Thu·Oct 2, 2014Thursday·October 2, 2014

1. 01*

   Offline trapping of ${}^{221}$Fr in a magneto-optical trap from implantation of an ${}^{225}$Ac ion beam

   M. Tandecki · J. Zhang🇺🇸 · S. Aubin · J. A. Behr🇨🇦 · R. Collister · E. Gomez · G. Gwinner🇨🇦 · H. Heggen🇨🇦 · J. Lassen🇨🇦 · L. A. Orozco🇺🇸 · M. R. Pearson🇨🇦 · S. Raeder🇨🇦 · A. Teigelhöfer🇨🇦

   We demonstrate a new technique to prepare an offline source of francium for trapping in a magneto-optical trap. Implanting a radioactive beam of ${}^{225}$Ac, $t_{1/2}=9.920(3)$ days, in a foil, allows use of the decay products, i.e.${}^{221}$Fr, $t_{1/2}=288.0(4)$ s. ${}^{221}$Fr is ejected from the foil by the $\alpha$ decay of ${}^{225}$Ac. This technique is compatible with the online accumulation of a laser-cooled atomic francium sample for a series of planned parity non-conservation measurements at TRIUMF. We obtain a 34% release efficiency for ${}^{221}$Fr from the recoil source based on particle detector measurements. We find that laser cooling operation with the source is $8_{-5}^{+10}$ times less efficient than from a mass-separated ion beam of ${}^{221}$Fr in the current geometry. While the flux of this source is two to three orders of magnitude lower than typical francium beams from ISOL facilities, the source provides a longer-term supply of francium for offline studies.

   ↳ physics.ins-detnucl-exphysics.atom-phJINST(2014)·7 citations
2. 02*

   Underground physics without underground labs: large detectors in solution-mined salt caverns

   Benjamin Monreal🇺🇸

   A number of current physics topics, including long-baseline neutrino physics, proton decay searches, and supernova neutrino searches, hope to someday construct huge (50 kiloton to megaton) particle detectors in shielded, underground sites. With today's practices, this requires the costly excavation and stabilization of large rooms in mines. In this paper, we propose utilizing the caverns created by the solution mining of salt. The challenge is that such caverns must be filled with pressurized fluid and do not admit human access. We sketch some possible methods of installing familiar detector technologies in a salt cavern under these constraints. Some of the detectors discussed are also suitable for deep-sea experiments, discussed briefly. These sketches appear challenging but feasible, and appear to force few major compromises on detector capabilities. This scheme offers avenues for enormous cost savings on future detector megaprojects.

   ↳ physics.ins-dethep-exnucl-ex3 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.