Total cross sections for ultracold neutrons scattered from gases

• Published in: Physical review. C 2017-01, Vol.95 (1), Article 015501
• Main Authors: Seestrom, S. J., Adamek, E. R., Barlow, D., Blatnik, M., Broussard, L. J., Callahan, N. B., Clayton, S. M., Cude-Woods, C., Currie, S., Dees, E. B., Fox, W., Hoffbauer, M., Hickerson, K. P., Holley, A. T., Liu, C.-Y., Makela, M., Medina, J., Morley, D. J., Morris, C. L., Pattie, R. W., Ramsey, J., Roberts, A., Salvat, D. J., Saunders, A., Sharapov, E. I., Sjue, S. K. L., Slaughter, B. A., Walstrom, P. L., Wang, Z., Wexler, J., Womack, T. L., Young, A. R., Vanderwerp, J., Zeck, B. A.
• Format: Article
• Language: English
• Subjects: Atomic and Nuclear Physics; neutron lifetime; NUCLEAR PHYSICS AND RADIATION PHYSICS; ultra cold neutrons
• ISSN: 2469-9985; 2469-9993
• DOI: 10.1103/PhysRevC.95.015501

Here, we have followed up on our previous measurements of upscattering of ultracold neutrons (UCNs) from a series of gases by making measurements of total cross sections on the following gases hydrogen, ethane, methane, isobutene, n-butane, ethylene, water vapor, propane, neopentane, isopropyl alcohol, and 3He. The values of these cross sections are important for estimating the loss rate of trapped neutrons due to residual gas and are relevant to neutron lifetime measurements using UCNs. The effects of the UCN velocity and path-length distributions were accounted for in the analysis using a Monte Carlo transport code. Results are compared to our previous measurements and with the known absorption cross section for 3He scaled to our UCN energy. We find that the total cross sections for the hydrocarbon gases are reasonably described by a function linear in the number of hydrogen atoms in the molecule.