Ultracold neutron source at the PULSTAR reactor: Engineering design and cryogenic testing

• Published in: Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment Vol. 767; no. C; pp. 169 - 175
• Main Authors: Korobkina, E., Medlin, G., Wehring, B., Hawari, A.I., Huffman, P.R., Young, A.R., Beaumont, B., Palmquist, G.
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 11-12-2014; Elsevier
• Subjects: Assembly; Commissioning; Fundamental particles; Moderation; Nanostructure; Nuclear engineering; Nuclear power generation; Nuclear reactor; Nuclear reactor components; Nuclear reactors; Ortho-para conversion; Raman spectroscopy; Ultracold neutrons; Ortho-para conversion; Ultracold neutrons; Raman spectroscopy; Moderation; Nuclear reactor
• ISSN: 0168-9002; 1872-9576
• DOI: 10.1016/j.nima.2014.08.016

Construction is completed and commissioning is in progress for an ultracold neutron (UCN) source at the PULSTAR reactor on the campus of North Carolina State University. The source utilizes two stages of neutron moderation, one in heavy water at room temperature and the other in solid methane at ~40K, followed by a converter stage, solid deuterium at 5K, that allows a single down scattering of cold neutrons to provide UCN. The UCN source rolls into the thermal column enclosure of the PULSTAR reactor, where neutrons will be delivered from a bare face of the reactor core by streaming through a graphite-lined assembly. The source infrastructure, i.e., graphite-lined assembly, heavy-water system, gas handling system, and helium liquefier cooling system, has been tested and all systems operate as predicted. The research program being considered for the PULSTAR UCN source includes the physics of UCN production, fundamental particle physics, and material surface studies of nanolayers containing hydrogen. In the present paper we report details of the engineering and cryogenic design of the facility as well as results of critical commissioning tests without neutrons.