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 MF: Nuclear Matter and Nuclear Astrophysics |
Hide Abstracts |
Chair: Jeremy Holt, Texas A&M University Room: Hilton King's 2 |
Saturday, October 27, 2018 2:00PM - 2:15PM |
MF.00001: Equilibration chronometry in two and three bodies dynamically deformed nuclear systems. Alis Rodriguez Manso, Alan B McIntosh, Jerome Gauthier, Kris Hagel, Lauren Heilborn, Andrea Jedele, Aditya Wakhle, Andrew Zarrella, Sherry J Yennello We studied neutron-proton (NZ) equilibration in heavy-ion reactions as function of time. Heavy-ion collisions below the balance energy create a neutron-rich neck zone at the expense of the projectile and target. The neck ruptures multiple times as the reaction partners re-separate, with measurable delays between ruptures. We studied the composition of the two and three largest daughters of the deformed projectile-like fragment (PLF*). Two fragments which are initially dissimilar in NZ composition converge exponentially with consistent rate constants across a wide variety of reaction partners and systems, indicating the equilibration follows first order kinetics. The equilibration chronometry method is robust with respect to the impact of secondary evaporation, background of statistical fragment production and alternative choices of alignment angle definition. To add constraints on the nuclear equation of state we explored how these measurements compare to dynamical transport model calculations. Additionally we studied the three fragments break-up of the PLF* to answer interrogantes regarding simultaneous or double rupture scenario, if the third largest daughter of the PLF* separates first or not, and if the three fragments are aligned in a string of pearls configuration. |
Saturday, October 27, 2018 2:15PM - 2:30PM |
MF.00002: Effective mass constraints from heavy-ion collisions Kyle Wayne Brown, Zbigniew Chajecki, Manyee Betty Tsang, William Gregory Lynch, Juan J Manfredi, Sean R Sweany, Kuan Zhu, Adam Anthony, Jin-Hee Chang, Daniele Dell'Aquila, Chi-En Teh, Jonathan E Barney, Justin B Estee, Chun Yuen Tsang, Mira Ghazali, Om Bhadra Khanal Nucleons in dense nuclear matter appear to have reduced inertial masses due to momentum dependent interactions they experience with other nucleons. This reduction of their masses is often referred to as their effective mass, and at saturation density the masses are reduced to about 70% of their vacuum mass. In asymmetric matter the effective masses of neutrons (n) and protons (p) can be different, leading to an effective mass splitting. The sign and magnitude of this splitting is poorly constrained at densities away from saturation density. Recent experiments at the National Superconducting Cyclotron Laboratory were performed to help constrain this effective mass splitting. By measuring the kinetic energy spectra of n and p, or analogously using measured 3He and 3H, this splitting can be extracted. Collisions of beams of 40,48Ca at 50 and 140 MeV/A impinged on targets of 58,64Ni and 112,124Sn. Light charged particles were detected in the upgraded High-Resolution Array and neutrons were detected in the Large-Area Neuron Array. I will present details about the experiment setup and then discuss some results on the spectral ratios. |
Saturday, October 27, 2018 2:30PM - 2:45PM |
MF.00003: Study of light cluster production in intermediate energetic heavy-RI collision at RIBF Masanori Kaneko The physics motivation of the SpiRIT (SAMURAI Pion-reconstruction and Ion Tracker) collaboration is to place a constraint on the symmetry energy term in the nuclear equation of state at around twice saturation densities. Charged pion ratio in intermediate energetic heavy-ion collisions(HIC) is predicted as a good probe to extract symmetry energy, however, there is still large model dependence. Not only nucleon dynamics but also cluster-cluster correlation in HIC are reported to influence pion production. In order to discuss pion with less uncertainty, it is necessary to understand properties on nucleon and cluster well. We performed the experiment at the RIKEN-RIBF with four kinds of Sn-Sn isotopic collisions at 270 MeV/nucleon in spring 2016. Charged particles were measured and identified by the SpiRIT-TPC in combination with the SAMURAI magnet. Light charged particles(LCP) in HIC could be a possible benchmark to understand cluster property. In this talk, yields of LCP and their dynamics will be discussed. |
Saturday, October 27, 2018 2:45PM - 3:00PM |
