic inflationary formalism, but without the Feynman gauge, we obtain the power of spectrums for large-scale magnetic fields and the inflaton field fluctuations during inflation. A very important fact is that our formalism is {\\em naturally non-conformally invariant}.
Angular Signatures of Dark Matter in the Diffuse Gamma Ray Spectrum
Hooper, Dan; Serpico, Pasquale D.; /Fermilab
2007-02-01
Dark matter annihilating in our Galaxy's halo and elsewhere in the universe is expected to generate a diffuse flux of gamma rays, potentially observable with next generation satellite-based experiments, such as GLAST. In this article, we study the signatures of dark matter in the angular distribution of this radiation. Pertaining to the extragalactic contribution, we discuss the effect of the motion of the solar system with respect to the cosmological rest frame, and anisotropies due to the structure of our local universe. For the gamma ray flux from dark matter in our own Galactic halo, we discuss the effects of the offset position of the solar system, the Compton-Getting effect, the asphericity of the Milky Way halo, and the signatures of nearby substructure. We explore the prospects for the detection of these features by the GLAST satellite and find that, if {approx} 10% or more of the diffuse gamma ray background observed by EGRET is the result of dark matter annihilations, then GLAST should be sensitive to anisotropies down to the 0.1% level. Such precision would be sufficient to detect many, if not all, of the signatures discussed in this paper.
Nonlinear modulation of the HI power spectrum on ultra-large scales. I
Umeh, Obinna; Santos, Mario
2015-01-01
Intensity mapping of the neutral hydrogen brightness temperature promises to provide a three-dimensional view of the universe on very large scales. Nonlinear effects are typically thought to alter only the small-scale power, but we show how they can bias the extraction of cosmological information contained in the power spectrum on ultra-large scales. For linear perturbations to remain valid on large scales, we need to renormalize perturbations at higher order. In the case of intensity mapping, the second-order contribution to clustering from weak lensing dominates nonlinear contribution at high redshift. Renormalization modifies the mean brightness temperature and therefore the evolution bias. It also introduces a term that mimics white noise. These effects can influence forecasting analysis on ultra-large scales.
Araujo, D.; Dumoulin, R. N.; Newburgh, L. B.; Zwart, J. T. L. [Department of Physics and Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Bischoff, C.; Brizius, A.; Buder, I.; Kusaka, A. [Kavli Institute for Cosmological Physics, Department of Physics, Enrico Fermi Institute, The University of Chicago, Chicago, IL 60637 (United States); Chinone, Y. [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801 (Japan); Cleary, K.; Reeves, R. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, 1200 E. California Blvd M/C 249-17, Pasadena, CA 91125 (United States); Monsalve, R.; Bustos, R. [Department of Physics, University of Miami, 1320 Campo Sano Drive, Coral Gables, FL 33146 (United States); Naess, S. K.; Eriksen, H. K. [Institute of Theoretical Astrophysics, University of Oslo, P.O. Box 1029 Blindern, NO-0315 Oslo (Norway); Wehus, I. K. [Department of Astrophysics, University of Oxford, Keble Road, Oxford OX1 3RH (United Kingdom); Bronfman, L. [Departamento de Astronomia, Universidad de Chile, Casilla 36-D, Santiago (Chile); Church, S. E. [Kavli Institute for Particle Astrophysics and Cosmology and Department of Physics, Stanford University, Varian Physics Building, 382 Via Pueblo Mall, Stanford, CA 94305 (United States); Dickinson, C. [Jodrell Bank Centre for Astrophysics, Alan Turing Building, School of Physics and Astronomy, The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Gaier, T., E-mail: ibuder@uchicago.edu [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109 (United States); Collaboration: QUIET Collaboration; and others
2012-12-01
The Q/U Imaging ExperimenT (QUIET) has observed the cosmic microwave background (CMB) at 43 and 95 GHz. The 43 GHz results have been published in a previous paper, and here we report the measurement of CMB polarization power spectra using the 95 GHz data. This data set comprises 5337 hr of observations recorded by an array of 84 polarized coherent receivers with a total array sensitivity of 87 {mu}K{radical}s. Four low-foreground fields were observed, covering a total of {approx}1000 deg{sup 2} with an effective angular resolution of 12.'8, allowing for constraints on primordial gravitational waves and high signal-to-noise measurements of the E-modes across three acoustic peaks. The data reduction was performed using two independent analysis pipelines, one based on a pseudo-C {sub l} (PCL) cross-correlation approach, and the other on a maximum-likelihood (ML) approach. All data selection criteria and filters were modified until a predefined set of null tests had been satisfied before inspecting any non-null power spectrum. The results derived by the two pipelines are in good agreement. We characterize the EE, EB, and BB power spectra between l = 25 and 975 and find that the EE spectrum is consistent with {Lambda}CDM, while the BB power spectrum is consistent with zero. Based on these measurements, we constrain the tensor-to-scalar ratio to r = 1.1{sup +0.9} {sub -0.8} (r < 2.8 at 95% C.L.) as derived by the ML pipeline, and r = 1.2{sup +0.9} {sub -0.8} (r < 2.7 at 95% C.L.) as derived by the PCL pipeline. In one of the fields, we find a correlation with the dust component of the Planck Sky Model, though the corresponding excess power is small compared to statistical errors. Finally, we derive limits on all known systematic errors, and demonstrate that these correspond to a tensor-to-scalar ratio smaller than r = 0.01, the lowest level yet reported in the literature.
Second Season QUIET Observations: Measurements of the CMB Polarization Power Spectrum at 95 GHz
Araujo, D.; Bischoff, C.; Brizius, A.; Buder, I.; Chinone, Y.; Cleary, K.; Dumoulin, R.N.; Kusaka, A.; Monsalve, R.; ss, S.K.N\\ae; Newburgh, L.B.; /Columbia U., CBA /Princeton U. /Caltech
2012-07-01
The Q/U Imaging ExperimenT (QUIET) has observed the cosmic microwave background (CMB) at 43 and 95GHz. The 43-GHz results have been published in QUIET Collaboration et al. (2011), and here we report the measurement of CMB polarization power spectra using the 95-GHz data. This data set comprises 5337 hours of observations recorded by an array of 84 polarized coherent receivers with a total array sensitivity of 87 {mu}K{radical}s. Four low-foreground fields were observed, covering a total of {approx} 1000 square degrees with an effective angular resolution of 12'.8, allowing for constraints on primordial gravitational waves and high-signal-to-noise measurements of the E-modes across three acoustic peaks. The data reduction was performed using two independent analysis pipelines, one based on a pseudo-C{ell} (PCL) cross-correlation approach, and the other on a maximum-likelihood (ML) approach. All data selection criteria and filters were modified until a predefined set of null tests had been satisfied before inspecting any non-null power spectrum. The results derived by the two pipelines are in good agreement. We characterize the EE, EB and BB power spectra between {ell} = 25 and 975 and find that the EE spectrum is consistent with {Lambda}CDM, while the BB power spectrum is consistent with zero. Based on these measurements, we constrain the tensor-to-scalar ratio to r = 1.1{sup +0.9}{sub -0.8} (r < 2.8 at 95% C.L.) as derived by the ML pipeline, and r = {sup +0.9}{sub -0.8} (r < 2.7 at 95% C.L.) as derived by the PCL pipeline. In one of the fields, we find a correlation with the dust component of the Planck Sky Model, though the corresponding excess power is small compared to statistical errors. Finally, we derive limits on all known systematic errors, and demonstrate that these correspond to a tensor-to-scalar ratio smaller than r = 0.01, the lowest level yet reported in the literature.
Early structure formation from primordial density fluctuations with a blue-tilted power spectrum
Hirano, Shingo; Yoshida, Naoki; Spergel, David; Yorke, Harold W
2015-01-01
While observations of large-scale structure and the cosmic microwave background (CMB) provide strong constraints on the amplitude of the primordial power spectrum (PPS) on scales larger than 10 Mpc, the amplitude of the power spectrum on sub-galactic length scales is much more poorly constrained. We study early structure formation in a cosmological model with a blue-tilted PPS. We assume that the standard scale-invariant PPS is modified at small length scales as $P(k) \\sim k^{m_{\\rm s}}$ with $m_{\\rm s} > 1$. We run a series of cosmological hydrodynamic simulations to examine the dependence of the formation epoch and the characteristic mass of primordial stars on the tilt of the PPS. In models with $m_{\\rm s} > 1$, star-forming gas clouds are formed at $z > 100$, when formation of hydrogen molecules is inefficient because the intense CMB radiation destroys chemical intermediates. Without efficient coolant, the gas clouds gravitationally contract while keeping a high temperature. The protostars formed in such ...
Power Spectrum of Out-of-equilibrium Forces in Living Cells : Amplitude and Frequency Dependence
Francois Gallet; Delphine Arcizet; Pierre Bohec; Alain Richert
2009-01-20
Living cells exhibit an important out-of-equilibrium mechanical activity, mainly due to the forces generated by molecular motors. These motor proteins, acting individually or collectively on the cytoskeleton, contribute to the violation of the fluctuation-dissipation theorem in living systems. In this work we probe the cytoskeletal out-of-equilibrium dynamics by performing simultaneous active and passive microrheology experiments, using the same micron-sized probe specifically bound to the actin cortex. The free motion of the probe exhibits a constrained, subdiffusive behavior at short time scales (t power law dependence with time. Combining the results of both experiments, we precisely measure for the first time the power spectrum of the force fluctuations exerted on this probe, which lies more than one order of magnitude above the spectrum expected at equilibrium, and greatly depends on frequency. We retrieve an effective temperature Teff of the system, as an estimate of the departure from thermal equilibrium. This departure is especially pronounced on long time scales, where Teff bears the footprint of the cooperative activity of motors pulling on the actin network. ATP depletion reduces the fluctuating force amplitude and results in a sharp decrease of Teff towards equilibrium.
More on loops in reheating: non-gaussianities and tensor power spectrum
Katirci, Nihan; Kaya, Ali; Tarman, Merve E-mail: ali.kaya@boun.edu.tr
2014-06-01
We consider the single field chaotic m{sup 2}?{sup 2} inflationary model with a period of preheating, where the inflaton decays to another scalar field ? in the parametric resonance regime. In a recent work, one of us has shown that the ? modes circulating in the loops during preheating notably modify the (??) correlation function. We first rederive this result using a different gauge condition hence reconfirm that superhorizon ? modes are affected by the loops in preheating. Further, we examine how ? loops give rise to non-gaussianity and affect the tensor perturbations. For that, all cubic and some higher order interactions involving two ? fields are determined and their contribution to the non-gaussianity parameter f{sub NL} and the tensor power spectrum are calculated at one loop. Our estimates for these corrections show that while a large amount of non-gaussianity can be produced during reheating, the tensor power spectrum receive moderate corrections. We observe that the loop quantum effects increase with more ? fields circulating in the loops indicating that the perturbation theory might be broken down. These findings demonstrate that the loop corrections during reheating are significant and they must be taken into account for precision inflationary cosmology.
Anisotropic power spectrum and bispectrum in the f(?)F˛ mechanism
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Bartolo, Nicola; Matarrese, Sabino; Peloso, Marco; Ricciardone, Angelo
2013-01-01
A suitable coupling of the inflaton ? to a vector kinetic term F˛ gives frozen and scale invariant vector perturbations. We compute the cosmological perturbations ? that result from such coupling by taking into account the classical vector field that unavoidably gets generated at large scales during inflation. This generically results in a too-anisotropic power spectrum of ?. Specifically, the anisotropy exceeds the 1% level (10% level) if inflation lasts ~5 e-folds (~50 e-folds) more than the minimal amount required to produce the cosmic microwave background modes. This conclusion applies, among others, to the application of this mechanism for magnetogenesis, for anisotropic inflation, and for the generation of anisotropic perturbations at the end of inflation through a waterfall field coupled to the vector (in this case, the unavoidable contribution that we obtain is effective all throughout inflation, and it is independent of the waterfall field). For a tuned duration of inflation, a 1% (10%) anisotropy in the power spectrum corresponds to an anisotropic bispectrum which is enhanced like the local one in the squeezed limit, and with an effective local fNL~3(~30). More in general, a significant anisotropy of the perturbations may be a natural outcome of all models that sustain higher than 0 spin fields during inflation.
Anisotropic power spectrum and bispectrum in the f(?)F˛ mechanism
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Bartolo, Nicola; Matarrese, Sabino; Peloso, Marco; Ricciardone, Angelo
2013-01-04
A suitable coupling of the inflaton ? to a vector kinetic term F˛ gives frozen and scale invariant vector perturbations. We compute the cosmological perturbations ? that result from such coupling by taking into account the classical vector field that unavoidably gets generated at large scales during inflation. This generically results in a too-anisotropic power spectrum of ?. Specifically, the anisotropy exceeds the 1% level (10% level) if inflation lasts ~5 e-folds (~50 e-folds) more than the minimal amount required to produce the cosmic microwave background modes. This conclusion applies, among others, to the application of this mechanism for magnetogenesis,more »for anisotropic inflation, and for the generation of anisotropic perturbations at the end of inflation through a waterfall field coupled to the vector (in this case, the unavoidable contribution that we obtain is effective all throughout inflation, and it is independent of the waterfall field). For a tuned duration of inflation, a 1% (10%) anisotropy in the power spectrum corresponds to an anisotropic bispectrum which is enhanced like the local one in the squeezed limit, and with an effective local fNL~3(~30). More in general, a significant anisotropy of the perturbations may be a natural outcome of all models that sustain higher than 0 spin fields during inflation.« less
On the Soft Limit of the Large Scale Structure Power Spectrum: UV Dependence
Mathias Garny; Thomas Konstandin; Rafael A. Porto; Laura Sagunski
2015-08-25
We derive a non-perturbative equation for the large scale structure power spectrum of long-wavelength modes. Thereby, we use an operator product expansion together with relations between the three-point function and power spectrum in the soft limit. The resulting equation encodes the coupling to ultraviolet (UV) modes in two time-dependent coefficients, which may be obtained from response functions to (anisotropic) parameters, such as spatial curvature, in a modified cosmology. We argue that both depend weakly on fluctuations deep in the UV. As a byproduct, this implies that the renormalized leading order coefficient(s) in the effective field theory (EFT) of large scale structures receive most of their contribution from modes close to the non-linear scale. Consequently, the UV dependence found in explicit computations within standard perturbation theory stems mostly from counter-term(s). We confront a simplified version of our non-perturbative equation against existent numerical simulations, and find good agreement within the expected uncertainties. Our approach can in principle be used to precisely infer the relevance of the leading order EFT coefficient(s) using small volume simulations in an `anisotropic separate universe' framework. Our results suggest that the importance of these coefficient(s) is a $\\sim 10 \\%$ effect, and plausibly smaller.
Power spectrum in the Chaplygin gas model: tachyonic, fluid and scalar field representations
C. E. M. Batista; J. C. Fabris; M. Morita
2009-04-24
The Chaplygin gas model, characterized by an equation of state of the type $p = - \\frac{A}{\\rho}$ emerges naturally from the Nambu-Goto action of string theory. This fluid representation can be recast under the form of a tachyonic field given by a Born-Infeld type Lagrangian. At the same time, the Chaplygin gas equation of state can be obtained from a self-interacting scalar field. We show that, from the point of view of the supernova type Ia data, the three representations (fluid, tachyonic, scalar field) lead to the same results. However, concerning the matter power spectra, while the fluid and tachyonic descriptions lead to exactly the same results, the self-interacting scalar field representation implies different statistical estimations for the parameters. In particular, the estimation for the dark matter density parameter in the fluid representation favors a universe dominated almost completely by dark matter, while in the self-interacting scalar field representation the prediction is very closed to that obtained in the $\\Lambda$CDM model.
The power spectrum of the Milky Way: Velocity fluctuations in the Galactic disk
Bovy, Jo; Pérez, Ana E García; Zasowski, Gail
2014-01-01
We investigate the kinematics of stars in the mid-plane of the Milky Way on scales between 25 pc and 10 kpc with data from the Apache Point Observatory Galactic Evolution Experiment (APOGEE), the Radial Velocity Experiment (RAVE), and the Geneva-Copenhagen Survey (GCS). Using red-clump stars in APOGEE, we determine the large-scale line-of-sight velocity field out to 5 kpc from the Sun in (0.75 kpc)^2 bins. The solar motion is the largest contribution to the power on large scales after subtracting an axisymmetric rotation field; we determine the solar motion by minimizing the large-scale power to be V_sun = 24+/-1 (ran.)+/-2 (syst [V_c])+/-5 (syst. [large-scale]) km/s, where the systematic uncertainty is due to (a) a conservative 20 km/s uncertainty in V_c and (b) the estimated power on unobserved larger scales. Combining the APOGEE peculiar-velocity field with red-clump stars in RAVE out to 2 kpc from the Sun and with local GCS stars, we determine the power spectrum of residual velocity fluctuations in the Mi...
VES-0071- In the Matter of Mississippi Power Company
Office of Energy Efficiency and Renewable Energy (EERE)
On May 1, 2000, the Mississippi Power Company, of Gulfport, Mississippi (Mississippi Power), filed with the Office of Hearings and Appeals (OHA) of the Department of Energy an Application for...
Time Variations of the Superkamiokande Solar Neutrino Flux Data by Rayleigh Power Spectrum Analysis
Koushik Ghosh; Probhas Raychaudhuri
2006-06-05
We have used the Rayleigh Power Spectrum Analysis of the solar neutrino flux data from 1) 5-day-long samples from Super-Kamiokande-I detector during the period from June, 1996 to July, 2001; 2) 10 -day-long samples from the same detector during the same period and (3) 45-day long from the same detector during the same period. According to our analysis (1) gives periodicities around 0.25, 23.33, 33.75 and 42.75 months; (2) exhibits periodicities around 0.5, 1.0, 28.17, 40.67 and 52.5 months and (3) shows periodicities around 16.5 and 28.5 months. We have found almost similar periods in the solar flares, sunspot data, solar proton data.
Mathews, G J; Ichiki, K; Kajino, T
2015-01-01
The power spectrum of the cosmic microwave background from both the Planck and WMAP data exhibits a slight dip in for multipoles in the range of l=10-30. We show that such a dip could be the result of resonant creation of a massive particle that couples to the inflaton field. For our best-fit models, epochs of resonant particle creation reenters the horizon at wave numbers of k* ~ 0.00011 (h/Mpc). The amplitude and location of these features correspond to the creation of a number of degenerate fermion species of mass ~ 15 times the planck mass during inflation with a coupling constant between the inflaton field and the created fermion species of near unity. Although the evidence is marginal, if this interpretation is correct, this could be one of the first observational hints of new physics at the Planck scale.
Disentangling redshift-space distortions and nonlinear bias using the 2D power spectrum
Jennings, Elise
2015-01-01
We present the nonlinear 2D galaxy power spectrum, $P(k,\\mu)$, in redshift space, measured from the Dark Sky simulations, using galaxy catalogs constructed with both halo occupation distribution and subhalo abundance matching methods, chosen to represent an intermediate redshift sample of luminous red galaxies. We find that the information content in individual $\\mu$ (cosine of the angle to the line of sight) bins is substantially richer then multipole moments, and show that this can be used to isolate the impact of nonlinear growth and redshift space distortion (RSD) effects. Using the $\\muextract the nonlinear bias successfully removes a large parameter degeneracy when constraining the linear growth rate of structure. We carry out a joint parameter estimation, using the low $\\mu$ simulation data to ...
Discovery of 0.08 Hz QPO in the power spectrum of black hole candidate XTE J1118+480
M. Revnivtsev; R. Sunyaev; K. Borozdin
2000-05-10
We found a strong QPO feature at 0.085+/-0.002 Hz in the power spectrum of X-ray transient XTE J1118+480. The QPO was detected in PCA/RXTE data with an amplitude close to 10% rms, and the width 0.034+/-0.006 Hz. The shape of the power spectrum is typical for black hole candidates: almost flat at frequencies lower than 0.03 Hz, roughly power law with slope ~1.2 from 0.03 to 1 Hz, with a following steepening to ~1.6 at higher frequencies. The hard energy spectrum detected up to ~150 keV and the absence of significant X-ray variability at the high frequencies above 100 Hz strongly support the identification of XTE J1118+480 as black hole transient.
Dorn, Sebastian; Enßlin, Torsten A.; Ramirez, Erandy; Kunze, Kerstin E.
2014-06-01
We present a generic inference method for inflation models from observational data by the usage of higher-order statistics of the curvature perturbation on uniform density hypersurfaces. This method is based on the calculation of the posterior for the primordial non-Gaussianity parameters f{sub NL} and g{sub NL}, which in general depend on specific parameters of inflation and reheating models, and enables to discriminate among the still viable inflation models. To keep analyticity as far as possible to dispense with numerically expensive sampling techniques a saddle-point approximation is introduced, whose precision is validated for a numerical toy example. The mathematical formulation is done in a generic way so that the approach remains applicable to cosmic microwave background data as well as to large scale structure data. Additionally, we review a few currently interesting inflation models and present numerical toy examples thereof in two and three dimensions to demonstrate the efficiency of the higher-order statistics method. A second quantity of interest is the primordial power spectrum. Here, we present two Bayesian methods to infer it from observational data, the so called critical filter and an extension thereof with smoothness prior, both allowing for a non-parametric spectrum reconstruction. These methods are able to reconstruct the spectra of the observed perturbations and the primordial ones of curvature perturbation even in case of non-Gaussianity and partial sky coverage. We argue that observables like T- and B-modes permit to measure both spectra. This also allows to infer the level of non-Gaussianity generated since inflation.
Pavin, Nenad
Spectral Densities and Frequencies in the Power Spectrum of Higher Order Repeat Alpha Satellite in Human DNA Molecule* Vladimir Paar,a,** Nenad Pavin,a Ivan Basar,a Marija Rosandi},b Ivica Luketin was applied to the central segment of a fully sequenced genomic seg- ment from the centromeric region in human
Reforming the Power Sector in Transition: Do Institutions Matter?
Nepal, Rabindra; Jamasb, Tooraj
and Uzbekistan. Besides these countries, Turkey and Mongolia are also included in the group of transition economies as per European Bank of Reconstruction and Development (EBRD) areas of operation. 2 For instance, the oil and gas exports for Turkmenistan... ). Stiglitz (1999) argues that the enforcement mechanisms of reforms (including power sector reforms) were weak as the state’s legal and judicial capacities were limited during the transition process brewing inefficient rent...
A multifrequency angular power spectrum analysis of the Leiden polarization surveys
Laura La Porta; Carlo Burigana
2006-06-29
The Galactic synchrotron emission is expected to be the most relevant source of astrophysical contamination in cosmic microwave background polarization measurements, at least at frequencies 30'. We present a multifrequency analysis of the Leiden surveys, linear polarization surveys covering essentially the Northern Celestial Hemisphere at five frequencies between 408 MHz and 1411 MHz. By implementing specific interpolation methods to deal with these irregularly sampled data, we produced maps of the polarized diffuse Galactic radio emission with pixel size of 0.92 deg. We derived the angular power spectrum (APS) (PI, E, and B modes) of the synchrotron dominated radio emission as function of the multipole, l. We considered the whole covered region and some patches at different Galactic latitudes. By fitting the APS in terms of power laws (C_l = k l^a), we found spectral indices that steepen with increasing frequency: from a = -(1-1.5) at 408 MHz to a = -(2-3) at 1411 MHz for 10 < l < 100 and from a = -0.7 to a = -1.5 for lower multipoles (the exact values depending on the considered sky region and polarization mode). The bulk of this steepening can be interpreted in terms of Faraday depolarization effects. We then considered the APS at various fixed multipoles and its frequency dependence. Using the APSs of the Leiden surveys at 820 MHz and 1411 MHz, we determined possible ranges for the rotation measure, RM, in the simple case of an interstellar medium slab model. Taking also into account the polarization degree at 1.4 GHz, we could break the degeneracy between the identified RM intervals. The most reasonable of them turned out to be RM = 9-17 rad/m^2.
Constraining models of f(R) gravity with Planck and WiggleZ power spectrum data
Dossett, Jason; Parkinson, David; Hu, Bin E-mail: hu@lorentz.leidenuniv.nl
2014-03-01
In order to explain cosmic acceleration without invoking ''dark'' physics, we consider f(R) modified gravity models, which replace the standard Einstein-Hilbert action in General Relativity with a higher derivative theory. We use data from the WiggleZ Dark Energy survey to probe the formation of structure on large scales which can place tight constraints on these models. We combine the large-scale structure data with measurements of the cosmic microwave background from the Planck surveyor. After parameterizing the modification of the action using the Compton wavelength parameter B{sub 0}, we constrain this parameter using ISiTGR, assuming an initial non-informative log prior probability distribution of this cross-over scale. We find that the addition of the WiggleZ power spectrum provides the tightest constraints to date on B{sub 0} by an order of magnitude, giving log{sub 10}(B{sub 0}) < ?4.07 at 95% confidence limit. Finally, we test whether the effect of adding the lensing amplitude A{sub Lens} and the sum of the neutrino mass ?m{sub ?} is able to reconcile current tensions present in these parameters, but find f(R) gravity an inadequate explanation.
The 21cm power spectrum and the shapes of non-Gaussianity
Chongchitnan, Sirichai
2013-03-01
We consider how measurements of the 21cm radiation from the epoch of reionization (z = 8?12) can constrain the amplitudes of various 'shapes' of primordial non-Gaussianity. The limits on these shapes, each parametrized by the non-linear parameter f{sub NL}, can reveal whether the physics of inflation is more complex than the standard single-field, slow-roll scenario. In this work, we quantify the effects of the well-known local, equilateral, orthogonal and folded types of non-Gaussianities on the 21cm power spectrum, which is expected to be measured by upcoming radio arrays such as the Square-Kilometre Array (SKA). We also assess the prospects of the SKA in constraining these non-Gaussianities, and found constraints that are comparable with those from cosmic-microwave-background experiments such as Planck. We show that the limits on various f{sub NL} can be tightened to O(1) using a radio array with a futuristic but realistic set of specifications.
Power spectrum analysis of ionospheric fluctuations with the Murchison Widefield Array
Loi, Shyeh Tjing; Murphy, Tara; Cairns, Iver H; Bell, Martin; Hurley-Walker, Natasha; Morgan, John; Lenc, Emil; Offringa, A R; Feng, L; Hancock, P J; Kaplan, D L; Kudryavtseva, N; Bernardi, G; Bowman, J D; Briggs, F; Cappallo, R J; Corey, B E; Deshpande, A A; Emrich, D; Gaensler, B M; Goeke, R; Greenhill, L J; Hazelton, B J; Johnston-Hollitt, M; Kasper, J C; Kratzenberg, E; Lonsdale, C J; Lynch, M J; McWhirter, S R; Mitchell, D A; Morales, M F; Morgan, E; Oberoi, D; Ord, S M; Prabu, T; Rogers, A E E; Roshi, A; Shankar, N Udaya; Srivani, K S; Subrahmanyan, R; Tingay, S J; Waterson, M; Wayth, R B; Webster, R L; Whitney, A R; Williams, A; Williams, C L
2015-01-01
Low-frequency, wide field-of-view (FoV) radio telescopes such as the Murchison Widefield Array (MWA) enable the ionosphere to be sampled at high spatial completeness. We present the results of the first power spectrum analysis of ionospheric fluctuations in MWA data, where we examined the position offsets of radio sources appearing in two datasets. The refractive shifts in the positions of celestial sources are proportional to spatial gradients in the electron column density transverse to the line of sight. These can be used to probe plasma structures and waves in the ionosphere. The regional (10-100 km) scales probed by the MWA, determined by the size of its FoV and the spatial density of radio sources (typically thousands in a single FoV), complement the global (100-1000 km) scales of GPS studies and local (0.01-1 km) scales of radar scattering measurements. Our data exhibit a range of complex structures and waves. Some fluctuations have the characteristics of travelling ionospheric disturbances (TIDs), whi...
Campbell, Sheldon Scott
2012-10-19
A new formalism is presented for calculating the mean intensity spectrum and angular power spectrum of gamma-rays or neutrinos from extragalactic annihilating dark matter, taking into account the dependence of the relative ...
Koch, Christof
The Journal of Neuroscience, May 1994, 14(5): 2870-2892 Power Spectrum Analysis of Bursting CellsSI distribution and the power spectrum of the vast majority of bursting cells are compatible with the notion, 1992) as well as via bursting cells (Cattaneo et al., 1981 a; Bonds, 1992). We investigate the temporal
Newsome, William
The Journal of Neuroscience, May 1994, 74(5): 2870-2892 Power Spectrum Analysis of Bursting Cells distribution and the power spectrum of the vast majority of bursting cells are compatible with the notion, 1992) as well as via bursting cells (Cattaneo et al., 1981 a; Bonds, 1992). We investigate the temporal
P. A. Sturrock; J. D. Scargle
2006-06-20
The purpose of this article is to carry out a power-spectrum analysis (based on likelihood methods) of the Super-Kamiokande 5-day dataset that takes account of the asymmetry in the error estimates. Whereas the likelihood analysis involves a linear optimization procedure for symmetrical error estimates, it involves a nonlinear optimization procedure for asymmetrical error estimates. We find that for most frequencies there is little difference between the power spectra derived from analyses of symmetrized error estimates and from asymmetrical error estimates. However, this proves not to be the case for the principal peak in the power spectra, which is found at 9.43 yr-1. A likelihood analysis which allows for a "floating offset" and takes account of the start time and end time of each bin and of the flux estimate and the symmetrized error estimate leads to a power of 11.24 for this peak. A Monte Carlo analysis shows that there is a chance of only 1% of finding a peak this big or bigger in the frequency band 1 - 36 yr-1 (the widest band that avoids artificial peaks). On the other hand, an analysis that takes account of the error asymmetry leads to a peak with power 13.24 at that frequency. A Monte Carlo analysis shows that there is a chance of only 0.1% of finding a peak this big or bigger in that frequency band 1 - 36 yr-1. From this perspective, power spectrum analysis that takes account of asymmetry of the error estimates gives evidence for variability that is significant at the 99.9% level. We comment briefly on an apparent discrepancy between power spectrum analyses of the Super-Kamiokande and SNO solar neutrino experiments.
Roy, A; Arzoumanian, D; Peretto, N; Palmeirim, P; Konyves, V; Schneider, N; Benedettini, M; Di Francesco, J; Elia, D; Hill, T; Ladjelate, B; Louvet, F; Motte, F; Pezzuto, S; Schisano, E; Shimajiri, Y; Spinoglio, L; Ward-Thompson, D; White, G
2015-01-01
Two major features of the prestellar CMF are: 1) a broad peak below 1 Msun, presumably corresponding to a mean gravitational fragmentation scale, and 2) a characteristic power-law slope, very similar to the Salpeter slope of the stellar initial mass function (IMF) at the high-mass end. While recent Herschel observations have shown that the peak of the prestellar CMF is close to the thermal Jeans mass in marginally supercritical filaments, the origin of the power-law tail of the CMF/IMF at the high-mass end is less clear. Inutsuka (2001) proposed a theoretical scenario in which the origin of the power-law tail can be understood as resulting from the growth of an initial spectrum of density perturbations seeded along the long axis of filaments by interstellar turbulence. Here, we report the statistical properties of the line-mass fluctuations of filaments in nearby molecular clouds observed with Herschel using a 1-D power spectrum analysis. The observed filament power spectra were fitted by a power-law function...
A power line impedance spectrum analyzer using real-time digital signal processing
Margolis, Michael G
1993-01-01
Power distribution system impedance as seen by power converters and other non-linear loads is important for the determination of harmonic current injection and propagation caused by these loads. This thesis presents a real-time power line impedance...
Power Spectrum of the density of cold atomic gas in the Galaxy towards Cas A and Cygnus A
A. A. Deshpande; K. S. Dwarakanath; W. M. Goss
2000-07-25
We have obtained the power spectral description of the density and opacity fluctuations of the cold HI gas in the Galaxy towards Cas A, and Cygnus A. We have employed a method of deconvolution, based on CLEAN, to estimate the true power spectrum of optical depth of cold HI gas from the observed distribution, taking into account the finite extent of the background source and the incomplete sampling of optical depth over the extent of the source. We investigate the nature of the underlying spectrum of density fluctuations in the cold HI gas which would be consistent with that of the observed HI optical depth fluctuations. These power spectra for the Perseus arm towards Cas A, and for the Outer arm towards Cygnus A have a slope of 2.75 +/- 0.25 (3sigma error). The slope in the case of the Local arm towards Cygnus A is 2.5, and is significantly shallower in comparison. The linear scales probed here range from 0.01 to 3 pc. We discuss the implications of our results, the non-Kolmogorov nature of the spectrum, and the observed HI opacity variations on small transverse scales.
Siegel, David A.
The effect of surface irradiance on the absorption spectrum of chromophoric dissolved organic 2012 Keywords: Marine CDOM Solar irradiation Surface Photobleaching Photoproduction a b s t r a c Oceans were irradiated over several days with full-spectrum light under a solar simulator at in situ
James, F.; Beidas, H.; Fox, R.
2003-01-01
The standardization of the power market structure and transmission access rules will result in new rules for dealing with the transmission systems. Furthermore, transmission system limitations and market inadequacies will have a significant impact...
Not Available
2010-12-01
When power production at The Geysers geothermal power complex began to falter, the National Renewable Energy Laboratory (NREL) stepped in, developing advanced condensing technology that dramatically boosted production efficiency - and making a major contribution to the effective use of geothermal power. NREL developed advanced direct-contact condenser (ADCC) technology to condense spent steam more effectively, improving power production efficiency in Unit 11 by 5%.
Souradeep, Tarun
Saha,1,2,3,4, Pankaj Jain,4, and Tarun Souradeep1,x 1 IUCAA, Post Bag 4, Ganeshkhind, Pune-411007 of CMB power spectrum estimation was proposed by Saha et al. 2006. This methodology demonstrates
On the Feasibility of Low-Power Secondary Access to 960-1215 MHz Aeronautical Spectrum
Obregon, Evanny; Zander, Jens
2012-01-01
In this paper, we analyze the feasibility of short range indoor communication using secondary spectrum access to the 960-1215 MHz band, primarily allocated to the distance measuring equipment (DME) system for aeronautical navigation. We propose a practical secondary sharing scheme based on a combination of geo-location databases and spectrum sensing. Since the DME system performs a safety-of-life function, protection from harmful interference becomes extremely critical. Secondary users estimate the propagation loss and employ an individual interference threshold to control the aggregate interference. We examine the feasibility of large scale secondary access in terms of the transmission probability (of the secondary users) that keeps the probability of harmful interference below a given limit. Delays in the database update and uncertainties in the estimated propagation losses due to fading affect the feasibility of the secondary access. We propose a cumulant-based approximation of the probability distribution...
A model for the non-universal power-law of the solar wind sub-ion scale magnetic spectrum
Passot, T
2015-01-01
A phenomenological turbulence model for kinetic Alfv\\'en waves in a magnetized collisionless plasma, able to reproduce the non-universal power-law spectra observed at the sub-ion scales in the solar wind and the terrestrial magnetosphere, is presented. Nonlocal interactions are retained, and critical balance, characteristic of a strong turbulence regime, establishes dynamically as the cascade proceeds. The process of temperature homogenization along distorted magnetic field lines, induced by Landau damping, affects the turbulence transfer time and results in a steepening of the sub-ion power-law spectrum of critically-balanced turbulence, whose exponent is in particular sensitive to the ratio between the Alfv\\'en wave period and the nonlinear timescale.
Detection of periodic signatures in the solar power spectrum. On the track of l=1 gravity modes
R. A. Garcia; S. Turck-Chieze; S. J. Jimenez-Reyes; J. Ballot; P. L. Palle; A. Eff-Darwich; S. Mathur; J. Provost
2006-11-27
In the present work we show robust indications of the existence of g modes in the Sun using 10 years of GOLF data. The present analysis is based on the exploitation of the collective properties of the predicted low-frequency (25 to 140 microHz) g modes: their asymptotic nature, which implies a quasi equidistant separation of their periods for a given angular degree (l). The Power Spectrum (PS) of the Power Spectrum Density (PSD), reveals a significant structure indicating the presence of features (peaks) in the PSD with near equidistant periods corresponding to l=1 modes in the range n=-4 to n=-26. The study of its statistical significance of this feature was fully undertaken and complemented with Monte Carlo simulations. This structure has a confidence level better than 99.86% not to be due to pure noise. Furthermore, a detailed study of this structure suggests that the gravity modes have a much more complex structure than the one initially expected (line-widths, magnetic splittings...). Compared to the latest solar models, the obtained results tend to favor a solar core rotating significantly faster than the rest of the radiative zone. In the framework of the Phoebus group, we have also applied the same methodology to other helioseismology instruments on board SoHO and ground based networks.
Review of Methods of Power-Spectrum Analysis as Applied to Super-Kamiokande Solar Neutrino Data
P. A. Sturrock
2004-08-02
To help understand why different published analyses of the Super-Kamiokande solar neutrino data arrive at different conclusions, we have applied six different methods to a standardized problem. The key difference between the various methods rests in the amount of information that each processes. A Lomb-Scargle analysis that uses the mid times of the time bins and ignores experimental error estimates uses the least information. A likelihood analysis that uses the start times, end times, and mean live times, and takes account of the experimental error estimates, makes the greatest use of the available information. We carry out power-spectrum analyses of the Super-Kamiokande 5-day solar neutrino data, using each method in turn, for a standard search band (0 to 50 yr-1). For each method, we also carry out a fixed number (10,000) of Monte-Carlo simulations for the purpose of estimating the significance of the leading peak in each power spectrum. We find that, with one exception, the results of these calculations are compatible with those of previously published analyses. (We are unable to replicate Koshio's recent results.) We find that the significance of the peaks at 9.43 yr-1 and at 43.72 yr-1 increases progressively as one incorporates more information into the analysis procedure.
Not Available
2010-12-01
Parabolic trough technology is the most mature of the various concentrating solar power (CSP) options. But scientists at the National Renewable Energy Laboratory (NREL) continue to make advances on trough systems through innovative research on various components in industrial partnerships with Acciona Solar Power, SkyFuel, Schott Solar, and others. The results are leading to improved system efficiencies and lower costs for CSP plants.
