Measurement of the distribution of $^{207}$Bi depositions on calibration sources for SuperNEMO

TL;DR

This paper introduces a novel method using Timepix detectors to precisely measure the distribution of $^{207}$Bi depositions on calibration sources for the SuperNEMO experiment, ensuring accurate energy calibration for double-beta decay studies.

Contribution

The study presents a new technique for accurately assessing the geometry of $^{207}$Bi droplets on calibration sources, improving calibration quality for SuperNEMO.

Findings

49 sources studied, 42 selected for high quality

Precise measurement of droplet geometry achieved

Enhanced calibration accuracy for SuperNEMO

Abstract

The SuperNEMO experiment will search for neutrinoless double-beta decay ($0\nu\beta\beta$), and study the Standard-Model double-beta decay process ($2\nu\beta\beta$). The SuperNEMO technology can measure the energy of each of the electrons produced in a double-beta ($\beta\beta$) decay, and can reconstruct the topology of their individual tracks. The study of the double-beta decay spectrum requires very accurate energy calibration to be carried out periodically. The SuperNEMO Demonstrator Module will be calibrated using 42 calibration sources, each consisting of a droplet of $^{207}$Bi within a frame assembly. The quality of these sources, which depends upon the entire $^{207}$Bi droplet being contained within the frame, is key for correctly calibrating SuperNEMO's energy response. In this paper, we present a novel method for precisely measuring the exact geometry of the deposition of $^{207}$Bi droplets within the frames, using Timepix pixel detectors. We studied 49 different sources and selected 42 high-quality sources with the most central source positioning.