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 MG: Nuclear Structure II |
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Chair: Masaaki Kimura, Hokkaido University Room: King's 3 |
Saturday, October 11, 2014 2:00PM - 2:15PM |
MG.00001: Effect of tensor interactions in 16O studied via (p,d) reaction Hooi Jin Ong, Isao Tanihata, Atsushi Tamii, Takayuki Myo, Kazuyuki Ogata, Mitsunori Fukuda, Kiyomi Ikeda, Daiki Ishikawa, Takahiro Kawabata, Hiroaki Matsubara, Kensaku Matsuta, Mototsugu Mihara, Takuma Naito, Daiki Nishimura, Yoko Ogawa, Akira Ozawa, Danyang Pang, Harutaka Sakaguchi, Kimiko Sekiguchi, Tomokazu Suzuki, Manami Taniguchi, Hiroshi Toki, Yusuke Yasuda, Masaru Yosoi, Juzo Zenihiro We report a possible evidence of tensor interactions in $^{16}$O observed via high-momentum (p,d) reaction. We measured the differential cross sections populating the ground states and several low-lying excited states in $^{15}$O. Comparing the ratios of the cross sections for the 5/2$^+$ and the $3/2^-$ excited states to the one for the ground state over a wide range of momentum transfer, we found a marked enhancement of the ratio for the 5/2$^+$ state as compared to that for the $3/2^-$ state. The observation is consistent with large components of high-momentum neutrons in the initial ground-state configurations explainable by the tensor interactions. [Preview Abstract] |
Saturday, October 11, 2014 2:15PM - 2:30PM |
MG.00002: Role of tensor force in Be isotopes with tensor-optimized shell model Takayuki Myo, Atsushi Umeya, Kaori Horii, Hiroshi Toki, Kiyomi Ikeda We investigate the role of tensor force in Be isotopes. We use the method of the tensor-optimized shell model, in which the strong tensor correlation is involved explicitly in the wave function by including the 2p2h excitations with high momentum. The short-range correlation is treated with central-UCOM. We employ the bare nucleon-nucleon force such as Argonne potential and examine how the bare tensor force determines the structures of Be isotopes such as the energy spectrum and the configuration mixing of the single-particle states. We investigate the tensor contribution of each energy level and clarify its relation to the important configurations of the single-particle states. We also discuss the alpha clustering correlation in neutron-rich Be isotopes on the basis of the two alpha-developed structure in 8Be. [Preview Abstract] |
Saturday, October 11, 2014 2:30PM - 2:45PM |
MG.00003: Ab-initio strength functions in light nuclei Michael Kruse, W. Erich Ormand, Calvin Johnson Strength functions are an excellent tool to determine the collective excitation mechanism of a nucleus in the presence of electromagnetic fields. Since the discovery of the giant-dipole resonance in heavy nuclei much theoretical and experimental work has been devoted to studying strength functions. We present strength function calculations for the light nuclei A$=$6, A$=$10 and C-12 within an ab initio framework. We show results for the isoscalar and isovector monopole modes as well as the electric- and magnetic dipole response. The calculations are performed with the No-Core Shell Model. As input we use an isoscalar Hamiltonian derived from a similarity renormalized two-body chiral N3LO interaction and perform the calculation for basis-space sizes up to Nmax$=$14 for A$=$6 and Nmax$=$8 for A$=$10. Further, we present evidence supporting the Brink hypothesis that if a giant dipole resonance is found for the ground-state then the excited states will also exhibit such a resonance. [Preview Abstract] |
Saturday, October 11, 2014 2:45PM - 3:00PM |
MG.00004: Quantum Monte Carlo calculations of electromagnetic transitions in light nuclei Saori Pastore, Rober Wiringa, Rocco Schiavilla, Steven Pieper Recently, we presented ab initio quantum Monte Carlo calculations of magnetic moments and M1 transitions in $A \le 10$ nuclei, which include two-body meson-exchange currents' contributions of one- and two-pion range, derived from chiral effective field. These corrections are found to always improve the theoretical predictions, leading to a very good agreement with the experimental data. Here, we report on a study, carried out within the same framework, of M1 transitions in low-lying states of $^8$Be. We also present a number of E2 transition calculations, evaluated in impulse approximation, with emphasis on transitions involving the $^8$Be resonant excited states at $\sim 3$ MeV and $\sim 11$ MeV. [Preview Abstract] |
