Pressure Dependence of Wall Relaxation in Polarized $^3$He Gaseous Cells

TL;DR

This study investigates how the longitudinal relaxation time of polarized $^3$He gas in glass cells depends on pressure, revealing a linear relationship and developing a diffusion-based model to explain wall relaxation effects.

Contribution

It introduces a model incorporating diffusion to explain the pressure dependence of wall relaxation in polarized $^3$He cells, challenging previous assumptions of pressure independence.

Findings

Linear pressure dependence of $T_1$ observed at 4.2 K and 295 K.

Diffusion-based model successfully describes the data.

Paramagnetic wall relaxation varies with pressure, contrary to prior beliefs.

Abstract

We have observed a linear pressure dependence of longitudinal relaxation time ($T_1$) at 4.2 K and 295 K in gaseous $^3$He cells made of either bare pyrex glass or Cs/Rb-coated pyrex due to paramagnetic sites in the cell wall. The paramagnetic wall relaxation is previously thought to be independent of $^3$He pressure. We develop a model to interpret the observed wall relaxation by taking into account the diffusion process, and our model gives a good description of the data.