Radiative electron capture in the first forbidden unique decay of 81Kr

TL;DR

This study measures the photon spectrum during electron capture in 81Kr decay, compares it to theoretical models, and finds the best agreement with a recent length gauge-based model.

Contribution

It provides experimental data on radiative electron capture in 81Kr and evaluates theoretical models against observed spectra and intensities.

Findings

Photon spectrum measured for 81Kr decay

Total radiation intensity above 50 keV is 1.47(6) x 10^{-4} per K-capture

Best theoretical agreement with length gauge model

Abstract

The photon spectrum accompanying the orbital K-electron capture in the first forbidden unique decay of 81Kr was measured. The total radiation intensity for the photon energies larger than 50 keV was found to be 1.47(6) x 10^{-4} per K-capture. Both the shape of the spectrum and its intensity relative to the ordinary, non-radiative capture rate, are compared to theoretical predictions. The best agreement is found for the recently developed model which employs the length gauge for the electromagnetic field.