We are delighted to announce that we have been selected to provide the beryllium filter for Bifrost. The ESS (European Spallation Source) spectrometer, named after the burning rainbow bridge from Norse mythology, is scheduled for hot commissioning next summer. The beryllium filter will be installed just before this time. The purpose of this filter is to remove the neutrons with wavelengths over 4 Å and to collimate the scattered neutrons. Both these measures will reduce the background noise of the spectrometer.
Bifrost is one of the eight instruments situated in the long sector of ESS, 162 meters away from the spallation target. The long distance enables a high neutron flux because the entire long pulse of ESS can be used. This unique high flux will facilitate neutron spectroscopy measurements for the fields of quantum materials, super conductivity, and magnetism. These fields are particularly relevant for the development of novel energy materials and IT applications.
When finished, Bifrost will push the boundaries of science by the high neutron flux combined with a high and flexible incident energy resolution. In addition, the spectrometer will provide increased neutron detection efficiency and extreme sample environments. Moreover, future users will be able to do their experiments on as little as one cubic millimetre of material. As the chair of the ESS Scientific and Technical Advisory Panel, Philippe Bourges, puts it: “The instrument surpasses the current capabilities of existing inelastic neutron spectrometers by at least two-digit figures – and this is a rather conservative assessment.”
Beryllium filter design
We are extremely proud to contribute to this ambitious project with our unique knowledge of neutron collimators and years of experience with building custom designs. The design for Bifrost encompasses nine filter units with the focal point of the lamellae centred on the theoretical sample position. Each filter unit consists of beryllium wedges depicted above (in grey) mounted between borated lamellae (in brown). The copper housing facilitates cooling of the wedges to below 95 K. The filter assembly can move around the sample to enable measuring of different scattering angles. The neutrons that are not filtered out, will pass on to the spectrometer tank. Here, crystal analysers will reflect specific energies to the position sensitive detectors (see schematic figure below).
Read more about the Bifrost spectrometer here.
Read more about a similar neutron filter here.
