Bulletin of the American Physical Society
2020 Fall Meeting of the APS Division of Nuclear Physics
Volume 65, Number 12
Thursday–Sunday, October 29–November 1 2020; Time Zone: Central Time, USA
Session MD: Nuclear Astrophysics IV |
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Chair: Wei Jia Ong, LLNL |
Saturday, October 31, 2020 2:00PM - 2:12PM |
MD.00001: Yield measurements of the $^{20}$Ne$(\alpha , \gamma)^{24}$Mg reaction with the St. George recoil mass separator Luis Morales, Alexander Dombos, Manoel Couder, Christopher Seymour, Shane Moylan, Gwenaelle Gilardy, Jerry Hinnefeld, Patricia Huestis, Daniel Robertson, Edward Stech, Michael Skulski, G. P. A. Berg, Michael Wiescher The St. George recoil mass separator at the University of Notre Dame has been used to study the $^{20}$Ne$(\alpha , \gamma)^{24}$Mg reaction. The cross section of $^{20}$Ne$(\alpha , \gamma)^{24}$Mg is critically important in advanced burning stages in massive stars such as carbon, neon and silicon burning. At this stage, three known resonances have been measured for commissioning experiment of St.\ George and the characterization of the focal plane detector. The St. George separates the $^{20}$Ne beam and sends the $^{24}$Mg recoils into a particle identification detection system using the time-of-flight versus residual energy approach. The separator commissioning results will be compared to previous measurements and the detector system characterization will be presented. A path to study $^{20}$Ne$(\alpha , \gamma)^{24}$Mg at lower energy will be discussed. [Preview Abstract] |
Saturday, October 31, 2020 2:12PM - 2:24PM |
MD.00002: Title: Reaction Rate Sensitivity of the Production of $\gamma$-ray Emitting Isotopes in Core-Collapse Supernova Kirby Hermansen, Sean Couch, Luke Roberts, Hendrik Schatz, MacKenzie Warren Radioactive isotopes produced in core-collapse supernovae (CCSNe) provide useful insights into the underlying processes driving the collapse mechanism and the origins of elemental abundances. Here we identify the key nuclear reaction rates to the nucleosynthesis of observable radioactive isotopes in explosive silicon-burning during CCSNe. We evolve temperature-density-time profiles of the innermost $0.45~M_\odot$ ejecta from the core collapse and explosion of a $12~M_\odot$ star. Individually varying 3403 reaction rates by factors of 100, we identify 141 reactions which cause significant differences in the isotopes of interest, namely, $^{43}$K, $^{47}$Ca, $^{44,47}$Sc, $^{44}$Ti, $^{48,51}$Cr, $^{48,49}$V, $^{52,53}$Mn, $^{55,59}$Fe, $^{56,57}$Co, and $^{56,57,59}$Ni. For each of these reactions, we present a novel method to extract the temperature range pertinent to the nucleosynthesis of the relevant isotope; the resulting temperatures lie within the range $T = 0.47$ to $6.15~$GK. Limiting the variations to within $1\sigma$ of standard reaction rate uncertainties further reduces the identified reactions to 48 key rates, which can be used to guide future experimental research. [Preview Abstract] |
Saturday, October 31, 2020 2:24PM - 2:36PM |
MD.00003: Sensitivity of Ti-44 and Ni-56 production in shock-driven nucleosynthesis to nuclear reaction rate variations and the case of 39K(p,g)40Ca. Shiv K. Subedi, Zach Meisel, Grant Merz Recent observational advances have enabled high resolution mapping of Ti-44 in core-collapse supernova (CCSN) remnants. Comparisons between observations and 3D models provide stringent constraints on the CCSN mechanism. However, recent work has identified several uncertain nuclear reaction rates that influence Ti-44 and Ni-56 production in model calculations of shock-driven nucleosynthesis. We evolved 15M, 18M, 22M and 25M stars from ZAMS to CCSN in MESA (Modules for Experiments in Stellar Astrophysics) and investigated previously identified sensitivities of Ti-44 and Ni-56 production in CCSN to varied reaction rates. I will present our final results of this sensitivity study. I will also briefly discuss the current analysis status of direct cross section measurement of 39K(p,g) which is motivated by the sensitivity study. [Preview Abstract] |
