Search Menu
DOE PAGES title logo U.S. Department of Energy
Office of Scientific and Technical Information
Search Scholarly Publications

90 Search Results

Sorted by Relevance
Save Results
...

  1. Testing of a 15 kA Superconducting Transformer

    Kumar, Mithlesh ; Joshi, Piyush ; Gupta, Ramesh ; ... - IEEE Transactions on Applied Superconductivity
    Here, the manufacturing of superconducting magnets for High Energy Physics (HEP) and Fusion Energy Sciences (FES) applications requires high-current conductors to generate stronger magnetic fields without increasing the inductance of the magnet. Increased inductance is undesirable due to the associated AC losses, which reduce the temperature margin; and the quench protection also becomes complicated. Testing high-current conductors with a direct current (DC) room temperature power supply is unfeasible for two primary reasons: 1) the limited capacity to supply large currents, and 2) the significant heat load losses at the current leads. A superconducting transformer offers a solution to both challenges.more » A 50-kA superconducting transformer is planned for manufacturing and commissioning at Brookhaven National Laboratory as part of its user facility upgrade. This transformer will facilitate the testing of superconducting cables, conductors, joints, and insert coils under high magnetic field conditions (10 T) and with currents up to 50-kA. To evaluate the manufacturing process and validate the theoretical models, the magnet division has developed and tested a 15-kA prototype transformer. A control loop has been implemented to ensure precise current delivery to the sample. This paper presents the coil design, manufacturing, and experimental results from the cold tests.« less

  2. Partial wave analysis of 𝑒+β’π‘’βˆ’ β†’ πœ‹+β’πœ‹βˆ’β’π½/πœ“ and cross section measurement of 𝑒+β’π‘’βˆ’ β†’ πœ‹ Β± ⁒𝑍𝑐⁒(3900)βˆ“ from 4.1271 to 4.3583 GeV

    Ablikim, M. ; Achasov, M. N. ; Adlarson, P. ; ... - Physical Review. D.
    Based on 12.0 fbβˆ’1 of 𝑒+β’π‘’βˆ’ collision data samples collected by the BESIII detector at center-of-mass energies from 4.1271 to 4.3583 GeV, a partial wave analysis is performed for the process 𝑒+β’π‘’βˆ’ β†’ πœ‹+β’πœ‹βˆ’β’π½/πœ“. The cross sections for the subprocesses 𝑒+β’π‘’βˆ’ β†’ πœ‹+⁒𝑍𝑐⁒(3900)βˆ’ + c.c. β†’ πœ‹+β’πœ‹βˆ’β’π½/πœ“, 𝑓0⁑(980)⁒(β†’ πœ‹+β’πœ‹βˆ’)⁒𝐽/πœ“, and (πœ‹+β’πœ‹βˆ’)Sβˆ’wave⁒𝐽/πœ“ are measured for the first time. The mass and width of the 𝑍𝑐⁒(3900)Β± are determined to be 3884.6 Β± 0.7 Β± 3.3 MeV/𝑐2 and 37.2 Β± 1.3 Β± 6.6 MeV, respectively. The first errors are statistical and the second systematic. The final state (πœ‹+β’πœ‹βˆ’)Sβˆ’wave⁒𝐽/πœ“ dominates the process 𝑒+β’π‘’βˆ’ β†’more » πœ‹+β’πœ‹βˆ’β’π½/πœ“. By analyzing the cross sections of πœ‹Β±β’π‘π‘β’(3900)βˆ“ and 𝑓0⁑(980)⁒𝐽/πœ“, π‘Œβ‘(4220) has been observed. Its mass and width are determined to be 4225.7 Β± 4.1 Β± 3.4 MeV/𝑐2 and 57.5 Β± 9.4 Β± 12.1 MeV, respectively.« less

  3. Lepton flavor violation by three units

    Heeck, Julian ; Sokhashvili, Mikheil ; Thapa, Anil - Physical Review. D.
    The conservation of lepton flavor is a prediction of the Standard Model and is still an excellent approximate symmetry despite our observation of neutrino oscillations. Lepton flavor violation by one or two units has been discussed for decades, with several dedicated experiments exploring the vast model landscape but no discoveries so far. Here, we explore operators and processes that violate at least one lepton flavor by three units and identify testable signatures. In the Standard Model effective field theory, such operators already arise at mass dimension 7 and can be tested through their contributions to Michel parameters in leptonic decays.more » True neutrinoless charged-lepton flavor violation arises at mass dimension 10 and can realistically only be seen in the tau decay channels 𝜏 β†’ $$𝑒⁒𝑒⁒𝑒⁒\bar{πœ‡}⁒\bar{πœ‡}$$ or 𝜏 β†’ $$πœ‡β’πœ‡β’πœ‡\bar{𝑒}\bar{𝑒}$$, for example in Belle II. Testable rates for these tau decays require light new particles and subsequently predict an avalanche of remarkably clean but so-far unconstrained collider signatures.« less

