High voltage and electrode system for a cryogenic experiment to search for the neutron electric dipole moment

TL;DR

This paper details the development of a high-voltage electrode system in superfluid helium to enable sensitive neutron electric dipole moment experiments, achieving required electric fields and addressing technical challenges.

Contribution

It presents new technical solutions and experimental demonstrations for high-voltage and electrode systems in cryogenic conditions for neutron EDM searches.

Findings

Achieved electric field of 75 kV/cm in superfluid helium

Developed high-voltage system capable of 635 kV potential

Demonstrated solutions meet heat load and magnetic noise constraints

Abstract

The cryogenic approach to the search for the neutron electric dipole moment--performing the experiment in superfluid liquid helium--holds promise for a substantial increase in sensitivity, potentially enabling a sensitivity level of $10^{-28}$ e-cm. A crucial component in realizing such an experiment is the high voltage and electrode system capable of providing an electric field of 75 kV/cm. This, in turn, requires an electric potential of 635 kV to be applied to the high voltage electrode, while simultaneously satisfying other experimental constraints, such as those on heat load and magnetic noise requirements. This paper describes the outcome of a comprehensive development program addressing these challenges. It outlines the system requirements, discusses new insights into relevant physical phenomena, and details selected technical solutions with their corresponding experimental demonstrations and expected performance. The results collectively demonstrate the successful development of the necessary technology for the high-voltage and electrode system for this approach.