National Library of Energy BETA

Sample records for bispectral threshold method

  1. Methods for automatic trigger threshold adjustment

    DOE Patents [OSTI]

    Welch, Benjamin J; Partridge, Michael E

    2014-03-18

    Methods are presented for adjusting trigger threshold values to compensate for drift in the quiescent level of a signal monitored for initiating a data recording event, thereby avoiding false triggering conditions. Initial threshold values are periodically adjusted by re-measuring the quiescent signal level, and adjusting the threshold values by an offset computation based upon the measured quiescent signal level drift. Re-computation of the trigger threshold values can be implemented on time based or counter based criteria. Additionally, a qualification width counter can be utilized to implement a requirement that a trigger threshold criterion be met a given number of times prior to initiating a data recording event, further reducing the possibility of a false triggering situation.

  2. Methods for threshold determination in multiplexed assays

    DOE Patents [OSTI]

    Tammero, Lance F. Bentley; Dzenitis, John M; Hindson, Benjamin J

    2014-06-24

    Methods for determination of threshold values of signatures comprised in an assay are described. Each signature enables detection of a target. The methods determine a probability density function of negative samples and a corresponding false positive rate curve. A false positive criterion is established and a threshold for that signature is determined as a point at which the false positive rate curve intersects the false positive criterion. A method for quantitative analysis and interpretation of assay results together with a method for determination of a desired limit of detection of a signature in an assay are also described.

  3. ARM - VAP Process - lbtm-minnis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    : Layered Bispectral Threshold Method (LBTM) cloud products derived from GMS-5,Darwin lbtm3minnisman : Layered Bispectral Threshold Method (LBTM) cloud products derived...

  4. Threshold selection for classification of MR brain images by clustering method

    SciTech Connect (OSTI)

    Moldovanu, Simona; Obreja, Cristian; Moraru, Luminita

    2015-12-07

    Given a grey-intensity image, our method detects the optimal threshold for a suitable binarization of MR brain images. In MR brain image processing, the grey levels of pixels belonging to the object are not substantially different from the grey levels belonging to the background. Threshold optimization is an effective tool to separate objects from the background and further, in classification applications. This paper gives a detailed investigation on the selection of thresholds. Our method does not use the well-known method for binarization. Instead, we perform a simple threshold optimization which, in turn, will allow the best classification of the analyzed images into healthy and multiple sclerosis disease. The dissimilarity (or the distance between classes) has been established using the clustering method based on dendrograms. We tested our method using two classes of images: the first consists of 20 T2-weighted and 20 proton density PD-weighted scans from two healthy subjects and from two patients with multiple sclerosis. For each image and for each threshold, the number of the white pixels (or the area of white objects in binary image) has been determined. These pixel numbers represent the objects in clustering operation. The following optimum threshold values are obtained, T = 80 for PD images and T = 30 for T2w images. Each mentioned threshold separate clearly the clusters that belonging of the studied groups, healthy patient and multiple sclerosis disease.

  5. Organic thin film devices with stabilized threshold voltage and mobility, and method for preparing the devices

    DOE Patents [OSTI]

    Nastasi, Michael Anthony; Wang, Yongqiang; Fraboni, Beatrice; Cosseddu, Piero; Bonfiglio, Annalisa

    2013-06-11

    Organic thin film devices that included an organic thin film subjected to a selected dose of a selected energy of ions exhibited a stabilized mobility (.mu.) and threshold voltage (VT), a decrease in contact resistance R.sub.C, and an extended operational lifetime that did not degrade after 2000 hours of operation in the air.

  6. Adaptive Thresholds

    Energy Science and Technology Software Center (OSTI)

    2014-08-26

    ADAPT is a topological analysis code that allow to compute local threshold, in particular relevance based thresholds for features defined in scalar fields. The initial target application is vortex detection but the software is more generally applicable to all threshold based feature definitions.

  7. FAR Dollar Threshold Changes

    Broader source: Energy.gov [DOE]

    Attached is a table summarizing the new FAR dollar thresholds. These thresholds became effective on October 1, 2010.

  8. Threshold Reflectivity Zc

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    The black and red colors represent those for 0.33 (q 3) and 1(q 1), respectively. The dependency exhibits two distinct regimes: threshold function ...

  9. ARM - Publications: Science Team Meeting Documents

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    GOES-8 cloud and radiative properties data set. The ARM GOES-8 data set is derived using the Layered Bispectral Threshold Method (LBTM, see Khaiyer et al., 2001 this conference). ...

  10. ARM - VAP Product - lbtm3minnisdar

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    below or call us at 1-888-ARM-DATA. Send VAP Output : LBTM3MINNISDAR Layered Bispectral Threshold Method (LBTM) cloud products derived from GMS-5,Darwin Active Dates 2002.04.01...

  11. Hydrogen Threshold Cost Calculation

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Program Record (Offices of Fuel Cell Technologies) Record #: 11007 Date: March 25, 2011 Title: Hydrogen Threshold Cost Calculation Originator: Mark Ruth & Fred Joseck Approved by: Sunita Satyapal Date: March 24, 2011 Description: The hydrogen threshold cost is defined as the hydrogen cost in the range of $2.00-$4.00/gge (2007$) which represents the cost at which hydrogen fuel cell electric vehicles (FCEVs) are projected to become competitive on a cost per mile basis with the competing

  12. Threshold electron excitation of Na

    SciTech Connect (OSTI)

    Marinkovic, B.; Wang, P.; Gallagher, A. )

    1992-09-01

    Electron collisional excitation of the 4{ital D}, 5{ital D}, 4{ital P}, and 6{ital S} states of Na has been measured with about 30-meV energy resolution. Very rapid, unresolved threshold onsets are seen for all but the 4{ital P} state, and a near-threshold resonance is suggested by the 5{ital D} data. However, only weak undulations in the cross sections are observed above threshold.

  13. Probabilistic Threshold Criterion

    SciTech Connect (OSTI)

    Gresshoff, M; Hrousis, C A

    2010-03-09

    The Probabilistic Shock Threshold Criterion (PSTC) Project at LLNL develops phenomenological criteria for estimating safety or performance margin on high explosive (HE) initiation in the shock initiation regime, creating tools for safety assessment and design of initiation systems and HE trains in general. Until recently, there has been little foundation for probabilistic assessment of HE initiation scenarios. This work attempts to use probabilistic information that is available from both historic and ongoing tests to develop a basis for such assessment. Current PSTC approaches start with the functional form of the James Initiation Criterion as a backbone, and generalize to include varying areas of initiation and provide a probabilistic response based on test data for 1.8 g/cc (Ultrafine) 1,3,5-triamino-2,4,6-trinitrobenzene (TATB) and LX-17 (92.5% TATB, 7.5% Kel-F 800 binder). Application of the PSTC methodology is presented investigating the safety and performance of a flying plate detonator and the margin of an Ultrafine TATB booster initiating LX-17.

  14. Effects of pulse duration on magnetostimulation thresholds

    SciTech Connect (OSTI)

    Saritas, Emine U.; Goodwill, Patrick W.; Conolly, Steven M.

    2015-06-15

    Purpose: Medical imaging techniques such as magnetic resonance imaging and magnetic particle imaging (MPI) utilize time-varying magnetic fields that are subject to magnetostimulation limits, which often limit the speed of the imaging process. Various human-subject experiments have studied the amplitude and frequency dependence of these thresholds for gradient or homogeneous magnetic fields. Another contributing factor was shown to be number of cycles in a magnetic pulse, where the thresholds decreased with longer pulses. The latter result was demonstrated on two subjects only, at a single frequency of 1.27 kHz. Hence, whether the observed effect was due to the number of cycles or due to the pulse duration was not specified. In addition, a gradient-type field was utilized; hence, whether the same phenomenon applies to homogeneous magnetic fields remained unknown. Here, the authors investigate the pulse duration dependence of magnetostimulation limits for a 20-fold range of frequencies using homogeneous magnetic fields, such as the ones used for the drive field in MPI. Methods: Magnetostimulation thresholds were measured in the arms of six healthy subjects (age: 27 ± 5 yr). Each experiment comprised testing the thresholds at eight different pulse durations between 2 and 125 ms at a single frequency, which took approximately 30–40 min/subject. A total of 34 experiments were performed at three different frequencies: 1.2, 5.7, and 25.5 kHz. A solenoid coil providing homogeneous magnetic field was used to induce stimulation, and the field amplitude was measured in real time. A pre-emphasis based pulse shaping method was employed to accurately control the pulse durations. Subjects reported stimulation via a mouse click whenever they felt a twitching/tingling sensation. A sigmoid function was fitted to the subject responses to find the threshold at a specific frequency and duration, and the whole procedure was repeated at all relevant frequencies and pulse durations

  15. Measurement of the {sup 13}C(α,n){sup 16}O reaction with the Trojan horse method: Focus on the sub threshold resonance at −3 keV

    SciTech Connect (OSTI)

    La Cognata, M.; Spitaleri, C.; Guardo, G. L.; Puglia, S. M. R.; Romano, S.; Spartà, R.; Trippella, O.; Kiss, G. G.; Rogachev, G. V.; Avila, M.; Koshchiy, E.; Kuchera, A.; Santiago, D.; Mukhamedzhanov, A. M.; Lamia, L.

    2014-05-02

    The {sup 13}C(α,n){sup 16}O reaction is the neutron source of the main component of the s-process. The astrophysical S(E)-factor is dominated by the −3 keV sub-threshold resonance due to the 6.356 MeV level in {sup 17}O. Its contribution is still controversial as extrapolations, e.g., through R-matrix calculations, and indirect techniques, such as the asymptotic normalization coefficient (ANC), yield inconsistent results. Therefore, we have applied the Trojan Horse Method (THM) to the {sup 13}C({sup 6}Li,n{sup 16}O)d reaction to measure its contribution. For the first time, the ANC for the 6.356 MeV level has been deduced through the THM, allowing to attain an unprecedented accuracy. Though a larger ANC for the 6.356 MeV level is measured, our experimental S(E) factor agrees with the most recent extrapolation in the literature in the 140-230 keV energy interval, the accuracy being greatly enhanced thanks to this innovative approach, merging together two well establish indirect techniques, namely, the THM and the ANC.

  16. Hydrogen Threshold Cost Calculation | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Threshold Cost Calculation Hydrogen Threshold Cost Calculation DOE Hydrogen Program Record number11007, Hydrogen Threshold Cost Calculation, documents the methodology and assumptions used to calculate that threshold cost. 11007_h2_threshold_costs.pdf (443.22 KB) More Documents & Publications DOE Hydrogen and Fuel Cells Program Record 11007: Hydrogen Threshold Cost Calculation Fuel Cell Technologies Program Overview: 2010 Annual Merit Review and Peer Evaluation Meeting Fuel Cell Technologies

  17. GC GUIDANCE ON MINOR CONSTRUCTION THRESHOLDS

    Energy Savers [EERE]

    GUIDANCE ON MINOR CONSTRUCTION THRESHOLDS We have been asked about how the Department implements what is known as the "minor construction threshold," which limits the amount of ...

  18. Threshold 21 Model | Open Energy Information

    Open Energy Info (EERE)

    Moderate Website: www.millennium-institute.orgintegratedplanningtoolsT21 Cost: Free Threshold 21 Model Screenshot References: Threshold 21 Model1 Related Tools Energy...

  19. Compositional threshold for Nuclear Waste Glass Durability

    SciTech Connect (OSTI)

    Kruger, Albert A.; Farooqi, Rahmatullah; Hrma, Pavel R.

    2013-04-24

    Within the composition space of glasses, a distinct threshold appears to exist that separates "good" glasses, i.e., those which are sufficiently durable, from "bad" glasses of a low durability. The objective of our research is to clarify the origin of this threshold by exploring the relationship between glass composition, glass structure and chemical durability around the threshold region.

  20. DOE Hydrogen and Fuel Cells Program Record 11007: Hydrogen Threshold...

    Office of Environmental Management (EM)

    1007: Hydrogen Threshold Cost Calculation DOE Hydrogen and Fuel Cells Program Record 11007: Hydrogen Threshold Cost Calculation The hydrogen threshold cost is defined as the ...

  1. Acquisition Guide Chapter Updates for Threshold Changes

    Broader source: Energy.gov [DOE]

    The Federal Acquisition Regulation is regularly updated to revise dollar thresholds associated for various activities. Policy Flash 2011-15 provides a quick reference guide to the threshold changes that were effective October 1, 2010. This Flash is to inform you that the following Guide Chapters have been updated to reflect the threshold changes: Chapter 3.1 Chapter 6.1 Chapter 15.4-4 Chapter 16.1 Chapter 18.0 Chapter 37.1 Chapter 38.1

  2. CABLE TECHNOLOGY LABORATORIES, INC. DETERMINATION OF THRESHOLD...

    Office of Scientific and Technical Information (OSTI)

    Cable TABLE OF CONTENTS ABSTRACT INTRODUCTION DESCRIPTION OF TEST CABLES TEMPERATURE CONDITIONING OF TEST CABLES TESTING OF XLPE INSULATED CABLE BEFORE AGING Threshold ...

  3. DOE Contractor Work Force Restructuring Approval Thresholds

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Contractor Work Force Restructuring Approval Thresholds Up to 100 employees Contractor can ... to provide approval for NNSA work force restructurings in consultation with LM 501 ...

  4. CABLE TECHNOLOGY LABORATORIES, INC. DETERMINATION OF THRESHOLD...

    Office of Scientific and Technical Information (OSTI)

    CABLE TECHNOLOGY LABORATORIES, INC. DETERMINATION OF THRESHOLD AND MAXIMUM OPERATING ELECTRIC STRESSES FOR SELECTED HIGH VOLTAGE INSULATIONS Investigation of Aged Polymeric ...

  5. New photodisintegration threshold observable in

    SciTech Connect (OSTI)

    E.A. Wulf; R.S. Canon; Sally J. Gaff; J.H. Kelley; R.M. Prior; E.C. Schreiber; M. Spraker; D.R. Tilley; H.R. Weller; M. Viviani; A. Kievsky; S. Rosati; Rocco Schiavilla

    2000-02-01

    Measurements of the cross section, vector, and tensor analyzing powers, and linear gamma-ray polarization in the radiative capture reactions D(p,y){sup 3} He and p(d,y){sup 3}He at c.m. energies in the range 0-53 keV allow the determination of the reduced matrix elements (RMEs) relevant for these transitions. From these RMEs the value of the integral which determines the Gerasimov-Drell-Hearn sum rule for He is obtained in the threshold region, corresponding to two-body breakup, and compared with the results of an ab initio microscopic three-body model calculation.The theoretical predictions for the value of this integral based on a ''nucleons-only'' assumption are an order of magnitude smaller than experiment. The discrepancy is reduced to about a factor of 2 when two-body currents are taken into account. This factor of 2 is due to an almost exact cancellation between the dominant E1 RMEs in the theoretical calculation. The excess E1 strength observed experimentally could provide useful insights into the nuclear interaction at low energies.

  6. Threshold magnitudes for a multichannel correlation detector in background seismicity

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Carmichael, Joshua D.; Hartse, Hans

    2016-04-01

    Colocated explosive sources often produce correlated seismic waveforms. Multichannel correlation detectors identify these signals by scanning template waveforms recorded from known reference events against "target" data to find similar waveforms. This screening problem is challenged at thresholds required to monitor smaller explosions, often because non-target signals falsely trigger such detectors. Therefore, it is generally unclear what thresholds will reliably identify a target explosion while screening non-target background seismicity. Here, we estimate threshold magnitudes for hypothetical explosions located at the North Korean nuclear test site over six months of 2010, by processing International Monitoring System (IMS) array data with a multichannelmore » waveform correlation detector. Our method (1) accounts for low amplitude background seismicity that falsely triggers correlation detectors but is unidentifiable with conventional power beams, (2) adapts to diurnally variable noise levels and (3) uses source-receiver reciprocity concepts to estimate thresholds for explosions spatially separated from the template source. Furthermore, we find that underground explosions with body wave magnitudes mb = 1.66 are detectable at the IMS array USRK with probability 0.99, when using template waveforms consisting only of P -waves, without false alarms. We conservatively find that these thresholds also increase by up to a magnitude unit for sources located 4 km or more from the Feb.12, 2013 announced nuclear test.« less

  7. ARM - VAP Product - lbtm3minnisman

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    minnisman Documentation lbtm-minnis : XDC documentation Data Management Facility Plots (Quick Looks) ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send VAP Output : LBTM3MINNISMAN Layered Bispectral Threshold Method (LBTM) cloud products derived from GMS-5,Manus

  8. ARM - VAP Product - lbtm3minnisnau

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    minnisnau Documentation lbtm-minnis : XDC documentation Data Management Facility Plots (Quick Looks) ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send VAP Output : LBTM3MINNISNAU Layered Bispectral Threshold Method (LBTM) cloud products derived from GMS-5,Nauru

  9. Initiation Pressure Thresholds from Three Sources

    SciTech Connect (OSTI)

    Souers, P C; Vitello, P

    2007-02-28

    Pressure thresholds are minimum pressures needed to start explosive initiation that ends in detonation. We obtain pressure thresholds from three sources. Run-to-detonation times are the poorest source but the fitting of a function gives rough results. Flyer-induced initiation gives the best results because the initial conditions are the best known. However, very thick flyers are needed to give the lowest, asymptotic pressure thresholds used in modern models and this kind of data is rarely available. Gap test data is in much larger supply but the various test sizes and materials are confusing. We find that explosive pressures are almost the same if the distance in the gap test spacers are in units of donor explosive radius. Calculated half-width time pulses in the spacers may be used to create a pressure-time curve similar to that of the flyers. The very-large Eglin gap tests give asymptotic thresholds comparable to extrapolated flyer results. The three sources are assembled into a much-expanded set of near-asymptotic pressure thresholds. These thresholds vary greatly with density: for TATB/LX-17/PBX 9502, we find values of 4.9 and 8.7 GPa at 1.80 and 1.90 g/cm{sup 3}, respectively.

  10. THRESHOLD FOR EXTENDED EMISSION IN SHORT GAMMA-RAY BURSTS

    SciTech Connect (OSTI)

    Norris, Jay P.; Gehrels, Neil

    2010-07-01

    The initial pulse complex (IPC) in short gamma-ray bursts is sometimes accompanied by a softer, low-intensity extended emission (EE) component. In cases where such a component is not observed, it is not clear if it is present but below the detection threshold. Using Bayesian Block (BB) methods, we measure the EE component and show that it is present in one-quarter of a Swift/BAT sample of 51 short bursts, as was found for the Compton/BATSE sample. We simulate bursts with EE to calibrate the BAT threshold for EE detection and show that this component would have been detected in nearly half of BAT short bursts if it were present, to intensities {approx}10{sup -2} counts cm{sup -2} s{sup -1}, a factor of 5 lower than actually observed in short bursts. In the BAT sample, the ratio of average EE intensity to IPC peak intensity, R{sub int}, ranges over a factor of 25, R{sub int} {approx} 3 x 10{sup -3} to 8 x 10{sup -2}. In comparison, for the average of the 39 bursts without an EE component, the 2{sigma} upper limit is R{sub int} < 8 x 10{sup -4}. These results suggest that a physical threshold effect operates near R{sub int} {approx} few x 10{sup -3} below which the EE component is not manifest.

  11. Pressure Systems Stored-Energy Threshold Risk Analysis

    SciTech Connect (OSTI)

    Paulsen, Samuel S.

    2009-08-25

    Federal Regulation 10 CFR 851, which became effective February 2007, brought to light potential weaknesses regarding the Pressure Safety Program at the Pacific Northwest National Laboratory (PNNL). The definition of a pressure system in 10 CFR 851 does not contain a limit based upon pressure or any other criteria. Therefore, the need for a method to determine an appropriate risk-based hazard level for pressure safety was identified. The Laboratory has historically used a stored energy of 1000 lbf-ft to define a pressure hazard; however, an analytical basis for this value had not been documented. This document establishes the technical basis by evaluating the use of stored energy as an appropriate criterion to establish a pressure hazard, exploring a suitable risk threshold for pressure hazards, and reviewing the methods used to determine stored energy. The literature review and technical analysis concludes the use of stored energy as a method for determining a potential risk, the 1000 lbf-ft threshold, and the methods used by PNNL to calculate stored energy are all appropriate. Recommendations for further program improvements are also discussed

  12. Monolayer semiconductor nanocavity lasers with ultralow thresholds

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wu, Sanfeng; Buckley, Sonia; Schaibley, John R.; Feng, Liefeng; Yan, Jiaqiang; Mandrus, David G.; Hatami, Fariba; Yao, Wang; Vučković, Jelena; Majumdar, Arka; et al

    2015-03-16

    Engineering the electromagnetic environment of a nanoscale light emitter by a photonic cavity can significantly enhance its spontaneous emission rate through cavity quantum electrodynamics in the Purcell regime. This effect can greatly reduce the lasing threshold of the emitter1–5, providing the ultimate low-threshold laser system with small footprint, low power consumption and ultrafast modulation. A state-of-the-art ultra-low threshold nanolaser has been successfully developed though embedding quantum dots into photonic crystal cavity (PhCC)6–8. However, several core challenges impede the practical applications of this architecture, including the random positions and compositional fluctuations of the dots7, extreme difficulty in current injection8, and lackmore » of compatibility with electronic circuits7,8. Here, we report a new strategy to lase, where atomically thin crystalline semiconductor, i.e., a tungsten-diselenide (WSe2) monolayer, is nondestructively and deterministically introduced as a gain medium at the surface of a pre-fabricated PhCC. A new type of continuous-wave nanolaser operating in the visible regime is achieved with an optical pumping threshold as low as 27 nW at 130 K, similar to the value achieved in quantum dot PhCC lasers7. The key to the lasing action lies in the monolayer nature of the gain medium, which confines direct-gap excitons to within 1 nm of the PhCC surface. The surface-gain geometry allows unprecedented accessibilities to multi-functionalize the gain, enabling electrically pumped operation. Our scheme is scalable and compatible with integrated photonics for on-chip optical communication technologies.« less

  13. DOE Contractor Work Force Restructuring Approval Thresholds

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Contractor Work Force Restructuring Approval Thresholds Up to 100 employees Contractor can make decision bit must notify DOE of intent of restructuring 101-200 employees DOE/NNSA field office is authorized to provide approval 201-500 employees LM is authorized to provide approval and NNSA Administrator is authorized to provide approval for NNSA work force restructurings in consultation with LM 501 and above employees Under Secretary/NNSA Administrator approval required

  14. Acoustic emission sensor radiation damage threshold experiment

    SciTech Connect (OSTI)

    Beeson, K.M.; Pepper, C.E.

    1994-09-01

    Determination of the threshold for damage to acoustic emission sensors exposed to radiation is important in their application to leak detection in radioactive waste transport and storage. Proper response to system leaks is necessary to ensure the safe operation of these systems. A radiation impaired sensor could provide ``false negative or false positive`` indication of acoustic signals from leaks within the system. Research was carried out in the Radiochemical Technology Division at Oak Ridge National Laboratory to determine the beta/gamma radiation damage threshold for acoustic emission sensor systems. The individual system consisted of an acoustic sensor mounted with a two part epoxy onto a stainless steel waveguide. The systems were placed in an irradiation fixture and exposed to a Cobalt-60 source. After each irradiation, the sensors were recalibrated by Physical Acoustics Corporation. The results were compared to the initial calibrations performed prior to irradiation and a control group, not exposed to radiation, was used to validate the results. This experiment determines the radiation damage threshold of each acoustic sensor system and verifies its life expectancy, usefulness and reliability for many applications in radioactive environments.

  15. Threshold photodetachment spectroscopy of negative ions

    SciTech Connect (OSTI)

    Kitsopoulos, T.N.

    1991-12-01

    This thesis is concerned with the development and application of high resolution threshold photodetachment spectroscopy of negative ions. Chapter I deals with the principles of our photodetachment technique, and in chapter II a detailed description of the apparatus is presented. The threshold photodetachment spectra of I{sup {minus}}, and SH{sup {minus}}, presented in the last sections of chapter II, indicated that a resolution of 3 cm{sup {minus}1} can be achieved using our technique. In chapter III the threshold photodetachment spectroscopy study of the transition state region of I + HI and I + Di reactions is discussed. Our technique probes the transition state region directly, and the results of our study are the first unambiguous observations of reactive resonances in a chemical reaction. Chapters IV, V and VI are concerned with the spectroscopy of small silicon and carbon clusters. From our spectra we were able to assign electronic state energies and vibrational frequencies for the low lying electronics states of Si{sub n} (n=2,3,4), C{sub 5} and their corresponding anions.

  16. Category 3 threshold quantities for hazard categorization of nonreactor facilities

    SciTech Connect (OSTI)

    Mandigo, R.L.

    1996-02-13

    This document provides the information necessary to determine Hazard Category 3 threshold quantities for those isotopes of interest not listed in WHC-CM-4-46, Section 4, Table 1.''Threshold Quantities.''

  17. Ionization Thresholds of Small Carbon Clusters: Tunable VUVExperiments and Theory

    SciTech Connect (OSTI)

    Belau, Leonid; Wheeler, Steven E.; Ticknor, Brian W.; Ahmed,Musahid; Leone, Stephen R.; Allen, Wesley D.; Schaefer III, Henry F.; Duncan, Michael A.

    2007-07-31

    Small carbon clusters (Cn, n = 2-15) are produced in amolecular beam by pulsed laser vaporization and studied with vacuumultraviolet (VUV) photoionization mass spectrometry. The required VUVradiation in the 8-12 eV range is provided by the Advanced Light Source(ALS) at the Lawrence Berkeley National Laboratory. Mass spectra atvarious ionization energies reveal the qualitative relative abundances ofthe neutral carbon clusters produced. By far the most abundant species isC3. Using the tunability of the ALS, ionization threshold spectra arerecorded for the clusters up to 15 atoms in size. The ionizationthresholds are compared to those measured previously with charge-transferbracketing methods. To interpret the ionization thresholds for differentcluster sizes, new ab initio calculations are carried out on the clustersfor n = 4-10. Geometric structures are optimized at the CCSD(T) levelwith cc-pVTZ (or cc-pVDZ) basis sets, and focal point extrapolations areapplied to both neutral and cation species to determine adiabatic andvertical ionization potentials. The comparison of computed and measuredionization potentials makes it possible to investigate the isomericstructures of the neutral clusters produced in this experiment. Themeasurements are inconclusive for the n = 4-6 species because ofunquenched excited electronic states. However, the data provide evidencefor the prominence of linear structures for the n = 7, 9, 11, 13 speciesand the presence of cyclic C10.

  18. Threshold Phenomena in a Throbbing Complex Plasma

    SciTech Connect (OSTI)

    Mikikian, Maxime; Coueedel, Lenaiec; Cavarroc, Marjorie; Tessier, Yves; Boufendi, Laiefa

    2010-08-13

    In complex plasmas, the trapped dust particle cloud is often characterized by a central dust-free region ('void'). The void induces a spatial inhomogeneity of the dust particle distribution and is at the origin of many intricate unstable phenomena. One type of this kind of behavior is the so-called heartbeat instability consisting of successive contractions and expansions of the void. This instability is characterized by a strong nonlinear dynamics which can reveal the occurrence of incomplete sequences corresponding to failed contractions. Experimental results based on high-speed imaging are presented for the first time and underline this threshold effect in both the dust cloud motion and the evolution of the plasma light emission.

  19. Optical ranked-order filtering using threshold decomposition

    DOE Patents [OSTI]

    Allebach, Jan P.; Ochoa, Ellen; Sweeney, Donald W.

    1990-01-01

    A hybrid optical/electronic system performs median filtering and related ranked-order operations using threshold decomposition to encode the image. Threshold decomposition transforms the nonlinear neighborhood ranking operation into a linear space-invariant filtering step followed by a point-to-point threshold comparison step. Spatial multiplexing allows parallel processing of all the threshold components as well as recombination by a second linear, space-invariant filtering step. An incoherent optical correlation system performs the linear filtering, using a magneto-optic spatial light modulator as the input device and a computer-generated hologram in the filter plane. Thresholding is done electronically. By adjusting the value of the threshold, the same architecture is used to perform median, minimum, and maximum filtering of images. A totally optical system is also disclosed.

  20. Optical ranked-order filtering using threshold decomposition

    DOE Patents [OSTI]

    Allebach, J.P.; Ochoa, E.; Sweeney, D.W.