Saturday, October 31, 2020 2:36PM - 2:48PM |
MD.00004: Direct measurement of 13N(alpha,p)16O using MUSIC Heshani Jayatissa, Karl Ernst Rehm, Rashi Talwar, Kalle Auranen, Melina Avila, Jie Chen, Clayton Dickerson, Calem Hoffman, Benjamin Kay, Sean Kuvin, Daniel Santiago-Gonzalez, Cheng-Lie Jiang, Richard Pardo, Claudio Ugalde, Jack Winkelbauer, Sergio Almaraz-Calderon The $^{13}$N($\alpha$,p)$^{16}$O reaction has been recently found to have a significant impact in the estimated yields of $^{13}$C during the ingestion of hydrogen into the helium shell of massive stars during the shock propagation of a core-collapse supernovae. The rate of this reaction determines the amount of $^{13}$N that can $\beta$-decay, producing $^{13}$C. The reaction rate of the inverse reaction $^{16}$O(p,$\alpha$)$^{13}$N also plays a role in the creation of $^{12}$C by oxygen burning at high proton abundances via $^{16}$O(p,$\alpha$)$^{13}$N($\gamma$,p)$^{12}$C, which in turn affects the abundances of argon and calcium in type Ia supernovae nucleosynthesis. There are only very few experimental data available for the $^{13}$N($\alpha$,p)$^{16}$O reaction and the rate of this reaction is not well-constrained. A direct measurement of the $^{13}$N($\alpha$,p)$^{16}$O reaction was performed using a 30 MeV secondary beam of $^{13}$N beam from the Argonne In-Flight Radioactive Ion Separator (RAISOR) and the active-target detector MUSIC at Argonne National Laboratory. [Preview Abstract] |
Saturday, October 31, 2020 2:48PM - 3:00PM |
MD.00005: Study of core-collapse supernovae : new experimental constrains on the nuclear physics inputs Simon Giraud The uncertainties on the microphysical ingredients of the core-collapse supernova (CCSN) simulations, e.g. the nuclear masses and the electron capture rates, may conduct to differences in the compositions of the core and in the collapse dynamics. In order to reduce these uncertainties, new high precision mass measurements were performed, via a double Penning trap at the IGISOL facility (Jyv\"{a}skyl\"{a}, Finland) : $^{67}$Fe, $ ^{69gs,69m,70}$Co, $^{74,75}$Ni and $^{76,76m,77,78}$Cu and $^{79m}$Zn. The experimental values of the nuclear gaps for Z=28 and N=50 have been compared with the results predicted by DZ10 and HFB-24 mass models. A moderated impact of the mass model on the composition of the collapsing core was found, while the dynamics of collapse is more sensitive to the electron-capture model. The latter can be better constrained by means of nuclear charge exchange experiments. An upcoming $^{14}$O(d,$^{2}$He)$^{14}$N charge exchange experiment using the Active Target Time Projection Chamber at NSCL should demonstrate a very promising way of constraining the electron capture rates. During this talk I will discuss the effect of the nuclear masses and the electron capture rates in a CCSN simulation as well as their recent experimental constraints. [Preview Abstract] |
Saturday, October 31, 2020 3:00PM - 3:12PM |
MD.00006: Impact of Nuclear Form Factors on Supernova Neutrino Detection in LZ Dev Ashish Khaitan LUX-ZEPLIN (LZ) is a direct detection dark matter experiment, currently under construction $4850~$ft underground at the Sanford Underground Research Facility in Lead, SD, USA. At the core of the LZ design is a dual-phase liquid Xe time projection chamber (TPC) with a $7~$ton active mass. The LZ TPC is optimized to detect low-energy depositions making it sensitive to the neutrino emission from core-collapse supernovae. These neutrinos, with O($10~$MeV) kinetic energy, can interact via coherent elastic neutrino-nucleus scattering (CE$\nu$NS) depositing O($1~$keV) in LZ. This presentation gives an overview of the LZ TPC, presents different CEvNS nuclear form factors and discusses the impact they have on LZ's sensitivities to these signals. [Preview Abstract] |
