Tue·Feb 6, 2018Tuesday·February 6, 2018

1. 01*

   Electron shakeoff following the \b{eta}+ decay of 19Ne+ and 35Ar+ trapped ions

   X. Fabian🇫🇷 · X. Fléchard🇫🇷 · B. Pons🇫🇷 · E. Liénard🇫🇷 · G. Ban🇫🇷 · M. Breitenfeldt🇧🇪 · C. Couratin🇫🇷 · P. Delahaye🇫🇷 · D. Durand🇫🇷 · P. Finlay🇧🇪 · B. Guillon🇫🇷 · Y. Lemière🇫🇷 and 7 other authors

   The electron shakeoff of 19F and 35Cl atoms resulting from the \b{eta}+ decay of 19Ne+ and 35Ar+ ions has been investigated using a Paul trap coupled to a time of flight recoil-ion spectrometer. The charge-state distributions of the recoiling daughter nuclei were compared to theoretical calculations based on the sudden approximation and accounting for subsequent Auger processes. The excellent agreement obtained for 35Cl is not reproduced in 19F. The shortcoming is attributed to the inaccuracy of the independent particle model employed to calculate the primary shakeoff probabilities in systems with rather low atomic numbers. This calls for more elaborate calculations, including explicitly the electron-electron correlations.

   nucl-exPRA(2018)·20 citations
2. 02*

   Search for the Neutron Decay n$\to$ X+$\gamma$ where X is a dark matter particle

   Z. Tang🇺🇸 · M. Blatnik🇺🇸 · L. J. Broussard🇺🇸 · J. H. Choi🇺🇸 · S. M. Clayton🇺🇸 · C. Cude-Woods🇺🇸 · S. Currie🇺🇸 · D. E. Fellers🇺🇸 · E. M. Fries🇺🇸 · P. Geltenbort🇫🇷 · F. Gonzalez🇺🇸 · T. M . Ito🇺🇸 and 12 other authors

   In a recent paper submitted to Physical Review Letters, Fornal and Grinstein have suggested that the discrepancy between two different methods of neutron lifetime measurements, the beam and bottle methods can be explained by a previously unobserved dark matter decay mode, n$\to$ X+$\gamma$ where X is a dark matter particle. We have performed a search for this decay mode over the allowed range of energies of the monoenergetic gamma ray for X to be a dark matter particle. We exclude the possibility of a sufficiently strong branch to explain the lifetime discrepancy with greater than 4 sigma confidence.

   nucl-exPRL(2018)·101 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.