Physics Commons^™

New Limit On Time-Reversal Violation In Beta Decay, H. P. Mumm, T. E. Chupp, R. L. Cooper, K. P. Coulter, S. J. Freedman, B. K. Fujikawa, A. Garcia, Gordon L. Jones, J. S. Nico, A. K. Thompson, C. A. Trull, J. F. Wilderson, F. E. Wietfeldt

Articles

We report the results of an improved determination of the triple correlation DP . (p(e) x p(v)) that can be used to limit possible time-reversal invariance in the beta decay of polarized neutrons and constrain extensions to the standard model. Our result is D = [-0.96 +/- 1.89(stat) +/- 1.01(sys)] x 10(-4). The corresponding phase between g(A) and g(V) is phi(AV) = 180.013 degrees +/- 0.028 degrees (68% confidence level). This result represents the most sensitive measurement of D in nuclear beta decay.

Development Of Dose Conversion Coefficients For Radionuclides Produced In Spallation Neutron Sources, Phillip W. Patton

Transmutation Sciences Physics (TRP)

A research consortium comprised of representatives from several universities and national laboratories will be established as part of this project to generate internal and external dose conversion coefficients for radionuclides produced in spallation neutron sources. Information obtained from this multi-year study will be used to support the siting and licensing of future accelerator-driven nuclear initiatives within the U.S. Department of Energy complex, including the Spallation Neutron Source (SNS) and Accelerator Production of Tritium (APT) projects. Determination of these coefficients will also fill data gaps for several hundred radionuclides that exist in Federal Guidance Report (FGR) No. 11 and in Publications …

The Role Of Llnl's Fast Calibration Facility In Diagnosing Nif Fusion Plasmas, Joshua G. Thompson, Carey Scott, Greg V. Brown

STAR Program Research Presentations

The Fusion and Astrophysics (FAST) Calibration and Diagnostic Facility uses the original Electron Beam Ion Trap (EBIT-I) to profile x-ray filters that are used in the Dante Soft X-Ray Diagnostic at the National Ignition Facility (NIF). FAST has an advantage over any other facility not only for its high accuracy, but also for its proximity to NIF in the Lawrence Livermore National Laboratory (LLNL). This makes for highly accurate and near-instantaneous filter calibration turnover.

EBIT-I was first constructed to create, trap, and observe static highly charged ions (HCIs) and conduct experimental astrophysics (creating an x-ray spectroscopy catalogue of ions). To …

Laboratory Astrophysics: Using Ebit Measurements To Interpret High Resolution Spectra From Celestial Sources, Carey Scott, Joshua Thompson, N. Hell, Greg V. Brown

STAR Program Research Presentations

Astrophysicists use radiation to investigate the physics controlling a variety of celestial sources, including stellar atmospheres, black holes, and binary systems. By measuring the spectrum of the emitted radiation, astrophysicists can determine a source’s temperature and composition. Accurate atomic data are needed for reliably interpreting these spectra. Here we present an overview of how LLNL’s EBIT facility is used to put the atomic data on sound footing for use by the high energy astrophysics community.

Surrogate Measurement Of The 238Pu(N,F) Cross Section, J. J. Ressler, J. T. Burke, J. Escher, C. Angell, M. S. Basunia, C. W. Beausang, L. A. Bernstein, D. L. Bleuel, R. J. Casperson, B. L. Goldblum, J. Gostic, R. Hatarik, R. Henderson, R. O. Hughes, J. Munson, L. Phair, T. J. Ross, N. D. Scielzo, E. Swanberg, I. Thompson, M. Wiedeking

Physics Faculty Publications

The neutron-induced fission cross section of ²³⁸Pu was determined using the surrogate ratio method. The (n,f) cross section over an equivalent neutron energy range 5–20 MeV was deduced from inelastic α-induced fission reactions on ²³⁹Pu, with ²³⁵U(α,α′f) and ²³⁶U(α,α′f) used as references. These reference reactions reflect ²³⁴U(n,f) and ²³⁵U(n,f) yields, respectively. The deduced ²³⁸Pu(n,f) cross section agrees well with standard data libraries up to …

The Economics Of The Atomic Bomb: Cost And Utilization, Jonathan M. Davis Mr.

Senior Honors Theses

Few moments in human history can be compared to the culmination of events that brought the atomic bomb into creation. It is incredible to contemplate that while a nation was fighting a two front war that spanned from Europe into the Pacific, that the United States was able to utilize the time, energy, brains, materials, manpower, and capital to complete a project in four years. That under any other circumstances would have taken greater than half a century to complete.

First, this thesis will discuss breakthroughs in research that led scientists to believe that the atomic weapons could be built, …

Coherent Photoproduction Of Π+ From 3he, R. Nasseripour, Gerard P. Gilfoyle, Et. Al.