Saturday, October 31, 2020 3:12PM - 3:24PM |
MD.00007: Neutrino self-interaction and MSW effects in supernovae and the $\nu$-process Grant Mathews, Luca Boccioli, Heamin Ko, Myung-ki Cheoun, Eunja Ha, Motohiko Kusakabe, Takehito Hayakawa, Hirokazu Sasaki, Toshitaka Kajino, Masa-Ako Hashimoto, Masaomi Ono We consider the modification of the neutrino spectrum and luminosity from core-collapse supernovae both by the neutrino self-interaction near the neutrinosphere and the Mikheyev-Smirnov-Wolfenstein effect in the outer layers. We show the effects of these interactions on the gain radius in the delayed neutrino heating of the supernova. We also consider the impact of these modification to the neutrino spectrum on the $\nu$-process nucleosynthesis in the outer parts of the star. We find that the abundances of $^7$Li and the heavy isotopes $^{92}$Nb, $^{98}$Tc and $^{138}$La are reduced by a factor of $\sim 2$ by the $\nu$-self-interaction. In contrast, $^{11}$B is relatively insensitive. We also find that the abundance ratio of heavy to light nuclei, $^{138}$La/$^{11}$B, is a possible new probe of the neutrino mass hierarchy, and that the normal mass hierarchy is slightly favored by solar meteoritic abundances. [Preview Abstract] |
Saturday, October 31, 2020 3:24PM - 3:36PM |
MD.00008: Spin and density response functions for hot and dense nuclear matter from chiral nuclear forces Eunkyoung Shin, Jeremy Holt, Ermal Rrapaj, Sanjay Reddy The response functions and associated dynamical structure factors of nuclear matter affect neutrino propagation in core-collapse supernovae and neutron star mergers. In this talk we will discuss new calculations of the spin and density response functions of beta equilibrium matter under a wide range of ambient conditions starting from realistic chiral nuclear forces. We include both mean field and vertex corrections at first order in many-body perturbation theory. The former have already been shown to significantly affect neutrino charged-current reactions in the neutrinosphere, and in the present work we highlight the role of vertex corrections that enter at the same order in perturbation theory. Theoretical uncertainties are estimated by varying the order in the chiral expansion and the high-momentum cutoff scale in the effective field theory expansion of the nuclear force. We expect the results of this study to provide theoretical guidance for neutrino reaction rates used in numerical simulations of supernovae and neutron star mergers. [Preview Abstract] |
Saturday, October 31, 2020 3:36PM - 3:48PM |
MD.00009: Black Dwarf Supernova in the Far Future Matt Caplan In the far future the universe will be populated by sparse degenerate remnants, mostly white dwarfs (WDs), though their ultimate fate is an open question. These WDs will cool and freeze solid into 'black' dwarfs while pycnonuclear fusion will slowly process their composition to iron-56. However, due to the declining electron fraction the Chandrasekhar limit of these stars will decrease down to about $\sim 1.2 M_\odot$, so WDs with masses between 1.2 and 1.4 $M_\odot$ will collapse in the far future due to the slow accumulation of iron-56 in their cores. If proton decay does not occur then this is the ultimate fate of about one percent of all stars in the observable universe. We present calculations of the internal structure of black dwarfs with iron cores as a model for progenitors. From fusion rates we estimate their lifetime and thus delay time to be $10^{1100}$ years. We speculate that high mass supernovae resemble accretion induced collapse of O/Ne/Mg WDs while later low mass transients will be similar to stripped-envelope supernova, and may be the last interesting astrophysical transients to occur prior to heat death. Though there are few observational consequences, this result may be of popular interest and motivates the study of far future WD evolution. [Preview Abstract] |
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