Bulletin of the American Physical Society
2013 Fall Meeting of the APS Division of Nuclear Physics
Volume 58, Number 13
Wednesday–Saturday, October 23–26, 2013; Newport News, Virginia
Session CF: Reactions: Heavy Ion |
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Chair: Michael Thoennessen, Michigan State University Room: Blue Point II |
Thursday, October 24, 2013 8:30AM - 8:42AM |
CF.00001: Measuring the partial width of the $^{56}$Ni proton-capture resonance through (d,n) with VANDLE and MoNA-LISA William Peters, R. Grzywacz, M. Madurga, S. Paulauskas, S. Taylor, J. Allen, J.A. Cizewski, B. Manning, M.E. Howard, D.W. Bardayan, S.D. Pain, R.C.C. Clement, S. Ilyushkin, P.D. O'Malley, R. Ikeyama, R.L. Kozub, K.D. Long, Z.J. Bergstrom, P.A. DeYoung, W.F. Rogers, J. Smith, M. Jones, T. Baumann, M. Thoennessen Due to the long half-life of $^{56}$Ni and the low proton threshold of $^{57}$Cu, the (p,$\gamma )$ reaction on $^{56}$Ni is the linchpin reaction for heavier elements in the \textit{rp} process of explosive nucleosynthesis. A new attempt to measure the proton partial width of the excited 1/2$^{-}$ state in $^{57}$Cu and to indirectly extract the proton-capture resonance strength was performed at the National Superconducting Cyclotron Laboratory using the Versatile Array of Neutron Detectors at Low Energy (VANDLE) along with the MoNA-LISA neutron array. The VANDLE setup of digitizing electronics was event-matched to the MoNA-LISA-Sweeper data acquisition system. After a test run with a stable $^{40}$Ca beam, a beam of $^{56}$Ni impinged onto a deuterated polyethylene target inducing (d,n) transfer reactions to predominantly single-proton states in $^{57}$Cu. These experiments were the commissioning experiments for VANDLE with a transfer reaction. Details of the unique experimental setup will be presented as well as current analysis of the data with both $^{40}$Ca and $^{56}$Ni beams. [Preview Abstract] |
Thursday, October 24, 2013 8:42AM - 8:54AM |
CF.00002: Production cross sections from $^{82}$Se fragmentation as indications of shell effects close to the neutron drip-line O.B. Tarasov, M. Portillo, D.J. Morrissey, A.M. Amthor, T. Baumann, D. Bazin, J.S. Berryman, B.A. Brown, G. Chubarian, N. Fukuda, A. Gade, T.N. Ginter, M. Hausmann, N. Inabe, T. Kubo, J. Pereira, B.M. Sherrill, A. Stolz, C. Sumithrarachichi, M. Thoennessen, D. Weisshaar Production cross sections for neutron-rich nuclei from the fragmentation of a $^{82}$Se beam at 139 MeV/u with beryllium and tungsten targets have been measured for a large number of nuclei. The nuclides $^{64}$Ti,$^{67}$V,$^{69}$Cr,$^{72}$Mn, the most neutron-rich isotopes of the elements $22\le Z\le 25$, have been observed for the first time. The measured cross sections were used to search for trends in the structure of nuclei around $^{54}$Ca and were compared with Abrasion-Ablation calculations under the assumption of various mass models. The results confirm our previous investigations from a similar measurement using a $^{76}$Ge beam and can be explained with a modified GXPF1B Hamiltonian where the energy of the $f_{5/2}$ orbit is lowered by 0.5 MeV for neutron-rich isotopes around $Z$=20. The subshell gap at $N$=34 is reduced compared to the unmodified Hamiltonian. [Preview Abstract] |
Thursday, October 24, 2013 8:54AM - 9:06AM |
CF.00003: Modeling Timescale of Equilibration in Dinuclear Systems Krystin Stiefel, Zach Kohley The break-up and N/Z equilibration processes of dinuclear systems can be utilized to place constraints on the density dependence of the symmetry energy. In semi-peripheral heavy-ion collisions, excited projectile-like fragments can be formed which decay through binary breakup. The rotation of this binary system can be used to probe the timescale of the N/Z equilibration of the system. A previous experiment performed by the Indiana University research group using this approach has shown that initial neutron gradients can have an effect on the equilibration process [1]. Simulations using the Constrained Molecular Dynamics (CoMD) model have been executed and compared to experimental data. The comparison will allow for a better understanding of the timescale of equilibration. \\[4pt] [1] K. Brown et. al. Phys. Rev. C \textbf{87}, 061601 (2013). [Preview Abstract] |