Ade, P. A. R.; Akiba, Y.; Hasegawa, M.; Anthony, A. E.; Halverson, N. W.; Arnold, K.; Atlas, M.; Barron, D.; Boettger, D.; Elleflot, T.; Feng, C.; Borrill, J.; Errard, J.; Chapman, S.; Chinone, Y.; Flanigan, D.; Dobbs, M.; Gilbert, A.; Fabbian, G.; Collaboration: Polarbear Collaboration; and others
2014-10-20
We report a measurement of the B-mode polarization power spectrum in the cosmic microwave background (CMB) using the POLARBEAR experiment in Chile. The faint B-mode polarization signature carries information about the universe's entire history of gravitational structure formation, and the cosmic inflation that may have occurred in the very early universe. Our measurement covers the angular multipole range 500 < ? < 2100 and is based on observations of an effective sky area of 25 deg{sup 2} with 3.'5 resolution at 150 GHz. On these angular scales, gravitational lensing of the CMB by intervening structure in the universe is expected to be the dominant source of B-mode polarization. Including both systematic and statistical uncertainties, the hypothesis of no B-mode polarization power from gravitational lensing is rejected at 97.2% confidence. The band powers are consistent with the standard cosmological model. Fitting a single lensing amplitude parameter A{sub BB} to the measured band powers, A{sub BB}=1.12±0.61(stat){sub ?0.12}{sup +0.04}(sys)±0.07(multi), where A{sub BB} = 1 is the fiducial WMAP-9 ?CDM value. In this expression, 'stat' refers to the statistical uncertainty, 'sys' to the systematic uncertainty associated with possible biases from the instrument and astrophysical foregrounds, and 'multi' to the calibration uncertainties that have a multiplicative effect on the measured amplitude A{sub BB}.
Park, Hyunbae; Shapiro, Paul R; Koda, Jun; Mao, Yi
2015-01-01
Cosmological transverse momentum fields, whose directions are perpendicular to Fourier wave vectors, induce temperature anisotropies in the cosmic microwave background via the kinetic Sunyaev-Zeldovich (kSZ) effect. The transverse momentum power spectrum contains the four-point function of density and velocity fields, $\\langle\\delta\\delta v v\\rangle$. In the post-reionization epoch, nonlinear effects dominate in the power spectrum. We use perturbation theory and cosmological $N$-body simulations to calculate this nonlinearity. We derive the next-to-leading order expression for the power spectrum with a particular emphasis on the connected term that has been ignored in the literature. While the contribution from the connected term on small scales ($k>0.1~h~\\rm{Mpc}^{-1}$) is subdominant relative to the unconnected term, we find that its contribution to the kSZ power spectrum at $\\ell = 3000$ at $z6$) by twenty percent. The power spectrum of transverse momentum on large scales is expected to scale as $k^2$ as a...
A Gamma-Ray Burst/Pulsar for Cosmic-Ray Positrons with a Dark Matter-like Spectrum
Kunihito Ioka
2010-06-15
We propose that a nearby gamma-ray burst (GRB) or GRB-like (old, single and short-lived) pulsar/supernova remnant/microquasar about 10^{5-6} years ago may be responsible for the excesses of cosmic-ray positrons and electrons recently observed by the PAMELA, ATIC/PPB-BETS, Fermi and HESS experiments. We can reproduce the smooth Fermi/HESS spectra as well as the spiky ATIC/PPB-BETS spectra. The spectra have a sharp cutoff that is similar to the dark matter predictions, sometimes together with a line (not similar), since higher energy cosmic-rays cool faster where the cutoff/line energy marks the source age. A GRB-like astrophysical source is expected to have a small but finite spread in the cutoff/line as well as anisotropy in the cosmic-ray and diffuse gamma-ray flux, providing a method for the Fermi and future CALET experiments to discriminate between dark matter and astrophysical origins.
Design of a Low Power, Fast-Spectrum, Liquid-Metal Cooled Surface Reactor System
Marcille, T. F.; Poston, D. I.; Kapernick, R. J. [Nuclear Systems Design Group, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Dixon, D. D. [Nuclear Systems Design Group, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Department of Nuclear Engineering, North Carolina State University, Raleigh, NC 27695 (United States); Fischer, G. A. [Nuclear Systems Design Group, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109 (United States); Doherty, S. P. [Nuclear Systems Design Group, Los Alamos National Laboratory, Los Alamos, NM 87545 (United States); Department of Engineering, Trinity College, Hartford, CT 06106 (United States)
2006-01-20
In the current 2005 US budget environment, competition for fiscal resources make funding for comprehensive space reactor development programs difficult to justify and accommodate. Simultaneously, the need to develop these systems to provide planetary and deep space-enabling power systems is increasing. Given that environment, designs intended to satisfy reasonable near-term surface missions, using affordable technology-ready materials and processes warrant serious consideration. An initial lunar application design incorporating a stainless structure, 880 K pumped NaK coolant system and a stainless/UO2 fuel system can be designed, fabricated and tested for a fraction of the cost of recent high-profile reactor programs (JIMO, SP-100). Along with the cost reductions associated with the use of qualified materials and processes, this design offers a low-risk, high-reliability implementation associated with mission specific low temperature, low burnup, five year operating lifetime requirements.
P. A. Sturrock; J. B. Buncher; E. Fischbach; J. T. Gruenwald; D. Javorsek II; J. H. Jenkins; R. H. Lee; J. J. Mattes; J. R. Newport
2010-10-11
Evidence for an anomalous annual periodicity in certain nuclear decay data has led to speculation concerning a possible solar influence on nuclear processes. We have recently analyzed data concerning the decay rates of Cl-36 and Si-32, acquired at the Brookhaven National Laboratory (BNL), to search for evidence that might be indicative of a process involving solar rotation. Smoothing of the power spectrum by weighted-running-mean analysis leads to a significant peak at frequency 11.18/yr, which is lower than the equatorial synodic rotation rates of the convection and radiative zones. This article concerns measurements of the decay rates of Ra-226 acquired at the Physikalisch-Technische Bundesanstalt (PTB) in Germany. We find that a similar (but not identical) analysis yields a significant peak in the PTB dataset at frequency 11.21/yr, and a peak in the BNL dataset at 11.25/yr. The change in the BNL result is not significant since the uncertainties in the BNL and PTB analyses are estimated to be 0.13/yr and 0.07/yr, respectively. Combining the two running means by forming the joint power statistic leads to a highly significant peak at frequency 11.23/yr. We comment briefly on the possible implications of these results for solar physics and for particle physics.
John M. Dickey; N. M. McClure-Griffiths; Snezana Stanimirovic; B. M. Gaensler; A. J. Green
2001-07-31
Using data from the Southern Galactic Plane Survey we have measured the spatial power spectrum of the interstellar neutral atomic hydrogen in the fourth Galactic quadrant. This function shows the same power law behavior that has been found for H I in the second quadrant of the Milky Way and in the Magellanic Clouds, with the same slope. When we average over velocity intervals broader than the typical small-scale velocity dispersion, we find that the slope steepens, from approx. -3 to -4 for the warm gas, as predicted by theories of interstellar turbulence if the column density fluctuations are dominated by variations in the gas density on small spatial scales. The cool gas shows a different increase of slope, that suggests that it is in the regime of turbulence dominated by fluctuations in the velocity field. Overall, these results confirm that the small scale structure and motions in the neutral atomic medium are well described by a turbulent cascade of kinetic energy.
Bilayer Polymer Solar Cells with Improved Power Conversion Efficiency and Enhanced Spectrum Coverage
Kekuda, Dhananjaya [Department of Physics, Manipal Institute of Technology, Manipal University, Manipal, India 576 104 (India); Chu, Chih-Wei [Research Center for Applied Science, Academia Sinica, Taipei, Taiwan 300 13 (China)
2011-10-20
We demonstrate the construction of an efficient bilayer polymer solar cell comprising of Poly(3-hexylthiophene)(P3HT) as a p-type semiconductor and asymmetric fullerene (C{sub 70}) as n-type counterparts. The bilayer configuration was very efficient compared to the individual layer performance and it behaved like a regular p-n junction device. The photovoltaic characteristic of the bilayers were studied under AM 1.5 solar radiation and the optimized device parameters are the following: Voc = 0.5V, Jsc = 10.1 mA/cm{sup 2}, FF = 0.60 and power conversion efficiency of 3.6 %. A high fill factor of {approx}0.6 was achieved, which is only slightly reduced at very intense illumination. Balanced mobility between p-and n-layers is achieved which is essential for achieving high device performance. Correlation between the crystallinity, morphology and the transport properties of the active layers is established. The External quantum efficiency (EQE) spectral distribution of the bilayer devices with different processing solvents correlates well with the trends of short circuit current densities (J{sub sc}) measured under illumination. Efficiency of the bilayer devices with rough P3HT layer was found to be about 3 times higher than those with a planar P3HT surface. Hence it is desirable to have a larger grains with a rough surface of P3HT layer for providing larger interfacial area for the exciton dissociation.
Cerdeno, D G; Robles, S
2015-01-01
We study spectral features in the gamma-ray emission from dark matter (DM) annihilation in the Next-to-Minimal Supersymmetric Standard Model (NMSSM), with either neutralino or right-handed (RH) sneutrino DM. We perform a series of scans over the NMSSM parameter space, compute the DM annihilation cross section into two photons and the contribution of box-shaped features, and compare them with the limits derived from the Fermi-LAT search for gamma-ray lines using the latest Pass 8 data. We implement the LHC bounds on the Higgs sector and on the masses of supersymmetric particles as well as the constraints on low-energy observables. We also consider the recent upper limits from the Fermi-LAT satellite on the continuum gamma-ray emission from dwarf spheroidal galaxies (dSphs). We show that in the case of the RH sneutrino the constraint on gamma-ray spectral features can be more stringent than the dSphs bounds. This is due to the Breit-Wigner enhancement near the ubiquitous resonances with a CP even Higgs and the ...
Fast Neutron Spectrum Potassium Worth for Space Power Reactor Design Validation
Bess, John D.; Marshall, Margaret A.; Briggs, J. Blair; Tsiboulia, Anatoli; Rozhikhin, Yevgeniy; Mihalczo, John T.
2015-03-01
A variety of critical experiments were constructed of enriched uranium metal (oralloy ) during the 1960s and 1970s at the Oak Ridge Critical Experiments Facility (ORCEF) in support of criticality safety operations at the Y-12 Plant. The purposes of these experiments included the evaluation of storage, casting, and handling limits for the Y-12 Plant and providing data for verification of calculation methods and cross-sections for nuclear criticality safety applications. These included solid cylinders of various diameters, annuli of various inner and outer diameters, two and three interacting cylinders of various diameters, and graphite and polyethylene reflected cylinders and annuli. Of the hundreds of delayed critical experiments, one was performed that consisted of uranium metal annuli surrounding a potassium-filled, stainless steel can. The outer diameter of the annuli was approximately 13 inches (33.02 cm) with an inner diameter of 7 inches (17.78 cm). The diameter of the stainless steel can was 7 inches (17.78 cm). The critical height of the configurations was approximately 5.6 inches (14.224 cm). The uranium annulus consisted of multiple stacked rings, each with radial thicknesses of 1 inch (2.54 cm) and varying heights. A companion measurement was performed using empty stainless steel cans; the primary purpose of these experiments was to test the fast neutron cross sections of potassium as it was a candidate for coolant in some early space power reactor designs.The experimental measurements were performed on July 11, 1963, by J. T. Mihalczo and M. S. Wyatt (Ref. 1) with additional information in its corresponding logbook. Unreflected and unmoderated experiments with the same set of highly enriched uranium metal parts were performed at the Oak Ridge Critical Experiments Facility in the 1960s and are evaluated in the International Handbook for Evaluated Criticality Safety Benchmark Experiments (ICSBEP Handbook) with the identifier HEU MET FAST 051. Thin graphite reflected (2 inches or less) experiments also using the same set of highly enriched uranium metal parts are evaluated in HEU MET FAST 071. Polyethylene-reflected configurations are evaluated in HEU-MET-FAST-076. A stack of highly enriched metal discs with a thick beryllium top reflector is evaluated in HEU-MET-FAST-069, and two additional highly enriched uranium annuli with beryllium cores are evaluated in HEU-MET-FAST-059. Both detailed and simplified model specifications are provided in this evaluation. Both of these fast neutron spectra assemblies were determined to be acceptable benchmark experiments. The calculated eigenvalues for both the detailed and the simple benchmark models are within ~0.26 % of the benchmark values for Configuration 1 (calculations performed using MCNP6 with ENDF/B-VII.1 neutron cross section data), but under-calculate the benchmark values by ~7s because the uncertainty in the benchmark is very small: ~0.0004 (1s); for Configuration 2, the under-calculation is ~0.31 % and ~8s. Comparison of detailed and simple model calculations for the potassium worth measurement and potassium mass coefficient yield results approximately 70 – 80 % lower (~6s to 10s) than the benchmark values for the various nuclear data libraries utilized. Both the potassium worth and mass coefficient are also deemed to be acceptable benchmark experiment measurements.
D. G. Cerdeno; M. Peiro; S. Robles
2015-07-31
We study spectral features in the gamma-ray emission from dark matter (DM) annihilation in the Next-to-Minimal Supersymmetric Standard Model (NMSSM), with either neutralino or right-handed (RH) sneutrino DM. We perform a series of scans over the NMSSM parameter space, compute the DM annihilation cross section into two photons and the contribution of box-shaped features, and compare them with the limits derived from the Fermi-LAT search for gamma-ray lines using the latest Pass 8 data. We implement the LHC bounds on the Higgs sector and on the masses of supersymmetric particles as well as the constraints on low-energy observables. We also consider the recent upper limits from the Fermi-LAT satellite on the continuum gamma-ray emission from dwarf spheroidal galaxies (dSphs). We show that in the case of the RH sneutrino the constraint on gamma-ray spectral features can be more stringent than the dSphs bounds. This is due to the Breit-Wigner enhancement near the ubiquitous resonances with a CP even Higgs and the contribution of scalar and pseudoscalar Higgs final states to box-shaped features. By contrast, for neutralino DM, the di-photon final state is only enhanced in the resonance with a $Z$ boson and box-shaped features are even more suppressed. Therefore, the observation of spectral features could constitute a discriminating factor between both models. In addition, we compare our results with direct DM searches, including the SuperCDMS and LUX limits on the elastic DM-nucleus scattering cross section and show that some of these scenarios would be accessible to next generation experiments. Thus, our findings strengthen the idea of complementarity among distinct DM search strategies.
P. A. Sturrock; D. O. Caldwell; J. D. Scargle; M. S. Wheatland
2005-08-08
There have been conflicting claims as to whether or not power-spectrum analysis of the Super-Kamiokande solar neutrino data yields evidence of variability. Comparison of these claims is complicated by the fact that the relevant articles may use different datasets, different methods of analysis, and different procedures for significance estimation. The purpose of this article is to clarify the role of power spectrum analysis. To this end, we analyze only the Super-Kamiokande 5-day dataset, and we use a standard procedure for significance estimation proposed by the Super-Kamiokande collaboration. We then analyze this dataset, with this method of significance estimation, using six methods of power spectrum analysis. We find that the significance of the principal peak in the power spectrum (that at 9.43 yr-1with a depth of modulation of 7%) shows a clear correlation with the amount and relevance of the information being processed, as would be expected if there were a real signal in the data. The significance level reaches 99.3% for one method of analysis. We discuss, in terms of sub-dominant processes, possible neutrino-physics interpretations of the apparent variability of the Super-Kamiokande measurements, and we suggest steps that could be taken to resolve the question of variability of the solar neutrino flux.
Barradale, Merrill Jones
2010-01-01
Renewable Energy Power Purchase Agreements. ” Journal ofit is the dynamic of power purchase agreement negotiationsbuy and sell sides of power purchase agreements (PPA), and
Barradale, Merrill Jones
2010-01-01
Chen. (2007). “Should a coal-fired power plant be replacedof Regulatory Uncertainty for Coal-Fired Power Plants. ”in alternative coal-fired power plant technologies. ” Energy
Barradale, Merrill Jones
2010-01-01
2007). “Should a coal-fired power plant be replaced orUncertainty for Coal-Fired Power Plants. ” Environmentalin alternative coal-fired power plant technologies. ” Energy
Dodelson, Scott; /Fermilab /Chicago U., Astron. Astrophys. Ctr. /Northwestern U.; Shapiro, Charles; /Chicago U. /KICP, Chicago; White, Martin J.; /UC, Berkeley, Astron.
2005-08-01
Measurements of ellipticities of background galaxies are sensitive to the reduced shear, the cosmic shear divided by (1-{kappa}) where {kappa} is the projected density field. They compute the difference between shear and reduced shear both analytically and with simulations. The difference becomes more important an smaller scales, and will impact cosmological parameter estimation from upcoming experiments. A simple recipe is presented to carry out the required correction.
Dark matter, a new proof of the predictive power of general relativity
Stéphane Le Corre
2015-06-30
Without observational or theoretical modifications, Newtonian and general relativity seem to be unable to explain gravitational behavior of large structure of the universe. The assumption of dark matter solves this problem without modifying theories. But it implies that most of the matter in the universe must be unobserved matter. Another solution is to modify gravitation laws. In this article, we study a third way that doesn't modify gravitation neither matter's distribution, by using a new physical assumption on the clusters. Compare with Newtonian gravitation, general relativity (in its linearized approximation) leads to add a new component without changing the gravity field. As already known, this component for galaxies is too small to explain dark matter. But we will see that the galaxies' clusters can generate a significant component and embed large structure of universe. We show that the magnitude of this embedding component is small enough to be in agreement with current experimental results, undetectable at our scale, but detectable at the scale of the galaxies and explain dark matter, in particular the rotation speed of galaxies, the rotation speed of dwarf satellite galaxies, the expected quantity of dark matter inside galaxies and the expected experimental values of parameters $\\Omega$\\_dm of dark matter measured in CMB. This solution implies testable consequences that differentiate it from other theories: decreasing dark matter with the distance to the cluster's center, large quantity of dark matter for galaxies close to the cluster's center, isolation of galaxies without dark matter, movement of dwarf satellite galaxies in planes close to the supergalactic plane, close orientations of spin's vectors of two close clusters, orientation of nearly all the spin's vector of galaxies of a same cluster in a same half-space, existence of very rare galaxies with two portions of their disk that rotate in opposite directions...
S. T. Myers; C. R. Contaldi; J. R. Bond; U. -L. Pen; D. Pogosyan; S. Prunet; J. L. Sievers; B. S. Mason; T. J. Pearson; A. C. S. Readhead; M. C. Shepherd
2002-05-23
We describe an algorithm for the extraction of the angular power spectrum of an intensity field, such as the cosmic microwave background (CMB), from interferometer data. This new method, based on the gridding of interferometer visibilities in the aperture plane followed by a maximum likelihood solution for bandpowers, is much faster than direct likelihood analysis of the visibilities, and deals with foreground radio sources, multiple pointings, and differencing. The gridded aperture-plane estimators are also used to construct Wiener-filtered images using the signal and noise covariance matrices used in the likelihood analysis. Results are shown for simulated data. The method has been used to determine the power spectrum of the cosmic microwave background from observations with the Cosmic Background Imager, and the results are given in companion papers.
Ana Achucarro; Vicente Atal; Bin Hu; Pablo Ortiz; Jesus Torrado
2015-10-16
We continue the study of mild transient reductions in the speed of sound of the adiabatic mode during inflation, of their effect on the primordial power spectrum and bispectrum, and of their detectability in the Cosmic Microwave Background (CMB). We focus on the regime of \\emph{moderately sharp} mild reductions in the speed of sound during uninterrupted slow-roll inflation, a theoretically well motivated and self-consistent regime that admits an effective single-field description. The signatures on the power spectrum and bispectrum were previously computed using a slow-roll Fourier transform (SRFT) approximation, and here we compare it with generalized slow-roll (GSR) and in-in methods, for which we derive new formulas that account for moderately sharp features. The agreement between them is excellent, and also with the power spectrum obtained from the numerical solution to the equation of motion. We show that, in this regime, the SRFT approximation correctly captures with simplicity the effect of higher derivatives of the speed of sound in the mode equation, and makes manifest the correlations between power spectrum and bispectrum features. In a previous paper we reported hints of these correlations in the Planck data and here we perform several consistency checks and further analyses of the best fits, such as polarization and local significance at different angular scales. For the data analysis, we show the excellent agreement between the CLASS and CAMB Boltzmann codes. Our results confirm that the theoretical framework is consistent, and they suggest that the predicted correlations are robust enough to be searched for in CMB and Large Scale Structure (LSS) surveys.
Barradale, Merrill Jones
2010-01-01
on U.S. Wind Power Installation, Cost, and Performanceon U.S. Wind Power Installation, Cost, and Performancenot returned). Higher wind supply costs; Greater reliance on
Peter A. Sturrock; Alexander G. Parkhomov; Ephraim Fischbach; Jere H. Jenkins
2012-03-21
This article presents a power-spectrum analysis of 2,350 measurements of the $^{90}$Sr/$^{90}$Y decay process acquired over the interval 4 August 2002 to 6 February 2009 at the Lomonosov Moscow State University (LMSU). As we have found for other long sequences of decay measurements, the power spectrum is dominated by a very strong annual oscillation. However, we also find a set of low-frequency peaks, ranging from 0.26 year$^{-1}$ to 3.98 year$^{-1}$, which are very similar to an array of peaks in a power spectrum formed from Mt Wilson solar diameter measurements. The Mt Wilson measurements have been interpreted in terms of r-mode oscillations in a region where the sidereal rotation frequency is 12.08 year$^{-1}$. We find that the LMSU measurements may also be attributed to the same type of r-mode oscillations in a solar region with the same sidereal rotation frequency. We propose that these oscillations occur in an inner tachocline that separates the radiative zone from a more slowly rotating solar core.
Sturrock, Peter A; Fischbach, Ephraim; Jenkins, Jere H
2012-01-01
This article presents a power-spectrum analysis of 2,350 measurements of the $^{90}$Sr/$^{90}$Y decay process acquired over the interval 4 August 2002 to 6 February 2009 at the Lomonosov Moscow State University (LMSU). As we have found for other long sequences of decay measurements, the power spectrum is dominated by a very strong annual oscillation. However, we also find a set of low-frequency peaks, ranging from 0.26 year$^{-1}$ to 3.98 year$^{-1}$, which are very similar to an array of peaks in a power spectrum formed from Mt Wilson solar diameter measurements. The Mt Wilson measurements have been interpreted in terms of r-mode oscillations in a region where the sidereal rotation frequency is 12.08 year$^{-1}$. We find that the LMSU measurements may also be attributed to the same type of r-mode oscillations in a solar region with the same sidereal rotation frequency. We propose that these oscillations occur in an inner tachocline that separates the radiative zone from a more slowly rotating solar core.
Dark matter, a new proof of the predictive power of general relativity
Corre, Stéphane Le
2015-01-01
Without observational or theoretical modifications, Newtonian and general relativity seem to be unable to explain gravitational behavior of large structure of the universe. The assumption of dark matter solves this problem without modifying theories. But it implies that most of the matter in the universe must be unobserved matter. Another solution is to modify gravitation laws. In this article, we study a third way that does not modify gravitation of general relativity and not modify the matter's distribution, by using gravitomagnetism in a new physical context. Compare with Newtonian gravitation, it leads to add a new component without changing the gravity field. As already known, we retrieve that this new component is generally small enough to be undetectable. But we will see that the galaxies clusters can generate a significant component and embed large structure of universe. We show that the magnitude of this embedding component is once again small enough to be in agreement with current experimental resul...
Cosmology with matter diffusion
Calogero, Simone; Velten, Hermano E-mail: velten@cce.ufes.br
2013-11-01
We construct a viable cosmological model based on velocity diffusion of matter particles. In order to ensure the conservation of the total energy-momentum tensor in the presence of diffusion, we include a cosmological scalar field ? which we identify with the dark energy component of the universe. The model is characterized by only one new degree of freedom, the diffusion parameter ?. The standard ?CDM model can be recovered by setting ? = 0. If diffusion takes place (? > 0) the dynamics of the matter and of the dark energy fields are coupled. We argue that the existence of a diffusion mechanism in the universe may serve as a theoretical motivation for interacting models. We constrain the background dynamics of the diffusion model with Supernovae, H(z) and BAO data. We also perform a perturbative analysis of this model in order to understand structure formation in the universe. We calculate the impact of diffusion both on the CMB spectrum, with particular attention to the integrated Sachs-Wolfe signal, and on the matter power spectrum P(k). The latter analysis places strong constraints on the magnitude of the diffusion mechanism but does not rule out the model.
Condensed Matter Cluster Reactions in LENR Power Cells for a Radical New Type of Space Power Source
Yang Xiaoling; Miley, George H.; Hora, Heinz
2009-03-16
This paper reviews previous theoretical and experimental study on the possibility of nuclear events in multilayer thin film electrodes (Lipson et al., 2004 and 2005; Miley et al., 2007), including the correlation between excess heat and transmutations (Miley and Shrestha, 2003) and the cluster theory that predicts it. As a result of this added understanding of cluster reactions, a new class of electrodes is under development at the University of Illinois. These electrodes are designed to enhance cluster formation and subsequent reactions. Two approaches are under development. The first employs improved loading-unloading techniques, intending to obtain a higher volumetric density of sites favoring cluster formation. The second is designed to create nanostructures on the electrode where the cluster state is formed by electroless deposition of palladium on nickel micro structures. Power units employing these electrodes should offer unique advantages for space applications. This is a fundamental new nuclear energy source that is environmentally compatible with a minimum of radiation involvement, high specific power, very long lifetime, and scalable from micro power to kilowatts.
Dark matter capture in the first stars: a power source and limit on stellar mass
Freese, Katherine; Spolyar, Douglas; Aguirre, Anthony E-mail: dspolyar@physics.ucsc.edu
2008-11-15
The annihilation of weakly interacting massive particles can provide an important heat source for the first (Pop III, 'Pop' standing for 'population') stars, potentially leading to a new phase of stellar evolution known as a 'dark star'. When dark matter (DM) capture via scattering off baryons is included, the luminosity from DM annihilation may dominate over the luminosity due to fusion, depending on the DM density and scattering cross section. The influx of DM due to capture may thus prolong the dark star phase of stellar evolution as long as the ambient DM density is high enough. Comparison of DM luminosity with the Eddington luminosity for the star may constrain the stellar mass of zero-metallicity stars. Alternatively, if sufficiently massive Pop III stars are found, they might be used to bound dark matter properties.
Armendariz-Picon, Cristian; Neelakanta, Jayanth T., E-mail: armen@phy.syr.edu, E-mail: jtneelak@syr.edu [Department of Physics, Syracuse University, Syracuse, NY 13244-1130 (United States)
2014-03-01
If cold dark matter consists of particles, these must be non-interacting and non-relativistic by definition. In most cold dark matter models however, dark matter particles inherit a non-vanishing velocity dispersion from interactions in the early universe, a velocity that redshifts with cosmic expansion but certainly remains non-zero. In this article, we place model-independent constraints on the dark matter temperature to mass ratio, whose square root determines the dark matter velocity dispersion. We only assume that dark matter particles decoupled kinetically while non-relativistic, when galactic scales had not entered the horizon yet, and that their momentum distribution has been Maxwellian since that time. Under these assumptions, using cosmic microwave background and matter power spectrum observations, we place upper limits on the temperature to mass ratio of cold dark matter today (away from collapsed structures). These limits imply that the present cold dark matter velocity dispersion has to be smaller than 54 m/s. Cold dark matter has to be quite cold, indeed.
High-power InGaAs/GaAs quantum-well laser with enhanced broad spectrum of stimulated emission
Wang, Huolei; Yu, Hongyan; Zhou, Xuliang; Kan, Qiang; Yuan, Lijun; Wang, Wei; Pan, Jiaoqing, E-mail: jqpan@semi.ac.cn [Key Laboratory of Semiconductor Materials Science, Institute of Semiconductors, Chinese Academy of Science, Beijing 100083 (China); Chen, Weixi [State Key Lab for Mesoscopic Physics and School of Physics, Peking University, Beijing 100871 (China); Ding, Ying, E-mail: Ying.Ding@glasgow.ac.uk [School of Engineering, University of Glasgow, Glasgow G12 8LT (United Kingdom)
2014-10-06
We report the demonstration of an InGaAs/GaAs quantum well (QW) broadband stimulated emission laser with a structure that integrated a GaAs tunnel junction with two QW active regions. The laser exhibits ultrabroad lasing spectral coverage of ?51?nm at a center wavelength of 1060?nm with a total emission power of 790 mW, corresponding to a high average spectral power density of 15.5 mW/nm, under pulsed current conditions. Compared to traditional lasers, this laser with an asymmetric separate-confinement heterostructure shows broader lasing bandwidth and higher spectral power density.
Barradale, Merrill Jones
2010-01-01
L.T. and P. Kraske (2003). “Renewable Energy Power PurchaseInvestments in Renewable Energy: The Role of Policy Design47. Wiser, R. (1997). “Renewable energy finance and project
Barradale, Merrill Jones
2010-01-01
R. (1997). “Renewable energy finance and project ownership:e.g. , “Finance and investment in wind energy in theEnergy Power Purchase Agreements. ” Journal of Structured and Project Finance
Quantum Condensed Matter | Neutron Science | ORNL
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Quantum Condensed Matter SHARE Quantum Condensed Matter Neutron scattering is a uniquely powerful probe for measuring the structure and dynamics of condensed matter. As such it is...
Quantum Condensed Matter | More Science | ORNL
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Quantum Condensed Matter SHARE Quantum Condensed Matter Neutron scattering is a uniquely powerful probe for measuring the structure and dynamics of condensed matter. As such it is...
Agilent AN 1318 Optimizing Spectrum Analyzer
Anlage, Steven
Agilent AN 1318 Optimizing Spectrum Analyzer Measurement Speed Application Note Agilent ESA-E Series #12;2 Why speed matters The measurement speed of your spectrum analyzer can significantly affect for the spectrum analyzer to warm up to make calibrated measurements. · R&D finally receives the new project
Miley, George H. [University of Illinois Urbana-Champaign, NPL Associates 216 Talbot Laboratory 104 S. Wright St. Urbana, IL 61801 (United States); Hora, H. [Department of Theoretical Physics, University of New South Wales Sydney (Australia); Badziak, J.; Wolowski, J. [Institute of Plasma Physics and Laser Microfusion, Warsaw (Poland); Sheng Zhengming [Beijing National Laboratory for CondensedMatter Physics Institute of Physics Chinese Academy of ScienceBeijing 100080 (China); Zhang Jie [School of Computer Sciences, University of Western Sydney, Penrith (Australia); Osman, F. [China Academy of Engineering Physics, Mianyang (China); Zhang Weiyan [Institute of Applied Physics and Computational Mathematics, Beijing (China); Tuhe Xia [Institute of Physics, Academy of Science, Prague (Czech Republic)
2009-03-16
The use of laser-driven Inertial Confinement Fusion (ICF) for space propulsion has been the subject of several earlier conceptual design studies, (see: Orth, 1998; and other references therein). However, these studies were based on older ICF technology using either 'direct' or 'in-direct x-ray driven' type target irradiation. Important new directions have opened for laser ICF in recent years following the development of 'chirped' lasers capable of ultra short pulses with powers of TW up to few PW which leads to the concept of 'fast ignition (FI)' to achieve higher energy gains from target implosions. In a recent publication the authors showed that use of a modified type of FI, termed 'block ignition' (Miley et al., 2008), could meet many of the requirements anticipated (but not then available) by the designs of the Vehicle for Interplanetary Space Transport Applications (VISTA) ICF fusion propulsion ship (Orth, 2008) for deep space missions. Subsequently the first author devised and presented concepts for imbedding high density condensed matter 'clusters' of deuterium into the target to obtain ultra high local fusion reaction rates (Miley, 2008). Such rates are possible due to the high density of the clusters (over an order of magnitude above cryogenic deuterium). Once compressed by the implosion, the yet higher density gives an ultra high reaction rate over the cluster volume since the fusion rate is proportional to the square of the fuel density. Most recently, a new discovery discussed here indicates that the target matrix could be composed of B{sup 11} with proton clusters imbedded. This then makes p-B{sup 11} fusion practical, assuming all of the physics issues such as stability of the clusters during compression are resolved. Indeed, p-B{sup 11} power is ideal for fusion propulsion since it has a minimum of unwanted side products while giving most of the reaction energy to energetic alpha particles which can be directed into an exhaust (propulsion) nozzle. Power plants using p-B{sup 11} have been discussed for such applications before, but prior designs face formidable physics/technology issues, largely overcome with the present approach.
Micro acoustic spectrum analyzer
Schubert, W. Kent; Butler, Michael A.; Adkins, Douglas R.; Anderson, Larry F.
2004-11-23
A micro acoustic spectrum analyzer for determining the frequency components of a fluctuating sound signal comprises a microphone to pick up the fluctuating sound signal and produce an alternating current electrical signal; at least one microfabricated resonator, each resonator having a different resonant frequency, that vibrate in response to the alternating current electrical signal; and at least one detector to detect the vibration of the microfabricated resonators. The micro acoustic spectrum analyzer can further comprise a mixer to mix a reference signal with the alternating current electrical signal from the microphone to shift the frequency spectrum to a frequency range that is a better matched to the resonant frequencies of the microfabricated resonators. The micro acoustic spectrum analyzer can be designed specifically for portability, size, cost, accuracy, speed, power requirements, and use in a harsh environment. The micro acoustic spectrum analyzer is particularly suited for applications where size, accessibility, and power requirements are limited, such as the monitoring of industrial equipment and processes, detection of security intrusions, or evaluation of military threats.
Constraints on particle dark matter from cosmic-ray antiprotons
N. Fornengo; L. Maccione; A. Vittino
2015-01-30
Cosmic-ray antiprotons represent an important channel for dark matter indirect-detection studies. Current measurements of the antiproton flux at the top of the atmosphere and theoretical determinations of the secondary antiproton production in the Galaxy are in good agreement, with no manifest deviation which could point to an exotic contribution in this channel. Therefore, antiprotons can be used as a powerful tool for constraining particle dark matter properties. By using the spectrum of PAMELA data from 50 MV to 180 GV in rigidity, we derive bounds on the dark matter annihilation cross section (or decay rate, for decaying dark matter) for the whole spectrum of dark matter annihilation (decay) channels and under different hypotheses of cosmic-rays transport in the Galaxy and in the heliosphere. For typical models of galactic propagation, the constraints are significantly strong, setting a lower bound on the dark matter mass of a "thermal" relic at about 50-90 GeV for hadronic annihilation channels. These bounds are enhanced to about 150 GeV on the dark matter mass, when large cosmic-rays confinement volumes in the Galaxy are considered, and are reduced to 4-5 GeV for annihilation to light quarks (no bound for heavy-quark production) when the confinement volume is small. Bounds for dark matter lighter than few tens of GeV are due to the low energy part of the PAMELA spectrum, an energy region where solar modulation is relevant: to this aim, we have implemented a detailed solution of the transport equation in the heliosphere, which allowed us not only to extend bounds to light dark matter, but also to determine the uncertainty on the constraints arising from solar modulation modeling. Finally, we estimate the impact of soon-to-come AMS-02 data on the antiproton constraints.
Koushik Ghosh; Probhas Raychaudhuri
2006-06-05
We have used Rayleigh power spectrum analysis of the monthly solar neutrino flux data from (1) SAGE detector during the period from 1st January 1990 to 31st December 2000; (2) SAGE detector during the period from April 1998 to December 2001; (3) GALLEX detector during the period from May 1991 to January 1997; (4) GNO detector during the period from May 1998 to December 2001; (5) GALLEX-GNO detector (combined data) from May 1991 to December 2001 and (6) average of the data from GNO and SAGE detectors during the period from May 1998 to December 2001. (1) exhibits periodicity around 1.3, 4.3, 5.5, 6.3, 7.9, 8.7, 15.9, 18.7, 23.9, 32.9 and 48.7 months. (2) shows periodicity around 1.5, 2.9, 4.5, 10.1 months. For (3) we observe periodicity around 1.7, 18.7 and 26.9 months. For (4) periodicity is seen around 3.5, 5.5, 7.7 and 10.5 months. (5) gives periodicity around 1.7, 18.5, 28.5 and 42.1 months while (6) shows periodicity around 4.3, 6.9, 10.3 and 18.1 months. We have found almost similar periods in the solar flares, sunspot data, solar proton data which indicates that the solar activity cycle may be due to the variable character of nuclear energy generation inside the sun.
Multi-band high efficiency power amplifier
Besprozvanny, Randy-Alexander Randolph
2011-01-01
meter, Agilent E4440A spectrum analyzer, driver amplifier,the power meter and the spectrum analyzer for simultaneous
User's/Programmer's Reference Core Spectrum Analyzer Functions
Anlage, Steven
User's/Programmer's Reference Volume 1 Core Spectrum Analyzer Functions ESA Series Spectrum. For the latest information about Agilent Technologies ESA Spectrum Analyzers, including firmware upgrades and used under license. NOTE If the ESA Spectrum Analyzer experiences a rapid "power down / power up
An Ultimate Target for Dark Matter Searches
Kfir Blum; Yanou Cui; Marc Kamionkowski
2014-12-10
The combination of S-matrix unitarity and the dynamics of thermal freeze-out for massive relic particles (denoted here simply by WIMPs) implies a lower limit on the density of such particles, that provide a (potentially sub-dominant) contribution to dark matter. This then translates to lower limits to the signal rates for a variety of techniques for direct and indirect detection of dark matter. For illustration, we focus on models where annihilation is s-wave dominated. We derive lower limits to the flux of gamma-rays from WIMP annihilation at the Galactic center; direct detection of WIMPs; energetic neutrinos from WIMP annihilation in the Sun; and the effects of WIMPs on the angular power spectrum and frequency spectrum of the cosmic microwave background radiation. The results suggest that a variety of dark-matter-search techniques may provide interesting avenues to seek new physics, even if WIMPs do not constitute all the dark matter. While the limits are quantitatively some distance from the reach of current measurements, they may be interesting for long-range planning exercises.