Physics Faculty Publications

We have measured the differential cross section for the γ³He→ π⁺t reaction. This reaction was studied using the Continuous Electron Beam Accelerator Facility (CEBAF) Large Acceptance Spectrometer (CLAS) at Jefferson Lab. Real photons produced with the Hall-B bremsstrahlung tagging system in the energy range from 0.50 to 1.55 GeV were incident on a cryogenic liquid ³He target. The differential cross sections for the γ³He→ π⁺t reaction were measured as a function of photon-beam energy and pion-scattering angle. Theoretical predictions to date cannot explain the large cross sections except at backward angles, …

Measurement Of Parity-Violating Gamma-Ray Asymmetry In The Capture Of Polarized Cold Neutrons On Protons, M. T. Gericke, R. Alacorn, S. Balascuta, L. Barron-Palos, C. Blessinger, J. D. Bowman, R. D. Carlini, W. Chen, T. E. Chupp, C. Crawford, S. Covrig, M. Dabaghyan, N. Fomin, S. J. Freedman, T. R. Gentile, R. C. Gillis, G. L. Greene, F. W. Hersman, T. Ino, Gordon L. Jones, B. Lauss, M. Leuschner, W. R. Lozowski, R. Mahurin, Y. Masuda, J. Mei, G. S. Mitchell, S. Muto, H. Nann, S. A. Page, S. I. Penttila, W. D. Ramsay, A. Salas-Bacci, S. Santra, M. Sharma, P.-N. Seo, E. I. Sharapov, T. B. Smith, W. M. Snow, W. S. Wilburn, V. Yuan

Articles

The NPDGamma collaboration reports results from the first phase of a measurement of the parity violating up-down asymmetry A(gamma) with respect to the neutron spin direction of gamma rays emitted in the reaction (n) over right arrow + p -> d + gamma using the capture of polarized cold neutrons on the protons in a liquid parahydrogen target. One expects parity-odd effects in the hadronic weak interaction between nucleons to be induced by the weak interaction between quarks. A(gamma) in (n) over right arrow + p -> d + gamma is dominated by a Delta I = 1, S-3(1)-P-3(1) parity-odd …

Analysis Of Electrodeposited Nickel-Iron Alloy Film Composition Using Particle-Induced X-Ray Emission, Alyssa Frey, Nicholas Wozniak, Timothy Nagi, Matthew Keller, J. Mark Lunderberg, Graham F. Peaslee, Paul Deyoung, Jennifer R. Hampton

Faculty Publications

The elemental composition of electrodeposited NiFe thin films was analyzed with particle-induced X-ray emission (PIXE). The thin films were electrodeposited on polycrystalline Au substrates from a 100mM NiSO₄, 10 mM FeSO₄, 0.5M H₃BO₃, and 1M Na₂SO₄ solution. PIXE spectra of these films were analyzed to obtain relative amounts of Ni and Fe as a function of deposition potential and deposition time. The results show that PIXE can measure the total deposited metal in a sample over at least four orders of magnitude with similar fractional uncertainties. The technique is …

Conceptual Design Of A Polarized Medium Energy Electron-Ion Collider At Jlab, S. Ahmed, A. Bogacz, Ya. Derbenev, A. Hutton, Geoffrey Krafft, R. Li, V. Morozov, F. Pilat, R. Rimmer, Y. Roblin, T. Satogata, M. Spata, B. Terzić, M. Tiefenback, H. Wang, B. Yunn, Y. Zhang, P. Chetsov, Jean R. Delayen, Subashini Desilva, Hisham Sayed, V. Dudnikov, R. Johnson, F. Marhauser, M. Sullivan, S. Manikonda, P. N. Ostroumov, S. Abeyratne, B. Erdelyi, Y. Kim, A. Kondratenko

Physics Faculty Publications

A medium energy electron-ion collider is envisioned as the primary future of the JLab nuclear science program beyond the 12 GeV upgraded CEBAF. The present conceptual design selects a ring-ring collider option, covers a CM energy range up to 65 GeV for collisions of polarized electrons with polarized light ions or unpolarized light to heavy ions, and reaches a luminosity at above 10³⁴ cm^-2s^-1 per detector over multiple interaction points. This paper presents a brief description of the current conceptual design of the accelerator.