    1987-10-09

    A hybrid optical/electronic system performs median filtering and related ranked-order operations using threshold decomposition to encode the image. Threshold decomposition transforms the nonlinear neighborhood ranking operation into a linear space-invariant filtering step followed by a point-to-point threshold comparison step. Spatial multiplexing allows parallel processing of all the threshold components as well as recombination by a second linear, space-invariant filtering step. An incoherent optical correlation system performs the linear filtering, using a magneto-optic spatial light modulator as the input device and a computer-generated hologram in the filter plane. Thresholding is done electronically. By adjusting the value of the threshold, the same architecture is used to perform median, minimum, and maximum filtering of images. A totally optical system is also disclosed. 3 figs.

  1. Threshold Values for Identification of Contamination Predicted by Reduced-Order Models

    SciTech Connect (OSTI)

    Last, George V.; Murray, Christopher J.; Bott, Yi-Ju; Brown, Christopher F.

    2014-12-31

    The U.S. Department of Energys (DOEs) National Risk Assessment Partnership (NRAP) Project is developing reduced-order models to evaluate potential impacts on underground sources of drinking water (USDWs) if CO2 or brine leaks from deep CO2 storage reservoirs. Threshold values, below which there would be no predicted impacts, were determined for portions of two aquifer systems. These threshold values were calculated using an interwell approach for determining background groundwater concentrations that is an adaptation of methods described in the U.S. Environmental Protection Agencys Unified Guidance for Statistical Analysis of Groundwater Monitoring Data at RCRA Facilities.

  2. Threshold Values for Identification of Contamination Predicted by Reduced-Order Models

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Last, George V.; Murray, Christopher J.; Bott, Yi-Ju; Brown, Christopher F.

    2014-12-31

    The U.S. Department of Energy’s (DOE’s) National Risk Assessment Partnership (NRAP) Project is developing reduced-order models to evaluate potential impacts on underground sources of drinking water (USDWs) if CO2 or brine leaks from deep CO2 storage reservoirs. Threshold values, below which there would be no predicted impacts, were determined for portions of two aquifer systems. These threshold values were calculated using an interwell approach for determining background groundwater concentrations that is an adaptation of methods described in the U.S. Environmental Protection Agency’s Unified Guidance for Statistical Analysis of Groundwater Monitoring Data at RCRA Facilities.

  3. Probabilistic Shock Iinitiation Thresholds and QMU Applications

    SciTech Connect (OSTI)

    Hrousis, C A; Gresshoff, M; Overturf, G E

    2009-04-10

    The Probabilistic Threshold Criterion (PTC) Project at LLNL develops phenomenological criteria for establishing margin of safety or performance margin on high explosive (HE) initiation in the high-speed impact regime, creating tools for safety assessment and design of initiation systems and HE trains in general. Until recently, there has been little foundation for probabilistic assessment of HE initiation scenarios. This work attempts to use probabilistic information that is available from both historic and ongoing tests to develop a basis for such assessment. Current PTC approaches start with the functional form of James Initiation Criterion as a backbone, and generalize to include varying areas of initiation and provide a probabilistic response based on test data. Recent work includes application of the PTC methodology to safety assessments involving a donor charge detonation and the need for assessment of a nearby acceptor charge's response, as well as flyer-acceptor configurations, with and without barriers. Results to date are in agreement with other less formal assessment protocols, and indicate a promising use for PTC-based assessments. In particular, there is interest in this approach because it supports the Quantified Margins and Uncertainties (QMU) framework for establishing confidence in the performance and/or safety of an HE system.

  4. Measurement and interpretation of threshold stress intensity factors for steels in high-pressure hydrogen gas.

    SciTech Connect (OSTI)

    Dadfarnia, Mohsen; Nibur, Kevin A.; San Marchi, Christopher W.; Sofronis, Petros; Somerday, Brian P.; Foulk, James W., III; Hayden, Gary A.

    2010-07-01

    Threshold stress intensity factors were measured in high-pressure hydrogen gas for a variety of low alloy ferritic steels using both constant crack opening displacement and rising crack opening displacement procedures. The sustained load cracking procedures are generally consistent with those in ASME Article KD-10 of Section VIII Division 3 of the Boiler and Pressure Vessel Code, which was recently published to guide design of high-pressure hydrogen vessels. Three definitions of threshold were established for the two test methods: K{sub THi}* is the maximum applied stress intensity factor for which no crack extension was observed under constant displacement; K{sub THa} is the stress intensity factor at the arrest position for a crack that extended under constant displacement; and K{sub JH} is the stress intensity factor at the onset of crack extension under rising displacement. The apparent crack initiation threshold under constant displacement, K{sub THi}*, and the crack arrest threshold, K{sub THa}, were both found to be non-conservative due to the hydrogen exposure and crack-tip deformation histories associated with typical procedures for sustained-load cracking tests under constant displacement. In contrast, K{sub JH}, which is measured under concurrent rising displacement and hydrogen gas exposure, provides a more conservative hydrogen-assisted fracture threshold that is relevant to structural components in which sub-critical crack extension is driven by internal hydrogen gas pressure.

  5. Measurement and interpretation of threshold stress intensity factors for steels in high-pressure hydrogen gas.

    SciTech Connect (OSTI)

    Nibur, Kevin A.

    2010-11-01

    Threshold stress intensity factors were measured in high-pressure hydrogen gas for a variety of low alloy ferritic steels using both constant crack opening displacement and rising crack opening displacement procedures. The sustained load cracking procedures are generally consistent with those in ASME Article KD-10 of Section VIII Division 3 of the Boiler and Pressure Vessel Code, which was recently published to guide design of high-pressure hydrogen vessels. Three definitions of threshold were established for the two test methods: K{sub THi}* is the maximum applied stress intensity factor for which no crack extension was observed under constant displacement; K{sub THa} is the stress intensity factor at the arrest position for a crack that extended under constant displacement; and K{sub JH} is the stress intensity factor at the onset of crack extension under rising displacement. The apparent crack initiation threshold under constant displacement, K{sub THi}*, and the crack arrest threshold, K{sub THa}, were both found to be non-conservative due to the hydrogen exposure and crack-tip deformation histories associated with typical procedures for sustained-load cracking tests under constant displacement. In contrast, K{sub JH}, which is measured under concurrent rising displacement and hydrogen gas exposure, provides a more conservative hydrogen-assisted fracture threshold that is relevant to structural components in which sub-critical crack extension is driven by internal hydrogen gas pressure.

  6. Laser thermoelastic generation in metals above the melt threshold

    SciTech Connect (OSTI)

    Every, A. G.; Utegulov, Z. N.; Veres, I. A.

    2013-11-28

    An approach is presented for calculating thermoelastic generation of ultrasound in a metal plate exposed to nanosecond pulsed laser heating, sufficient to cause melting but not ablation. Detailed consideration is given to the spatial and temporal profiles of the laser pulse, penetration of the laser beam into the sample, the appearance and subsequent growth and then contraction of the melt pool, and the time dependent thermal conduction in the melt and surrounding solid throughout. The excitation of the ultrasound takes place during and shortly after the laser pulse and occurs predominantly within the thermal diffusion length of a micron or so beneath the surface. It is shown how, because of this, the output of the thermal simulations can be expressed as axially symmetric transient radial and normal surface force distributions. The epicentral displacement response to these force distributions is obtained by two methods, the one based on the elastodynamic Green's functions for plate geometry determined by the Cagniard generalized ray method and the other using a finite element numerical method. The two approaches are in very close agreement. Numerical simulations are reported on the epicentral displacement response of a 3.12 mm thick tungsten plate irradiated with a 4 ns pulsed laser beam with Gaussian spatial profile, at intensities below and above the melt threshold.

  7. MinorConstructionThresholdGuidance.PDF | Department of Energy

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    MinorConstructionThresholdGuidance.PDF MinorConstructionThresholdGuidance.PDF (165.68 KB) More Documents & Publications Audit Report: OAS-M-15-02 CX-008733: Categorical Exclusion Determination Microsoft PowerPoint - 04 Melendez Rimando Restructuring of EM Portfolio Briefing 3 March 2010 rev 2 rcvd 8 Mar 1100 [Compatibi

  8. Stochastic generation of explicit pore structures by thresholding Gaussian random fields

    SciTech Connect (OSTI)

    Hyman, Jeffrey D.; Winter, C. Larrabee

    2014-11-15

    We provide a description and computational investigation of an efficient method to stochastically generate realistic pore structures. Smolarkiewicz and Winter introduced this specific method in pores resolving simulation of Darcy flows (Smolarkiewicz and Winter, 2010 [1]) without giving a complete formal description or analysis of the method, or indicating how to control the parameterization of the ensemble. We address both issues in this paper. The method consists of two steps. First, a realization of a correlated Gaussian field, or topography, is produced by convolving a prescribed kernel with an initial field of independent, identically distributed random variables. The intrinsic length scales of the kernel determine the correlation structure of the topography. Next, a sample pore space is generated by applying a level threshold to the Gaussian field realization: points are assigned to the void phase or the solid phase depending on whether the topography over them is above or below the threshold. Hence, the topology and geometry of the pore space depend on the form of the kernel and the level threshold. Manipulating these two user prescribed quantities allows good control of pore space observables, in particular the Minkowski functionals. Extensions of the method to generate media with multiple pore structures and preferential flow directions are also discussed. To demonstrate its usefulness, the method is used to generate a pore space with physical and hydrological properties similar to a sample of Berea sandstone. -- Graphical abstract: -- Highlights: An efficient method to stochastically generate realistic pore structures is provided. Samples are generated by applying a level threshold to a Gaussian field realization. Two user prescribed quantities determine the topology and geometry of the pore space. Multiple pore structures and preferential flow directions can be produced. A pore space based on Berea sandstone is generated.

  9. Damage threshold of platinum coating used for optics for self...

    Office of Scientific and Technical Information (OSTI)

    used for optics for self-seeding of soft x-ray free electron laser Citation Details In-Document Search Title: Damage threshold of platinum coating used for optics for ...

  10. Incoherent photoproduction of {eta} mesons from the deuteron near threshold

    SciTech Connect (OSTI)

    Sibirtsev, A.; Elster, Ch.; Haidenbauer, J.; Speth, J.

    2001-08-01

    Incoherent photoproduction of the {eta} meson on the deuteron is studied for photon energies from threshold to 800 MeV. The dominant contribution, the {gamma}N-{eta}N amplitude, is described within an isobar model. The final state interaction derived from the CD-Bonn potential is included and found to be important for the description of the production cross section close to threshold. Possible effects from the {eta}N final state interaction are discussed.

  11. Review of recent theories and experiments for improving high-power microwave window breakdown thresholds

    SciTech Connect (OSTI)

    Chang Chao; Liu Guozhi; Tang Chuanxiang; Chen Changhua; Fang Jinyong

    2011-05-15

    Dielectric window breakdown is a serious challenge in high-power microwave (HPM) transmission and radiation. Breakdown at the vacuum/dielectric interface is triggered by multipactor and finally realized by plasma avalanche in the ambient desorbed or evaporated gas layer above the dielectric. Methods of improving breakdown thresholds are key challenges in HPM systems. First, the main theoretical and experimental progress is reviewed. Next, the mechanisms of multipactor suppression for periodic rectangular and triangular surface profiles by dynamic analysis and particle-in-cell simulations are surveyed. Improved HPM breakdown thresholds are demonstrated by proof-of-principle and multigigawatt experiments. The current theories and experiments of using dc magnetic field to resonantly accelerate electrons to suppress multipactor are also synthesized. These methods of periodic profiles and magnetic field may solve the key issues of HPM vacuum dielectric breakdown.

  12. Long-Range Validity of Threshold Laws in Inner-Shell Photodetachment

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Wednesday, 29 March 2006 00:00 A threshold law describes the dependence of a reaction ... threshold behavior with a threshold law or a departure from it can be a sensitive ...

  13. Communication: Classical threshold law for ion-neutral-neutral three-body recombination

    SciTech Connect (OSTI)

    Pérez-Ríos, Jesús; Greene, Chris H.

    2015-07-28

    A very recently method for classical trajectory calculations for three-body collision [Pérez-Ríos et al., J. Chem. Phys. 140, 044307 (2014)] has been applied to describe ion-neutral-neutral ternary processes for low energy collisions: 0.1 mK–10 mK. As a result, a threshold law for the three-body recombination cross section is obtained and corroborated numerically. The derived threshold law predicts the formation of weakly bound dimers, with binding energies comparable to the collision energy of the collisional partners. In this low energy range, this analysis predicts that molecular ions should dominate over molecular neutrals as the most products formed.

  14. Near-threshold photoproduction of Φ mesons from deuterium

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Qian, X.; Chen, W.; Gao, H.; Hicks, K.; Kramer, K.; Laget, J. M.; Mibe, T.; Qiang, Y.; Stepanyan, S.; Tedeschi, D. J.; et al

    2011-01-05

    In this report, we measure the differential cross section onmore » $$\\phi$$-meson photoproduction from deuterium near the production threshold for a proton using the CLAS detector and a tagged-photon beam in Hall B at Jefferson Lab. The measurement was carried out by a triple coincidence detection of a proton, $K^+$ and $K^-$ near the theoretical production threshold of 1.57 GeV. Moreover, the extracted differential cross sections $$\\frac{d\\sigma}{dt}$$ for the initial photon energy from 1.65-1.75 GeV are consistent with predictions based on a quasifree mechanism. Ultimately, this experiment establishes a baseline for a future experimental search for an exotic $$\\phi$$-N bound state from heavier nuclear targets utilizing subthreshold/near-threshold production of $$\\phi$$ mesons.« less

  15. On the mixing time of geographical threshold graphs

    SciTech Connect (OSTI)

    Bradonjic, Milan

    2009-01-01

    In this paper, we study the mixing time of random graphs generated by the geographical threshold graph (GTG) model, a generalization of random geometric graphs (RGG). In a GTG, nodes are distributed in a Euclidean space, and edges are assigned according to a threshold function involving the distance between nodes as well as randomly chosen node weights. The motivation for analyzing this model is that many real networks (e.g., wireless networks, the Internet, etc.) need to be studied by using a 'richer' stochastic model (which in this case includes both a distance between nodes and weights on the nodes). We specifically study the mixing times of random walks on 2-dimensional GTGs near the connectivity threshold. We provide a set of criteria on the distribution of vertex weights that guarantees that the mixing time is {Theta}(n log n).

  16. Threshold responses to interacting global changes in a California grassland ecosystem

    SciTech Connect (OSTI)

    Field, Christopher; Cortinas, Susan

    2015-02-02

    Final Report for Threshold responses to interacting global changes in a California grassland ecosystem

  17. A Survey of Architectural Techniques for Near-Threshold Computing

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Mittal, Sparsh

    2015-12-28

    Energy efficiency has now become the primary obstacle in scaling the performance of all classes of computing systems. In low-voltage computing and specifically, near-threshold voltage computing (NTC), which involves operating the transistor very close to and yet above its threshold voltage, holds the promise of providing many-fold improvement in energy efficiency. However, use of NTC also presents several challenges such as increased parametric variation, failure rate and performance loss etc. Our paper surveys several re- cent techniques which aim to offset these challenges for fully leveraging the potential of NTC. By classifying these techniques along several dimensions, we also highlightmore » their similarities and differences. Ultimately, we hope that this paper will provide insights into state-of-art NTC techniques to researchers and system-designers and inspire further research in this field.« less

  18. Threshold π0 Photoproduction on Transverse Polarised Protons at MAMI

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Schumann, S.

    2015-09-14

    Polarisation-dependent differential cross sections σT associated with the target asymmetry T have been measured for the reaction γ p-→ p π0 with transverse target polarisation from π0 threshold up to photon energies of 190 MeV. Additionally, the data were obtained using a frozen-spin butanol target with the Crystal Ball / TAPS detector set-up and the Glasgow photon tagging system at the Mainz Microtron MAMI. Our results for σT have been used in combination with our previous measurements of the unpolarised cross section σ0 and the beam asymmetry Σ for a model-independent determination of S and P wave multipoles in themore » π0 threshold region, which includes for the first time a direct determination of the imaginary part of the E0+ multipole.« less

  19. Crystalline perfection, birefringence and laser damage threshold properties of piperidinium p-hydroxybenzoate

    SciTech Connect (OSTI)

    Sudhahar, S.; Zahid, I. MD; Kumar, M. Krishna; Kumar, R. Mohan

    2015-06-24

    Piperidinium p-hydroxybenzoate (PPHB) crystal was grown by slow evaporation method. Single crystal X-ray diffraction studies confirm that PPHB crystallizes in monoclinic crystal system with noncentrosymmetric space group Cc. The crystalline perfection of the grown crystal was evaluated by using high resolution X-ray diffractometry. UV-Visible transmission and birefringence studies were employed on the grown PPHB crystal. The laser induced damage threshold value was estimated using Nd:YAG laser. Thermal behavior of PPHB crystal has been investigated by TG-DTA analyses. Etching studies have been performed to assess the growth pattern of PPHB crystal.

  20. Predicting threshold and location of laser damage on optical surfaces

    DOE Patents [OSTI]

    Siekhaus, Wigbert

    1987-01-01

    An apparatus useful in the prediction of the damage threshold of various optical devices, the location of weak spots on such devices and the location, identification, and elimination of optical surface impurities comprising, a focused and pulsed laser, an photo electric detector/imaging means, and a timer. The weak spots emit photoelectrons when subjected to laser intensities that are less than the intensity actually required to produce the damage. The weak spots may be eliminated by sustained exposure to the laser beam.

  1. Long-Range Validity of Threshold Laws in Inner-Shell Photodetachment

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Long-Range Validity of Threshold Laws in Inner-Shell Photodetachment Long-Range Validity of Threshold Laws in Inner-Shell Photodetachment Print Wednesday, 29 March 2006 00:00 A threshold law describes the dependence of a reaction yield near a reaction threshold. It is also a signature of the physical forces involved in the reaction, so the agreement of an observed threshold behavior with a threshold law or a departure from it can be a sensitive probe into how well the reaction physics is

  2. Data center cooling method

    DOE Patents [OSTI]

    Chainer, Timothy J.; Dang, Hien P.; Parida, Pritish R.; Schultz, Mark D.; Sharma, Arun

    2015-08-11

    A method aspect for removing heat from a data center may use liquid coolant cooled without vapor compression refrigeration on a liquid cooled information technology equipment rack. The method may also include regulating liquid coolant flow to the data center through a range of liquid coolant flow values with a controller-apparatus based upon information technology equipment temperature threshold of the data center.

  3. Predicting threshold and location of laser damage on optical surfaces

    DOE Patents [OSTI]

    Siekhaus, W.

    1985-02-04

    Disclosed is an apparatus useful in the prediction of the damage threshold of various optical devices, the location of weak spots on such devices and the location, identification, and elimination of optical surface impurities. The apparatus comprises a focused and pulsed laser, a photo electric detector/imaging means, and a timer. The weak spots emit photoelectrons when subjected to laser intensities that are less than the intensity actually required to produce the damage. The weak spots may be eliminated by sustained exposure to the laser beam.

  4. The NEPA threshold question revisited: Proposed'' actions and continuing'' activities

    SciTech Connect (OSTI)

    Wolff, T.A. ); Hansen, R.P. )

    1993-01-01

    The National Environmental Policy Act (NEPA) requires Federal agencies to include a detailed statement'' in every recommendation or report on proposals'' for major Federal actions significantly affecting the quality of the human environment.'' Unless the three elements of a proposal are present (major, federal, and action), preparation of a detailed statement is not required. This paper addresses the practical decision-making dilemma that attends determinations of what types of Federal activities meet the NEPA threshold test under what kinds of varying circumstances. The authors' experience with the US Dept. of Energy (DOE) NEPA documentation is used to discuss how decisions may be made to determine whether a proposed action qualifies for a categorical exclusion'' or whether it requires preparation of an environmental assessment (EA) or an environmental impact statement (EIS). The concept of new'' actions versus continuing'' actions which may be bounded'' by previous NEPA documentation is also discussed. A dichotomous key for separating or combining Federal action'' candidates for different levels of NEPA documentation is provided. Leading court opinions on the threshold question and related issues are discussed in lay terms.

  5. Distortion of power law blinking with binning and thresholding

    SciTech Connect (OSTI)

    Amecke, Nicole; Heber, André; Cichos, Frank

    2014-03-21

    Fluorescence intermittency is a random switching between emitting (on) and non-emitting (off) periods found for many single chromophores such as semiconductor quantum dots and organic molecules. The statistics of the duration of on- and off-periods are commonly determined by thresholding the emission time trace of a single chromophore and appear to be power law distributed. Here we test with the help of simulations if the experimentally determined power law distributions can actually reflect the underlying statistics. We find that with the experimentally limited time resolution real power law statistics with exponents α{sub on/off} ≳ 1.6, especially if α{sub on} ≠ α{sub off} would not be observed as such in the experimental data after binning and thresholding. Instead, a power law appearance could simply be obtained from the continuous distribution of intermediate intensity levels. This challenges much of the obtained data and the models describing the so-called power law blinking.

  6. Investigation of the Cause of Low Blister Threshold Temperatures in the RERTR-12 and AFIP-4 Experiments

    SciTech Connect (OSTI)

    Mitchell K Meyer

    2012-06-01

    Blister–threshold testing of fuel plates is a standard method through which the safety margin for operation of plate-type in research and test reactors is assessed. The blister-threshold temperature is indicative of the ability of fuel to operate at high temperatures for short periods of time (transient conditions) without failure. This method of testing was applied to the newly developed U-Mo monolithic fuel system. Blister annealing studies on the U-Mo monolithic fuel plates began in 2007, with the Reduced Enrichment for Research and Test Reactors (RERTR)-6 experiment, and they have continued as the U-Mo fuel system has evolved through the research and development process. Blister anneal threshold temperatures from early irradiation experiments (RERTR-6 through RERTR-10) ranged from 400 to 500°C. These temperatures were projected to be acceptable for NRC-licensed research reactors and the high-power Advanced Test Reactor (ATR) and the High Flux Isotope Reactor (HFIR) based on current safety-analysis reports (SARs). Initial blister testing results from the RERTR-12 experiment capsules X1 and X2 showed a decrease in the blister-threshold temperatures. Blister threshold temperatures from this experiment ranged from 300 to 400°C. Selected plates from the AFIP-4 experiment, which was fabricated using a process similar to that used to fabricate the RERTR-12 experiment, also underwent blister testing to determine whether results would be similar. The measured blister-threshold temperatures from the AFIP-4 plates fell within the same blister-threshold temperature range measured in the RERTR-12 plates. Investigation of the cause of this decrease in bister threshold temperature is being conducted under the guidance of Idaho National Laboratory PLN-4155, “Analysis of Low Blister Threshold Temperatures in the RERTR-12 and AFIP-4 Experiments,” and is driven by hypotheses. The main focus of the investigation is in the following areas: 1. Fabrication variables 2. Pre

  7. Long-Range Validity of Threshold Laws in Inner-Shell Photodetachment

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Long-Range Validity of Threshold Laws in Inner-Shell Photodetachment Print A threshold law describes the dependence of a reaction yield near a reaction threshold. It is also a signature of the physical forces involved in the reaction, so the agreement of an observed threshold behavior with a threshold law or a departure from it can be a sensitive probe into how well the reaction physics is understood. A collaboration from Western Michigan University, the ALS, and Denison University has now shown

  8. Long-Range Validity of Threshold Laws in Inner-Shell Photodetachment

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Long-Range Validity of Threshold Laws in Inner-Shell Photodetachment Print A threshold law describes the dependence of a reaction yield near a reaction threshold. It is also a signature of the physical forces involved in the reaction, so the agreement of an observed threshold behavior with a threshold law or a departure from it can be a sensitive probe into how well the reaction physics is understood. A collaboration from Western Michigan University, the ALS, and Denison University has now shown

  9. Direct Measurement of the Bubble Nucleation Energy Threshold in a CF3I Bubble Chamber

    SciTech Connect (OSTI)

    Behnke, E.; Benjamin, T.; Brice, S. J.; Broemmelsiek, D.; Collar, J. I.; Cooper, P. S.; Crisler, M.; Dahl, C. E.; Fustin, D.; Hall, Jeter C.; Harnish, C.; Levine, I.; Lippincott, W. H.; Moan, T.; Nania, T.; Neilson, R.; Ramberg, E.; Robinson, A. E.; Ruschman, M.; Sonnenschein, Andrew; Vazquez-Jauregui, E.; RIvera, R. A.; Uplegger, L.

    2013-07-30

    Here, we measured the energy threshold and efficiency for bubble nucleation from iodine recoils in a CF3I bubble chamber in the energy range of interest for a dark matter search. These interactions cannot be probed by standard neutron calibration methods, so we develop a new technique by observing the elastic scattering of 12 GeV/c negative pions. The pions are tracked with a silicon pixel telescope and the reconstructed scattering angle provides a measure of the nuclear recoil kinetic energy. The bubble chamber was operated with a nominal threshold of (13.6±0.6) keV. Interpretation of the results depends on the response to fluorine and carbon recoils, but in general we find agreement with the predictions of the classical bubble-nucleation theory. Moreover, this measurement confirms the applicability of CF3I as a target for spin-independent dark matter interactions and represents a novel technique for calibration of superheated fluid detectors.

  10. ZnO-PVA nanocomposite films for low threshold optical limiting applications

    SciTech Connect (OSTI)

    Viswanath, Varsha; Beenakumari, C.; Muneera, C. I.

    2014-10-15

    Zinc oxide-PVA nanocomposite films were fabricated adopting a simple method based on solution-casting, incorporating small weight percentages (<1.2 wt%) of ZnO in PVA (∼0.625×10{sup −3}M to 7×10{sup −3}M), and their structure, morphology, linear and low threshold nonlinear optical properties were investigated. The films were characterized as nanostructured ZnO encapsulated between the molecules/chains of the semicrystalline host polymer PVA. The samples exhibited low threshold nonlinear absorption and negative nonlinear refraction, as studied using the Z-scan technique. A switchover from SA to RSA was observed as the concentration of ZnO was increased. The optical limiting of 632.8 nm CW laser light displayed by these nanocomposite films is also demonstrated. The estimated values of the effective coefficients of nonlinear absorption, nonlinear refraction and third-order nonlinear susceptibility, |χ{sup (3)}|, compared to those reported for continuous wave laser light excitation, measure up to the highest among them. The results show that the ZnO-PVA nanocomposite films have great potential applications in future optical and photonic devices.

  11. Reexamination of an anomaly in near-threshold pair production

    SciTech Connect (OSTI)

    De Braeckeleer, L.; Adelberger, E.G.; Garcia, A. )

    1992-11-01

    We investigated a reported anomaly in near-threshold pair production, using radioactive sources to measure the {gamma}+Ge{r arrow}{ital e}{sup +}+{ital e}{sup {minus}}+Ge cross-section at {ital E}{sub {gamma}}=1063, 1086, 1112, 1173, 1213, 1299, 1332, and 1408 keV. Although the data agree with the theory (numerical calculations based on an exact partial-wave formulation for a screened central potential) at the higher energies, the data lie above the theory at 1063, 1082, and 1112 keV. The discrepancy is reduced by including the final-state Coulomb interaction between the {ital e}{sup +} and {ital e}{sup {minus}}.

  12. Above-threshold ionization beyond the dipole approximation

    SciTech Connect (OSTI)

    Klaiber, Michael; Hatsagortsyan, Karen Z.; Keitel, Christoph H.

    2005-03-01

    A generalization of the analytical theory of above-threshold ionization in the single active electron approximation is developed while taking into account leading non-dipole and relativistic corrections in the starting Hamiltonian. Special interest is placed on the high energy part of the photoelectron spectrum which consists of a plateau and a characteristic cutoff. It is shown that the correction due to the magnetic component of the laser field gives rise to a decrease of the plateau height, an increase of the maximal cutoff energy, and a drift of the emitted electrons in propagation direction of the laser field. Furthermore, the influence of the relativistic mass shift may become non-neglible by reducing the cutoff energy significantly. Spin effects or the Zitterbewegung play a comparably minor role in the investigated parameter regime of suboptical frequencies and high but not ultra-high laser intensities.

  13. Bone sarcoma in humans induced by radium: A threshold response?

    SciTech Connect (OSTI)

    Rowland, R.E.

    1996-08-01

    The radium 226 and radium 228 have induced malignancies in the skeleton (primarily bone sarcomas) of humans. They have also induced carcinomas in the paranasal sinuses and mastoid air cells. There is no evidence that any leukemias or any other solid cancers have been induced by internally deposited radium. This paper discuses a study conducted on the dial painter population. This study made a concerted effort to verify, for each of the measured radium cases, the published values of the skeletal dose and the initial intake of radium. These were derived from body content measurements made some 40 years after the radium intake. Corrections to the assumed radium retention function resulted in a considerable number of dose changes. These changes have changed the shape of the dose response function. It now appears that the induction of bone sarcomas is a threshold process.