MF.00004: The Elasticity of Nuclear Pasta Matthew E Caplan, Andre Da Silva Schneider, Charles J Horowitz The elastic properties of neutron star crusts are relevant for a variety of currently or or near-future observable electromagnetic and gravitational wave phenomena. These phenomena may depend on the elastic properties of nuclear pasta found in the inner crust. This talk will present large scale classical molecular dynamics simulations where we deform nuclear pasta. We report on simulations of idealized samples of nuclear pasta and describe their breaking mechanism and also deform nuclear pasta that is arranged into many domains, similar to what is known for the ions in neutron star crusts. We show that nuclear pasta may be the strongest known material, perhaps with a shear modulus of $10^{30}\,\text{ergs/cm}^3$ and breaking strain greater than 0.1. |
Saturday, October 27, 2018 3:00PM - 3:15PM |
MF.00005: Effects of strong magnetic fields on neutron 3P2 vortices in LS potentials Shigehiro Yasui, Chandrasekhar Chatterjee, Muneto Nitta We face an age that the inner structures of neutron stars can be studied by a variety of probes as it is called the multi-messenger astronomy. The main component in neutron stars is provided by neutron matter, where 1S0 and 3P2 superfluid states of neutrons should be realized at low and high densities, respectively, as the ground state. The gap with spin 2 for neutron parings give many non-trivial structures: spontaneous magnetization along vortex cores [1], half-quantized non-Abelian vortices [2], the existence of soliton solutions by collective excitations along vortices [3], topological superfluidity accompanied with gapless Majorana fermions on surfaces [4], and so on. In the presentation, we will discuss the effect of strong magnetic fields on neutron 3P2 superfluids. We will extend the known formalism for 3P2 superfluids by treating the LS potentials appropriately, and will investigate the phase diagram. We will also discuss possible observations in the multi-messenger astronomy. [1] K. Masuda, M. Nitta, Phys. Rev. C93, 035804 (2016). [2] K. Masuda, M. Nitta, arXiv:1602.07050 [nucl-th]. [3] C. Chatterjee, M. Haberichter, M. Nitta, Phys. Rev. C96, 055807 (2017). [4] T. Mizushima, K. Masuda, M. Nitta, Phys. Rev. B95, 140503(R) (2017). |
Saturday, October 27, 2018 3:15PM - 3:30PM |
MF.00006: Magnetized rotational neutron stars and mass-radius relations Chinatsu Watanabe, Kota Yanase, Naotaka Yoshinaga, Ai Uehara Neutron stars are highly magnetized rotating compact stars. It was reported in 2010 that a neutron star named PSR J1614-2230 making a binary system with a white dwarf has a mass of twice the solar mass (1.97±0.04M☉). In 2013, a neutron star named PSR J0348+0432 with a mass of 2.01±0.04M☉was observed. Such massive neutron stars give strong constraints on the equation of state (EoS) of neutron star matter. In this study, we calculate mass, radius, and eccentricity of magnetized and deformed rotational neutron stars, using a perturbative prescription. As for the EoS a relativistic mean field approach is utilized. We obtain neutron star masses more than 2 M☉ from the mass-radius relation in a strong magnetic field. |
Saturday, October 27, 2018 3:30PM - 3:45PM |
MF.00007: Inhomogeneous Nuclear Matter of Neutron Stars with Strong Magnetic Field Toshiki Maruyama, Cheng-Jun Xia, Nobutoshi Yasutake The central density of neutron star is considered as high as 5-10 times the normal nuclear density. However, we have only limited information on the property of matter at high density. Particularly the equation of state (EOS) is the most important quantity which determines the upper limit of mass of neutron stars. There are several phase transitions of cold nuclear/quark matter relevant to neutron stars. Some of them are of the first order, where mixed phase should appear. The EOS of the mixed phase in general is obtained by solving the Gibbs conditions. The mechanical balance of the surface tension and the Coulomb interaction between two phases should be taken account. As a result, a series of regular geometrical structures called "pasta" emerge to minimize the sum of the surface and the Coulomb energies. The resulting EOS of the mixed phase is found to be between the Maxwell construction and a bulk Gibbs calculation without the surface and the Coulomb energies. On the other hand, some neutron stars have very strong magnetic field. But the effects of magnetic field have not been discussed enough. We investigate the response of inhomogeneous structure against the strong magnetic field such as the change of energy, pressure, chemical ingredient, and density distributions. |
Saturday, October 27, 2018 3:45PM - 4:00PM |
MF.00008: Quark-meson coupling model with the cloudy bag and its application to nuclear and neutron-star properties Tsuyoshi Miyatsu, Koichi Saito Using the volume coupling version of the cloudy bag model, the quark-meson coupling model is extended to study the role of pion and kaon fields in a baryon. The hyperfine interaction due to the gluon exchange as well as that due to the pion and kaon clouds is taken into account, and the baryon mass spectra are well reproduced in vacuum. The extended model then applies to the nuclear matter calculations at the quark-mean field level. In particular, we investigate the effect of the gluon, pion, kaon exchanges on hyperons in matter. In addition, the extension of SU(6) spin-flavor symmetry to SU(3) flavor symmetry is examined in determining the couplings of the vector mesons to the octet baryons, introducing the strange vector mesons. We also present the equation of state for neutron stars, which can support the two-scalar mass neutron stars and the recent neutron-star merger event. |