Precise Measurements Of Beam Spin Asymmetries In Semi-Inclusive Π0 Production, M. Aghasyan, H. Avakian, P. Rossi, E. De Sanctis, D. Hasch, M. Mirazita, D. Adikaram, M. J. Amaryan, M. Anghinolfi, H. Baghdasaryan, R. P. Bennett, S. Bültmann, G. E. Dodge, C. E. Hyde, A. Klein, S. E. Kuhn, M. Mayer, H. Seraydaryan, L. B. Weinstein

Physics Faculty Publications

We present studies of single-spin asymmetries for neutral pion electroproduction in semi-inclusive deep-inelastic scattering of 5.776 GeV polarized electrons from an unpolarized hydrogen target, using the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. A substantial sin phi(h) amplitude has been measured in the distribution of the cross section asymmetry as a function of the azimuthal angle φh of the produced neutral pion. The dependence of this amplitude on Bjorken x and on the pion transverse momentum is extracted with significantly higher precision than previous data and is compared to model calculations. (C) 2011 Elsevier B.V.

Evolution Of The Differential Transverse Momentum Correlation Function With Centrality In Au + Au Collisions At √Snn = 200 Gev, G. Agakishiev, M. M. Aggarwal, Z. Ahammed, A. V. Alakhverdyants, I. Alekseev, J. Alford, B. D. Anderson, C. D. Anson, D. Arhipkin, G. S. Averichev, S. Bültmann, D. Plyku

Physics Faculty Publications

We present first measurements of the evolution of the differential transverse momentum correlation function, C, with collision centrality in Au + Au interactions at √^sNN = 200 GeV. This observable exhibits a strong dependence on collision centrality that is qualitatively similar to that of number correlations previously reported. We use the observed longitudinal broadening of the near-side peak of C with increasing centrality to estimate the ratio of the shear viscosity to entropy density, η / s , of the matter formed in central Au + Au interactions. We obtain an upper limit estimate of η / s …

Two-Body Photodisintegration Of 3he Between 7 And 16 Mev, W. Tornow, H. J. Karwowski, J. H. Kelley, R. Raut, G. Rusev, S. C. Stave, A. P. Tonchev, A. Deltuva, A. C. Fonseca, L. E. Marcucci, R. Schiavilla

Physics Faculty Publications

A comprehensive data set is reported for the two-body photodisintegration cross section of ³He using mono-energetic photon beams at eleven energies between 7.0 and 16.0 MeV. A ³He + Xe high-pressure gas scintillator served as target and detector. Although our data are in much better agreement with our state-of-the-art theoretical calculations than the majority of the previous data, these calculations underpredict the new data by about 10%. This disagreement suggests an incomplete understanding of the dynamics of the three-nucleon system and its response to electromagnetic probes.

Scaling Properties At Freeze-Out In Relativistic Heavy-Ion Collisions, M. M. Aggarwal, Z. Ahammed, A. V. Alakhverdyants, I. Alekseev, J. Alford, B. D. Anderson, S. Bueltmann, I. Koralt, D. Plyku, Star Collaboration

Physics Faculty Publications

Identified charged pion, kaon, and proton spectra are used to explore the system size dependence of bulk freeze-out properties in Cu+Cu collisions at √sNN=200 and 62.4 GeV. The data are studied with hydrodynamically motivated blast-wave and statistical model frameworks in order to characterize the freeze-out properties of the system. The dependence of freeze-out parameters on beam energy and collision centrality is discussed. Using the existing results from Au + Au and pp collisions, the dependence of freeze-out parameters on the system size is also explored. This multidimensional systematic study furthers our understanding of the QCD phase diagram revealing the importance …

Experimental Results In Dis, Sidis And Des From Jefferson Lab, Sebastian E. Kuhn

Physics Faculty Publications

Jefferson Lab’s electron accelerator in its present incarnation, with a maximum beam energy slightly above 6 GeV, has already enabled a large number of experiments expanding our knowledge of nucleon and nuclear structure (especially in Deep Inelastic Scattering—DIS—at moderately high x, and in the resonance region). Several pioneering experiments have yielded first results on Deeply Virtual Compton Scattering (DVCS) and other Deep Exclusive Processes (DES), and the exploration of the rich landscape of transverse momentum‐dependent (TMD) structure functions using Semi‐Inclusive electron scattering (SIDIS) has begun. With the upgrade of CEBAF to 12 GeV now underway, a significantly larger kinematic …

Anisotropic Response Of Nanosized Bismuth Films Upon Femtosecond Laser Excitation Monitored By Ultrafast Electron Diffraction, Ahmed R. Esmail, Hani E. Elsayed-Ali

Electrical & Computer Engineering Faculty Publications

The lattice response of 5 nm thick bismuth film to femtosecond laser excitation is probed by ultrafast electron diffraction. The transient decay time after laser excitation is greater for diffraction from (012) lattice planes compared to (110) planes and is reduced for both planes with the increased laser fluence. These results indicate that different energy coupling mechanisms to the lattice occur depending on the crystal direction. The behavior of the diffraction peak width indicates partial disorder of the film upon photoexcitation that increases together with the laser fluence. © 2011 American Institute of Physics. [doi:10.1063/1.3652919]