Thursday, October 24, 2013 9:06AM - 9:18AM |
CF.00004: Thermodynamics of Asymmetric Nuclear Material Alan McIntosh, A. Bonasera, P.J. Cammarata, K. Hagel, Z. Kohley, L. Heilborn, J. Mabiala, L.W. May, P. Marini, A. Raphelt, G.A. Souliotis, S. Wuenschel, A. Zarrella, H. Zheng, S.J. Yennello The nuclear caloric curve is observed to depend on the neutron-proton asymmetry. Three independent methods, each with multiple probes, are used to extract the temperatures of excited emitting sources. A linear decrease in the temperature with increasing neutron excess is observed for all 12 probes studied. Comparison of these results to theoretical model calculations may allow further characterization of the nuclear equation of state, in particular the asymmetry energy. [Preview Abstract] |
Thursday, October 24, 2013 9:18AM - 9:30AM |
CF.00005: Experimental techniques to use the (d,n) reaction for spectroscopy of low-lying proton-resonances Sean Kuvin Studies of rp-process nucleosynthesis in stellar explosions show that establishing the lowest $l=0$ and $l=1$ resonances is the most important step to determine reaction rates in the astrophysical rp-process path. At the RESOLUT facility, we have used the $(d,n)$ reaction to populate the lowest p-resonances in $^{26}Si$, and demonstrated the usefulness of this approach to populate the resonances of astrophysical interest [1]. In order to establish the $(d,n)$ reaction as a standard technique for the spectroscopy of astrophysical resonances, we have developed a compact setup of low-energy Neutron-detectors, ResoNEUT and tested it with the stable beam reaction $^{12}C(d,n)^{13}N$ in inverse kinematics. Performance data from this test-experiment and future plans for this setup will be presented. [Preview Abstract] |
Thursday, October 24, 2013 9:30AM - 9:42AM |
CF.00006: Elastic scattering and neutron transfer of the $^{26}$Mg + $^{13}$C reaction Matthew McCleskey, A. Alharby, A. Banu, V.Z. Goldberg, E. McCleskey, B.T. Roeder, A. Spiridon, L. Trache, R.E. Tribble Direct proton capture on $^{26}$Si is of interest for its role in the destruction of $^{26}$Si that would otherwise be available to $\beta$+ decay into $^{26m}$Al. This is part of the network of reactions that influence the production and destruction of the important astrophysical observable $^{26}$Al. The $^{13}$C($^{26}$Mg,$^{27}$Mg)$^{12}$C reaction at 12 MeV/nucleon has been measured at Texas A$\&$M University Cyclotron Institute with the aim to determine ANC for $^{27}$P $\leftrightarrow$ p + $^{26}$Si via mirror symmetry. Details of the experiment as well as preliminary results will be presented. [Preview Abstract] |
Thursday, October 24, 2013 9:42AM - 9:54AM |
CF.00007: Production cross sections of $^{20}$Ne-induced reactions Mohammad S. Sabra Production cross sections for the reaction of $^{20}$Ne on C, Al, Cu, Sn and Pb targets at 400MeV/u are calculated using the modified statistical model with final state interaction (SMFSI). The calculations of SMFSI are in good agreement with the available experimental data and consistent with the odd-even effects. Comparison with different simulation codes will be presented and discussed. [Preview Abstract] |
Thursday, October 24, 2013 9:54AM - 10:06AM |
CF.00008: Simulation studies of the sPHENIX calorimeters at RHIC Liang Xue, Xiaochun He The study of jet quenching and di-hadron correlation provide key knowledge for the coupling of the quark gluon plasma (QGP), and the mechanism of rapid equilibration. During past three years, the current PHENIX collaboration has developed its decade's upgrade refer as sPHENIX. The sPHENIX will incorporate two new electromagnetic (EMCal) and hadronic (HCal) calorimeters with a large pseudo-rapidity range ($|\eta| < 1.$), and full azimuthal coverage, that will enable a systematic study of jets in QGP. In this talk, we present the results of single particle simulation with Geant 4 for the sPHENIX EMCal and HCal with planar and tilt plates geometries. The hadronic rejection power and the electron/hadron separation capability will also be presented. [Preview Abstract] |
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