Changes in the halo formation rates due to features in the primordial spectrum
Hazra, Dhiraj Kumar, E-mail: dhiraj@apctp.org [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211019 (India)
2013-03-01
Features in the primordial scalar power spectrum provide a possible roadway to describe the outliers at the low multipoles in the WMAP data. Apart from the CMB angular power spectrum, these features can also alter the matter power spectrum and, thereby, the formation of the large scale structure. Carrying out a complete numerical analysis, we investigate the effects of primordial features on the formation rates of the halos. We consider a few different inflationary models that lead to features in the scalar power spectrum and an improved fit to the CMB data, and analyze the corresponding imprints on the formation of halos. Performing a Markov Chain Monte Carlo analysis with the WMAP seven year data and the SDSS halo power spectrum from LRG DR7 for the models of our interest, we arrive at the parameter space of the models allowed by the data. We illustrate that, inflationary potentials, such as the quadratic potential with sinusoidal modulations and the axion monodromy model, which generate certain repeated, oscillatory features in the inflationary perturbation spectrum, do not induce a substantial difference in the number density of halos at their best fit values, when compared with, say, a nearly scale invariant spectrum as is generated by the standard quadratic potential. However, we find that the number density and the formation rates of halos change by about 13–22% for halo masses ranging over 10{sup 4}–10{sup 14} M{sub s}un, for potential parameters that lie within 2-? around the best fit values arrived at from the aforesaid joint constraints. We briefly discuss the implications of our results.
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfateSciTechtail.TheoryTuesday, August 10, 20102016 News BelowAskedAIKENALSDoctoralALSALSALS Spectrum
The First Billion Years of a Warm Dark Matter Universe
Maio, Umberto
2014-01-01
We present results of cosmological N-body hydrodynamic chemistry simulations of primordial structure growth and evolution in a scenario with warm dark matter (WDM) having a mass of 3keV and compare with a model consisting of standard cold dark matter (CDM). We focus on the high-redshift universe ($z>6$), where the structure formation process should better reflect the primordial (linear) differences in terms of matter power spectrum. We find that early epochs are exceptional probes of the dark-matter nature. Non-linear CDM and WDM power spectra differ by up to 2 dex at early times and show spreads of factor of a few persisting in the whole first Gyr. Primordial WDM objects with masses $\\lesssim 10^8\\,\\rm M_\\odot$ are less abundant by $\\gtrsim 1\\,\\rm dex$, both in terms of dark matter and of baryon content. Runaway molecular cooling in primordial WDM mini-haloes results severely inhibited due to the damping of power at large $k$ modes. As a consequence, the cosmic (population III and II-I) star formation activi...
The importance of the cosmic web and halo substructure for power spectra
Pace, Francesco; Bacon, David J; Crittenden, Robert; Percival, Will J
2015-01-01
In this work we study the relevance of the cosmic web and substructures on the matter and lensing power spectra measured from halo mock catalogues extracted from the N-body simulations. Since N-body simulations are computationally expensive, it is common to use faster methods that approximate the dark matter field as a set of halos. In this approximation, we replace mass concentrations in N-body simulations by a spherically symmetric Navarro-Frenk-White halo density profile. We also consider the full mass field as the sum of two distinct fields: dark matter halos ($M>9\\times 10^{12}~M_{\\odot}$/h) and particles not included into halos. Mock halos reproduce well the matter power spectrum, but underestimate the lensing power spectrum on large and small scales. For sources at $z_{\\rm s}=1$ the lensing power spectrum is underestimated by up to 40% at $\\ell\\approx 10^4$ with respect to the simulated halos. The large scale effect can be alleviated by combining the mock catalogue with the dark matter distribution out...
Dark matter annihilation and its effect on CMB and Hydrogen 21 cm observations
Natarajan, Aravind
2009-01-01
If dark matter is made up of Weakly Interacting Massive Particles, the annihilation of these particles in halos results in energy being released, some of which is absorbed by gas, causing partial ionization and heating. It is shown that early ionization results in a transfer of power to higher multipoles in the large angle CMB polarization power spectra. Future CMB experiments may be able to detect this effect in the case of certain light dark matter models. We also investigate the effect of gas heating on the expected H21 cm power spectrum. Heating by particle annihilation results in a decrease in the amplitude of the H21 cm power spectrum as the gas temperature $T$ becomes comparable to the CMB temperature $T_\\gamma$, and then an increase as $T > T_\\gamma$. The result is a minimum in the power spectrum at the redshift for which $T \\approx T_\\gamma$. Only certain models (low particle masses $\\sim$ 10 GeV, or favorable halo parameters) show this effect. Within these models, observations of the H21 cm power sp...
Hints on the nature of dark matter from the properties of Milky Way satellites
Anderhalden, Donnino; Diemand, Juerg [Institute for Theoretical Physics, University of Zürich, Winterthurerstrasse 190, 8057 Zürich (Switzerland); Schneider, Aurel [Department of Physics and Astronomy, University of Sussex, Brighton, BN1 9QH (United Kingdom); Macciň, Andrea V. [Max-Planck-Institute for Astronomy, Königstuhl 17, 69117 Heidelberg (Germany); Bertone, Gianfranco, E-mail: donninoa@physik.uzh.ch, E-mail: aurel.schneider@sussex.ac.uk, E-mail: maccio@mpia.de, E-mail: diemand@physik.uzh.ch, E-mail: gf.bertone@gmail.com [GRAPPA Institute, University of Amsterdam, Science Park 904, 1090 GL Amsterdam (Netherlands)
2013-03-01
The nature of dark matter is still unknown and one of the most fundamental scientific mysteries. Although successfully describing large scales, the standard cold dark matter model (CDM) exhibits possible shortcomings on galactic and sub-galactic scales. It is exactly at these highly non-linear scales where strong astrophysical constraints can be set on the nature of the dark matter particle. While observations of the Lyman-? forest probe the matter power spectrum in the mildly non-linear regime, satellite galaxies of the Milky Way provide an excellent laboratory as a test of the underlying cosmology on much smaller scales. Here we present results from a set of high resolution simulations of a Milky Way sized dark matter halo in eight distinct cosmologies: CDM, warm dark matter (WDM) with a particle mass of 2 keV and six different cold plus warm dark matter (C+WDM) models, varying the fraction, f{sub wdm}, and the mass, m{sub wdm}, of the warm component. We used three different observational tests based on Milky Way satellite observations: the total satellite abundance, their radial distribution and their mass profile. We show that the requirement of simultaneously satisfying all three constraints sets very strong limits on the nature of dark matter. This shows the power of a multi-dimensional small scale approach in ruling out models which would be still allowed by large scale observations.
Dynamic Spectrum Management for Green DSL
this `green DSL' approach, we quantify the power-rate trade-off for different practical settings with some1 Dynamic Spectrum Management for Green DSL Paschalis Tsiaflakisa, , Yung Yib , Mung Chiangc , Marc the total power has become a main target, as IT power consumption has been identified as a significant
Dynamic Spectrum Management for Green DSL
Chiang, Mung
to as `green DSL'. Using this `green DSL' approach, we quantify the power-rate trade-off for different1 Dynamic Spectrum Management for Green DSL Paschalis Tsiaflakisa,, Yung Yib, Mung Chiangc, Marc. However, recently, reducing the total power has become a main target, as IT power consumption has been
Optimal linear reconstruction of dark matter from halo catalogues
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Cai, Yan -Chuan; Bernstein, Gary; Sheth, Ravi K.
2011-04-01
The dark matter lumps (or "halos") that contain galaxies have locations in the Universe that are to some extent random with respect to the overall matter distributions. We investigate how best to estimate the total matter distribution from the locations of the halos. We derive the weight function w(M) to apply to dark-matter haloes that minimizes the stochasticity between the weighted halo distribution and its underlying mass density field. The optimal w(M) depends on the range of masses of halos being used. While the standard biased-Poisson model of the halo distribution predicts that bias weighting is optimal, the simple factmore »that the mass is comprised of haloes implies that the optimal w(M) will be a mixture of mass-weighting and bias-weighting. In N-body simulations, the Poisson estimator is up to 15× noisier than the optimal. Optimal weighting could make cosmological tests based on the matter power spectrum or cross-correlations much more powerful and/or cost effective.« less
Optimal linear reconstruction of dark matter from halo catalogues
Cai, Yan -Chuan; Bernstein, Gary; Sheth, Ravi K.
2011-04-01
The dark matter lumps (or "halos") that contain galaxies have locations in the Universe that are to some extent random with respect to the overall matter distributions. We investigate how best to estimate the total matter distribution from the locations of the halos. We derive the weight function w(M) to apply to dark-matter haloes that minimizes the stochasticity between the weighted halo distribution and its underlying mass density field. The optimal w(M) depends on the range of masses of halos being used. While the standard biased-Poisson model of the halo distribution predicts that bias weighting is optimal, the simple fact that the mass is comprised of haloes implies that the optimal w(M) will be a mixture of mass-weighting and bias-weighting. In N-body simulations, the Poisson estimator is up to 15× noisier than the optimal. Optimal weighting could make cosmological tests based on the matter power spectrum or cross-correlations much more powerful and/or cost effective.
Kevin Crist
2004-10-02
Ohio University, in collaboration with CONSOL Energy, Advanced Technology Systems, Inc (ATS) and Atmospheric and Environmental Research, Inc. (AER) as subcontractors, is evaluating the impact of emissions from coal-fired power plants in the Ohio River Valley region as they relate to the transport and deposition of mercury, arsenic, and associated fine particulate matter. This evaluation will involve two interrelated areas of effort: ambient air monitoring and regional-scale modeling analysis. The scope of work for the ambient air monitoring will include the deployment of a surface air monitoring (SAM) station in southeastern Ohio. The SAM station will contain sampling equipment to collect and measure mercury (including speciated forms of mercury and wet and dry deposited mercury), arsenic, particulate matter (PM) mass, PM composition, and gaseous criteria pollutants (CO, NOx, SO{sub 2}, O{sub 3}, etc.). Laboratory analysis of time-integrated samples will be used to obtain chemical speciation of ambient PM composition and mercury in precipitation. Near-real-time measurements will be used to measure the ambient concentrations of PM mass and all gaseous species including Hg{sup 0} and RGM. Approximately of 18 months of field data will be collected at the SAM site to validate the proposed regional model simulations for episodic and seasonal model runs. The ambient air quality data will also provide mercury, arsenic, and fine particulate matter data that can be used by Ohio Valley industries to assess performance on multi-pollutant control systems. The scope of work for the modeling analysis will include (1) development of updated inventories of mercury and arsenic emissions from coal plants and other important sources in the modeled domain; (2) adapting an existing 3-D atmospheric chemical transport model to incorporate recent advancements in the understanding of mercury transformations in the atmosphere; (3) analyses of the flux of Hg{sup 0}, RGM, arsenic, and fine particulate matter in the different sectors of the study region to identify key transport mechanisms; (4) comparison of cross correlations between species from the model results to observations in order to evaluate characteristics of specific air masses associated with long-range transport from a specified source region; and (5) evaluation of the sensitivity of these correlations to emissions from regions along the transport path. This will be accomplished by multiple model runs with emissions simulations switched on and off from the various source regions. To the greatest extent possible, model results will also be compared to field data collected at other air monitoring sites in the Ohio Valley region, operated independently of this project. These sites may include (1) the DOE National Energy Technologies Laboratory's monitoring site at its suburban Pittsburgh, PA facility; (2) sites in Pittsburgh (Lawrenceville) PA and Holbrook, PA operated by ATS; (3) sites in Steubenville, OH and Pittsburgh, PA operated by U.S. EPA and/or its contractors; and (4) sites operated by State or local air regulatory agencies. Field verification of model results and predictions will provide critical information for the development of cost effective air pollution control strategies by the coal-fired power plants in the Ohio River Valley region.
Kevin Crist
2008-12-31
As stated in the proposal: Ohio University, in collaboration with CONSOL Energy, Advanced Technology Systems, Inc (ATS) and Atmospheric and Environmental Research, Inc. (AER) as subcontractors, evaluated the impact of emissions from coal-fired power plants in the Ohio River Valley region as they relate to the transport and deposition of mercury and associated fine particulate matter. This evaluation involved two interrelated areas of effort: ambient air monitoring and regional-scale modeling analysis. The scope of work for the ambient air monitoring included the deployment of a surface air monitoring (SAM) station in southeastern Ohio. The SAM station contains sampling equipment to collect and measure mercury (including speciated forms of mercury and wet and dry deposited mercury), particulate matter (PM) mass, PM composition, and gaseous criteria pollutants (CO, NOx, SO2, O3, etc.). Laboratory analyses of time-integrated samples were used to obtain chemical speciation of ambient PM composition and mercury in precipitation. Nearreal- time measurements were used to measure the ambient concentrations of PM mass and all gaseous species including Hg0 and RGM. Approximately 30 months of field data were collected at the SAM site to validate the proposed regional model simulations for episodic and seasonal model runs. The ambient air quality data provides mercury, and fine particulate matter data that can be used by Ohio Valley industries to assess performance on multi-pollutant control systems. The scope of work for the modeling analysis includes (1) development of updated inventories of mercury emissions from coal plants and other important sources in the modeled domain; (2) adapting an existing 3-D atmospheric chemical transport model to incorporate recent advancements in the understanding of mercury transformations in the atmosphere; (3) analyses of the flux of Hg0, RGM, and fine particulate matter in the different sectors of the study region to identify key transport mechanisms; (4) comparison of cross correlations between species from the model results to observations in order to evaluate characteristics of specific air masses associated with long-range transport from a specified source region; and (5) evaluation of the sensitivity of these correlations to emissions from regions along the transport path. This is accomplished by multiple model runs with emissions simulations switched on and off from the various source regions. To the greatest extent possible, model results were compared to field data collected at other air monitoring sites in the Ohio Valley region, operated independently of this project. These sites may include (1) the DOE National Energy Technologies Laboratory’s monitoring site at its suburban Pittsburgh, PA facility; (2) sites in Pittsburgh (Lawrenceville) PA and Holbrook, PA operated by ATS; (3) sites in Steubenville, OH and Pittsburgh, PA operated by the USEPA and/or its contractors; and (4) sites operated by State or local air regulatory agencies. Field verification of model results and predictions provides critical information for the development of cost effective air pollution control strategies by the coal-fired power plants in the Ohio River Valley region.
Non-Abelian dark matter and dark radiation
Manuel A. Buen-Abad; Gustavo Marques-Tavares; Martin Schmaltz
2015-07-16
We propose a new class of dark matter models with unusual phenomenology. What is ordinary about our models is that dark matter particles are WIMPs, they are weakly coupled to the Standard Model and have weak scale masses. What is unusual is that they come in multiplets of a new "dark" non-Abelian gauge group with milli-weak coupling. The massless dark gluons of this dark gauge group contribute to the energy density of the universe as a form of weakly self-interacting dark radiation. In this paper we explore the consequences of having i.) dark matter in multiplets ii.) self-interacting dark radiation and iii.) dark matter which is weakly coupled to dark radiation. We find that i.) dark matter cross sections are modified by multiplicity factors which have significant consequences for collider searches and indirect detection, ii.) dark gluons have thermal abundances which affect the CMB as dark radiation. Unlike additional massless neutrino species the dark gluons are interacting and have vanishing viscosity and iii.) the coupling of dark radiation to dark matter represents a new mechanism for damping the large scale structure power spectrum. A combination of additional radiation and slightly damped structure is interesting because it can remove tensions between global $\\Lambda$CDM fits from the CMB and direct measurements of the Hubble expansion rate ($H_0$) and large scale structure ($\\sigma_8$).
Modified Regge Calculus as an Explanation of Dark Matter
Stuckey, W M; Silberstein, Michael
2015-01-01
According to modified Regge calculus (MORC), large-scale rarified distributions of matter can lead to perturbative corrections of the corresponding spacetime geometry of general relativity (GR). It is well known in GR that the dynamic mass of the matter generating the exterior Schwarzschild vacuum solution to Einstein's equations can differ from the proper mass of that same matter per the interior solution. For galactic rotation curves and the mass profiles of X-ray clusters, we use MORC to propose that it is precisely this type of mass difference on an enhanced scale that is currently attributed to non-baryonic dark matter. We argue that this same approach is applicable to Regge calculus cosmology and the modeling of anisotropies in the angular power spectrum of the CMB due to acoustic oscillations, so it should be applicable to explaining dark matter phenomena on that scale as well. We account for the value of the dynamic mass by a simple geometric scaling of the proper mass of the baryonic matter in galaxi...
Baryonic matter perturbations in decaying vacuum cosmology
Marttens, R.F. vom; Zimdahl, W.; Hipólito-Ricaldi, W.S. E-mail: wiliam.ricaldi@ufes.br
2014-08-01
We consider the perturbation dynamics for the cosmic baryon fluid and determine the corresponding power spectrum for a ?(t)CDM model in which a cosmological term decays into dark matter linearly with the Hubble rate. The model is tested by a joint analysis of data from supernovae of type Ia (SNIa) (Constitution and Union 2.1), baryonic acoustic oscillations (BAO), the position of the first peak of the anisotropy spectrum of the cosmic microwave background (CMB) and large-scale-structure (LSS) data (SDSS DR7). While the homogeneous and isotropic background dynamics is only marginally influenced by the baryons, there are modifications on the perturbative level if a separately conserved baryon fluid is included. Considering the present baryon fraction as a free parameter, we reproduce the observed abundance of the order of 5% independently of the dark-matter abundance which is of the order of 32% for this model. Generally, the concordance between background and perturbation dynamics is improved if baryons are explicitly taken into account.
Dark-matter harmonics beyond annual modulation
Lee, Samuel K.; Lisanti, Mariangela; Safdi, Benjamin R. E-mail: mlisanti@princeton.edu
2013-11-01
The count rate at dark-matter direct-detection experiments should modulate annually due to the motion of the Earth around the Sun. We show that higher-frequency modulations, including daily modulation, are also present and in some cases are nearly as strong as the annual modulation. These higher-order modes are particularly relevant if (i) the dark matter is light, O(10) GeV, (ii) the scattering is inelastic, or (iii) velocity substructure is present; for these cases, the higher-frequency modes are potentially observable at current and ton-scale detectors. We derive simple expressions for the harmonic modes as functions of the astrophysical and geophysical parameters describing the Earth's orbit, using an updated expression for the Earth's velocity that corrects a common error in the literature. For an isotropic halo velocity distribution, certain ratios of the modes are approximately constant as a function of nuclear recoil energy. Anisotropic distributions can also leave observable features in the harmonic spectrum. Consequently, the higher-order harmonic modes are a powerful tool for identifying a potential signal from interactions with the Galactic dark-matter halo.
Radiation, Matter and Energy What is light?
Shirley, Yancy
Radiation, Matter and Energy #12;What is light? #12;Light is an electromagnetic wave #12;Light is an electromagnetic wave #12;#12;Light is also a particle Photons: "pieces" of light, each with precise wavelength the visible spectrum, blue light has higher energy than red light Within the electromagnetic spectrum, X
Quinn E. Minor; Manoj Kaplinghat
2015-03-08
We point out three correlated predictions of the axion monodromy inflation model: large amplitude of gravitational waves, suppression of power on horizon scales and on scales relevant for the formation of dwarf galaxies. While these predictions are likely generic to models with oscillations in the inflaton potential, the axion monodromy model naturally accommodates the required running spectral index through Planck-scale corrections to the inflaton potential. Applying this model to a combined data set of Planck, ACT, SPT, and WMAP low-$\\ell$ polarization cosmic microwave background (CMB) data, we find a best-fit tensor-to-scalar ratio $r_{0.05} = 0.07^{+0.05}_{-0.04}$ due to gravitational waves, which may have been observed by the BICEP2 experiment. Despite the contribution of gravitational waves, the total power on large scales (CMB power spectrum at low multipoles) is lower than the standard $\\Lambda$CDM cosmology with a power-law spectrum of initial perturbations and no gravitational waves, thus mitigating some of the tension on large scales. There is also a reduction in the matter power spectrum of 20-30\\% at scales corresponding to $k = 10~{\\rm Mpc}^{-1}$, which are relevant for dwarf galaxy formation. This will alleviate some of the unsolved small-scale structure problems in the standard $\\Lambda$CDM cosmology. The inferred matter power spectrum is also found to be consistent with recent Lyman-$\\alpha$ forest data, which is in tension with the Planck-favored $\\Lambda$CDM model with power-law primordial power spectrum.
Dark matter annihilation or unresolved astrophysical sources...
Office of Scientific and Technical Information (OSTI)
should be a powerful tool for revealing the CGB origin, and potentially for the first detection of dark matter annihilation. Authors: Ando, Shin'ichiro ; Komatsu, Eiichiro ;...
Power Spectrum Analyses of Nuclear Decay Rates
Javorsek, D; Lasenby, R N; Lasenby, A N; Buncher, J B; Fischbach, E; Gruenwald, J T; Hoft, A W; Horan, T J; Jenkins, J H; Kerford, J L; Lee, R H; Longman, A; Mattes, J J; Morreale, B L; Morris, D B; Mudry, R N; Newport, J R; O'Keefe, D; Petrelli, M A; Silver, M A; Stewart, C A; Terry, B; 10.1016/j.astropartphys.2010.06.011
2010-01-01
We provide the results from a spectral analysis of nuclear decay data displaying annually varying periodic fluctuations. The analyzed data were obtained from three distinct data sets: 32Si and 36Cl decays reported by an experiment performed at the Brookhaven National Laboratory (BNL), 56Mn decay reported by the Children's Nutrition Research Center (CNRC), but also performed at BNL, and 226Ra decay reported by an experiment performed at the Physikalisch-Technische Bundesanstalt (PTB) in Germany. All three data sets exhibit the same primary frequency mode consisting of an annual period. Additional spectral comparisons of the data to local ambient temperature, atmospheric pressure, relative humidity, Earth-Sun distance, and their reciprocals were performed. No common phases were found between the factors investigated and those exhibited by the nuclear decay data. This suggests that either a combination of factors was responsible, or that, if it was a single factor, its effects on the decay rate experiments are n...
Power Spectrum Analyses of Nuclear Decay Rates
D. Javorsek II; P. A. Sturrock; R. N. Lasenby; A. N. Lasenby; J. B. Buncher; E. Fischbach; J. T. Gruenwald; A. W. Hoft; T. J. Horan; J. H. Jenkins; J. L. Kerford; R. H. Lee; A. Longman; J. J. Mattes; B. L. Morreale; D. B. Morris; R. N. Mudry; J. R. Newport; D. O'Keefe; M. A. Petrelli; M. A. Silver; C. A. Stewart; B. Terry
2010-07-06
We provide the results from a spectral analysis of nuclear decay data displaying annually varying periodic fluctuations. The analyzed data were obtained from three distinct data sets: 32Si and 36Cl decays reported by an experiment performed at the Brookhaven National Laboratory (BNL), 56Mn decay reported by the Children's Nutrition Research Center (CNRC), but also performed at BNL, and 226Ra decay reported by an experiment performed at the Physikalisch-Technische Bundesanstalt (PTB) in Germany. All three data sets exhibit the same primary frequency mode consisting of an annual period. Additional spectral comparisons of the data to local ambient temperature, atmospheric pressure, relative humidity, Earth-Sun distance, and their reciprocals were performed. No common phases were found between the factors investigated and those exhibited by the nuclear decay data. This suggests that either a combination of factors was responsible, or that, if it was a single factor, its effects on the decay rate experiments are not a direct synchronous modulation. We conclude that the annual periodicity in these data sets is a real effect, but that further study involving additional carefully controlled experiments will be needed to establish its origin.
Blue running of the primordial tensor spectrum
Gong, Jinn-Ouk
2014-07-01
We examine the possibility of positive spectral index of the power spectrum of the primordial tensor perturbation produced during inflation in the light of the detection of the B-mode polarization by the BICEP2 collaboration. We find a blue tilt is in general possible when the slow-roll parameter decays rapidly. We present two known examples in which a positive spectral index for the tensor power spectrum can be obtained. We also briefly discuss other consistency tests for further studies on inflationary dynamics.
Blue running of the primordial tensor spectrum
Jinn-Ouk Gong
2014-07-09
We examine the possibility of positive spectral index of the power spectrum of the primordial tensor perturbation produced during inflation in the light of the detection of the B-mode polarization by the BICEP2 collaboration. We find a blue tilt is in general possible when the slow-roll parameter decays rapidly. We present two known examples in which a positive spectral index for the tensor power spectrum can be obtained. We also briefly discuss other consistency tests for further studies on inflationary dynamics.
Radiation detector spectrum simulator
Wolf, Michael A. (Los Alamos, NM); Crowell, John M. (Los Alamos, NM)
1987-01-01
A small battery operated nuclear spectrum simulator having a noise source nerates pulses with a Gaussian distribution of amplitudes. A switched dc bias circuit cooperating therewith generates several nominal amplitudes of such pulses and a spectral distribution of pulses that closely simulates the spectrum produced by a radiation source such as Americium 241.
Radiation detector spectrum simulator
Wolf, M.A.; Crowell, J.M.
1985-04-09
A small battery operated nuclear spectrum simulator having a noise source generates pulses with a Gaussian distribution of amplitudes. A switched dc bias circuit cooperating therewith to generate several nominal amplitudes of such pulses and a spectral distribution of pulses that closely simulates the spectrum produced by a radiation source such as Americium 241.
Joseph Silk
2010-01-08
One of the greatest mysteries in the cosmos is that it is mostly dark. Astronomers and particle physicists today are seeking to unravel the nature of this mysterious, but pervasive dark matter which has profoundly influenced the formation of structure in the universe. I will describe the complex interplay between galaxy formation and dark matter detectability and review recent attempts to measure particle dark matter by direct and indirect means.
Axion hot dark matter bounds after Planck
Archidiacono, Maria; Hannestad, Steen; Mirizzi, Alessandro; Raffelt, Georg; Wong, Yvonne Y.Y. E-mail: sth@phys.au.dk E-mail: raffelt@mpp.mpg.de
2013-10-01
We use cosmological observations in the post-Planck era to derive limits on thermally produced cosmological axions. In the early universe such axions contribute to the radiation density and later to the hot dark matter fraction. We find an upper limit m{sub a} < 0.67 eV at 95% C.L. after marginalising over the unknown neutrino masses, using CMB temperature and polarisation data from Planck and WMAP respectively, the halo matter power spectrum extracted from SDSS-DR7, and the local Hubble expansion rate H{sub 0} released by the Carnegie Hubble Program based on a recalibration of the Hubble Space Telescope Key Project sample. Leaving out the local H{sub 0} measurement relaxes the limit somewhat to 0.86 eV, while Planck+WMAP alone constrain the axion mass to 1.01 eV, the first time an upper limit on m{sub a} has been obtained from CMB data alone. Our axion limit is therefore not very sensitive to the tension between the Planck-inferred H{sub 0} and the locally measured value. This is in contrast with the upper limit on the neutrino mass sum, which we find here to range from ? m{sub ?} < 0.27 eV at 95% C.L. combining all of the aforementioned observations, to 0.84 eV from CMB data alone.
Broader source: Energy.gov [DOE]
QM Power’s Q-Sync™ is an innovative, highly efficient and cost effective motor technology. Utilizing DoE SBIR funding, QM Power has developed advanced Q-Sync fan motor technology for 9-12 watt commercial refrigeration fan applications and is launching its first product lines targeting both new and existing commercial refrigeration equipment. For this project, QM Power will team with Oak Ridge National Labs, market leading OEMs, subject matter experts, end users, retrofit contractors and utilities to install and demonstrate approximately 10,000 high efficiency Q-Sync fan motors in over 50 grocery sites throughout the US.
Exploring a new interaction between dark matter and dark energy using the growth rate of structure
Martín G. Richarte; Lixin Xu
2015-06-08
We present a phenomenological interaction with a scale factor power law form which leads to the appearance of two kinds of perturbed terms, a scale factor spatial variation along with perturbed Hubble expansion rate. We study both the background and the perturbation evolution within the parametrized post-Friedmann scheme, obtaining that the exchange of energy-momentum can flow from dark energy to dark matter in order to keep dark energy and dark matter densities well defined at all times. We combine several measures of the cosmic microwave background (WMAP9+Planck) data, baryon acoustic oscillation measurements, redshift-space distortion data, JLA sample of supernovae, and Hubble constant for constraining the coupling constant and the exponent provided both parametrized the interaction itself. The joint analysis of ${\\rm Planck+WMAP9+BAO}$ ${\\rm +RSD+JLA+HST}$ data seems to favor large coupling constant, $\\xi_c = 0.34403427_{- 0.18907353}^{+ 0.14430125}$ at 1 $\\sigma$ level, and prefers a power law interaction with a negative exponent, thus $\\beta= -0.50863232_{- 0.40923857}^{+ 0.48424166}$ at 1 $\\sigma$ level. The CMB temperature power spectrum indicates that a large coupling constant produces a shift of the acoustic peaks and affects their amplitudes at lower multipoles. In addition, a larger $\\beta$ exponent generates a shift of the acoustic peaks, pointing a clear deviation with respect to the concordance model. The matter power spectrum are sensitive to the variation of the coupling constant and the $\\beta$ exponent. In this context, the interaction alters the scale of matter and radiation equality and pushes it away from the present era, which in turn generates a shift of the turnover point toward to smaller scale.
Gupalo, D.; Kaganovich, A.S.; Cohen, E.G.D. (Rockefeller Univ., New York, NY (United States))
1994-03-01
The symmetry of the spectrum of Lyapunov exponents provides a useful quantitative connection between properties of dynamical systems consisting of N interacting particles coupled to a thermostat, and nonequilibrium statistical mechanics. The authors obtain here sufficient conditions for this symmetry and analyze the structure of 1/N corrections ignored in previous studies. The relation of the Lyapunov spectrum symmetry with some other symmetries of dynamical systems is discussed.
Revenue Management for Cognitive Spectrum Underlay Networks: An Interference Elasticity
Huang, Jianwei
to the large body of work on uplink power control with pricing for CDMA networks (e.g., [5][10] and a recent a total received interference power constraint at the primary user's receiver. The transmission power1 Revenue Management for Cognitive Spectrum Underlay Networks: An Interference Elasticity
Low Overhead Dynamic Spectrum Reallocation in Opportunistic Spectrum Access Networks
Fu, Xiaoming
-August-University of Goettingen, Germany Email: {tianyu, lwz}@dislab.nju.edu.cn, fu@cs.uni-goettingen.de Abstract-- Opportunistic by sharing spec- trum usage. To make full use of the spectrum holes [2] and achieve a global optimal goal) it consumes extra energy to accomplish the process of spectrum sensing, spectrum choosing, and spectrum
Detecting electron neutrinos from solar dark matter annihilation by JUNO
Guo, Wan-Lei
2015-01-01
We explore the electron neutrino signals from light dark matter (DM) annihilation in the Sun for the large liquid scintillator detector JUNO. In terms of the spectrum features of three typical DM annihilation channels $\\chi \\chi \\rightarrow \
Walukiewicz, Wladyslaw (Kensington, CA); Yu, Kin Man (Lafayette, CA); Wu, Junqiao (Richmond, CA); Schaff, William J. (Ithaca, NY)
2007-05-15
An alloy having a large band gap range is used in a multijunction solar cell to enhance utilization of the solar energy spectrum. In one embodiment, the alloy is In.sub.1-xGa.sub.xN having an energy bandgap range of approximately 0.7 eV to 3.4 eV, providing a good match to the solar energy spectrum. Multiple junctions having different bandgaps are stacked to form a solar cell. Each junction may have different bandgaps (realized by varying the alloy composition), and therefore be responsive to different parts of the spectrum. The junctions are stacked in such a manner that some bands of light pass through upper junctions to lower junctions that are responsive to such bands.
None
2013-05-29
There are many voices calling for a future of abundant clean energy. The choices are difficult and the challenges daunting. How will we get there? The National Renewable Energy Laboratory integrates the entire spectrum of innovation including fundamental science, market relevant research, systems integration, testing and validation, commercialization and deployment. The innovation process at NREL is interdependent and iterative. Many scientific breakthroughs begin in our own laboratories, but new ideas and technologies come to NREL at any point along the innovation spectrum to be validated and refined for commercial use.
Dark Matter from Late Invisible Decays to/of Gravitinos
Rouzbeh Allahverdi; Bhaskar Dutta; Farinaldo S. Queiroz; Louis E. Strigari; Mei-Yu Wang
2014-12-27
In this work, we sift a simple supersymmetric framework of late invisible decays to/of the gravitino. We investigate two cases where the gravitino is the lightest supersymmetric particle or the next-to-lightest supersymmetric particle. The next-to-lightest supersymmetric particle decays into two dark matter candidates and has a long lifetime due to gravitationally suppressed interactions. However, because of the absence of any hadronic or electromagnetic products, it satisfies the tight bounds set by big bang nucleosynthesis and cosmic microwaved background. One or both of the dark matter candidates produced in invisible decays can contribute to the amount of dark radiation and suppress perturbations at scales that are being probed by the galaxy power spectrum and the Lyman-alpha forest data. We show that these constraints are satisfied in large regions of the parameter space and, as a result, the late invisible decays to/of the gravitino can be responsible for the entire dark matter relic abundance.
The matter bounce scenario in loop quantum cosmology
Wilson-Ewing, Edward, E-mail: wilson-ewing@cpt.univ-mrs.fr [Aix-Marseille Université, CNRS UMR 7332, CPT, 13288 Marseille (France)
2013-03-01
In the matter bounce scenario, a dust-dominated contracting space-time generates scale-invariant perturbations that, assuming a nonsingular bouncing cosmology, propagate to the expanding branch and set appropriate initial conditions for the radiation-dominated era. Since this scenario depends on the presence of a bounce, it seems appropriate to consider it in the context of loop quantum cosmology where a bouncing universe naturally arises. For a pressureless collapsing universe in loop quantum cosmology, the predicted power spectrum of the scalar perturbations after the bounce is scale-invariant and the tensor to scalar ratio is negligibly small. A slight red tilt can be given to the scale-invariance of the scalar perturbations by a scalar field whose equation of state is P = ???, where ? is a small positive number. Then, the power spectrum for tensor perturbations is also almost scale-invariant with the same red tilt as the scalar perturbations, and the tensor to scalar ratio is expected to be r ? 9 × 10{sup ?4}. Finally, for the predicted amplitude of the scalar perturbations to agree with observations, the critical density in loop quantum cosmology must be of the order ?{sub c} ? 10{sup ?9}?{sub Pl}.
2012-2013 Keywords: Routing and spectrum allocation (RSA), flexible optical networks
Varvarigo, Emmanouel "Manos"
, "Conserving Transmission Power in Wireless Ad Hoc Networks" #12;), flexible optical networks WDM (FWDM) . (RSA) (RWA). FWDM Matlab. 2: Keywords: Routing and spectrum allocation (RSA), flexible optical networks
Scaling Relations for Collision-less Dark Matter Turbulence
Akika Nakamichi; Masahiro Morikawa
2009-06-15
Many scaling relations are observed for self-gravitating systems in the universe. We explore the consistent understanding of them from a simple principle based on the proposal that the collision-less dark matter fluid terns into a turbulent state, i.e. dark turbulence, after crossing the caustic surface in the non-linear stage. The dark turbulence will not eddy dominant reflecting the collision-less property. After deriving Kolmogorov scaling laws from Navier-Stokes equation by the method similar to the one for Smoluchowski coagulation equation, we apply this to several observations such as the scale-dependent velocity dispersion, mass-luminosity ratio, magnetic fields, and mass-angular momentum relation, power spectrum of density fluctuations. They all point the concordant value for the constant energy flow per mass: $0.3 cm^2/sec^3$, which may be understood as the speed of the hierarchical coalescence process in the cosmic structure formation.
Particle dark matter searches outside the Local neighborhood
Regis, Marco; Cuoco, Alessandro; Branchini, Enzo; Fornengo, Nicolao; Viel, Matteo
2015-01-01
If dark matter (DM) is composed by particles which are non-gravitationally coupled to ordinary matter, their annihilations or decays in cosmic structures can result in detectable radiation. We show that the most powerful technique to detect a particle DM signal outside the Local Group is to study the angular cross-correlation of non-gravitational signals with low-redshift gravitational probes. This method allows to enhance signal-to-noise from the regions of the Universe where the DM-induced emission is preferentially generated. We demonstrate the power of this approach by focusing on GeV-TeV DM and on the recent cross-correlation analysis between the 2MASS galaxy catalogue and the Fermi-LAT gamma-ray maps. We show that this technique is more sensitive than other extragalactic gamma-ray probes, such as the energy spectrum and angular autocorrelation of the extragalactic background, and emission from clusters of galaxies. Intriguingly, we find that the measured cross-correlation can be well fitted by a DM comp...
Flavored dark matter beyond minimal flavor violation
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Agrawal, Prateek; Blanke, Monika; Gemmler, Katrin
2014-10-13
We study the interplay of flavor and dark matter phenomenology for models of flavored dark matter interacting with quarks. We allow an arbitrary flavor structure in the coupling of dark matter with quarks. This coupling is assumed to be the only new source of violation of the Standard Model flavor symmetry extended by a U(3)x associated with the dark matter. We call this ansatz Dark Minimal Flavor Violation (DMFV) and highlight its various implications, including an unbroken discrete symmetry that can stabilize the dark matter. As an illustration we study a Dirac fermionic dark matter ? which transforms asmore »triplet under U(3)x , and is a singlet under the Standard Model. The dark matter couples to right-handed down-type quarks via a colored scalar mediator ? with a coupling ?. We identify a number of “flavor-safe” scenarios for the structure of ? which are beyond Minimal Flavor Violation. For dark matter and collider phenomenology we focus on the well-motivated case of b-flavored dark matter. The combined flavor and dark matter constraints on the parameter space of ? turn out to be interesting intersections of the individual ones. LHC constraints on simplified models of squarks and sbottoms can be adapted to our case, and monojet searches can be relevant if the spectrum is compressed.« less
Dark Matter Hawking Radiation? Dark Spinors Tunnelling in String Theory Black Holes
Cavalcanti, R T
2015-01-01
The Hawking radiation spectrum of Kerr-Sen axion-dilaton black holes is derived, in the context of dark spinors tunnelling across the horizon. Since a black hole has a well defined temperature, it should radiate in principle all the standard model particles, similar to a black body at that temperature. We investigate the tunnelling of mass dimension one spin-1/2 dark fermions, that are beyond the standard model and are prime candidates to the dark matter. Their interactions with the standard model matter and gauge fields are suppressed by at least one power of unification scale, being restricted just to the Higgs field and to the graviton likewise. The tunnelling method for the emission and absorption of mass dimension one particles across the event horizon of Kerr-Sen axion-dilaton black holes is shown here to provide further evidence for the universality of black hole radiation, further encompassing particles beyond the standard model.
