Bulletin of the American Physical Society
5th Joint Meeting of the APS Division of Nuclear Physics and the Physical Society of Japan
Volume 63, Number 12
Tuesday–Saturday, October 23–27, 2018; Waikoloa, Hawaii
Session CA: Cold Dense Matter and Neutron Stars |
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Chair: Tomohiro Uesaka, RIKEN Nishina Center Room: Hilton Kona 4 |
Wednesday, October 24, 2018 7:00PM - 7:45PM |
CA.00001: Impact of nuclear symmetry energy on neutron star structure and crustal oscillations Invited Speaker: Hajime Sotani Neutron stars are a good candidate for studying physics in the extreme states. Since the density inside the star significantly exceeds the normal nuclear density. Considering that the density at the crust-core boundary becomes around (1/3-1) times normal nuclear density, the nuclear properties around the saturation density play an important role in the phenomena inside the crust and in the low-mass neutron star itself. In this presentation, a theoretical approach to the question of how the poorly known density dependence of nuclear symmetry energy affects the mass-radius relation of neutron stars, as well as the eigenfrequencies of crustal torsional oscillations, will be discussed, together with astrophysical implications. In particular, we will show a combination of nuclear saturation parameters, which can express well low-mass neutron stars. With this new parameter, we also discuss the possible maximum mass of neutron stars. In addition, by comparing the frequencies of crustal torsional oscillations to the quasi-periodic oscillations observed in giant flares, we will constrain not only the nuclear saturation parameters but also the neutron star model for one of the giant flares. |
Wednesday, October 24, 2018 7:45PM - 8:30PM |
CA.00002: The EOS of neutron matter and neutron stars Invited Speaker: Stefano Gandolfi Recent advances in experiments of the symmetry energy of nuclear |
Wednesday, October 24, 2018 8:30PM - 9:15PM |
CA.00003: Probing high-momentum protons and neutrons in asymmetric nuclei Invited Speaker: Meytal Duer Without short range interaction, the Pauli exclusion principle causes the majority nucleons (usually neutrons) in an asymmetric nucleus to have higher average momentum than the minority. High-energy electron scattering measurements showed that the short range interaction between the nucleons mainly form correlated high momentum neutron-proton pairs in the nucleus. Thus, in neutron-rich nuclei, protons have greater probability than neutrons to have momentum larger than the Fermi momentum. Based on our new data from CLAS detector at Jefferson Laboratory we claim that this results in protons having higher average momentum than neutrons, i.e., an inversion of the momentum sharing between majority and minority nucleons. |
Wednesday, October 24, 2018 9:15PM - 10:00PM |
CA.00004: Experimental study of the isospin dependence of nuclear incompressibility Invited Speaker: Shinsuke Ota The equation of state (EoS) of nuclear matter not only governs the femto-scale quantum many-body system, namely nuclei, but also plays an important role in the structure of neutron stars, supernova phenomena and neutron-star mergers. In particular, the isospin dependence of EoS has attracted much interest from the viewpoint of the existence of heavy neutron stars. The asymmetric term of incompressibility, Kτ, can be a benchmark for various EoS models because it can be directly deduced from the energies of the isoscalar giant monopole resonance (ISGMR) measured along an isotopic chain. The present value of Kτ is -550±100 MeV from the ISGMRs in tin isotopes [1]. In order to improve the Kτ value, the measurement on the isotopic chain is extended to unstable nuclei. The tin isotope, 132Sn, has been chosen as a flagship for the measurements of unstable tin isotopes because of its large isospin asymmetry and doubly magic nature. A measurement of ISGMR energy in 132Sn was performed at RIBF using a gaseous active target CAT-S. The secondary beam including 132Sn, 133Sb, and 134Te was produced through inflight fission of 238U at an incident energy of 345 MeV/u. Beam particles were identified on an event-by-event basis by measuring the time-of-flight and magnetic rigidity. The typical total beam intensity was 8×105 and 3×105 counts per second at the start point of optics and in front of the CAT-S, respectively. The kinetic energy of 132Sn at the center of the CAT-S was about 100 MeV/u. The CAT-S was filled with 0.4-atm deuterium gas, and the trajectories of beam and recoil particles were simultaneously measured with the CAT-S; the energy spectrum was obtained by using the missing mass method. The bump around 15 MeV was observed that likely corresponds to the ISGMR. The deduced Kτ and the constraint for the EoS and outlook will be discussed. [1]: T. Li et al., Phys. Rev. Let. 99 (2007) 162503
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