Mon·Jun 21, 2021Monday·June 21, 2021

1. 01*

   Cross-sections of photonuclear reactions on ${}^{nat}$Mo targets at end-point bremsstrahlung energy up to $E_{\gamma max}$ = 100 MeV

   A.N. Vodin🇺🇦 · O.S. Deiev🇺🇦 · I.S. Timchenko🇺🇦 · S.M. Olejnik🇺🇦 · V.A. Kushnir🇺🇦 · V.V. Mytrochenko🇺🇦 · S.O. Perezhogin · V.O. Bocharov

   Experiments to determine the yields and bremsstrahlung flux-averaged cross-sections <$\sigma (E_{\gamma max})$> of photonuclear reactions on the natural Mo targets were performed on the beam from the NSC KIPT electron linear accelerator LUE-40 with the use of the $\gamma$-activation technique. The bremsstrahlung end-point energies were in the range $E_{\gamma max}$ = 35...80 MeV. The bremsstrahlung quantum flux was calculated with the program GEANT4.9.2 and, in addition, was monitored using the ${}^{100}$Mo$(\gamma ,n{)}^{99}$Mo reaction. Calculations of the yields and average cross-sections <$\sigma (E_{\gamma max})$> for photonuclear reactions on stable Mo isotopes were computed using the $\sigma (E)$ cross-sections from the TALYS1.95 code (for the level density model LD1). A comparison of experimental and calculated cross-sections <$\sigma (E_{\gamma max})$> for reactions ${}^{92}$Mo$(\gamma ,2n{)}^{90}$Mo and ${}^{92}$Mo$(\gamma ,pn{)}^{90}$Nb was performed.

   nucl-exProb.Atomic Sci.Technol.(2021)·3 citations
2. 02*

   Decoding the Density Dependence of the Nuclear Symmetry Energy

   W. G. Lynch🇺🇸 · M. B. Tsang🇺🇸

   The large imbalance in the neutron and proton densities in very neutron rich systems increases the nuclear symmetry energy so that it governs many aspects of neutron stars and their mergers. Extracting the density dependence of the symmetry energy therefore constitutes an important scientific objective. Many analyses have been limited to extracting values for the symmetry energy, $S_0$, and its ``derivative'', $L$, at saturation density ${\rho }_0\approx 2.6\times 10^{14}g/c{\mathrm{m}}^3$ $\approx 0.16nucleons/f{\mathrm{m}}^3$, resulting in constraints that appear contradictory. We show that most experimental observables actually probe the symmetry energy at densities far from ${\rho }_0$, making the extracted values of $S_0$ or $L$ imprecise. By focusing on the densities these observables actually probe, we obtain a detailed picture of the density dependence of the symmetry energy from $0.25{\rho }_0$ to $1.5{\rho }_0$. From this experimentally derived density functional, we extract $L_{01}=53.1\pm 6.1MeV$ at $\rho \approx 0.10\mathrm{f}{\mathrm{m}}^{-3}$, a neutron skin thickness for ${}^{208}Pb$ of $R_{np}=$ $0.23\pm 0.04$ fm, a symmetry pressure at saturation density of $P_0=3.2\pm 1.2MeV/f{m}^3$ and suggests a radius for a 1.4 solar mass neutron star of $13.1\pm 0.6$ km.

   ↳ nucl-thastro-ph.HEastro-ph.SRnucl-exPLB(2022)·81 citations
3. 03*

   Shell model analysis of the $B(E2,2^{+}\to 0^{+})$'s in the A=70 T=1 triplet

   S. M. Lenzi🇮🇹 · A. Poves🇪🇸 · A. O. Macchiavelli🇺🇸

   he $B(E2,2^{+}\to 0^{+})$ transition strengths of the T=1 isobaric triplet ${}^{70}$Kr, ${}^{70}$Br, ${}^{70}$Se, recently measured at RIKEN/RIBF, are discussed in terms of state of the art large scale shell model calculations using the JUN45 and JUN45+LNPS plus Coulomb interactions. In this letter we argue that, depending on the effective charges used, the calculations are either in line with the experimental data within statistical uncertainties, or the anomaly happens in ${}^{70}$Br, rather than ${}^{70}$Kr. In the latter case, we suggest that it can be due to the presence of a hitherto undetected 1${}^{+}$ T=0 state below the yrast 2${}^{+}$ T=1 state. Our results do not support a shape change of ${}^{70}$Kr with respect to the other members of the isobaric multiplet.

   ↳ nucl-thnucl-exPRC(2021)·13 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.