The detector calibration system for the CUORE cryogenic bolometer array

TL;DR

The paper presents the design, implementation, and performance evaluation of a novel calibration system for the CUORE cryogenic bolometer array, enabling precise energy calibration in a complex, ultra-low-temperature environment.

Contribution

It introduces a new calibration deployment system specifically designed for the CUORE experiment's cryogenic and radiopure conditions, ensuring accurate detector calibration.

Findings

Successful deployment and removal of calibration sources within the cryostat.

Maintained ultra-low-temperature environment during calibration operations.

Achieved precise energy calibration of the bolometers.

Abstract

The Cryogenic Underground Observatory for Rare Events (CUORE) is a ton-scale cryogenic experiment designed to search for neutrinoless double-beta decay of $^{130}$Te and other rare events. The CUORE detector consists of 988 TeO$_2$ bolometers operated underground at 10 mK in a dilution refrigerator at the Laboratori Nazionali del Gran Sasso. Candidate events are identified through a precise measurement of their energy. The absolute energy response of the detectors is established by the regular calibration of each individual bolometer using gamma sources. The close-packed configuration of the CUORE bolometer array combined with the extensive shielding surrounding the detectors requires the placement of calibration sources within the array itself. The CUORE Detector Calibration System is designed to insert radioactive sources into and remove them from the cryostat while respecting the stringent heat load, radiopurity, and operational requirements of the experiment. This paper describes the design, commissioning, and performance of this novel source calibration deployment system for ultra-low-temperature environments.