Bulletin of the American Physical Society
87th annual meeting of the Southeastern Section of the APS
Volume 65, Number 19
Thursday–Friday, November 5–6, 2020; Virtual
Session F04: Low Energy Nuclear Physics - Cosmology and Astrophysics |
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Chair: Miguel Madurga, University of TN |
Friday, November 6, 2020 11:00AM - 11:12AM |
F04.00001: Beta-Decay of 29F: The Southern Shore of The Island of Inversion Jesse Farr The island of inversion in regards to nuclear physics refers to exotic neutron-rich nuclei that do not follow a standard configuration in the nuclear shell model. To explore this region, the 29F experiment will run in October 2020 at NSCL in Michigan State University. This experiment studies an isotope of fluorine, 29F, in a fragmentation nuclear reaction by implanting it in a crystal detector to measure its decay. By analyzing the decay of this neutron-rich isotope, it will lead to a better understanding of its decay strength, ground state wave function, and the internal structure of 29F and other exotic nuclei near the island of inversion. The VANDLE array alongside a YSO scintillator and three clover detectors will analyze the ions for each individual event to map the decay. The clovers are fitted with thin beta-veto (Betos) plastics in order to maximize efficiency; we determined 1 mm offered the best compromise between high beta response and small gamma background. In this presentation we will show the simulations and evaluation data used to define the beta gamma response. [Preview Abstract] |
Friday, November 6, 2020 11:12AM - 11:24AM |
F04.00002: Covariant density functional theory: an estimation of systematic uncertainties Ahmad Taninah, S. E. Agbemava, A. V. Afanasjev The systematic investigation of the ground state and fission properties of even-even actinides and superheavy nuclei with $Z=90-120$ from the two-proton up to two-neutron drip lines with proper assessment of systematic theoretical uncertainties has been performed for the first time in the framework of covariant density functional theory (CDFT). Four state-of-the-art globally tested covariant energy density functionals (CEDFs), namely, DD-PC1, DD-ME2, NL3* and PC-PK1, representing the major classes of the CDFT models are employed in the present study. Ground state deformations, binding energies, two neutron separation energies, $\alpha$-decay $Q_{\alpha}$ values and half-lives and the heights of fission barriers have been calculated for all these nuclei. Theoretical uncertainties in these physical observables and their evolution as a function of proton and neutron numbers have been quantified and their major sources have been identified. Spherical shell closures at $Z=120$, $N=184$ and $N=258$ and the structure of the single-particle (especially, high-$j$) states in their vicinities as well as nuclear matter properties of employed CEDFs are two major factors contributing into theoretical uncertainties. [Preview Abstract] |
Friday, November 6, 2020 11:24AM - 11:36AM |
F04.00003: Global Performance and Optimization of Separable Pairing in Covariant Density Functional Theory Saja Teeti, Anatoli Afanasjev Over the recent years separable pairing interaction [1] has found a widespread use in covariant density functional theory (CDFT) as an alternative to the pairing interaction based on the finite range Gogny force [2]. Both types of pairing allow to eliminate the uncertainties connected with the definition of the size of pairing window, but the former one is less numerically time-consuming. For the first time we carried out the global analysis of the performance of separable pairing and its optimization as a function of mass, proton and neutron numbers. The analysis is based on the comparison of calculated $\Delta_{uv}$ pairing gaps in even-even nuclei [which according to Ref. [4] represents the best measure of pairing correlations] with experimental $\Delta^{(5)}$ pairing indicators. The impact of time-odd mean fields on pairing indicators is taken into account. [1] Y. Tian, Z. Y. Ma, and P. Ring, Phys. Lett. B 676, 44 (2009). [2] D. Vretenar, A.V. Afanasjev, G.A. Lalazissis and P. Ring, Phys. Rep. 409 (2005) 101. [3] S. Teeti and A. V. Afanasjev, in preparation. [4] S. E. Agbemava, A. V. Afanasjev, D. Ray, and P. Ring, Phys. Rev. C 89, 054320 (2014). [Preview Abstract] |
Friday, November 6, 2020 11:36AM - 11:48AM |
