Fri·Jun 2, 2017Friday·June 2, 2017

1. 01*

   Atomic masses of intermediate-mass neutron-deficient nuclei with relative uncertainty down to 35-ppb via multireflection time-of-flight mass spectrograph

   S. Kimura🇯🇵 · Y. Ito🇯🇵 · D. Kaji🇯🇵 · P. Schury🇯🇵 · M. Wada🇯🇵 · H. Haba🇯🇵 · T. Hashimoto🇰🇷 · Y. Hirayama🇯🇵 · M. MacCormick🇫🇷 · H. Miyatake🇯🇵 · J. Y. Moon🇰🇷 · K. Morimoto🇯🇵 and 9 other authors

   High-precision mass measurements of ${}^{63}$Cu, ${}^{64-66}$Zn, ${}^{65}$Ga, ${}^{65-67}$Ge, ${}^{67}$As, ${}^{78,81}$Br, ${}^{80}$Rb, and ${}^{79}$Sr were performed utilizing a multireflection time-of-flight mass spectrograph combined with the gas-filled recoil ion separator GARIS-II. In the case of ${}^{65}$Ga, a mass uncertainty of 2.1 keV, corresponding to a relative precision of $\delta m/m=3.5\times 10^{-8}$, was obtained and the mass value is in excellent agreement with the 2016 Atomic Mass Evaluation. For ${}^{67}$Ge and ${}^{81}$Br, where masses were previously deduced through indirect measurements, discrepancies with literature values were found. The feasibility of using this device for mass measurements of nuclides more neutron-deficient side, which have significant impact on the $rp$-process pathway, is discussed.

   nucl-exInt.J.Mass Spectrometry(2018)·19 citations
2. 02*

   Precision measurement of the $\beta$-asymmetry in spin-polarized ${}^{37}\mathrm{K}$ decay

   B. Fenker · A. Gorelov · D. Melconian🇺🇸 · J.A. Behr · M. Anholm · D. Ashery · R.S. Behling · I. Cohen · I. Craiciu · G. Gwinner🇨🇦 · J. McNeil · M. Mehlman and 4 other authors

   Using TRIUMF's neutral atom trap, TRINAT, for nuclear $\beta$ decay, we have measured the $\beta$ asymmetry with respect to the initial nuclear spin in ${}^{37}\mathrm{K}$ to be $A_{\beta }=-0.5707(13{)}_{\mathrm{syst}}(13{)}_{\mathrm{stat}}(5{)}_{\mathrm{pol}}$, a 0.3% measurement. This is the best relative accuracy of any $\beta$-asymmetry measurement in a nucleus or the neutron, and is in agreement with the standard model prediction $-0.5706(7)$. We compare constraints on physics beyond the standard model with other $\beta$-decay measurements, and improve the value of $V_{\mathrm{ud}}$ measured in this mirror nucleus by a factor of 4.

   nucl-exPRL(2018)·55 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.