Mon·Jun 7, 2021Monday·June 7, 2021

1. 01*

   Isomers in 203Tl and core excitations built on a five-nucleon-hole structure

   V. Bothe🇩🇪 · S.K. Tandel🇮🇳 · S.G. Wahid🇮🇳 · P.C. Srivastava🇮🇳 · Bharti Bhoy🇮🇳 · P. Chowdhury🇺🇸 · R.V.F. Janssens🇺🇸 · F.G. Kondev🇺🇸 · M.P. Carpenter🇺🇸 · T. Lauritsen🇺🇸 · D. Seweryniak🇺🇸 · S. Zhu🇺🇸

   Isomers with three- and five-nucleon-hole configurations have been established in ${}^{203}$Tl. These include newly identified levels with a three-nucleon structure: {\it I}${}^{\pi }$ = (15/2${}^{-}$) with {\it T}${}_{1/2}$ = 7.9(5) ns, and {\it I}${}^{\pi }$ = (35/2${}^{-}$) with {\it T}${}_{1/2}$ = 4.0(5) ns. In addition, five-quasiparticle states: {\it I}${}^{\pi }$ = (39/2${}^{-}$) with {\it T}${}_{1/2}$ = 1.9(2) ns, and {\it I}${}^{\pi }$ = (49/2${}^{+}$) with {\it T}${}_{1/2}$ = 3.4(4) ns have also been established. The previously determined long-lived decay [{\it T}${}_{1/2}$ = 6.6(3) $\mu$s from this work] is associated with isomerism of the {\it I}${}^{\pi }$ = (29/2${}^{+}$) state. Levels above this long-lived isomer have been identified through a delayed-prompt coincidence measurement. Five-nucleon-hole states with excitation energies {\it E}${}_x$ $\approx$ 7 MeV have been established as well as possible octupole excitations of the ${}^{208}$Pb core built on these levels. The level scheme of ${}^{203}$Tl is extended up to {\it E}${}_x$ $\approx$ 11 MeV with the inclusion of 25 new transitions. Empirical and shell-model calculations have been performed to aid in the description of the observed states which are found to be predominantly of intrinsic character.

   nucl-exPRC(2022)·8 citations
2. 02*

   Precise Measurements of the Decay of Free Neutrons

   Dirk Dubbers🇩🇪 · Bastian Märkisch🇩🇪

   The impact of new and highly precise neutron \b{eta} decay data is reviewed. We focus on recent results from neutron lifetime, \b{eta} asymmetry, and electron-neutrino correlation experiments. From these results, weak interaction parameters are extracted with unprecedented precision, possible also due to progress in effective field theory and lattice QCD. Limits on New Physics beyond the Standard Model derived from neutron decay data are sharper than those derived from high-energy experiments, except for processes involving right-handed neutrinos.

   nucl-exAnn.Rev.Nucl.Part.Sci.(2021)·41 citations
3. 03*

   Systematic study of near yrast band structures in odd-mass ${}^{125-137}$Pr and ${}^{127-139}$Pm isotopes

   S. Jehangir · G.H. Bhat🇮🇳 · N. Rather · J.A. Sheikh · R. Palit🇮🇳

   In the present work, the basis space in the triaxial projected shell model approach is expanded to include three and five quasiparticle configurations for odd-proton systems. This extension allows to investigate the high-spin band structures observed in odd-proton systems up to and including the second band crossing region, and as a first major application of this development, the high-spin properties are investigated for odd-mass ${}^{125-137}$Pr and ${}^{127-139}$Pm isotopes. It is shown that band crossings in the studied isotopes have mixed structures with first crossing dominated by one-proton coupled to two-neutron configuration for the lighter isotopes which then changes to three-proton configuration with increasing neutron number. Further, $\gamma$-bands based on quasiparticle states are also delineated in the present work, and it is predicted that these band structures built on three-quasiparticle configurations become favoured in energy for heavier systems in the high-spin region.

   ↳ nucl-thnucl-exPRC(2021)·16 citations
4. 04*

   Impact of Multiplicity Fluctuations on Entropy Scaling Across System Size

   Patrick Carzon🇺🇸 · Matthew D. Sievert🇺🇸 · Jacquelyn Noronha-Hostler🇺🇸

   The initial state is one of the greatest uncertainties in heavy-ion collisions. A model-agnostic approach is taken in the phenomenological Trento framework which constrains parameters using Bayesian analysis. However, the color-glass condensate (CGC) effective theory predicts initial energy densities that lie outside the recent Bayesian analyses due, in part, to the assumption in Trento of event-by-event multiplicity fluctuations following a $\Gamma$ distribution. We compare the Trento-preferred $\sqrt{T_A{T}_B}$ scaling to CGC-like $T_A{T}_B$ scaling coupled with log-normal fluctuations in $AuAu$ and $dAu$ collisions and find there is a significant impact on the multiplicity distributions and on the eccentricities, which may affect the extraction of viscosity in small systems.

   ↳ nucl-thhep-phnucl-exPRC(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.