Relaxation of spin polarized 3He by magnetized ferromagnetic contaminants

Abstract

In the first in a series of three papers on wall relaxation of spin polarized 3He we have reported on a breakdown of relaxation times which is observed after exposing the 3He containing glass cells to a strong magnetizing field. In this third paper we give a quantitative analysis of this phenomenon, based on magnetic signal detection by means of SQUIDs, on the pressure dependence of relaxation times in magnetized cells, as well as on Monte Carlo simulations of 3He-relaxation in a macroscopic dipole field. Our analysis allows to identify the contaminants as being aggregates of dust-like Fe3O4 particles (magnetite) with a radius \(R \approx 10~\mu\)m and a remanent magnetic moment of the order of m ≈O(10\(^{-10}~\)A m2). The particles are located at or close to the inner glass surface.