Dark Matter Hawking Radiation? Dark Spinors Tunnelling in String Theory Black Holes
R. T. Cavalcanti; Roldao da Rocha
2015-07-14
The Hawking radiation spectrum of Kerr-Sen axion-dilaton black holes is derived, in the context of dark spinors tunnelling across the horizon. Since a black hole has a well defined temperature, it should radiate in principle all the standard model particles, similar to a black body at that temperature. We investigate the tunnelling of mass dimension one spin-1/2 dark fermions, that are beyond the standard model and are prime candidates to the dark matter. Their interactions with the standard model matter and gauge fields are suppressed by at least one power of unification scale, being restricted just to the Higgs field and to the graviton likewise. The tunnelling method for the emission and absorption of mass dimension one particles across the event horizon of Kerr-Sen axion-dilaton black holes is shown here to provide further evidence for the universality of black hole radiation, further encompassing particles beyond the standard model.
Two Emission Mechanisms in the Fermi Bubbles: A Possible Signal of Annihilating Dark Matter
Hooper, Dan; Slatyer, Tracy R.
2013-09-01
We study the variation of the spectrum of the Fermi Bubbles with Galactic latitude. Far from the Galactic plane (|b| > 30 degrees), the observed gamma-ray emission is nearly invariant with latitude, and is consistent with arising from inverse Compton scattering of the interstellar radiation field by cosmic-ray electrons with an approximately power-law spectrum. The same electrons in the presence of microgauss-scale magnetic fields can also generate the the observed microwave "haze". At lower latitudes (b < 20 degrees), in contrast, the spectrum of the emission correlated with the Bubbles possesses a pronounced spectral feature peaking at 1-4 GeV (in E^2 dN/dE) which cannot be generated by any realistic spectrum of electrons. Instead, we conclude that a second (non-inverse-Compton) emission mechanism must be responsible for the bulk of the low-energy, low-latitude emission. This second component is spectrally similar to the excess GeV emission previously reported from the Galactic Center (GC), and also appears spatially consistent with a luminosity per volume falling approximately as r^-2.4, where r is the distance from the GC. We argue that the spectral feature visible in the low-latitude Bubbles is the extended counterpart of the GC excess, now detected out to at least 2-3 kpc from the GC. The spectrum and angular distribution of the signal is consistent with that predicted from ~10 GeV dark matter particles annihilating to leptons, or from ~50 GeV dark matter particles annihilating to quarks, following a distribution similar to the canonical Navarro-Frenk-White (NFW) profile. We also consider millisecond pulsars as a possible astrophysical explanation for the signal, as observed millisecond pulsars possess a spectral cutoff at approximately the required energy. Any such scenario would require a large population of unresolved millisecond pulsars extending at least 2-3 kpc from the GC.
Anticipating Patentable Subject Matter
Burk, DL
2015-01-01
February 2013] PATENTABLE SUBJECT MATTER patentability—imports into patent law’s subject matter provisions theunder either novelty or subject matter. The proper question
Matter Field, Dark Matter and Dark Energy
Masayasu Tsuge
2009-03-24
A model concerning particle theory and cosmology is proposed. Matter field, dark matter and dark energy are created by an energy flow from space to primordial matter fields at the phase transition in the early universe.
Hybrid spread spectrum radio system
Smith, Stephen F. (London, TN) [London, TN; Dress, William B. (Camas, WA) [Camas, WA
2010-02-09
Systems and methods are described for hybrid spread spectrum radio systems. A method, includes receiving a hybrid spread spectrum signal including: fast frequency hopping demodulating and direct sequence demodulating a direct sequence spread spectrum signal, wherein multiple frequency hops occur within a single data-bit time and each bit is represented by chip transmissions at multiple frequencies.
Spectrum Sensing and Reconstruction for Cognitive Radio
Qiu, Robert Caiming
to explore and exploit the free spectrum. Spectrum analyzer is used to emulate cognitive radio to do spectrum should keep silent; otherwise, cognitive radio can access this spectrum. In this paper, spectrum analyzer- rithm of sensing spectrum and transmission schemes [6]. Pre- viously, spectrum analyzer was controlled
NuSTAR observations of the powerful radio-galaxy Cygnus A
Reynolds, Christopher S; Ogle, Patrick M; Harrison, Fiona A; Madsen, Kristin K; Fabian, Andrew C; Wik, Daniel R; Madejski, Grzegorz; Ballantyne, David R; Boggs, Steven E; Christensen, Finn E; Craig, William W; Fuerst, Felix; Hailey, Charles J; Lanz, Lauranne; Miller, Jon M; Saez, Cristian; Stern, Daniel; Walton, Dominic J; Zhang, William
2015-01-01
We present NuSTAR observations of the powerful radio galaxy Cygnus A, focusing on the central absorbed active galactic nucleus (AGN). Cygnus A is embedded in a cool-core galaxy cluster, and hence we also examine archival XMM-Newton data to facilitate the decomposition of the spectrum into the AGN and intracluster medium (ICM) components. NuSTAR gives a source-dominated spectrum of the AGN out to >70keV. In gross terms, the NuSTAR spectrum of the AGN has the form of a power law (Gamma~1.6-1.7) absorbed by a neutral column density of N_H~1.6x10^23 cm^-2. However, we also detect curvature in the hard (>10keV) spectrum resulting from reflection by Compton-thick matter out of our line-of-sight to the X-ray source. Compton reflection, possibly from the outer accretion disk or obscuring torus, is required even permitting a high-energy cutoff in the continuum source; the limit on the cutoff energy is E_cut>111keV (90% confidence). Interestingly, the absorbed power-law plus reflection model leaves residuals suggesting...
Davis, Jonathan H
2015-01-01
Future multi-tonne Direct Detection experiments will be sensitive to solar neutrino induced nuclear recoils which form an irreducible background to light Dark Matter searches. Indeed for masses around 6 GeV the spectra of neutrinos and Dark Matter are so similar that experiments will run into a neutrino floor, for which sensitivity increases only marginally with exposure past a certain cross section. In this work we show that this floor can be overcome using the different annual modulation expected from solar neutrinos and Dark Matter. Specifically for cross sections below the neutrino floor the DM signal is observable through a phase shift and a smaller amplitude for the time-dependent event rate. This allows the exclusion power to be improved by up to an order of magnitude for large exposures. In addition we demonstrate that the neutrino floor exists over a wider mass range than has been previously shown, since the large uncertainties in the Dark Matter velocity distribution make the signal spectrum harder ...
Jonathan H. Davis
2015-03-09
Future multi-tonne Direct Detection experiments will be sensitive to solar neutrino induced nuclear recoils which form an irreducible background to light Dark Matter searches. Indeed for masses around 6 GeV the spectra of neutrinos and Dark Matter are so similar that experiments will run into a neutrino floor, for which sensitivity increases only marginally with exposure past a certain cross section. In this work we show that this floor can be overcome using the different annual modulation expected from solar neutrinos and Dark Matter. Specifically for cross sections below the neutrino floor the DM signal is observable through a phase shift and a smaller amplitude for the time-dependent event rate. This allows the exclusion power to be improved by up to an order of magnitude for large exposures. In addition we demonstrate that the neutrino floor exists over a wider mass range than has been previously shown, since the large uncertainties in the Dark Matter velocity distribution make the signal spectrum harder to distinguish from the neutrino background. However for most velocity distributions the neutrino floor can still be surpassed using timing information, though certain velocity streams may prove problematic.
Redshifting Rings of Power U. Michigan, May 2003
Hu, Wayne
Spectrum #12;Radiation and Dark Matter · Radiation domination: potential wells created by CMB itself · Pressure support potential decay driving · Heights measures when dark matter dominates #12;Dark Matter of the photons in the baryons C = -1 where = neT a is the conformal opacity to Thompson scattering · Dissipation
Shocking Signals of Dark Matter Annihilation
Davis, Jonathan H; Boehm, Celine; Kotera, Kumiko; Norman, Colin
2015-01-01
We examine whether charged particles injected by self-annihilating Dark Matter into regions undergoing Diffuse Shock Acceleration (DSA) can be accelerated to high energies. We consider three astrophysical sites where shock acceleration is supposed to occur, namely the Galactic Centre, galaxy clusters and Active Galactic Nuclei (AGN). For the Milky Way, we find that the acceleration of cosmic rays injected by dark matter could lead to a bump in the cosmic ray spectrum provided that the product of the efficiency of the acceleration mechanism and the concentration of DM particles is high enough. Among the various acceleration sources that we consider (namely supernova remnants (SNRs), Fermi bubbles and AGN jets), we find that the Fermi bubbles are a potentially more efficient accelerator than SNRs. However both could in principle accelerate electrons and protons injected by dark matter to very high energies. At the extragalactic level, the acceleration of dark matter annihilation products could be responsible fo...
Matter Wave Radiation Leading to Matter Teleportation
Yong-Yi Huang
2015-02-12
The concept of matter wave radiation is put forward, and its equation is established for the first time. The formalism solution shows that the probability density is a function of displacement and time. A free particle and a two-level system are reinvestigated considering the effect of matter wave radiation. Three feasible experimental designs, especially a modified Stern-Gerlach setup, are proposed to verify the existence of matter wave radiation. Matter wave radiation effect in relativity has been formulated in only a raw formulae, which offers another explanation of Lamb shift. A possible mechanics of matter teleportation is predicted due to the effect of matter wave radiation.
Kenji Fukushima
2014-10-01
We summarize recent developments in identifying the ground state of dense baryonic matter and beyond. The topics include deconfinement from baryonic matter to quark matter, a diquark mixture, topological effect coupled with chirality and density, and inhomogeneous chiral condensates.
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Wind Power Bioenergy Power Systems Wind Power Wind Power Main Page Outreach Programs Image Gallery FAQs Links Software Hydro Power INL Home Wind Power Introduction The Wind Power...
PINS Spectrum Identification Guide
A.J. Caffrey
2012-03-01
The Portable Isotopic Neutron Spectroscopy—PINS, for short—system identifies the chemicals inside munitions and containers without opening them, a decided safety advantage if the fill chemical is a hazardous substance like a chemical warfare agent or an explosive. The PINS Spectrum Identification Guide is intended as a reference for technical professionals responsible for the interpretation of PINS gamma-ray spectra. The guide is divided into two parts. The three chapters that constitute Part I cover the science and technology of PINS. Neutron activation analysis is the focus of Chapter 1. Chapter 2 explores PINS hardware, software, and related operational issues. Gamma-ray spectral analysis basics are introduced in Chapter 3. The six chapters of Part II cover the identification of PINS spectra in detail. Like the PINS decision tree logic, these chapters are organized by chemical element: phosphorus-based chemicals, chlorine-based chemicals, etc. These descriptions of hazardous, toxic, and/or explosive chemicals conclude with a chapter on the identification of the inert chemicals, e.g. sand, used to fill practice munitions.
Universal Spectrum for Atmospheric Suspended Particulates: Comparison with Observations
A. M. Selvam
2011-08-25
Atmospheric flows exhibit self-similar fractal space-time fluctuations on all space-time scales in association with inverse power law distribution for power spectra of meteorological parameters such as wind, temperature, etc., and thus implies long-range correlations, identified as self-organized criticality generic to dynamical systems in nature. A general systems theory based on classical statistical physical concepts developed by the author visualizes the fractal fluctuations to result from the coexistence of eddy fluctuations in an eddy continuum, the larger scale eddies being the integrated mean of enclosed smaller scale eddies. The model satisfies the maximum entropy principle and predicts that the probability distributions of component eddy amplitudes and the corresponding variances (power spectra) are quantified by the same universal inverse power law distribution which is a function of the golden mean. Atmospheric particulates are held in suspension by the vertical velocity distribution (spectrum). The atmospheric particulate size spectrum is derived in terms of the model predicted universal inverse power law characterizing atmospheric eddy spectrum. Model predicted spectrum is in agreement with the following four experimentally determined data sets: (i) CIRPAS mission TARFOX_WALLOPS_SMPS aerosol size distributions (ii) CIRPAS mission ARM-IOP (Ponca City, OK) aerosol size distributions (iii) SAFARI 2000 CV-580 (CARG Aerosol and Cloud Data) cloud drop size distributions and (iv) TWP-ICE (Darwin, Australia) rain drop size distributions.
Thomas D. Cohen
2010-03-15
It is shown that large Nc QCD must have a Hagedorn spectrum (i.e. a spectrum of hadron which grows exponentially with the hadrons mass) provided that certain technical assumptions concerning the applicability of perturbation theory to a certain class of correlation functions apply. The basic argument exploits the interplay of confinement and asymptotic freedom.
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power AdministrationRobust,Field-effectWorkingLosThe 26th AnnualHistoryMIII:National LaboratoryEffectMicro-XCTnu0001
Dark matter from decaying topological defects
Hindmarsh, Mark [Helsinki Institute of Physics, Gustaf Hällströmin katu, P.O. Box 64, 00014 Helsinki University (Finland); Kirk, Russell; West, Stephen M., E-mail: m.b.hindmarsh@sussex.ac.uk, E-mail: russell.kirk.2008@live.rhul.ac.uk, E-mail: stephen.west@rhul.ac.uk [Dept. of Physics, Royal Holloway University of London, Egham Hill, Egham, Surrey, TW20 0EX (United Kingdom)
2014-03-01
We study dark matter production by decaying topological defects, in particular cosmic strings. In topological defect or ''top-down'' (TD) scenarios, the dark matter injection rate varies as a power law with time with exponent p?4. We find a formula in closed form for the yield for all p < 3/2, which accurately reproduces the solution of the Boltzmann equation. We investigate two scenarios (p = 1, p = 7/6) motivated by cosmic strings which decay into TeV-scale states with a high branching fraction into dark matter particles. For dark matter models annihilating either by s-wave or p-wave, we find the regions of parameter space where the TD model can account for the dark matter relic density as measured by Planck. We find that topological defects can be the principal source of dark matter, even when the standard freeze-out calculation under-predicts the relic density and hence can lead to potentially large ''boost factor'' enhancements in the dark matter annihilation rate. We examine dark matter model-independent limits on this scenario arising from unitarity and discuss example model-dependent limits coming from indirect dark matter search experiments. In the four cases studied, the upper bound on G? for strings with an appreciable channel into TeV-scale states is significantly more stringent than the current Cosmic Microwave Background limits.
Stillwater Power Plant Wabuska Power Plant Casa Diablo Power Plant Glass Mountain Geothermal Area Lassen Geothermal Area Coso Hot Springs Power Plants Lake City Geothermal Area Thermo Geothermal Area Lakeview Geothermal Area Raft River Geothermal Area Cove Fort Power Plant Roosevelt Power Plant Borax Lake
The Optical Spectrum of the Vela Pulsar
R. P. Mignani; S. Zharikov; P. A. Caraveo
2007-07-13
Our knowledge of the optical spectra of Isolated Neutron Stars (INSs) is limited by their intrinsic faintness. Among the fourteen optically identified INSs, medium resolution spectra have been obtained only for a handful of objects. No spectrum has been published yet for the Vela pulsar (PSR B0833-45), the third brightest (V=23.6) INS with an optical counterpart. Optical multi-band photometry underlines a flat continuum.In this work we present the first optical spectroscopy observations of the Vela pulsar, performed in the 4000-11000 A spectral range.Our observations have been performed at the ESO VLT using the FORS2 instrument. The spectrum of the Vela pulsar is characterized by a flat power-law (alpha = -0.04 +/- 0.04), which compares well with the values obtained from broad-band photometry. This confirms, once more, that the optical emission of Vela is entirely of magnetospheric origin. The comparison between the optical spectral indeces of rotation-powered INSs does not show evidence for a spectral evolution suggesting that, as in the X-rays, the INS aging does not affect the spectral properties of the magnetospheric emission. At the same time, the optical spectral indeces are found to be nearly always flatter then the X-rays ones, clearly suggesting a general spectral turnover at lower energies.
Lisiecka, D. M.; Holt, R.; Tait, R.; Ford, M.; Lai, M.-C.; Chura, L. R.; Baron-Cohen, S.; Spencer, M. D.; Suckling, J.
2015-03-17
During adolescence, white matter microstructure undergoes an important stage of development. It is hypothesized that the alterations of brain connectivity that have a key role in autism spectrum conditions (ASCs) may interact with the development...
Computing High Accuracy Power Spectra with Pico
William A. Fendt; Benjamin D. Wandelt
2007-12-02
This paper presents the second release of Pico (Parameters for the Impatient COsmologist). Pico is a general purpose machine learning code which we have applied to computing the CMB power spectra and the WMAP likelihood. For this release, we have made improvements to the algorithm as well as the data sets used to train Pico, leading to a significant improvement in accuracy. For the 9 parameter nonflat case presented here Pico can on average compute the TT, TE and EE spectra to better than 1% of cosmic standard deviation for nearly all $\\ell$ values over a large region of parameter space. Performing a cosmological parameter analysis of current CMB and large scale structure data, we show that these power spectra give very accurate 1 and 2 dimensional parameter posteriors. We have extended Pico to allow computation of the tensor power spectrum and the matter transfer function. Pico runs about 1500 times faster than CAMB at the default accuracy and about 250,000 times faster at high accuracy. Training Pico can be done using massively parallel computing resources, including distributed computing projects such as Cosmology@Home. On the homepage for Pico, located at http://cosmos.astro.uiuc.edu/pico, we provide new sets of regression coefficients and make the training code available for public use.
Directional detection of galactic dark matter
Mayet, F; Santos, D
2012-01-01
Directional detection is a promising Dark Matter search strategy. Taking advantage on the rotation of the Solar system around the galactic center through the Dark Matter halo, it allows to show a direction dependence of WIMP events that may be a powerful tool to identify genuine WIMP events as such. Directional detection strategy requires the simultaneous measurement of the energy and the 3D track of low energy recoils, which is a common challenge for all current projects of directional detectors.
Gao-Chan Yong
2015-12-18
It is generally considered that an atomic nucleus is always compact. Based on the isospin-dependent Boltzmann nuclear transport model, here I show that large block nuclear matter or excited nuclear matter may both be hollow. And the size of inner bubble in these matter is affected by the charge number of nuclear matter. Existence of hollow nuclear matter may have many implications in nuclear or atomic physics or astrophysics as well as some practical applications.
Yong, Gao-Chan
2015-01-01
It is generally considered that an atomic nucleus is always compact. Based on the isospin-dependent Boltzmann nuclear transport model, here I show that large block nuclear matter or excited nuclear matter may both be hollow. And the size of inner bubble in these matter is affected by the charge number of nuclear matter. Existence of hollow nuclear matter may have many implications in nuclear or atomic physics or astrophysics as well as some practical applications.
Broad-Spectrum Antiviral Therapeutics
Rider, Todd H.
Currently there are relatively few antiviral therapeutics, and most which do exist are highly pathogen-specific or have other disadvantages. We have developed a new broad-spectrum antiviral approach, dubbed Double-stranded ...
Spectrum of C_heart where 1 + z + 2\\sqrt{1 - z^2} heart(z)= ------------------------- 3 - z + 2\\sqrt{1 - z^2}. Figure 7.1, page 303, of "Composition Operators on Spaces ...
Constraining dark matter late-time energy injection: decays and p-wave annihilations
Diamanti, Roberta; Mena, Olga; Palomares-Ruiz, Sergio; Vincent, Aaron C. [Instituto de Física Corpuscular (IFIC), CSIC-Universitat de Valčncia, Apartado de Correos 22085, E-46071 Valencia (Spain); Lopez-Honorez, Laura, E-mail: R.Diamanti@uva.nl, E-mail: llopezho@vub.ac.be, E-mail: omena@ific.uv.es, E-mail: sergio.palomares.ruiz@ific.uv.es, E-mail: vincent@ific.uv.es [Theoretische Natuurkunde Vrije Universiteit Brussel and The International Solvay Institutes Pleinlaan 2, B-1050 Brussels (Belgium)
2014-02-01
We use the latest cosmic microwave background (CMB) observations to provide updated constraints on the dark matter lifetime as well as on p-wave suppressed annihilation cross sections in the 1 MeV to 1 TeV mass range. In contrast to scenarios with an s-wave dominated annihilation cross section, which mainly affect the CMB close to the last scattering surface, signatures associated with these scenarios essentially appear at low redshifts (z?<50) when structure began to form, and thus manifest at lower multipoles in the CMB power spectrum. We use data from Planck, WMAP9, SPT and ACT, as well as Lyman–? measurements of the matter temperature at z ? 4 to set a 95% confidence level lower bound on the dark matter lifetime of ? 4 × 10{sup 25} s for m{sub ?} = 100 MeV. This bound becomes lower by an order of magnitude at m{sub ?} = 1 TeV due to inefficient energy deposition into the intergalactic medium. We also show that structure formation can enhance the effect of p-wave suppressed annihilation cross sections by many orders of magnitude with respect to the background cosmological rate, although even with this enhancement, CMB constraints are not yet strong enough to reach the thermal relic value of the cross section.
Lyapunov spectrum of granular gases
McNamara, Sean; Mareschal, Michel
2001-06-01
We calculate and study the Lyapunov spectrum of a granular gas maintained in a steady state by an isokinetic thermostat. Considering restitution coefficients greater than unity allows us to show that the spectra change smoothly and continuously at equilibrium. The shearing instability of the granular gas, however, provokes an abrupt change in the structure of the spectrum. The relationship between various physically relevant quantities and the energy dissipation rate differs from previously studied nonequilibrium steady states.
A Couplet from Flavored Dark Matter
Prateek Agrawal; Zackaria Chacko; Can Kilic; Christopher B. Verhaaren
2015-03-10
We show that a couplet, a pair of closely spaced photon lines, in the X-ray spectrum is a distinctive feature of lepton flavored dark matter models for which the mass spectrum is dictated by Minimal Flavor Violation. In such a scenario, mass splittings between different dark matter flavors are determined by Standard Model Yukawa couplings and can naturally be small, allowing all three flavors to be long-lived and contribute to the observed abundance. Then, in the presence of a tiny source of flavor violation, heavier dark matter flavors can decay via a dipole transition on cosmological timescales, giving rise to three photon lines. The ratios of the line energies are completely determined in terms of the charged lepton masses, and constitute a firm prediction of this framework. For dark matter masses of order the weak scale, the couplet lies in the keV-MeV region, with a much weaker line in the eV-keV region. This scenario constitutes a potential explanation for the recent claim of the observation of a 3.5 keV line. The next generation of X-ray telescopes may have the necessary resolution to resolve the double line structure of such a couplet.
A Couplet from Flavored Dark Matter
Agrawal, Prateek; Kilic, Can; Verhaaren, Christopher B
2015-01-01
We show that a couplet, a pair of closely spaced photon lines, in the X-ray spectrum is a distinctive feature of lepton flavored dark matter models for which the mass spectrum is dictated by Minimal Flavor Violation. In such a scenario, mass splittings between different dark matter flavors are determined by Standard Model Yukawa couplings and can naturally be small, allowing all three flavors to be long-lived and contribute to the observed abundance. Then, in the presence of a tiny source of flavor violation, heavier dark matter flavors can decay via a dipole transition on cosmological timescales, giving rise to three photon lines. The ratios of the line energies are completely determined in terms of the charged lepton masses, and constitute a firm prediction of this framework. For dark matter masses of order the weak scale, the couplet lies in the keV-MeV region, with a much weaker line in the eV-keV region. This scenario constitutes a potential explanation for the recent claim of the observation of a 3.5 ke...
A model of the directional sensitivity of low-pressure CF? dark matter detectors
Deaconu, Cosmin ?tefan
2015-01-01
Identification of the composition of dark matter is one of the major unsolved puzzles in modern physics. Detectors with sensitivity to the direction of certain classes of dark matter particles have potentially very powerful ...
Analysis of Wind Power and Load Data at Multiple Time Scales
Coughlin, Katie
2011-01-01
The spectrum of power from wind turbines. Journal of PowerAWEA 2010. American Wind Energy Association ProjectsErik and Jason Kemper. 2009. Wind Plant Ramping Behavior.
Calibration Guide Agilent Technologies ESA Spectrum Analyzers
Anlage, Steven
Calibration Guide Agilent Technologies ESA Spectrum Analyzers This manual provides documentation periodically. For the latest information about Agilent ESA Spectrum Analyzers, including firmware upgrades
ACCURATE UNIVERSAL MODELS FOR THE MASS ACCRETION HISTORIES AND CONCENTRATIONS OF DARK MATTER HALOS
Zhao, D. H.; Jing, Y. P.; Mo, H. J.; Boerner, G.
2009-12-10
A large amount of observations have constrained cosmological parameters and the initial density fluctuation spectrum to a very high accuracy. However, cosmological parameters change with time and the power index of the power spectrum dramatically varies with mass scale in the so-called concordance LAMBDACDM cosmology. Thus, any successful model for its structural evolution should work well simultaneously for various cosmological models and different power spectra. We use a large set of high-resolution N-body simulations of a variety of structure formation models (scale-free, standard CDM, open CDM, and LAMBDACDM) to study the mass accretion histories, the mass and redshift dependence of concentrations, and the concentration evolution histories of dark matter halos. We find that there is significant disagreement between the much-used empirical models in the literature and our simulations. Based on our simulation results, we find that the mass accretion rate of a halo is tightly correlated with a simple function of its mass, the redshift, parameters of the cosmology, and of the initial density fluctuation spectrum, which correctly disentangles the effects of all these factors and halo environments. We also find that the concentration of a halo is strongly correlated with the universe age when its progenitor on the mass accretion history first reaches 4% of its current mass. According to these correlations, we develop new empirical models for both the mass accretion histories and the concentration evolution histories of dark matter halos, and the latter can also be used to predict the mass and redshift dependence of halo concentrations. These models are accurate and universal: the same set of model parameters works well for different cosmological models and for halos of different masses at different redshifts, and in the LAMBDACDM case the model predictions match the simulation results very well even though halo mass is traced to about 0.0005 times the final mass, when cosmological parameters and the power index of the initial density fluctuation spectrum have changed dramatically. Our model predictions also match the PINOCCHIO mass accretion histories very well, which are much independent of our numerical simulations and our definitions of halo merger trees. These models are also simple and easy to implement, making them very useful in modeling the growth and structure of dark matter halos. We provide appendices describing the step-by-step implementation of our models. A calculator which allows one to interactively generate data for any given cosmological model is provided on the Web, together with a user-friendly code to make the relevant calculations and some tables listing the expected concentration as a function of halo mass and redshift in several popular cosmological models. We explain why LAMBDACDM and open CDM halos on nearly all mass scales show two distinct phases in their mass growth histories. We discuss implications of the universal relations we find in connection to the formation of dark matter halos in the cosmic density field.
Effect of resonance broadening on the evolution of the edge of a turbulent spectrum
Karney, Charles
-hybridwave spectrum is investigated. This narrowing is of concern because it could make control of lower-hybrid heating difficult. It is shown numerically, however, that relatively uniform spatial power deposition
A new approach to automatic radiation spectrum analysis
Olmos, P.; Diaz, J.C.; Perez, J.M.; Aguayo, P.; Bru, A.; Garcia-Belmonte, G.; de Pablos, J.L. ); Gomez, P.; Rodellar, V. )
1991-08-01
In this paper the application of adaptive methods to the solution of the automatic radioisotope identification problem using the energy spectrum is described. The identification is carried out by means of neural networks, which allow the use of relatively reduced computational structures, while keeping high pattern recognition capability. In this context, it has been found that one of these simple structures, once adequately trained, is quite suitable to identify a given isotope present in a mixture of elements as well as the relative proportions of each identified substance. Preliminary results are good enough to consider these adaptive structures as powerful and simple tools in the automatic spectrum analysis.
The AMS-02 Transition Radiation Detector to Search for Dark Matter in Space
Roma "La Sapienza", Universitŕ di
The AMS-02 Transition Radiation Detector to Search for Dark Matter in Space Francesca Bucci) to measure the primary cosmic rays spectrum in space. A Transition Radiation Detector (TRD) will provide in the energy range of interest. Index Terms-- Transition radiation detector, straw tubes, gas gain, dark matter
Kumar, Jason
2014-06-24
We review the theoretical framework underlying models of asymmetric dark matter, describe astrophysical constraints which arise from observations of neutron stars, and discuss the prospects for detecting asymmetric dark matter.
Knaian, Ara N. (Ara Nerses), 1977-
2008-01-01
Programmable matter is a proposed digital material having computation, sensing, actuation, and display as continuous properties active over its whole extent. Programmable matter would have many exciting applications, like ...
Center symmetry and Hagedorn spectrum
Cohen, Thomas D
2015-01-01
This paper explores the conjecture that large $N_c$ gauge theories have a Hagedorn spectrum, if, and only if, they are confining and posses an explicit or emergent center symmetry. Evidence in support of this conjecture is presented. Many classes of large $N_c$ gauge theories are considered. In all cases, we find that theories for which there exists a strong plausibility argument for a Hagedorn spectrum at large $N_c$ are also believed to be confining and possess either an explicit center symmetric or have a strong plausibility argument for the existence of an emergent center symmetry at large $N_c$. Conversely, all theories we considered which are believed not to have a Hagedorn spectrum at large $N_c$, either were known not to be confining or else were believed to lack an emergent center symmetry. This is consistent with expectations based on the conjecture.
Hot-dark matter, cold dark matter and accelerating universe
Abbas Farmany; Amin Farmany; Mohammad Mahmoodi
2006-07-07
The Friedman equation is solved for a universe contains hotdark matter and cold dark matter. In this scenario, hot-dark matter drives an accelerating universe no cold dark matter.
Luminosity Spectrum Reconstruction at Linear Colliders
Stéphane Poss; André Sailer
2014-04-11
A good knowledge of the luminosity spectrum is mandatory for many measurements at future e+e- colliders. As the beam-parameters determining the luminosity spectrum cannot be measured precisely, the luminosity spectrum has to be measured through a gauge process with the detector. The measured distributions, used to reconstruct the spectrum, depend on Initial State Radiation, cross-section, and Final State Radiation. To extract the basic luminosity spectrum, a parametric model of the luminosity spectrum is created, in this case the spectrum at the 3 TeV Compact Linear Collider (CLIC). The model is used within a reweighting technique to extract the luminosity spectrum from measured Bhabha event observables, taking all relevant effects into account. The centre-of-mass energy spectrum is reconstructed within 5% over the full validity range of the model. The reconstructed spectrum does not result in a significant bias or systematic uncertainty in the exemplary physics benchmark process of smuon pair production.
Spatially inhomogeneous condensate in asymmetric nuclear matter
A. Sedrakian
2001-01-03
We study the isospin singlet pairing in asymmetric nuclear matter with nonzero total momentum of the condensate Cooper pairs. The quasiparticle excitation spectrum is fourfold split compared to the usual BCS spectrum of the symmetric, homogeneous matter. A twofold splitting of the spectrum into separate branches is due to the finite momentum of the condensate, the isospin asymmetry, or the finite quasiparticle lifetime. The coupling of the isospin singlet and triplet paired states leads to further twofold splitting of each of these branches. We solve the gap equation numerically in the isospin singlet channel in the case where the pairing in the isospin triplet channel is neglected and find nontrivial solutions with finite total momentum of the pairs. The corresponding phase assumes a periodic spatial structure which carries a isospin density wave at constant total number of particles. The phase transition from the BCS to the inhomogeneous superconducting phase is found to be first order and occurs when the density asymmetry is increased above 0.25. The transition from the inhomogeneous superconducting to the unpaired normal state is second order. The maximal values of the critical total momentum (in units of the Fermi momentum) and the critical density asymmetry at which condensate disappears are $P_c/p_F = 0.3$ and $\\alpha_c = 0.41$. The possible spatial forms of the ground state of the inhomogeneous superconducting phase are briefly discussed.
Lincoln, Don
2013-12-05
Carl Sagan's oft-quoted statement that there are "billions and billions" of stars in the cosmos gives an idea of just how much "stuff" is in the universe. However scientists now think that in addition to the type of matter with which we are familiar, there is another kind of matter out there. This new kind of matter is called "dark matter" and there seems to be five times as much as ordinary matter. Dark matter interacts only with gravity, thus light simply zips right by it. Scientists are searching through their data, trying to prove that the dark matter idea is real. Fermilab's Dr. Don Lincoln tells us why we think this seemingly-crazy idea might not be so crazy after all.
Lincoln, Don
2014-08-07
Carl Sagan's oft-quoted statement that there are "billions and billions" of stars in the cosmos gives an idea of just how much "stuff" is in the universe. However scientists now think that in addition to the type of matter with which we are familiar, there is another kind of matter out there. This new kind of matter is called "dark matter" and there seems to be five times as much as ordinary matter. Dark matter interacts only with gravity, thus light simply zips right by it. Scientists are searching through their data, trying to prove that the dark matter idea is real. Fermilab's Dr. Don Lincoln tells us why we think this seemingly-crazy idea might not be so crazy after all.
Experimental spectrum of reactor antineutrinos and spectra of main fissile isotopes
Sinev, V. V., E-mail: vsinev@pcbai10.inr.ruhep.ru [Russian Academy of Sciences, Institute for Nuclear Research (Russian Federation)
2013-05-15
Within the period between the years 1988 and 1990, the spectrum of positrons from the inverse-beta-decay reaction on a proton was measured at the Rovno atomic power plant in the course of experiments conducted there. The measured spectrum has the vastest statistics in relation to other neutrino experiments at nuclear reactors and the lowest threshold for positron detection. An experimental reactor-antineutrino spectrum was obtained on the basis of this positron spectrum and was recommended as a reference spectrum. The spectra of individual fissile isotopes were singled out from the measured antineutrino spectrum. These spectra can be used to analyze neutrino experiments performed at nuclear reactors for various compositions of the fuel in the reactor core.
Power and spectrum efficient communications in wireless ad hoc networks
Qu, Qi
2008-01-01
in Electrical and Computer Engineering (Communication Theoryin Electrical Engineering (Communication Theory and Systems)in Electrical Engineering (Communication Theory and Systems)
Power and spectrum efficient communications in wireless ad hoc networks
Qu, Qi
2008-01-01
A. Bahai, “Energy-efficiency of MIMO and cooperative MIMOMIMO-based cooperative communication for energy-constrainedcooperation, cooperative MIMO can achieve better energy and
Geometry Matters | The Ames Laboratory
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverse (Journalvivo Low-Dose Low LET Ionizing RadiationSNACGeographyGeometry Matters
Wolf, Kirk
Foucault's Ethics of Power Kirk Wolf Delia College 1. I n t r o d u c t i o n Since Foucaull 's death in 19K4, his interpreters have generally located his importance in his genealogical critiques and in his phi losophy ofpower. On the one hand... critiques and his views on power remains a matter of dispute, for Foucault neither expressly states a program of critique, nor clearly articulates an account of power. The pur pose of this paper, then, is to establish the relationship between...
Non-Cooperative Spectrum Access -- The Dedicated vs. Free Spectrum Choice
Jagannathan, Krishna Prasanna
We consider a dynamic spectrum access system in which Secondary Users (SUs) choose to either acquire dedicated spectrum or to use spectrum-holes (white spaces) which belong to Primary Users (PUs). The trade-off incorporated ...
Galactic propagation of positrons from particle dark-matter annihilation
I. V. Moskalenko; A. W. Strong
1999-06-14
We have made a calculation of the propagation of positrons from dark-matter particle annihilation in the Galactic halo for different models of the dark matter halo distribution using our 3D code. We show that the Green's functions are not very sensitive to the dark matter distribution for the same local dark matter energy density. We compare our predictions with computed cosmic ray positron spectra ("background") for the "conventional" cosmic-ray nucleon spectrum which matches the local measurements, and a modified spectrum which respects the limits imposed by measurements of diffuse Galactic gamma-rays, antiprotons, and positrons. We conclude that significant detection of a dark matter signal requires favourable conditions and precise measurements unless the dark matter is clumpy which would produce a stronger signal. Although our conclusion qualitatively agrees with that of previous authors, it is based on a more realistic model of particle propagation and thus reduces the scope for future speculations. Reliable background evaluation requires new accurate positron measurements and further developments in modelling production and propagation of cosmic ray species in the Galaxy.
LyMAS: Predicting Large-Scale Lyman-alpha Forest Statistics from the Dark Matter Density Field
Peirani, Sébastien; Colombi, Stéphane; Blaizot, Jérémy; Dubois, Yohan; Pichon, Christophe
2013-01-01
[abridged] We describe LyMAS (Ly-alpha Mass Association Scheme), a method of predicting clustering statistics in the Ly-alpha forest on large scales from moderate resolution simulations of the dark matter distribution, with calibration from high-resolution hydrodynamic simulations of smaller volumes. We use the "Horizon MareNostrum" simulation, a 50 Mpc/h comoving volume evolved with the adaptive mesh hydrodynamic code RAMSES, to compute the conditional probability distribution P(F_s|delta_s) of the transmitted flux F_s, smoothed (1-dimensionally) over the spectral resolution scale, on the dark matter density contrast delta_s, smoothed (3-dimensionally) over a similar scale. In this study we adopt the spectral resolution of the SDSS-III BOSS at z=2.5, and we find optimal results for a dark matter smoothing length sigma=0.3 Mpc/h (comoving). In extended form, LyMAS exactly reproduces both the 1-dimensional power spectrum and 1-point flux distribution of the hydro simulation spectra. Applied to the MareNostrum ...
Statistical Tools for Analyzing the Cosmic Ray Energy Spectrum
J. D. Hague; B. R. Becker; M. S. Gold; J. A. J. Matthews
2008-08-20
In this paper un-binned statistical tools for analyzing the cosmic ray energy spectrum are developed and illustrated with a simulated data set. The methods are designed to extract accurate and precise model parameter estimators in the presence of statistical and systematic energy errors. Two robust methods are used to test for the presence of flux suppression at the highest energies: the Tail-Power statistic and a likelihood ratio test. Both tests give evidence of flux suppression in the simulated data. The tools presented can be generalized for use on any astrophysical data set where the power-law assumption is relevant and can be used to aid observational design.
