# Gaseous $^3$He Nuclear Magnetic Resonance Probe for Cryogenic Environments

## TL;DR

This paper introduces a gaseous $^3$He NMR probe capable of high frequency resolution in cryogenic environments, overcoming limitations of traditional probes that freeze and lose resolution at low temperatures.

## Contribution

The paper presents the design and implementation of a gaseous $^3$He NMR probe that functions effectively at cryogenic temperatures, enabling high-resolution measurements where conventional probes fail.

## Key findings

- Achieved frequency resolution better than 0.4 ppb at 4.2 K and 5.3 T
- Successfully shimmed a superconducting solenoid for high magnetic field homogeneity
- Demonstrated stable magnetic field measurements in cryogenic conditions

## Abstract

Normal nuclear magnetic resonance (NMR) probes cannot be used to make high frequency resolution measurements in a cryogenic environment because they lose their frequency resolution when the liquid sample in the probe freezes. A gaseous $^3$He NMR probe, designed and constructed to work naturally in such cryogenic environments, is demonstrated at 4.2 K and 5.3 Tesla to have a frequency resolution better than 0.4 part per billion. As a demonstration of its usefulness, the cryogenic probe is used to shim a superconducting solenoid with a cryogenic interior to produce a magnetic field with a high spatial homogeneity, and to measure the magnetic field stability.