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UCN Upscattering rates in a molecular deuterium crystal

C. -Y. Liu·A. R. Young·S. K. Lamoreaux
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Abstract

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.

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C. -Y. Liu, A. R. Young, S. K. Lamoreaux. 2000-04-07. UCN Upscattering rates in a molecular deuterium crystal. https://doi.org/10.1103/physrevb.62.r3581

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