UCN Upscattering rates in a molecular deuterium crystal

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.

3 pages, one figure

References in corpus (1)

• Magnetic Trapping of Neutrons

Cited by in corpus (18)

• Electric Dipole Moments of the Atoms, Molecules, Nuclei and Particles
• Demonstration of a solid deuterium source of ultra-cold neutrons
• Measurements of ultracold neutron lifetimes in solid deuterium
• Comparison of ultracold neutron sources for fundamental physics measurements
• Measurement of the neutron $\beta$-asymmetry parameter $A_0$ with ultracold neutrons
• Startup of the High-Intensity Ultracold Neutron Source at the Paul Scherrer Institute
• V2:Performance of the solid deuterium ultra-cold neutron source at the pulsed reactor TRIGA Mainz
• Solid deuterium surface degradation at ultracold neutron sources
• New Understanding of Ultra-Cold Neutron Production in Solid Deuterium
• An Apparatus to Control and Monitor the Para-D2 Concentration in a Solid Deuterium, Superthermal Source of Ultra-cold Neutrons
• Ultracold Neutron Production in a Pulsed Neutron Beam Line
• Scattering cross sections of liquid deuterium for ultracold neutrons: Experimental results and a calculation model
• UCN transport simulation in solid deuterium crystals
• HighNESS Conceptual Design Report: Volume I
• Characterization of ultracold neutron production in thin solid deuterium films at the PSI Ultracold Neutron source
• Thermal up-scattering of very cold and ultra-cold neutrons in solid deuterium
• Cold neutron scattering in imperfect deuterium crystals
• Direct measurement of the scattering cross sections of liquid ortho-deuterium for ultracold neutrons and comparison with model calculations