Data reduction for a calorimetrically measured ^{163}mathrm {Ho} spectrum of the ECHo-1k experiment

Abstract

The electron capture in ^{163}mathrm {Ho} experiment (ECHo) is designed to directly measure the effective electron neutrino mass by analysing the endpoint region of the ^{163}mathrm {Ho} electron capture spectrum. We present a data reduction scheme for the analysis of high statistics data acquired with the first phase of the ECHo experiment, ECHo-1k, to reliably infer the energy of ^{163}mathrm {Ho} events and discard triggered noise or pile-up events. On a first level, the raw data is filtered purely based on the trigger time information of the acquired signals. On a second level, the time profile of each triggered event is analysed to identify the signals corresponding to a single energy deposition in the detector. We demonstrate that events not belonging to this category are discarded with an efficiency above 99.8%, with a minimal loss of ^{163}mathrm {Ho} events of about 0.7%. While the filter using the trigger time information is completely energy independent, a slight energy dependence of the filter based on the time profile is precisely characterised. This data reduction protocol will be important to minimise systematic errors in the analysis of the ^{163}mathrm {Ho} spectrum for the determination of the effective electron neutrino mass.