Saturday, October 11, 2014 3:00PM - 3:15PM |
MG.00005: E1 and M1 strength in $^{76}$Ge and $^{76}$Se from NRF experiments N. Cooper, V. Werner, R.S. Ilieva, P. Humby, P.M. Goddard, G. Rusev, A.P. Tonchev, D. Savran, J. Beller, N. Pietralla, C. Romig, M. Scheck, M. Zweidinger, B.P. Crider, S.W. Yates Dipole strength below the neutron separation energy of $^{76}$Ge and $^{76}$Se has been measured in a series of nuclear resonance fluorescence experiments at the TU Darmstadt and the Triangle Universities Nuclear Laboratory. Details of the data are compared with those expected from various strength functions under the assumption of the validity of the Brink hypothesis and Gaussian transition matrix elements. Additionally, these data are used to help constrain parameters in the Interacting Boson Model-2 for these nuclei involved in large-scale neutrino-less double-beta decay studies. [Preview Abstract] |
Saturday, October 11, 2014 3:15PM - 3:30PM |
MG.00006: Uncertainty Quantification for Nuclear Density Functional Theory Jordan McDonnell, Nicolas Schunck, Witold Nazarewicz, Dave Higdon, Jason Sarich, Stefan Wild Nuclear density functional theory exhibits good overall agreement with measured nuclear masses for medium-mass to heavy nuclei. But the predictions of various models diverge substantially near the neutron and proton drip lines. Quantifying the theory's inherent uncertainty is essential for making reliable predictions. Through a Bayesian analysis, we calculate the theoretical uncertainty for nuclear masses obtained with a Skyrme-class energy density functional. We also assess whether a recent set of mass measurements of neutron-rich nuclei reduces the uncertainty in this model's predictions near the neutron drip line. [Preview Abstract] |
Saturday, October 11, 2014 3:30PM - 3:45PM |
MG.00007: Shell model approach for nuclei with mass around 220 Yukiko Kaiura, Naotaka Yoshinaga, Koji Higashiyama Ra and Th isotopes with mass around 220 belonging to a transitional region between spherical and deformed regions have fascinated our interest from the past. In particular, since a large number of negative parity states are observed in low-lying states, collective octupole correlations are supposed to be important. In this talk we report the nuclear structure of Po, Rn, Ra and Th isotopes in terms of the pair truncated shell model, the basic ingredients of which consist of nuclear collective models. The $^{208}$Pb is considered as the doubly-magic core. The conventional pairing plus quadrupole interaction is employed. Energy levels and electric transitions are compared between theory and experiment. [Preview Abstract] |
Saturday, October 11, 2014 3:45PM - 4:00PM |
MG.00008: Charge radii and nuclear moments of neutron-deficient potassium isotopes K. Minamisono, B.R. Barquest, G. Bollen, M. Hughes, R. Strum, D. Tarazona, H.B. Asberry, K. Cooper, K. Hammerton, A. Klose, P.F. Mantica, D.J. Morrissey, Ch. Geppert, J. Harris, R. Ringle, J.A. Rodriguez, D.M. Rossi, C.A. Ryder, A. Smith, S. Schwarz, C. Sumithrarachchi The monotonic change of charge radii of K isotopes across $N$ = 20 suggests a reduction of the shell gap. A systematic study of the charge radii and ground state magnetic and quadrupole moments of neutron-deficient $^{35-37}$K isotopes is underway at the BEam COoling and LAser spectroscopy (BECOLA) facility at NSCL/MSU to investigate the anomalous trend in charge radii. The K isotopes were produced by fragmentation of a $^{40}$Ca beam, thermalized in a linear gas cell, extracted at an energy of 30 keV, and transported to BECOLA. The K ion beam was cooled and bunched, and neutralized in a Na vapor cell. Laser-induced fluorescence was detected as a function of the Doppler-tuned laser frequency and time relative to the release of the beam bunch. The beta-NMR technique was used to determine ground-state nuclear moments, where hyperfine splittings are too small to resolve using collinear laser spectroscopy. [Preview Abstract] |
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