  14. Resonances above the proton threshold in 26Si

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chipps, Kelly A.

    2016-03-06

    26Al remains an intriguing target for observational gamma-ray astronomy, thanks to its characteristic decay. The 25Al(p, )26Si reaction is part of a chain that bypasses the production of the observable 26Alg in favor of the isomeric state; its rate at novae temperatures is dominated by a resonance around 400 keV, the precise location and J assignment of which has been hotly debated. Considerable confusion in this regard has arisen from the use of outdated excitation energies and masses. Here, a reanalysis of previous work is completed to first, elucidate the confusion regarding the level structure just above the proton threshold,more » and second, provide focus to future studies.« less

  15. ARM - VAP Product - lbtm3minnis

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    minnis Documentation lbtm-minnis : XDC documentation Data Management Facility Plots (Quick Looks) ARM Data Discovery Browse Data Comments? We would love to hear from you! Send us a note below or call us at 1-888-ARM-DATA. Send VAP Output : LBTM3MINNIS Layered Bispectral Threshold Method (LBTM) cloud products derived from GMS-5 Active Dates 1998.01.03 - 2003.05.21 Originating VAP Process Minnis Cloud Products Using LBTM Algorithm : LBTM-MINNIS Measurements The measurements below provided by this

  16. The Cryogenic Dark Matter Search low ionization-threshold experiment

    SciTech Connect (OSTI)

    Basu Thakur, Ritoban

    2014-01-01

    Over 80 years ago we discovered the presence of Dark Matter in our universe. Endeavors in astronomy and cosmology are in consensus with ever improving precision that Dark Matter constitutes an essential 27% of our universe. The Standard Model of Particle Physics does not provide any answers to the Dark Matter problem. It is imperative that we understand Dark Matter and discover its fundamental nature. This is because, alongside other important factors, Dark Matter is responsible for formation of structure in our universe. The very construct in which we sit is defined by its abundance. The Milky Way galaxy, hence life, wouldn't have formed if small over densities of Dark Matter had not caused sufficient accretion of stellar material. Marvelous experiments have been designed based on basic notions to directly and in-directly study Dark Matter, and the Cryogenic Dark Matter Search (CDMS) experiment has been a pioneer and forerunner in the direct detection field. Generations of the CDMS experiment were designed with advanced scientific upgrades to detect Dark Matter particles of mass O(100) GeV/c2. This mass-scale was set primarily by predictions from Super Symmetry. Around 2013 the canonical SUSY predictions were losing some ground and several observations (rather hints of signals) from various experiments indicated to the possibility of lighter Dark Matter of mass O(10) GeV/c2. While the SuperCDMS experiment was probing the regular parameter space, the CDMSlite experiment was conceived to dedicatedly search for light Dark Matter using a novel technology. "CDMSlite" stands for CDMS - low ionization threshold experiment. Here we utilize a unique electron phonon coupling mechanism to measure ionization generated by scattering of light particles. Typically signals from such low energy recoils would be washed under instrumental noise. In CDMSlite via generation of Luke-Neganov phonons we can detect the small ionization energies, amplified in phonon

  17. DOE Hydrogen and Fuel Cells Program Record 11007: Hydrogen Threshold Cost

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Calculation | Department of Energy 1007: Hydrogen Threshold Cost Calculation DOE Hydrogen and Fuel Cells Program Record 11007: Hydrogen Threshold Cost Calculation The hydrogen threshold cost is defined as the hydrogen cost in the range of $2.00-$4.00/gge (2007$), which represents the cost at which hydrogen fuel cell electric vehicles are projected to become competitive on a cost per mile basis with the competing vehicles (gasoline in hybrid-electric vehicles) in 2020. This record from the

  18. Laser damage threshold measurements of optical materials for direct laser accelerators

    SciTech Connect (OSTI)

    Soong, Ken; Byer, R. L.; Colby, E. R.; England, R. J.; Peralta, E. A.

    2012-12-21

    The laser-damage threshold is a fundamental limit for any dielectric laser-driven accelerator and is set by the material of the structure. In this paper, we present a theoretical model of the laser damage mechanism, in comparison with experimental data on the damage threshold of silicon. Additionally, we present damage threshold measurement data of various optical materials, most of which have not been previously characterized in the picosecond-regime.

  19. No-Impact Threshold Values for NRAP's Reduced Order Models

    SciTech Connect (OSTI)

    Last, George V.; Murray, Christopher J.; Brown, Christopher F.; Jordan, Preston D.; Sharma, Maneesh

    2013-02-01

    The purpose of this study was to develop methodologies for establishing baseline datasets and statistical protocols for determining statistically significant changes between background concentrations and predicted concentrations that would be used to represent a contamination plume in the Gen II models being developed by NRAP’s Groundwater Protection team. The initial effort examined selected portions of two aquifer systems; the urban shallow-unconfined aquifer system of the Edwards-Trinity Aquifer System (being used to develop the ROM for carbon-rock aquifers, and the a portion of the High Plains Aquifer (an unconsolidated and semi-consolidated sand and gravel aquifer, being used to development the ROM for sandstone aquifers). Threshold values were determined for Cd, Pb, As, pH, and TDS that could be used to identify contamination due to predicted impacts from carbon sequestration storage reservoirs, based on recommendations found in the EPA’s ''Unified Guidance for Statistical Analysis of Groundwater Monitoring Data at RCRA Facilities'' (US Environmental Protection Agency 2009). Results from this effort can be used to inform a ''no change'' scenario with respect to groundwater impacts, rather than the use of an MCL that could be significantly higher than existing concentrations in the aquifer.

  20. Observed Minimum Illuminance Threshold for Night Market Vendors in Kenya who use LED Lamps

    SciTech Connect (OSTI)

    Johnstone, Peter; Jacobson, Arne; Mills, Evan; Radecsky, Kristen

    2009-03-21

    Creation of light for work, socializing, and general illumination is a fundamental application of technology around the world. For those who lack access to electricity, an emerging and diverse range of LED based lighting products hold promise for replacing and/or augmenting their current fuel-based lighting sources that are costly and dirty. Along with analysis of environmental factors, economic models for total cost-ofownership of LED lighting products are an important tool for studying the impacts of these products as they emerge in markets of developing countries. One important metric in those models is the minimum illuminance demanded by end-users for a given task before recharging the lamp or replacing batteries. It impacts the lighting service cost per unit time if charging is done with purchased electricity, batteries, or charging services. The concept is illustrated in figure 1: LED lighting products are generally brightest immediately after the battery is charged or replaced and the illuminance degrades as the battery is discharged. When a minimum threshold level of illuminance is reached, the operational time for the battery charge cycle is over. The cost to recharge depends on the method utilized; these include charging at a shop at a fixed price per charge, charging on personal grid connections, using solar chargers, and purchasing dry cell batteries. This Research Note reports on the observed"charge-triggering" illuminance level threshold for night market vendors who use LED lighting products to provide general and task oriented illumination. All the study participants charged with AC power, either at a fixed-price charge shop or with electricity at their home.

  1. Pulsed laser generation of ultrasound in a metal plate between the melting and ablation thresholds

    SciTech Connect (OSTI)

    Every, A. G.; Utegulov, Z. N.; Veres, I. A.

    2015-03-31

    The generation of ultrasound in a metal plate exposed to nanosecond pulsed laser heating, sufficient to cause melting but not ablation, is treated. Consideration is given to the spatial and temporal profiles of the laser pulse, penetration of the laser beam into the sample, the evolution of the melt pool, and thermal conduction in the melt and surrounding solid. The excitation of the ultrasound takes place over a few nanoseconds, and occurs predominantly within the thermal diffusion length of a micron or so beneath the surface. Because of this, the output of the thermal simulations can be represented as axially symmetric transient radial and normal surface force distributions. The epicentral displacement response at the opposite surface to these forces is obtained by two methods, the one based on the elastodynamic Green’s functions for plate geometry determined by the Cagniard generalized ray method, and the other using a finite element numerical method. The two approaches are in very close agreement. Numerical simulations are reported of the epicentral displacement response of a 3.12mm thick tungsten plate irradiated with a 4 ns pulsed laser beam with Gaussian spatial profile, at intensities below and above the melt threshold. Comparison is made between results obtained using available temperature dependent thermophysical data, and room temperature materials constants except near the melting point.

  2. Domain imaging on multiferroic BiFeO{sub 3}(001) by linear and circular dichroism in threshold photoemission

    SciTech Connect (OSTI)

    Sander, Anke; Christl, Maik; Chiang, Cheng-Tien; Alexe, Marin; Widdra, Wolf

    2015-12-14

    We demonstrate ferroelectric domain imaging at BiFeO{sub 3}(001) single crystal surfaces with laser-based threshold photoemission electron microscopy (PEEM). Work function differences and linear dichroism allow for the identification of the eight independent ferroelectric domain configurations in the PEEM images. There, the determined domain structure is consistent with piezoresponse force microscopy of the sample surface and can also be related to the circular dichroic PEEM images. Our results provide a method for efficient mapping of complex ferroelectric domains with laser-excited PEEM and may allow lab-based time-resolved studies of the domain dynamics in the future.

  3. A threshold gas Cerenkov detector for the spin asymmetries of...

    Office of Scientific and Technical Information (OSTI)

    GrantContract Number: AC05-06OR23177; FG02-94ER4084 Type: Accepted Manuscript Journal Name: Nuclear Instruments and Methods in Physics Research. Section A, Accelerators, ...

  4. JET/DIII-D size scaling of the H-mode power threshold

    SciTech Connect (OSTI)

    Carlstrom, T.N.; Campbell, D.J.; Cordey, J.G.

    1995-10-01

    Previous scaling results indicate that the H-mode power threshold increases nearly linearly with the line averaged density, {bar n}{sub e}, and the toroidal field, B{sub t}. The power threshold was measured in similar, ITER-like, discharges in JET and DIII-D, at the same {bar n}{sub e} and B{sub t} in order to determine the size scaling of the power threshold. The results indicate a size scaling proportional to the surface area, S{sup 0.5}, which is weaker than the linear surface area dependence previously assumed.

  5. Higgs boson gluon-fusion production beyond threshold in NLO QCD

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Anastasiou, Charalampos; Duhr, Claude; Dulat, Falko; Furlan, Elisabetta; Gehrmann, Thomas; Herzog, Franz; Mistlberger, Bernhard

    2015-03-01

    In this article, we compute the gluon fusion Higgs boson cross-section at NLO through the second term in the threshold expansion. This calculation constitutes a major milestone towards the full NLO cross section. Our result has the best formal accuracy in the threshold expansion currently available, and includes contributions from collinear regions besides subleading corrections from soft and hard regions, as well as certain logarithmically enhanced contributions for general kinematics. We use our results to perform a critical appraisal of the validity of the threshold approximation at NLO in perturbative QCD.

  6. Higgs boson gluon-fusion production beyond threshold in N3LO QCD

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Anastasiou, Charalampos; Duhr, Claude; Dulat, Falko; Furlan, Elisabetta; Gehrmann, Thomas; Herzog, Franz; Mistlberger, Bernhard

    2015-03-18

    In this study, we compute the gluon fusion Higgs boson cross-section at N3LO through the second term in the threshold expansion. This calculation constitutes a major milestone towards the full N3LO cross section. Our result has the best formal accuracy in the threshold expansion currently available, and includes contributions from collinear regions besides subleading corrections from soft and hard regions, as well as certain logarithmically enhanced contributions for general kinematics. We use our results to perform a critical appraisal of the validity of the threshold approximation at N3LO in perturbative QCD.

  7. PT-symmetric sinusoidal optical lattices at the symmetry-breaking threshold

    SciTech Connect (OSTI)

    Graefe, Eva-Maria [Mathematics Department, Imperial College, London SW7 2BZ (United Kingdom); Jones, H. F. [Physics Department, Imperial College, London SW7 2BZ (United Kingdom)

    2011-07-15

    The PT-symmetric potential V{sub 0}[cos(2{pi}x/a)+i{lambda}sin(2{pi}x/a)] has a completely real spectrum for {lambda}{<=}1 and begins to develop complex eigenvalues for {lambda}>1. At the symmetry-breaking threshold {lambda}=1 some of the eigenvectors become degenerate, giving rise to a Jordan-block structure for each degenerate eigenvector. In general this is expected to result in a secular growth in the amplitude of the wave. However, it has been shown in a recent paper by Longhi, by numerical simulation and by the use of perturbation theory, that for a broad initial wave packet this growth is suppressed, and instead a saturation leading to a constant maximum amplitude is observed. We revisit this problem by explicitly constructing the Bloch wave functions and the associated Jordan functions and using the method of stationary states to find the dependence on the longitudinal distance z for a variety of different initial wave packets. This allows us to show in detail how the saturation of the linear growth arises from the close connection between the contributions of the Jordan functions and those of the neighboring Bloch waves.

  8. Revision of laser-induced damage threshold evaluation from damage probability data

    SciTech Connect (OSTI)

    Bataviciute, Gintare; Grigas, Povilas; Smalakys, Linas; Melninkaitis, Andrius

    2013-04-15

    In this study, the applicability of commonly used Damage Frequency Method (DFM) is addressed in the context of Laser-Induced Damage Threshold (LIDT) testing with pulsed lasers. A simplified computer model representing the statistical interaction between laser irradiation and randomly distributed damage precursors is applied for Monte Carlo experiments. The reproducibility of LIDT predicted from DFM is examined under both idealized and realistic laser irradiation conditions by performing numerical 1-on-1 tests. A widely accepted linear fitting resulted in systematic errors when estimating LIDT and its error bars. For the same purpose, a Bayesian approach was proposed. A novel concept of parametric regression based on varying kernel and maximum likelihood fitting technique is introduced and studied. Such approach exhibited clear advantages over conventional linear fitting and led to more reproducible LIDT evaluation. Furthermore, LIDT error bars are obtained as a natural outcome of parametric fitting which exhibit realistic values. The proposed technique has been validated on two conventionally polished fused silica samples (355 nm, 5.7 ns).

  9. Linking the micro and macro: L-H transition dynamics and threshold...

    Office of Scientific and Technical Information (OSTI)

    Linking the micro and macro: L-H transition dynamics and threshold physics Citation Details In-Document Search Title: Linking the micro and macro: L-H transition dynamics and ...

  10. N 3 LO Higgs boson and Drell-Yan production at threshold: The...

    Office of Scientific and Technical Information (OSTI)

    N 3 LO Higgs boson and Drell-Yan production at threshold: The one-loop two-emission contribution Citation Details In-Document Search Title: N 3 LO Higgs boson and Drell-Yan ...

  11. The FY 2007 Budget Request - On the Threshold of Incredible Advances |

    Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site

    Department of Energy 7 Budget Request - On the Threshold of Incredible Advances The FY 2007 Budget Request - On the Threshold of Incredible Advances DOE's Office of Energy Efficiency and Renewable Energy's fiscal year 2007 budget presentation. FY07_budget_request.pdf (598.17 KB) More Documents & Publications The FY 2008 Budget Request - Twenty in Ten: Strengthening America's Energy Security The FY 2006 Budget Request Federal Support for Hydrogen and Fuel Cell Technologies

  12. Observation of the tune dependence of the stability threshold current in the PSR (Proton Storage Ring)

    SciTech Connect (OSTI)

    Wang, Tai Sen F.; Colton, E.; Lombardi, A.; Neuffer, D.V.; Thiessen, H.A.

    1989-01-01

    In the high-intensity unbunched-beam experiments carried out in the Proton Storage Ring at Los Alamos National Laboratory, the threshold current of vertical transverse instability showed pronounced differences when the betatron tune varied across an integer. In this paper, we shall present our experimental observations and discuss the possible relations between the threshold current and the machine impedance. The possible effects related to the distorted closed orbit are also discussed. 5 refs., 3 figs., 1 tab.

  13. Increase of bulk optical damage threshold fluences of KDP crystals by laser irradiation and heat treatment

    DOE Patents [OSTI]

    Swain, J.E.; Stokowski, S.E.; Milam, D.; Kennedy, G.C.; Rainer, F.

    1982-07-07

    The bulk optical damage threshold fluence of potassium dihydrogen phosphate (KDP) crystals is increased by irradiating the crystals with laser pulses of duration 1 to 20 nanoseconds of increasing fluence, below the optical damage threshold fluence for untreated crystals, or by baking the crystals for times of the order of 24 hours at temperatures of 110 to 165/sup 0/C, or by a combination of laser irradiation and baking.

  14. Measurement of the generalized form factors near threshold via γ*p → nπ+ at high Q2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Park, K.; Adhikari, K. P.; Adikaram, D.; Anghinolfi, M.; Baghdasaryan, H.; Ball, J.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Bennett, R. P.; et al

    2012-03-26

    We report the first extraction of the pion-nucleon multipoles near the production threshold for the nπ+ channel at relatively high momentum transfer (Q2 up to 4.2 GeV2). The dominance of the s-wave transverse multipole (E0+), expected in this region, allowed us to access the generalized form factor G1 within the light-cone sum rule (LCSR) framework as well as the axial form factor GA. The data analyzed in this work were collected by the nearly 4π CEBAF Large Acceptance Spectrometer (CLAS) using a 5.754-GeV electron beam on a proton target. The differential cross section and the π-N multipole E0+/GD were measuredmore » using two different methods, the LCSR and a direct multipole fit. The results from the two methods are found to be consistent and almost Q2 independent.« less

  15. Measurement of the generalized form factors near threshold via γ*p → nπ+ at high Q2

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Park, K.; Adhikari, K. P.; Adikaram, D.; Anghinolfi, M.; Baghdasaryan, H.; Ball, J.; Battaglieri, M.; Batourine, V.; Bedlinskiy, I.; Bennett, R. P.; et al

    2012-03-26

    We report the first extraction of the pion-nucleon multipoles near the production threshold for the nπ+ channel at relatively high momentum transfer (Q2 up to 4.2 GeV2). The dominance of the s-wave transverse multipole (E0+), expected in this region, allowed us to access the generalized form factor G1 within the light-cone sum rule (LCSR) framework as well as the axial form factor GA. The data analyzed in this work were collected by the nearly 4π CEBAF Large Acceptance Spectrometer (CLAS) using a 5.754-GeV electron beam on a proton target. The differential cross section and the π-N multipole E0+/GD were measuredmore »using two different methods, the LCSR and a direct multipole fit. The results from the two methods are found to be consistent and almost Q2 independent.« less

  16. De Minimis Thresholds for Federal Building Metering Appropriateness

    SciTech Connect (OSTI)

    Henderson, Jordan W.

    2015-03-31

    The U.S. Department of Energy (DOE) is required by statute and Presidential Memorandum to establish guidelines for agencies to meter their Federal buildings for energy (electricity, natural gas, and steam) and water. See 42 U.S.C. § 8253(e). DOE issued guidance in February 2006 on the installation of electric meters in Federal buildings. A recent update to the 2006 guidance accounts for more current metering practices within the Federal Government. The updated metering guidance specifies that all Federal buildings shall be considered “appropriate” for energy or water metering unless identified for potential exclusion. In developing the updated guidance to carry out the statue, Congress also directed DOE to (among other things) establish exclusions from the metering requirements based on the de minimis quantity of energy use of a Federal building, industrial process, or structure. This paper discusses the method used to identify de minimis values.

  17. Estimating Alarm Thresholds for Process Monitoring Data under Different Assumptions about the Data Generating Mechanism

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Burr, Tom; Hamada, Michael S.; Howell, John; Skurikhin, Misha; Ticknor, Larry; Weaver, Brian

    2013-01-01

    Process monitoring (PM) for nuclear safeguards sometimes requires estimation of thresholds corresponding to small false alarm rates. Threshold estimation dates to the 1920s with the Shewhart control chart; however, because possible new roles for PM are being evaluated in nuclear safeguards, it is timely to consider modern model selection options in the context of threshold estimation. One of the possible new PM roles involves PM residuals, where a residual is defined as residual = data − prediction. This paper reviews alarm threshold estimation, introduces model selection options, and considers a range of assumptions regarding the data-generating mechanism for PM residuals.more » Two PM examples from nuclear safeguards are included to motivate the need for alarm threshold estimation. The first example involves mixtures of probability distributions that arise in solution monitoring, which is a common type of PM. The second example involves periodic partial cleanout of in-process inventory, leading to challenging structure in the time series of PM residuals.« less

  18. Method for early detection of cooling-loss events

    SciTech Connect (OSTI)

    Bermudez, Sergio A.; Hamann, Hendrik; Marianno, Fernando J.

    2015-06-30

    A method of detecting cooling-loss event early is provided. The method includes defining a relative humidity limit and change threshold for a given space, measuring relative humidity in the given space, determining, with a processing unit, whether the measured relative humidity is within the defined relative humidity limit, generating a warning in an event the measured relative humidity is outside the defined relative humidity limit and determining whether a change in the measured relative humidity is less than the defined change threshold for the given space and generating an alarm in an event the change is greater than the defined change threshold.

  19. Method for early detection of cooling-loss events

    SciTech Connect (OSTI)

    Bermudez, Sergio A.; Hamann, Hendrik F.; Marianno, Fernando J.

    2015-12-22

    A method of detecting cooling-loss event early is provided. The method includes defining a relative humidity limit and change threshold for a given space, measuring relative humidity in the given space, determining, with a processing unit, whether the measured relative humidity is within the defined relative humidity limit, generating a warning in an event the measured relative humidity is outside the defined relative humidity limit and determining whether a change in the measured relative humidity is less than the defined change threshold for the given space and generating an alarm in an event the change is greater than the defined change threshold.

  20. Linking the micro and macro: L-H transition dynamics and threshold physics

    SciTech Connect (OSTI)

    Malkov, M. A. Diamond, P. H.; Miki, K.; Rice, J. E.; Tynan, G. R.

    2015-03-15

    The links between the microscopic dynamics and macroscopic threshold physics of the L → H transition are elucidated. Emphasis is placed on understanding the physics of power threshold scalings, and especially on understanding the minimum in the power threshold as a function of density P{sub thr} (n). By extending a numerical 1D model to evolve both electron and ion temperatures, including collisional coupling, we find that the decrease in P{sub thr} (n) along the low-density branch is due to the combination of an increase in collisional electron-to-ion energy transfer and an increase in the heating fraction coupled to the ions. Both processes strengthen the edge diamagnetic electric field needed to lock in the mean electric field shear for the L→H transition. The increase in P{sub thr} (n) along the high-density branch is due to the increase with ion collisionality of damping of turbulence-driven shear flows. Turbulence driven shear flows are needed to trigger the transition by extracting energy from the turbulence. Thus, we identify the critical transition physics components of the separatrix ion heat flux and the zonal flow excitation. The model reveals a power threshold minimum in density scans as a crossover between the threshold decrease supported by an increase in heat fraction received by ions (directly or indirectly, from electrons) and a threshold increase, supported by the rise in shear flow damping. The electron/ion heating mix emerges as important to the transition, in that it, together with electron-ion coupling, regulates the edge diamagnetic electric field shear. The importance of possible collisionless electron-ion heat transfer processes is explained.

  1. Measurement of the tradeoff between intrinsic emittance and quantum efficiency from a NaKSb photocathode near threshold

    SciTech Connect (OSTI)

    Maxson, Jared Cultrera, Luca; Gulliford, Colwyn; Bazarov, Ivan

    2015-06-08

    We measure the tradeoff between the quantum efficiency and intrinsic emittance from a NaKSb photocathode at three increasing wavelengths (635, 650, and 690 nm) at or below the energy of the bandgap plus the electron affinity, hν≤E{sub g}+E{sub a}. These measurements were performed using a high voltage dc gun for varied photocathode surface fields of 1.4−4.4 MV/m. Measurements of intrinsic emittance are performed using two different methods and were found to agree. At the longest wavelength available, 690 nm, the intrinsic emittance was 0.26 μm/mm-rms with a quantum efficiency of ∼10{sup −4}. The suitability of NaKSb emitting at threshold for various low emittance applications is discussed.

  2. Light-controlled electric Freedericksz threshold in dye doped liquid crystals

    SciTech Connect (OSTI)

    Lucchetti, L.; Catani, L.; Simoni, F.

    2014-05-28

    We report the results of measurements of the threshold of Freedericksz transition in a nematic liquid crystal doped by Methyl-red. We show that in case of dc field the threshold voltage can decrease or increase depending on the light dose, due to the light-induced desorption and adsorption of charge complexes from and on the irradiated surface, that has been recently demonstrated. This effect has the potential to be exploited in optical devices such as liquid crystal microlenses and spatial light modulators.

  3. Experimental Determination of Damage Threshold Characteristics of IR Compatible Optical Materials

    SciTech Connect (OSTI)

    Soong, Ken

    2011-05-20

    The accelerating gradient in a laser-driven dielectric accelerating structure is often limited by the laser damage threshold of the structure. For a given laser-driven dielectric accelerator design, we can maximize the accelerating gradient by choosing the best combination of the accelerator's constituent material and operating wavelength. We present here a model of the damage mechanism from ultrafast infrared pulses and compare that model with experimental measurements of the damage threshold of bulk silicon. Additionally, we present experimental measurements of a variety of candidate materials, thin films, and nanofabricated accelerating structures.

  4. Damage thresholds of thin film materials and high reflectors at 248 nm

    SciTech Connect (OSTI)

    Rainer, F.; Lowdermilk, W.H.; Milam, D.; Carniglia, C.K.; Hart, T.T.; Lichtenstein, T.L.

    1982-01-01

    Twenty-ns, 248-nm KrF laser pulses were used to measure laser damage thresholds for halfwave-thick layers of 15 oxide and fluoride coating materials, and for high reflectance coatings made with 13 combinations of these materials. The damage thresholds of the reflectors and single-layer films were compared to measurements of several properties of the halfwave-thick films to determine whether measurements of these properties of single-layer films to determine whether measurements of these properties of single-layer films were useful for identifying materials for fabrication of damage resistant coatings.

  5. Hurricane Sandy Contingency Operation-- Increase in Micro-Purchase and Simplified Acquisition Thresholds for Specific States and Counties

    Office of Energy Efficiency and Renewable Energy (EERE)

    The Department of Energy (DOE) Senior Procurement Executive (SPE) has increased the micro-purchase and simplified acquisition thresholds for Hurricane Sandy Contingency Operation.

  6. Influence of emission threshold of explosive emission cathodes on current waveform in foilless diodes

    SciTech Connect (OSTI)

    Wu, P.; Liu, G. Z.; Huo, S. F.; Sun, J.; Chen, C. H.

    2015-08-15

    The emission threshold of explosive emission cathodes (EECs) is an important factor for beam quality. It can affect the explosive emission delay time, the plasma expansion process on the cathode surface, and even the current amplitude when the current is not fully space-charge-limited. This paper researches the influence of the emission threshold of an annular EEC on the current waveform in a foilless diode when the current is measured by a Rogowski coil. The particle-in-cell simulation which is performed under some tolerable and necessary simplifications shows that the long explosive emission delay time of high-threshold cathodes may leave an apparent peak of displacement current on the rise edge of the current waveform, and this will occur only when the electron emission starts after this peak. The experimental researches, which are performed under a diode voltage of 1 MV and a repetitive frequency of 20 Hz, demonstrate that the graphite cathode has a lower emission threshold and a longer lifetime than the stainless steel cathode according to the variation of the peak of displacement current on the rise edge of the current waveform.

  7. Low-threshold short-cavity diode laser for a miniature atomic clock

    SciTech Connect (OSTI)

    Kargapol'tsev, Sergei V; Velichansky, Vladimir L; Vasil'ev, V V; Kobyakova, M Sh; Morozyuk, A V; Shiryaeva, N V; Konyaev, V P

    2009-06-30

    Short-cavity diode lasers (SCDLs) emitting at the 894-nm D{sub 1} line of caesium are developed. Low threshold currents and power consumption will make it possible to use these lasers in chip-size atomic clocks (CSACs) and magnetometers. The SCDL parameters are comparable with the parameters of surface-emitting lasers. (lasers)

  8. Incorporation of trace elements in Portland cement clinker: Thresholds limits for Cu, Ni, Sn or Zn

    SciTech Connect (OSTI)

    Gineys, N.; Aouad, G.; Sorrentino, F.; Damidot, D.