  4. Measurement of the Higgs boson mass and width using the four-lepton final state in proton-proton collisions at $$\sqrt{s}$$ =13  TeV

    Hayrapetyan, A. ; Tumasyan, A. ; Adam, W. ; ... - Physical Review. D.
    A measurement of the Higgs boson mass and width via its decay to two 𝑍 bosons is presented. Proton-proton collision data collected by the CMS experiment, corresponding to an integrated luminosity of 138  fbβˆ’1 at a center-of-mass energy of 13 TeV, is used. The invariant mass distribution of four leptons in the on-shell Higgs boson decay is used to measure its mass and constrain its width. This yields the most precise single measurement of the Higgs boson mass to date, 125.04 Β± 0.12  GeV, and an upper limit on the width Γ𝐻 < 330 MeV at 95% confidence level. A combination ofmore » the on- and off-shell Higgs boson production decaying to four leptons is used to determine the Higgs boson width, assuming that no new virtual particles affect the production, a premise that is tested by adding new heavy particles in the gluon fusion loop model. This result is combined with a previous CMS analysis of the off-shell Higgs boson production with decay to two leptons and two neutrinos, giving a measured Higgs boson width of 3.0$$^{+2.0}_{βˆ’1.5}$$ MeV, in agreement with the standard model prediction of 4.1 MeV. The strength of the off-shell Higgs boson production is also reported. The scenario of no off-shell Higgs boson production is excluded at a confidence level corresponding to 3.8 standard deviations.« less

  5. Probing New Bosons and Nuclear Structure with Ytterbium Isotope Shifts

    Door, Menno ; Yeh, Chih-Han ; Heinz, Matthias ; ... - Physical Review Letters
    In this Letter, we present mass-ratio measurements on highly charged Yb42+ ions with a precision of 4 Γ—10-12 and isotope-shift measurements on Yb+ on the 2S1/2 β†’ 2D5/2 and 2S1/2 β†’ 2F7/2 transitions with a precision of 4 Γ—10-9 for the isotopes 168,170,172,174,176 Yb. We present a new method that allows us to extract higher-order changes in the nuclear charge distribution along the Yb isotope chain, benchmarking ab initio nuclear structure calculations. Additionally, we perform a King plot analysis to set bounds on a fifth force in the keV/c2 to MeV/c2 range coupling to electrons and neutrons.

  6. Observation of New Charmonium or Charmoniumlike States in B+ β†’ D*Β±Dβˆ“K+ Decays

    Aaij, R. ; Abdelmotteleb, A. S. W. ; Abellan Beteta, C. ; ... - Physical Review Letters
    A study of resonant structures in 𝐡+→𝐷*+β’π·βˆ’β’πΎ+ and 𝐡+→𝐷*βˆ’β’π·+⁒𝐾+ decays is performed, using proton-proton collision data at center-of-mass energies of βˆšπ‘  =7, 8, and 13 TeV recorded by the LHCb experiment, corresponding to an integrated luminosity of 9 fbβˆ’1. A simultaneous amplitude fit is performed to the two channels with contributions from resonances decaying to 𝐷*βˆ’β’π·+ and 𝐷*+β’π·βˆ’ states linked by 𝐢 parity. This procedure allows the 𝐢 parities of resonances in the 𝐷*Β±β’π·βˆ“ mass spectra to be determined. Four charmonium or charmoniumlike states are observed decaying into 𝐷*Β±β’π·βˆ“: πœ‚π‘β‘(3945), β„Žπ‘β‘(4000), πœ’π‘β’1⁑(4010), and β„Žπ‘β‘(4300), with quantum numbers 𝐽𝑃⁒𝐢 equal tomore » 0βˆ’+, 1+βˆ’, 1++, and 1+βˆ’, respectively. At least three of these states have not been observed previously. In addition, the existence of the 𝑇$$^*_{\bar{c}\bar{s}0}$$⁒(2870)0 and 𝑇$$^*_{\bar{c}\bar{s}1}$$(2900)0 resonances in the π·βˆ’β’πΎ+ mass spectrum, already observed in the 𝐡+→𝐷+β’π·βˆ’β’πΎ+ decay, is confirmed in a different production channel.« less

