Bulletin of the American Physical Society
2019 Fall Meeting of the APS Division of Nuclear Physics
Volume 64, Number 12
Monday–Thursday, October 14–17, 2019; Crystal City, Virginia
Session RK: Nuclear Reactions: Hadrons / Light Ions |
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Chair: Heather Crawford, Lawrence Berkeley National Laboratory Room: Salon F/G |
Thursday, October 17, 2019 8:30AM - 8:42AM |
RK.00001: Spin responses to pion quasifree acattering. R. J. Peterson Parity conservation for the scattering of spin zero beams implies only transverse (S x q) spin transfer. This allows a decomposition of spin transfer S$=$0 and S$=$1 in terms of elementary spin amplitudes, similar to use of the Rosenbluth decomposition as used for relativistic electron scattering. For pion beams these amplitudes are known for scattering and charge exchange on nucleons, so a separation of spin and nonspin single nucleon responses is possible for quasifree pion scattering from nucleons within complex nuclei. A large body of pion quasifree data, with and without charge exchange, allows single-nucleon responses of complex nuclei to be determined across a wide range of nuclei for several pion beam energies. Nonspin intercepts and transverse spin slopes will be presented to test this concept for consistency and a summary will be provided. [Preview Abstract] |
Thursday, October 17, 2019 8:42AM - 8:54AM |
RK.00002: Inelastic reaction of 14 MeV neutrons from 7Li Chad Forrest Results of measurements are reported for the double-differential cross section $\left\langle {d^{2}\sigma \mathord{\left/ {\vphantom {\sigma {\mbox{d}E_{\mbox{n}} \mbox{d}\Omega_{\mbox{n}} }}} \right. \kern-\nulldelimiterspace} {\mbox{d}E_{\mbox{n}} \mbox{d}\Omega_{\mbox{n}} }} \right\rangle_{0^{\circ}<\theta <7.4^{\circ}} $ for the inelastic scattering and reaction of 14-MeV neutrons with $^{\mathrm{7}}$Li. In the experiment, the bright neutron source ($L=$ 10$^{\mathrm{24\thinspace }}$s$^{\mathrm{-1}})$ created by the OMEGA pulsed Laser System\footnote{ T. R. Boehly \textit{et al}., Opt. Commun. \textbf{133}, 495 (1997).}, in inertially confined DT thermonuclear fusion reactions was used to irradiate an isotropically separated $^{\mathrm{7}}$Li target. Absolute yields and energy spectra of scattered neutrons and reactions were detected with a sensitive high-dynamic-range neutron time-of-flight spectrometer. In a forward-angle geometry $\left( {\theta =0^{\circ}\;\mbox{to}\;7.4^{\circ}} \right),$ the differential neutron cross section, measured for the neutron energy range 0.5 MeV $\le $ E$_{\mathrm{n}}\le $ 6 MeV, shows significant deviations from evaluated data in the nuclear database. This material is based upon work supported by the Department of Energy National Nuclear Security Administration under Award Number DE-NA0003856. [Preview Abstract] |
Thursday, October 17, 2019 8:54AM - 9:06AM |
RK.00003: Effect of nuclear transparency from the ($p$,2$p)$ measurements on 6Li and 12C at 1 GeV. Vitaly Baturin, Eugeny Komarov, Vladimir Nelyubin, Valentine Sulimov, Vladimir Vikhrov We studied the production of protons to the backward direction in ($p$,2$p)$ reactions on~ 6Li and 12C, accompanied by a proton emitted into the forward hemisphere. The momenta of the final two protons were measured in a wide range with the two-arm time-of-flight spectrometer. For each event we reconstructed the mass of the intermediate off-shell particles. We have discovered a strong narrow dip in the mass spectra of intermediate mesons at the mass of the real pion. We explain this effect as an abrupt decrease of the absorption probability for on-shell mesons (the pion--nuclear transparency). [Preview Abstract] |
Thursday, October 17, 2019 9:06AM - 9:18AM |
