Pulsed neutron beam control using a magnetic multiplet lens

As a magnetic neutron lens based on a sextupole magnet to focus neutrons has chromatic aberration, it has been proposed that the chromatic aberration can be compensated in the pulsed neutron beam focusing by combining the focusing and defocusing functions of the multiplet magnetic lens system synchronously with time-of-flight (TOF) of neutrons. In this study, we performed numerical simulations on the multiplet magnetic lens system to investigate how a pulsed neutron beam can be controlled on the basis of the TOF method. It was then confirmed that the chromatic aberration can be compensated and the focal condition can be maintained over a certain λ-range by utilizing plural magnetic lenses in series and choosing the focusing and defocusing function of each magnetic lens synchronously with TOF of neutrons.