Due to its outstanding characteristics Helium-3 has been indispensable for many decades for the construction of high-efficiency detectors for neutron scattering research into condensed matter. Driven by the escalating supply shortage of Helium-3 the leading neutron facilities worldwide agreed as a matter of priority to collaborate on a programme for the development of possible alternatives to Helium-3 detectors for neutron scattering applications. Focused on the development of large area detectors the collaboration pursues three potential development lines:
Development of large area scintillation detectors
Detectors based on ZnS:6LiF(Ag) or ZnS:10B2O3(Ag) scintillators read out by coded arrays of clear or wavelength shifting fibres and a variety of photomultiplier tubes have been developed in several places. Although some of the required properties may be obtained individually, achieving the desired combination whilst keeping costs reasonable is a problematic challenge for this development.
Gaseous detectors with solid Boron-10 converter
Devices based on this technology are presently used in low efficiency or small area applications only. The deposition of thin Boron-10 layers on very large areas at reasonable cost and the detector design of multilayer arrangements using up to 30 Boron layers to achieve adequate efficiency is a considerable challenge to apply this new technology for neutron scattering applications.
Development of BF3-filled large area neutron detectors
Widely used in the past BF3 was abandoned as detector gas due to its intrinsically lower efficiency and toxicity. Improved multilayer detector designs and the availability of high purity gas nowadays are considered as a potential replacement of 3He detectors on a short term.