Mon·Jun 26, 2017Monday·June 26, 2017

1. 01*

   Quantum Monte Carlo calculations of light nuclei with local chiral two- and three-nucleon interactions

   J. E. Lynn🇩🇪 · I. Tews🇺🇸 · J. Carlson🇺🇸 · S. Gandolfi🇺🇸 · A. Gezerlis🇨🇦 · K. E. Schmidt🇺🇸 · A. Schwenk🇩🇪

   Local chiral effective field theory interactions have recently been developed and used in the context of quantum Monte Carlo few- and many-body methods for nuclear physics. In this work, we go over detailed features of local chiral nucleon-nucleon interactions and examine their effect on properties of the deuteron, paying special attention to the perturbativeness of the expansion. We then turn to three-nucleon interactions, focusing on operator ambiguities and their interplay with regulator effects. We then discuss the nuclear Green's function Monte Carlo method, going over both wave-function correlations and approximations for the two- and three-body propagators. Following this, we present a range of results on light nuclei: Binding energies and distribution functions are contrasted and compared, starting from several different microscopic interactions.

   ↳ nucl-thnucl-exPRC(2017)·99 citations
2. 02*

   Upgrade of the ultracold neutron source at the pulsed reactor TRIGA Mainz

   Jan Kahlenberg🇩🇪 · Dieter Ries🇨🇭 · Kim Ulrike Ross · Christian Siemensen🇩🇪 · Marcus Beck · Christopher Geppert🇩🇪 · Werner Heil🇩🇪 · Nicolas Hild🇨🇭 · Jan Karch🇩🇪 · Sergei Karpuk · Fabian Kories · Matthias Kretschmer and 4 other authors

   The performance of the upgraded solid deuterium ultracold neutron source at the pulsed reactor TRIGA Mainz is described. The current configuration stage comprises the installation of a He liquefier to run UCN experiments over long-term periods, the use of stainless steel neutron guides with improved transmission as well as sputter-coated non-magnetic ${}^{58}$NiMo alloy at the inside walls of the thermal bridge and the converter cup. The UCN yield was measured in a `standard' UCN storage bottle (stainless steel) with a volume of 32 litres outside the biological shield at the experimental area yielding UCN densities of 8.5 /cm${}^3$; an increase by a factor of 3.5 compared to the former setup. The measured UCN storage curve is in good agreement with the predictions from a Monte Carlo simulation developed to model the source. The growth and formation of the solid deuterium converter during freeze-out are affected by the ortho/para ratio of the H${}_2$ premoderator.

   ↳ physics.ins-detnucl-exEPJA(2017)·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.