Yousef Ghazi-Tabatabai
2012-11-19
While Quantum Gravity remains elusive and Quantum Field Theory retains the interpretational difficulties of Quantum Mechanics, we have introduced an alternate approach to the unification of particles, fields, space and time, suggesting that the concept of matter as space without time provides a framework which unifies matter with spacetime and in which we anticipate the development of complete theories (ideally a single unified theory) describing observed 'particles, charges, fields and forces' solely with the geometry of our matter-space-time universe.
Load Management and Houston Lighting and Power Co.
Drawe, R. G.; Ramsay, I. M.
1984-01-01
Defining Load Management as influencing of customer loads in order to shift the time use of electric power and energy, encompasses a broad spectrum of activities at Houston Lighting & Power Company. This paper describes those activities by directing...
Fermion dark matter from SO(10)
Carolina Arbelaez; Robinson Longas; Diego Restrepo; Oscar Zapata
2015-09-21
We construct and analyze non-supersymmetric SO(10) standard model extensions which explain dark matter (DM) through the fermionic Higgs portal. In these SO(10)-based models the DM particle is naturally stable since a $Z_2$ discrete symmetry, the matter parity, is left at the end of the symmetry breaking chain to the standard model. Potentially realistic models contain the $\\bf{10}$ and $\\bf{45}$ fermionic representations from which a neutralino-like mass matrix with arbitrary mixings can be obtained. Two different SO(10) breaking chains will be analyzed in light of gauge coupling unification: the standard path $\\text{SU}(5)\\times U(1)_{X}$ and the left-right symmetry intermediate chain. The former opens the possibility of a split supersymmetric-like spectrum with an additional (inert) scalar doublet, while the later requires additional exotic scalar representations associated to the breaking of the left-right symmetry.
Chamseddine, Ali H.; Mukhanov, Viatcheslav; Vikman, Alexander E-mail: viatcheslav.Mukhanov@lmu.de
2014-06-01
We consider minimal extensions of the recently proposed Mimetic Dark Matter and show that by introducing a potential for the mimetic non-dynamical scalar field we can mimic nearly any gravitational properties of the normal matter. In particular, the mimetic matter can provide us with inflaton, quintessence and even can lead to a bouncing nonsingular universe. We also investigate the behaviour of cosmological perturbations due to a mimetic matter. We demonstrate that simple mimetic inflation can produce red-tilted scalar perturbations which are largely enhanced over gravity waves.
Broader source: Energy.gov [DOE]
This edition of the mailbag tackles follow-up questions from our Energy Matters discussion on breaking our reliance on foreign oil.
Luc Blanchet; Lavinia Heisenberg
2015-05-19
Massive gravity theories have been developed as viable IR modifications of gravity motivated by dark energy and the problem of the cosmological constant. On the other hand, modified gravity and modified dark matter theories were developed with the aim of solving the problems of standard cold dark matter at galactic scales. Here we propose to adapt the framework of ghost-free massive bigravity theories to reformulate the problem of dark matter at galactic scales. We investigate a promising alternative to dark matter called dipolar dark matter (DDM) in which two different species of dark matter are separately coupled to the two metrics of bigravity and are linked together by an internal vector field. We show that this model successfully reproduces the phenomenology of dark matter at galactic scales (i.e. MOND) as a result of a mechanism of gravitational polarisation. The model is safe in the gravitational sector, but because the two types of dark matter interact through the vector field, a ghostly degree of freedom in the decoupling limit is reintroduced in the dark matter sector. Crucial questions to address in future work is whether the polarisation mechanism can be realized in absence of ghosts, and what are the cosmological implications of the model.
ON THE ORIGIN OF THE 1/f SPECTRUM IN THE SOLAR WIND MAGNETIC FIELD
Verdini, Andrea [Solar-Terrestrial Center of Excellence-SIDC, Royal Observatory of Belgium, Bruxelles (Belgium); Grappin, Roland [LUTH, Observatoire de Paris, CNRS, Universite Paris-Diderot, 92190 Meudon (France); Pinto, Rui [Laboratoire AIM Paris-Saclay, CEA/Irfu, and Universite Paris-Diderot CNRS/INSU, Gis-sur-Yvette (France); Velli, Marco, E-mail: verdini@oma.be, E-mail: Roland.Grappin@obspm.fr, E-mail: rui.pinto@cea.fr, E-mail: mvelli@jpl.nasa.gov [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA (United States)
2012-05-10
We present a mechanism for the formation of the low-frequency 1/f magnetic spectrum based on numerical solutions of a shell-reduced MHD model of the turbulent dynamics inside the sub-Alfvenic solar wind. We assign reasonably realistic profiles to the wind speed and the density along the radial direction, and a radial magnetic field. Alfven waves of short periodicity (600 s) are injected at the base of the chromosphere, penetrate into the corona, and are partially reflected, thus triggering a turbulent cascade. The cascade is strong for the reflected wave while it is weak for the outward propagating waves. Reflection at the transition region recycles the strong turbulent spectrum into the outward weak spectrum, which is advected beyond the Alfvenic critical point without substantial evolution. There, the magnetic field has a perpendicular power-law spectrum with slope close to the Kolmogorov -5/3. The parallel spectrum is inherited from the frequency spectrum of large (perpendicular) eddies. The shape is a double power law with slopes of {approx_equal} - 1 and -2 at low and high frequencies, respectively, with the position of the break depending on the injected spectrum. We suggest that the double power-law spectrum measured by Helios at 0.3 AU, where the average magnetic field is not aligned with the radial (contrary to our assumptions), results from the combination of such different spectral slopes. At low frequency the parallel spectrum dominates with its characteristic 1/f shape, while at higher frequencies its steep spectral slope (-2) is masked by the more energetic perpendicular spectrum (slope -5/3).
Energy-Aware Spectrum Sensing in Cognitive Wireless Sensor Networks: a Cross Layer Approach
Shihada, Basem
Energy-Aware Spectrum Sensing in Cognitive Wireless Sensor Networks: a Cross Layer Approach Luca-power wireless motes [6] and thus introduces significant energy overhead. In order to meet power constraints Stabellini and Jens Zander Wireless@KTH, The Royal Institute of Technology, Electrum 418, SE-164 40 Kista
Distributed TV Spectrum Allocation for Cognitive Cellular Network under Game Theoretical
Gross, James
of TV stations and white base stations, maximum permitted transmit power levels on all channels for each station needs to choose a channel with the maximal permitted power on that channel such that the resulting cellular base stations to utilize TV white spectrum (such base stations referred to as white base stations
Incompressibility of asymmetric nuclear matter
Lie-Wen Chen; Bao-Jun Cai; Chun Shen; Che Ming Ko; Jun Xu; Bao-An Li
2009-11-17
The incompressibility $K_sat(\\delta)$ of isospin asymmetric nuclear matter at its saturation density. Our results show that in the expansion of $K_sat(\\delta)$ in powers of isospin asymmetry $\\delta$, i.e., $K_sat(\\delta )$=K_{0}+K_{sat,2}\\delta^{2}+K_{sat,4}\\delta^{4}+O(\\delta^{6})$, the magnitude of the 4th-order K_{sat,4} parameter is generally small. The 2nd-order K_{sat,2} parameter thus essentially characterizes the isospin dependence of the incompressibility of asymmetric nuclear matter at saturation density. Furthermore, the K_{sat,2} can be expressed as K_{sat,2}=K_{sym}-6L-J_{0}/{K_{0}L in terms of the slope parameter $L$ and the curvature parameter $K_{\\mathrm{sym}}$ of the symmetry energy and the third-order derivative parameter $J_0$ of the energy of symmetric nuclear matter at saturation density, and we find the higher order $J_0$ contribution to K_{sat,2} generally cannot be neglected. Also, we have found a linear correlation between K_{sym} and $L$ as well as between $J_{0}/K_{0}$ and $K_{0}$. Using these correlations together with the empirical constraints on $K_{0}$ and $L$, the nuclear symmetry energy $E_sym(\\rho_{0})$ at normal nuclear density, and the nucleon effective mass, we have obtained an estimated value of K_{sat,2}=-370 +- 120 MeV for the 2nd-order parameter in the isospin asymmetry expansion of the incompressibility of asymmetric nuclear matter at its saturation density.
On the Oscillation of Neutrinos Produced by the Annihilation of Dark Matter inside the Sun
Arman Esmaili; Yasaman Farzan
2010-06-14
The annihilation of dark matter particles captured by the Sun can lead to a neutrino flux observable in neutrino detectors. Considering the fact that these dark matter particles are non-relativistic, if a pair of dark matter annihilates to a neutrino pair, the spectrum of neutrinos will be monochromatic. We show that in this case, even after averaging over production point inside the Sun, the oscillatory terms of the oscillation probability do not average to zero. This leads to interesting observable features in the annual variation of the number of muon track events. We show that smearing of the spectrum due to thermal distribution of dark matter inside the Sun is too small to wash out this variation. We point out the possibility of studying the initial flavor composition of neutrinos produced by the annihilation of dark matter particles via measuring the annual variation of the number of muon-track events in neutrino telescopes.
A new life for sterile neutrinos: resolving inconsistencies using hot dark matter
Hamann, Jan; Hasenkamp, Jasper E-mail: jasper.hasenkamp@nyu.edu
2013-10-01
Within the standard ?CDM model of cosmology, the recent Planck measurements have shown discrepancies with other observations, e.g., measurements of the current expansion rate H{sub 0}, the galaxy shear power spectrum and counts of galaxy clusters. We show that if ?CDM is extended by a hot dark matter component, which could be interpreted as a sterile neutrino, the data sets can be combined consistently. A combination of Planck data, WMAP-9 polarisation data, measurements of the BAO scale, the HST measurement of H{sub 0}, Planck galaxy cluster counts and galaxy shear data from the CFHTLens survey yields ?N{sub eff} = 0.61±0.30 and m{sub s}{sup eff} = (0.41±0.13)eV at 1?. The former is driven mainly by the large H{sub 0} of the HST measurement, while the latter is driven by cluster data. CFHTLens galaxy shear data prefer ?N{sub eff}> 0 and a non-zero mass. Taken together, we find hints for the presence of a hot dark matter component at 3?. A sterile neutrino motivated by the reactor and gallium anomalies appears rejected at even higher significance and an accelerator anomaly sterile neutrino is found in tension at 2?.
An antenna for directional detection of WISPy dark matter
Jaeckel, Joerg; Redondo, Javier E-mail: redondo@mpp.mpg.de
2013-11-01
It is an intriguing possibility that the cold dark matter of the Universe may consist of very light and very weakly interacting particles such as axion(-like particles) and hidden photons. This opens up (but also requires) new techniques for direct detection. One possibility is to use reflecting surfaces to facilitate the conversion of dark matter into photons, which can be concentrated in a detector with a suitable geometry. In this note we show that this technique also allows for directional detection and inference of the full vectorial velocity spectrum of the dark matter particles. We also note that the non-vanishing velocity of dark matter particles is relevant for the conception of (non-directional) discovery experiments and outline relevant features.
Gobato, Ricardo; Fedrigo, Desire Francine Gobato
2015-01-01
Our work is an approach between matter and energy. Using the famous equation E = mc^2, Einstein and the Law of Universal Gravitation of Newton, we estimate that a small amount matter converted into energy is needed to lift, using the gravitational potential energy equation on the surface, a mountain of solid iron or even Mount Everest.
Joe Sato; Masafumi Koike; Toshihiko Ota; Masako Saito
2008-10-17
We study the parametric resonance of the neutrino oscillation through the matter whose density varies spatially. The Fourier analysis of the matter effect enables us to clarify the parametric resonance condition, which is summarized in a frequency matching between the neutrino oscillation and the spatial variation of the matter density. As a result, the n-th Fourier mode of a matter density profile modifies the energy spectrum of the nu_mu -> nu_e appearance probability at around the n-th dip.
Hybrid spread spectrum radio system
Smith, Stephen F. (London, TN); Dress, William B. (Camas, WA)
2010-02-02
Systems and methods are described for hybrid spread spectrum radio systems. A method includes modulating a signal by utilizing a subset of bits from a pseudo-random code generator to control an amplification circuit that provides a gain to the signal. Another method includes: modulating a signal by utilizing a subset of bits from a pseudo-random code generator to control a fast hopping frequency synthesizer; and fast frequency hopping the signal with the fast hopping frequency synthesizer, wherein multiple frequency hops occur within a single data-bit time.
Baudis, Laura
2015-01-01
One of the major challenges of modern physics is to decipher the nature of dark matter. Astrophysical observations provide ample evidence for the existence of an invisible and dominant mass component in the observable universe, from the scales of galaxies up to the largest cosmological scales. The dark matter could be made of new, yet undiscovered elementary particles, with allowed masses and interaction strengths with normal matter spanning an enormous range. Axions, produced non-thermally in the early universe, and weakly interacting massive particles (WIMPs), which froze out of thermal equilibrium with a relic density matching the observations, represent two well-motivated, generic classes of dark matter candidates. Dark matter axions could be detected by exploiting their predicted coupling to two photons, where the highest sensitivity is reached by experiments using a microwave cavity permeated by a strong magnetic field. WIMPs could be directly observed via scatters off atomic nuclei in underground, ultr...
P. Sikivie
2009-09-04
The hypothesis of an `invisible' axion was made by Misha Shifman and others, approximately thirty years ago. It has turned out to be an unusually fruitful idea, crossing boundaries between particle physics, astrophysics and cosmology. An axion with mass of order $10^{-5}$ eV (with large uncertainties) is one of the leading candidates for the dark matter of the universe. It was found recently that dark matter axions thermalize and form a Bose-Einstein condensate (BEC). Because they form a BEC, axions differ from ordinary cold dark matter (CDM) in the non-linear regime of structure formation and upon entering the horizon. Axion BEC provides a mechanism for the production of net overall rotation in dark matter halos, and for the alignment of cosmic microwave anisotropy multipoles. Because there is evidence for these phenomena, unexplained with ordinary CDM, an argument can be made that the dark matter is axions.
Hermano Velten; Dominik J. Schwarz
2012-10-01
Fluids often display dissipative properties. We explore dissipation in the form of bulk viscosity in the cold dark matter fluid. We constrain this model using current data from supernovae, baryon acoustic oscillations and the cosmic microwave background. Considering the isotropic and homogeneous background only, viscous dark matter is allowed to have a bulk viscosity $\\lesssim 10^7$ Pa$\\cdot$s, also consistent with the expected integrated Sachs-Wolfe effect (which plagues some models with bulk viscosity). We further investigate the small-scale formation of viscous dark matter halos, which turns out to place significantly stronger constraints on the dark matter viscosity. The existence of dwarf galaxies is guaranteed only for much smaller values of the dark matter viscosity, $\\lesssim 10^{-3}$ Pa$\\cdot$s.
Determination of a mutational spectrum
Thilly, William G. (Winchester, MA); Keohavong, Phouthone (Cambridge, MA)
1991-01-01
A method of resolving (physically separating) mutant DNA from nonmutant DNA and a method of defining or establishing a mutational spectrum or profile of alterations present in nucleic acid sequences from a sample to be analyzed, such as a tissue or body fluid. The present method is based on the fact that it is possible, through the use of DGGE, to separate nucleic acid sequences which differ by only a single base change and on the ability to detect the separate mutant molecules. The present invention, in another aspect, relates to a method for determining a mutational spectrum in a DNA sequence of interest present in a population of cells. The method of the present invention is useful as a diagnostic or analytical tool in forensic science in assessing environmental and/or occupational exposures to potentially genetically toxic materials (also referred to as potential mutagens); in biotechnology, particularly in the study of the relationship between the amino acid sequence of enzymes and other biologically-active proteins or protein-containing substances and their respective functions; and in determining the effects of drugs, cosmetics and other chemicals for which toxicity data must be obtained.
Relativistic Laser-Matter Interactions
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Relativistic Laser-Matter Interactions Relativistic Laser-Matter Interactions Enabling the next generation of intense particle accelerators Contact Juan Fernandez (505) 667-6575...
Z. I. Tsvetanov; G. F. Hartig; H. C. Ford; G. A. Kriss; M. A. Dopita; L. L. Dressel; R. J. Harms
1998-01-06
The nuclear spectrum of M87 covering the Ly_a-H_a wavelength range was obtained with the HST Faint Object Spectrograph (FOS) trough a 0.21 arcsec aperture. Contrary to some previous claims, a single power law (F(nu)~nu^(-a)) can not reproduce the observed continuum shape and at least a broken power law is require for a good fit (a = 1.75 and 1.41 shortward and longward of the break at ~4500 A). We detect a set of broad (FWHM ~ 400 km/s) absorption lines arising in the gas associated with M87. These are only lines from neutral and very low ionization species blueshifted by ~150 km/s relative to the M87 systemic velocity, indicating a net gas outflow and turbulence. The excitation sensitive emission line ratios suggest that shocks may be the dominant energy supplier. The nuclear source in M87 is significantly variable. From the FOS target acquisition data, we have established that the flux from the optical nucleus varies by a factor ~2 on time scales of ~2.5 months and by as much as 25% over 3 weeks, and remains unchanged (<2.5%) on time scales of ~1 day. These timescales limit the physical size of the emitting region to a few hundred gravitational radii. The variability, combined with other observed spectral properties, strongly suggest that M87 is intrinsically of BL Lac type but is viewed at an angle too large to reveal the classical BL Lac properties.
Erken, Ozgur; Tam, Heywood; Yang, Qiaoli
2011-01-01
Cold dark matter axions thermalize through gravitational self-interactions and form a Bose-Einstein condensate when the photon temperature reaches approximately 500 eV. Axion Bose-Einstein condensation provides an opportunity to distinguish axions from the other dark matter candidates on the basis of observation. The rethermalization of axions that are about to fall in a galactic potential well causes them to acquire net overall rotation, whereas ordinary cold dark matter falls in with an irrotational velocity field. The inner caustics of galactic halos are different in the two cases.
Ozgur Erken; Pierre Sikivie; Heywood Tam; Qiaoli Yang
2011-11-16
Cold dark matter axions thermalize through gravitational self-interactions and form a Bose-Einstein condensate when the photon temperature reaches approximately 500 eV. Axion Bose-Einstein condensation provides an opportunity to distinguish axions from the other dark matter candidates on the basis of observation. The rethermalization of axions that are about to fall in a galactic potential well causes them to acquire net overall rotation, whereas ordinary cold dark matter falls in with an irrotational velocity field. The inner caustics of galactic halos are different in the two cases.
Marc Schumann
2015-01-06
This article gives an overview on the status of experimental searches for dark matter at the end of 2014. The main focus is on direct searches for weakly interacting massive particles (WIMPs) using underground-based low-background detectors, especially on the new results published in 2014. WIMPs are excellent dark matter candidates, predicted by many theories beyond the standard model of particle physics, and are expected to interact with the target nuclei either via spin-independent (scalar) or spin-dependent (axial-vector) couplings. Non-WIMP dark matter candidates, especially axions and axion-like particles are also briefly discussed.
SAW correlator spread spectrum receiver
Brocato, Robert W
2014-04-01
A surface acoustic wave (SAW) correlator spread-spectrum (SS) receiver is disclosed which utilizes a first demodulation stage with a chip length n and a second demodulation stage with a chip length m to decode a transmitted SS signal having a code length l=n.times.m which can be very long (e.g. up to 2000 chips or more). The first demodulation stage utilizes a pair of SAW correlators which demodulate the SS signal to generate an appropriate code sequence at an intermediate frequency which can then be fed into the second demodulation stage which can be formed from another SAW correlator, or by a digital correlator. A compound SAW correlator comprising two input transducers and a single output transducer is also disclosed which can be used to form the SAW correlator SS receiver, or for use in processing long code length signals.
FLUCTUATION DYNAMO AT FINITE CORRELATION TIMES AND THE KAZANTSEV SPECTRUM
Bhat, Pallavi; Subramanian, Kandaswamy, E-mail: palvi@iucaa.ernet.in [IUCAA, Post Bag 4, Ganeshkhind, Pune 411007 (India)
2014-08-20
Fluctuation dynamos are generic to astrophysical systems. The only analytical model of the fluctuation dynamo is the Kazantsev model which assumes a velocity field that is delta-correlated in time. We derive a generalized model of fluctuation dynamos with finite correlation time, ?, using renovating flows. For ? ? 0, we recover the standard Kazantsev equation for the evolution of longitudinal magnetic correlation, M{sub L} . To the next order in ?, the generalized equation involves third and fourth spatial derivatives of M{sub L} . It can be recast to one with at most second derivatives of M{sub L} using the Landau-Lifschitz approach. Remarkably, we then find that the magnetic power spectrum remains the Kazantsev spectrum of M(k)?k {sup 3/2}, in the large k limit, independent of ?.
Photonic dark matter portal revisited
S. A. Alavi; F S Kazemian
2015-11-18
In our previous paper [1], we studied a model of dark matter (DM) in which the hidden sector interacts with standard model particles via a hidden photonic portal (HP). We investigated the effects of this new interaction on the hydrogen atom and obtained an upper bound for the coupling of the model. In this work, we study the effects of HP on two interesting exotic atoms namely muonium and positronium. We obtain a tighter upper limit on the coupling. We also calculate the change (shift) in the Aharonov-Bohm phase due to HP and find that the phase shift is negligibly small (for DM particles mass in the GeV range). Recently a 3.5 keV X ray line signal observed in the spectrum of 73 galaxy clusters, reported by the XXM-Newton X ray observatory. Since in HP model the DM particles can decay directly into photons, so we finally calculate the value of the coupling constant f using the condition Delta E=3.5 keV.
Matter & Energy Civil Engineering
Rogers, John A.
See Also: Matter & Energy Detectors· Optics· Civil Engineering· Engineering· Nature of Water Yonggang Huang, Joseph Cummings Professor of Civil and Environmental Engineering and Mechanical Engineering· Electronics· Reference Photography· Infrared· Mechanical engineering · Optics· ScienceDaily (Jan. 17, 2011
Martoff, C. J.
Dark matter (DM) detectors with directional sensitivity have the potential of yielding an unambiguous positive observation of WIMPs as well as discriminating between galactic DM halo models. In this paper, we introduce the ...
Suslick, Kenneth S.
See also: Matter & Energy Detectors· Electronics· Technology· Medical Technology· Weapons Technology · Organic Chemistry· Reference Hydrogen chloride· Photography· Catalytic converter· Nanomedicine a series of tiny colored dots each a different pigment on an inert backing such as paper, plastic
Rohini M. Godbole
2010-06-30
In this article I trace the development of the human understanding of the "Heart of Matter" from early concepts of "elements" (or alternatively "Panchmahabhootas") to the current status of "quarks" and "leptons" as the fundamental constituents of matter, interacting together via exchange of the various force carrier particles called "gauge bosons" such as the photon, W/Z-boson etc. I would like to show how our understanding of the fundamental constituents of matter has gone hand in hand with our understanding of the fundamental forces in nature. I will also outline how the knowledge of particle physics at the "micro" scale of less than a Fermi(one millionth of a nanometer), enables us to offer explanations of Cosmological observations at the "macro" scale. Consequently these observations, may in turn, help us address some very fundamental questions of the Physics at the "Heart of the Matter".
D'Eramo, Francesco
2012-01-01
In this thesis, we build new Effective Field Theory tools to describe the propagation of energetic partons in hot and dense media, and we propose two new reactions for dark matter in the early universe. In the first part, ...
The X-ray Spectrum of SAX J1808.4-3658
W. A. Heindl; D. M. Smith
1998-08-07
We report on the X-ray spectrum of the 401 Hz X-ray pulsar and type I burst source SAX J1808.4-3658, during its 1998 April/May hard outburst. The observations were made with RXTE over a period of three weeks. The spectrum is well-described by a power law with photon index 1.86+/-0.01 that is exponentially cut off at high energies. Excess soft emission above the power law is present as well as a weak Fe-K line. This is the first truly simultaneous broad-band (2.5-250 keV) spectrum of a type I burst source in the hard state. The spectrum is consistent with other hard state burster spectra which cover either only the soft (1-20 keV) or hard (>20 keV) bands, or cover both, but not simultaneously. The cut-off power law resembles black hole candidates (BHCs) in their low states, observed with RXTE. We compare the SAX J1808.4-3658 spectrum to three BHCs and find that the power law is somewhat softer. This suggests that the photon index may provide a way to distinguish between low state emission from Galactic black holes and type I bursters.
Laura Baudis
2015-09-02
One of the major challenges of modern physics is to decipher the nature of dark matter. Astrophysical observations provide ample evidence for the existence of an invisible and dominant mass component in the observable universe, from the scales of galaxies up to the largest cosmological scales. The dark matter could be made of new, yet undiscovered elementary particles, with allowed masses and interaction strengths with normal matter spanning an enormous range. Axions, produced non-thermally in the early universe, and weakly interacting massive particles (WIMPs), which froze out of thermal equilibrium with a relic density matching the observations, represent two well-motivated, generic classes of dark matter candidates. Dark matter axions could be detected by exploiting their predicted coupling to two photons, where the highest sensitivity is reached by experiments using a microwave cavity permeated by a strong magnetic field. WIMPs could be directly observed via scatters off atomic nuclei in underground, ultra low-background detectors, or indirectly, via secondary radiation produced when they pair annihilate. They could also be generated at particle colliders such as the LHC, where associated particles produced in the same process are to be detected. After a brief motivation and an introduction to the phenomenology of particle dark matter detection, I will discuss the most promising experimental techniques to search for axions and WIMPs, addressing their current and future science reach, as well as their complementarity.
Maximizing available spectrum for cognitive radios
Mishra, Shridhar Mubaraq
2009-01-01
V. Saligrama, “Robust Energy Efficient Cooperative SpectrumV. Saligrama, “Robust Energy Efficient Cooperative Spectrumusing cooperative sensing to gather as much energy in the
Primordial perturbations in tachyonic power-law inflation
de Souza, Rudinei C
2013-01-01
In this work we determine the power spectrum of the gravitational potential of the primordial fluctuations for an inflationary model whose \\emph{inflaton} is a non-canonical scalar field of the tachyon-type. The respective background field equations for an inverse-square potential produce a power-law inflation, and it is explicitly shown that for such a potential the power spectrum tends to be scale-independent for highly accelerated regimes in the inflationary expansion.
Tsai, Yue-Lin Sming [National Center for Nuclear Research, Hoza 69, 00-681 Warsaw (Poland); Yuan, Qiang [Key Laboratory of Particle Astrophysics, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049, P.R.China (China); Huang, Xiaoyuan, E-mail: Sming.Tsai@fuw.edu.pl, E-mail: yuanq@ihep.ac.cn, E-mail: x_huang@bao.ac.cn [National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, P.R.China (China)
2013-03-01
Observation of ?-rays from dwarf galaxies is an effective way to search for particle dark matter. Using 4-year data of Fermi-LAT observations on a series of Milky Way satellites, we develop a general way to search for the signals from dark matter annihilation in such objects. Instead of giving prior information about the energy spectrum of dark matter annihilation, we bin the Fermi-LAT data into several energy bins and build a likelihood map in the ''energy bin - flux'' plane. The final likelihood of any spectrum can be easily derived through combining the likelihood of all the energy bins. It gives consistent result with that directly calculated using the Fermi Scientific Tool. This method is very efficient for the study of any specific dark matter models with ?-rays. We use the new likelihood map with Fermi-LAT 4 year data to fit the parameter space in three representative dark matter models: i) toy dark matter model, ii) effective dark matter operators, and iii) supersymmetric neutralino dark matter.
The Subatomic Particle Mass Spectrum
R. L. Oldershaw
2010-09-20
Representative members of the subatomic particle mass spectrum in the 100 MeV to 7,000 MeV range are retrodicted to a first approximation using the Kerr solution of General Relativity. The particle masses appear to form a restricted set of quantized values of a Kerr-based angular momentum-mass relation: m = (sqrt n)(M), where values of n are a set of discrete integers and M is a revised Planck mass. A fractal paradigm manifesting global discrete self-similarity is critical to a proper determination of M, which differs from the conventional Planck mass by roughly 19 orders of magnitude. This exceedingly simple and generic mass equation retrodicts the masses of a representative set of 27 well-known particles with an average relative error of 1.6%. A more rigorous mass formula, which includes the total spin angular momentum rule of Quantum Mechanics, the canonical spin values of the particles, and the dimensionless rotational parameter of the Kerr angular momentum-mass relation, is able to retrodict the masses of the 8 dominant baryons in the 900 MeV to 1700 MeV range at the 99.7% level, on average.
Stealth Dark Matter: Dark scalar baryons through the Higgs portal
Thomas Appelquist; Richard C. Brower; Michael I. Buchoff; George T. Fleming; Xiao-Yong Jin; Joe Kiskis; Graham D. Kribs; Ethan T. Neil; James C. Osborn; Claudio Rebbi; Enrico Rinaldi; David Schaich; Chris Schroeder; Sergey Syritsyn; Pavlos Vranas; Evan Weinberg; Oliver Witzel
2015-05-28
We present a new model of "Stealth Dark Matter": a composite baryonic scalar of an $SU(N_D)$ strongly-coupled theory with even $N_D \\geq 4$. All mass scales are technically natural, and dark matter stability is automatic without imposing an additional discrete or global symmetry. Constituent fermions transform in vector-like representations of the electroweak group that permit both electroweak-breaking and electroweak-preserving mass terms. This gives a tunable coupling of stealth dark matter to the Higgs boson independent of the dark matter mass itself. We specialize to $SU(4)$, and investigate the constraints on the model from dark meson decay, electroweak precision measurements, basic collider limits, and spin-independent direct detection scattering through Higgs exchange. We exploit our earlier lattice simulations that determined the composite spectrum as well as the effective Higgs coupling of stealth dark matter in order to place bounds from direct detection, excluding constituent fermions with dominantly electroweak-breaking masses. A lower bound on the dark baryon mass $m_B \\gtrsim 300$ GeV is obtained from the indirect requirement that the lightest dark meson not be observable at LEP II. We briefly survey some intriguing properties of stealth dark matter that are worthy of future study, including: collider studies of dark meson production and decay; indirect detection signals from annihilation; relic abundance estimates for both symmetric and asymmetric mechanisms; and direct detection through electromagnetic polarizability, a detailed study of which will appear in a companion paper.
Structure formation and CMBR anisotropy spectrum in the inflessence model
A. A. Sen; V. F. Cardone; S. Capozziello; A. Troisi
2006-07-25
The inflessence model has recently been proposed in an attempt to explain both early inflation and present day accelerated expansion within a single mechanism. The model has been successfully tested against the Hubble diagram of Type Ia Supernovae, the shift parameter, and the acoustic peak parameter. As a further mandatory test, we investigate here structure formation in the inflessence model determining the evolution of matter density contrast $\\delta \\equiv \\delta \\rho_M/\\rho_M$ in the linear regime. We compare the growth factor $D(a) \\equiv \\delta/a$ and the growth index $f(z) \\equiv d\\ln{\\delta}/d\\ln{a}$ to these same quantities for the successful concordance $\\Lambda$CDM model with a particular emphasis on the role of the inflessence parameters $(\\gamma, z_Q)$. We also evaluate the anisotropy spectrum of the cosmic microwave background radiation (CMBR) to check whether the inflessence model may be in agreement with the observations. We find that, for large values of $(\\gamma, z_Q)$, structure formation proceeds in a similar way to that in the $\\Lambda$CDM scenario, and it is also possible to nicely fit the CMBR spectrum.
Quasicrystals with discrete support and spectrum
Nir Lev; Alexander Olevskii
2015-09-08
We proved recently that a measure on R, whose support and spectrum are both uniformly discrete sets, must have a periodic structure. Here we show that this is not the case if the support and the spectrum are just discrete closed sets.
Not Available
1994-01-06
The Electric Power Annual presents a summary of electric utility statistics at national, regional and State levels. The objective of the publication is to provide industry decisionmakers, government policymakers, analysts and the general public with historical data that may be used in understanding US electricity markets. The Electric Power Annual is prepared by the Survey Management Division; Office of Coal, Nuclear, Electric and Alternate Fuels; Energy Information Administration (EIA); US Department of Energy. ``The US Electric Power Industry at a Glance`` section presents a profile of the electric power industry ownership and performance, and a review of key statistics for the year. Subsequent sections present data on generating capability, including proposed capability additions; net generation; fossil-fuel statistics; retail sales; revenue; financial statistics; environmental statistics; electric power transactions; demand-side management; and nonutility power producers. In addition, the appendices provide supplemental data on major disturbances and unusual occurrences in US electricity power systems. Each section contains related text and tables and refers the reader to the appropriate publication that contains more detailed data on the subject matter. Monetary values in this publication are expressed in nominal terms.
Non-cooperative Spectrum Access The Dedicated vs. Free Spectrum Choice
Zussman, Gil
Non-cooperative Spectrum Access The Dedicated vs. Free Spectrum Choice Krishna Jagannathan MIT 77 consider a dynamic spectrum access system in which Secondary Users (SUs) choose to either acquire dedicated dedicated bands to SUs. Finally, we extend the scope to a scenario with multi- ple PUs, show that the band
Moments of $?$ meson spectral functions in vacuum and nuclear matter
Philipp Gubler; Wolfram Weise
2015-07-14
Moments of the $\\phi$ meson spectral function in vacuum and in nuclear matter are analyzed, combining a model based on chiral SU(3) effective field theory (with kaonic degrees of freedom) and finite-energy QCD sum rules. For the vacuum we show that the spectral density is strongly constrained by a recent accurate measurement of the $e^+ e^- \\to K^+ K^-$ cross section. In nuclear matter the $\\phi$ spectrum is modified by interactions of the decay kaons with the surrounding nuclear medium, leading to a significant broadening and an asymmetric deformation of the $\\phi$ meson peak. We demonstrate that both in vacuum and nuclear matter, the first two moments of the spectral function are compatible with finite-energy QCD sum rules. A brief discussion of the next-higher spectral moment involving strange four-quark condensates is also presented.
NREL Spectrum of Clean Energy Innovation (Brochure)
Not Available
2011-09-01
This brochure describes the NREL Spectrum of Clean Energy Innovation, which includes analysis and decision support, fundamental science, market relevant research, systems integration, testing and validation, commercialization and deployment. Through deep technical expertise and an unmatched breadth of capabilities, the National Renewable Energy Laboratory (NREL) leads an integrated approach across the spectrum of renewable energy innovation. From scientific discovery to accelerating market deployment, NREL works in partnership with private industry to drive the transformation of our nation's energy systems. NREL integrates the entire spectrum of innovation, including fundamental science, market relevant research, systems integration, testing and validation, commercialization, and deployment. Our world-class analysis and decision support informs every point on the spectrum. The innovation process at NREL is inter-dependent and iterative. Many scientific breakthroughs begin in our own laboratories, but new ideas and technologies may come to NREL at any point along the innovation spectrum to be validated and refined for commercial use.
The effect of stochastic re-acceleration on the energy spectrum of shock-accelerated protons
Afanasiev, Alexandr; Vainio, Rami [Department of Physics, University of Helsinki, P.O. Box 64, Helsinki FI-00014 (Finland); Kocharov, Leon [Sodankylä Geophysical Observatory (Oulu Unit), University of Oulu, Oulu FI-90014 (Finland)
2014-07-20
The energy spectra of particles in gradual solar energetic particle (SEP) events do not always have a power-law form attributed to the diffusive shock acceleration mechanism. In particular, the observed spectra in major SEP events can take the form of a broken (double) power law. In this paper, we study the effect of a process that can modify the power-law spectral form produced by the diffusive shock acceleration: the stochastic re-acceleration of energetic protons by enhanced Alfvénic turbulence in the downstream region of a shock wave. There are arguments suggesting that this process can be important when the shock propagates in the corona. We consider a coronal magnetic loop traversed by a shock and perform Monte Carlo simulations of interactions of shock-accelerated protons with Alfvén waves in the loop. The wave-particle interactions are treated self-consistently, so the finiteness of the available turbulent energy is taken into account. The initial energy spectrum of particles is taken to be a power law. The simulations reveal that the stochastic re-acceleration leads either to the formation of a spectrum that is described in a wide energy range by a power law (although the resulting power-law index is different from the initial one) or to a broken power-law spectrum. The resulting spectral form is determined by the ratio of the energy density of shock-accelerated protons to the wave energy density in the shock's downstream region.
I. Stern
2014-03-21
Nearly all astrophysical and cosmological data point convincingly to a large component of cold dark matter in the Universe. The axion particle, first theorized as a solution to the strong charge-parity problem of quantum chromodynamics, has been established as a prominent CDM candidate. Cosmic observation and particle physics experiments have bracketed the unknown mass of the axion between approximately a $\\mu$eV and a meV. The Axion Dark Matter eXperiement (ADMX) has successfully completed searches between 1.9 and 3.7 $\\mu$eV down to the KSVZ photon-coupling limit. ADMX and the Axion Dark Matter eXperiement High-Frequency (ADMX-HF) will search for axions at weaker coupling and/or higher frequencies within the next few years. Status of the experiments, current research and development, and projected mass-coupling exclusion limits are presented.
Stern, I
2014-01-01
Nearly all astrophysical and cosmological data point convincingly to a large component of cold dark matter in the Universe. The axion particle, first theorized as a solution to the strong charge-parity problem of quantum chromodynamics, has been established as a prominent CDM candidate. Cosmic observation and particle physics experiments have bracketed the unknown mass of the axion between approximately a $\\mu$eV and a meV. The Axion Dark Matter eXperiement (ADMX) has successfully completed searches between 1.9 and 3.7 $\\mu$eV down to the KSVZ photon-coupling limit. ADMX and the Axion Dark Matter eXperiement High-Frequency (ADMX-HF) will search for axions at weaker coupling and/or higher frequencies within the next few years. Status of the experiments, current research and development, and projected mass-coupling exclusion limits are presented.
Thermodynamics of clusterized matter
Ad. R. Raduta; F. Gulminelli
2009-08-26
Thermodynamics of clusterized matter is studied in the framework of statistical models with non-interacting cluster degrees of freedom. At variance with the analytical Fisher model, exact Metropolis simulation results indicate that the transition from homogeneous to clusterized matter lies along the $\\rho=\\rho_0$ axis at all temperatures and the limiting point of the phase diagram is not a critical point even if the surface energy vanishes at this point. Sensitivity of the inferred phase diagram to the employed statistical framework in the case of finite systems is discussed by considering the grand-canonical and constant-pressure canonical ensembles. A Wigner-Seitz formalism in which the fragment charge is neutralized by an uniform electron distribution allows to build the phase diagram of neutron star matter.
