Mon·Sep 20, 2021Monday·September 20, 2021

1. 01*

   Evaluation of ${}^{86}$Kr Cross Sections For Use in Fusion Diagnostics

   M. Vorabbi🇺🇸 · G.P.A. Nobre · D.A. Brown🇺🇸 · A.M. Lewis🇺🇸 · E. Rubino🇺🇸 · S. Mughabghab

   The National Ignition Facility at Lawrence Livermore National Laboratory uses ${}^{86}$Kr as a diagnostic tool to measure the neutron flux produced by fusion reactions. As krypton is chemically inert, it can be implanted directly into the fuel capsule, and the reaction products can be measured to determine the flux of fusion neutrons. ${}^{86}$Kr cross sections also provide model constraints for the ${}^{85}$Kr branching point in the s-process and the neutron flux in stars. In this work, experimental data on the neutron production, radiative capture, inelastic scattering, and total cross sections of ${}^{86}$Kr were used in conjunction with the fast region nuclear reaction code EMPIRE and a new resonance-region evaluation to produce a new evaluation of neutron-induced reactions on ${}^{86}$Kr. For the EMPIRE calculations, we fitted the optical model potential up to 12 MeV to simultaneously reproduce the experimental data for the total cross section and the main inelastic gamma transition from the $2^{+}$ state to the $0^{+}$ ground state. For energies above 12 MeV, due to large fluctuations and uncertainties in the total cross section data, we preferred to adopt the Koning-Delaroche global spherical optical model potential. With these models and corrections to the structure of ${}^{86}$Kr, the evaluated cross sections matched the experimental data. The new evaluation has been submitted for incorporation in the next release of the ENDF/B nuclear reaction library.

   nucl-exnucl-th0 citations
2. 02*

   Chronicle of the discovery of the back-bending phenomenon in atomic nuclei: a personal recollection 50 years on

   Hans Ryde

   A chronicle describing the historical context and the development of ideas and experiments leading to the discovery of the back-bending phenomenon in rapidly rotating atomic nuclei some 50 years ago is presented. The moment of inertia of some atomic nuclei increases anomalously at a certain rotational frequency, revealing important clues to our understanding of nuclear structure. I highlight the decisive interactions and contacts between experimentalists and theorists, which created the right environment, allowing for the revelation of an undetected phenomenon in Nature. Finally, I reflect on the key points allowing for the discovery and particularly point to the importance of systematic surveys, which in this case investigated the energy levels in heavy nuclei of a large sample of elements, as well as to the accuracy of the measurements of the ground state levels made at the time.

   ↳ physics.hist-phnucl-exnucl-thEur.Phys.J.H(2021)·0 citations
3. 03*

   Forward doubly-virtual Compton scattering off an unpolarised deuteron in pionless effective field theory

   Vadim Lensky🇩🇪 · Astrid Hiller Blin🇺🇸 · Vladimir Pascalutsa🇩🇪

   We calculate the forward unpolarised doubly-virtual Compton scattering (VVCS) off the deuteron in the framework of pionless effective field theory, up to next-to-next-to-next-to-leading order (N3LO) for the longitudinal and next-to-leading order (NLO) for the transverse amplitude. The charge elastic form factor of the deuteron, obtained from the residue of the longitudinal VVCS amplitude, is used to extract the value of the single unknown two-nucleon one-photon contact coupling that enters the longitudinal amplitude at N3LO. We also study the lowest spin-independent generalised polarisabilities of the deuteron. The calculated unpolarised VVCS amplitude provides a high-precision model-independent input for a future calculation of the two-photon-exchange correction to the Lamb shift of muonic deuterium.

   ↳ nucl-thhep-phnucl-exPRC(2021)·6 citations
4. 04*

   Cranked Skyrme-Hartree-Fock-Bogoliubov approach for a mean-field description of nuclear rotations near the drip line

   Kenichi Yoshida🇯🇵

   To describe the yrast states in weakly bound nuclei, I directly solve the coordinate-space cranked Skyrme-Hartree-Fock-Bogoliubov equation on a three-dimensional lattice with the continuum states discretized in a box. After the numerical demonstration for the ground-state band in a medium-mass nucleus, I apply the newly-developed method to neutron-rich even-$N$ Mg isotopes. I find that the appearance of the significantly low $I^{\pi }=2^{+}$ state in ${}^{40}$Mg is mainly due to the suppression of pairing. The calculation predicts that the $2^{+}$ state in ${}^{42}$Mg appears as high in energy as in ${}^{34\text{-}38}$Mg whereas the triaxial deformation is enhanced in non-zero spin states. The present numerical framework offers a practical approach for investigating the near yrast states systematically and revealing structures unique in drip-line nuclei.

