Measurement of the 171Tm beta spectrum

TL;DR

This paper reports a precise measurement of the beta spectrum end-point energy of 171Tm decay using an improved spectrometer, confirming previous results and validating theoretical shape calculations with high accuracy.

Contribution

It presents an improved spectrometer setup and a new measurement of the 171Tm beta spectrum end-point energy, aligning with prior data and supporting theoretical models.

Findings

Measured end-point energy: 97.60(38) keV

Good agreement between experimental spectrum and xi-approximation theory

Spectrometer improvements reduced low energy threshold to 34 keV

Abstract

The beta spectrum of the main transition of the beta-decay of 171Tm was measured using a double focalizing spectrometer. The instrument was lately improved in order to reduce its low energy threshold to 34 keV. We used the spectrometer to measure the beta spectrum end-point energy of the main transition of 171Tm decay using the Kurie plot formalism. We report a new value of 97.60(38) keV, which is in agreement with previous measurements. In addition, the spectrum shape was compared with the xi-approximation calculation where the shape factor is equal to 1 and good agreement was found between the theory and the measurement at the 1% level.