Towards TUCAN's Search for the Neutron Electric Dipole Moment

TL;DR

The paper discusses the development of a next-generation ultracold neutron source at TRIUMF aimed at measuring the neutron electric dipole moment with unprecedented sensitivity, involving advanced neutron production and cooling technologies.

Contribution

It introduces a new ultracold neutron source design utilizing a dedicated spallation source, liquid deuterium, and superfluid helium to achieve higher sensitivity in EDM measurements.

Findings

Design of a 20 kW neutron spallation source at TRIUMF

Implementation of liquid deuterium as a cold moderator

Use of superfluid helium for ultracold-neutron conversion

Abstract

The TRIUMF ultracold advanced neutron (TUCAN) collaboration is a transpacific collaboration with the objective to measure the neutron electric dipole moment. We aim for an unprecedented sensitivity of $10^{-27}\,e$cm, an improvement by a factor of 30 over the current upper limit for this elusive quantity. To achieve this goal, we are planning a next-generation source for ultracold neutrons, based on a new, dedicated neutron spallation source at TRIUMF, liquid deuterium as cold moderator, and superfluid helium as ultracold-neutron converter. To operate at the full beam power of 20$\,$kW, a $^3$He fridge will provide a cooling power of 10$\,$W at 0.8$\,$K, cooling the converter to a temperature of 1.1$\,$K.