Dilution refrigerator for muon spin relaxation experiments

Abstract

The design, construction, and operational characteristics of a continuous 3He–4He dilution refrigerator specifically built for use in muon spin relaxation ( μSR) measurements at LAMPF are described in this paper. The refrigerator is unique in that it makes an angle of 30° with respect to horizontal—a requirement imposed by the previously existing physical constraints of the μSR spectrometer. Additionally, the refrigerator and associated gas handling units are portable so as to facilitate ease of movement into and out of the muon beam. Typical parameters describing refrigerator performance are 60-mK base temperature with 22-μW cooling capacity at 100 mK.