UCN Upscattering rates in a molecular deuterium crystal

Liu, C. -Y.; Young, A. R.; Lamoreaux, S. K.

UCN Upscattering rates in a molecular deuterium crystal

Authors

Liu, C. -Y.

Young, A. R.

Lamoreaux, S. K.

Description

A calculation of ultra-cold neutron (UCN) upscattering rates in molecular deuterium solids has been carried out, taking into account intra-molecular exictations and phonons. The different moelcular species ortho-D2 (with even rotational quantum number J) and para-D2 (with odd J) exhibit significantly different UCN-phonon annihilation cross-sections. Para- to ortho-D2 conversion, furthermore, couples UCN to an energy bath of excited rotational states without mediating phonons. This anomalous upscattering mechanism restricts the UCN lifetime to 4.6 msec in a normal-D2 solid with 33% para content.
3 pages, one figure