Thu·May 21, 2020Thursday·May 21, 2020

1. 01*

   Compressional-mode resonances in the molybdenum isotopes: Emergence of softness in open-shell nuclei near A=90

   K. B. Howard🇺🇸 · U. Garg🇺🇸 · M. Itoh🇯🇵 · H. Akimune🇯🇵 · M. Fujiwara🇯🇵 · T. Furuno · Y. K. Gupta · M. N. Harakeh🇳🇱 · K. Inaba🇯🇵 · Y. Ishibashi · K. Karasudani · T. Kawabata and 11 other authors

   "Why are the tin isotopes soft?" has remained, for the past decade, an open problem in nuclear structure physics: models which reproduce the isoscalar giant monopole resonance (ISGMR) in the "doubly-closed shell" nuclei, ${}^{90}$Zr and ${}^{208}$Pb, overestimate the ISGMR energies of the open-shell tin and cadmium nuclei, by as much as 1 MeV. In an effort to shed some light onto this problem, we present results of detailed studies of the ISGMR in the molybdenum nuclei, with the goal of elucidating where--and how--the softness manifests itself between ${}^{90}$Zr and the cadmium and tin isotopes. The experiment was conducted using the ${}^{94,96,98,100}$Mo($\alpha ,{\alpha }^{\prime }$) reaction at $E_{\alpha }=386$ MeV. A comparison of the results with relativistic, self-consistent Random-Phase Approximation calculations indicates that the ISGMR response begins to show softness in the molybdenum isotopes beginning with $A=92$.

   nucl-exnucl-thPLB(2020)·24 citations
2. 02*

   Measurement of the Background Activities of a 100Mo-enriched powder sample for AMoRE crystal material using a single high purity germanium detector

   Su-yeon Park · Insik Hahn · Woon Gu Kang · Gowoon Kim · Eun Kyung Lee · Douglas S. Leonard · Vladimir Kazalov · Yeong Duk Kim · Moo Hyun Lee · Elena Sala

   The Advanced Molybdenum-based Rare process Experiment (AMoRE) searches for neutrino-less double-beta (0{\nu}\b{eta}\b{eta}) decay of 100Mo in enriched molybdate crystals. The AMoRE crystals must have low levels of radioactive contamination to achieve low background signals with energies near the Q-value of the 100Mo 0{\nu}\b{eta}\b{eta} decay. To produce low-activity crystals, radioactive contaminants in the raw materials used to form the crystals must be controlled and quantified. 100EnrMoO3 powder, which is enriched in the 100Mo isotope, is of particular interest as it is the source of 100Mo in the crystals. A high-purity germanium detector having 100% relative efficiency, named CC1, is being operated in the Yangyang underground laboratory. Using CC1, we collected a gamma spectrum from a 1.6-kg 100EnrMoO3 powder sample enriched to 96.4% in 100Mo. Activities were analyzed for the isotopes 228Ac, 228Th, 226Ra, and 40K. They are long-lived naturally occurring isotopes that can produce background signals in the region of interest for AMoRE. Activities of both 228Ac and 228Th were < 1.0 mBq/kg at 90% confidence level (C.L.). The activity of 226Ra was measured to be 5.1 \pm 0.4 (stat) \pm 2.2 (syst) mBq/kg. The 40K activity was found as < 16.4 mBq/kg at 90% C.L.

   ↳ physics.ins-detastro-ph.IMhep-exnucl-exJ.Korean Phys.Soc.(2020)·4 citations
3. 03*

   Isoscalar monopole and quadrupole modes in Mo isotopes: microscopic analysis

   Gianluca Colo' (1,2)🇮🇹 · Danilo Gambacurta (3,4)🇮🇹 · Wolfgang Kleinig (5)🇷🇺 · Jan Kvasil (6) · Valentin O. Nesterenko (5,7,8)🇷🇺 · Alessandro Pastore (9) ((1) Dipartimento di Fisica, Universita degli Studi di Milano, Italy, (2) INFN, Sezione di Milano, Italy, (3) Extreme Light Infrastructure - Nuclear Physics (ELI-NP), Magurele, Romania, (4) LNS-INFN, Catania, Italy, (5) Laboratory of Theoretical Physics, JINR, Dubna, Russia, (6) Institute of Particle and Nuclear Physics, Charles University, Praha, Czech Republic, (7) State University "Dubna'', Russia, (8) Moscow Institute of Physics and Technology, Dolgoprudny, Russia, (9) Department of Physics, University of York, UK)🇬🇧

   The recent RCNP $(\alpha ,{\alpha }^{\prime })$ data on the Isoscalar Giant Monopole Resonance (ISGMR) and Isoscalar Giant Quadrupole Resonance (ISGQR) in ${}^{92,94,96,98,100}$Mo are analyzed within a fully self-consistent Quasiparticle Random Phase Approximation (QRPA) approach with Skyrme interactions, in which pairing correlations and possible axial deformations are taken into account. The Skyrme sets SkM*, SLy6, SVbas and SkP${}^{\delta }$, that explore a diversity of nuclear matter properties, are used. We discuss the connection between the line shape of the monopole strength ISGMR and the deformation-induced coupling between the ISGMR and the $K=0$ branch of the ISGQR. The ISGMR centroid energy is best described by the force SkP${}^{\delta }$, having a low incompressibility $K_{\infty }$ = 202 MeV. The ISGQR data are better reproduced by SVbas, that has large isoscalar effective mass $m^{\ast }/m$ = 0.9. The need of describing simultaneously the ISGMR and ISGQR data is stressed, with the requirement of suitable values of $K_{\infty }$ and $m^{\ast }/m$. Possible extensions of the QRPA to deal with soft systems are also envisaged.

   ↳ nucl-thnucl-exPLB(2020)·19 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.