Target and moderator design gives high yields of long wavelength neutrons
The ISIS Second Target Station is a low-power, low-repetition-rate neutron source optimised to maximise the production of long wavelength neutrons. It is required to produce neutrons of two pulse shape varieties.
The first, a wide pulse shape with full width at half-maximum height (FWHM) no bigger than 300 µs and a modest tail, is generated by a coupled moderator; whilst the second is a simple pulse shape de-coupled moderator, with little or no tail, and a width comparable to those of the existing ISIS methane and hydrogen moderators (30–50 µs).
With the physical models for the target and moderators now complete, finalisation of the engineering design for the target/moderator assembly is in progress together with the design of the target services area to handle cooling water and liquid gases.