Bulletin of the American Physical Society
4th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 59, Number 10
Tuesday–Saturday, October 7–11, 2014; Waikoloa, Hawaii
Session CE: Light Nucleon-induced Reactions |
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Chair: Robert Casperson, Lawrence Livermore National Laboratory Room: King's 1 |
Wednesday, October 8, 2014 7:00PM - 7:15PM |
CE.00001: Nonlocal Potentials in Nuclear Reactions Luke Titus, Filomena Nunes In this work we investigate the effect of nonlocality for single-channel bound and scattering states, as well as in transfer ($p,d)$ cross sections. We solve the scattering and bound state equations for nonlocal interactions of the Perey-Buck type [1]. Using the distorted wave Born approximation, we construct the $T $matrix for ($p,d)$ on $^{17}$O, $^{41}$Ca, $^{49}$Ca, $^{127}$Sn, $^{133}$Sn, and $^{209}$Pb at 20 and 50 MeV. If local optical potentials are used in the analysis of experimental ($p,d$) cross sections, as compared to the analysis with nonlocal potentials, the spectroscopic factors can be affected by approximately 20{\%}. The Perey correction factor does offer an improvement over taking a direct local equivalent solution. However, if the desired accuracy is to be better than 10{\%}, the exact solution of the nonlocal equation should be pursued. \\[4pt] [1] Titus and Nunes, Phys. Rev. C\textbf{89}, 034609 (2014). [Preview Abstract] |
Wednesday, October 8, 2014 7:15PM - 7:30PM |
CE.00002: Coupled-Channel Computation of Direct Neutron Capture on Non-Spherical Nuclei Goran Arbanas, Ian Thompson, Jutta Escher, Filomena Nunes, Charlotte Elster, Shi-Sheng Zhang Models of direct neutron capture of neutrons have so far accounted for the effects of non-spherical nuclei either in the incoming wave functions (via non-spherical optical model potentials), {\em or} in the final bound states (via non-spherical real potential wells), but not in both. Since it is known that spherical optical potentials do not give a good reproduction of low energy neutron-scattering observables of deformed nuclei, we have performed calculations in which the initial and final states are both treated in a self-consistent, non-spherical-nucleus picture. We have done this in the coupled-channels model of nuclear reactions implemented in the FRESCO code [1] by using the same deformation-length for the couplings to the rotational-band states in the incoming {\em and} the final state configurations. We compute direct capture using this method for even-mass calcium isotopes $^{40,42,44,46,48}$Ca to study the effect across the two closed neutron shells, for neutron-rich even-mass tin isotopes relevant to models of astrophysical nucleosynthesis, and for $^{56}$Fe that is an important structural material used in nuclear applications. \\[4pt] [1] I. J. Thompson, Coupled reaction channels calculations in nuclear physics, Computer Physics Reports, 7 (1988), pp. 167 - 212. [Preview Abstract] |
Wednesday, October 8, 2014 7:30PM - 7:45PM |
CE.00003: Effects of chiral three nucleon forces on elastic scattering Masakazu Toyokawa, Kosho Minomo, Michio Kohno, Masanobu Yahiro An important current issue in nuclear physics is to clarify the roles of the three-nucleon force (3NF). Recently, two-nucleon force (2NF) and 3NF were systematically and clearly defined by chiral effective field theory, although a phenomenological 3NF was known to reduce cross sections of nucleus-nucleus elastic scattering largely at backward angles [1]. In this talk, we investigate the roles of chiral-3NF in nucleon-nucleus and nucleus-nucleus scattering. The optical potential calculated from chiral 2NF is found to be close to that from Bonn-B 2NF. We then introduce the chiral-3NF effects to the local G-matrix (Melbourne interaction) [2] constructed from Bonn-B 2NF. Chiral 3NF makes the folding potential less attractive and more absorptive. These effects reduce cross sections at backward angles particularly for AA scattering. The novel property for the imaginary part is originated in the enhancement of tensor correlations due to chiral 3NF.\\[4pt] [1] T. Furumoto et.al. Phys.Rev.C 79, 011601(R)(2009).\\[0pt] [2] K. Amos et.al. Adv.in Nucl.Phys.Vol.25, p. 275.(2000). [Preview Abstract] |
Wednesday, October 8, 2014 7:45PM - 8:00PM |
