CXVI. The beta-gamma angular correlation of 170 Thulium

Abstract

A thin magnetic lens beta-ray spectrometer has been modified to enable the beta-gamma angular correlation of ¹⁷⁰Tm to be measured as a function of beta-ray energy. Assuming that a single matrix element is operative in the low energy beta-ray transition of ¹⁷⁰Tm, the results give a good agreement with the theoretical predictions for the matrix element ∫β σ × r occurring in the first forbidden tensor interaction but appear to rule out the corresponding ∫σ × r of the first forbidden axial vector interaction. It is, however, possible that a suitable mixture of matrix elements might also fit the experimental data.