Some General Reflexions on “Long Pulse” Neutron Sources

Abstract

A long pulse spallation neutron source (LPSS) having about 20 times more time average thermal flux than its short pulse counterpart (SPSS) at the same proton beam power and featuring a pronounced time structure not available on cw sources (CWNS) of equal time average flux can in principle host instruments typical for both classes of facilities. While the need for additional choppers introduces some restrictions on inverted time of flight techniques typical for SPSS and while high incident neutron energies are no easier to use on a long pulse than on a continuous neutron source, taking advantage of the pulsed nature of the neutron flux can significantly enhance the performance of direct time of flight instruments and of crystal spectrometers or difiactometers. In this paper some of these options are reviewed in a general manner, and criteria that can be used to optimize the performance enhancement are discussed.