CE.00004: Elastic deuteron scattering and optical model parameters at 100 MeV/u D. Patel, U. Garg, M. Itoh, H. Akimune, C. Iwamoto, A. Okamoto, G.P.A. Berg, K. Howard, J.T. Matta, E. Morgan, K.W. Schlax, M. White, M. Fujiwara, F. Takahashi, M. Yosoi, M.N. Harakeh, T. Kawabata, T. Murakami, K. Kawase, T. Sako The advent of the radioactive ion beam facilities would render possible the measurement of giant resonances in nuclei far from the stability line. The centroid energy of the isoscalar giant monopole resonance and the isoscalar giant dipole resonance play an important role in constraining the nuclear incompressibility, an important parameter in nuclear equation of state. However, these experiments would have to be done in inverse kinematics and the most appropriate target appears to be deuteron gas in an AT-TPC. It thus becomes important to explore the features of deuteron optical model at high energy with a view of obtaining higher cross-sections. Elastic scattering measurements have been made on 24Mg, 28Si, 58Ni, 90Zr, 116Sn and 208Pb nuclei using 100 MeV/u deuteron beam at RCNP, Osaka University, Japan. Various features of the optical model parameters will be discussed. [Preview Abstract] |
Wednesday, October 8, 2014 8:00PM - 8:15PM |
CE.00005: Cross-sections for populating excited states in $^{150-153}$Sm via the (p,d) and (p,t) reactions P. Humby, A. Simon, C.W. Beausang, K. Gell, T. Tarlow, G. Vyas, T.J. Ross, R.O. Hughes, J.T. Burke, R.J. Casperson, J. Koglin, S. Ota, J.M. Allmond, M. McCleskey, E. McCleskey, A. Saastamoinen, R. Chyzh, M. Dag Light ion transfer reactions were used to populate low/medium spin states in $^{150-154}$Sm via the (p,p$'\gamma$), (p,d$\gamma$) and (p,t$\gamma$) reactions. The 25 MeV proton beam, with an average current of 1 nA, was provided by the K-150 Cyclotron at the Cyclotron Institute of Texas A\&M University. The outgoing charged particles and coincident gamma-rays were detected using the STARLiTeR arrays. STARs (Silicon Telescope Array for Reaction studies), a highly segmented $\Delta$E-E silicon telescope, provides particle identification as well as the energies, times and angular distributions of the protons, deuterons and tritons in the exit channels. LiTeR (Livermore Texas Richmond array), an array of six BGO shielded HPGe clover detectors, records the energy, time and angular distribution of the coincident gamma rays, providing excellent selectivity of the states of interest. Preliminary results for the cross-sections for direct population of states in $^{150-153}$Sm will be presented. [Preview Abstract] |
Wednesday, October 8, 2014 8:15PM - 8:30PM |
CE.00006: ABSTRACT WITHDRAWN |
Wednesday, October 8, 2014 8:30PM - 8:45PM |
CE.00007: Coincident Measurements of 176Lu Level Structure for Nuclear Astrophysics using ICEBall and GEORGINA Anthony Battaglia, Wanpeng Tan, Ani Aprahamian, Roza Avetisyan, Clark Casarella, Armen Gyurjinyan, Scott Marley, Andrew Nystrom, Nancy Paul, Kevin Siegl, Karl Smith, Mallory Smith, Sabrina Strauss The stellar production of $^{176}$Lu is synthesized via the s-process only. There is a long lived ground state (K=7) and short lived isomer (K=1), which do not communicate directly, however if there is an indirect communication between these levels it will affect the decay of $^{176}$Lu in astrophysical environments.\footnote{K.T. Lesko et al. Phys. Rev. C, 77, 2850 (1991)} Recently, new measurements have found several low-lying intermediate states that indirectly communicate to both the ground and isomeric state.\footnote{G.D. Dracoulis et al. Phys. Rev. C, 81, 011301 (2010)} Thus, to further investigate the low level structure of $^{176}$Lu, states were populated using a $^{176}$Yb(p,n) reaction with a 7.75 MeV bunched beam provided by the FN Tandem at the University of Notre Dame. Both conversion electrons and gamma-rays were detected in coincidence between the ICEBall array and two single-crystal germanium detectors from the GEORGINA array. The results from this experiment will be discussed. This work was supported by the National Science Foundation under contract number NSF PHY-1068192. [Preview Abstract] |
Wednesday, October 8, 2014 8:45PM - 9:00PM |
CE.00008: Nuclear structure studies of 195Au and 196Au Armen Gyurjinyan, Anthony Battaglia, Clark Casarella, Andrew Nystrom, Kevin Siegl, Karl Smith, Mallory Smith, Sabrina Strauss, Wanpeng Tan, Ani Aprahamian The Interacting Boson Model (IBM) theory is widely used to describe nuclear structure of heavy even-even nuclei. The model was extended to odd-A and odd-odd nuclei structure studies with supersummetric transformations. The best quartet of nuclei to test the supersymmetry transformations is $^{194}$Pt, $^{195}$Pt, $^{195}$Au and $^{196}$Au. The IBM describe the well-known spectra of $^{194}$Pt, and then the supersymmetric transformations can predict low-lying levels with negative parity in $^{195}$Pt, $^{195}$Au, $^{196}$Au. We used $^{195}$Pt(p,n), $^{196}$Pt(p,n) and $^{196}$Pt(p,2n) reactions to produce $^{195}$Au and $^{196}$Au at the University of Notre Dame Nuclear Science Laboratory. The beam was 7.75MeV and 12 MeV bunched proton beam respectively. The conversion electron spectroscopy was carried out using the ICEBall array mini-orange detectors and two high purity germanium detectors with 109{\%} efficiency for gamma spectroscopy. The results of experiment will be presented. [Preview Abstract] |