   ↳ nucl-thnucl-exPRC(2022)·4 citations
5. 05*

   The Radioactive Nuclei ${}^{\text{26}}$Al and ${}^{\text{60}}$Fe in the Cosmos and in the Solar System

   Roland Diehl🇩🇪 · Maria Lugaro🇭🇺 · Alexander Heger🇦🇺 · Andre Sieverding🇺🇸 · Xiaodong Tang🇨🇳 · KuoAng Li🇺🇸 · Ertao Li · Carolyn L. Doherty · Martin G.H. Krause · Anton Wallner🇦🇺 · Nikos Prantzos🇫🇷 · Hannah E. Brinkman and 6 other authors

   The cosmic evolution of the chemical elements from the Big Bang to the present time is driven by nuclear fusion reactions inside stars and stellar explosions. A cycle of matter recurrently re-processes metal-enriched stellar ejecta into the next generation of stars. The study of cosmic nucleosynthesis and of this matter cycle requires the understanding of the physics of nuclear reactions, of the conditions at which the nuclear reactions are activated inside the stars and stellar explosions, of the stellar ejection mechanisms through winds and explosions, and of the transport of the ejecta towards the next cycle, from hot plasma to cold, star-forming gas. Due to the long timescales of stellar evolution, and because of the infrequent occurrence of stellar explosions, observational studies are challenging. Due to their radioactive lifetime of million years, the 26Al and 60Fe isotopes are suitable to characterise simultaneously the processes of nuclear fusion reactions and of interstellar transport. We describe and discuss the nuclear reactions involved in the production and destruction of 26Al and 60Fe, the key characteristics of the stellar sites of their nucleosynthesis and their interstellar journey after ejection from the nucleosynthesis sites. We connect the theoretical astrophysical aspects to the variety of astronomical messengers, from stardust and cosmic-ray composition measurements, through observation of gamma rays produced by radioactivity, to material deposited in deep-sea ocean crusts and to the inferred composition of the first solids that have formed in the Solar System. We show that considering measurements of the isotopic ratio of 26Al to 60Fe eliminate some of the unknowns when interpreting astronomical results, and discuss the lessons learned from these two isotopes on cosmic chemical evolution.

   ↳ astro-ph.HEastro-ph.IMastro-ph.SRnucl-ex+1Publ.Astron.Soc.Austral.(2021)·40 citations
6. 06*

   [1]Title: ${\rm Y}$ and ${\eta }_b$ mass shifts in nuclear matter and the ${}^{12}$C nucleus bound states, [2]Title: ${\rm Y}$ and ${\eta }_b$ mass shifts in nuclear matter and the nucleus bound states

   G. N. Zeminiani🇧🇷 · J. J. Cobos-Martínez🇲🇽 · K. Tsushima🇧🇷

   [1]Abstract: This is a contribution for the PANIC 2021 Proceedings based on the articles, Eur. Phys. J. A 57, 259 (2021) and the accompanied article $[$arXiv:2109.08636 $[$hep-ph$]]$ (Hadron 2021 contribution). We have estimated for the first time the mass shifts of the ${\rm Y}$ and ${\eta }_b$ mesons in symmetric nuclear matter by an SU(5) flavor symmetric effective Lagrangian approach, as well as the in-medium mass of $B^{\ast }$ meson by the quark-meson coupling (QMC) model. The attractive potentials for the ${\rm Y}$- and ${\eta }_b$-nuclear matter are obtained, and one can expect for these mesons to form nuclear bound states. We have indeed found such nuclear bound states with ${}^{12}$C nucleus, where the results for the ${}^{12}$C nucleus bound state energies are new, and we report here for the first time. [2]Abstract: We estimate for the first time the mass shifts (scalar potentials) in symmetric nuclear matter of the ${\rm Y}$ and ${\eta }_b$ mesons using an effective Lagrangian approach, as well as the in-medium mass of the $B^{\ast }$ meson by the quark-meson coupling model. The attractive potentials of both ${\rm Y}$ and ${\eta }_b$ are expected to be strong enough for these mesons to be bound to the ${}^4$He nucleus, and we have obtained such nuclear bound state energies.

   ↳ hep-phhep-exnucl-exnucl-thPoS(2022)·6 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.