F04.00004: Cosmic Rays and Galactic Motion Tori Snyder As the solar system travels it oscillates across the dense galactic plane with a periodicity much smaller than its galactic orbital period. Assuming current conditions, the disk crossing period is estimated between 30 and 42 Ma. This would mean that galactic cosmic ray fluxes, and other observations on our planet, might also be expected to vary on a similar cycle, with fluxes being much higher during intervals when our solar system is close to the galactic plane. On our planet, living and dead creatures connect with cosmic rays. This is because several radioactive isotopes are produced in the upper atmosphere when cosmic rays collide with atmospheric molecules at high speed. These isotopes are known as cosmogenic isotopes. The production rate of the cosmogenic isotopes depends on the strength of the cosmic radiation, which again varies with the strength of the geomagnetic field and solar activity. Therefore, the abundance of cosmogenic isotopes in fossils may give a glimpse into the radiation history of our planet. A connection between calcitic fossil shells is claimed to yield a 32 Ma oscillation which would be consistent with the galactic oscillation idea$^{\mathrm{.}}$ In this project we propose to examine several datasets: first, the Phanerozoic dataset of almost 25,000 calcitic fossils with their radiogenic isotopes; second, the solar cycle dataset from the space age on planet Earth. Using these data sets we hope to be able to compare the data and learn about the effect that cosmic ray fluxes have on earth and the solar system. [Preview Abstract] |
Friday, November 6, 2020 11:48AM - 12:00PM |
F04.00005: Update on the GRB-Triggered Search for Gravitational Waves in Advanced LIGO and Advanced Virgo's Third Observing Run Ryan Fisher The combined observation of GRB 170817A and GW170817 marked the first multimessenger success of gravitational wave astronomy. Although no further coincident observations were found in the second observing run of Advanced LIGO and Advanced Virgo, we continued this search in the third observing run, which concluded on Mar 27, 2020. This talk will present the current status of the effort to conduct template-based searches for gravitational waves in Advanced LIGO and Advanced Virgo data, triggered by gamma-ray bursts disseminated by the Gamma-ray Coordinates Network (GCN). This talk will discuss both the high-latency, full analysis and efforts that were made to bring a lightweight, rapid-followup analysis into production. [Preview Abstract] |
Friday, November 6, 2020 12:00PM - 12:12PM |
F04.00006: Angular Momentum in Asymptotically Flat Spacetimes Arwa Elhashash, David Nichols The symmetries of asymptotically flat spacetimes in general relativity can be described by Bondi-Metzner-Sachs group and its proposed extensions. Each symmetry is associated with a conserved charge that characterizes the spacetime. These charges include energy-momentum, relativistic angular momentum, supermomentum and super-angular momentum. We focus on the angular momentum. There have been several formalisms that lead to different definitions of angular momentum. These definitions give inequivalent values of the angular momentum for the same spacetime. They can be summarized in a two-parameter family dependent expression. Requiring the angular momentum to vanish in flat spacetime restricts the two parameters to be equal. However there is no obvious physical or mathematical reason to fix this one remaining free parameter to a particular value. We further examine if one allowed this one parameter to be free how much of an effect it would have on the super-angular momentum for non-spinning binary black hole mergers. We use an inspiral-merger-ringdown waveform and estimate that effect to cause 1 part in $10^5$ change in the super-angular momentum for equal mass binary and gets smaller with increasing mass ratios. [Preview Abstract] |
Friday, November 6, 2020 12:12PM - 12:24PM |
F04.00007: Identification of Key Isotopes in Kilonova Heating Kelsey Lund, Yonglin Zhu, Jennifer Barnes, Trevor Sprouse, Nicole Vassh, Gail McLaughlin, Matthew Mumpower, Rebecca Surman The rapid neutron capture process (r-process) is one of the main mechanisms whereby elements heavier than iron are synthesized, and is responsible for the creation of the heaviest stable actinides. Observations of the gravitational wave event GW170817, and its optical counterpart, AT2017gfo, support neutron star mergers as an r-process production site. Accurately and reliably modelling yields and observational signatures from these sites requires inputs from nuclear physics, which introduce potentially large uncertainties. We use nucleosynthesis modeling to evaluate the effect of varying these inputs, including different nuclear mass models, fission decay rates, and daughter product distributions in lanthanide and actinide production. I show that applying different nuclear physics inputs generates discrepancies in abundances of key isotopes which contribute significantly to the overall nuclear energy generation in the merger event, which is a necessary component of kilonova light curve modeling. [Preview Abstract] |
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