Fabbrichesi, Marco
2015-01-01
We show how the Higgs boson mass is protected from the potentially large corrections due to the introduction of minimal dark matter if the new physics sector is made supersymmetric. The fermionic dark matter candidate (a 5-plet of $SU(2)_L$) is accompanied by a scalar state. The weak gauge sector is made supersymmetric and the Higgs boson is embedded in a supersymmetric multiplet. The remaining standard model states are non-supersymmetric. Non vanishing corrections to the Higgs boson mass only appear at three-loop level and the model is natural for dark matter masses up to 15 TeV--a value larger than the one required by the cosmological relic density. The construction presented stands as an example of a general approach to naturalness that solves the little hierarchy problem which arises when new physics is added beyond the standard model at an energy scale around 10 TeV.
I. Stern
2015-11-17
Nearly all astrophysical and cosmological data point convincingly to a large component of cold dark matter in the Universe. The axion particle, first theorized as a solution to the strong charge-parity problem of quantum chromodynamics, has been established as a prominent CDM candidate. Cosmic observation and particle physics experiments have bracketed the unknown mass of the axion between approximately a $\\mu$eV and a meV. The Axion Dark Matter eXperiement (ADMX) has successfully completed searches between 1.9 and 3.7 $\\mu$eV down to the KSVZ photon-coupling limit. ADMX and the Axion Dark Matter eXperiement High-Frequency (ADMX-HF) will search for axions at weaker coupling and/or higher frequencies within the next few years. Status of the experiments, current research and development, and projected mass-coupling exclusion limits are presented.
C. O. Dorso; P. A. Giménez Molinelli; J. I. Nichols; J. A. López
2013-05-09
The behavior of nuclear matter is studied at low densities and temperatures using classical molecular dynamics with three different sets of potentials with different compressibility. Nuclear matter is found to arrange in crystalline structures around the saturation density and in non-homogeneous (i.e. pasta-like) structures at lower densities. Similar results were obtained with a simple Lennard-Jones potential. Finite size effects are analysed and the existence of the non-homogeneous structures is shown to be inherent to the use of periodic boundary conditions and the finitude of the system. For large enough systems the non-homogeneous structures are limited to one sphere, one rod or one slab per simulation cell, which are shown to be minimal surface structures under cubic periodic boundary conditions at the corresponding volume fraction. The relevance of these findings to the simulations of neutron star and supernovae matter is discussed.
Asymptotically Safe Dark Matter
Francesco Sannino; Ian M. Shoemaker
2015-08-05
We introduce a new paradigm for dark matter (DM) interactions in which the interaction strength is asymptotically safe. In models of this type, the coupling strength is small at low energies but increases at higher energies, and asymptotically approaches a finite constant value. The resulting phenomenology of this "asymptotically safe DM" is quite distinct. One interesting effect of this is to partially offset the low-energy constraints from direct detection experiments without affecting thermal freeze-out processes which occur at higher energies. High-energy collider and indirect annihilation searches are the primary ways to constrain or discover asymptotically safe dark matter.
Francesco Sannino; Ian M. Shoemaker
2015-07-29
We introduce a new paradigm for dark matter (DM) interactions in which the interaction strength is asymptotically safe. In models of this type, the coupling strength is small at low energies but increases at higher energies, and asymptotically approaches a finite constant value. The resulting phenomenology of this "safe DM" is quite distinct. One interesting effect of this is to partially offset the low-energy constraints from direct detection experiments without affecting thermal freeze-out processes which occur at higher energies. High-energy collider and indirect annihilation searches are the primary ways to constrain or discover safe dark matter.
Closed loop adaptive control of spectrum-producing step using neural networks
Fu, C.Y.
1998-11-24
Characteristics of the plasma in a plasma-based manufacturing process step are monitored directly and in real time by observing the spectrum which it produces. An artificial neural network analyzes the plasma spectrum and generates control signals to control one or more of the process input parameters in response to any deviation of the spectrum beyond a narrow range. In an embodiment, a plasma reaction chamber forms a plasma in response to input parameters such as gas flow, pressure and power. The chamber includes a window through which the electromagnetic spectrum produced by a plasma in the chamber, just above the subject surface, may be viewed. The spectrum is conducted to an optical spectrometer which measures the intensity of the incoming optical spectrum at different wavelengths. The output of optical spectrometer is provided to an analyzer which produces a plurality of error signals, each indicating whether a respective one of the input parameters to the chamber is to be increased or decreased. The microcontroller provides signals to control respective controls, but these lines are intercepted and first added to the error signals, before being provided to the controls for the chamber. The analyzer can include a neural network and an optional spectrum preprocessor to reduce background noise, as well as a comparator which compares the parameter values predicted by the neural network with a set of desired values provided by the microcontroller. 7 figs.
Closed loop adaptive control of spectrum-producing step using neural networks
Fu, Chi Yung (San Francisco, CA)
1998-01-01
Characteristics of the plasma in a plasma-based manufacturing process step are monitored directly and in real time by observing the spectrum which it produces. An artificial neural network analyzes the plasma spectrum and generates control signals to control one or more of the process input parameters in response to any deviation of the spectrum beyond a narrow range. In an embodiment, a plasma reaction chamber forms a plasma in response to input parameters such as gas flow, pressure and power. The chamber includes a window through which the electromagnetic spectrum produced by a plasma in the chamber, just above the subject surface, may be viewed. The spectrum is conducted to an optical spectrometer which measures the intensity of the incoming optical spectrum at different wavelengths. The output of optical spectrometer is provided to an analyzer which produces a plurality of error signals, each indicating whether a respective one of the input parameters to the chamber is to be increased or decreased. The microcontroller provides signals to control respective controls, but these lines are intercepted and first added to the error signals, before being provided to the controls for the chamber. The analyzer can include a neural network and an optional spectrum preprocessor to reduce background noise, as well as a comparator which compares the parameter values predicted by the neural network with a set of desired values provided by the microcontroller.
Singing the Power Winter 2013-14
Virginia Tech
would be standard equipment in a time machine traversing the generations. Making power palatable is what Professor and the director of the Center for Power Electronics Systems, the modules are perfect examples has to be smooth and consistent for a machine to use, no matter the machine's size or energy needs
Climate Change, Nuclear Power and Nuclear
Climate Change, Nuclear Power and Nuclear Proliferation: Magnitude Matters Rob Goldston MIT IAP biomass wind hydro coal CCS coal nat gas CCS nat gas nuclear Gen IV nuclear Gen III nuclear Gen II 5-1 Electricity Generation: CCS and Nuclear Power Technology Options Available Global Electricity Generation WRE
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Perovskite Power 1663 Los Alamos science and technology magazine Latest Issue:October 2015 past issues All Issues submit Perovskite Power A breakthrough in the production of...
Investigation of Direct Injection Vehicle Particulate Matter...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Direct Injection Vehicle Particulate Matter Emissions Investigation of Direct Injection Vehicle Particulate Matter Emissions This study focuses primarily on particulate matter mass...
Asymmetric condensed dark matter
Aguirre, Anthony
2015-01-01
We explore the viability of a boson dark matter candidate with an asymmetry between the number densities of particles and antiparticles. A simple thermal field theory analysis confirms that, under certain general conditions, this component would develop a Bose-Einstein condensate in the early universe that, for appropriate model parameters, could survive the ensuing cosmological evolution until now. The condensation of a dark matter component in equilibrium with the thermal plasma is a relativistic process, hence the amount of matter dictated by the charge asymmetry is complemented by a hot relic density frozen out at the time of decoupling. Contrary to the case of ordinary WIMPs, dark matter particles in a condensate can be very light, $10^{-22}\\,{\\rm eV} \\lesssim m \\lesssim 10^2\\,{\\rm eV}$; the lower limit arises from constraints on small-scale structure formation, while the upper bound ensures that the density from thermal relics is not too large. Big-Bang nucleosynthesis constrains the temperature of deco...
C. D. Froggatt; H. B. Nielsen
2015-05-10
It is suggested that the Tunguska event in June 1908 cm-large was due to a cm-large ball of a condensate of bound states of 6 top and 6 anti-top quarks containing highly compressed ordinary matter. Such balls are supposed to make up the dark matter as we earlier proposed. The expected rate of impact of this kind of dark matter ball with the earth seems to crudely match a time scale of 200 years between the impacts. The main explosion of the Tunguska event is explained in our picture as material coming out from deep within the earth, where it has been heated and compressed by the ball penetrating to a depth of several thousand km. Thus the effect has some similarity with volcanic activity as suggested by Kundt. We discuss the possible identification of kimberlite pipes with earlier Tunguska-like events. A discussion of how the dark matter balls may have formed in the early universe is also given.
2002-03-01
Quarterly newsletter from DOE's Industrial Technologies Program to promote the use of energy-efficient industrial systems. The focus of the Spring 2002 Issue of Energy Matters focuses on premium energy efficiency systems, with articles on new gas technologies, steam efficiency, the Augusta Newsprint Showcase, and more.
2002-09-01
Quarterly newsletter from DOE's Industrial Technologies Program to promote the use of energy-efficient industrial systems. This issue focus of this edition of the Energy Matters Newsletter is on energy and environmental issues. Read more about compressed air's role in productivity, making good motor decisions, and more.
Subject Matters Introduction The AS and A Level subject choices you make when in Year 11 (or assessing applicants at the University of Cambridge, we consider not only the individual A Level subjects taken but also the combination of these. We generally prefer applicants to have taken certain subjects
Rogers, John A.
See Also: Matter & Energy Solar Energy· Electronics· Materials Science· Earth & Climate Energy at the University of Illinois, the future of solar energy just got brighter. Although silicon is the industry Electronics Over 1.2 Million Electronics Parts, Components and Equipment. www.AlliedElec.com solar energy
Laura Baudis
2005-11-29
More than 90% of matter in the Universe could be composed of heavy particles, which were non-relativistic, or 'cold', when they froze-out from the primordial soup. I will review current searches for these hypothetical particles, both via interactions with nuclei in deep underground detectors, and via the observation of their annihilation products in the Sun, galactic halo and galactic center.
The frequency spectrum of the Casimir effect
Lang, Andrew S.I.D. [Computer Science and Mathematics Department, Oral Roberts University, Tulsa, Oklahoma 74171 (United States)
2005-10-01
The frequency spectrum of the Casimir effect between parallel plates is studied. Calculations are performed for both the massless scalar field and the electromagnetic field cases, first using a spectral weight function, and then via the Fourier transform of the renormalized expectation of the Casimir energy-momentum operator. The Casimir force is calculated using the spectrum for two plates which are perfectly transparent in a frequency band. The result of this calculation suggests a way to detect the frequency spectrum of the Casimir effect.
Energy Matters in Washington State Page 1 Energy Matters
Collins, Gary S.
Energy Matters in Washington State Page 1 Energy Matters in Washington State June 2008 Updated November 2009 Updated and Revised October 2013 Grand Coulee Dam #12;Energy Matters in Washington State Page 2 Copyright © 2013 Washington State University Energy Program. 905 Plum Street SE, P.O. Box 43169
Cosmic Ray Protons Illuminate Dark Matter Axions
H. Tam; Q. Yang
2011-08-16
Cosmic ray protons propagating in a spatially-homogeneous but time-dependent field of axions or axion-like particles (ALPs) emit photons in a way that is reminiscent of Cherenkov radiation by charged particles in a preferred background. We compute the emission rate and energy spectrum of the photons, and discuss the possibility of their detection using the Square Kilometre Array which is currently under construction. In the case of a non-detection, constraints can be placed on the parameter space of ALPs whose mass lie between $10^{-7}$eV and $10^{-5}$ eV under the assumption that they are the primary constituent of dark matter.
ULTRA HIGH ENERGY COSMIC RAY SPECTRUM Baltrusaitis, R.M., Cady7
. The differential energy spectrum above 0.1 EeV is well fitted by a power law with slope 2.94 ± 0.02. Some evidence 0.1 EeV were detected in 1278 hours of live tune. 2. Energy and Spectral Calculation. The energy Gaussian and unconstrained (3 free parameters) Gaisser-Hillas2 curves. These curves are integrated
Orrell, John
2013-11-20
More than 25 years ago, PNNL scientists began the first underground measurements searching for dark matter using specialized radiation detector technology. Dark matter is yet to be discovered says Physicist John L. Orrell.
Orrell, John
2014-07-24
More than 25 years ago, PNNL scientists began the first underground measurements searching for dark matter using specialized radiation detector technology. Dark matter is yet to be discovered says Physicist John L. Orrell.
Soft Matter Perspective on Protein Crystal Assembly
Diana Fusco; Patrick Charbonneau
2015-07-10
Crystallography may be the gold standard of protein structure determination, but obtaining the necessary high-quality crystals is also in some ways akin to prospecting for the precious metal. The tools and models developed in soft matter physics to understand colloidal assembly offer some insights into the problem of crystallizing proteins. This topical review describes the various analogies that have been made between proteins and colloids in that context. We highlight the explanatory power of patchy particle models, but also the challenges of providing guidance for crystallizing specific proteins. We conclude with a presentation of possible future research directions. This article is intended for soft matter scientists interested in protein crystallization as a self-assembly problem, and as an introduction to the pertinent physics literature for protein scientists more generally.
Decision Analysis of Dynamic Spectrum Access Rules
Juan D. Deaton; Luiz A. DaSilva; Christian Wernz
2011-12-01
A current trend in spectrum regulation is to incorporate spectrum sharing through the design of spectrum access rules that support Dynamic Spectrum Access (DSA). This paper develops a decision-theoretic framework for regulators to assess the impacts of different decision rules on both primary and secondary operators. We analyze access rules based on sensing and exclusion areas, which in practice can be enforced through geolocation databases. Our results show that receiver-only sensing provides insufficient protection for primary and co-existing secondary users and overall low social welfare. On the other hand, using sensing information between the transmitter and receiver of a communication link, provides dramatic increases in system performance. The performance of using these link end points is relatively close to that of using many cooperative sensing nodes associated to the same access point and large link exclusion areas. These results are useful to regulators and network developers in understanding in developing rules for future DSA regulation.
The scalar bi-spectrum in the Starobinsky model: the equilateral case
Martin, Jérôme [Institut d'Astrophysique de Paris, UMR7095-CNRS, Université Pierre et Marie Curie, 98bis boulevard Arago, 75014 Paris (France); Sriramkumar, L., E-mail: jmartin@iap.fr, E-mail: sriram@physics.iitm.ac.in [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211019 (India)
2012-01-01
While a featureless, nearly scale invariant, primordial scalar power spectrum fits the most recent Cosmic Microwave Background (CMB) data rather well, certain features in the spectrum are known to lead to a better fit to the data (although, the statistical significance of such results remains an open issue). In the inflationary scenario, one or more periods of deviations from slow roll are necessary in order to generate features in the scalar perturbation spectrum. Over the last couple of years, it has been recognized that such deviations from slow roll inflation can also result in reasonably large non-Gaussianities. The Starobinsky model involves the canonical scalar field and consists of a linear inflaton potential with a sudden change in the slope. The change in the slope causes a brief period of departure from slow roll which, in turn, results in a sharp rise in power, along with a burst of oscillations in the scalar spectrum for modes that leave the Hubble radius just before and during the period of fast roll. The hallmark of the Starobinsky model is that it allows the scalar power spectrum to be evaluated analytically in terms of the three parameters that describe the model, viz. the two slopes that describe the potential on either side of the discontinuity and the Hubble scale at the time when the field crosses the discontinuity. In this work, we evaluate the bi-spectrum of the scalar perturbations in the Starobinsky model in the equilateral limit. Remarkably, we find that, just as the power spectrum, all the different contributions to the the bi-spectrum too can be evaluated completely analytically and expressed in terms of the three paramaters that describe the model. We show that the quantity f{sub NL}, which characterizes the extent of non-Gaussianity, can be expressed purely in terms of the ratio of the two slopes on either side of the discontinuity in the potential. Further, we find that, for certain values of the parameters, f{sub NL} in the Starobinsky model can be as large as the mean value that has been arrived at from the analysis of the recent CMB data. We also demonstrate that the usual hierarchy of contributions to the bi-spectrum can be altered for certain values of the parameters. Altogether, we find that the Starobinsky model represents a unique scenario wherein, even when the slow roll conditions are violated, the background, the perturbations as well as the corresponding two and three point correlation functions can be evaluated completely analytically. As a consequence, the Starobinsky model can also be used to calibrate numerical codes aimed at computing the non-Gaussianities.
Optimal Power Masking in Soft Frequency Reuse based
Gross, James
from the power radiated by the base station of neighboring cells in their communication band-carrier the base stations are restricted to a certain power bound. All these approaches to mitigating CCI can the fraction of the maximum transmit power that the base station may use depending at the part of the spectrum
arXiv:astro-ph/0610865v130Oct2006 Power Laws and the Cosmic Ray Energy
arXiv:astro-ph/0610865v130Oct2006 Power Laws and the Cosmic Ray Energy Spectrum J. D. Hague a,1 B and preliminary Auger Cosmic Ray Energy spectra in an attempt to find deviation from a pure power-law. The first spectrum suggests deviation from a power-law. However, potentially large systematics on the relative energy
Nemanja Kaloper; Antonio Padilla
2009-10-07
A sizable fraction of the total energy density of the universe may be in heavy particles with a net dark $U(1)'$ charge comparable to its mass. When the charges have the same sign the cancellation between their gravitational and gauge forces may lead to a mismatch between different measures of masses in the universe. Measuring galactic masses by orbits of normal matter, such as galaxy rotation curves or lensing, will give the total mass, while the flows of dark matter agglomerates may yield smaller values if the gauge repulsion is not accounted for. If distant galaxies which house light beacons like SNe Ia contain such dark particles, the observations of their cosmic recession may mistake the weaker forces for an extra `antigravity', and infer an effective dark energy equation of state smaller than the real one. In some cases, including that of a cosmological constant, these effects can mimic $wdark energy, or superhorizon effects.
Rigid particulate matter sensor
Hall, Matthew (Austin, TX)
2011-02-22
A sensor to detect particulate matter. The sensor includes a first rigid tube, a second rigid tube, a detection surface electrode, and a bias surface electrode. The second rigid tube is mounted substantially parallel to the first rigid tube. The detection surface electrode is disposed on an outer surface of the first rigid tube. The detection surface electrode is disposed to face the second rigid tube. The bias surface electrode is disposed on an outer surface of the second rigid tube. The bias surface electrode is disposed to face the detection surface electrode on the first rigid tube. An air gap exists between the detection surface electrode and the bias surface electrode to allow particulate matter within an exhaust stream to flow between the detection and bias surface electrodes.
Discovering Inelastic Thermal-Relic Dark Matter at Colliders
Izaguirre, Eder; Shuve, Brian
2015-01-01
Dark Matter particles with inelastic interactions are ubiquitous in extensions of the Standard Model, yet remain challenging to fully probe with existing strategies. We propose a series of powerful searches at hadron and lepton colliders that are sensitive to inelastic dark matter dynamics. In representative models, we find that the LHC and BaBar could offer strong sensitivity to the thermal-relic dark matter parameter space for dark matter masses between ~100 MeV-100 GeV and fractional mass-splittings above the percent level; future searches at Belle II with a dedicated monophoton trigger could also offer sensitivity to thermal-relic scenarios with masses below a few GeV. Thermal scenarios with either larger masses or splittings are largely ruled out; lower masses remain viable yet may be accessible with other search strategies.
Benjamin D. Wandelt; Romeel Dave; Glennys R. Farrar; Patrick C. McGuire; David N. Spergel; Paul J. Steinhardt
2000-06-28
Spergel and Steinhardt have recently proposed the concept of dark matter with strong self-interactions as a means to address numerous discrepancies between observations of dark matter halos on subgalactic scales and the predictions of the standard collisionless dark matter picture. We review the motivations for this scenario and discuss some recent, successful numerical tests. We also discuss the possibility that the dark matter interacts strongly with ordinary baryonic matter, as well as with itself. We present a new analysis of the experimental constraints and re-evaluate the allowed range of cross-section and mass.
Measurement Guide and Programming PSA and ESA Series Spectrum Analyzers
Anlage, Steven
Measurement Guide and Programming Examples PSA and ESA Series Spectrum Analyzers This manual information about Agilent Technologies PSA and ESA spectrum analyzers, including firmware upgrades
Baryon Spectrum from Superconformal Quantum Mechanics and its...
Office of Scientific and Technical Information (OSTI)
Baryon Spectrum from Superconformal Quantum Mechanics and its Light-Front Holographic Embedding Citation Details In-Document Search Title: Baryon Spectrum from Superconformal...
Baryon Spectrum from Superconformal Quantum Mechanics and its...
Office of Scientific and Technical Information (OSTI)
Journal Article: Baryon Spectrum from Superconformal Quantum Mechanics and its Light-Front Holographic Embedding Citation Details In-Document Search Title: Baryon Spectrum from...
Developments in Chiral effective Field Theory for Nuclear Matter
J. A. Oller
2012-06-12
We review on a chiral power counting scheme for in-medium chiral perturbation theory with nucleons and pions as degrees of freedom \\cite{ref}. It allows for a systematic expansion taking into account local as well as pion-mediated inter-nucleon interactions. Based on this power counting, one can identify classes of non-perturbative diagrams that require a resummation. We then calculate the nuclear matter energy density for the symmetric and purely neutron matter cases up-to-and-including next-to-leading order (NLO), in good agreement with sophisticated many-body calculations. Next, the neutron matter equation of state is applied to calculate the upper limit for neutron stars, with an upper bound around 2.3 solar masses, large enough to accommodate the most massive neutron star observed until now. We also apply our equation state to constraint $G_N$ in exceptionally large gravitational fields.
Thomas Hambye
2010-03-16
We show that dark matter could be made of massive gauge bosons whose stability doesn't require to impose by hand any discrete or global symmetry. Stability of gauge bosons can be guaranteed by the custodial symmetry associated to the gauge symmetry and particle content of the model. The particle content we consider to this end is based on a hidden sector made of a vector multiplet associated to a non-abelian gauge group and of a scalar multiplet charged under this gauge group. The hidden sector interacts with the Standard Model particles through the Higgs portal quartic scalar interaction in such a way that the gauge bosons behave as thermal WIMPS. This can lead easily to the observed dark matter relic density in agreement with the other various constraints, and can be tested experimentally in a large fraction of the parameter space. In this model the dark matter direct detection rate and the annihilation cross section can decouple if the Higgs portal interaction is weak.
Todorov, Alex
When physical similarity matters: Mechanisms underlying affective learning generalization instructions to disregard physical similarity Learning generalization is a powerful and relatively automatic). The findings of the experiments suggest that learning generalization based on facial physical similarity
Distinct optical properties of relativistically degenerate matter
Akbari-Moghanjoughi, M.
2014-06-15
In this paper, we use the collisional quantum magnetohydrodynamic (CQMHD) model to derive the transverse dielectric function of a relativistically degenerate electron fluid and investigate various optical parameters, such as the complex refractive index, the reflection and absorption coefficients, the skin-depth and optical conductivity. In this model we take into accounts effects of many parameters such as the atomic-number of the constituent ions, the electron exchange, electron diffraction effect and the electron-ion collisions. Study of the optical parameters in the solid-density, the warm-dense-matter, the big-planetary core, and the compact star number-density regimes reveals that there are distinct differences between optical characteristics of the latter and the former cases due to the fundamental effects of the relativistic degeneracy and other quantum mechanisms. It is found that in the relativistic degeneracy plasma regime, such as found in white-dwarfs and neutron star crusts, matter possess a much sharper and well-defined step-like reflection edge beyond the x-ray electromagnetic spectrum, including some part of gamma-ray frequencies. It is also remarked that the magnetic field intensity only significantly affects the plasma reflectivity in the lower number-density regime, rather than the high density limit. Current investigation confirms the profound effect of relativistic degeneracy on optical characteristics of matter and can provide an important plasma diagnostic tool for studying the physical processes within the wide scope of quantum plasma regimes be it the solid-density, inertial-confined, or astrophysical compact stars.
Decaying Dark Matter in the Supersymmetric Standard Model with Freeze-in and Seesaw mechanims
Zhaofeng Kang; Tianjun Li
2010-08-10
Inspired by the decaying dark matter (DM) which can explain cosmic ray anomalies naturally, we consider the supersymmetric Standard Model with three right-handed neutrinos (RHNs) and R-parity, and introduce a TeV-scale DM sector with two fields \\phi_{1,2} and a $Z_3$ discrete symmetry. The DM sector only interacts with the RHNs via a very heavy field exchange and then we can explain the cosmic ray anomalies. With the second right-handed neutrino N_2 dominant seesaw mechanism at the low scale around 10^4 GeV, we show that \\phi_{1,2} can obtain the vacuum expectation values around the TeV scale, and then the lightest state from \\phi_{1,2} is the decay DM with lifetime around \\sim 10^{26}s. In particular, the DM very long lifetime is related to the tiny neutrino masses, and the dominant DM decay channels to \\mu and \\tau are related to the approximate \\mu-\\tau symmetry. Furthermore, the correct DM relic density can be obtained via the freeze-in mechanism, the small-scale problem for power spectrum can be solved due to the decays of the R-parity odd meta-stable states in the DM sector, and the baryon asymmetry can be generated via the soft leptogensis.
Decaying Dark Matter in the Supersymmetric Standard Model with Freeze-in and Seesaw mechanims
Kang, Zhaofeng
2010-01-01
Inspired by the decaying dark matter (DM) which can explain cosmic ray anomalies naturally, we consider the supersymmetric Standard Model with three right-handed neutrinos (RHNs) and R-parity, and introduce a TeV-scale DM sector with two fields \\phi_{1,2} and a $Z_3$ discrete symmetry. The DM sector only interacts with the RHNs via a very heavy field exchange and then we can explain the cosmic ray anomalies. With the second right-handed neutrino N_2 dominant seesaw mechanism at the low scale around 10^4 GeV, we show that \\phi_{1,2} can obtain the vacuum expectation values around the TeV scale, and then the lightest state from \\phi_{1,2} is the decay DM with lifetime around \\sim 10^{26}s. In particular, the DM very long lifetime is related to the tiny neutrino masses, and the dominant DM decay channels to \\mu and \\tau are related to the approximate \\mu-\\tau symmetry. Furthermore, the correct DM relic density can be obtained via the freeze-in mechanism, the small-scale problem for power spectrum can be solved d...
Weak Lensing: Dark Matter, Dark Energy
Jain, Bhuvnesh (University of Pennsylvania) [University of Pennsylvania
2006-02-27
The light rays from distant galaxies are deflected by massive structures along the line of sight, causing the galaxy images to be distorted. Measurements of these distortions, known as weak lensing, provide a way of measuring the distribution of dark matter as well as the spatial geometry of the universe. I will describe the ideas underlying this approach to cosmology. With planned large imaging surveys, weak lensing is a powerful probe of dark energy. I will discuss the observational challenges ahead and recent progress in developing multiple, complementary approaches to lensing measurements.
Hamburger, Peter
Guidelines for Documentation of Autism Spectrum Disorders Autism Spectrum Disorders (ASD) includes autism, Asperger syndrome, and pervasive developmental disorder. ASDs are characterized generally
BINGO: a code for the efficient computation of the scalar bi-spectrum
Hazra, Dhiraj Kumar [Harish-Chandra Research Institute, Chhatnag Road, Jhunsi, Allahabad 211019 (India); Sriramkumar, L. [Department of Physics, Indian Institute of Technology Madras, Chennai 600036 (India); Martin, Jérôme, E-mail: dhiraj@apctp.org, E-mail: sriram@physics.iitm.ac.in, E-mail: jmartin@iap.fr [Institut d'Astrophysique de Paris, UMR7095-CNRS, Université Pierre et Marie Curie, 98bis boulevard Arago, 75014 Paris (France)
2013-05-01
We present a new and accurate Fortran code, the BI-spectra and Non-Gaussianity Operator (BINGO), for the efficient numerical computation of the scalar bi-spectrum and the non-Gaussianity parameter f{sub NL} in single field inflationary models involving the canonical scalar field. The code can calculate all the different contributions to the bi-spectrum and the parameter f{sub NL} for an arbitrary triangular configuration of the wavevectors. Focusing firstly on the equilateral limit, we illustrate the accuracy of BINGO by comparing the results from the code with the spectral dependence of the bi-spectrum expected in power law inflation. Then, considering an arbitrary triangular configuration, we contrast the numerical results with the analytical expression available in the slow roll limit, for, say, the case of the conventional quadratic potential. Considering a non-trivial scenario involving deviations from slow roll, we compare the results from the code with the analytical results that have recently been obtained in the case of the Starobinsky model in the equilateral limit. As an immediate application, we utilize BINGO to examine of the power of the non-Gaussianity parameter f{sub NL} to discriminate between various inflationary models that admit departures from slow roll and lead to similar features in the scalar power spectrum. We close with a summary and discussion on the implications of the results we obtain.
Exact Mapping between Tensor and Most General Scalar Power Spectra
Jose Beltran Jimenez; Marcello Musso; Christophe Ringeval
2013-09-03
We prove an exact relation between the tensor and the scalar primordial power spectra generated during inflation. Such a mapping considerably simplifies the derivation of any power spectra as they can be obtained from the study of the tensor modes only, which are much easier to solve. As an illustration, starting from the second order slow-roll tensor power spectrum, we derive in a few lines the next-to-next-to-leading order power spectrum of the comoving curvature perturbation in generalized single field inflation with a varying speed of sound.
Annihilation vs. decay: constraining dark matter properties from a gamma-ray detection
Palomares-Ruiz, Sergio [Centro de Física Teórica de Partículas, Instituto Superior Técnico, Av. Rovisco Pais 1, 1049-001 Lisboa (Portugal); Siegal-Gaskins, Jennifer M., E-mail: sergio.palomares.ruiz@ist.utl.pt, E-mail: jsg@mps.ohio-state.edu [Center for Cosmology and AstroParticle Physics, The Ohio State University, 191 W. Woodruff Ave., Columbus OH 43210 (United States)
2010-07-01
Most proposed dark matter candidates are stable and are produced thermally in the early Universe. However, there is also the possibility of unstable (but long-lived) dark matter, produced thermally or otherwise. We propose a strategy to distinguish between dark matter annihilation and/or decay in the case that a clear signal is detected in gamma-ray observations of Milky Way dwarf spheroidal galaxies with gamma-ray experiments. The sole measurement of the energy spectrum of an indirect signal would render the discrimination between these cases impossible. We show that by examining the dependence of the intensity and energy spectrum on the angular distribution of the emission, the origin could be identified as decay, annihilation, or both. In addition, once the type of signal is established, we show how these measurements could help to extract information about the dark matter properties, including mass, annihilation cross section, lifetime, dominant annihilation and decay channels, and the presence of substructure. Although an application of the approach presented here would likely be feasible with current experiments only for very optimistic dark matter scenarios, the improved sensitivity of upcoming experiments could enable this technique to be used to study a wider range of dark matter models.
The QCD spectrum with three quark flavors
Claude Bernard; Tom Burch; Thomas A. DeGrand; Saumen Datta; Carleton DeTar; Steven Gottlieb; Urs M. Heller; Kostas Orginos; Robert Sugar; Doug Toussaint
2001-05-29
We present results from a lattice hadron spectrum calculation using three flavors of dynamical quarks - two light and one strange, and quenched simulations for comparison. These simulations were done using a one-loop Symanzik improved gauge action and an improved Kogut-Susskind quark action. The lattice spacings, and hence also the physical volumes, were tuned to be the same in all the runs to better expose differences due to flavor number. Lattice spacings were tuned using the static quark potential, so as a byproduct we obtain updated results for the effect of sea quarks on the static quark potential. We find indications that the full QCD meson spectrum is in better agreement with experiment than the quenched spectrum. For the 0++ (a0) meson we see a coupling to two pseudoscalar mesons, or a meson decay on the lattice.
Yakymyshyn, Christopher Paul (Seminole, FL); Hamilton, Pamela Jane (Seminole, FL); Brubaker, Michael Allen (Loveland, CO)
2007-12-04
A modular, low weight impedance dropping power supply with battery backup is disclosed that can be connected to a high voltage AC source and provide electrical power at a lower voltage. The design can be scaled over a wide range of input voltages and over a wide range of output voltages and delivered power.
Roepstorff, G
1998-01-01
In a previous paper, the superconnection formalism was used to naturally fit the Higgs field into a U(n) gauge theory where we aimed at the reconstruction of the standard model. The approach provides an alternative to non-commutative geometry. This work is now continued by including matter field (leptons). The essentially new ingredient is the right-handed neutrino field and a new kind of interaction that goes with it. All interactions follow from one Dirac operator associated to a superconnection.
G. Roepstorff
2000-08-17
In a previous paper (hep-th/9801040), the superconnection formalism was used to fit the Higgs field into a U(n) gauge theory with particular emphasis on the n=2 case, aiming at the reconstruction of certain parts of the Standard Model. The approach provides an alternative to the one bases on non-commutative geometry. This work is continued by including matter fields (leptons only). We extend the Standard Model by including the right-handed neutrino field. The possibility of a finite neutrino mass is thus accounted for.
Hirsch, M.; Morisi, S.; Peinado, E.; Valle, J. W. F. [AHEP Group, Institut de Fisica Corpuscular--C.S.I.C./Universitat de Valencia, Edificio Institutos de Paterna, Apartado 22085, E-46071 Valencia (Spain)
2010-12-01
We propose a new motivation for the stability of dark matter (DM). We suggest that the same non-Abelian discrete flavor symmetry which accounts for the observed pattern of neutrino oscillations, spontaneously breaks to a Z{sub 2} subgroup which renders DM stable. The simplest scheme leads to a scalar doublet DM potentially detectable in nuclear recoil experiments, inverse neutrino mass hierarchy, hence a neutrinoless double beta decay rate accessible to upcoming searches, while {theta}{sub 13}=0 gives no CP violation in neutrino oscillations.
Thermodynamics of electroweak matter
A. Gynther
2006-09-21
This paper is a slightly modified version of the introductory part of a PhD thesis, also containing the articles hep-ph/0303019, hep-ph/0510375 and hep-ph/0512177. We provide a short history of the research of electroweak thermodynamics and a brief introduction to the theory as well as to the necessary theoretical tools needed to work at finite temperatures. We then review computations regarding the pressure of electroweak matter at high temperatures (the full expression of the perturbative expansion of the pressure is given in the appendix) and the electroweak phase diagram at finite chemical potentials. Finally, we compare electroweak and QCD thermodynamics.
Dark Matter Velocity Spectroscopy
Eric G. Speckhard; Kenny C. Y. Ng; John F. Beacom; Ranjan Laha
2015-07-31
Dark matter decays or annihilations that produce line-like spectra may be smoking-gun signals. However, even such distinctive signatures can be mimicked by astrophysical or instrumental causes. We show that velocity spectroscopy-the measurement of energy shifts induced by relative motion of source and observer-can separate these three causes with minimal theoretical uncertainties. The principal obstacle has been energy resolution, but upcoming experiments will reach the required 0.1% level. As an example, we show that the imminent Astro-H mission can use Milky Way observations to separate possible causes of the 3.5-keV line. We discuss other applications.
Sikivie, P. (California Univ., Santa Barbara, CA (United States). Inst. for Theoretical Physics Florida Univ., Gainesville, FL (United States). Dept. of Physics)
1992-01-01
The physics of axions is briefly reviewed theoretically, and various constraints on the axion mass are recounted. Then the two main contributions to the present cosmological axion energy density, that due to the realignment of the vacuum during the QCD phase transition and that from axions radiated by cosmic axion strings, are discussed. Next, two detection schemes for axions that are sensitive to different mass ranges, an electromagnetic cavity permeated by a strong magnetic field and a system of superconducting wires embedded in a material transparent to microwave radiation, are described. Finally, the phase space structure of cold dark matter galactic halos is considered. (RWR)
Sikivie, P. [California Univ., Santa Barbara, CA (United States). Inst. for Theoretical Physics]|[Florida Univ., Gainesville, FL (United States). Dept. of Physics
1992-09-01
The physics of axions is briefly reviewed theoretically, and various constraints on the axion mass are recounted. Then the two main contributions to the present cosmological axion energy density, that due to the realignment of the vacuum during the QCD phase transition and that from axions radiated by cosmic axion strings, are discussed. Next, two detection schemes for axions that are sensitive to different mass ranges, an electromagnetic cavity permeated by a strong magnetic field and a system of superconducting wires embedded in a material transparent to microwave radiation, are described. Finally, the phase space structure of cold dark matter galactic halos is considered. (RWR)
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach Home Room NewsInformationJesse BergkampCentermillion toMSDSMaterials andMaterials/Condensed Matter Print
ANALYZER BASICS WHAT IS AN FFT SPECTRUM ANALYZER?
Gustafsson, Torgny
ANALYZER BASICS 2-1 WHAT IS AN FFT SPECTRUM ANALYZER? The SR760 FFT Spectrum Analyzer takes a time on a spectrum analyzer, the harmonic frequencies and amplitudes are displayed with amazing clarity. Another just the total noise amplitude. On a spectrum analyzer, the noise as a function of frequency
Quickest Spectrum Detection Using Hidden Markov Model for Cognitive Radio
Qiu, Robert Caiming
signal and GSM signal are measured using a Spectrum Analyzer (SA). These acquired data are used to trainQuickest Spectrum Detection Using Hidden Markov Model for Cognitive Radio Zhe Chen, Zhen Hu, Robert--The prerequisite of accessing white spectrum is to find and locate it. Our work deals with spectrum detection
MAP: Multiauctioneer Progressive Auction for Dynamic Spectrum Access
Wang, Xinbing
networks. Market-driven spectrum auction has been recognized as an effective way to achieve DSA spectrum bands from POs for their services. However, conventional spectrum auction designs are restricted within the scenario of single auctioneer. In this paper, we study the spectrum auction with multiple
Gravitational wave energy spectrum of hyperbolic encounters
Lorenzo De Vittori; Philippe Jetzer; Antoine Klein
2012-07-23
The emission of gravitational waves is studied for a system of massive objects interacting on hyperbolic orbits within the quadrupole approximation following the work of Capozziello et al. Here we focus on the derivation of an analytic formula for the energy spectrum of the emitted waves. We checked numerically that our formula is in agreement with the two limiting cases for which results were already available: for the eccentricity {\\epsilon} = 1, the parabolic case whose spectrum was computed by Berry and Gair, and the large {\\epsilon} limit with the formula given by Turner.
