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

TL;DR

This paper estimates the performance of the TRIUMF ultracold neutron source and nEDM apparatus, predicting high UCN densities and sensitivities that could significantly advance neutron electric dipole moment searches within a feasible timeframe.

Contribution

It provides the first detailed performance estimates for the TRIUMF UCN source and nEDM experiment, including neutron yields, densities, and sensitivity projections.

Findings

UCN source yields approximately 1.38×10^7 polarized UCN per fill

Predicted statistical sensitivity of 1.94×10^−25 e·cm per cycle

Potential to reach 10^−27 e·cm sensitivity within 280 days

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 ultracold 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 $(1.38\pm0.02) \times 10^7$ polarized UCN at a density of $217\pm3$~UCN/cm$^3$ to a room-temperature EDM experiment per fill. With $(1.51\pm0.02) \times 10^6$ neutrons detected after the Ramsey cycle, the statistical sensitivity for an nEDM search per storage cycle will be $(1.94\pm0.06) \times 10^{-25}\,e$cm (1$\sigma$). The goal sensitivity of $10^{-27}\,e$cm (1$\sigma$) can be reached within $280\pm16$ measurement days.