  7. Evolution of shell gaps in the neutron-poor calcium region from invariant-mass spectroscopy of 37,38Sc, 35Ca, 34K

    Dronchi, N. ; Charity, R. J. ; Sobotka, L. G. ; ... - Physical Review. C
    A fast secondary beam of 37Ca impinged on a 9Be target resulting in a set of reactions populating proton-rich nuclei including 35Ca and the first observations of 37,38Sc and 34K. Invariant-mass spectroscopy, used to reconstruct proton decays for these nuclei, yielded three new ground-state masses and information on their low-lying structures. The newly measured mass excesses are: Ξ”M(37Sc) = 3500(410) keV, Ξ”M(38Sc) = –4656(14) keV, and Ξ”M(34K) = –1487(17) keV. These nuclei straddle the well-known Z = 20 shell closure as well as the N = 16 subshell closure. Furthermore, trends in separation energies help elucidate how nuclear structure evolvesmore » showing a fading of the Z = 20 shell gap for N β‰₯ 18 and indications of a N = 16 subshell gap.« less

  8. Trace anomaly form factors from lattice QCD

    Wang, Bigeng ; He, Fangcheng ; Wang, Gen ; ... - Physical Review. D.
    The hadron mass can be obtained through the calculation of the trace of the energy-momentum tensor in the hadron which includes the trace anomaly and sigma terms. The anomaly due to conformal symmetry breaking is believed to be an important ingredient for hadron mass generation and confinement. In this work, we will present the calculation of the glue part of the trace anomaly form factors of the pion up to Q 2 ∼ 4.3     GeV 2 and the nucleon up to Q 2 ∼ 1     GeVmore » 2 . The calculations are performed on a domain wall fermion ensemble with overlap valence quarks at seven valence pion masses varying from ∼ 250 to ∼ 540     MeV , including the unitary point ∼ 340     MeV . We calculate the radius of the glue trace anomaly for the pion and the nucleon from the z expansion. By performing a two-dimensional Fourier transform on the glue trace anomaly form factors in the infinite momentum frame with no energy transfer, we also obtain their spatial distributions for several valence quark masses. The results are qualitatively extrapolated to the physical valence pion mass with systematic errors from the unphysical sea quark mass, discretization effects in the renormalization sum rule, and finite-volume effects to be addressed in the future. We find the pion’s form factor changes sign, as does its spatial distribution, for light quark masses. This explains how the trace anomaly contribution to the pion mass approaches zero toward the chiral limit. Published by the American Physical Society 2024« less

  9. Precision Mass Measurement of the Proton Dripline Halo Candidate 22Al

    Campbell, S. E. ; Bollen, G. ; Brown, B. A. ; ... - Physical Review Letters
    Here, we report the first mass measurement of the proton-halo candidate 22Al performed with the low energy beam ion trap facility’s 9.4 T Penning trap mass spectrometer at facility for rare isotope beams. This measurement completes the mass information for the lightest remaining proton-dripline nucleus achievable with Penning traps. 22Al has been the subject of recent interest regarding a possible halo structure from the observation of an exceptionally large isospin asymmetry [J. Lee et al., Large isospin asymmetry in Si22/O22 Mirror Gamow-Teller transitions reveals the halo structure of 22Al , Phys. Rev. Lett. 125, 192503 (2020).]. The measured mass excessmore » value of ME=18 092.5⁒(3) keV, corresponding to an exceptionally small proton separation energy of 𝑆𝑝=100.4⁒(8) keV, is compatible with the suggested halo structure. Our result agrees well with predictions from 𝑠⁒𝑑-shell USD Hamiltonians. While USD Hamiltonians predict deformation in the 22Al ground state with minimal 1⁒𝑠1/2 occupation in the proton shell, a particle-plus-rotor model in the continuum suggests that a proton halo could form at large quadrupole deformation. These results emphasize the need for a charge radius measurement to conclusively determine the halo nature.« less

  10. ORBUMP Pulsed Dipole Magnet Design for Fermilab Booster

    Kashikhin, Vladimir ; Harding, David ; Huang, Yuenian ; ... - IEEE Transactions on Applied Superconductivity
    Fermilab initiated the accelerator magnet system upgrade project PIP-II for future neutrino experiments. Old ORBUMP pulsed dipoles should be replaced with new stronger magnets occupying the same space as old ones. Four of these magnets connected in series form dogleg type of proton beam orbit. The magnet field and 19 kA current pulse length are close to 1 ms. Old magnet cores were based on a ferrite material. For new magnets, a magnet gap field is above 0.4 T, which completely saturates ferrite material. So, for the magnet core, 0.127 mm thick laminations of low carbon steel with inorganic coating,more » as the magnet were placed in a vacuum box. There were investigated transient magnet parameters including skin effect in the iron core and in the single-turn copper coil. The integrated field homogeneity was improved by the copper coil shimming. Simulated by OPERA3D power losses were used for the thermal analysis by ANSYS code. The magnet performance is strongly coupled with the power source. The dynamic magnet inductance and resistance were included in the pulsed power source design. Finally, the paper presented the ORBUMP magnet system design.« less
...
Search for:
All Records
Subject
accelerator mass spectrometry AMS
Refine by:
Article Type
Availability
Journal
more less
Creator / Author
more less
Publication Date
Research Organization
more less