    2011-11-15

    This paper aims at defining precisely, the threshold limits for several trace elements (Cu, Ni, Sn or Zn) which correspond to the maximum amount that could be incorporated into a standard clinker whilst reaching the limit of solid solution of its four major phases (C{sub 3}S, C{sub 2}S, C{sub 3}A and C{sub 4}AF). These threshold limits were investigated through laboratory synthesised clinkers that were mainly studied by X-ray Diffraction and Scanning Electron Microscopy. The reference clinker was close to a typical Portland clinker (65% C{sub 3}S, 18% C{sub 2}S, 8% C{sub 3}A and 8% C{sub 4}AF). The threshold limits for Cu, Ni, Zn and Sn are quite high with respect to the current contents in clinker and were respectively equal to 0.35, 0.5, 0.7 and 1 wt.%. It appeared that beyond the defined threshold limits, trace elements had different behaviours. Ni was associated with Mg as a magnesium nickel oxide (MgNiO{sub 2}) and Sn reacted with lime to form a calcium stannate (Ca{sub 2}SnO{sub 4}). Cu changed the crystallisation process and affected therefore the formation of C{sub 3}S. Indeed a high content of Cu in clinker led to the decomposition of C{sub 3}S into C{sub 2}S and of free lime. Zn, in turn, affected the formation of C{sub 3}A. Ca{sub 6}Zn{sub 3}Al{sub 4}O{sub 15} was formed whilst a tremendous reduction of C{sub 3}A content was identified. The reactivity of cements made with the clinkers at the threshold limits was followed by calorimetry and compressive strength measurements on cement paste. The results revealed that the doped cements were at least as reactive as the reference cement.

  9. Electrical power distribution control methods, electrical energy demand monitoring methods, and power management devices

    DOE Patents [OSTI]

    Chassin, David P.; Donnelly, Matthew K.; Dagle, Jeffery E.

    2011-12-06

    Electrical power distribution control methods, electrical energy demand monitoring methods, and power management devices are described. In one aspect, an electrical power distribution control method includes providing electrical energy from an electrical power distribution system, applying the electrical energy to a load, providing a plurality of different values for a threshold at a plurality of moments in time and corresponding to an electrical characteristic of the electrical energy, and adjusting an amount of the electrical energy applied to the load responsive to an electrical characteristic of the electrical energy triggering one of the values of the threshold at the respective moment in time.

  10. Electrical power distribution control methods, electrical energy demand monitoring methods, and power management devices

    DOE Patents [OSTI]

    Chassin, David P.; Donnelly, Matthew K.; Dagle, Jeffery E.

    2006-12-12

    Electrical power distribution control methods, electrical energy demand monitoring methods, and power management devices are described. In one aspect, an electrical power distribution control method includes providing electrical energy from an electrical power distribution system, applying the electrical energy to a load, providing a plurality of different values for a threshold at a plurality of moments in time and corresponding to an electrical characteristic of the electrical energy, and adjusting an amount of the electrical energy applied to the load responsive to an electrical characteristic of the electrical energy triggering one of the values of the threshold at the respective moment in time.

  11. Wall loss of atomic nitrogen determined by ionization threshold mass spectrometry

    SciTech Connect (OSTI)

    Sode, M. Schwarz-Selinger, T.; Jacob, W.; Kersten, H.

    2014-11-21

    In the afterglow of an inductively coupled N{sub 2} plasma, relative N atom densities are measured by ionization threshold mass spectrometry as a function of time in order to determine the wall loss time t{sub wN} from the exponential decay curves. The procedure is performed with two mass spectrometers on different positions in the plasma chamber. t{sub wN} is determined for various pressures, i.e., for 3.0, 5.0, 7.5, and 10?Pa. For this conditions also the internal plasma parameters electron density n{sub e} and electron temperature T{sub e} are determined with the Langmuir probe and the rotational temperature T{sub rot}{sup N{sub 2}} of N{sub 2} is determined with the optical emission spectroscopy. For T{sub rot}{sup N{sub 2}}, a procedure is presented to evaluate the spectrum of the transition ?{sup ?}=0??{sup ?}=2 of the second positive system (C{sup 3}?{sub u}?B{sup 3}?{sub g}) of N{sub 2}. With this method, a gas temperature of 610?K is determined. For both mass spectrometers, an increase of the wall loss times of atomic nitrogen with increasing pressure is observed. The wall loss time measured with the first mass spectrometer in the radial center of the cylindrical plasma vessel increases linearly from 0.31?ms for 3?Pa to 0.82?ms for 10?Pa. The wall loss time measured with the second mass spectrometer (further away from the discharge) is about 4 times higher. A model is applied to describe the measured t{sub wN.} The main loss mechanism of atomic nitrogen for the considered pressure is diffusion to the wall. The surface loss probability ?{sub N} of atomic nitrogen on stainless steel was derived from t{sub wN} and is found to be 1 for the present conditions. The difference in wall loss times measured with the mass spectrometers on different positions in the plasma chamber is attributed to the different diffusion lengths.

  12. Method and system for controlling a rotational speed of a rotor of a turbogenerator

    DOE Patents [OSTI]

    Stahlhut, Ronnie Dean; Vuk, Carl Thomas

    2008-12-30

    A system and method controls a rotational speed of a rotor or shaft of a turbogenerator in accordance with a present voltage level on a direct current bus. A lower threshold and a higher threshold are established for a speed of a rotor or shaft of a turbogenerator. A speed sensor determines speed data or a speed signal for the rotor or shaft associated with a turbogenerator. A voltage regulator adjusts a voltage level associated with a direct current bus within a target voltage range if the speed data or speed signal indicates that the speed is above the higher threshold or below the lower threshold.

  13. Vibrational Feshbach resonances in near threshold HOCO{sup -} photodetachment: a theoretical study

    SciTech Connect (OSTI)

    Miyabe, Shungo; Haxton, Dan; Lawler, Keith; Orel, Ann; McCurdy, Bill; Rescigno, Tom

    2011-03-02

    The results of a theoretical study of HOCO{sup ?} photodetachment are presented, with a view toward understanding the origin of two peaks observed by Lu and Continetti (Phys. Rev. Lett. 99, 113005 (2007)) in the photoelectron kinetic energy spectrum very close to threshold. It is shown that the peaks can be attributed to vibrational Feshbach resonances of dipole-bound trans-HOCO{sup ?}, and not s- and p-wave shape resonances as previously assumed. Fixed-nuclei variational electron-HOCO scattering calculations are used to compute photodetachment cross sections and laboratory-frame photoelectron angular distributions. The calculations show a broad A??(#25;{pi}*)-shape resonance several eV above threshold.

  14. Mixing of partial waves near B*B̄* threshold in e⁺e⁻ annihilation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Li, Xin; Voloshin, M. B.

    2013-05-31

    We consider the production of B*B̄* meson pairs in e⁺e⁻ annihilation near the threshold. The rescattering due to pion exchange between the mesons results in a mixing between three partial wave amplitudes: two P-wave amplitudes with the total spin of the meson pair S=0 and S=2 and an F-wave amplitude. The mixing due to pion exchange with a low momentum transfer is calculable up to c.m. energy E≈15–20 MeV above the threshold. We find that the P–F mixing is numerically quite small in this energy range, while the mixing of the two P-wave amplitudes is rapidly changing with energy andmore » can reach of order one at such low energies.« less

  15. Higher certainty of the laser-induced damage threshold test with a redistributing data treatment

    SciTech Connect (OSTI)

    Jensen, Lars; Mrohs, Marius; Gyamfi, Mark; Mädebach, Heinrich; Ristau, Detlev

    2015-10-15

    As a consequence of its statistical nature, the measurement of the laser-induced damage threshold holds always risks to over- or underestimate the real threshold value. As one of the established measurement procedures, the results of S-on-1 (and 1-on-1) tests outlined in the corresponding ISO standard 21 254 depend on the amount of data points and their distribution over the fluence scale. With the limited space on a test sample as well as the requirements on test site separation and beam sizes, the amount of data from one test is restricted. This paper reports on a way to treat damage test data in order to reduce the statistical error and therefore measurement uncertainty. Three simple assumptions allow for the assignment of one data point to multiple data bins and therefore virtually increase the available data base.

  16. Threshold ?0 Photoproduction on Transverse Polarised Protons at MAMI

    SciTech Connect (OSTI)

    Schumann, S.

    2015-09-14

    Polarisation-dependent differential cross sections ?T associated with the target asymmetry T have been measured for the reaction ? p-? p ?0 with transverse target polarisation from ?0 threshold up to photon energies of 190 MeV. Additionally, the data were obtained using a frozen-spin butanol target with the Crystal Ball / TAPS detector set-up and the Glasgow photon tagging system at the Mainz Microtron MAMI. Our results for ?T have been used in combination with our previous measurements of the unpolarised cross section ?0 and the beam asymmetry ? for a model-independent determination of S and P wave multipoles in the ?0 threshold region, which includes for the first time a direct determination of the imaginary part of the E0+ multipole.

  17. Threshold Switching Characteristics of Nb/NbO2/TiN Vertical Devices

    SciTech Connect (OSTI)

    Wang, Yuhan; Comes, Ryan B.; Wolf, Stuart A.; Lu, Jiwei

    2015-11-25

    Nb/NbO2/TiN vertical structures were synthesized in-situ and patterned to devices with different contact areas. The devices exhibited threshold resistive switching with minimal hysteresis and a small EThreshold (60~90 kV/cm). The switching behavior was unipolar, and demonstrated good repeatability. A less sharp but still sizable change in the device resistance was observed up to 150 °C. It was found that the resistive switching without Nb capping layer exhibited the hysteretic behavior and much larger EThreshold (~250 kV/cm) likely due to a 2-3 nm surface Nb2O5 layer. The stable threshold switching behavior well above room temperature shows the potential applications of this device as an electronic switch.

  18. Determination of the Z` Mass and Couplings Below Threshold at the NLC

    SciTech Connect (OSTI)

    Rizzo, Thomas G.

    1996-12-31

    We investigate the capability of the NLC to indirectly determine both the mass as well as the couplings to leptons and b-quarks of a new neutral gauge boson below direct production threshold. By using data collected at several different values of the collide center of mass energy, we demonstrate how this can be done in an anonymous and model- independent manner. The procedure can be easily extended to the top and charm quark couplings.

  19. Interplay of threshold resummation and hadron mass corrections in deep inelastic processes

    SciTech Connect (OSTI)

    Accardi, Alberto; Anderle, Daniele P.; Ringer, Felix

    2015-02-01

    We discuss hadron mass corrections and threshold resummation for deep-inelastic scattering lN-->l'X and semi-inclusive annihilation e+e- → hX processes, and provide a prescription how to consistently combine these two corrections respecting all kinematic thresholds. We find an interesting interplay between threshold resummation and target mass corrections for deep-inelastic scattering at large values of Bjorken xB. In semi-inclusive annihilation, on the contrary, the two considered corrections are relevant in different kinematic regions and do not affect each other. A detailed analysis is nonetheless of interest in the light of recent high precision data from BaBar and Belle on pion and kaon production, with which we compare our calculations. For both deep inelastic scattering and single inclusive annihilation, the size of the combined corrections compared to the precision of world data is shown to be large. Therefore, we conclude that these theoretical corrections are relevant for global QCD fits in order to extract precise parton distributions at large Bjorken xB, and fragmentation functions over the whole kinematic range.

  20. High-Power Electrostatic Discharges in PETN: Threshold and Scaling Experiments

    SciTech Connect (OSTI)

    Liou, W; McCarrick, J F; Hodgin, R L; Phillips, D F

    2010-03-05

    There is a considerable set of data establishing the safety of PETN-based detonators that are insulted by electrostatic discharge (ESD) from a human body. However, the subject of ESD safety has garnered renewed interest because of the sparse data on high-power, low-impedance discharges that result when the source is a metallic object such as a tool. Experiments on as-built components, using pin-to-cap fault circuits through PETN-based detonators, showed significant evidence of a power dependence but with a very broad energy threshold and some uncertainty in the breakdown path. We have performed a series of experiments using a well-defined arc discharge path and a well-characterized source that is capable of independent variation of energy and power. Studies include threshold variation with power, arc length, powder surface area, and surface vs. bulk discharge paths. We find that an energy threshold variation with power does not appear to exist in the tested range of fractions to tens of MW, and that there are many subtleties to proper energy and power bookkeeping. We also present some test results for PBX 9407.

  1. Temperature threshold for nanorod structuring of metal and oxide films grown by glancing angle deposition

    SciTech Connect (OSTI)

    Deniz, Derya; Lad, Robert J.

    2011-01-15

    Thin films of tin (Sn), aluminum (Al), gold (Au), ruthenium (Ru), tungsten (W), ruthenium dioxide (RuO{sub 2}), tin dioxide (SnO{sub 2}), and tungsten trioxide (WO{sub 3}) were grown by glancing angle deposition (GLAD) to determine the nanostructuring temperature threshold, {Theta}{sub T}, above which adatom surface diffusion becomes large enough such that nanorod morphology is no longer formed during growth. The threshold was found to be lower in metals compared to oxides. Films were grown using both dc and pulsed dc magnetron sputtering with continuous substrate rotation over the temperature range from 291 to 866 K. Film morphologies, structures, and compositions were characterized by high resolution scanning electron microscopy, x-ray diffraction, and x-ray photoelectron spectroscopy. Films were also grown in a conventional configuration for comparison. For elemental metals, nanorod structuring occurs for films with melting points higher than that of Al (933 K) when grown at room temperature with a rotation rate of {approx}5 rpm, corresponding to a value of {Theta}{sub T}{approx_equal}0.33{+-}0.01. For the oxide films, a value of {Theta}{sub T}{approx_equal}0.5 was found, above which GLAD nanorod structuring does not occur. The existence of a nanostructuring temperature threshold in both metal and oxide GLAD films can be attributed to greater adatom mobilities as temperature is increased resulting in nonkinetically limited film nucleation and growth processes.

  2. A Low-threshold Analysis of CDMS Shallow-site Data

    SciTech Connect (OSTI)

    Akerib, D.S.; Attisha, M.J.; Baudis, L.; Bauer, D.A.; Bolozdynya, A.I.; Brink, P.L.; Bunker, R.; Cabrera, B.; Caldwell, D.O.; Chang, C.L.; Clarke, R.M.; Cooley, J.; Crisler, M.B.; Cushman, P.; DeJongh, F.; Dixon, R.; Driscoll, D.D.; Filippini, J.; Funkhouser, S.; Gaitskell, R.J.; Golwala, S.R.; /Caltech /Fermilab /Fermilab /Colorado U., Denver /Case Western Reserve U. /Texas A-M /Minnesota U. /UC, Berkeley /UC, Berkeley /Caltech /Stanford U., Phys. Dept. /UC, Santa Barbara /Stanford U., Phys. Dept. /Minnesota U. /Queen's U., Kingston /Minnesota U. /St. Olaf Coll. /Florida U. /LBL, Berkeley /UC, Berkeley /Texas A-M /UC, Santa Barbara /Syracuse U. /UC, Berkeley /Princeton U. /Case Western Reserve U. /Stanford U., Phys. Dept. /UC, Santa Barbara /Fermilab /Santa Clara U.

    2012-06-04

    Data taken during the final shallow-site run of the first tower of the Cryogenic Dark Matter Search (CDMS II) detectors have been reanalyzed with improved sensitivity to small energy depositions. Four {approx}224 g germanium and two {approx}105 g silicon detectors were operated at the Stanford Underground Facility (SUF) between December 2001 and June 2002, yielding 118 live days of raw exposure. Three of the germanium and both silicon detectors were analyzed with a new low-threshold technique, making it possible to lower the germanium and silicon analysis thresholds down to the actual trigger thresholds of {approx}1 and {approx}2 keV, respectively. Limits on the spin-independent cross section for weakly interacting massive particles (WIMPs) to elastically scatter from nuclei based on these data exclude interesting parameter space for WIMPs with masses below 9 GeV/c{sup 2}. Under standard halo assumptions, these data partially exclude parameter space favored by interpretations of the DAMA/LIBRA and CoGeNT experiments data as WIMP signals, and exclude new parameter space for WIMP masses between 3 and 4 GeV/c{sup 2}.

  3. Interplay of threshold resummation and hadron mass corrections in deep inelastic processes

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Accardi, Alberto; Anderle, Daniele P.; Ringer, Felix

    2015-02-01

    We discuss hadron mass corrections and threshold resummation for deep-inelastic scattering lN-->l'X and semi-inclusive annihilation e+e- → hX processes, and provide a prescription how to consistently combine these two corrections respecting all kinematic thresholds. We find an interesting interplay between threshold resummation and target mass corrections for deep-inelastic scattering at large values of Bjorken xB. In semi-inclusive annihilation, on the contrary, the two considered corrections are relevant in different kinematic regions and do not affect each other. A detailed analysis is nonetheless of interest in the light of recent high precision data from BaBar and Belle on pion and kaonmore » production, with which we compare our calculations. For both deep inelastic scattering and single inclusive annihilation, the size of the combined corrections compared to the precision of world data is shown to be large. Therefore, we conclude that these theoretical corrections are relevant for global QCD fits in order to extract precise parton distributions at large Bjorken xB, and fragmentation functions over the whole kinematic range.« less

  4. Method for photon activation positron annihilation analysis

    DOE Patents [OSTI]

    Akers, Douglas W.

    2006-06-06

    A non-destructive testing method comprises providing a specimen having at least one positron emitter therein; determining a threshold energy for activating the positron emitter; and determining whether a half-life of the positron emitter is less than a selected half-life. If the half-life of the positron emitter is greater than or equal to the selected half-life, then activating the positron emitter by bombarding the specimen with photons having energies greater than the threshold energy and detecting gamma rays produced by annihilation of positrons in the specimen. If the half-life of the positron emitter is less then the selected half-life, then alternately activating the positron emitter by bombarding the specimen with photons having energies greater then the threshold energy and detecting gamma rays produced by positron annihilation within the specimen.

  5. Higgs boson gluon-fusion production beyond threshold in N3LO QCD

    SciTech Connect (OSTI)

    Anastasiou, Charalampos; Duhr, Claude; Dulat, Falko; Furlan, Elisabetta; Gehrmann, Thomas; Herzog, Franz; Mistlberger, Bernhard

    2015-03-18

    In this study, we compute the gluon fusion Higgs boson cross-section at N3LO through the second term in the threshold expansion. This calculation constitutes a major milestone towards the full N3LO cross section. Our result has the best formal accuracy in the threshold expansion currently available, and includes contributions from collinear regions besides subleading corrections from soft and hard regions, as well as certain logarithmically enhanced contributions for general kinematics. We use our results to perform a critical appraisal of the validity of the threshold approximation at N3LO in perturbative QCD.

  6. Searching for low-lying multi-particle thresholds in lattice spectroscopy

    SciTech Connect (OSTI)

    Mahbub, M. Selim; CSIRO Computational Informatics, College Road, Sandy Bay, TAS 7005 ; Kamleh, Waseem; Leinweber, Derek B.; Williams, Anthony G.

    2014-03-15

    We explore the Euclidean-time tails of odd-parity nucleon correlation functions in a search for the S-wave pion–nucleon scattering-state threshold contribution. The analysis is performed using 2+1 flavor 32{sup 3}×64 PACS-CS gauge configurations available via the ILDG. Correlation matrices composed with various levels of fermion source/sink smearing are used to project low-lying states. The consideration of 25,600 fermion propagators reveals the presence of more than one state in what would normally be regarded as an eigenstate-projected correlation function. This observation is in accord with the scenario where the eigenstates contain a strong mixing of single and multi-particle states but only the single particle component has a strong coupling to the interpolating field. Employing a two-exponential fit to the eigenvector-projected correlation function, we are able to confirm the presence of two eigenstates. The lower-lying eigenstate is consistent with a Nπ scattering threshold and has a relatively small coupling to the three-quark interpolating field. We discuss the impact of this small scattering-state contamination in the eigenvector projected correlation function on previous results presented in the literature. -- Highlights: • Correlation-matrix projected correlators reveal more than one state contributing. • Results are associated with strong mixing of single and multi-particle states in QCD. • A two-exponential fit confirms the presence of two QCD eigenstates. •The lower-lying eigenstate is consistent with a nucleon–pion scattering threshold. •The impact of this small contamination on the higher-lying state is examined.

  7. Wavelength dependence of femtosecond laser-induced damage threshold of optical materials

    SciTech Connect (OSTI)

    Gallais, L. Douti, D.-B.; Commandré, M.; Batavičiūtė, G.; Pupka, E.; Ščiuka, M.; Smalakys, L.; Sirutkaitis, V.; Melninkaitis, A.

    2015-06-14

    An experimental and numerical study of the laser-induced damage of the surface of optical material in the femtosecond regime is presented. The objective of this work is to investigate the different processes involved as a function of the ratio of photon to bandgap energies and compare the results to models based on nonlinear ionization processes. Experimentally, the laser-induced damage threshold of optical materials has been studied in a range of wavelengths from 1030 nm (1.2 eV) to 310 nm (4 eV) with pulse durations of 100 fs with the use of an optical parametric amplifier system. Semi-conductors and dielectrics materials, in bulk or thin film forms, in a range of bandgap from 1 to 10 eV have been tested in order to investigate the scaling of the femtosecond laser damage threshold with the bandgap and photon energy. A model based on the Keldysh photo-ionization theory and the description of impact ionization by a multiple-rate-equation system is used to explain the dependence of laser-breakdown with the photon energy. The calculated damage fluence threshold is found to be consistent with experimental results. From these results, the relative importance of the ionization processes can be derived depending on material properties and irradiation conditions. Moreover, the observed damage morphologies can be described within the framework of the model by taking into account the dynamics of energy deposition with one dimensional propagation simulations in the excited material and thermodynamical considerations.

  8. Measurement and modeling of infrared nonlinear absorption coefficients and laser-induced damage thresholds in Ge and GaSb

    SciTech Connect (OSTI)

    Wagner, T. J.; Bohn, M. J.; Coutu, R. A. Jr.; Gonzalez, L. P.; Murray, J. M.; Guha, S.; Schepler, K. L.

    2010-10-15

    Using a simultaneous fitting technique to extract nonlinear absorption coefficients from data at two pulse widths, we measure two-photon and free-carrier absorption coefficients for Ge and GaSb at 2.05 and 2.5 {mu}m for the first time, to our knowledge. Results agreed well with published theory. Single-shot damage thresholds were also measured at 2.5 {mu}m and agreed well with modeled thresholds using experimentally determined parameters including nonlinear absorption coefficients and temperature dependent linear absorption. The damage threshold for a single-layer Al{sub 2}O{sub 3} anti-reflective coating on Ge was 55% or 35% lower than the uncoated threshold for picosecond or nanosecond pulses, respectively.

  9. Identification of the stimulated-emission threshold in high-{beta} nanoscale lasers through phase-space reconstruction

    SciTech Connect (OSTI)

    Hachair, X.; Elvira, D.; Le Gratiet, L.; Lemaitre, A.; Abram, I.; Sagnes, I.; Robert-Philip, I.; Beveratos, A.; Braive, R.; Lippi, G. L.

    2011-05-15

    Nanoscale lasers sustain a few optical modes so that the fraction of spontaneous emission {beta} funnelled into the useful (lasing) mode is high (of the order of 10{sup -1}) and the threshold, which traditionally corresponds to an abrupt kink in the light-in-light-out curve, becomes ill defined. We propose an alternative definition of the threshold that is based on the dynamical response of the laser and is valid even for {beta}=1 lasers. The laser dynamics is analyzed through a reconstruction of its phase-space trajectory for pulsed excitations. Crossing the threshold, brings about a change in the shape of the trajectory and in the area contained in it. An unambiguous determination of the threshold in terms of this change is shown theoretically and illustrated experimentally in a photonic-crystal laser.

  10. Exploration of below threshold Z{sup {prime}} mass and coupling determinations at the NLC

    SciTech Connect (OSTI)

    Rizzo, T.G.

    1997-05-01

    We examine of the capability of the Next Linear Collider to determine the mass as well as the couplings to leptons and b quarks of a new neutral gauge boson Z{sup {prime}} below direct production threshold. By using simulated data collected at several different values of {radical}(s), we demonstrate how this can be done in a model-independent manner via an anonymous case approach. The importance of beam polarization to the success of this program is discussed. The procedure is shown to be easily extended to the case of top and charm quark couplings. {copyright} {ital 1997} {ital The American Physical Society}

  11. Spin-lasers: From threshold reduction to large-signal analysis

    SciTech Connect (OSTI)

    Lee, Jeongsu; Bearden, Sean; Wasner, Evan; Žutić, Igor

    2014-07-28

    Lasers in which spin-polarized carriers are injected provide paths to different practical room temperature spintronic devices, not limited to magnetoresistive effects. Unlike the conventional understanding of spintronic devices, an optimal performance of such spin-lasers can arise for finite, not infinite, spin relaxation time. By considering spin-relaxation times of both electrons and holes, we elucidate advantages of spin-lasers over their conventional (spin-unpolarized) counterparts. In addition to the steady-state threshold reduction, spin-lasers can improve transient operation leading to shorter turn-on delay times, reduced ringing of emitted light, and an enhanced bandwidth.

  12. Self-Sputtering Far above the Runaway Threshold: An Extraordinary Metal-Ion Generator

    SciTech Connect (OSTI)

    Andersson, Joakim; Anders, Andre

    2009-01-30

    When self-sputtering is driven far above the runaway threshold voltage, energetic electrons are made available to produce 'excess plasma' far from the magnetron target. Ionization balance considerations show that the secondary electrons deliver the necessary energy to the 'remote' zone. Thereby, such a system can be an extraordinarily prolific generator of usable metal ions. Contrary to other known sources, the ion current to a substrate can exceed the discharge current. For gasless self-sputtering of copper, the usable ion current scales exponentially with the discharge voltage.

  13. Self-sputtering far above the runaway threshold: an extraordinary metal ion generator

    SciTech Connect (OSTI)

    Andersson, Joakim; Anders, Andre

    2008-12-16

    When self-sputtering is driven far above the runaway threshold voltage, energetic electrons are made available to produce"excess plasma" far from the magnetron target. Ionization balance considerations show that the secondary electrons deliver the necessary energy to the"remote" zone. Thereby, such a system can be an extraordinarily prolific generator of useable metal ions. Contrary to other known sources, the ion current to a substrate can exceed the discharge current. For gasless self-sputtering of copper, the useable ion current scales exponentially with the discharge voltage.

  14. QCD CORRECTIONS TO DILEPTON PRODUCTION NEAR PARTONIC THRESHOLD IN PP SCATTERING.

    SciTech Connect (OSTI)

    SHIMIZU, H.; STERMAN, G.; VOGELSANG, W.; YOKOYA, H.

    2005-10-02

    We present a recent study of the QCD corrections to dilepton production near partonic threshold in transversely polarized {bar p}p scattering, We analyze the role of the higher-order perturbative QCD corrections in terms of the available fixed-order contributions as well as of all-order soft-gluon resummations for the kinematical regime of proposed experiments at GSI-FAIR. We find that perturbative corrections are large for both unpolarized and polarized cross sections, but that the spin asymmetries are stable. The role of the far infrared region of the momentum integral in the resummed exponent and the effect of the NNLL resummation are briefly discussed.

  15. Lower and upper estimates on the excitation threshold for breathers in discrete nonlinear Schroedinger lattices

    SciTech Connect (OSTI)

    Cuevas, J.; Palmero, F.

    2009-11-15

    We propose analytical lower and upper estimates on the excitation threshold for breathers (in the form of spatially localized and time periodic solutions) in discrete nonlinear Schroedinger (DNLS) lattices with power nonlinearity. The estimation, depending explicitly on the lattice parameters, is derived by a combination of a comparison argument on appropriate lower bounds depending on the frequency of each solution with a simple and justified heuristic argument. The numerical studies verify that the analytical estimates can be of particular usefulness, as a simple analytical detection of the activation energy for breathers in DNLS lattices.

  16. Reaction {pi}N {yields} {pi}{pi}N near threshold

    SciTech Connect (OSTI)

    Frlez, E.

    1993-11-01

    The LAMPF E1179 experiment used the {pi}{sup 0} spectrometer and an array of charged particle range counters to detect and record {pi}{sup +}{pi}{sup 0}, {pi}{sup 0}p, and {pi}{sup +}{pi}{sup 0}p coincidences following the reaction {pi}{sup +}p {yields} {pi}{sup 0}{pi}{sup +}p near threshold. The total cross sections for single pion production were measured at the incident pion kinetic energies 190, 200, 220, 240, and 260 MeV. Absolute normalizations were fixed by measuring {pi}{sup +}p elastic scattering at 260 MeV. A detailed analysis of the {pi}{sup 0} detection efficiency was performed using cosmic ray calibrations and pion single charge exchange measurements with a 30 MeV {pi}{sup {minus}} beam. All published data on {pi}N {yields} {pi}{pi}N, including our results, are simultaneously fitted to yield a common chiral symmetry breaking parameter {xi} ={minus}0.25{plus_minus}0.10. The threshold matrix element {vert_bar}{alpha}{sub 0}({pi}{sup 0}{pi}{sup +}p){vert_bar} determined by linear extrapolation yields the value of the s-wave isospin-2 {pi}{pi} scattering length {alpha}{sub 0}{sup 2}({pi}{pi}) = {minus}0.041{plus_minus}0.003 m{sub {pi}}{sup {minus}1}, within the framework of soft-pion theory.

