Estimated performance of the TRIUMF ultracold neutron source and electric dipole moment apparatus

Abstract

Searches for the permanent electric dipole moment of the neutron (nEDM) provide strong constraints on theories beyond the Standard Model of particle physics. The TUCAN collaboration is constructing a source for ultra-cold neutrons (UCN) and an apparatus to search for the nEDM at TRIUMF, Vancouver, Canada. In this work, we estimate that the spallation-driven UCN source based on a superfluid helium converter will provide (1.38 ± 0.02) 107 polarized UCN at a density of 217 ± 3 UCN/cm3 to a room-temperature EDM experiment per fill. With (1.43 ± 0.02) 106 neutrons detected after the Ramsey cycle, the statistical sensitivity for an nEDM search per storage cycle will be (1.94 ± 0.06) × 10−25 ecm (1σ). The goal sensitivity of 10−27 ecm (1σ) can be reached within 281 ± 16 measurement days.