First Calorimetric Measurement of Electron Capture in 193Pt with a Transition-Edge Sensor.

The neutrino mass can be extracted from a high statistics, high resolution calorimetric spectrum of electron capture in 163Ho. In order to better understand the shape of the calorimetric electron capture spectrum, a second isotope was measured with a close to ideal absorber-source configuration. 193Pt was created by irradiating a 192Pt-enriched platinum foil in a nuclear reactor. This Pt-in-Pt absorber was designed to have a nearly ideal absorber-source configuration. The measured 193Pt calorimetric electron capture spectrum provides an independent check on the corresponding theoretical calculations, which have thus far been compared only for 163Ho. The first experimental and theoretically calculated spectra from this 193Pt-in-Pt absorber are presented and overlaid for preliminary comparison of theory with experiment. [ABSTRACT FROM AUTHOR]