  17. Blister Threshold Based Thermal Limits for the U-Mo Monolithic Fuel System

    SciTech Connect (OSTI)

    D. M. Wachs; I. Glagolenko; F. J. Rice; A. B. Robinson; B. H. Rabin; M. K. Meyer

    2012-10-01

    Fuel failure is most commonly induced in research and test reactor fuel elements by exposure to an under-cooled or over-power condition that results in the fuel temperature exceeding a critical threshold above which blisters form on the plate. These conditions can be triggered by normal operational transients (i.e. temperature overshoots that may occur during reactor startup or power shifts) or mild upset events (e.g., pump coastdown, small blockages, mis-loading of fuel elements into higher-than-planned power positions, etc.). The rise in temperature has a number of general impacts on the state of a fuel plate that include, for example, stress relaxation in the cladding (due to differential thermal expansion), softening of the cladding, increased mobility of fission gases, and increased fission-gas pressure in pores, all of which can encourage the formation of blisters on the fuel-plate surface. These blisters consist of raised regions on the surface of fuel plates that occur when the cladding plastically deforms in response to fission-gas pressure in large pores in the fuel meat and/or mechanical buckling of the cladding over damaged regions in the fuel meat. The blister temperature threshold decreases with irradiation because the mechanical properties of the fuel plate degrade while under irradiation (due to irradiation damage and fission-product accumulation) and because the fission-gas inventory progressively increases (and, thus, so does the gas pressure in pores).

  18. L to H mode transition: Parametric dependencies of the temperature threshold

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Bourdelle, C.; Chone, L.; Fedorczak, N.; Garbet, Xavier; Beyer, P.; Citrin, J.; Fuhr, G.; Loarte, A.; Maggi, C. F.; Militello, F.; et al

    2015-06-15

    The L to H mode transition occurs at a critical power which depends on various parameters, such as the magnetic field, the density, etc. Experimental evidence on various tokamaks (JET, ASDEX-Upgrade, DIII-D, Alcator C-Mod) points towards the existence of a critical temperature characterizing the transition. This criterion for the L-H transition is local and is therefore easier to be compared to theoretical approaches. In order to shed light on the mechanisms of the transition, simple theoretical ideas are used to derive a temperature threshold (Tth). They are based on the stabilization of the underlying turbulence by a mean radial electricmore » field shear. The nature of the turbulence varies as the collisionality decreases, from resistive ballooning modes to ion temperature gradient and trapped electron modes. The obtained parametric dependencies of the derived Tth are tested versus magnetic field, density, effective charge. Furthermore, various robust experimental observations are reproduced, in particular Tth increases with magnetic field B and increases with density below the density roll-over observed on the power threshold.« less

  19. Precision Measurement of the Spin-dependent Asymmetry in the Threshold Region of Quasielastic 3He

    SciTech Connect (OSTI)

    Feng Xiong

    2002-09-01

    The first precision measurement of the spin-dependent asymmetry in the threshold region of polarized {sup 3}He(polarized e, e') was carried out in Hall A at the Jefferson Laboratory, using a longitudinally polarized continuous electron beam incident on a high-pressure polarized {sup 3}He gas target. The polarized electron beam was generated by illuminating a strained GaAs cathode with high intensity circularly polarized laser light, and an average beam polarization of about 70% was achieved. The {sup 3}He target was polarized based on the principle of spin-exchange optical pumpint and the average target polarization was about 30%. The scattered electrons were detected in the two Hall A high resolution spectrometers, HRSe and HRSh. The data from HRSh were used for this analysis and covered both the elastic peak and the threshold region. Two kinematic points were measured in the threshold region, one with a central Q{sup 2}-value of 0.1 (GeV/c){sup 2} at an incident beam energy E{sub 0} = 0.778 GeV and the other with a central Q{sup 2}-value of 0.2 (GeV/c){sup 2} at E-0 = 1.727 GeV. The average beam current was 10 mu-A, which was mainly due to the limitation of the polarized {sup 3}He target. The measured asymmetry was compared with both plane wave impulse approximation (PWIA) calculations and non-relativistic full Faddeev calculations which include both final-state interactions (FSIs) and meson-exchange currents (MECs) effects. The poor description of the data by PWIA calculations at both Q{sup 2}-values suggests the existence of strong FSI and MEC effects in the threshold region of polarized {sup 3}He (polarized e, e'). Indeed, the agreement between the data and full calculations is very good at Q{sup 2} = 0.1 (GeV/c){sup 2}. On the other hand, a small discrepancy at Q{sup 2} = 0.2 (GeV/c){sup 2} is observed, which might be due to some Q{sup 2} -dependent effects such as relativity and three-nucleon forces (3NFs), which are not included in the framework of non

  20. Violations of Lorentz invariance in the neutrino sector: an improved analysis of anomalous threshold constraints

    SciTech Connect (OSTI)

    Maccione, Luca; Liberati, Stefano; Mattingly, David M. E-mail: liberati@sissa.it

    2013-03-01

    Recently there has been a renewed activity in the physics of violations of Lorentz invariance in the neutrino sector. Flavor dependent Lorentz violation, which generically changes the pattern of neutrino oscillations, is extremely tightly constrained by oscillation experiments. Flavor independent Lorentz violation, which does not introduce new oscillation phenomena, is much more weakly constrained with constraints coming from time of flight and anomalous threshold analyses. We use a simplified rotationally invariant model to investigate the effects of finite baselines and energy dependent dispersion on anomalous reaction rates in long baseline experiments and show numerically that anomalous reactions do not necessarily cut off the spectrum quite as sharply as currently assumed. We also present a revised analysis of how anomalous reactions can be used to cast constraints from the observed atmospheric high energy neutrinos and the expected cosmogenic ones.

  1. Φ-Meson Photoproduction with Linearly Polarized Photons at Threshold Energies

    SciTech Connect (OSTI)

    Salamanca, Julian; Cole, Philip L

    2007-10-01

    The observables provided by linearly-polarized photons are of interest in delineating the contributions of the various hadronic processes giving rise to vector meson photoproduction. In particular, we describe how Φ-meson production affords an incisive tool for exploring the nature of the parity exchange at threshold energies, the strangeness content of proton, as well as extracting signatures for the violation of Okubo-Zweig-Iizuka observation (OZI rule). Our goal is to study the γp → Φp reaction, with Φ → K+K-, in the photon energy range of 1.7 to 2.1 GeV by using the Coherent Linear Bremsstrahlung Facility in Hall B of Jefferson Laboratory, Newport News, VA. The data were collected during the g8b run in the summer of 2005.

  2. {phi}-Meson Photoproduction with Linearly Polarized Photons at Threshold Energies

    SciTech Connect (OSTI)

    Salamanca, Julian; Cole, Philip L.

    2007-10-26

    The observables provided by linearly-polarized photons are of interest in delineating the contributions of the various hadronic processes giving rise to vector meson photoproduction. In particular, we describe how {phi}-meson production affords an incisive tool for exploring the nature of the parity exchange at threshold energies, the strangeness content of proton, as well as extracting signatures for the violation of Okubo-Zweig-Iizuka observation (OZI rule). Our goal is to study the {gamma}-vectorp{yields}{phi}p reaction, with {phi}{yields}K{sup +}K{sup -}, in the photon energy range of 1.7 to 2.1 GeV by using the Coherent Linear Bremsstrahlung Facility in Hall B of Jefferson Laboratory, Newport News, VA. The data were collected during the g8b run in the summer of 2005.

  3. Graphene-doped polymer nanofibers for low-threshold nonlinear optical waveguiding

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Meng, Chao; Yu, Shao-Liang; Wang, Hong -Qing; Cao, Yue; Tong, Li -Min; Liu, Wei -Tao; Shen, Yuen -Ron

    2015-11-06

    Graphene-doped polymer nanofibers are fabricated by taper drawing of solvated polyvinyl alcohol doped with liquid-phase exfoliated graphene flakes. Nanofibers drawn this way typically have diameters measured in hundreds of nanometers and lengths in tens of millimeters; they show excellent uniformity and surface smoothness for optical waveguiding. Owing to their tightly confined waveguiding behavior, light–matter interaction in these subwavelength-diameter nanofibers is significantly enhanced. Using approximately 1350-nm-wavelength femto-second pulses, we demonstrate saturable absorption behavior in these nanofibers with a saturation threshold down to 0.25 pJ pulse-1 (peak power ~1.3 W). Additionally, using 1064-nm-wavelength nanosecond pulses as switching light, we show all-optical modulationmore » of a 1550-nm-wavelength signal light guided along a single nanofiber with a switching peak power of ~3.2 W.« less

  4. Magnetic Field Control of the NO{sub 2} Photodissociation Threshold

    SciTech Connect (OSTI)

    Jost, R.; Nygard, J.; Pasinski, A.; Delon, A. [Grenoble High Magnetic Field Laboratory, MPI FKF/CNRS, 25 Avenue des Martyrs, BP 166, 38042 Grenoble Cedex 9 (France)] [Grenoble High Magnetic Field Laboratory, MPI FKF/CNRS, 25 Avenue des Martyrs, BP 166, 38042 Grenoble Cedex 9 (France)

    1997-04-01

    This is the first experimental observation of the control of the dissociation energy of a polyatomic molecule with an external magnetic field. We have observed by laser-induced fluorescence that the NO{sub 2} photodissociation threshold is linearly lowered by a magnetic field. This effect reaches 13.2cm{sup -1} under 14T, i.e., 2{mu}{sub B}B. This result demonstrates that all the rovibronic levels of NO{sub 2} energetically above the lowest dissociation channel are significantly coupled, without any barrier, to the lowest exit channel: NO({sup 2}{Pi}{sub 1/2},v=0,J=1/2) and O({sup 3}P{sub 2},M{sub J}=-2). This simple behavior is explained by the existence of quantum chaos within the NO{sub 2} rovibronic levels. {copyright} {ital 1997} {ital The American Physical Society}

  5. MOA-2010-BLG-311: A PLANETARY CANDIDATE BELOW THE THRESHOLD OF RELIABLE DETECTION

    SciTech Connect (OSTI)

    Yee, J. C.; Hung, L.-W.; Gould, A.; Gaudi, B. S.; Bond, I. A.; Allen, W.; Monard, L. A. G.; Albrow, M. D.; Fouque, P.; Dominik, M.; Tsapras, Y.; Udalski, A.; Zellem, R.; Christie, G. W.; DePoy, D. L.; Dong, Subo; Drummond, J.; Gorbikov, E.; Han, C. E-mail: rzellem@lpl.arizona.edu; Collaboration: muFUN Collaboration; MOA Collaboration; OGLE Collaboration; PLANET Collaboration; RoboNet Collaboration; MiNDSTEp Consortium; and others

    2013-05-20

    We analyze MOA-2010-BLG-311, a high magnification (A{sub max} > 600) microlensing event with complete data coverage over the peak, making it very sensitive to planetary signals. We fit this event with both a point lens and a two-body lens model and find that the two-body lens model is a better fit but with only {Delta}{chi}{sup 2} {approx} 80. The preferred mass ratio between the lens star and its companion is q = 10{sup -3.7{+-}0.1}, placing the candidate companion in the planetary regime. Despite the formal significance of the planet, we show that because of systematics in the data the evidence for a planetary companion to the lens is too tenuous to claim a secure detection. When combined with analyses of other high-magnification events, this event helps empirically define the threshold for reliable planet detection in high-magnification events, which remains an open question.

  6. Graphene-doped polymer nanofibers for low-threshold nonlinear optical waveguiding

    SciTech Connect (OSTI)

    Meng, Chao; Yu, Shao-Liang; Wang, Hong -Qing; Cao, Yue; Tong, Li -Min; Liu, Wei -Tao; Shen, Yuen -Ron

    2015-11-06

    Graphene-doped polymer nanofibers are fabricated by taper drawing of solvated polyvinyl alcohol doped with liquid-phase exfoliated graphene flakes. Nanofibers drawn this way typically have diameters measured in hundreds of nanometers and lengths in tens of millimeters; they show excellent uniformity and surface smoothness for optical waveguiding. Owing to their tightly confined waveguiding behavior, light–matter interaction in these subwavelength-diameter nanofibers is significantly enhanced. Using approximately 1350-nm-wavelength femto-second pulses, we demonstrate saturable absorption behavior in these nanofibers with a saturation threshold down to 0.25 pJ pulse-1 (peak power ~1.3 W). Additionally, using 1064-nm-wavelength nanosecond pulses as switching light, we show all-optical modulation of a 1550-nm-wavelength signal light guided along a single nanofiber with a switching peak power of ~3.2 W.

  7. Ablation experiment and threshold calculation of titanium alloy irradiated by ultra-fast pulse laser

    SciTech Connect (OSTI)

    Zheng, Buxiang; Jiang, Gedong; Wang, Wenjun Wang, Kedian; Mei, Xuesong; State Key Laboratory for Manufacturing Systems Engineering, Xi'an Jiaotong University, Xi'an 710054

    2014-03-15

    The interaction between an ultra-fast pulse laser and a material's surface has become a research hotspot in recent years. Micromachining of titanium alloy with an ultra-fast pulse laser is a very important research direction, and it has very important theoretical significance and application value in investigating the ablation threshold of titanium alloy irradiated by ultra-fast pulse lasers. Irradiated by a picosecond pulse laser with wavelengths of 1064 nm and 532 nm, the surface morphology and feature sizes, including ablation crater width (i.e. diameter), ablation depth, ablation area, ablation volume, single pulse ablation rate, and so forth, of the titanium alloy were studied, and their ablation distributions were obtained. The experimental results show that titanium alloy irradiated by a picosecond pulse infrared laser with a 1064 nm wavelength has better ablation morphology than that of the green picosecond pulse laser with a 532 nm wavelength. The feature sizes are approximately linearly dependent on the laser pulse energy density at low energy density and the monotonic increase in laser pulse energy density. With the increase in energy density, the ablation feature sizes are increased. The rate of increase in the feature sizes slows down gradually once the energy density reaches a certain value, and gradually saturated trends occur at a relatively high energy density. Based on the linear relation between the laser pulse energy density and the crater area of the titanium alloy surface, and the Gaussian distribution of the laser intensity on the cross section, the ablation threshold of titanium alloy irradiated by an ultra-fast pulse laser was calculated to be about 0.109 J/cm{sup 2}.

  8. Direct Measurements of an increased threshold for stimulated Brillouin scattering with polarization smoothing in ignition hohlraum plasmas

    SciTech Connect (OSTI)

    Froula, D; Divol, L; Berger, R L; London, R; Meezan, N; Neumayer, P; Ross, J S; Stagnito, S; Suter, L; Glenzer, S H; Strozzi, D

    2007-11-08

    We demonstrate a significant reduction of stimulated Brillouin scattering by polarization smoothing. The intensity threshold is measured to increase by a factor of 1.7 {+-} 0.2 when polarization smoothing is applied. The results were obtained in a high-temperature (T{sub 3} {approx_equal} 3 keV) hohlraum plasma where filamentation is negligible in determining the backscatter threshold. These results are explained by an analytical model relevant to ICF plasma conditions that modifies the linear gain exponent to account for polarization smoothing.

  9. Impact of different cleaning processes on the laser damage threshold of antireflection coatings for Z-Backlighter optics at Sandia National Laboratories

    SciTech Connect (OSTI)

    Field, Ella; Bellum, John; Kletecka, Damon

    2014-11-06

    We have examined how different cleaning processes affect the laser-induced damage threshold of antireflection coatings for large dimension, Z-Backlighter laser optics at Sandia National Laboratories. Laser damage thresholds were measured after the coatings were created, and again 4 months later to determine which cleaning processes were most effective. There is a nearly twofold increase in laser-induced damage threshold between the antireflection coatings that were cleaned and those that were not cleaned. Aging of the coatings after 4 months resulted in even higher laser-induced damage thresholds. Also, the laser-induced damage threshold results revealed that every antireflection coating had a high defect density, despite the cleaning process used, which indicates that improvements to either the cleaning or deposition processes should provide even higher laser-induced damage thresholds.

  10. Impact of different cleaning processes on the laser damage threshold of antireflection coatings for Z-Backlighter optics at Sandia National Laboratories

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Field, Ella; Bellum, John; Kletecka, Damon

    2014-11-06

    We have examined how different cleaning processes affect the laser-induced damage threshold of antireflection coatings for large dimension, Z-Backlighter laser optics at Sandia National Laboratories. Laser damage thresholds were measured after the coatings were created, and again 4 months later to determine which cleaning processes were most effective. There is a nearly twofold increase in laser-induced damage threshold between the antireflection coatings that were cleaned and those that were not cleaned. Aging of the coatings after 4 months resulted in even higher laser-induced damage thresholds. Also, the laser-induced damage threshold results revealed that every antireflection coating had a high defectmore » density, despite the cleaning process used, which indicates that improvements to either the cleaning or deposition processes should provide even higher laser-induced damage thresholds.« less

  11. Development of CDMS-II Surface Event Rejection Techniques and Their Extensions to Lower Energy Thresholds

    SciTech Connect (OSTI)

    Hofer, Thomas James

    2014-12-01

    The CDMS-II phase of the Cryogenic Dark Matter Search, a dark matter direct-detection experiment, was operated at the Soudan Underground Laboratory from 2003 to 2008. The full payload consisted of 30 ZIP detectors, totaling approximately 1.1 kg of Si and 4.8 kg of Ge, operated at temperatures of 50 mK. The ZIP detectors read out both ionization and phonon pulses from scatters within the crystals; channel segmentation and analysis of pulse timing parameters allowed e ective ducialization of the crystal volumes and background rejection su cient to set world-leading limits at the times of their publications. A full re-analysis of the CDMS-II data was motivated by an improvement in the event reconstruction algorithms which improved the resolution of ionization energy and timing information. The Ge data were re-analyzed using three distinct background-rejection techniques; the Si data from runs 125 - 128 were analyzed for the rst time using the most successful of the techniques from the Ge re-analysis. The results of these analyses prompted a novel \\mid-threshold" analysis, wherein energy thresholds were lowered but background rejection using phonon timing information was still maintained. This technique proved to have signi cant discrimination power, maintaining adequate signal acceptance and minimizing background leakage. The primary background for CDMS-II analyses comes from surface events, whose poor ionization collection make them di cult to distinguish from true nuclear recoil events. The novel detector technology of SuperCDMS, the successor to CDMS-II, uses interleaved electrodes to achieve full ionization collection for events occurring at the top and bottom detector surfaces. This, along with dual-sided ionization and phonon instrumentation, allows for excellent ducialization and relegates the surface-event rejection techniques of CDMS-II to a secondary level of background discrimination. Current and future SuperCDMS results hold great promise for mid- to low

  12. Image registration method for medical image sequences

    SciTech Connect (OSTI)

    Gee, Timothy F.; Goddard, James S.

    2013-03-26

    Image registration of low contrast image sequences is provided. In one aspect, a desired region of an image is automatically segmented and only the desired region is registered. Active contours and adaptive thresholding of intensity or edge information may be used to segment the desired regions. A transform function is defined to register the segmented region, and sub-pixel information may be determined using one or more interpolation methods.

  13. Damage Threshold of Platinum Coating used for Optics for Self-Seeding of Soft X-ray Free Electron Laser

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Krzywinski, Jacek; Cocco, Daniele; Moeller, Stefan; Ratner, Daniel

    2015-02-23

    We investigated the experimental damage threshold of platinum coating on a silicon substrate illuminated by soft x-ray radiation at grazing incidence angle of 2.1 deg. The coating was the same as the blazed grating used for the soft X-ray self-seeding optics of the Linac Coherent Light Source free electron laser. The irradiation condition was chosen such that the absorbed dose was similar to the maximum dose expected for the grating. The expected dose was simulated by solving the Helmholtz equation in non-homogenous media. The experiment was performed at 900 eV photon energy for both single pulse and multi-shot conditions. Wemorehave not observed single shot damage. This corresponds to a single shot damage threshold being higher than 3 J/cm2. The multiple shot damage threshold measured for 10 shots and about 600 shots was determined to be 0.95 J/cm2 and 0.75 J/cm2 respectively. The damage threshold occurred at an instantaneous dose which is higher that the melt dose of platinum.less

  14. Sensitivity of the threshold voltage of organic thin-film transistors to light and water

    SciTech Connect (OSTI)

    Feng, Cong; Marinov, Ognian; Deen, M. Jamal; Selvaganapathy, Ponnambalam Ravi; Wu, Yiliang

    2015-05-14

    Analyses of extensive experiments with organic thin-film transistors (OTFTs) indicate that the threshold voltage V{sub T} of an OTFT has a temporal differential sensitivity. In particular, V{sub T} changes initially by changing the light illumination intensity or making/removing a contact of water with the organic semiconductor. Keeping the conditions stationary, then the initial shift of V{sub T} diminishes, since the time dependence of V{sub T} gradually recovers the OTFT to the state before applying the change in the environmental conditions. While still causing a differential and time-variant shift of V{sub T}, the deionized water does not have a dramatic impact on OTFTs that use the polymer DKPP-?T (diketopyrrolopyrrole ?-unsubstituted quaterthiophene) as the active semiconductor material. Observations for the impact of water are made from experiments with an OTFT that has a microfluidic channel on the top the electrical channel, with the water in the microfluidic channel in direct contact with the electrical channel of the OTFT. This arrangement of electrical and microfluidic channels is a novel structure of the microfluidic OTFT, suitable for sensing applications of liquid analytes by means of organic electronics.

  15. A threshold gas Cerenkov detector for the spin asymmetries of the nucleon experiment

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Armstrong, Whitney R.; Choi, Seonho; Kaczanowicz, Ed; Lukhanin, Alexander; Meziani, Zein -Eddine; Sawatzky, Brad D.

    2015-09-26

    In this study, we report on the design, construction, commissioning, and performance of a threshold gas Cerenkov counter in an open configuration, which operates in a high luminosity environment and produces a high photo-electron yield. Part of a unique open geometry detector package known as the Big Electron Telescope Array, this Cerenkov counter served to identify scattered electrons and reject produced pions in an inclusive scattering experiment known as the Spin Asymmetries of the Nucleon Experiment E07-003 at the Thomas Jefferson National Accelerator Facility (TJNAF) also known as Jefferson Lab. The experiment consisted of a measurement of double spin asymmetriesmore » A|| and A⊥ of a polarized electron beam impinging on a polarized ammonia target. The Cerenkov counter's performance is characterised by a yield of about 20 photoelectrons per electron or positron track. Thanks to this large number of photoelectrons per track, the Cerenkov counter had enough resolution to identify electron-positron pairs from the conversion of photons resulting mainly from π0 decays.« less

  16. Reprogrammable read only variable threshold transistor memory with isolated addressing buffer

    DOE Patents [OSTI]

    Lodi, Robert J.

    1976-01-01

    A monolithic integrated circuit, fully decoded memory comprises a rectangular array of variable threshold field effect transistors organized into a plurality of multi-bit words. Binary address inputs to the memory are decoded by a field effect transistor decoder into a plurality of word selection lines each of which activates an address buffer circuit. Each address buffer circuit, in turn, drives a word line of the memory array. In accordance with the word line selected by the decoder the activated buffer circuit directs reading or writing voltages to the transistors comprising the memory words. All of the buffer circuits additionally are connected to a common terminal for clearing all of the memory transistors to a predetermined state by the application to the common terminal of a large magnitude voltage of a predetermined polarity. The address decoder, the buffer and the memory array, as well as control and input/output control and buffer field effect transistor circuits, are fabricated on a common substrate with means provided to isolate the substrate of the address buffer transistors from the remainder of the substrate so that the bulk clearing function of simultaneously placing all of the memory transistors into a predetermined state can be performed.

  17. A threshold gas Cerenkov detector for the spin asymmetries of the nucleon experiment

    SciTech Connect (OSTI)

    Armstrong, Whitney R.; Choi, Seonho; Kaczanowicz, Ed; Lukhanin, Alexander; Meziani, Zein -Eddine; Sawatzky, Brad D.

    2015-09-26

    In this study, we report on the design, construction, commissioning, and performance of a threshold gas Cerenkov counter in an open configuration, which operates in a high luminosity environment and produces a high photo-electron yield. Part of a unique open geometry detector package known as the Big Electron Telescope Array, this Cerenkov counter served to identify scattered electrons and reject produced pions in an inclusive scattering experiment known as the Spin Asymmetries of the Nucleon Experiment E07-003 at the Thomas Jefferson National Accelerator Facility (TJNAF) also known as Jefferson Lab. The experiment consisted of a measurement of double spin asymmetries A|| and A? of a polarized electron beam impinging on a polarized ammonia target. The Cerenkov counter's performance is characterised by a yield of about 20 photoelectrons per electron or positron track. Thanks to this large number of photoelectrons per track, the Cerenkov counter had enough resolution to identify electron-positron pairs from the conversion of photons resulting mainly from ?0 decays.

  18. Coherent ?{sup 0}-photoproduction on the deuteron near the ?-production threshold including polarization observables

    SciTech Connect (OSTI)

    Darwish, Eed M.; Al-Thoyaib, Suleiman S.

    2014-12-15

    Coherent ?{sup 0}-photoproduction on the deuteron including polarization observables is studied in the energy region near the ?-production threshold at backward center-of-mass angles of the outgoing pion. This work is motivated by the measurements of the CLAS Collaboration at Jefferson Lab, where a cusp-like structure in the energy dependence of the differential cross section has been observed at extremely backward pion angles. The present approach is based on the impulse approximation and first-order rescattering diagrams with intermediate production of both ?- and ?-mesons. Numerical results for unpolarized cross sections, the linear photon asymmetry (?), the vector (T{sub 11}) and tensor (T{sub 2M}, M=0, 1, 2) deuteron target asymmetries, and the double polarization E-asymmetry are predicted and compared with available experimental data and other theoretical models. The effect of first-order rescattering is found to be much larger in spin asymmetries than in the unpolarized cross sections. It reaches on average about 40% in the tensor target and E asymmetries. Compared to the experimental data from CLAS Collaboration, sizable discrepancies are found. This is not the case for the linear photon asymmetry, for which a better comparison with the data from YerPhI Collaboration is obtained.

  19. Method for improving instrument response

    DOE Patents [OSTI]

    Hahn, David W.; Hencken, Kenneth R.; Johnsen, Howard A.; Flower, William L.

    2000-01-01

    This invention pertains generally to a method for improving the accuracy of particle analysis under conditions of discrete particle loading and particularly to a method for improving signal-to-noise ratio and instrument response in laser spark spectroscopic analysis of particulate emissions. Under conditions of low particle density loading (particles/m.sup.3) resulting from low overall metal concentrations and/or large particle size uniform sampling can not be guaranteed. The present invention discloses a technique for separating laser sparks that arise from sample particles from those that do not; that is, a process for systematically "gating" the instrument response arising from "sampled" particles from those responses which do not, is dislosed as a solution to his problem. The disclosed approach is based on random sampling combined with a conditional analysis of each pulse. A threshold value is determined for the ratio of the intensity of a spectral line for a given element to a baseline region. If the threshold value is exceeded, the pulse is classified as a "hit" and that data is collected and an average spectrum is generated from an arithmetic average of "hits". The true metal concentration is determined from the averaged spectrum.

  20. Method and apparatus for analog pulse pile-up rejection

    DOE Patents [OSTI]

    De Geronimo, Gianluigi

    2014-11-18

    A method and apparatus for pulse pile-up rejection are disclosed. The apparatus comprises a delay value application constituent configured to receive a threshold-crossing time value, and provide an adjustable value according to a delay value and the threshold-crossing time value; and a comparison constituent configured to receive a peak-occurrence time value and the adjustable value, compare the peak-occurrence time value with the adjustable value, indicate pulse acceptance if the peak-occurrence time value is less than or equal to the adjustable value, and indicate pulse rejection if the peak-occurrence time value is greater than the adjustable value.

  1. Method and apparatus for analog pulse pile-up rejection

    DOE Patents [OSTI]

    De Geronimo, Gianluigi

    2013-12-31

    A method and apparatus for pulse pile-up rejection are disclosed. The apparatus comprises a delay value application constituent configured to receive a threshold-crossing time value, and provide an adjustable value according to a delay value and the threshold-crossing time value; and a comparison constituent configured to receive a peak-occurrence time value and the adjustable value, compare the peak-occurrence time value with the adjustable value, indicate pulse acceptance if the peak-occurrence time value is less than or equal to the adjustable value, and indicate pulse rejection if the peak-occurrence time value is greater than the adjustable value.