Gravitational wave energy spectrum of hyperbolic encounters
De Vittori, Lorenzo; Klein, Antoine
2012-01-01
The emission of gravitational waves is studied for a system of massive objects interacting on hyperbolic orbits within the quadrupole approximation following the work of Capozziello et al. Here we focus on the derivation of an analytic formula for the energy spectrum of the emitted waves. We checked numerically that our formula is in agreement with the two limiting cases for which results were already available: for the eccentricity {\\epsilon} = 1, the parabolic case whose spectrum was computed by Berry and Gair, and the large {\\epsilon} limit with the formula given by Turner.
Fan, JiJi; Randall, Lisa; Reece, Matthew
2013-01-01
Based on observational tests and constraints on halo structure, dark matter is generally taken to be cold and essentially collisionless. On the other hand, given the large number of particles and forces in the visible world, a more complex dark sector could be a reasonable or even likely possibility. This hypothesis leads to testable consequences, perhaps portending the discovery of a rich hidden world neighboring our own. We consider a scenario that readily satisfies current bounds that we call Partially Interacting Dark Matter (PIDM). This scenario contains self-interacting dark matter, but it is not the dominant component. Even if PIDM contains only a fraction of the net dark matter density, comparable to the baryonic fraction, the subdominant component's interactions can lead to interesting and potentially observable consequences. Our primary focus will be the special case of Double-Disk Dark Matter (DDDM), in which self-interactions allow the dark matter to lose enough energy to lead to dynamics similar ...
Moskalenko, I V
2006-01-01
We show that a star orbiting close enough to an adiabatically grown supermassive black hole can capture a large number of weakly interacting massive particles (WIMPs) during its lifetime. WIMP annihilation energy release in low- to medium-mass stars is comparable with or even exceeds the luminosity of such stars due to thermonuclear burning. The excessive energy release in the stellar core may result in an evolution scenario different from what is expected for a regular star. The model thus predicts the existence of unusual stars within the central parsec of galactic nuclei. If found, such stars would provide evidence for the existence of particle dark matter. The excess luminosity of such stars attributed to WIMP "burning" can be used to infer the local WIMP matter density. A white dwarf with a highly eccentric orbit around the central black hole may exhibit variations in brightness correlated with the orbital phase. On the other hand, white dwarfs shown to lack such orbital brightness variations can be used...
Dark Matter with (very) heavy SUSY scalars at ILC
M. Berggren; F. Richard; Z. Zhang
2005-10-07
In this paper, six SUSY scenarios with heavy sfermions, mainly based on theoretical arguments and on experimental indications for new physics, are defined. These scenarios, consistent with the amount of dark matter (DM) measured by WMAP, are then analysed in detail providing pertinent examples of the potential of ILC. It is shown that in most cases ILC, with its high precision based on the chargino analysis and in spite of an incomplete coverage of the gaugino and slepton mass spectrum, can predict the amount of DM in our universe with an accuracy which matches the WMAP results.
Condensed Matter and Magnet Science
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
helimagnets and the development of a cryogen-free apparatus for spherical neutron polarimetry." Read more... Cutting-edge condensed matter physics research, high magnetic field...
Solving the Dark Matter Problem
Baltz, Ted
2009-09-01
Cosmological observations have firmly established that the majority of matter in the universe is of an unknown type, called 'dark matter'. A compelling hypothesis is that the dark matter consists of weakly interacting massive particles (WIMPs) in the mass range around 100 GeV. If the WIMP hypothesis is correct, such particles could be created and studied at accelerators. Furthermore they could be directly detected as the primary component of our galaxy. Solving the dark matter problem requires that the connection be made between the two. We describe some theoretical and experimental avenues that might lead to this connection.
Nuclear Matter and Nuclear Dynamics
M Colonna
2009-02-26
Highlights on the recent research activity, carried out by the Italian Community involved in the "Nuclear Matter and Nuclear Dynamics" field, will be presented.
Exploring dark matter microphysics with galaxy surveys
Escudero, Miguel; Vincent, Aaron C; Wilkinson, Ryan J; Boehm, Celine
2015-01-01
We use present cosmological observations and forecasts of future experiments to illustrate the power of large-scale structure (LSS) surveys in probing dark matter (DM) microphysics and unveiling potential deviations from the standard $\\Lambda$CDM scenario. To quantify this statement, we focus on an extension of $\\Lambda$CDM with DM-neutrino scattering, which leaves a distinctive imprint on the angular and matter power spectra. After finding that future CMB experiments (such as COrE+) will not significantly improve the constraints set by the Planck satellite, we show that the next generation of galaxy clustering surveys (such as DESI) could play a leading role in constraining alternative cosmologies and even have the potential to make a discovery. Typically, we find that DESI would be an order of magnitude more sensitive to DM interactions than Planck (if s-wave) and two orders of magnitude (if p-wave), thus probing effects that until now have only been accessible via N-body simulations.
Methods and apparatuses using filter banks for multi-carrier spread-spectrum signals
Moradi, Hussein; Farhang, Behrouz; Kutsche, Carl A
2014-10-14
A transmitter includes a synthesis filter bank to spread a data symbol to a plurality of frequencies by encoding the data symbol on each frequency, apply a common pulse-shaping filter, and apply gains to the frequencies such that a power level of each frequency is less than a noise level of other communication signals within the spectrum. Each frequency is modulated onto a different evenly spaced subcarrier. A demodulator in a receiver converts a radio frequency input to a spread-spectrum signal in a baseband. A matched filter filters the spread-spectrum signal with a common filter having characteristics matched to the synthesis filter bank in the transmitter by filtering each frequency to generate a sequence of narrow pulses. A carrier recovery unit generates control signals responsive to the sequence of narrow pulses suitable for generating a phase-locked loop between the demodulator, the matched filter, and the carrier recovery unit.
Methods and apparatuses using filter banks for multi-carrier spread-spectrum signals
Moradi, Hussein; Farhang, Behrouz; Kutsche, Carl A
2014-05-20
A transmitter includes a synthesis filter bank to spread a data symbol to a plurality of frequencies by encoding the data symbol on each frequency, apply a common pulse-shaping filter, and apply gains to the frequencies such that a power level of each frequency is less than a noise level of other communication signals within the spectrum. Each frequency is modulated onto a different evenly spaced subcarrier. A demodulator in a receiver converts a radio frequency input to a spread-spectrum signal in a baseband. A matched filter filters the spread-spectrum signal with a common filter having characteristics matched to the synthesis filter bank in the transmitter by filtering each frequency to generate a sequence of narrow pulses. A carrier recovery unit generates control signals responsive to the sequence of narrow pulses suitable for generating a phase-locked loop between the demodulator, the matched filter, and the carrier recovery unit.
James Simpson; David Chichester
2011-06-01
Many applications of neutrons for non-invasive measurements began with isotopic sources such as AmBe or Cf-252. Political factors have rendered AmBe undesirable in the United States and other countries, and the supply of Cf-252 is limited and significantly increasing in price every few years. Compact and low-power deuterium-tritium (DT) electronic neutron generators can often provide sufficient flux, but the 14-MeV neutron spectrum is much more energetic (harder) than an isotopic neutron source. A series of MCNP simulations were run to examine the extent to which the 14-MeV DT neutron spectrum could be softened through the use of high-Z and low-Z materials. Some potential concepts of operation require a portable neutron generator system, so the additional weight of extra materials is also a trade-off parameter. Using a reference distance of 30 cm from the source, the average neutron energy can be lowered to be less than that of either AmBe or Cf-252, while obtaining an increase in flux at the reference distance compared to a bare neutron generator. This paper discusses the types and amounts of materials used, the resulting neutron spectra, neutron flux levels, and associated photon production.
Free-fermion Entanglement Spectrum through Wannier Interpolation
Ching Hua Lee; Peng Ye
2014-10-31
Quantum Entanglement plays an ubiquitous role in theoretical physics, from the characterization of novel phases of matter to understanding the efficacy of numerical algorithms. As such, there have been extensive studies on the entanglement spectrum (ES) of free-fermion systems, particularly in the relation between its spectral flow and topological charge pumping. However, far less has been studied about the \\emph{spacing} between adjacent entanglement eigenenergies, which affects the truncation error in numerical computations involving Matrix Product States (MPS) or Projected Entangled-Pair States (PEPS). In this paper, we shall hence derive asymptotic bounds for the ES spacings through an interpolation argument that utilizes known results on Wannier function decay. For translation invariant systems, the Entanglement energies are shown to decay at a rate monotonically related to the complex gap between the filled and occupied bands. This interpolation also demonstrates the one-to-one correspondence between the ES and the edge states. Our results also provide asymptotic bounds for the eigenvalue distribution of certain types of Block Toeplitz matrices common in physics, even for those not arising from entanglement calculations.
The Future of Autism Spectrum Disorders
Brutlag, Doug
The Future of Autism Spectrum Disorders A.R. El-Khattabi Biochemistry 118 Doug Brutlag #12;Background Autism is a Pervasive Developmental Disorder that results from damage to the central nervous exists Significant increase in autism genetics research Sporadic forms of autistic disorder, as well
Spectrum Characterization for Opportunistic Cognitive Radio Systems
Arslan, Hüseyin
transmission parameters of primary users. The primary users are identified by matching the a priory information, the a priory information about the transmission properties of possible primary users, such as transmission better use of available natural re- sources, i.e. the spectrum [1]. The two challenging tasks
Getting Started Guide ESA Series Spectrum Analyzers
Anlage, Steven
Getting Started Guide ESA Series Spectrum Analyzers This manual provides documentation yourself with the symbols and their meaning before operating this analyzer. WARNING Warning denotes, if not correctly performed or adhered to, could result in damage to or destruction of the analyzer. Do not proceed
DYNAMIC SPECTRUM ACCESS IN COGNITIVE RADIO NETWORKS
Katz, Jonathan
, the Federal Communications Commission (FCC) has con- trolled the radio frequency energy spectrum. They license resources. The basic idea is to let people use licensed frequencies, pro- vided they can guarantee interference perceived by the primary license holders will be minimal. With advances in software and cognitive
Green Wireless Cognition: Future Efficient Spectrum Sharing
Shihada, Basem
Green Wireless Cognition: Future Efficient Spectrum Sharing Prof. Basem Shihada MCSE 1 2nd Annual and applications will live in the cloud. Users can access them anytime, anywhere. Ubiquitous highspeed wireless connectivity is a must. Dense, smallrange wireless access points (AP) will become more important than today
Economic Viability of Dynamic Spectrum Management
Huang, Jianwei
Economic Viability of Dynamic Spectrum Management Jianwei Huang Network Communications and Economics Lab Department of Information Engineering The Chinese University of Hong Kong #12;#12;1 Economic economic and policy issue, as it affects the interests of wireless end-users, com- mercial wireless service
Adaptive, full-spectrum solar energy system
Muhs, Jeffrey D.; Earl, Dennis D.
2003-08-05
An adaptive full spectrum solar energy system having at least one hybrid solar concentrator, at least one hybrid luminaire, at least one hybrid photobioreactor, and a light distribution system operably connected to each hybrid solar concentrator, each hybrid luminaire, and each hybrid photobioreactor. A lighting control system operates each component.
Auction-based Spectrum Sharing Jianwei Huang
Berry, Randall
formulate an iterative and distributed bid updating algorithm, and specify conditions under which users wish to purchase a local, relatively short-term data service. The spectrum to be used may efficient multiplexing of data streams from different sources corresponding to different applications
Neutrinos from Kaluza-Klein dark matter in the Sun
Mattias Blennow; Henrik Melbeus; Tommy Ohlsson
2010-01-26
We investigate indirect neutrino signals from annihilations of Kaluza-Klein dark matter in the Sun. Especially, we examine a five- as well as a six-dimensional model, and allow for the possibility that boundary localized terms could affect the spectrum to give different lightest Kaluza-Klein particles, which could constitute the dark matter. The dark matter candidates that are interesting for the purpose of indirect detection of neutrinos are the first Kaluza-Klein mode of the U(1) gauge boson and the neutral component of the SU(2) gauge bosons. Using the DarkSUSY and WimpSim packages, we calculate muon fluxes at an Earth-based neutrino telescope, such as IceCube. For the five-dimensional model, the results that we obtained agree reasonably well with the results that have previously been presented in the literature, whereas for the six-dimensional model, we find that, at tree-level, the results are the same as for the five-dimensional model. Finally, if the first Kaluza-Klein mode of the U(1) gauge boson constitutes the dark matter, IceCube can constrain the parameter space. However, in the case that the neutral component of the SU(2) gauge bosons is the LKP, the signal is too weak to be observed.
Dark Matter annihilations in halos and high-redshift sources of reionization of the universe
Vivian Poulin; Pasquale D. Serpico; Julien Lesgourgues
2015-12-03
It is well known that annihilations in the homogeneous fluid of dark matter (DM) can leave imprints in the cosmic microwave background (CMB) anisotropy power spectrum. However, the relevance of DM annihilations in halos for cosmological observables is still subject to debate, with previous works reaching different conclusions on this point. Also, all previous studies used a single type of parameterization for the astrophysical reionization, and included no astrophysical source for the heating of the intergalactic medium. In this work, we revisit these problems. When standard approaches are adopted, we find that the ionization fraction does exhibit a very particular (and potentially constraining) pattern, but the currently measurable optical depth to reionization is left almost unchanged: In agreement with the most of the previous literature, for plausible halo models we find that the modification of the signal with respect to the one coming from annihilations in the smooth background is tiny, below cosmic variance within currently allowed parameter space. However, if different and probably more realistic treatments of the astrophysical sources of reionization and heating are adopted, a more pronounced effect of the DM annihilation in halos is possible. We thus conclude that within currently adopted baseline models the impact of the virialised DM structures cannot be uncovered by CMB power spectra measurements, but a larger impact is possible if peculiar models are invoked for the redshift evolution of the DM annihilation signal or different assumptions are made for the astrophysical contributions. A better understanding (both theoretical and observational) of the reionization and temperature history of the universe, notably via the 21 cm signal, seems the most promising way for using halo formation as a tool in DM searches, improving over the sensitivity of current cosmological probes.
Standard Neutrino Spectrum from B-8 Decay
John N. Bahcall; E. Lisi; D. E. Alburger; L. De Braeckeleer; S. J. Freedman; J. Napolitano
1996-04-19
We present a systematic evaluation of the shape of the neutrino energy spectrum produced by beta-decay of $^8$B. We place special emphasis on determining the range of uncertainties permitted by existing laboratory data and theoretical ingredients (such as forbidden and radiative corrections). We review and compare the available experimental data on the $^8$B$(\\beta^+){}^8$Be$(2\\alpha)$ decay chain. We analyze the theoretical and experimental uncertainties quantitatively. We give a numerical representation of the best-fit (standard-model) neutrino spectrum, as well as two extreme deviations from the standard spectrum that represent the total (experimental and theoretical) effective $\\pm3\\sigma$ deviations. Solar neutrino experiments that are currently being developed will be able to measure the shape of the $^8$B neutrino spectrum above about 5 MeV. An observed distortion of the $^8$B solar neutrino spectrum outside the range given in the present work could be considered as evidence, at an effective significance level greater than three standard deviations, for physics beyond the standard electroweak model. We use the most recent available experimental data on the Gamow--Teller strengths in the $A=37$ system to calculate the $^8$B neutrino absorption cross section on chlorine: $\\sigma_{\\rm Cl}=(1.14\\pm0.11)\\times10^{-42}$~cm$^2$ ($\\pm3\\sigma$ errors). The chlorine cross section is also given as a function of the neutrino energy. The $^8$B neutrino absorption cross section in gallium is $\\sigma_{\\rm Ga}=(2.46^{+2.1}_{-1.1})\\times10^{-42}$ cm$^2$ ($\\pm3\\sigma$ errors).
Alexander Studenikin
2008-04-09
We present quite a powerful method in investigations of different phenomena that can appear when neutrinos and electrons propagate in background matter. This method implies use of exact solutions of modified Dirac equations that contain the correspondent effective potentials accounting for the matter influence on particles. For several particular cases the exact solutions of modified Dirac and Dirac-Pauli equations for a neutrino and an electron in the background environment of different composition are obtained (the case of magnetized matter is also considered). Neutrino reflection, trapping, neutrino pair creation and annihilation in matter and neutrino energy quantization in a rotating medium are discussed. The neutrino Green functions in matter are also derived. The two recently proposed mechanisms of electromagnetic radiation by a neutrino and an electron in matter (the spin light of neutrino and electron, $SL\
Power-Law and Long-Memory Characteristics of the Atmospheric General Circulation DMITRY I. VYUSHIN memory'' or ``power-law'' model. Such a model fits a temporal spectrum to a single power-law function, which thereby accumulates more power at lower frequencies than an AR1 fit. In this study, several power
The coyote universe extended: Precision emulation of the matter power
Office of Scientific and Technical Information (OSTI)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity of NaturalDukeWakefieldSulfateSciTechtail. (Conference)FeedbackProperties ofTheatmosphere (Journaltransmissionnonlinear
Moskalenko, I V; Moskalenko, Igor V.; Wai, Lawrence L.
2007-01-01
We show that a star orbiting close enough to an adiabatically grown supermassive black hole (SMBH) can capture weakly interacting massive particles (WIMPs) at an extremely high rate. The stellar luminosity due to annihilation of captured WIMPs in the stellar core may be comparable to or even exceed the luminosity of the star due to thermonuclear burning. The model thus predicts the existence of unusual stars, essentially WIMP burners, in the vicinity of a SMBH. We find that the most efficient WIMP burners are stars with degenerate electron cores, e.g. white dwarfs (WDs); such WDs may have a very high surface temperature. If found, such stars would provide evidence for the existence of particle dark matter and can possibly be used to establish its density profile. On the other hand, the lack of such unusual stars may provide constraints on the WIMP density near the SMBH, as well as the WIMP-nucleus scattering and pair annihilation cross-sections.
Igor V. Moskalenko; Lawrence L. Wai
2007-02-24
We show that a star orbiting close enough to an adiabatically grown supermassive black hole (SMBH) can capture weakly interacting massive particles (WIMPs) at an extremely high rate. The stellar luminosity due to annihilation of captured WIMPs in the stellar core may be comparable to or even exceed the luminosity of the star due to thermonuclear burning. The model thus predicts the existence of unusual stars, essentially WIMP burners, in the vicinity of a SMBH. We find that the most efficient WIMP burners are stars with degenerate electron cores, e.g. white dwarfs (WDs); such WDs may have a very high surface temperature. If found, such stars would provide evidence for the existence of particle dark matter and can possibly be used to establish its density profile. On the other hand, the lack of such unusual stars may provide constraints on the WIMP density near the SMBH, as well as the WIMP-nucleus scattering and pair annihilation cross-sections.
Red and blue tilted tensor spectrum from Gibbons-Hawking temperature
Subhendra Mohanty; Akhilesh Nautiyal
2015-01-09
The scale invariant scalar and tensor perturbations, which are predicted from inflation, are eigenmodes in the conformal coordinates. The 'out' observer in the de Sitter space observes a thermal spectrum with a Gibbons-Hawking temperature $H/2\\pi$ of these 'Bunch-Davies' particles. The tensor power spectrum observed in experiments can have an imprint of the Gibbons-Hawking thermal distribution due to the mode mixing between 'in' state conformal coordinates and the coordinate frame of the observer. We find that the the Bunch-Davies modes appear as thermal modes to the asymptotic Minkowski observer in the future and the power spectrum of the gravitational waves is blue-tilted with a spectral index $n_T \\sim 1$ even in the standard slow-roll inflation. On the other hand if the coordinate frame of the observer is taken to be static coordinates, the tensor spectrum is red-tilted with $n_T\\sim -1$. A likelihood analysis shows and find the best fit values of the slow-roll parameters for both cases. We find that the blue-tilted tensor gives a better fit and reconciles the PLANCK upper bound on the tensor-to-scalar ratio, $r <0.11$ with BICEP2 measurement of $r=0.2$. This supports the idea of particle production due to the mode mixing between the initial Bunch-Davies vacuum modes and the asymptotic Minkowski vacuum of the post-inflation universe.
Drennen, Thomas
2012-08-15
POWER LCAT is a software tool used to compare elements of efficiency, cost, and environmental effects between different sources of energy.
Drennen, Thomas
2014-06-27
POWER LCAT is a software tool used to compare elements of efficiency, cost, and environmental effects between different sources of energy.
Energy Matters in Washington State
Collins, Gary S.
Energy Matters in Washington State Energy Matters in Washington State www.energy.wsu.edu/library/ November 2009 #12;905 Plum Street SE, Building 3 P.O. Box 43169 Olympia, Washington 98504-3169 Energy University Extension Energy Program. 905 Plum Street SE, Building 3, P.O. Box 43169, Olympia, Washington
Astronomical Evidence for Dark Matter
Golwala, Sunil
dark matter (assumed non-baryonic) #12;A word about constitutes an energy density from the Friedmann Equation: (Assuming no curvature) #12;Definitions C Critical Density X X/C = 1 => flat universe, what Rotation curve: Virial Theorem: #12;Spiral Galaxies Luminous Matter ~ follows: Asymptotes to constant value
dark matter dark energy inflation
Hu, Wayne
theory dark matter dark energy inflation The National Science Foundation The Kavli Foundation NSF Site Review November 28-29, 2005 #12;dark matter dark energy inflation NSF Site Visit November 28 - 29, 2005The National Science Foundation The Kavli Foundation The Theoretical Web UHE cosmic rays B
Randy Lewis
2014-11-26
Several collaborations have recently performed lattice calculations aimed specifically at dark matter, including work with SU(2), SU(3), SU(4) and SO(4) gauge theories to represent the dark sector. Highlights of these studies are presented here, after a reminder of how lattice calculations in QCD itself are helping with the hunt for dark matter.
Charmonium mass in nuclear matter
Lee, S. H.; Ko, Che Ming.
2003-01-01
The mass shift of charmonium states in nuclear matter is studied in the perturbative QCD approach. The leading-order effect due to the change of gluon condensate in nuclear matter is evaluated using the leading-order QCD formula, while the higher...
Quantum vacuum and dark matter
Dragan Slavkov Hajdukovic
2011-11-21
Recently, the gravitational polarization of the quantum vacuum was proposed as alternative to the dark matter paradigm. In the present paper we consider four benchmark measurements: the universality of the central surface density of galaxy dark matter haloes, the cored dark matter haloes in dwarf spheroidal galaxies, the non-existence of dark disks in spiral galaxies and distribution of dark matter after collision of clusters of galaxies (the Bullet cluster is a famous example). Only some of these phenomena (but not all of them) can (in principle) be explained by the dark matter and the theories of modified gravity. However, we argue that the framework of the gravitational polarization of the quantum vacuum allows the understanding of the totality of these phenomena.
Joint Spectrum Allocation and Scheduling for Fair Spectrum Sharing in Cognitive Radio
Misra, Satyajayant
unlicensed wireless users (a.k.a secondary users) to sense and access the under-utilized spectrum opportunistically even if it is licensed, as long as the licensed wireless users (a.k.a primary users
Role of atmospheric ammonia in particulate matter formation in Houston during summertime
the measurements. Point sources (e.g., power plant and chemical plant) might be potential contributors number concentrations were predicted by the SAM-TOMAS model downwind of a large coal-fired power plant 2013 Keywords: Ammonia Particulate matter Gas-particle partitioning Aerosol nucleation a b s t r a c
Nuclear-matter--quark-matter phase diagram with strangeness
Barz, H. W.; Friman, B. L.; Knoll, J.; Schulz, H.
1989-07-01
A phenomenological equation of state of strongly interacting matter, including strange degrees of freedom, is presented. It is shown that the hyperon and kaon interactions must be included, in order to obtain a reasonable description of the deconfinement transition at high baryon densities. The consequences of kaon condensation on the nuclear-matter--quark-matter phase diagram are explored. The relative particle abundances obtained in an isentropic expansion of a blob of quark-gluon plasma are presented for different initial conditions. Implications for ultrarelativistic heavy-ion collisions are briefly discussed.
Hickam, Christopher Dale (Glasford, IL)
2008-03-18
A power system includes a prime mover, a transmission, and a fluid coupler having a selectively engageable lockup clutch. The fluid coupler may be drivingly connected between the prime mover and the transmission. Additionally, the power system may include a motor/generator drivingly connected to at least one of the prime mover and the transmission. The power-system may also include power-system controls configured to execute a control method. The control method may include selecting one of a plurality of modes of operation of the power system. Additionally, the control method may include controlling the operating state of the lockup clutch dependent upon the mode of operation selected. The control method may also include controlling the operating state of the motor/generator dependent upon the mode of operation selected.
PROSPECT - A precision oscillation and spectrum experiment
T. J. Langford
2014-12-22
Segmented antineutrino detectors placed near a compact research reactor provide an excellent opportunity to probe short-baseline neutrino oscillations and precisely measure the reactor antineutrino spectrum. Close proximity to a reactor combined with minimal overburden yield a high background environment that must be managed through shielding and detector technology. PROSPECT is a new experimental effort to detect reactor antineutrinos from the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory, managed by UT Battelle for the U.S. Department of Energy. The detector will use novel lithium-loaded liquid scintillator capable of neutron/gamma pulse shape discrimination and neutron capture tagging. These enhancements improve the ability to identify neutrino inverse-beta decays and reject background events in analysis. Results from these efforts will be covered along with their implications for an oscillation search and a precision spectrum measurement.
PROSPECT - A precision oscillation and spectrum experiment
,
2015-01-01
Segmented antineutrino detectors placed near a compact research reactor provide an excellent opportunity to probe short-baseline neutrino oscillations and precisely measure the reactor antineutrino spectrum. Close proximity to a reactor combined with minimal overburden yield a high background environment that must be managed through shielding and detector technology. PROSPECT is a new experimental effort to detect reactor antineutrinos from the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory, managed by UT Battelle for the U.S. Department of Energy. The detector will use novel lithium-loaded liquid scintillator capable of neutron/gamma pulse shape discrimination and neutron capture tagging. These enhancements improve the ability to identify neutrino inverse-beta decays and reject background events in analysis. Results from these efforts will be covered along with their implications for an oscillation search and a precision spectrum measurement.
Sommaruga, Ruben
dissolved organic matter by solar UV radiation causes rapid changes in bacterial community composition of the lagoon was exposed to different regions of the solar spectrum (full solar radiation, UV-A + PAR, PAR increases significantly after exposure of CDOM to solar radiation.4,9,10,1113 This increase in bacterial
Laser Driven Dynamic Loading of Condensed Matter
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Laser Driven Dynamic Loading of Condensed Matter Laser Driven Dynamic Loading of Condensed Matter Advanced diagnostics of experiments covering many orders of magnitude in strain...
MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; SOLID STATE...
Office of Scientific and Technical Information (OSTI)
Open problems in condensed matter physics, 1987 Falicov, L.M. 75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; SOLID STATE PHYSICS; RESEARCH PROGRAMS;...
Ultrafast Spectroscopy of Warm Dense Matter
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
of planet formation and structures as well as the evolution of an imploding inertial fusion capsule depends on our understanding of matter in the complex warm dense matter...
John Ellis
2011-06-15
The prospects for detecting a candidate supersymmetric dark matter particle at the LHC are reviewed, and compared with the prospects for direct and indirect searches for astrophysical dark matter. The discussion is based on a frequentist analysis of the preferred regions of the Minimal supersymmetric extension of the Standard Model with universal soft supersymmetry breaking (the CMSSM). LHC searches may have good chances to observe supersymmetry in the near future - and so may direct searches for astrophysical dark matter particles, whereas indirect searches may require greater sensitivity, at least within the CMSSM.
The Unification and Cogeneration of Dark Matter and Baryonic Matter
S. M. Barr
2011-09-18
In grand unified theories with gauge groups larger than SU(5), the multiplets that contain the known quarks and leptons also contain fermions that are singlets under the Standard Model gauge group. Some of these could be the dark matter of the universe. Grand unified theories can also have accidental U(1) global symmetries (analogous to B-L in minimal SU(5)) that can stabilize dark matter. These ideas are illustrated in an SU(6) model.
The Unification and Cogeneration of Dark Matter and Baryonic Matter
Barr, S M
2011-01-01
In grand unified theories with gauge groups larger than SU(5), the multiplets that contain the known quarks and leptons also contain fermions that are singlets under the Standard Model gauge group. Some of these could be the dark matter of the universe. Grand unified theories can also have accidental U(1) global symmetries (analogous to B-L in minimal SU(5)) that can stabilize dark matter. These ideas are illustrated in an SU(6) model.
NEAR-MILLIMETER SPECTRUM OF THE MICROWAVE BACKGROUND
Woody, D.P.
2013-01-01
+o, 14 z2.06 Table 3. Microwave Measurements of the CMBMILLIMETER SPECTRUM OF THE MICROWAVE BACKGROUND D. P. WoodyMILLIMETER SPECTRUM OF THE MICROWAVE BACKGROUND D. P. Woody1
Enhancing spectrum utilization through cooperation and cognition in wireless systems
Rahul, Hariharan Shankar, 1975-
2013-01-01
We have seen a proliferation of wireless technologies and devices in recent years. The resulting explosion of wireless demand has put immense pressure on available spectrum. Improving spectrum utilization is therefore ...
Dark matter and halo bispectrum in redshift space: theory and applications
Gil-Marín, Héctor; Percival, Will [Institute of Cosmology and Gravitation, University of Portsmouth, Dennis Sciama Building, Portsmouth PO1 3FX (United Kingdom); Wagner, Christian [Max-Planck-Institut für Astrophysik, Karl-Schwarzschild Str. 1, 85741 Garching (Germany); Noreńa, Jorge [Department of Theoretical Physics and Center for Astroparticle Physics (CAP), 24 quai E. Ansermet, CH-1211 Geneva 4 (Switzerland); Verde, Licia, E-mail: hector.gil@port.ac.uk, E-mail: cwagner@mpa-garching.mpg.de, E-mail: jorge.norena@unige.ch, E-mail: liciaverde@icc.ub.edu, E-mail: will.percival@port.ac.uk [ICREA Institució Catalana de Recerca i Estudis Avançats, Passeig Lluís Companys 23, E-08010 Barcelona (Spain)
2014-12-01
We present a phenomenological modification of the standard perturbation theory prediction for the bispectrum in redshift space that allows us to extend the model to mildly non-linear scales over a wide range of redshifts, z?1.5. Our model require 18 free parameters that are fitted to N-body simulations using the shapes k{sub 2}/k{sub 1}=1, 1.5, 2.0, 2.5. We find that we can describe the bispectrum of dark matter particles with ?5% accuracy for k{sub i}?<0.10 h/Mpc at z=0, for k{sub i}?<0.15 h/Mpc at z=0.5, for k{sub i}?<0.17 h/Mpc at z=1.0 and for k{sub i}?<0.20 h/Mpc at z=1.5. For very squeezed triangles with k{sub 1}=k{sub 2}?>0.1 hMpc{sup -1} and k{sub 3}?0.02 hMpc{sup -1}, however, neither SPT nor the proposed fitting formula are able to describe the measured dark matter bispectrum with this accuracy. We show that the fitting formula is sufficiently general that can be applied to other intermediate shapes such as k{sub 2}/k{sub 1}=1.25, 1.75, and 2.25. We also test that the fitting formula is able to describe with similar accuracy the bispectrum of cosmologies with different ?{sub m}, in the range 0.2?< ?{sub m} ?< 0.4, and consequently with different values of the logarithmic grow rate f at z=0, 0.4?< f(z=0) ?< 0.6. We apply this new formula to recover the bias parameters, f and ?{sub 8}, by combining the redshift space power spectrum monopole and quadrupole with the bispectrum monopole for both dark matter particles and haloes. We find that the combination of these three statistics can break the degeneracy between b{sub 1}, f and ?{sub 8}. For dark matter particles the new model can be used to recover f and ?{sub 8} with ?1% accuracy. For dark matter haloes we find that f and ?{sub 8} present larger systematic shifts, ?10%. The systematic offsets arise because of limitations in the modelling of the interplay between bias and redshift space distortions, and represent a limitation as the statistical errors of forthcoming surveys reach this level. Conveniently, we find that these residual systematics are mitigated for combinations of parameters. In particular, the quantity f?{sub 8} is still recovered with ?1% accuracy for the particular halo population and cosmology studied. The improvement on the modelling of the bispectrum presented in this paper will be useful for extracting information from current and future galaxy surveys.
Cohen, Israel
not perform well in low SNR conditions. Furthermore, the signal segments used for building the histograms466 IEEE TRANSACTIONS ON SPEECH AND AUDIO PROCESSING, VOL. 11, NO. 5, SEPTEMBER 2003 Noise Spectrum signal-to-noise ratio (SNR). The noise estimate is obtained by averaging past spectral power values
Full Spectrum Boost in Nanoparticle Solar Cells UC Davis/Theory: F.Gygi, M.Voros, GTZ
designs are needed GaAs 29% Alta Devices HIT c-Si cell 26% Panasonic, SunPower Thin film CdTe 20Full Spectrum Boost in Nanoparticle Solar Cells UC Davis/Theory: F.Gygi, M.Voros, GTZ UC Davis% First Solar Organic solar cells 12% Sumitomo #12;Solar Energy Conversion: Basics 5 1. No absorption
Improving earthquake source spectrum estimation using multitaper techniques
Prieto, Germán A.
2007-01-01
65 Uncertainties in earthquake source spectrum estimation1. Earthquake physics . . . . . . . . . . . . . . .1. Static and dynamic earthquake parameters 2. Scaling of
Multicarrier orthogonal spread-spectrum (MOSS) data communications
Smith, Stephen F. (London, TN); Dress, William B. (Camas, WA)
2008-01-01
Systems and methods are described for multicarrier orthogonal spread-spectrum (MOSS) data communication. A method includes individually spread-spectrum modulating at least two of a set of orthogonal frequency division multiplexed carriers, wherein the resulting individually spread-spectrum modulated at least two of a set of orthogonal frequency division multiplexed carriers are substantially mutually orthogonal with respect to both frequency division multiplexing and spread-spectrum modulation.
Dark Matter Detectors as Dark Photon Helioscopes
Haipeng An; Maxim Pospelov; Josef Pradler
2013-08-20
Light new particles with masses below 10 keV, often considered as a plausible extension of the Standard Model, will be emitted from the solar interior, and can be detected on the Earth with a variety of experimental tools. Here we analyze the new "dark" vector state V, a massive vector boson mixed with the photon via an angle kappa, that in the limit of the small mass m_V has its emission spectrum strongly peaked at low energies. Thus, we utilize the constraints on the atomic ionization rate imposed by the results of the XENON10 experiment to set the limit on the parameters of this model: kappa times m_VeV. This makes low-threshold Dark Matter experiments the most sensitive dark vector helioscopes, as our result not only improves current experimental bounds from other searches by several orders of magnitude, but also surpasses even the most stringent astrophysical and cosmological limits in a seven-decade-wide interval of m_V. We generalize this approach to other light exotic particles, and set the most stringent direct constraints on "mini-charged" particles.
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would like submit theCovalent Bonding Low-Cost2 DOE HQSiteo nspectroscopic resultsDark Energy:
Carreras, B. A.; Physics Department, College of Natural Science and Mathematics and Geophysical Institute, University of Alaska, Fairbanks, Alaska 99775; Physics Department, Universidad Carlos III de Madrid, Madrid ; Newman, D. E.; Dobson, Ian
2014-06-15
Failures of the complex infrastructures society depends on having enormous human and economic cost that poses the question: Are there ways to optimize these systems to reduce the risks of failure? A dynamic model of one such system, the power transmission grid, is used to investigate the risk from failure as a function of the system size. It is found that there appears to be optimal sizes for such networks where the risk of failure is balanced by the benefit given by the size.
2010-01-01
be inherently safe and environmentally benign. These realities of today's world are among the reasons that lead to serious interest in deploying nuclear power as a sustainable energy source. Today's nuclear reactors are safe and highly efficient energy systems...
Arnold, Mobius; Ives, Robert Lawrence
2006-09-05
A power combiner for the combining of symmetric and asymmetric traveling wave energy comprises a feed waveguide having an input port and a launching port, a reflector for reflecting launched wave energy, and a final waveguide for the collection and transport of launched wave energy. The power combiner has a launching port for symmetrical waves which comprises a cylindrical section coaxial to the feed waveguide, and a launching port for asymmetric waves which comprises a sawtooth rotated about a central axis.
LWA Equipment RF Emissions: Spectrum Analyzers and Ylva Pihlstrm, UNM
Ellingson, Steven W.
1 LWA Equipment RF Emissions: Spectrum Analyzers and Laptops Ylva Pihlström, UNM 8/27/06 Summary I be used at the LWDA site during standard VLA operations. Two brands of spectrum analyzers and laptop are therefore considered typical of spectrum analyzers and laptops. The results of the measurements suggest
Designing Truthful Spectrum Double Auctions with Local Markets
Li, Baochun
Designing Truthful Spectrum Double Auctions with Local Markets Wei Wang, Student Member, IEEE, Ben pieces in the market. We design a spectrum double auction that incorporates such locality in spectrum markets, while keeping the auction economically robust and computationally efficient. Our designs
Truthful Auction Mechanisms with Performance Guarantee in Secondary Spectrum Markets
Li, Xiang-Yang
is to design truthful auction mechanisms that maximize either the overall social efficiency of new users (a.k.a buyers) or the revenue of the spectrum owner (a.k.a seller). Given that the optimal conflict methods is spectrum auction, which gives incentive for a spectrum owner (a.k.a seller) to sublease
Cryptographic Link Signatures for Spectrum Usage Authentication in Cognitive Radio
Du, Wenliang "Kevin"
Cryptographic Link Signatures for Spectrum Usage Authentication in Cognitive Radio Xi Tan, Kapil the usage of the spectrum to avoid interference with the primary user. However, achieving a trustworthy this attack, there should be a way to authenticate primary users' spectrum usage. We propose a method
Physical Protection of Classified Matter
Broader source: Directives, Delegations, and Requirements [Office of Management (MA)]
1988-02-03
The order establishes policy and objectives for physical protection of classified matter. This directive does not cancel another directive. Chg 1, 7-30-93. Canceled by 5632.1C.