RK.00004: L/T separated cross sections and beam asymmetries in kaon electroproduction above the resonance region Mireille Muhoza, Richard Trotta The 12 GeV JLab beam energy and the new Super-High Momentum Spectrometer (SHMS) in Hall C have enabled measurements of precision longitudinal-transverse separated cross sections in exclusive $K^+$ production from the proton above the resonance region. The data acquired by experiment E12-09-011, and the anticipated L/T separated cross sections will be an important step forward in understanding the nonperturbative structure of hadrons including strangeness and the transition from hadronic to partonic degrees of freedom in exclusive processes. Kaons were detected in the SHMS in coincidence with scattered electrons in the HMS. Kaon-proton separation was provided by a threshold aerogel detector and kaon-pion separation by a gas Cherenkov detector. Data were taken in near-parallel kinematics at two electron beam energies. Fitting the azimuthal angle dependence of the measured unpolarized cross section allows for a full separation of the structure functions $\sigma_L$, $\sigma_T$,$\sigma_{LT}$ and $\sigma_{TT}$ . The beam single spin asymmetry from a longitudinally polarized beam leads to a fifth structure function $\sigma_{\mathrm{LT}^{'}}$ . Kaon and pion asymmetries were acquired at ${Q^2}=3.0$, W=2.32, x=0.40. I will give an overview of the experiment and show initial results. [Preview Abstract] |
Thursday, October 17, 2019 9:18AM - 9:30AM |
RK.00005: Deuteron-alpha scattering: separable vs nonseparable Faddeev approach Linda Hlophe, Lei Jin, Charlotte Elster, Andreas Nogga, Filomena Nunes, Darius Jurciukonis, Arnas Deltuva Deuteron-induced nuclear reactions are an essential tool for probing nuclear structure as well as extracting quantities of astrophysical interest. Those (d,p) reactions may be viewed as three-body reactions and described with Faddeev techniques. Specifically, the Alt-Grassberger-Sandhas (AGS) formulation of the Faddeev equations is adopted in this work. A great simplification of the Faddeev-AGS equations occurs if the subsystem interactions are of separable form. However, it needs to be demonstrated that observables calculated based on separable interactions agree exactly with those based on nonseparable forces. We thus use the example of deuteron-alpha scattering to benchmark the separable expansion approach to solving the Faddeev equations without the Coulomb potential. To do so, elastic as well as breakup observables are calculated and compared to results in which the interactions in the two-body sub-systems are represented by separable interactions derived in the Ernst-Shakin-Thaler (EST) framework. We find that the calculations based on the original interactions and their separable presentations give results that are in excellent agreement. [Preview Abstract] |
Thursday, October 17, 2019 9:30AM - 9:42AM |
RK.00006: The Focal Plane Detector for the John D. Fox Accelerator Laboratory Split-pole Spectrograph Juan Esparza A new focal plane detector for the re-commissioned Super-Enge split-pole spectrograph has been designed and currently being built at the John D. Fox Accelerator Laboratory at Florida State University. Based on a design from Argonne National Laboratory [1], this focal plane detector system is designed to resolve individual elements and isotopes of medium weight. It consists of a position-sensitive parallel-plate avalanche counter (PPAC), followed by a Bragg curve detector (BCD), both of which are gas filled. The PPAC features gridded foils which has been shown by the Triangle Universities Nuclear Laboratory to yield sub-millimeter spatial resolution [2]. The energy, nuclear charge, and angle of incidence of particles can all be measured in the BCD. This detector will be characterized and calibrated upon completion of construction. \newline \newline [1] K.E. Rehm and F.L.H. Wolfs, Nucl. Instr. Meth. A273 (1988) 262-272 \newline [2] C. Marshall, et al., \textit{IEEE Trans. Instr. Meth.}, Volume PP, Issue 99, (2018), 1-14 [Preview Abstract] |
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