  2. Methods, apparatus and system for selective duplication of subtasks

    DOE Patents [OSTI]

    Andrade Costa, Carlos H.; Cher, Chen-Yong; Park, Yoonho; Rosenburg, Bryan S.; Ryu, Kyung D.

    2016-03-29

    A method for selective duplication of subtasks in a high-performance computing system includes: monitoring a health status of one or more nodes in a high-performance computing system, where one or more subtasks of a parallel task execute on the one or more nodes; identifying one or more nodes as having a likelihood of failure which exceeds a first prescribed threshold; selectively duplicating the one or more subtasks that execute on the one or more nodes having a likelihood of failure which exceeds the first prescribed threshold; and notifying a messaging library that one or more subtasks were duplicated.

  3. e08-008: Exclusive study of deuteron electrodisintegration near threshold

    SciTech Connect (OSTI)

    Hanretty, C.

    2014-01-01

    The study of threshold electrodisintegration of and elastic scattering on the only stable two nucleon system, the deuteron, can reveal specific aspects of the N-N interaction. The simplicity of electrodisintegration along with the simplicity of the deuteron makes this study most appropriate for revealing these interactions. By using an incident beam of polarized electrons and by measuring the polarization of the recoiling proton, the ratio of the electric (G{sub E} ) and magnetic (G{sub M} ) form factors for d((vector e),e'(vector p)) (and p((vector e) ,e'(vector p))) reactions may be extracted. This experiment was conducted in Hall A at Jefferson Lab in Newport News, Virginia using a beam of polarized electrons provided by the CEBAF Accelerator incident on a liquid deuterium (and hydrogen) target. The scattered electron and the recoiling (polarized) proton were detected using the High Resolution Spectrometers of Hall A. To determine the polarization of the recoil proton, an analyzing material was placed perpendicular to the protons trajectory through the spectrometer, in front of a set of straw chambers. Due to the spin-orbit interactions involved in the scattering of the proton from the analyzer material, asymmetries seen in the distribution of events detected by these straw chambers reveal the polarization of the recoil proton. By tracking the spin procession of the polarized protons from the straw chambers back to the target, the transferred and induced polarization of the proton may be determined. The (double-spin) asymmetries observed in the straw chambers will first be studied for the well-known elastic p((vector e), e'(vector p)) process and compared to the asymmetries for d((vector e),e'(vector p))n(x{sub B}=1) . The analysis will then be repeated to determine how these asymmetries change with increasing x{sub B} (to the kinematic limit for deuteron electrodisintegration).

  4. Lead-chalcogenide mid-infrared vertical external cavity surface emitting lasers with improved threshold: Theory and experiment

    SciTech Connect (OSTI)

    Fill, Matthias; Phocone AG, 8005 Zurich ; Debernardi, Pierluigi; Felder, Ferdinand; Zogg, Hans

    2013-11-11

    Mid-infrared Vertical External Cavity Surface Emitting Lasers (VECSEL) based on narrow gap lead-chalcogenide (IV-VI) semiconductors exhibit strongly reduced threshold powers if the active layers are structured laterally for improved optical confinement. This is predicted by 3-d optical calculations; they show that lateral optical confinement is needed to counteract the anti-guiding features of IV-VIs due to their negative temperature dependence of the refractive index. An experimental proof is performed with PbSe quantum well based VECSEL grown on a Si-substrate by molecular beam epitaxy and emitting around 3.3 μm. With proper mesa-etching, the threshold intensity is about 8-times reduced.

  5. Recovery from ultraviolet-induced threshold voltage shift in indium gallium zinc oxide thin film transistors by positive gate bias

    SciTech Connect (OSTI)

    Liu, P.; Chen, T. P.; Li, X. D.; Wong, J. I.; Liu, Z.; Liu, Y.; Leong, K. C.

    2013-11-11

    The effect of short-duration ultraviolet (UV) exposure on the threshold voltage (V{sub th}) of amorphous indium gallium zinc oxide thin film transistors (TFTs) and its recovery characteristics were investigated. The V{sub th} exhibited a significant negative shift after UV exposure. The V{sub th} instability caused by UV illumination is attributed to the positive charge trapping in the dielectric layer and/or at the channel/dielectric interface. The illuminated devices showed a slow recovery in threshold voltage without external bias. However, an instant recovery can be achieved by the application of positive gate pulses, which is due to the elimination of the positive trapped charges as a result of the presence of a large amount of field-induced electrons in the interface region.

  6. On Baryon-Antibaryon Cross Sections from Initial State Radiation Processes at BABAR and their Surprising Threshold Behavior

    SciTech Connect (OSTI)

    Pacetti, Simone

    2015-04-14

    BABAR has measured with unprecedented accuracy the e+e- → pp-bar and e+e- → ΛΛ-bar cross sections by means of the initial state radiation technique, which has the advantages of good efficiency and energy resolution, and full angular acceptance in the threshold region. A striking feature of these cross sections is their non-vanishing values at threshold. In the case of charged baryons, the phenomenon is well understood in terms of the Coulomb interaction between the outgoing baryon and antibaryon. However, such an effect is not expected for neutral baryons. We suggest a simple explanation for both charged and neutral baryon pairs based on Coulomb interactions at the valence quark level.

  7. Exotic Effects at the Charm Threshold and Other Novel Physics Topics at JLab-12 GeV

    SciTech Connect (OSTI)

    Brodsky, Stanley J.; /SLAC

    2012-05-03

    I briefly survey a number of novel hadron physics topics which can be investigated with the 12 GeV upgrade at J-Lab. The topics include new the formation of exotic heavy quark resonances accessible above the charm threshold, intrinsic charm and strangeness phenomena, the exclusive Sivers effect, hidden-color Fock states of nuclei, local two-photon interactions in deeply virtual Compton scattering, and non-universal antishadowing.

  8. Study of small carbon and semiconductor clusters using negative ion threshold photodetachment spectroscopy

    SciTech Connect (OSTI)

    Arnold, C.C.

    1994-08-01

    The bonding and electronics of several small carbon and semiconductor clusters containing less than ten atoms are probed using negative ion threshold photodetachment (zero electron kinetic energy, or ZEKE) spectroscopy. ZEKE spectroscopy is a particularly advantageous technique for small cluster study, as it combines mass selection with good spectroscopic resolution. The ground and low-lying electronic states of small clusters in general can be accessed by detaching an electron from the ground anion state. The clusters studied using this technique and described in this work are C{sub 6}{sup {minus}}/C{sub 6}, Si{sub n}{sup {minus}}/Si{sub n} (n = 2, 3, 4), Ge{sub 2}{sup {minus}}/Ge{sub 2}, In{sub 2}P{sup {minus}}/In{sub 2}P,InP{sub 2}{sup {minus}}/InP{sup 2}, and Ga{sub 2}As{sup {minus}}. The total photodetachment cross sections of several other small carbon clusters and the ZEKE spectrum of the I{sup {minus}}{center_dot}CH{sub 3}I S{sub N}2 reaction complex are also presented to illustrate the versatility of the experimental apparatus. Clusters with so few atoms do not exhibit bulk properties. However, each specie exhibits bonding properties that relate to the type of bonding found in the bulk. C{sub 6}, as has been predicted, exhibits a linear cumulenic structure, where double bonds connect all six carbon atoms. This double bonding reflects how important {pi} bonding is in certain phases of pure carbon (graphite and fullerenes). The symmetric stretch frequencies observed in the C{sub 6}{sup {minus}} spectra, however, are in poor agreement with the calculated values. Also observed as sharp structure in total photodetachment cross section scans was an excited anion state bound by only {approximately}40 cm{sup {minus}1} relative to the detachment continuum. This excited anion state appears to be a valence bound state, possible because of the high electron affinity of C{sub 6}, and the open shell of the anion.

  9. Discontinuous non-equilibrium phase transition in a threshold Schloegl model for autocatalysis: Generic two-phase coexistence and metastability

    SciTech Connect (OSTI)

    Wang, Chi -Jen; Liu, Da -Jiang; Evans, James W.

    2015-04-28

    Threshold versions of Schloegl’s model on a lattice, which involve autocatalytic creation and spontaneous annihilation of particles, can provide a simple prototype for discontinuous non-equilibrium phase transitions. These models are equivalent to so-called threshold contact processes. A discontinuous transition between populated and vacuum states can occur selecting a threshold of N ≥ 2 for the minimum number, N, of neighboring particles enabling autocatalytic creation at an empty site. Fundamental open questions remain given the lack of a thermodynamic framework for analysis. For a square lattice with N = 2, we show that phase coexistence occurs not at a unique value but for a finite range of particle annihilation rate (the natural control parameter). This generic two-phase coexistence also persists when perturbing the model to allow spontaneous particle creation. Such behavior contrasts both the Gibbs phase rule for thermodynamic systems and also previous analysis for this model. We find metastability near the transition corresponding to a non-zero effective line tension, also contrasting previously suggested critical behavior. As a result, mean-field type analysis, extended to treat spatially heterogeneous states, further elucidates model behavior.

  10. Discontinuous non-equilibrium phase transition in a threshold Schloegl model for autocatalysis: Generic two-phase coexistence and metastability

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Wang, Chi -Jen; Liu, Da -Jiang; Evans, James W.

    2015-04-28

    Threshold versions of Schloegl’s model on a lattice, which involve autocatalytic creation and spontaneous annihilation of particles, can provide a simple prototype for discontinuous non-equilibrium phase transitions. These models are equivalent to so-called threshold contact processes. A discontinuous transition between populated and vacuum states can occur selecting a threshold of N ≥ 2 for the minimum number, N, of neighboring particles enabling autocatalytic creation at an empty site. Fundamental open questions remain given the lack of a thermodynamic framework for analysis. For a square lattice with N = 2, we show that phase coexistence occurs not at a unique valuemore » but for a finite range of particle annihilation rate (the natural control parameter). This generic two-phase coexistence also persists when perturbing the model to allow spontaneous particle creation. Such behavior contrasts both the Gibbs phase rule for thermodynamic systems and also previous analysis for this model. We find metastability near the transition corresponding to a non-zero effective line tension, also contrasting previously suggested critical behavior. As a result, mean-field type analysis, extended to treat spatially heterogeneous states, further elucidates model behavior.« less

  11. Molecular-beam epitaxy of heterostructures of wide-gap II–VI compounds for low-threshold lasers with optical and electron pumping

    SciTech Connect (OSTI)

    Sorokin, S. V. Gronin, S. V.; Sedova, I. V.; Rakhlin, M. V.; Baidakova, M. V.; Kop’ev, P. S.; Vainilovich, A. G.; Lutsenko, E. V.; Yablonskii, G. P.; Gamov, N. A.; Zhdanova, E. V.; Zverev, M. M.; Ruvimov, S. S.; Ivanov, S. V.

    2015-03-15

    The paper presents basic approaches in designing and growing by molecular beam epitaxy of (Zn,Mg)(S,Se)-based laser heterostructures with multiple CdSe quantum dot (QD) sheets or ZnCdSe quantum wells (QW). The method of calculation of compensating short-period ZnSSe/ZnSe superlattices (SLs) in both active and waveguide regions of laser heterostructures possessing the different waveguide thickness and different number of active regions is presented. The method allowing reduction of the density of nonequilibrium point defects in the active region of the II–VI laser structures has been proposed. It utilizes the migration enhanced epitaxy mode in growing the ZnSe QW confining the CdSe QD sheet. The threshold power density as low as P{sub thr} ∼ 0.8 kW/cm{sup 2} at T = 300 K has been demonstrated for laser heterostructure with single CdSe QD sheet and asymmetric graded-index waveguide with strain-compensating SLs.

  12. Correlation methods

    SciTech Connect (OSTI)

    Balcomb, J.D.

    1981-01-01

    Correlation methods have been developed to provide a quick and relatively simple technique for estimating the performance of passive solar systems. The correlations are done with respect to data generated from simulation models. The techniques and accuracies are described. Both the Solar Load Ratio and Un-Utilizability methods are described. The advantages and limitations of correlation methods as design tools are discussed.

  13. Method for microbeam radiation therapy

    DOE Patents [OSTI]

    Slatkin, Daniel N.; Dilmanian, F. Avraham; Spanne, Per O.

    1994-01-01

    A method of performing radiation therapy on a patient, involving exposing a target, usually a tumor, to a therapeutic dose of high energy electromagnetic radiation, preferably X-ray radiation, in the form of at least two non-overlapping microbeams of radiation, each microbeam having a width of less than about 1 millimeter. Target tissue exposed to the microbeams receives a radiation dose during the exposure that exceeds the maximum dose that such tissue can survive. Non-target tissue between the microbeams receives a dose of radiation below the threshold amount of radiation that can be survived by the tissue, and thereby permits the non-target tissue to regenerate. The microbeams may be directed at the target from one direction, or from more than one direction in which case the microbeams overlap within the target tissue enhancing the lethal effect of the irradiation while sparing the surrounding healthy tissue.

  14. Method for microbeam radiation therapy

    DOE Patents [OSTI]

    Slatkin, D.N.; Dilmanian, F.A.; Spanne, P.O.

    1994-08-16

    A method is disclosed of performing radiation therapy on a patient, involving exposing a target, usually a tumor, to a therapeutic dose of high energy electromagnetic radiation, preferably X-ray radiation. The dose is in the form of at least two non-overlapping microbeams of radiation, each microbeam having a width of less than about 1 millimeter. Target tissue exposed to the microbeams receives a radiation dose during the exposure that exceeds the maximum dose that such tissue can survive. Non-target tissue between the microbeams receives a dose of radiation below the threshold amount of radiation that can be survived by the tissue, and thereby permits the non-target tissue to regenerate. The microbeams may be directed at the target from one direction, or from more than one direction in which case the microbeams overlap within the target tissue enhancing the lethal effect of the irradiation while sparing the surrounding healthy tissue. No Drawings

  15. A Cluster-based Method to Map Urban Area from DMSP/OLS Nightlights

    SciTech Connect (OSTI)

    Zhou, Yuyu; Smith, Steven J.; Elvidge, Christopher; Zhao, Kaiguang; Thomson, Allison M.; Imhoff, Marc L.

    2014-05-05

    Accurate information of urban areas at regional and global scales is important for both the science and policy-making communities. The Defense Meteorological Satellite Program/Operational Linescan System (DMSP/OLS) nighttime stable light data (NTL) provide a potential way to map urban area and its dynamics economically and timely. In this study, we developed a cluster-based method to estimate the optimal thresholds and map urban extents from the DMSP/OLS NTL data in five major steps, including data preprocessing, urban cluster segmentation, logistic model development, threshold estimation, and urban extent delineation. Different from previous fixed threshold method with over- and under-estimation issues, in our method the optimal thresholds are estimated based on cluster size and overall nightlight magnitude in the cluster, and they vary with clusters. Two large countries of United States and China with different urbanization patterns were selected to map urban extents using the proposed method. The result indicates that the urbanized area occupies about 2% of total land area in the US ranging from lower than 0.5% to higher than 10% at the state level, and less than 1% in China, ranging from lower than 0.1% to about 5% at the province level with some municipalities as high as 10%. The derived thresholds and urban extents were evaluated using high-resolution land cover data at the cluster and regional levels. It was found that our method can map urban area in both countries efficiently and accurately. Compared to previous threshold techniques, our method reduces the over- and under-estimation issues, when mapping urban extent over a large area. More important, our method shows its potential to map global urban extents and temporal dynamics using the DMSP/OLS NTL data in a timely, cost-effective way.

  16. Connection method

    DOE Patents [OSTI]

    Weyand, J.D.

    1986-11-18

    A method is disclosed of making a region exhibiting a range of compositions, comprising plasma spraying various compositions on top of one another onto a base. 2 figs.

  17. Connection method

    DOE Patents [OSTI]

    Weyand, John D.

    1986-01-01

    A method of making a region exhibiting a range of compositions, comprising plasma spraying various compositions on top of one another onto a base.

  18. An Approach to Industrial Stormwater Benchmarks: Establishing and Using Site-Specific Threshold Criteria at Lawrence Livermore National Laboratory

    SciTech Connect (OSTI)

    Campbell, C G; Mathews, S

    2006-09-07

    Current regulatory schemes use generic or industrial sector specific benchmarks to evaluate the quality of industrial stormwater discharges. While benchmarks can be a useful tool for facility stormwater managers in evaluating the quality stormwater runoff, benchmarks typically do not take into account site-specific conditions, such as: soil chemistry, atmospheric deposition, seasonal changes in water source, and upstream land use. Failing to account for these factors may lead to unnecessary costs to trace a source of natural variation, or potentially missing a significant local water quality problem. Site-specific water quality thresholds, established upon the statistical evaluation of historic data take into account these factors, are a better tool for the direct evaluation of runoff quality, and a more cost-effective trigger to investigate anomalous results. Lawrence Livermore National Laboratory (LLNL), a federal facility, established stormwater monitoring programs to comply with the requirements of the industrial stormwater permit and Department of Energy orders, which require the evaluation of the impact of effluent discharges on the environment. LLNL recognized the need to create a tool to evaluate and manage stormwater quality that would allow analysts to identify trends in stormwater quality and recognize anomalous results so that trace-back and corrective actions could be initiated. LLNL created the site-specific water quality threshold tool to better understand the nature of the stormwater influent and effluent, to establish a technical basis for determining when facility operations might be impacting the quality of stormwater discharges, and to provide ''action levels'' to initiate follow-up to analytical results. The threshold criteria were based on a statistical analysis of the historic stormwater monitoring data and a review of relevant water quality objectives.

  19. {sup 16}O resonances near 4? threshold through {sup 12}C({sup 6}Li,d) reaction

    SciTech Connect (OSTI)

    Rodrigues, M. R. D.; Borello-Lewin, T.; Miyake, H.; Horodynski-Matsushigue, L. B.; Duarte, J. L. M.; Rodrigues, C. L.; Faria, P. Neto de; Cunsolo, A.; Cappuzzello, F.; Foti, A.; Agodi, C.; Cavallaro, M.; Napoli, M. di; Ukita, G. M.

    2014-11-11

    Several narrow alpha resonant {sup 16}O states were detected through the {sup 12}C({sup 6}Li,d) reaction, in the range of 13.5 to 17.5 MeV of excitation energy. The reaction was measured at a bombarding energy of 25.5 MeV employing the So Paulo Pelletron-Enge-Spectrograph facility and the nuclear emulsion technique. Experimental angular distributions associated with natural parity quasi-bound states around the 4? threshold are presented and compared to DWBA predictions. The upper limit for the resonance widths obtained is near the energy resolution (15 keV)

  20. Resonance {eta} Prime -meson photoproduction on protons at photon energies from the reaction threshold to 3700 MeV

    SciTech Connect (OSTI)

    Tryasuchev, V. A.

    2013-06-15

    The parameters of six resonances of the isobar model for {eta} Prime -meson photoproduction were fitted to experimental differential cross sections for the reaction {gamma}{pi} {yields} {eta} Prime p that weremeasured by the CLAS-2009 and CBELSA/TAPS Collaborations (Mainz, Germany). It was shown that, in the photon energy region from the reaction threshold to 3700MeV, a good description of the experimental cross sections was attained by taking into account the contributions of high-angular-momenta heavy resonances alone.

  1. Investigation of photoneutron reactions close to and above the neutron emission threshold in the rare earth region

    SciTech Connect (OSTI)

    Hasper, J.; Mueller, S.; Savran, D.; Schnorrenberger, L.; Sonnabend, K.; Zilges, A.

    2008-01-15

    We have investigated the photoneutron cross section of the isotopes {sup 148,150}Nd, {sup 154}Sm, and {sup 154,160}Gd close to the neutron emission threshold in photoactivation experiments at the superconducting Darmstadt electron linear accelerator S-DALINAC. Naturally composed targets were activated with a high-intensity bremsstrahlung beam at various energies and the reaction yields have been determined by measuring the activity of the produced radioactive isotopes with HPGe detectors. The results are compared to two different statistical model calculations.

  2. Methods Research

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    Research Methods Research Methods being developed by MANTISSA Researchers Celeste: Bayesian modeling for astronomical images Randomized Linear Algebra for BioImaging Large-Scale PCA for Climate Efficient Graph Analytics for Genomics Unsupervised Learning for Neuroscience Deep Learning for Object Recognition Deep Learning for Daya Bay Unsupervised Learning in Neuroscience Last edited: 2016-07-18 16:52:3

  3. Evaluation of Shear Strength Threshold of Concern for Retrieval of Interim-Stored K-Basin Sludge in the Hanford Site

    SciTech Connect (OSTI)

    Onishi, Yasuo; Yokuda, Satoru T.; Schmidt, Andrew J.

    2010-11-01

    K-Basin sludge will be recovered into the Sludge Transport and Storage Containers (STSCs) and will be stored in the T Plant for interim storage (at least 10 years). Long-term sludge storage tests conducted by Pacific Northwest National Laboratory show that high uranium content K Basin sludge can self-cement and form a strong sludge with a bulk shear strength of up to 65 kPa. Some of this sludge has "paste" and "chunks" with shear strengths of approximately 3~5 kPa and 380 ~ 770 kPa, respectively. High uranium content sludge samples subjected to hydrothermal testing (e.g., 185°C, 10 h) have been observed to form agglomerates with a shear strength up to 170 kPa. After interim storage at T Plant, the sludge in the STSCs will be mobilized by water jets impinging the sludge. The objective of the evaluation was to determine the range of sludge shear strength for which there is high confidence that a water-jet retrieval system can mobilize stored K-Basin sludge from STSCs. The shear strength at which the sludge can be retrieved is defined as the "shear strength threshold of concern." If the sludge shear strength is greater than the value of the shear strength threshold of concern, a water-jet retrieval system will be unlikely to mobilize the sludge up to the container’s walls. The shear strength threshold of concern can be compared with the range of possible shear strengths of K-Basin stored sludge to determine if the current post interim-storage, water-jet retrieval method is adequate. Fourteen effective cleaning radius (ECR) models were reviewed, and their validity was examined by applying them to Hanford 241-SY-101 and 241-AZ-101 Tanks to reproduce the measured ECR produced by the mixer pumps. The validation test identified that the Powell-3 and Crowe-2 ECR models are more accurate than other ECR models reviewed. These ECR models were used to address a question as to whether the effective cleaning radius of a water jet is sufficient or if it can be readily expanded

  4. Investigation on the damage threshold of films coated on various silicate, fluorophosphate and phosphate laser glasses. Final report, January 1, 1979-August 29, 1980

    SciTech Connect (OSTI)

    Nakajima, Y; Izumitani, T

    1980-01-01

    Effects of substrate laser glass on the damage threshold and adhesion of dielectric films has been studied in order to improve the damage threshold. The study is divided into two parts: the first part dealing with four types of laser glass, LSG-91H silicate, LHG-8 phosphate, P-1 phosphate and LHG-10 fluorophosphate; the second part dealing with twenty-six glasses with systematically modified compositions in three glass systems, silicate, phosphate and fluorophosphate.

  5. Logarithmic compression methods for spectral data

    DOE Patents [OSTI]

    Dunham, Mark E.

    2003-01-01

    A method is provided for logarithmic compression, transmission, and expansion of spectral data. A log Gabor transformation is made of incoming time series data to output spectral phase and logarithmic magnitude values. The output phase and logarithmic magnitude values are compressed by selecting only magnitude values above a selected threshold and corresponding phase values to transmit compressed phase and logarithmic magnitude values. A reverse log Gabor transformation is then performed on the transmitted phase and logarithmic magnitude values to output transmitted time series data to a user.

  6. Ultralow-threshold laser and blue shift cooperative luminescence in a Yb{sup 3+} doped silica microsphere

    SciTech Connect (OSTI)

    Huang, Yantang Huang, Yu; Zhang, Peijin; Guo, Changlei; Department of Electronic Engineering, Institute of Optoelectronic Technology, Xiamen University, Xiamen, 361005

    2014-02-15

    An experimental investigation on ultralow threshold laser and blue shift cooperative luminescence (CL) in a Yb{sup 3+} doped silica microsphere (YDSM) with continuous-wave 976 nm laser diode pumping is reported. The experimental results show that the YDSM emits laser oscillation with ultralow threshold of 2.62 ?W, and the laser spectrum is modulated by the microsphere morphology characteristics. In addition, blue emission of YDSM is also observed with the increase of pump power, which is supposed to be generated by CL of excited Yb ion-pairs with the absorption of 976 nm photons and Si-O vibration phonons, and the process is explained with an energy level diagram. This property of the blue shift CL with phonons absorption in the Yb{sup 3+}doped microcavity makes it attractive for the application of laser cooling based on anti-Stokes fluorescence emission, if the Yb{sup 3+}doped microcavity made from with low phonon energy host materials.

  7. Precision Measurement of the p(e, e´p) π⁰ Reaction at Threshold

    SciTech Connect (OSTI)

    Chirapatpimol, K.; Shabestari, M.H.; Lindgren, R. A.; Smith, L. C.; Annand, J. R. M.; Higinbotham, D. W.; Moffit, B.

    2015-05-01

    New results are reported from a measurement of $\\pi^0$ electroproduction near threshold using the p(e, e´p) π⁰ reaction. The experiment was designed to determine precisely the energy dependence of $s-$ and $p-$wave electromagnetic multipoles as a stringent test of the predictions of Chiral Perturbation Theory (ChPT). The data were taken with an electron beam energy of 1192 MeV using a two-spectrometer setup in Hall A at Jefferson Lab. For the first time, complete coverage of the $\\phi^*_{\\pi}$ and $\\theta^*_{\\pi}$ angles in the $p \\pi^0$ center-of-mass was obtained for invariant energies above threshold from 0.5 MeV up to 15 MeV. The 4-momentum transfer $Q^2$ coverage ranges from 0.05 to 0.155 (GeV/c)$^2$ in fine steps. A simple phenomenological analysis of our data shows strong disagreement with $p-$wave predictions from ChPT for $Q^2>0.07$ (GeV/c)$^2$, while the $s-$wave predictions are in reasonable agreement.

  8. Precision Measurement of the p(e, e´p) π⁰ Reaction at Threshold

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Chirapatpimol, K.; Shabestari, M.H.; Lindgren, R. A.; Smith, L. C.; Annand, J. R. M.; Higinbotham, D. W.; Moffit, B.

    2015-05-01

    New results are reported from a measurement ofmore » $$\\pi^0$$ electroproduction near threshold using the p(e, e´p) π⁰ reaction. The experiment was designed to determine precisely the energy dependence of $s-$ and $p-$wave electromagnetic multipoles as a stringent test of the predictions of Chiral Perturbation Theory (ChPT). The data were taken with an electron beam energy of 1192 MeV using a two-spectrometer setup in Hall A at Jefferson Lab. For the first time, complete coverage of the $$\\phi^*_{\\pi}$$ and $$\\theta^*_{\\pi}$$ angles in the $$p \\pi^0$$ center-of-mass was obtained for invariant energies above threshold from 0.5 MeV up to 15 MeV. The 4-momentum transfer $Q^2$ coverage ranges from 0.05 to 0.155 (GeV/c)$^2$ in fine steps. A simple phenomenological analysis of our data shows strong disagreement with $p-$wave predictions from ChPT for $Q^2>0.07$ (GeV/c)$^2$, while the $s-$wave predictions are in reasonable agreement.« less

  9. Production of K⁺K⁻ pairs in proton-proton collisions below the Φ meson threshold

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Ye, Q. J.; Hartmann, M.; Chiladze, D.; Dymov, S.; Dzyuba, A.; Gao, H.; Gebel, R.; Hejny, V.; Kacharava, A.; Lorentz, B.; et al

    2013-06-12

    The pp→ppK⁺K⁻ reaction was measured below the Φ threshold at a beam energy of 2.568 GeV using the COSY-ANKE magnetic spectrometer. By assuming that the four-body phase space is distorted only by the product of two-body final-state interactions, fits to a variety of one-dimensional distributions permit the evaluation of differential and total cross sections. The shapes of the distributions in the Kp and Kpp invariant masses are reproduced only if the K⁻p interaction is even stronger than that found at higher energy. The cusp effect in the K⁺K⁻ distribution at the K⁰K¯¯¯⁰ threshold is much more clear and some evidencemore » is also found for coupling between the K⁻p and K¯¯¯⁰n channels. However, the energy dependence of the total cross section cannot be reproduced by considering only a simple product of such pairwise final-state interactions.« less

  10. Electrodeionization method

    DOE Patents [OSTI]

    Lin, YuPo J.; Hestekin, Jamie; Arora, Michelle; St. Martin, Edward J.

