We have investigated experimentally the pressure dependence of the production of ultracold neutrons (UCN) in superfluid helium in the range from saturated vapor pressure to 20bar. A neutron velocity selector allowed the separation of underlying single-phonon and multiphonon pro- cesses by varying the incident cold neutron (CN) wavelength in the range from 3.5 to 10{\AA}. The predicted pressure dependence of UCN production derived from inelastic neutron scattering data was confirmed for the single-phonon excitation. For multiphonon based UCN production we found no significant dependence on pressure whereas calculations from inelastic neutron scattering data predict an increase of 43(6)% at 20bar relative to saturated vapor pressure. From our data we conclude that applying pressure to superfluid helium does not increase the overall UCN production rate at a typical CN guide.
@article{arxiv.1506.07785,
title = {Experimental study of ultracold neutron production in pressurized superfluid helium},
author = {P. Schmidt-Wellenburg and J. Bossy and E. Farhi and M. Fertl and K. K. H. Leung and A. Rahli and T. Soldner and O. Zimmer},
journal= {arXiv preprint arXiv:1506.07785},
year = {2015}
}
Comments
18 pages, 8 figures Version accepted for publication in PRC