Mondragon, Antonio Richard
2009-05-15
was originally motivated by an unconventional fundamental theory, but which in this dissertation is defined as matter which has a nonzero minimum velocity. Furthermore, the present investigation evolved into the broader goal of exploring the properties of Lorentz...
Energy Matters: Our Energy Independence
Office of Energy Efficiency and Renewable Energy (EERE)
In this installment of the livechat series "Energy Matters," Dr. Arun Majumdar takes questions from the public about the investments we're making today that will move us off of foreign oil and...
Strongly interacting parton matter equilibration
Ozvenchuk, V.; Linnyk, O.; Bratkovskaya, E.; Gorenstein, M.; Cassing, W.
2012-07-15
We study the kinetic and chemical equilibration in 'infinite' parton matter within the Parton-Hadron-String Dynamics transport approach. The 'infinite' matter is simulated within a cubic box with periodic boundary conditions initialized at different energy densities. Particle abundances, kinetic energy distributions, and the detailed balance of the off-shell quarks and gluons in the strongly-interacting quarkgluon plasma are addressed and discussed.
Dark Matter Triggers of Supernovae
Peter W. Graham; Surjeet Rajendran; Jaime Varela
2015-05-17
The transit of primordial black holes through a white dwarf causes localized heating around the trajectory of the black hole through dynamical friction. For sufficiently massive black holes, this heat can initiate runaway thermonuclear fusion causing the white dwarf to explode as a supernova. The shape of the observed distribution of white dwarfs with masses up to $1.25 M_{\\odot}$ rules out primordial black holes with masses $\\sim 10^{19}$ gm - $10^{20}$ gm as a dominant constituent of the local dark matter density. Black holes with masses as large as $10^{24}$ gm will be excluded if recent observations by the NuStar collaboration of a population of white dwarfs near the galactic center are confirmed. Black holes in the mass range $10^{20}$ gm - $10^{22}$ gm are also constrained by the observed supernova rate, though these bounds are subject to astrophysical uncertainties. These bounds can be further strengthened through measurements of white dwarf binaries in gravitational wave observatories. The mechanism proposed in this paper can constrain a variety of other dark matter scenarios such as Q balls, annihilation/collision of large composite states of dark matter and models of dark matter where the accretion of dark matter leads to the formation of compact cores within the star. White dwarfs, with their astronomical lifetimes and sizes, can thus act as large space-time volume detectors enabling a unique probe of the properties of dark matter, especially of dark matter candidates that have low number density. This mechanism also raises the intriguing possibility that a class of supernova may be triggered through rare events induced by dark matter rather than the conventional mechanism of accreting white dwarfs that explode upon reaching the Chandrasekhar mass.
Cosmology, Thermodynamics and Matter Creation
J. A. S. Lima; M. O. Calvao; I. Waga
2007-08-24
Several approaches to the matter creation problem in the context of cosmological models are summarily reviewed. A covariant formulation of the general relativistic imperfect simple fluid endowed with a process of matter creation is presented. By considering the standard big bang model, it is shown how the recent results of Prigogine et alii \\cite{1} can be recovered and, at the same time their limits of validity are explicited.
Spin Dependence of Dark Matter Scattering
Vernon Barger; Wai-Yee Keung; Gabe Shaughnessy
2008-06-11
New experiments designed to discover a weakly interacting dark matter (DM) particle via spin dependent scattering can distinguish models of electroweak symmetry breaking. The plane of spin dependent versus spin independent DM scattering cross sections is a powerful model diagnostic. We detail representative predictions of mSUGRA, singlet extended SM and MSSM, a new Dirac neutrino, Littlest Higgs with T-parity (LHT) and Minimal Universal Extra Dimensions (mUED) models. Of these models, the nMSSM has the largest spin dependent (SD) cross section. It has a very light neutralino which would give lower energy nuclear recoils. The Focus Point region of mSUGRA, mUED and the right handed neutrino also predict a very large SD cross section and predict a large signal of high energy neutrinos in the IceCube experiment from annihilations of dark matter in the Sun. We also describe a model independent treatment of the scattering of DM particles of different intrinsic spins.
The Cold Dark Matter Search test stand warm electronics card
Hines, Bruce; Hansen, Sten; Huber, Martin; Kiper, Terry; Rau, Wolfgang; Saab, Tarek; Seitz, Dennis; Sundqvist, Kyle; Mandic, Vuk; /Minnesota U.
2010-11-01
A card which does the signal processing for four SQUID amplifiers and two charge sensitive channels is described. The card performs the same functions as is presently done with two custom 9U x 280mm Eurocard modules, a commercial multi-channel VME digitizer, a PCI to GPIB interface, a PCI to VME interface and a custom built linear power supply. By integrating these functions onto a single card and using the power over Ethernet standard, the infrastructure requirements for instrumenting a Cold Dark Matter Search (CDMS) detector test stand are significantly reduced.
8Li electron spectrum versus 8B neutrino spectrum: implications for the Sudbury Neutrino Observatory
G. Jonkmans; I. S. Towner; B. Sur
1998-02-25
The sensitivity of the Sudbury Neutrino Observatory (SNO) to measure the shape of the recoil electron spectrum in the charged-current reaction of $^{8}$B solar neutrinos interacting with deuterium can be improved if the results of a $^{8}$Li beta-decay calibration experiment are included in the test. We calculate an improvement in sensitivity, under certain idealistic assumptions, of about a factor of 2, sufficient to resolve different neutrino-oscillation solutions to the solar-neutrino problem. We further examine the role of recoil and radiative corrections on both the $^{8}$B neutrino spectrum and the $^{8}$Li electron spectrum and conclude that the influence of these effects on the ratio of the two spectra as measured by SNO is very small.
ADAPTIVE FULL-SPECTRUM SOLOR ENERGY SYSTEMS
Byard D. Wood
2004-04-01
This RD&D project is a three year team effort to develop a hybrid solar lighting (HSL) system that transports solar light from a paraboloidal dish concentrator to a luminaire via a large core polymer fiber optic. The luminaire can be a device to distribute sunlight into a space for the production of algae or it can be a device that is a combination of solar lighting and electric lighting. A benchmark prototype system has been developed to evaluate the HSL system. Sunlight is collected using a one-meter paraboloidal concentrator dish with two-axis tracking. A secondary mirror consisting of eight planar-segmented mirrors directs the visible part of the spectrum to eight fibers (receiver) and subsequently to eight luminaires. This results in about 8,200 lumens incident at each fiber tip. Each fiber can illuminate about 16.7 m{sup 2} (180 ft{sup 2}) of office space. The IR spectrum is directed to a thermophotovoltaic (TPV) array to produce electricity. During this reporting period, the project team made advancements in the design of the second generation (Alpha) system. For the Alpha system, the eight individual 12 mm fibers have been replaced with a centralized bundle of 3 mm fibers. The TRNSYS Full-Spectrum Solar Energy System model has been updated and new components have been added. The TPV array and nonimaging device have been tested and progress has been made in the fiber transmission models. A test plan was developed for both the high-lumen tests and the study to determine the non-energy benefits of daylighting. The photobioreactor team also made major advancements in the testing of model scale and bench top lab-scale systems.
Frequency spectrum analyzer with phase-lock
Boland, Thomas J. (Idaho Falls, ID)
1984-01-01
A frequency-spectrum analyzer with phase-lock for analyzing the frequency and amplitude of an input signal is comprised of a voltage controlled oscillator (VCO) which is driven by a ramp generator, and a phase error detector circuit. The phase error detector circuit measures the difference in phase between the VCO and the input signal, and drives the VCO locking it in phase momentarily with the input signal. The input signal and the output of the VCO are fed into a correlator which transfers the input signal to a frequency domain, while providing an accurate absolute amplitude measurement of each frequency component of the input signal.
A New Solar Irradiance Reference Spectrum
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantity ofkandz-cm11 Outreach HomeA Better Anode Design to Improve Lithium-Ion Batteries PrintA New Solar Irradiance Reference Spectrum
PROBING DENSE NUCLEAR MATTER VIA NUCLEAR COLLISIONS
Stocker, H.
2012-01-01
shocked nuclear matter during the compression and expansionand isentropic expansion were valid in nuclear collisions.
Power Spectra to 1% Accuracy between Dynamical Dark Energy Cosmologies
Matthew J. Francis; Geraint F. Lewis; Eric V. Linder
2007-04-03
For dynamical dark energy cosmologies we carry out a series of N-body gravitational simulations, achieving percent level accuracy in the relative mass power spectra at any redshift. Such accuracy in the power spectrum is necessary for next generation cosmological mass probes. Our matching procedure reproduces the CMB distance to last scattering and delivers subpercent level power spectra at z=0 and z~3. We discuss the physical implications for probing dark energy with surveys of large scale structure.
Low Power Design Low PowerLow Power
Pedram, Massoud
Low Power Design USC/LPCAD Page 1 USCUSC Low PowerLow Power CADCAD MassoudMassoud PedramPedram High-Level Design Challenges and Solutions for Low Power Systems Massoud Pedram University of Southern California Department of EE-Systems Los Angeles CA 90089-256 Email: massoud@zugros.usc.edu USCUSC Low PowerLow Power
Possibility of Testing the Light Dark Matter Hypothesis with the Alpha Magnetic Spectrometer
Hooper, Dan; Xue, Wei
2013-01-01
The spectrum and morphology of gamma-rays from the Galactic Center and the spectrum of synchrotron emission observed from the Milky Way's radio filaments have each been interpreted as possible signals of $\\sim$7-10 GeV dark matter particles annihilating in the Inner Galaxy. In dark matter models capable of producing these signals, the annihilations should also generate significant fluxes of $\\sim$7-10 GeV positrons which can lead to a distinctive bump-like feature in local cosmic ray positron spectrum. In this letter, we show that while such a feature would be difficult to detect with PAMELA, it would likely be identifiable by the currently operating AMS experiment. As no known astrophysical sources or mechanisms are likely to produce such a sharp feature, the observation of a positron bump at around 7-10 GeV would significantly strengthen the case for a dark matter interpretation of the reported gamma-ray and radio anomalies.
Chen, Chih-Kai
2012-01-01
and K. Yao, “Energy-based Cooperative Spectrum Sensing forof distributed energy-based cooperative spectrum sensingwe focus on the energy-based cooperative spectrum sensing
The matter in extreme conditions instrument at the Linac Coherent Light Source
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Nagler, Bob; Arnold, Brice; Bouchard, Gary; Boyce, Richard F.; Boyce, Richard M.; Callen, Alice; Campell, Marc; Curiel, Ruben; Galtier, Eric; Garofoli, Justin; et al
2015-04-21
The LCLS beam provides revolutionary capabilities for studying the transient behavior of matter in extreme conditions. The particular strength of the Matter in Extreme Conditions instrument is that it combines the unique LCLS beam with high-power optical laser beams, and a suite of dedicated diagnostics tailored for this field of science. In this paper an overview of the beamline, the capabilities of the instrumentation, and selected highlights of experiments and commissioning results are presented.
Reheating signature in the gravitational wave spectrum from self-ordering scalar fields
Sachiko Kuroyanagi; Takashi Hiramatsu; Jun'ichi Yokoyama
2015-09-28
We investigate the imprint of reheating on the gravitational wave spectrum produced by self-ordering of multi-component scalar fields after a global phase transition. The equation of state of the Universe during reheating, which usually has different behaviour from that of a radiation-dominated Universe, affects the evolution of gravitational waves through the Hubble expansion term in the equations of motion. This gives rise to a different power-law behavior of frequency in the gravitational wave spectrum. The reheating history is therefore imprinted in the shape of the spectrum. We perform $512^3$ lattice simulations to investigate how the ordering scalar field reacts to the change of the Hubble expansion and how the reheating effect arises in the spectrum. We also compare the result with inflation-produced gravitational waves, which has a similar spectral shape, and discuss whether it is possible to distinguish the origin between inflation and global phase transition by detecting the shape with future direct detection gravitational wave experiments such as DECIGO.
Reheating signature in the gravitational wave spectrum from self-ordering scalar fields
Kuroyanagi, Sachiko; Yokoyama, Jun'ichi
2015-01-01
We investigate the imprint of reheating on the gravitational wave spectrum produced by self-ordering of multi-component scalar fields after a global phase transition. The equation of state of the Universe during reheating, which usually has different behaviour from that of a radiation-dominated Universe, affects the evolution of gravitational waves through the Hubble expansion term in the equations of motion. This gives rise to a different power-law behavior of frequency in the gravitational wave spectrum. The reheating history is therefore imprinted in the shape of the spectrum. We perform $512^3$ lattice simulations to investigate how the ordering scalar field reacts to the change of the Hubble expansion and how the reheating effect arises in the spectrum. We also compare the result with inflation-produced gravitational waves, which has a similar spectral shape, and discuss whether it is possible to distinguish the origin between inflation and global phase transition by detecting the shape with future direc...
Window in the dark matter exclusion limits
Zaharijas, Gabrijela; Farrar, Glennys R. [Center for Cosmology and Particle Physics, New York University, New York, New York 10003 (United States)
2005-10-15
We consider the cross section limits for light dark matter cadnidates (m=0.4 to 10 GeV). We calculate the interaction of dark matter in the crust above underground dark matter detectors and find that in the intermediate cross section range, the energy loss of dark matter is sufficient to fall below the energy threshold of current underground experiments. This implies the existence of a window in the dark matter exclusion limits in the micro-barn range.
Miller, David H. (Redondo Beach, CA); Korich, Mark D. (Chino Hills, CA); Smith, Gregory S. (Woodland Hills, CA)
2011-11-15
Power inverters include a frame and a power module. The frame has a sidewall including an opening and defining a fluid passageway. The power module is coupled to the frame over the opening and includes a substrate, die, and an encasement. The substrate includes a first side, a second side, a center, an outer periphery, and an outer edge, and the first side of the substrate comprises a first outer layer including a metal material. The die are positioned in the substrate center and are coupled to the substrate first side. The encasement is molded over the outer periphery on the substrate first side, the substrate second side, and the substrate outer edge and around the die. The encasement, coupled to the substrate, forms a seal with the metal material. The second side of the substrate is positioned to directly contact a fluid flowing through the fluid passageway.
JiJi Fan; Andrey Katz; Lisa Randall; Matthew Reece
2013-07-31
Based on observational constraints on large scale structure and halo structure, dark matter is generally taken to be cold and essentially collisionless. On the other hand, given the large number of particles and forces in the visible world, a more complex dark sector could be a reasonable or even likely possibility. This hypothesis leads to testable consequences, perhaps portending the discovery of a rich hidden world neighboring our own. We consider a scenario that readily satisfies current bounds that we call Partially Interacting Dark Matter (PIDM). This scenario contains self-interacting dark matter, but it is not the dominant component. Even if PIDM contains only a fraction of the net dark matter density, comparable to the baryonic fraction, the subdominant component's interactions can lead to interesting and potentially observable consequences. Our primary focus will be the special case of Double-Disk Dark Matter (DDDM), in which self-interactions allow the dark matter to lose enough energy to lead to dynamics similar to those in the baryonic sector. We explore a simple model in which DDDM can cool efficiently and form a disk within galaxies, and we evaluate some of the possible observational signatures. The most prominent signal of such a scenario could be an enhanced indirect detection signature with a distinctive spatial distribution. Even though subdominant, the enhanced density at the center of the galaxy and possibly throughout the plane of the galaxy can lead to large boost factors, and could even explain a signature as large as the 130 GeV Fermi line. Such scenarios also predict additional dark radiation degrees of freedom that could soon be detectable and would influence the interpretation of future data, such as that from Planck and from the Gaia satellite. We consider this to be the first step toward exploring a rich array of new possibilities for dark matter dynamics.
Murray, F.
1986-01-01
, will be the use of the ASTM Theoretical Steam Rate Tables. In addition, the author's experience regarding the minimum size for power recovery units that are economic in a Culf Coast plant will be presented. INTROD\\Jr.'rION When surveying an operation...)' The pressure ~ecompression term(~2) k~l, is used in the equat10n in a manner 1 which reduces the power recovery as calculated by the first term of the equation. From a practical view a decompression ra~~y ~0.3 is a good screening point. Note...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power AdministrationRobust,Field-effect Photovoltaics -7541 *ImpactScience(TechnicalFor Milwaukee, BySoft Solar Power
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power AdministrationRobust,Field-effectWorkingLos Alamos verifies largest single| National1958,1CaseYakama Power May
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Homesum_a_epg0_fpd_mmcf_m.xls" ,"Available from WebQuantityBonneville Power Administration would likeUniverse (Journal Article)Forthcoming UpgradesArea:Benefits of FES Â»Power
Angular Power Spectra with Finite Counts
Sheldon S. Campbell
2014-10-24
Angular anisotropy techniques for cosmic diffuse radiation maps are powerful probes, even for quite small data sets. A popular observable is the angular power spectrum; we present a detailed study applicable to any unbinned source skymap S(n) from which N random, independent events are observed. Its exact variance, which is due to the finite statistics, depends only on S(n) and N; we also derive an unbiased estimator of the variance from the data. First-order effects agree with previous analytic estimates. Importantly, heretofore unidentified higher-order effects are found to contribute to the variance and may cause the uncertainty to be significantly larger than previous analytic estimates---potentially orders of magnitude larger. Neglect of these higher-order terms, when significant, may result in a spurious detection of the power spectrum. On the other hand, this would indicate the presence of higher-order spatial correlations, such as a large bispectrum, providing new clues about the sources. Numerical simulations are shown to support these conclusions. Applying the formalism to an ensemble of Gaussian-distributed skymaps, the noise-dominated part of the power spectrum uncertainty is significantly increased at high multipoles by the new, higher-order effects. This work is important for harmonic analyses of the distributions of diffuse high-energy gamma-rays, neutrinos, and charged cosmic rays, as well as for populations of sparse point sources such as active galactic nuclei.
Carver, Jeffrey C.
NOISE CONTROL METHODS FOR A RECIPROCATING AIR COMPRESSOR USED IN FUEL CELL AUXILIARY POWER UNIT What is Fuel Cell APU? Why use APU? To reduce overall noise levels in a fuel cell auxiliary power unit (APU) Main Components Foundation Power source Microphones Spectrum analyzer Stack of fuel cells
Power spectra and distribution of contrasts of natural images from different habitats
Grzywacz, Norberto
Power spectra and distribution of contrasts of natural images from different habitats Rosario M, atmospheric and underwater habitats were compared. For these habitats, we looked at two measures of the power spectrum and one of the distributions of contrasts. From power spectra, we analyzed the loglog slope
Narrowing of high power diode laser arrays using reflection feedback from an etalon
Romalis, Mike
Narrowing of high power diode laser arrays using reflection feedback from an etalon M. V. Romalisa for publication 27 June 2000 The spectrum of a high power multielement laser array is narrowed using reflection of the laser array is reduced by a factor of 2 with only 6% power loss. This reduction in FWHM is useful
Bimetric gravity and dark matter
Laura Bernard; Luc Blanchet; Lavinia Heisenberg
2015-07-10
We review some recent proposals for relativistic models of dark matter in the context of bimetric gravity. The aim is to solve the problems of cold dark matter (CDM) at galactic scales, and to reproduce the phenomenology of the modified Newtonian dynamics (MOND), while still being in agreement with the standard cosmological model $\\Lambda$-CDM at large scales. In this context a promising alternative is dipolar dark matter (DDM) in which two different species of dark matter particles are separately coupled to the two metrics of bigravity and are linked together by an internal vector field. The phenomenology of MOND then results from a mechanism of gravitational polarization. Probably the best formulation of the model is within the framework of recently developed massive bigravity theories. Then the gravitational sector of the model is safe by construction, but a ghostly degree of freedom in the decoupling limit is still present in the dark matter sector. Future work should analyse the cosmological solutions of the model and check the post-Newtonian parameters in the solar system.
None
2014-11-18
The U.S. Department of Energy's Princeton Plasma Physics Laboratory has released ''Star Power,'' a new informational video that uses dramatic and beautiful images and thought-provoking interviews to highlight the importance of the Laboratory's research into magnetic fusion.
2014-10-17
The U.S. Department of Energy's Princeton Plasma Physics Laboratory has released ''Star Power,'' a new informational video that uses dramatic and beautiful images and thought-provoking interviews to highlight the importance of the Laboratory's research into magnetic fusion.
Moments of $\\phi$ meson spectral functions in vacuum and nuclear matter
Gubler, Philipp
2015-01-01
Moments of the $\\phi$ meson spectral function in vacuum and in nuclear matter are analyzed, combining a model based on chiral SU(3) effective field theory (with kaonic degrees of freedom) and finite-energy QCD sum rules. For the vacuum we show that the spectral density is strongly constrained by a recent accurate measurement of the $e^+ e^- \\to K^+ K^-$ cross section. In nuclear matter the $\\phi$ spectrum is modified by interactions of the decay kaons with the surrounding nuclear medium, leading to a significant broadening and an asymmetric deformation of the $\\phi$ meson peak. We demonstrate that both in vacuum and nuclear matter, the first two moments of the spectral function are compatible with finite-energy QCD sum rules. A brief discussion of the next-higher spectral moment involving strange four-quark condensates is also presented.
Constraints on decaying dark matter from Fermi observations of nearby galaxies and clusters
Dugger, Leanna; Profumo, Stefano [Department of Astronomy and Department of Physics, University of California Berkeley, 601 Campbell Hall, Berkeley, CA (United States); Jeltema, Tesla E., E-mail: greentee01@gmail.com, E-mail: tesla@ucolick.org, E-mail: profumo@scipp.ucsc.edu [UCO/Lick Observatories, 1156 High St., Santa Cruz, CA 95064 (United States)
2010-12-01
We analyze the impact of Fermi gamma-ray observations (primarily non-detections) of selected nearby galaxies, including dwarf spheroidals, and of clusters of galaxies on decaying dark matter models. We show that the fact that galaxy clusters do not shine in gamma rays puts the most stringent limits available to-date on the lifetime of dark matter particles for a wide range of particle masses and decay final states. In particular, our results put strong constraints on the possibility of ascribing to decaying dark matter both the increasing positron fraction reported by PAMELA and the high-energy feature in the electron-positron spectrum measured by Fermi. Observations of nearby dwarf galaxies and of the Andromeda Galaxy (M31) do not provide as strong limits as those from galaxy clusters, while still improving on previous constraints in some cases.
The DAMIC dark matter experiment
Aguilar-Arevalo, A; Bertou, X; Bole, D; Butner, M; Cancelo, G; Vázquez, A Castańeda; Chavarria, A E; Neto, J R T de Mello; Dixon, S; D'Olivo, J C; Estrada, J; Moroni, G Fernandez; Torres, K P Hernández; Izraelevitch, F; Kavner, A; Kilminster, B; Lawson, I; Liao, J; López, M; Molina, J; Moreno-Granados, G; Pena, J; Privitera, P; Sarkis, Y; Scarpine, V; Schwarz, T; Haro, M Sofo; Tiffenberg, J; Machado, D Torres; Trillaud, F; You, X; Zhou, J
2015-01-01
The DAMIC (Dark Matter in CCDs) experiment uses high resistivity, scientific grade CCDs to search for dark matter. The CCD's low electronic noise allows an unprecedently low energy threshold of a few tens of eV that make it possible to detect silicon recoils resulting from interactions of low mass WIMPs. In addition the CCD's high spatial resolution and the excellent energy response results in very effective background identification techniques. The experiment has a unique sensitivity to dark matter particles with masses below 10 GeV/c$^2$. Previous results have demonstrated the potential of this technology, motivating the construction of DAMIC100, a 100 grams silicon target detector currently being installed at SNOLAB. In this contribution, the mode of operation and unique imaging capabilities of the CCDs, and how they may be exploited to characterize and suppress backgrounds will be discussed, as well as physics results after one year of data taking.
Alves, Daniele S.M.; Hedri, Sonia El; Wacker, Jay G.
2012-04-01
We discuss the relevance of directional detection experiments in the post-discovery era and propose a method to extract the local dark matter phase space distribution from directional data. The first feature of this method is a parameterization of the dark matter distribution function in terms of integrals of motion, which can be analytically extended to infer properties of the global distribution if certain equilibrium conditions hold. The second feature of our method is a decomposition of the distribution function in moments of a model independent basis, with minimal reliance on the ansatz for its functional form. We illustrate our method using the Via Lactea II N-body simulation as well as an analytical model for the dark matter halo. We conclude that O(1000) events are necessary to measure deviations from the Standard Halo Model and constrain or measure the presence of anisotropies.
Static Response of Neutron Matter
Buraczynski, Mateusz
2015-01-01
We generalize the problem of strongly interacting neutron matter by adding a periodic external modulation. This allows us to study from first principles a neutron system that is extended and inhomogeneous, with connections to the physics of both neutron-star crusts and neutron-rich nuclei. We carry out fully non-perturbative microscopic Quantum Monte Carlo calculations of the energy of neutron matter at different densities, as well as different strengths and periodicities of the external potential. In order to remove systematic errors, we examine finite-size effects and the impact of the wave function ansatz. We also make contact with energy-density functional theories of nuclei and disentangle isovector gradient contributions from bulk properties. Finally, we calculate the static density-density linear response function of neutron matter and compare it with the response of other physical systems.
Chiral condensate in neutron matter
N. Kaiser; W. Weise
2008-08-06
A recent chiral perturbation theory calculation of the in-medium quark condensate $$ is extended to the isospin-asymmetric case of pure neutron matter. In contrast to the behavior in isospin-symmetric nuclear matter we find only small deviations from the linear density approximation. This feature originates primarily from the reduced weight factors (e.g. 1/6 for the dominant contributions) of the $2\\pi$-exchange mechanisms in pure neutron matter. Our result suggests therefore that the tendencies for chiral symmetry restoration are actually favored in systems with large neutron excess (e.g. neutron stars). We also analyze the behavior of the density-dependent quark condensate $(\\rho_n)$ in the chiral limit $m_\\pi\\to 0$.
Matching Hagedorn mass spectrum with Lattice QCD
Lo, Pok Man; Redlich, Krzysztof; Sasaki, Chihiro
2015-01-01
Based on recent Lattice QCD (LQCD) results obtained at finite temperature, we discuss modeling of the hadronic phase of QCD in the framework of Hadron Resonance Gas (HRG) with discrete and continuous mass spectra. We focus on fluctuations of conserved charges, and show how a common limiting temperature can be used to constrain the Hagedorn exponential mass spectrum in different sectors of quantum number, through a matching of HRG and LQCD. For strange baryons, the extracted spectra are found to be consistent with all known and expected states listed by the Particle Data Group (PDG). The strange-mesonic sector, however, requires additional states in the intermediate mass range beyond that embodied in the database.
Matching Hagedorn mass spectrum with Lattice QCD
Pok Man Lo; Micha? Marczenko; Krzysztof Redlich; Chihiro Sasaki
2015-07-23
Based on recent Lattice QCD (LQCD) results obtained at finite temperature, we discuss modeling of the hadronic phase of QCD in the framework of Hadron Resonance Gas (HRG) with discrete and continuous mass spectra. We focus on fluctuations of conserved charges, and show how a common limiting temperature can be used to constrain the Hagedorn exponential mass spectrum in different sectors of quantum number, through a matching of HRG and LQCD. For strange baryons, the extracted spectra are found to be consistent with all known and expected states listed by the Particle Data Group (PDG). The strange-mesonic sector, however, requires additional states in the intermediate mass range beyond that embodied in the database.
Symmetry and Dirac points in graphene spectrum
Gregory Berkolaiko; Andrew Comech
2015-04-23
Existence and stability of Dirac points in the dispersion relation of operators periodic with respect to the hexagonal lattice is investigated for different sets of additional symmetries. The following symmetries are considered: rotation by $2\\pi/3$ and inversion, rotation by $2\\pi/3$ and horizontal reflection, inversion or reflection with weakly broken rotation symmetry, and the case where no Dirac points arise: rotation by $2\\pi/3$ and vertical reflection. All proofs are based on symmetry considerations and are elementary in nature. In particular, existence of degeneracies in the spectrum is proved by a transplantation argument (which is deduced from the (co)representation of the relevant symmetry group). The conical shape of the dispersion relation is obtained from its invariance under rotation by $2\\pi/3$. Persistence of conical points when the rotation symmetry is weakly broken is proved using a geometric phase in one case and parity of the eigenfunctions in the other.
THE FIRST H-BAND SPECTRUM OF THE GIANT PLANET ? PICTORIS b
Chilcote, Jeffrey; Fitzgerald, Michael P.; Larkin, James E.; Barman, Travis; Graham, James R.; Kalas, Paul; Macintosh, Bruce; Ingraham, Patrick; Bauman, Brian; Burrows, Adam S.; Cardwell, Andrew; Hartung, Markus; Hibon, Pascale; De Rosa, Robert J.; Dillon, Daren; Gavel, Donald; Dunn, Jennifer; Erikson, Darren; Goodsell, Stephen J.; and others
2015-01-01
Using the recently installed Gemini Planet Imager (GPI), we have obtained the first H-band spectrum of the planetary companion to the nearby young star ? Pictoris. GPI is designed to image and provide low-resolution spectra of Jupiter-sized, self-luminous planetary companions around young nearby stars. These observations were taken covering the H band (1.65 ?m). The spectrum has a resolving power of ?45 and demonstrates the distinctive triangular shape of a cool substellar object with low surface gravity. Using atmospheric models, we find an effective temperature of 1600-1700 K and a surface gravity of log (g) = 3.5-4.5 (cgs units). These values agree well with ''hot-start'' predictions from planetary evolution models for a gas giant with mass between 10 and 12 M {sub Jup} and age between 10 and 20 Myr.
Williams, Christopher Leigh
2012-01-01
The Murchison Widefield Array (MWA) is a new low-frequency radio array under construction in Western Australia with a primary goal of measuring the power spectrum of the 21-cm signal from neutral hydrogen during the Epoch ...
Power superconducting power transmission cable
Ashworth, Stephen P. (Cambridge, GB)
2003-01-01
The present invention is for a compact superconducting power transmission cable operating at distribution level voltages. The superconducting cable is a conductor with a number of tapes assembled into a subconductor. These conductors are then mounted co-planarly in an elongated dielectric to produce a 3-phase cable. The arrangement increases the magnetic field parallel to the tapes thereby reducing ac losses.
How to produce a reactor neutron spectrum using a proton accelerator
Burns, Kimberly A.; Wootan, David W.; Gates, Robert O.; Schmitt, Bruce E.; Asner, David M.
2015-01-01
A method for reproducing the neutron energy spectrum present in the core of an operating nuclear reactor using an engineered target in an accelerator proton beam is proposed. The protons interact with a target to create neutrons through various (p,n) type reactions. Spectral tailoring of the emitted neutrons can be used to modify the energy of the generated neutron spectrum to represent various reactor spectra. Through the use of moderators and reflectors, the neutron spectrum can be modified to reproduce many different spectra of interest including spectra in small thermal test reactors, large pressurized water reactors, and fast reactors. The particular application of this methodology is the design of an experimental approach for using an accelerator to measure the betas produced during fission to be used to reduce uncertainties in the interpretation of reactor antineutrino measurements. This approach involves using a proton accelerator to produce a neutron field representative of a power reactor, and using this neutron field to irradiate fission foils of the primary isotopes contributing to fission in the reactor, creating unstable, neutron rich fission products that subsequently beta decay and emit electron antineutrinos. A major advantage of an accelerator neutron source over a neutron beam from a thermal reactor is that the fast neutrons can be slowed down or tailored to approximate various power reactor spectra. An accelerator based neutron source that can be tailored to match various reactor neutron spectra provides an advantage for control in studying how changes in the neutron spectra affect parameters such as the resulting fission product beta spectrum.
Strong ''Quantum'' Chaos in the Global Ballooning Mode Spectrum...
Office of Scientific and Technical Information (OSTI)
formalism a chaotic Hamiltonian billiard problem. The minimum width of the toroidal Fourier spectrum needed for resolving toroidally localized ballooning modes with a global...
Pump Systems Matter Mission and Vision | Department of Energy
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
ionofPumpSystemsMatter.pdf More Documents & Publications Overview of Pump Systems Matter Hydraulic Institute Mission and Vision Course Overview Pump Systems Matter Optimization...
Why Geology Matters: Decoding the Past, Anticipating the Future
Anderson, Byron P.
2011-01-01
Review: Why Geology Matters: Decoding the Past, AnticipatingUSA Macdougall, Doug. Why Geology Matters: Decoding theE-book available. Why Geology Matters pursues two goals: to
Apparatus for particulate matter analysis
Gundel, Lara A.; Apte, Michael G.; Hansen, Anthony D.; Black, Douglas R.
2007-01-30
The apparatus described herein is a miniaturized system for particle exposure assessment (MSPEA) for the quantitative measurement and qualitative identification of particulate content in gases. The present invention utilizes a quartz crystal microbalance (QCM) or other mass-sensitive temperature compensated acoustic wave resonator for mass measurement. Detectors and probes and light sources are used in combination for the qualitative determination of particulate matter.
Laser Cooling of Matter INTRODUCTION
Kaiser, Robin
Laser Cooling of Matter INTRODUCTION Laser cooling of neutral atoms in the past decades has been a breakthrough in the understanding of their dy- namics and led to the seminal proposals of laser cooling-Doppler and subrecoil cooling, as well as new technologies, such as semiconductor diode lasers. Most of those
Udgaonkar, Jayant B.
- logical classification of different animal species) or some mixture of these (e.g. books in a library answer in this case is that states of matter is a classification scheme, like filing cabinets classification schemes could be alphabetical (e.g. in a dictionary), or based on some common properties ( zoo
Cohen, Timothy; Lisanti, Mariangela; Pierce, Aaron; Slatyer, Tracy R. E-mail: mlisanti@princeton.edu E-mail: tslatyer@mit.edu
2013-10-01
A fermion triplet of SU(2){sub L} — a wino — is a well-motivated dark matter candidate. This work shows that present-day wino annihilations are constrained by indirect detection experiments, with the strongest limits coming from H.E.S.S. and Fermi. The bounds on wino dark matter are presented as a function of mass for two scenarios: thermal (winos constitute a subdominant component of the dark matter for masses less than 3.1 TeV) and non-thermal (winos comprise all the dark matter). Assuming the NFW halo model, the H.E.S.S. search for gamma-ray lines excludes the 3.1 TeV thermal wino; the combined H.E.S.S. and Fermi results completely exclude the non-thermal scenario. Uncertainties in the exclusions are explored. Indirect detection may provide the only probe for models of anomaly plus gravity mediation where the wino is the lightest superpartner and scalars reside at the 100 TeV scale.
Solar Neutrino Matter Effects Redux
A. B. Balantekin; A. Malkus
2011-12-19
Following recent low-threshold analysis of the Sudbury Neutrino Observatory and asymmetry measurements of the BOREXINO Collaboration of the solar neutrino flux, we revisit the analysis of the matter effects in the Sun. We show that solar neutrino data constrains the mixing angle $\\theta_{13}$ poorly and that subdominant Standard Model effects can mimic the effects of the physics beyond the Standard Model.
David O. Caldwell
1998-12-01
Despite direct observations favoring a low mass density, a critical density universe with a neutrino component of dark matter provides the best existing model to explain the observed structure of the universe over more than three orders of magnitude in distance scale. In principle this hot dark matter could consist of one, two, or three species of active neutrinos. If all present indications for neutrino mass are correct, however, only the two-species (muon neutrino and tau neutrino) possibility works. This requires the existence of at least one light sterile neutrino to explain the solar electron neutrino deficit via nu(e)->nu(s), leaving nu(mu)->nu(tau) as the explanation for the anomalous nu(mu)/nu(e) ratio produced by atmospheric neutrinos, and having the LSND experiment demonstrating via anti-nu(mu)-> anti-nu(e) the mass difference between the light nu(e)-nu(s) pair and the heavier nu(mu)-nu(tau) pair required for dark matter. Other experiments do not conflict with the LSND results when all the experiments are analyzed in the same way, and when analyzed conservatively the LSND data is quite compatible with the mass difference needed for dark matter. Further support for this mass pattern is provided by the need for a sterile neutrino to rescue heavy-element nucleosynthesis in supernovae, and it could even aid the concordance in light element abundances from the early universe.
Gehman, V M; Rielage, K; Hime, A; Sun, Y; Mei, D -M; Maassen, J; Moore, D
2011-01-01
A large number of current and future experiments in neutrino and dark matter detection use the scintillation light from noble elements as a mechanism for measuring energy deposition. The scintillation light from these elements is produced in the extreme ultraviolet (EUV) range, from 60 - 200 nm. Currently, the most practical technique for observing light at these wavelengths is to surround the scintillation volume with a thin film of Tetraphenyl Butadiene (TPB) to act as a fluor. The TPB film absorbs EUV photons and reemits visible photons, detectable with a variety of commercial photosensors. Here we present a measurement of the re-emission spectrum of TPB films when illuminated with 128, 160, 175, and 250 nm light. We also measure the fluorescence efficiency as a function of incident wavelength from 120 to 250 nm.
V. M. Gehman; S. R. Seibert; K. Rielage; A. Hime; Y. Sun; D. -M. Mei; J. Maassen; D. Moore
2011-09-22
A large number of current and future experiments in neutrino and dark matter detection use the scintillation light from noble elements as a mechanism for measuring energy deposition. The scintillation light from these elements is produced in the extreme ultraviolet (EUV) range, from 60 - 200 nm. Currently, the most practical technique for observing light at these wavelengths is to surround the scintillation volume with a thin film of Tetraphenyl Butadiene (TPB) to act as a fluor. The TPB film absorbs EUV photons and reemits visible photons, detectable with a variety of commercial photosensors. Here we present a measurement of the re-emission spectrum of TPB films when illuminated with 128, 160, 175, and 250 nm light. We also measure the fluorescence efficiency as a function of incident wavelength from 120 to 250 nm.