Current status and future directions of position sensitive neutron detectors at ISIS

Position sensitive detectors at the ISIS facility largely comprise of a mixture of 3He proportional counters and fibre-coded scintillation detectors based on ZnS/6LiF. The latest developments of these devices at ISIS will be discussed with reference to three ISIS instruments, MERLIN, GEM and ENGIN-X. is the new chopper spectrometer now being developed at ISIS and features a large 2D detector array covering more than 20 m2 with a requirement in position resolution of 25×25 mm2. Resistive wire detectors are proposed for this detector, but to minimise gaps in the solid angle, detectors with active lengths of 2.9 m are being proposed. Initial results from prototype detectors will be presented. GEM is a general materials diffractometer now nearing completion and ENGIN-X is the engineering instrument, which became operational in November 2002. Detectors for both these instruments use linear arrays of fibre optic-encoded ZnS/6Li scintillator, with position resolutions of 5 and 3 mm, respectively. as now started on the construction of the ISIS second target station, TS-2. This facility will be tailored to the production of lower-energy neutrons compared with target station 1, with applications predominantly in soft condensed matter, bio-molecular sciences and advanced materials. The challenges this presents for future neutron detector development at ISIS will be reviewed together with some potential lines of detector development.