Saturday, October 27, 2018 4:00PM - 4:15PM |
MF.00009: Variational method with explicit energy functionals for hot nuclear matter with the tensor force Kaoru Shoji, Hajime Togashi, Masatoshi Takano An equation of state for hot nuclear matter has been constructed with the AV6’ two-nucleon potential and the UIX three-nucleon potential by the variational method with explicit energy functionals. For neutron matter and symmetric nuclear matter at zero temperature, energies per nucleon are expressed as explicit functionals of spin-isospin-dependent radial distribution functions and tensor distribution functions. Then the Euler-Lagrange equations for these distribution functions are derived from the energy functionals and are solved numerically. The obtained energies per nucleon are reasonable as compared with those obtained by the Auxiliary Field Diffusion Monte Carlo method. In this presentation, we report on an extension of the above variational method to nuclear matter at finite temperatures following the method by Schmidt and Pandharipande. In this study, the isospin-dependent tensor distribution functions play a crucial role in treating the two-body tensor force and the two-pion-exchange three body force. Furthermore, we will apply the obtained EOS for hot nuclear matter to proto-neutron stars. |
Saturday, October 27, 2018 4:15PM - 4:30PM |
MF.00010: Constraining dark matter with neutron stars Sanjay Reddy I will discuss some recent theoretical developments that allow us to use multi-messenger observations of neutron stars to constrain the properties of candidate dark matter particles with masses less than about a GeV. |
Saturday, October 27, 2018 4:30PM - 4:45PM |
MF.00011: Systematic study of supernova equations of state at sub-nuclear densities with the Thomas-Fermi calculation Hajime Togashi The nuclear equation of state (EOS) plays essential roles in numerical simulations of core-collapse supernovae, black hole formations, and binary neutron star mergers. Recently, we have constructed a new EOS table applicable to such simulations by using the cluster variational method for uniform matter and using the Thomas-Fermi calculation for non-uniform matter. In this study, it is found that the masses of heavy nuclides with our EOS are slightly larger than those with the Shen EOS in neutron-rich nuclear matter because of the smaller value of the density derivative coefficient of the symmetry energy in our EOS. Motivated by this work, we investigate the dependence of the particle compositions in the low-density supernova matter on the empirical saturation values of the uniform EOS in more detail. For this purpose, we systematically construct the EOSs for non-uniform matter with the Thomas-Fermi calculation based on the macroscopic uniform EOS models. In this presentation, we will report on the systematic properties of the non-uniform EOSs at finite temperature and discuss the effects of the saturation parameters included in the uniform EOS on the supernova matter in the low-density inhomogeneous region. |
Saturday, October 27, 2018 4:45PM - 5:00PM |
MF.00012: Higher-order symmetry energy parameters and neutron star properties Akira Ohnishi, Evgeni E. Kolomeitsev, James M. Lattimer, Ingo Tews, Xuhao Wu We discuss the constraints on the higher-order symmetry energy parameters and neutron star radii based on the experimentally constrained range of the symmetry energy parameters (S0, L) and the existence of massive neutron stars. We apply the nuclear matter equation of state (EOS) given in the Fermi momentum expansion with coefficients determined by the saturation and symmetry energy parameters [1]. By using experimentally constrained values of n0, E0, K0, S0, L, and the correlation of Kn and Qn with L found in theoretical model EOSs [1], we find that the 1.4 Msun neutron star radius is found to be in the range R=(10.6-12.2) km as long as we require that the 2 Msun neutron stars are supported. This range is consistent with the gravitational wave observation from GW170817 [2]. We also find a constraint on the third order derivative parameter (Qn) from the existence of 2 Msun neutron stars. [1] I. Tews, J. M. Lattimer, A. Ohnishi, E. E. Kolomeitsev, Astrophys. J. 848 (2017), 105. [2] B. P. Abbott et al. (LIGO Scientific and Virgo Collab.), Phys. Rev. Lett. 119 (2017), 161101. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700