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A small position‐sensitive 3He gas detector has been developed for diffraction studies using short‐wavelength neutrons. It covers 32 × 32 pixels with a 2 mm resolution, which in the present set up corresponds to 0.25°, and the efficiency is 75% at a wavelength of 0.8 Å. The detector has been used for standard data collection, as well as for studies of twinned crystals and measurements involving parasitic reflections. In all cases it has improved the mode and speed of the measurement, with gain factors compared with single detectors which range from more than two in standard measurements to several hundred for the study of details of the Bragg peak(s). The computation time in data analysis and the storage of the data are no major limitations, partly due to the smallness of the data array, and partly due to efficient packing routines.

The key technical aspects of the multiple CCD diffractometer CYCLOPS (Cylindrical CCD Laue Octagonal Photo Scintillator) at the Institut Laue–Langevin are described. Laue patterns subtending 270° horizontally by 92° vertically are read out in less than 3 s to allow nearly real time exploration of reciprocal space and rapid data collection through phase transitions. The first experiments on the same thermal beam as OrientExpress have exceeded expectations and promise exciting new applications for neutron Laue diffraction.

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.

The proposed interstitial location of the hydride ligand in [HRu,(CO),,]-has been established by X-ray and neutron analyses of [Ph,As] [HRu,(C0),,] ALTHOUGH the interstitial nature of hydrogen in binary metal hydrides is well established,l the anion [HRu,(CO),,]-(1) was the first polynuclear carbonyl in which an interstitial hydrogen atom was detected.2 For this compound