ANNI – A pulsed cold neutron beam facility for particle physics at the ESS

Abstract

Pulsed beams have tremendous advantages for precision experiments with cold neutrons. In order to minimise and measure systematic effects, they are used at continuous sources in spite of the related substantial decrease in intensity. At the European Spallation Source ESS these experiments will profit from the pulse structure of the source and its 50 times higher peak brightness compared to the most intense reactor facilities, making novel concepts feasible. Therefore, the cold neutron beam facility for particle physics ANNI was proposed as part of the ESS instrument suite. The proposed design has been re-optimised to take into account the present ESS cold moderator layout. We present design considerations, the optimised instrument parameters and performance, and expected gain factors for several reference experiments.