Wednesday, October 8, 2014 9:00PM - 9:15PM |
CE.00009: Dirac coupled channel analyses of the 800MeV proton inelastic scatterings from $^{22}$Ne Sugie Shim, Moon-Won Kim Dirac analyses are performed for the 800MeV proton inelastic scatterings from an s-d shell nucleus $^{22}$Ne using the optical potential model. Dirac coupled channel equations are solved numerically using the sequential iteration method by varying the optical potential and deformation parameters, using a computer code called ECIS. Dirac equations are reduced to obtain Schroedinger-like second-order differential equations and the obtained effective central and spin-orbit optical potentials are analyzed and compared with those of other s-d shell nuclei such as$^{20}$Ne, $^{24}$Mg and $^{26}$Mg. It is found that relativistic analyses based on Dirac equation could describe the experimental data for the 800 MeV proton inelastic scatterings from $^{22}$Ne reasonably well. The surface-peaked phenomena are observed for the real parts of effective central potentials for the scattering from $^{22}$Ne, as shown in the case of $^{20}$Ne and $^{24}$Mg. Dirac phenomenological results for the deformation parameters for 2$^{+}$ and 4$^{+}$ states of $^{22}$Ne agree well with the results of the nonrelativistic calculation using the same W-S potential shape. [Preview Abstract] |
Wednesday, October 8, 2014 9:15PM - 9:30PM |
CE.00010: Development of neutron polarization measurement system for studying the medium effect on NN interaction Jumpei Yasuda Modification of nucleon and meson properties in nuclear medium is one of the most interesting topics in nuclear physics. To investigate the medium effect on NN interaction, quasi-elastic reaction is one of the most powerful tool. Especially, the spin observables are very useful since it is insensitive to distortion effect. For the proton-proton interaction, the analyzing power and polarization transfer have been measured for exclusive (p,2p) reaction. On the other hand, for the proton-neutron interaction, the polarization transfer have been measured only for inclusive (p,n) reaction. Therefore, we plan to measure the polarization transfer for exclusive (p,np) reaction. To achieve the measurement, we developed the neutron polarization measurement system for (p,np) reaction, which has following two component; (1) neutron polarization measurement; (2) exclusive measurement. For the neutron polarization measurement, we have reconstructed the neutron polarimeter NPOL3. We have calibrated the new NPOL3 by using the polarized neutron from 2H(p,n) reaction and obtained the effective analyzing power $Ay_{\rm eff}=0.127$. For the exclusive measurement, we used the LAS spectrometer for recoil proton detection and achieved the energy resolution of 6 MeV. [Preview Abstract] |
Wednesday, October 8, 2014 9:30PM - 9:45PM |
CE.00011: Spatial measure of reaction size in proton scattering Masashi Tomita, Masataka Iwasaki, Reiji Otani, Makoto Ito The Hoyle state in $^{12}$C has a developed 3$\alpha $ cluster structure, and its matter radius is expected to be enhanced by about 50 percent in comparison to the radius of the ground state. However, the enhanced radius of the 3$\alpha $ state is not confirmed experimentally. Recently we have proposed ``the scattering radius,'' which characterizes a spatial size of an exclusive reaction in a general two-body scattering problem. In the present study, we perform the microscopic coupled-channel calculation for the proton $+ ^{12}$C system, and the scattering radii for the inelastic scatterings to various excited states are evaluated. The proton - $^{12}$C nuclear interactions are derived from the folding model, which employs the density-dependent M3Y effective nucleon-nucleon interaction and the $^{12}$C transition densities, obtained from the microscopic 3$\alpha $ cluster model. We have calculated the angular distributions for the inelastic scattering to the collective states (2$_{1}^{+}$ and 3$_{1}^{-}$) and the 3$\alpha $ cluster states (0$_{2}^{+}$ and 2$_{2}^{+}$). The scattering radii are derived for the individual channels, and we have confirmed the strong enhancement of the scattering radii in the 3$\alpha $ channels, which is consistent to the picture of the nuclear $\alpha $ condensation. In the present report, we will explain the enhancement of the scattering radii in the 3$\alpha $ channels in connection to the matter radii of the 3$\alpha $ cluster states. [Preview Abstract] |
Wednesday, October 8, 2014 9:45PM - 10:00PM |
CE.00012: ABSTRACT WITHDRAWN |
Wednesday, October 8, 2014 10:00PM - 10:15PM |
CE.00013: ABSTRACT WITHDRAWN |
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