Mon·Dec 13, 2021Monday·December 13, 2021

1. 01*

   First application of mass measurement with the Rare-RI Ring reveals the solar r-process abundance trend at A=122 and A=123

   H. F. Li🇨🇳 · S. Naimi🇯🇵 · T. M. Sprouse🇺🇸 · M. R. Mumpower🇺🇸 · Y. Abe🇯🇵 · Y. Yamaguchi🇯🇵 · D. Nagae · F. Suzaki · M. Wakasugi · H. Arakawa · W.B. Dou🇯🇵 · D. Hamakawa and 32 other authors

   The Rare-RI Ring (R3) is a recently commissioned cyclotron-like storage ring mass spectrometer dedicated to mass measurements of exotic nuclei far from stability at Radioactive Isotope Beam Factory (RIBF) in RIKEN. The first application of mass measurement using the R3 mass spectrometer at RIBF is reported. Rare isotopes produced at RIBF, ${}^{127}$Sn, ${}^{126}$In, ${}^{125}$Cd, ${}^{124}$Ag, ${}^{123}$Pd, were injected in R3. Masses of ${}^{126}$In, ${}^{125}$Cd, and ${}^{123}$Pd were measured whereby the mass uncertainty of ${}^{123}$Pd was improved. This is the first reported measurement with a new storage ring mass spectrometery technique realized at a heavy-ion cyclotron and employing individual injection of the pre-identified rare nuclei. The latter is essential for the future mass measurements of the rarest isotopes produced at RIBF. The impact of the new ${}^{123}$Pd result on the solar $r$-process abundances in a neutron star merger event is investigated by performing reaction network calculations of 20 trajectories with varying electron fraction $Y_e$. It is found that the neutron capture cross section on ${}^{123}$Pd increases by a factor of 2.2 and $\beta$-delayed neutron emission probability, $P_{1n}$, of ${}^{123}$Rh increases by 14\%. The neutron capture cross section on ${}^{122}$Pd decreases by a factor of 2.6 leading to pileup of material at $A=122$, thus reproducing the trend of the solar $r$-process abundances. The trend of the two-neutron separation energies (S${}_{2n}$) was investigated for the Pd isotopic chain. The new mass measurement with improved uncertainty excludes large changes of the S${}_{2n}$ value at $N=77$. Such large increase of the S${}_{2n}$ values before $N=82$ was proposed as an alternative to the quenching of the $N=82$ shell gap to reproduce $r$-process abundances in the mass region of $A=112-124$.

   nucl-exastro-ph.SRPRL(2022)·34 citations
2. 02*

   ${\beta }^{-}\mathrm{p}$ and ${\beta }^{-}\alpha$ decay of the ${}^{11}$Be neutron halo ground state

   J. Okołowicz🇵🇱 · M. Płoszajczak🇫🇷 · W. Nazarewicz🇺🇸

   Beta-delayed proton emission from the neutron halo ground state of ${}^{11}$Be raised much attention due to the unusually high decay rate. It was argued that this may be due to the existence of a resonance just above the proton decay threshold. In this Letter, we use the lenses of real-energy continuum shell model to describe several observables including the Gamow-Teller rates for the ${\beta }^{-}$-delayed $\alpha$ and proton decays, and argue that, within our model, the large ${\beta }^{-}\mathrm{p}$ branching ratio cannot be reconciled with other data.

   ↳ nucl-thnucl-exJ.Phys.G(2022)·16 citations
3. 03*

   Accessing glue through photoproduction measurements at GlueX

   Peter Pauli (for the GlueX collaboration)🇬🇧

   Photoproduction experiments are a key tool in the investigation of the spectrum of hadronic states and the way gluons contribute to this spectrum. The GlueX experiment, located at Jefferson Lab, features a linearly polarized tagged photon beam and its detector system is optimized to measure a wide range of neutral and charged final states. GlueX offers unique capabilities to study the spectrum of hadrons and is dedicated to the search for hybrid mesons, states with gluonic degrees of freedom. This talk presents first results from our initial campaign of data taking which finished in 2018.

   ↳ hep-exnucl-exRev.Mex.Fis.Suppl.(2022)·5 citations
4. 04*

   Transverse-single-spin asymmetries of charged pions at midrapidity in transversely polarized $p+p$ collisions at $\sqrt{s}=200$ GeV

   U.A. Acharya · C. Aidala · Y. Akiba · M. Alfred · V. Andrieux · N. Apadula · H. Asano · B. Azmoun · V. Babintsev · N.S. Bandara · K.N. Barish · S. Bathe and 300 other authors

   In 2015, the PHENIX collaboration has measured single-spin asymmetries for charged pions in transversely polarized proton-proton collisions at the center of mass energy of $\sqrt{s}=200$ GeV. The pions were detected at central rapidities of $|\eta |<0.35$. The single-spin asymmetries are consistent with zero for each charge individually, as well as consistent with the previously published neutral-pion asymmetries in the same rapidity range. However, they show a slight indication of charge-dependent differences which may suggest a flavor dependence in the underlying mechanisms that create these asymmetries.

   ↳ hep-exnucl-exPRD(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.