A comparison of two magnetic ultra-cold neutron trapping concepts using a Halbach-octupole array

TL;DR

This paper compares two magnetic trapping configurations for ultra-cold neutrons, evaluating their effectiveness and systematic control for high-precision neutron lifetime experiments.

Contribution

It introduces a new magnetic trap design using a Halbach-octupole array and compares vertical and horizontal setups for systematic effects.

Findings

Vertical and horizontal setups differ in effective volume.

Systematic effects are better controlled in one configuration.

The new trap design enhances precision in neutron lifetime measurements.

Abstract

This paper describes a new magnetic trap for ultra-cold neutrons (UCNs) made from a 1.2 m long Halbach-octupole array of permanent magnets with an inner bore radius of 47 mm combined with an assembly of superconducting end coils and bias field solenoid. The use of the trap in a vertical, magneto-gravitational and a horizontal setup are compared in terms of the effective volume and ability to control key systematic effects that need to be addressed in high precision neutron lifetime measurements.