    2004-09-28

    An electrodeionization method for continuously producing and or separating and/or concentrating ionizable organics present in dilute concentrations in an ionic solution while controlling the pH to within one to one-half pH unit method for continuously producing and or separating and/or concentrating ionizable organics present in dilute concentrations in an ionic solution while controlling the pH to within one to one-half pH unit.

  11. Theoretical detection threshold of the proton-acoustic range verification technique

    SciTech Connect (OSTI)

    Ahmad, Moiz; Yousefi, Siavash; Xing, Lei; Xiang, Liangzhong

    2015-10-15

    Purpose: Range verification in proton therapy using the proton-acoustic signal induced in the Bragg peak was investigated for typical clinical scenarios. The signal generation and detection processes were simulated in order to determine the signal-to-noise limits. Methods: An analytical model was used to calculate the dose distribution and local pressure rise (per proton) for beams of different energy (100 and 160 MeV) and spot widths (1, 5, and 10 mm) in a water phantom. In this method, the acoustic waves propagating from the Bragg peak were generated by the general 3D pressure wave equation implemented using a finite element method. Various beam pulse widths (0.1–10 μs) were simulated by convolving the acoustic waves with Gaussian kernels. A realistic PZT ultrasound transducer (5 cm diameter) was simulated with a Butterworth bandpass filter with consideration of random noise based on a model of thermal noise in the transducer. The signal-to-noise ratio on a per-proton basis was calculated, determining the minimum number of protons required to generate a detectable pulse. The maximum spatial resolution of the proton-acoustic imaging modality was also estimated from the signal spectrum. Results: The calculated noise in the transducer was 12–28 mPa, depending on the transducer central frequency (70–380 kHz). The minimum number of protons detectable by the technique was on the order of 3–30 × 10{sup 6} per pulse, with 30–800 mGy dose per pulse at the Bragg peak. Wider pulses produced signal with lower acoustic frequencies, with 10 μs pulses producing signals with frequency less than 100 kHz. Conclusions: The proton-acoustic process was simulated using a realistic model and the minimal detection limit was established for proton-acoustic range validation. These limits correspond to a best case scenario with a single large detector with no losses and detector thermal noise as the sensitivity limiting factor. Our study indicated practical proton

  12. Method to improve reliability of a fuel cell system using low performance cell detection at low power operation

    SciTech Connect (OSTI)

    Choi, Tayoung; Ganapathy, Sriram; Jung, Jaehak; Savage, David R.; Lakshmanan, Balasubramanian; Vecasey, Pamela M.

    2013-04-16

    A system and method for detecting a low performing cell in a fuel cell stack using measured cell voltages. The method includes determining that the fuel cell stack is running, the stack coolant temperature is above a certain temperature and the stack current density is within a relatively low power range. The method further includes calculating the average cell voltage, and determining whether the difference between the average cell voltage and the minimum cell voltage is greater than a predetermined threshold. If the difference between the average cell voltage and the minimum cell voltage is greater than the predetermined threshold and the minimum cell voltage is less than another predetermined threshold, then the method increments a low performing cell timer. A ratio of the low performing cell timer and a system run timer is calculated to identify a low performing cell.

  13. Characterization methods

    SciTech Connect (OSTI)

    Glass, J.T.

    1993-01-01

    Methods discussed in this compilation of notes and diagrams are Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, and other surface analysis techniques (auger electron spectroscopy, x-ray photoelectron spectroscopy, electron energy loss spectroscopy, and scanning tunnelling microscopy). A comparative evaluation of different techniques is performed. In-vacuo and in-situ analyses are described.

  14. Estimating Methods

    Broader source: Directives, Delegations, and Requirements [Office of Management (MA)]

    1997-03-28

    Based on the project's scope, the purpose of the estimate, and the availability of estimating resources, the estimator can choose one or a combination of techniques when estimating an activity or project. Estimating methods, estimating indirect and direct costs, and other estimating considerations are discussed in this chapter.

  15. Coupling quantum dots to optical fiber: Low pump threshold laser in the red with a near top hat beam profile

    SciTech Connect (OSTI)

    Cheng, H.; Mironov, A. E.; Ni, J. H.; Yang, H. J.; Chen, W. W.; Dai, Z.; Park, S.-J.; Eden, J. G.; Dragic, P. D.; Dong, J.

    2015-02-23

    Direct coupling of the optical field in a ?244?nm thick, CdSe/ZnS quantum dot film to an optical fiber has yielded lasing in the red (? ? 644?nm) with a threshold pump energy density?

  16. Threshold Photoelectron Photoion Coincidence (TPEPICO) Studies: The Road to ? 0.1 kJ/mol Thermochemistry

    SciTech Connect (OSTI)

    Baer, Tomas

    2013-10-14

    The threshold photoelectron photoion coincidence (TPEPICO) technique is utilized to investigate the dissociation dynamics and thermochemistry of energy selected medium to large organic molecular ions. The reactions include parallel and consecutive steps that are modeled with the statistical theory in order to extract dissociation onsets for multiple dissociation paths. These studies are carried out with the aid of molecular orbital calculations of both ions and the transition states connecting the ion structure to their products. The results of these investigations yield accurate heats of formation of ions, free radicals, and stable molecules. In addition, they provide information about the potential energy surface that governs the dissociation process. Isomerization reactions prior to dissociation are readily inferred from the TPEPICO data.

  17. Threshold of photoelectron emission from CN{sub x} films deposited at room temperature and at 500 deg. C

    SciTech Connect (OSTI)

    Sago, Genki; Li Wanyan; Goto, Keisuke; Ichikawa, Yo; Ishida, Yoshihisa; Kohiki, Shigemi

    2004-10-15

    The threshold of photoelectron emission was measured for amorphous CN{sub x} films deposited at room temperature (RT) and at 500 deg. C. The x values of the films deposited at RT and at 500 deg. C by magnetron sputtering of a graphite target in a mixed N{sub 2}/Ar gas were 0.6 and 0.3, respectively. Ratios of the sp{sup 2}- to sp{sup 3}-hybridized components of both C and N for the film deposited at 500 deg. C were larger by {approx_equal}4 times than those for the film deposited at RT. The onsets of the electron emission by photon irradiation were 5.0 and 4.7 eV for the films deposited at RT and at 500 deg. C, respectively.

  18. Acute phytotoxicity of seven metals alone and in mixture: Are Italian soil threshold concentrations suitable for plant protection?

    SciTech Connect (OSTI)

    Baderna, Diego Lomazzi, Eleonora; Pogliaghi, Alberto; Ciaccia, Gianluca; Lodi, Marco; Benfenati, Emilio

    2015-07-15

    Metals can pollute soils in both urban and rural areas with severe impacts on the health of humans, plants and animals living there. Information on metal toxicity is therefore important for ecotoxicology. This study investigated the phytotoxicity of different metals frequently found as pollutants in soils: arsenic, cadmium, chromium, lead, mercury, nickel and zinc. Cucumber (Cucumis sativus), sorghum (Sorghum saccharatum) and cress (Lepidium sativum) seeds were used as models for other plants used in human nutrition such as cereals, rice, fruits and vegetables. The 72-h germination rate and root elongations were selected as short-term ecotoxicological endpoints in seeds exposed to single metals and mixtures. Metals were spiked onto OECD standard soils in concentrations comparable to current Italian contamination threshold concentrations for residential and commercial soils. Arsenic, chromium, mercury and nickel were the most toxic metals in our experimental conditions, particularly to cress seeds (5.172, 152 and 255.4 mg/kg as 72 h IC50 for arsenic, mercury and nickel respectively). Italian limits were acceptable for plant protection only for exposure to each metal alone but not for the mixtures containing all the metals concentrations expected by their respective legislative threshold. The effects of the mixture were class-specific: trends were comparable in dicots but different in monocots. The response induced by the mixture at high concentrations differed from that theoretically obtainable by summing the effects of the individual metals. This might be due to partial antagonism of the metals in soil or to the formation of complexes between the metals, which reduce the bioavailability of the pollutants for plants. - Graphical abstract: Metals investigated: Arsenic, Cadmium, Chromium, Lead, Mercury, Nickel and Zinc. - Highlights: • The short-term phytotoxicity of seven metals was investigated with 3 higher plants. • Italian limits for arsenic and nickel in

  19. COATING METHOD

    DOE Patents [OSTI]

    Townsend, R.G.

    1959-08-25

    A method is described for protectively coating beryllium metal by etching the metal in an acid bath, immersing the etched beryllium in a solution of sodium zincate for a brief period of time, immersing the beryllium in concentrated nitric acid, immersing the beryhlium in a second solution of sodium zincate, electroplating a thin layer of copper over the beryllium, and finally electroplating a layer of chromium over the copper layer.

  20. Effects of minimum monitor unit threshold on spot scanning proton plan quality

    SciTech Connect (OSTI)

    Howard, Michelle Beltran, Chris; Mayo, Charles S.; Herman, Michael G.

    2014-09-15

    Purpose: To investigate the influence of the minimum monitor unit (MU) on the quality of clinical treatment plans for scanned proton therapy. Methods: Delivery system characteristics limit the minimum number of protons that can be delivered per spot, resulting in a min-MU limit. Plan quality can be impacted by the min-MU limit. Two sites were used to investigate the impact of min-MU on treatment plans: pediatric brain tumor at a depth of 5–10 cm; a head and neck tumor at a depth of 1–20 cm. Three-field, intensity modulated spot scanning proton plans were created for each site with the following parameter variations: min-MU limit range of 0.0000–0.0060; and spot spacing range of 2–8 mm. Comparisons were based on target homogeneity and normal tissue sparing. For the pediatric brain, two versions of the treatment planning system were also compared to judge the effects of the min-MU limit based on when it is accounted for in the optimization process (Eclipse v.10 and v.13, Varian Medical Systems, Palo Alto, CA). Results: The increase of the min-MU limit with a fixed spot spacing decreases plan quality both in homogeneous target coverage and in the avoidance of critical structures. Both head and neck and pediatric brain plans show a 20% increase in relative dose for the hot spot in the CTV and 10% increase in key critical structures when comparing min-MU limits of 0.0000 and 0.0060 with a fixed spot spacing of 4 mm. The DVHs of CTVs show min-MU limits of 0.0000 and 0.0010 produce similar plan quality and quality decreases as the min-MU limit increases beyond 0.0020. As spot spacing approaches 8 mm, degradation in plan quality is observed when no min-MU limit is imposed. Conclusions: Given a fixed spot spacing of ≤4 mm, plan quality decreases as min-MU increased beyond 0.0020. The effect of min-MU needs to be taken into consideration while planning proton therapy treatments.

  1. Infrared emitting device and method

    DOE Patents [OSTI]

    Kurtz, Steven R.; Biefeld, Robert M.; Dawson, L. Ralph; Howard, Arnold J.; Baucom, Kevin C.

    1997-01-01

    An infrared emitting device and method. The infrared emitting device comprises a III-V compound semiconductor substrate upon which are grown a quantum-well active region having a plurality of quantum-well layers formed of a ternary alloy comprising InAsSb sandwiched between barrier layers formed of a ternary alloy having a smaller lattice constant and a larger energy bandgap than the quantum-well layers. The quantum-well layers are preferably compressively strained to increase the threshold energy for Auger recombination; and a method is provided for determining the preferred thickness for the quantum-well layers. Embodiments of the present invention are described having at least one cladding layer to increase the optical and carrier confinement in the active region, and to provide for waveguiding of the light generated within the active region. Examples have been set forth showing embodiments of the present invention as surface- and edge-emitting light emitting diodes (LEDs), an optically-pumped semiconductor laser, and an electrically-injected semiconductor diode laser. The light emission from each of the infrared emitting devices of the present invention is in the midwave infrared region of the spectrum from about 2 to 6 microns.

  2. Gelcasting methods

    DOE Patents [OSTI]

    Walls, Claudia A.; Kirby, Glen H.; Janney, Mark A.; Omatete, Ogbemi O.; Nunn, Stephen D.; McMillan, April D.

    2000-01-01

    A method of gelcasting includes the steps of providing a solution of at least hydroxymethylacrylamide (HMAM) and water. At least one inorganic powder is added to the mixture. At least one initiator system is provided to polymerize the HMAM. The initiator polymerizes the HMAM and water, to form a firm hydrogel that contains the inorganic powder. One or more comonomers can be polymerized with the HMAM monomer, to alter the final properties of the gelcast material. Additionally, one or more additives can be included in the polymerization mixture, to alter the properties of the gelcast material.

  3. Method of quantitating dsDNA

    DOE Patents [OSTI]

    Stark, Peter C.; Kuske, Cheryl R.; Mullen, Kenneth I.

    2002-01-01

    A method for quantitating dsDNA in an aqueous sample solution containing an unknown amount of dsDNA. A first aqueous test solution containing a known amount of a fluorescent dye-dsDNA complex and at least one fluorescence-attenutating contaminant is prepared. The fluorescence intensity of the test solution is measured. The first test solution is diluted by a known amount to provide a second test solution having a known concentration of dsDNA. The fluorescence intensity of the second test solution is measured. Additional diluted test solutions are similarly prepared until a sufficiently dilute test solution having a known amount of dsDNA is prepared that has a fluorescence intensity that is not attenuated upon further dilution. The value of the maximum absorbance of this solution between 200-900 nanometers (nm), referred to herein as the threshold absorbance, is measured. A sample solution having an unknown amount of dsDNA and an absorbance identical to that of the sufficiently dilute test solution at the same chosen wavelength is prepared. Dye is then added to the sample solution to form the fluorescent dye-dsDNA-complex, after which the fluorescence intensity of the sample solution is measured and the quantity of dsDNA in the sample solution is determined. Once the threshold absorbance of a sample solution obtained from a particular environment has been determined, any similarly prepared sample solution taken from a similar environment and having the same value for the threshold absorbance can be quantified for dsDNA by adding a large excess of dye to the sample solution and measuring its fluorescence intensity.

  4. Method and system for controlling a synchronous machine over full operating range

    DOE Patents [OSTI]

    Walters, James E.; Gunawan, Fani S.; Xue, Yanhong

    2002-01-01

    System and method for controlling a synchronous machine are provided. The method allows for calculating a stator voltage index. The method further allows for relating the magnitude of the stator voltage index against a threshold voltage value. An offset signal is generated based on the results of the relating step. A respective state of operation of the machine is determined. The offset signal is processed based on the respective state of the machine.

  5. Solitary pulse-on-demand production by optical injection locking of passively Q-switched InGaN diode laser near lasing threshold

    SciTech Connect (OSTI)

    Zeng, X. E-mail: dmitri.boiko@csem.ch; Stadelmann, T.; Grossmann, S.; Hoogerwerf, A. C.; Boko, D. L. E-mail: dmitri.boiko@csem.ch; Sulmoni, L.; Lamy, J.-M.; Grandjean, N.

    2015-02-16

    In this letter, we investigate the behavior of a Q-switched InGaN multi-section laser diode (MSLD) under optical injection from a continuous wave external cavity diode laser. We obtain solitary optical pulse generation when the slave MSLD is driven near free running threshold, and the peak output power is significantly enhanced with respect to free running configuration. When the slave laser is driven well above threshold, optical injection reduces the peak power. Using standard semiconductor laser rate equation model, we find that both power enhancement and suppression effects are the result of partial bleaching of the saturable absorber by externally injected photons.

  6. Calculation of resonances in a dt{mu} molecule by the R-matrix method

    SciTech Connect (OSTI)

    Mil'nikov, Gennady V.; Nakamura, Hiroki

    2003-03-01

    Using the spectral representation of Green's function, we calculate the density of states and extract parameters of resonances in the scattering system. The method is implemented for the resonances in the dt{mu} molecule below the t{mu} (n=2) threshold.

  7. System and method for quench and over-current protection of superconductor

    DOE Patents [OSTI]

    Huang, Xianrui; Laskaris, Evangelos Trifon; Sivasubramaniam, Kiruba Haran; Bray, James William; Ryan, David Thomas; Fogarty, James Michael; Steinbach, Albert Eugene

    2005-05-31

    A system and method for protecting a superconductor. The system may comprise a current sensor operable to detect a current flowing through the superconductor. The system may comprise a coolant temperature sensor operable to detect the temperature of a cryogenic coolant used to cool the superconductor to a superconductive state. The control circuit is operable to estimate the superconductor temperature based on the current flow and the coolant temperature. The system may also be operable to compare the estimated superconductor temperature to at least one threshold temperature and to initiate a corrective action when the superconductor temperature exceeds the at least one threshold temperature.

  8. Method and system for managing an electrical output of a turbogenerator

    DOE Patents [OSTI]

    Stahlhut, Ronnie Dean; Vuk, Carl Thomas

    2010-08-24

    The system and method manages an electrical output of a turbogenerator in accordance with multiple modes. In a first mode, a direct current (DC) bus receives power from a turbogenerator output via a rectifier where turbogenerator revolutions per unit time (e.g., revolutions per minute (RPM)) or an electrical output level of a turbogenerator output meet or exceed a minimum threshold. In a second mode, if the turbogenerator revolutions per unit time or electrical output level of a turbogenerator output are less than the minimum threshold, the electric drive motor or a generator mechanically powered by the engine provides electrical energy to the direct current bus.

  9. Method and system for managing an electrical output of a turbogenerator

    DOE Patents [OSTI]

    Stahlhut, Ronnie Dean; Vuk, Carl Thomas

    2009-06-02

    The system and method manages an electrical output of a turbogenerator in accordance with multiple modes. In a first mode, a direct current (DC) bus receives power from a turbogenerator output via a rectifier where turbogenerator revolutions per unit time (e.g., revolutions per minute (RPM)) or an electrical output level of a turbogenerator output meet or exceed a minimum threshold. In a second mode, if the turbogenerator revolutions per unit time or electrical output level of a turbogenerator output are less than the minimum threshold, the electric drive motor or a generator mechanically powered by the engine provides electrical energy to the direct current bus.

  10. Casting methods

    DOE Patents [OSTI]

    Marsden, Kenneth C.; Meyer, Mitchell K.; Grover, Blair K.; Fielding, Randall S.; Wolfensberger, Billy W.

    2012-12-18

    A casting device includes a covered crucible having a top opening and a bottom orifice, a lid covering the top opening, a stopper rod sealing the bottom orifice, and a reusable mold having at least one chamber, a top end of the chamber being open to and positioned below the bottom orifice and a vacuum tap into the chamber being below the top end of the chamber. A casting method includes charging a crucible with a solid material and covering the crucible, heating the crucible, melting the material, evacuating a chamber of a mold to less than 1 atm absolute through a vacuum tap into the chamber, draining the melted material into the evacuated chamber, solidifying the material in the chamber, and removing the solidified material from the chamber without damaging the chamber.

  11. WELDING METHOD

    DOE Patents [OSTI]

    Cornell, A.A.; Dunbar, J.V.; Ruffner, J.H.

    1959-09-29

    A semi-automatic method is described for the weld joining of pipes and fittings which utilizes the inert gasshielded consumable electrode electric arc welding technique, comprising laying down the root pass at a first peripheral velocity and thereafter laying down the filler passes over the root pass necessary to complete the weld by revolving the pipes and fittings at a second peripheral velocity different from the first peripheral velocity, maintaining the welding head in a fixed position as to the specific direction of revolution, while the longitudinal axis of the welding head is disposed angularly in the direction of revolution at amounts between twenty minutas and about four degrees from the first position.

  12. Tensiometer methods

    DOE Patents [OSTI]

    Grover, Blair K.; Hubbell, Joel M.; Sisson, James B.; Casper, William L.

    2005-12-20

    A method for collecting data regarding a matric potential of a media includes providing a tensiometer having a stainless steel tensiometer casing, the stainless steel tensiometer casing comprising a tip portion which includes a wetted porous stainless steel membrane through which a matric potential of a media is sensed; driving the tensiometer into the media using an insertion tube comprising a plurality of probe casing which are selectively coupled to form the insertion tube as the tensiometer is progressively driven deeper into the media, wherein the wetted porous stainless steel membrane is in contact with the media; and sensing the matric potential the media exerts on the wetted porous stainless steel membrane by a pressure sensor in fluid hydraulic connection with the porous stainless steel membrane. A tensiometer includes a stainless steel casing.

  13. Embedding Method

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    and Application of the Projection-Based Embedding Method Taylor B arnes NERSC A nnual M ee4ng, F eb. 2 4, 2 015 Outline Applica'on: I nves'ga'on o f t he Oxida've D ecomposi'on o f Lithium---Ion Ba=ery Solvents Development o f t he A ccurate Projec'on---Based W FT---in---DFT Embedding M ethod WFT DFT Outline Applica'on: I nves'ga'on o f t he Oxida've D ecomposi'on o f Lithium---Ion Ba=ery Solvents Development o f t he A ccurate Projec'on---Based W FT---in---DFT Embedding M ethod WFT DFT The S

  14. Method and apparatus for monitoring a hydrocarbon-selective catalytic reduction device

    DOE Patents [OSTI]

    Schmieg, Steven J; Viola, Michael B; Cheng, Shi-Wai S; Mulawa, Patricia A; Hilden, David L; Sloane, Thompson M; Lee, Jong H

    2014-05-06

    A method for monitoring a hydrocarbon-selective catalytic reactor device of an exhaust aftertreatment system of an internal combustion engine operating lean of stoichiometry includes injecting a reductant into an exhaust gas feedstream upstream of the hydrocarbon-selective catalytic reactor device at a predetermined mass flowrate of the reductant, and determining a space velocity associated with a predetermined forward portion of the hydrocarbon-selective catalytic reactor device. When the space velocity exceeds a predetermined threshold space velocity, a temperature differential across the predetermined forward portion of the hydrocarbon-selective catalytic reactor device is determined, and a threshold temperature as a function of the space velocity and the mass flowrate of the reductant is determined. If the temperature differential across the predetermined forward portion of the hydrocarbon-selective catalytic reactor device is below the threshold temperature, operation of the engine is controlled to regenerate the hydrocarbon-selective catalytic reactor device.

  15. Method to reduce damage to backing plate

    DOE Patents [OSTI]

    Perry, Michael D.; Banks, Paul S.; Stuart, Brent C.

    2001-01-01

    The present invention is a method for penetrating a workpiece using an ultra-short pulse laser beam without causing damage to subsequent surfaces facing the laser. Several embodiments are shown which place holes in fuel injectors without damaging the back surface of the sack in which the fuel is ejected. In one embodiment, pulses from an ultra short pulse laser remove about 10 nm to 1000 nm of material per pulse. In one embodiment, a plasma source is attached to the fuel injector and initiated by common methods such as microwave energy. In another embodiment of the invention, the sack void is filled with a solid. In one other embodiment, a high viscosity liquid is placed within the sack. In general, high-viscosity liquids preferably used in this invention should have a high damage threshold and have a diffusing property.

  16. Laser Gain and Threshold Properties in Compressive-Strained and Lattice-Matched GaInNAs/GaAs Quantum Wells

    SciTech Connect (OSTI)

    Chow, W.W.; Jones, E.D.; Modine, N.A.; Allerman, A.A.; Kurtz, S.R.

    1999-08-04

    The optical gain spectra for compressive-strained and lattice-matched GaInNAs/GaAs quantum wells are computed using a microscopic laser theory. From these spectra, the peak gain and carrier radiative decay rate as functions of carrier density are determined. These dependences allow the study of lasing threshold current density for different GAInNAs/GaAs laser structures.

  17. THE DISPERSION RELATIONS AND INSTABILITY THRESHOLDS OF OBLIQUE PLASMA MODES IN THE PRESENCE OF AN ION BEAM

    SciTech Connect (OSTI)

    Verscharen, Daniel; Chandran, Benjamin D. G. E-mail: benjamin.chandran@unh.edu

    2013-02-10

    An ion beam can destabilize Alfven/ion-cyclotron waves and magnetosonic/whistler waves if the beam speed is sufficiently large. Numerical solutions of the hot-plasma dispersion relation have previously shown that the minimum beam speed required to excite such instabilities is significantly smaller for oblique modes with k Multiplication-Sign B {sub 0} {ne} 0 than for parallel-propagating modes with k Multiplication-Sign B {sub 0} = 0, where k is the wavevector and B {sub 0} is the background magnetic field. In this paper, we explain this difference within the framework of quasilinear theory, focusing on low-{beta} plasmas. We begin by deriving, in the cold-plasma approximation, the dispersion relation and polarization properties of both oblique and parallel-propagating waves in the presence of an ion beam. We then show how the instability thresholds of the different wave branches can be deduced from the wave-particle resonance condition, the conservation of particle energy in the wave frame, the sign (positive or negative) of the wave energy, and the wave polarization. We also provide a graphical description of the different conditions under which Landau resonance and cyclotron resonance destabilize Alfven/ion-cyclotron waves in the presence of an ion beam. We draw upon our results to discuss the types of instabilities that may limit the differential flow of alpha particles in the solar wind.

  18. Tuning the conductivity threshold and carrier density of two-dimensional electron gas at oxide interfaces through interface engineering

    SciTech Connect (OSTI)

    Ma, H. J. Harsan E-mail: ariando@nus.edu.sg; Zeng, S. W.; Annadi, A.; Ariando E-mail: ariando@nus.edu.sg; Huang, Z.; Venkatesan, T.

    2015-08-15

    The two-dimensional electron gas (2DEG) formed at the perovskite oxides heterostructures is of great interest because of its potential applications in oxides electronics and nanoscale multifunctional devices. A canonical example is the 2DEG at the interface between a polar oxide LaAlO{sub 3} (LAO) and non-polar SrTiO{sub 3} (STO). Here, the LAO polar oxide can be regarded as the modulating or doping layer and is expected to define the electronic properties of 2DEG at the LAO/STO interface. However, to practically implement the 2DEG in electronics and device design, desired properties such as tunable 2D carrier density are necessary. Here, we report the tuning of conductivity threshold, carrier density and electronic properties of 2DEG in LAO/STO heterostructures by insertion of a La{sub 0.5}Sr{sub 0.5}TiO{sub 3} (LSTO) layer of varying thicknesses, and thus modulating the amount of polarization of the oxide over layers. Our experimental result shows an enhancement of carrier density up to a value of about five times higher than that observed at the LAO/STO interface. A complete thickness dependent metal-insulator phase diagram is obtained by varying the thickness of LAO and LSTO providing an estimate for the critical thickness needed for the metallic phase. The observations are discussed in terms of electronic reconstruction induced by polar oxides.

  19. Correction of the near threshold behavior of electron collisional excitation cross-sections in the plane-wave Born approximation

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Kilcrease, D. P.; Brookes, S.

    2013-08-19

    The modeling of NLTE plasmas requires the solution of population rate equations to determine the populations of the various atomic levels relevant to a particular problem. The equations require many cross sections for excitation, de-excitation, ionization and recombination. Additionally, a simple and computational fast way to calculate electron collisional excitation cross-sections for ions is by using the plane-wave Born approximation. This is essentially a high-energy approximation and the cross section suffers from the unphysical problem of going to zero near threshold. Various remedies for this problem have been employed with varying degrees of success. We present a correction procedure formore » the Born cross-sections that employs the Elwert–Sommerfeld factor to correct for the use of plane waves instead of Coulomb waves in an attempt to produce a cross-section similar to that from using the more time consuming Coulomb Born approximation. We compare this new approximation with other, often employed correction procedures. Furthermore, we also look at some further modifications to our Born Elwert procedure and its combination with Y.K. Kim's correction of the Coulomb Born approximation for singly charged ions that more accurately approximate convergent close coupling calculations.« less

  20. A semi-analytic power balance model for low (L) to high (H) mode transition power threshold

    SciTech Connect (OSTI)

    Singh, R., E-mail: rsingh129@yahoo.co.in [WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Institute for Plasma Research, Bhat Gandhinagar 2382 428 (India); Jhang, Hogun [WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Kaw, P. K. [Institute for Plasma Research, Bhat Gandhinagar 2382 428 (India); Diamond, P. H. [WCI Center for Fusion Theory, National Fusion Research Institute, Daejeon 305-333 (Korea, Republic of); Center for Momentum Transport and Flow Organization, University of California, San Diego, California 92093 (United States); Center for Astrophysics and Space Sciences, University of California, San Diego, 9500 Gilman Dr., La Jolla, California 92093-0424 (United States); Nordman, H. [Department of Earth and Space Sciences, Chalmers University of Technology, SE-412 96 Gteborg (Sweden); Bourdelle, C. [Euratom-CEA Association, CEA/DSM/DRFC, CEA Cadarache F-13108 Saint-Paul-Lez-Durance (France); Loarte, A. [ITER Organization, Route de Vinon Sur Verdon, A. 13115 Saint Paul Lez Durance (France)

    2014-06-15

    We present a semi-analytic model for low (L) to high (H) mode transition power threshold (P{sub th}). Two main assumptions are made in our study. First, high poloidal mode number drift resistive ballooning modes (high-m DRBM) are assumed to be the dominant turbulence driver in a narrow edge region near to last closed flux surface. Second, the pre-transition edge profile and turbulent diffusivity at the narrow edge region pertain to turbulent equipartition. An edge power balance relation is derived by calculating the dissipated power flux through both turbulent conduction and convection, and radiation in the edge region. P{sub th} is obtained by imposing the turbulence quench rule due to sheared E??B rotation. Evaluation of P{sub th} shows a good agreement with experimental results in existing machines. Increase of P{sub th} at low density (i.e., the existence of roll-over density in P{sub th} vs. density) is shown to originate from the longer scale length of the density profile than that of the temperature profile.

