Mon·Aug 15, 2022Monday·August 15, 2022

1. 01*

   Constraints on neutron skin thickness and nuclear deformations using relativistic heavy-ion collisions from STAR

   Haojie Xu (for the STAR Collaboration)🇨🇳

   In these proceedings, we present the measurements of neutron skin thickness and nuclear deformation using isobar ${}_{44}^{96}$Ru+${}_{44}^{96}$Ru and ${}_{40}^{96}$Zr+${}_{40}^{96}$Zr collisions at $\sqrt{s_{{}_{\mathrm{NN}}}}=200$ GeV by the STAR detector. The significant deviations from unity of the isobar ratios of elliptic flow $v_2$, triangular flow $v_3$, mean $p_{\mathrm{T}}$ fluctuations $⟨\delta p_{\mathrm{T}}^2⟩/⟨p_{\mathrm{T}}{⟩}^2$, and asymmetric cumulant ${\mathrm{ac}}_2\{3\}$ indicate large differences in their quadrupole and octuple deformations. The significant deviations of the isobar ratios of produced hadron multiplicity $N_{\mathrm{ch}}$, mean transverse momentum $⟨p_{\mathrm{T}}⟩$, and net charge number $\Delta Q$ indicate a halo-type neutron skin for the Zr nucleus, much thicker than for the Ru nucleus, consistent with nuclear structure calculations. We discuss how we extract the neutron skin thickness, the symmetry energy slope parameter, and deformation parameters from data.

   nucl-exnucl-thActa Phys.Polon.Supp.(2023)·15 citations
2. 02*

   Measurements of the ${}^{96}$Zr($\alpha$,n)${}^{99}$Mo cross section for astrophysics and applications

   Gula Hamad🇺🇸 · Kristyn Brandenburg🇲🇽 · Zach Meisel🇺🇸 · Carl R. Brune🇺🇸 · Don E. Carter · David C. Ingram · Yenuel Jones-Alberty🇲🇽 · Thomas N. Massey🇺🇸 · Mansi Saxena · Doug Soltesz🇺🇸 · Shiv K. Subedi🇺🇸 · Alexander V. Voinov🇺🇸

   The reaction ${}^{96}$Zr($\alpha$,n)${}^{99}$Mo plays an important role in $\nu$-driven wind nucleosynthesis in core-collapse supernovae and is a possible avenue for medical isotope production. Cross section measurements were performed using the activation technique at the Edwards Accelerator Laboratory. Results were analyzed along with world data on the ${}^{96}\mathrm{Zr}(\alpha ,n)$ cross section and ${}^{96}\mathrm{Zr}(\alpha ,\alpha )$ differential cross section using large-scale Hauser-Feshbach calculations. We compare our data, previous measurements, and a statistical description of the reaction. We find a larger cross section at low energies compared to prior experimental results, allowing for a larger astrophysical reaction rate. This may impact results of core-collapse supernova $\nu$-driven wind nucleosynthesis calculations, but does not significantly alter prior conclusions about ${}^{99}\mathrm{Mo}$ production for medical physics applications. The results from our large-scale Hauser-Feshbach calculations demonstrate that phenomenological optical potentials may yet be adequate to describe $(\alpha ,n)$ reactions of interest for $\nu$-driven wind nucleosynthesis, albeit with regionally-adjusted model parameters.

   nucl-exPRC(2022)·5 citations
3. 03*

   Photon Production in High-Energy Heavy-Ion Collisions: Thermal Photons and Radiative Recombination

   Hirotsugu Fujii🇯🇵 · Kazunori Itakura🇯🇵 · Katsunori Miyachi🇯🇵 · Chiho Nonaka🇯🇵

   We present a comprehensive analysis of photon production at RHIC and the LHC, proposing radiative hadronization as an additional photon source in high-energy heavy-ion collisions. For thermal photon, we perform relativistic viscous hydrodynamic calculation with event-by-event fluctuations.

   ↳ nucl-thhep-phnucl-exActa Phys.Polon.Supp.(2023)·2 citations
4. 04*

   The Influence of Beta Decay Rates on r-Process Observables

   Kelsey A. Lund · J. Engel🇺🇸 · G.C. McLaughlin🇺🇸 · M.R. Mumpower🇺🇸 · E.M. Ney · R. Surman🇺🇸

   The rapid neutron capture process (r-process) is one of the main mechanisms whereby elements heavier than iron are synthesized, and is entirely responsible for the natural production of the actinides. Kilonova emissions are modeled as being largely powered by the radioactive decay of species synthesized via the r -process. Given that the r -process occurs far from nuclear stability, unmeasured beta decay rates play an essential role in setting the time scale for the r -process. In an effort to better understand the sensitivity of kilonova modeling to different theoretical global beta-decay descriptions, we incorporate these into nucleosynthesis calculations. We compare the results of these calculations and highlight differences in kilonova nuclear energy generation and light curve predictions, as well as final abundances and their implications for nuclear cosmochronometry. We investigate scenarios where differences in beta decay rates are responsible for increased nuclear heating on time scales of days that propagates into a significantly increased average bolometric luminosity between 1-10 days post-merger. We identify key nuclei, both measured and unmeasured, whose decay rates are directly impact nuclear heating generation on timescales responsible for light curve evolution. We also find that uncertainties in beta decay rates significantly impact ages estimates from cosmochronometry.

   ↳ astro-ph.HEastro-ph.SRnucl-exnucl-thApJ(2023)·31 citations

* Reconstructed cohort: no mailing for this day survives in the archive. Papers are grouped by their submission times and arXiv's announcement cut-off, assuming announcement without delay; positions follow identifier order. Validated at ~91% exact-day agreement against the archived era.