Use of a single-stage, closed-cycle cryorefrigerator for routine measurements at moderately low temperatures on a four-circle neutron diffractometer

Abstract

A single‐stage closed‐cycle helium cryorefrigerator has been installed on a conventional four‐circle neutron diffractometer. The cold head together with a specially designed support and alignment unit are sufficiently compact to enable it to be mounted directly onto the ϕ rotation table within the χ circle in place of the normal goniometer head used for room‐temperature experiments. The device has a temperature range of 50 to 300 K, is extremely simple to use, and has a low operation cost as no cryogenic liquids are consumed. There are additional restrictions on the diffractometer angles but, with care, it is possible to measure at least half the reciprocal sphere.

Deformation density in complex anions. IV. Magnesium thiosulfate hexahydrate, MgS2O3.6H2O

“…Crystal 3.2 x 1.7 x 1.6 mm, to/20 scan, diffractometer D9 at ILL, Grenoble, cryostat described by Allibon, Filhol, Lehmann, Mason & Simms (1981), thermocouple calibrated with a KH2PO 4 crystal (phase transition at 122.8 K), one octant measured up to sin 8/2 = 1.02 A -1, second octant half completed, 4160 reflections, 2771 independent, two standard reflections every 50 reflections, fluctuations up to 5%, data rescaled with respect to standards, background corrections by profile analysis (Lehmann & Larsen, 1974), linear absorption coefficient determined experimentally, transmission range: 0.745 to 0-795, averaging of equivalent reflections: R(/)internal = 0"05, weights assigned to individual reflections according to w(F)= s -2, where s is the larger value of a (F) or 0.03 F.…”

A simple adjustable mount for a two-stage cryorefrigerator on an Eulerian cradle

“…In the present case these are effected as two orthogonal arc motions around a fixed point (Bateman, 1966;Simms, 1981). This principle is depicted in Fig.…”

“…In general they are easy to use and have permitted temperatures of 50-60 K to be obtained in routine operation for one-stage units (Allibon, Filhol, Lehmann, Mason & Simms, 1981) and 10-20 K for two-stage units (Filhol, Reynal, Savariault, Simms & Thomas, 1980;Samson, Goldish & Dick, 1980). The refrigerator consists of a closed-cycle system holding a cortpressor and a valve/expansion unit.…”

Structure of 6-nitro-1,2-benzisothiazol-3(2H)-one 1,1-dioxide sodium salt (6-nitrosaccharin) at 123 K based on neutron diffraction data

“…Diffractometer used: four-circle instrument P32 at the CENG Siloe Reactor, Grenoble. Cryostat: single-stage closed-cycle refrigerator CS 0108-2701/89/071013-03503.00 1003 (Allibon, Filhol, Lehmann, Mason & Simms, 1981). The temperature controller was calibrated using a crystal of KH2PO 4 which has a phase transition at 123 K (Schenk & Weckermann, 1969).…”