  1. Thickness effect on laser-induced-damage threshold of indium-tin oxide films at 1064 nm

    SciTech Connect (OSTI)

    Wang Haifeng; Huang Zhimeng; Zhang Dayong; Luo Fei; Huang Lixian; Li Yanglong; Luo Yongquan; Wang Weiping; Zhao Xiangjie

    2011-12-01

    Laser-induced-damage characteristics of commercial indium-tin oxide (ITO) films deposited by DC magnetron sputtering deposition on K9 glass substrates as a function of the film thickness have been studied at 1064 nm with a 10 ns laser pulse in the 1-on-1 mode, and the various mechanisms for thickness effect on laser-induced-damage threshold (LIDT) of the film have been discussed in detail. It is observed that laser-damage-resistance of ITO film shows dramatic thickness effect with the LIDT of the 50-nm ITO film 7.6 times as large as the value of 300 nm film, and the effect of depressed carrier density by decreasing the film thickness is demonstrated to be the primary reason. Our experiment findings indicate that searching transparent conductive oxide (TCO) film with low carrier density and high carrier mobility is an efficient technique to improve the laser-damage-resistance of TCO films based on maintaining their well electric conductivity.

  2. Method and apparatus for biological sequence comparison

    DOE Patents [OSTI]

    Marr, Thomas G.; Chang, William I-Wei

    1997-01-01

    A method and apparatus for comparing biological sequences from a known source of sequences, with a subject (query) sequence. The apparatus takes as input a set of target similarity levels (such as evolutionary distances in units of PAM), and finds all fragments of known sequences that are similar to the subject sequence at each target similarity level, and are long enough to be statistically significant. The invention device filters out fragments from the known sequences that are too short, or have a lower average similarity to the subject sequence than is required by each target similarity level. The subject sequence is then compared only to the remaining known sequences to find the best matches. The filtering member divides the subject sequence into overlapping blocks, each block being sufficiently large to contain a minimum-length alignment from a known sequence. For each block, the filter member compares the block with every possible short fragment in the known sequences and determines a best match for each comparison. The determined set of short fragment best matches for the block provide an upper threshold on alignment values. Regions of a certain length from the known sequences that have a mean alignment value upper threshold greater than a target unit score are concatenated to form a union. The current block is compared to the union and provides an indication of best local alignment with the subject sequence.

  3. Method and apparatus for biological sequence comparison

    DOE Patents [OSTI]

    Marr, T.G.; Chang, W.I.

    1997-12-23

    A method and apparatus are disclosed for comparing biological sequences from a known source of sequences, with a subject (query) sequence. The apparatus takes as input a set of target similarity levels (such as evolutionary distances in units of PAM), and finds all fragments of known sequences that are similar to the subject sequence at each target similarity level, and are long enough to be statistically significant. The invention device filters out fragments from the known sequences that are too short, or have a lower average similarity to the subject sequence than is required by each target similarity level. The subject sequence is then compared only to the remaining known sequences to find the best matches. The filtering member divides the subject sequence into overlapping blocks, each block being sufficiently large to contain a minimum-length alignment from a known sequence. For each block, the filter member compares the block with every possible short fragment in the known sequences and determines a best match for each comparison. The determined set of short fragment best matches for the block provide an upper threshold on alignment values. Regions of a certain length from the known sequences that have a mean alignment value upper threshold greater than a target unit score are concatenated to form a union. The current block is compared to the union and provides an indication of best local alignment with the subject sequence. 5 figs.

  4. Method for measuring multiple scattering corrections between liquid scintillators

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Verbeke, J. M.; Glenn, A. M.; Keefer, G. J.; Wurtz, R. E.

    2016-04-11

    In this study, a time-of-flight method is proposed to experimentally quantify the fractions of neutrons scattering between scintillators. An array of scintillators is characterized in terms of crosstalk with this method by measuring a californium source, for different neutron energy thresholds. The spectral information recorded by the scintillators can be used to estimate the fractions of neutrons multiple scattering. With the help of a correction to Feynman's point model theory to account for multiple scattering, these fractions can in turn improve the mass reconstruction of fissile materials under investigation.

  5. Infrared emitting device and method

    DOE Patents [OSTI]

    Kurtz, S.R.; Biefeld, R.M.; Dawson, L.R.; Howard, A.J.; Baucom, K.C.

    1997-04-29

    The infrared emitting device comprises a III-V compound semiconductor substrate upon which are grown a quantum-well active region having a plurality of quantum-well layers formed of a ternary alloy comprising InAsSb sandwiched between barrier layers formed of a ternary alloy having a smaller lattice constant and a larger energy bandgap than the quantum-well layers. The quantum-well layers are preferably compressively strained to increase the threshold energy for Auger recombination; and a method is provided for determining the preferred thickness for the quantum-well layers. Embodiments of the present invention are described having at least one cladding layer to increase the optical and carrier confinement in the active region, and to provide for waveguiding of the light generated within the active region. Examples have been set forth showing embodiments of the present invention as surface- and edge-emitting light emitting diodes (LEDs), an optically-pumped semiconductor laser, and an electrically-injected semiconductor diode laser. The light emission from each of the infrared emitting devices of the present invention is in the midwave infrared region of the spectrum from about 2 to 6 microns. 8 figs.

  6. One-photon mass-analyzed threshold ionization (MATI) spectroscopy of pyridine: Determination of accurate ionization energy and cationic structure

    SciTech Connect (OSTI)

    Lee, Yu Ran; Kang, Do Won; Kim, Hong Lae E-mail: hlkim@kangwon.ac.kr; Kwon, Chan Ho E-mail: hlkim@kangwon.ac.kr

    2014-11-07

    Ionization energies and cationic structures of pyridine were intensively investigated utilizing one-photon mass-analyzed threshold ionization (MATI) spectroscopy with vacuum ultraviolet radiation generated by four-wave difference frequency mixing in Kr. The present one-photon high-resolution MATI spectrum of pyridine demonstrated a much finer and richer vibrational structure than that of the previously reported two-photon MATI spectrum. From the MATI spectrum and photoionization efficiency curve, the accurate ionization energy of the ionic ground state of pyridine was confidently determined to be 73 570 ± 6 cm{sup −1} (9.1215 ± 0.0007 eV). The observed spectrum was almost completely assigned by utilizing Franck-Condon factors and vibrational frequencies calculated through adjustments of the geometrical parameters of cationic pyridine at the B3LYP/cc-pVTZ level. A unique feature unveiled through rigorous analysis was the prominent progression of the 10 vibrational mode, which corresponds to in-plane ring bending, and the combination of other totally symmetric fundamentals with the ring bending overtones, which contribute to the geometrical change upon ionization. Notably, the remaining peaks originate from the upper electronic state ({sup 2}A{sub 2}), as predicted by high-resolution photoelectron spectroscopy studies and symmetry-adapted cluster configuration interaction calculations. Based on the quantitatively good agreement between the experimental and calculated results, it was concluded that upon ionization the pyridine cation in the ground electronic state should have a planar structure of C{sub 2v} symmetry through the C-N axis.

  7. Anomalous reduction of the switching voltage of Bi-doped Ge{sub 0.5}Se{sub 0.5} ovonic threshold switching devices

    SciTech Connect (OSTI)

    Seo, Juhee; Ahn, Hyung-Woo; Shin, Sang-yeol; Cheong, Byung-ki; Lee, Suyoun

    2014-04-14

    Switching devices based on Ovonic Threshold Switching (OTS) have been considered as a solution to overcoming limitations of Si-based electronic devices, but the reduction of switching voltage is a major challenge. Here, we investigated the effect of Bi-doping in Ge{sub 0.5}Se{sub 0.5} thin films on their thermal, optical, electrical properties, as well as on the characteristics of OTS devices. As Bi increased, it was found that both of the optical energy gap (E{sub g}{sup opt}) and the depth of trap states decreased resulting in a drastic reduction of the threshold voltage (V{sub th}) by over 50%. In addition, E{sub g}{sup opt} was found to be about three times of the conduction activation energy for each composition. These results are explained in terms of the Mott delocalization effect by doping Bi.

  8. On the possibility of reducing the instability threshold of a parametric decay of an extraordinary wave into two upper hybrid waves in an inhomogeneous plasma

    SciTech Connect (OSTI)

    Popov, A. Yu. Gusakov, E. Z.

    2015-01-15

    A parametric decay instability (PDI) of an extraordinary wave leading to excitation of two upper hybrid (UH) plasmons at frequencies close to half the pump wave frequency is analyzed. It is shown that the two-plasmon PDI power threshold can be significantly reduced under conditions of electron cyclotron resonance heating (ECRH) experiments in toroidal magnetic devices, where the plasma density profile is often nonmonotonic, which leads to the localization of UH waves.

  9. Microsoft Word - NRAP-TRS-III-00X-2016_No-Impact Threshold Values for Groundwater Reduced-Order Models.final.2016.docx

    Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)

    No-Impact Threshold Values for Groundwater Reduced-Order Models 28 January 2016 Office of Fossil Energy NRAP-TRS-III-002-2016 Disclaimer This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus,

  10. Optical domain analog to digital conversion methods and apparatus

    DOE Patents [OSTI]

    Vawter, Gregory A

    2014-05-13

    Methods and apparatus for optical analog to digital conversion are disclosed. An optical signal is converted by mapping the optical analog signal onto a wavelength modulated optical beam, passing the mapped beam through interferometers to generate analog bit representation signals, and converting the analog bit representation signals into an optical digital signal. A photodiode receives an optical analog signal, a wavelength modulated laser coupled to the photodiode maps the optical analog signal to a wavelength modulated optical beam, interferometers produce an analog bit representation signal from the mapped wavelength modulated optical beam, and sample and threshold circuits corresponding to the interferometers produce a digital bit signal from the analog bit representation signal.

  11. Methods and systems for detecting abnormal digital traffic

    DOE Patents [OSTI]

    Goranson, Craig A [Kennewick, WA; Burnette, John R [Kennewick, WA

    2011-03-22

    Aspects of the present invention encompass methods and systems for detecting abnormal digital traffic by assigning characterizations of network behaviors according to knowledge nodes and calculating a confidence value based on the characterizations from at least one knowledge node and on weighting factors associated with the knowledge nodes. The knowledge nodes include a characterization model based on prior network information. At least one of the knowledge nodes should not be based on fixed thresholds or signatures. The confidence value includes a quantification of the degree of confidence that the network behaviors constitute abnormal network traffic.

  12. Method and apparatus for welding precipitation hardenable materials

    DOE Patents [OSTI]

    Murray, Jr., Holt; Harris, Ian D.; Ratka, John O.; Spiegelberg, William D.

    1994-01-01

    A method for welding together members consisting of precipitation age hardened materials includes the steps of selecting a weld filler material that has substantially the same composition as the materials being joined, and an age hardening characteristic temperature age threshold below that of the aging kinetic temperature range of the materials being joined, whereby after welding the members together, the resulting weld and heat affected zone (HAZ) are heat treated at a temperature below that of the kinetic temperature range of the materials joined, for obtaining substantially the same mechanical characteristics for the weld and HAZ, as for the parent material of the members joined.

  13. Method and apparatus for welding precipitation hardenable materials

    DOE Patents [OSTI]

    Murray, H. Jr.; Harris, I.D.; Ratka, J.O.; Spiegelberg, W.D.

    1994-06-28

    A method for welding together members consisting of precipitation age hardened materials includes the steps of selecting a weld filler material that has substantially the same composition as the materials being joined, and an age hardening characteristic temperature age threshold below that of the aging kinetic temperature range of the materials being joined, whereby after welding the members together, the resulting weld and heat affected zone (HAZ) are heat treated at a temperature below that of the kinetic temperature range of the materials joined, for obtaining substantially the same mechanical characteristics for the weld and HAZ, as for the parent material of the members joined. 5 figures.

  14. Systems and methods for deactivating a matrix converter

    DOE Patents [OSTI]

    Ransom, Ray M.

    2013-04-02

    Systems and methods are provided for deactivating a matrix conversion module. An electrical system comprises an alternating current (AC) interface, a matrix conversion module coupled to the AC interface, an inductive element coupled between the AC interface and the matrix conversion module, and a control module. The control module is coupled to the matrix conversion module, and in response to a shutdown condition, the control module is configured to operate the matrix conversion module to deactivate the first conversion module when a magnitude of a current through the inductive element is less than a threshold value.

  15. Method and system for turbomachinery surge detection

    DOE Patents [OSTI]

    Faymon, David K.; Mays, Darrell C.; Xiong, Yufei

    2004-11-23

    A method and system for surge detection within a gas turbine engine, comprises: measuring the compressor discharge pressure (CDP) of the gas turbine over a period of time; determining a time derivative (CDP.sub.D ) of the measured (CDP) correcting the CDP.sub.D for altitude, (CDP.sub.DCOR); estimating a short-term average of CDP.sub.DCOR.sup.2 ; estimating a short-term average of CDP.sub.DCOR ; and determining a short-term variance of corrected CDP rate of change (CDP.sub.roc) based upon the short-term average of CDP.sub.DCOR and the short-term average of CDP.sub.DCOR.sup.2. The method and system then compares the short-term variance of corrected CDP rate of change with a pre-determined threshold (CDP.sub.proc) and signals an output when CDP.sub.roc >CDP.sub.proc. The method and system provides a signal of a surge within the gas turbine engine when CDP.sub.roc remains>CDP.sub.proc for pre-determined period of time.

  16. BeZnCdSe quantum-well ridge-waveguide laser diodes under low threshold room-temperature continuous-wave operation

    SciTech Connect (OSTI)

    Feng, Jijun; Akimoto, Ryoichi

    2015-10-19

    Low threshold current ridge-waveguide BeZnCdSe quantum-well laser diodes (LDs) have been developed by completely etching away the top p-type BeMgZnSe/ZnSe:N short-period superlattice cladding layer, which can suppress the leakage current that flows laterally outside of the electrode. The waveguide LDs are covered with a thick SiO{sub 2} layer and planarized with chemical-mechanical polishing and a reactive ion etching process. Room-temperature lasing under continuous-wave condition is achieved with the laser cavity formed by the cleaved waveguide facets coated with high-reflectivity dielectric films. For a 4 μm-wide green LD lasing around a wavelength of 535 nm, threshold current and voltage of 7.07 mA and 7.89 V are achieved for a cavity length of 300 μm, and the internal differential quantum efficiency, internal absorption loss, gain constant, and nominal transparency current density are estimated to be 27%, 4.09 cm{sup −1}, 29.92 (cm × μm)/kA and 6.35 kA/(cm{sup 2 }× μm), respectively. This compact device can realize a significantly improved performance with much lower threshold power consumption, which would benefit the potential application for ZnSe-based green LDs as light sources in full-color display and projector devices installed in consumer products such as pocket projectors.

  17. Temperature and epi thickness dependence of the heavy ion induced latchup threshold for a CMOS/epi 16K static RAM

    SciTech Connect (OSTI)

    Smith, L.S.; Nichols, D.K.; Coss, J.R.; Price, W.E.; Binder, D.

    1987-12-01

    Data have been obtained with krypton and xenon ions for the latchup threshold vs. temperature of four different versions of a Harris CMOS/epi 16K static RAM. These special versions of the HM6516 RAM have 12-micron, 9-micron, 7-micron and 5-micron epi thicknesses, as grown. The test data showed a marked improvement in latchup resistance with decreasing epi thickness and with decreasing temperature over the range of 25/sup 0/C (operating chip ambient) to 100/sup 0/C.s.

  18. Localization-delocalization transition of electrons at the percolation threshold of semiconductor GaAs1–xNx alloys: The appearance of a mobility edge

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Alberi, K.; Fluegel, B.; Beaton, D. A.; Ptak, A. J.; Mascarenhas, A.

    2012-07-09

    Electrons in semiconductor alloys have generally been described in terms of Bloch states that evolve from constructive interference of electron waves scattering from perfectly periodic potentials, despite the loss of structural periodicity that occurs on alloying. Using the semiconductor alloy GaAs₁₋xNx as a prototype, we demonstrate a localized to delocalized transition of the electronic states at a percolation threshold, the emergence of a mobility edge, and the onset of an abrupt perturbation to the host GaAs electronic structure, shedding light on the evolution of electronic structure in these abnormal alloys.

  19. Damage threshold and focusability of mid-infrared free-electron laser pulses gated by a plasma mirror with nanosecond switching pulses

    SciTech Connect (OSTI)

    Wang, Xiaolong; Nakajima, Takashi; Zen, Heishun; Kii, Toshiteru; Ohgaki, Hideaki

    2013-11-04

    The presence of a pulse train structure of an oscillator-type free-electron laser (FEL) results in the immediate damage of a solid target upon focusing. We demonstrate that the laser-induced damage threshold can be significantly improved by gating the mid-infrared FEL pulses with a plasma mirror. Although the switching pulses we employ have a nanosecond duration which does not guarantee the clean wavefront of the gated FEL pulses, the high focusability is experimentally confirmed through the observation of spectral broadening by a factor of 2.1 when we tightly focus the gated FEL pulses onto the Ge plate.

  20. DAKOTA reliability methods applied to RAVEN/RELAP-7.

    SciTech Connect (OSTI)

    Swiler, Laura Painton; Mandelli, Diego; Rabiti, Cristian; Alfonsi, Andrea

    2013-09-01

    This report summarizes the result of a NEAMS project focused on the use of reliability methods within the RAVEN and RELAP-7 software framework for assessing failure probabilities as part of probabilistic risk assessment for nuclear power plants. RAVEN is a software tool under development at the Idaho National Laboratory that acts as the control logic driver and post-processing tool for the newly developed Thermal-Hydraulic code RELAP-7. Dakota is a software tool developed at Sandia National Laboratories containing optimization, sensitivity analysis, and uncertainty quantification algorithms. Reliability methods are algorithms which transform the uncertainty problem to an optimization problem to solve for the failure probability, given uncertainty on problem inputs and a failure threshold on an output response. The goal of this work is to demonstrate the use of reliability methods in Dakota with RAVEN/RELAP-7. These capabilities are demonstrated on a demonstration of a Station Blackout analysis of a simplified Pressurized Water Reactor (PWR).

  1. Transport-driven scrape-off layer flows and the x-point dependence of the L-H power threshold in Alcator C-Mod

    SciTech Connect (OSTI)

    LaBombard, B.; Rice, J.E.; Hubbard, A.E.; Hughes, J.W.; Greenwald, M.; Granetz, R.S.; Irby, J.H.; Lin, Y.; Lipschultz, B.; Marmar, E.S.; Marr, K.; Mossessian, D.; Parker, R.; Rowan, W.; Smick, N.; Snipes, J.A.; Terry, J.L.; Wolfe, S.M.; Wukitch, S.J.

    2005-05-15

    Factor of {approx}2 higher power thresholds for low- to high-confinement mode transitions (L-H) with unfavorable x-point topologies in Alcator C-Mod [Phys. Plasmas 1, 1511 (1994)] are linked to flow boundary conditions imposed by the scrape-off layer (SOL). Ballooning-like transport drives flow along magnetic field lines from low- to high-field regions with toroidal direction dependent on upper/lower x-point balance; the toroidal rotation of the confined plasma responds, exhibiting a strong counter-current rotation when Bx{nabla}B points away from the x point. Increased auxiliary heating power (rf, no momentum input) leads to an L-H transition at approximately twice the edge electron pressure gradient when Bx{nabla}B points away. As gradients rise prior to the transition, toroidal rotation ramps toward the co-current direction; the H mode is seen when the counter-current rotation imposed by the SOL flow becomes compensated. Remarkably, L-H thresholds in lower-limited discharges are identical to lower x-point discharges; SOL flows are also found similar, suggesting a connection.

  2. Investigation of near-threshold eta-meson production in the reaction {pi}{sup -}p{yields} {eta}n

    SciTech Connect (OSTI)

    Bayadilov, D. E.; Beloglazov, Yu. A.; Gridnev, A. B.; Kozlenko, N. G.; Kruglov, S. P.; Kulbardis, A. A.; Lopatin, I. V.; Novinskiy, D. V.; Radkov, A. K.; Sumachev, V. V.; Filimonov, E. A.; Shvedchikov, A. V.

    2012-08-15

    Differential and total cross sections for eta-meson production in the reaction {pi}{sup -}p {yields} {eta}n were measured within the experimental program eta-meson physics implemented in the pion channel of the synchrocyclotron of the Petersburg Nuclear Physics Institute (PNPI, Gatchina). These measurements were performed at incident-pion momenta (700, 710, 720, and 730 MeV/c) in the vicinity of the threshold for the process under study by using the neutral-meson spectrometer designed and created at the Meson Physics Laboratory of PNPI. It is shown that, in the immediate vicinity of the threshold (685 MeV/c), the process of eta-meson production proceeds predominantly via S{sub 11}(1535)-resonance formation followed by the decay S{sub 11}(1535) {yields} {eta}n (the respective branching fraction is Br Almost-Equal-To 60%), but that, as the momentum of incident pions increases, the role of the D wave becomes ever more important. A detailed analysis of this effect indicates that it is due to the increasing contribution of the D{sub 13}(1520) resonance. Although the branching fraction of the decay of this resonance through the {eta}n channel is assumed to be very small (BR Almost-Equal-To 0.24%), the effect is enhanced owing to the interference between the D wave and the dominant resonance S{sub 11}(1535).

  3. Measuring single-shot, picosecond optical damage threshold in Ge, Si, and sapphire with a 5.1-μm laser

    DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)

    Agustsson, R.; Pogorelsky, I.; Arab, E.; Murokh, A.; O"Shea, B.; Ovodenko, A.; Rosenzweig, J.; Solovyov, V.; Tilton, R.

    2015-11-18

    Optical photonic structures driven by picosecond, GW-class lasers are emerging as promising novel sources of electron beams and high quality X-rays. Due to quadratic dependence on wavelength of the laser ponderomotive potential, the performance of such sources scales very favorably towards longer drive laser wavelengths. However, to take full advantage of photonic structures at mid-IR spectral region, it is important to determine optical breakdown limits of common optical materials. To this end, an experimental study was carried out at a wavelength of 5 µm, using a frequency-doubled CO2 laser source, with 5 ps pulse length. Single-shot optical breakdowns were detectedmore » and characterized at different laser intensities, and damage threshold values of 0.2, 0.3, and 7.0 J/cm2, were established for Ge, Si, and sapphire, respectively. As a result, the measured damage threshold values were stable and repeatable within individual data sets, and across varying experimental conditions.« less

  4. Measuring single-shot, picosecond optical damage threshold in Ge, Si, and sapphire with a 5.1-μm laser

    SciTech Connect (OSTI)

    Agustsson, R.; Pogorelsky, I.; Arab, E.; Murokh, A.; O"Shea, B.; Ovodenko, A.; Rosenzweig, J.; Solovyov, V.; Tilton, R.

    2015-11-18

    Optical photonic structures driven by picosecond, GW-class lasers are emerging as promising novel sources of electron beams and high quality X-rays. Due to quadratic dependence on wavelength of the laser ponderomotive potential, the performance of such sources scales very favorably towards longer drive laser wavelengths. However, to take full advantage of photonic structures at mid-IR spectral region, it is important to determine optical breakdown limits of common optical materials. To this end, an experimental study was carried out at a wavelength of 5 µm, using a frequency-doubled CO2 laser source, with 5 ps pulse length. Single-shot optical breakdowns were detected and characterized at different laser intensities, and damage threshold values of 0.2, 0.3, and 7.0 J/cm2, were established for Ge, Si, and sapphire, respectively. As a result, the measured damage threshold values were stable and repeatable within individual data sets, and across varying experimental conditions.

  5. Systems and methods for initializing a charging system

    SciTech Connect (OSTI)

    Ransom, Ray M.; Perisic, Milun; Kajouke, Lateef A.

    2014-09-09

    Systems and methods are provided for initiating a charging system. The method, for example, may include, but is not limited to, providing, by the charging system, an incrementally increasing voltage to a battery up to a first predetermined threshold while the energy conversion module has a zero-percent duty cycle, providing, by the charging system, an incrementally increasing voltage to the battery from an initial voltage level of the battery up to a peak voltage of a voltage source while the energy conversion module has a zero-percent duty cycle, and providing, by the charging system, an incrementally increasing voltage to the battery by incrementally increasing the duty cycle of the energy conversion module.

  6. Systems and methods for initializing a charging system

    SciTech Connect (OSTI)

    Ransom, Ray M; Perisic, Milun; Kajouke, Lateef A

    2014-06-24

    Systems and methods are provided for initiating a charging system. The method, for example, may include, but is not limited to, providing, by the charging system, an incrementally increasing voltage to a battery up to a first predetermined threshold while the energy conversion module has a zero-percent duty cycle, providing, by the charging system, an incrementally increasing voltage to the battery from an initial voltage level of the battery up to a peak voltage of a voltage source while the energy conversion module has a zero-percent duty cycle, and providing, by the charging system, an incrementally increasing voltage to the battery by incrementally increasing the duty cycle of the energy conversion module.

  7. Method for nonlinear optimization for gas tagging and other systems

    DOE Patents [OSTI]

    Chen, T.; Gross, K.C.; Wegerich, S.

    1998-01-06

    A method and system are disclosed for providing nuclear fuel rods with a configuration of isotopic gas tags. The method includes selecting a true location of a first gas tag node, selecting initial locations for the remaining n-1 nodes using target gas tag compositions, generating a set of random gene pools with L nodes, applying a Hopfield network for computing on energy, or cost, for each of the L gene pools and using selected constraints to establish minimum energy states to identify optimal gas tag nodes with each energy compared to a convergence threshold and then upon identifying the gas tag node continuing this procedure until establishing the next gas tag node until all remaining n nodes have been established. 6 figs.

  8. Method for nonlinear optimization for gas tagging and other systems

    DOE Patents [OSTI]

    Chen, Ting; Gross, Kenny C.; Wegerich, Stephan

    1998-01-01

    A method and system for providing nuclear fuel rods with a configuration of isotopic gas tags. The method includes selecting a true location of a first gas tag node, selecting initial locations for the remaining n-1 nodes using target gas tag compositions, generating a set of random gene pools with L nodes, applying a Hopfield network for computing on energy, or cost, for each of the L gene pools and using selected constraints to establish minimum energy states to identify optimal gas tag nodes with each energy compared to a convergence threshold and then upon identifying the gas tag node continuing this procedure until establishing the next gas tag node until all remaining n nodes have been established.

  9. Method and apparatus for clockless analog-to-digital conversion and peak detection

    DOE Patents [OSTI]

    DeGeronimo, Gianluigi

    2007-03-06

    An apparatus and method for analog-to-digital conversion and peak detection includes at least one stage, which includes a first switch, second switch, current source or capacitor, and discriminator. The discriminator changes state in response to a current or charge associated with the input signal exceeding a threshold, thereby indicating whether the current or charge associated with the input signal is greater than the threshold. The input signal includes a peak or a charge, and the converter includes a peak or charge detect mode in which a state of the switch is retained in response to a decrease in the current or charge associated with the input signal. The state of the switch represents at least a portion of a value of the peak or of the charge.

  10. Methods for improved forewarning of condition changes in monitoring physical processes

    DOE Patents [OSTI]

    Hively, Lee M.

    2013-04-09

    This invention teaches further improvements in methods for forewarning of critical events via phase-space dissimilarity analysis of data from biomedical equipment, mechanical devices, and other physical processes. One improvement involves objective determination of a forewarning threshold (U.sub.FW), together with a failure-onset threshold (U.sub.FAIL) corresponding to a normalized value of a composite measure (C) of dissimilarity; and providing a visual or audible indication to a human observer of failure forewarning and/or failure onset. Another improvement relates to symbolization of the data according the binary numbers representing the slope between adjacent data points. Another improvement relates to adding measures of dissimilarity based on state-to-state dynamical changes of the system. And still another improvement relates to using a Shannon entropy as the measure of condition change in lieu of a connected or unconnected phase space.