Sensitive germanium thermistors for cryogenic thermal detector of Tokyo dark matter search programme

TL;DR

This paper reports on the fabrication and sensitivity measurements of n-type and p-type germanium thermistors for cryogenic dark matter detectors, demonstrating their suitability for scaling up bolometer arrays in the Tokyo dark matter search program.

Contribution

It introduces new germanium thermistors fabricated by melt doping and neutron transmutation doping techniques, suitable for large-scale cryogenic dark matter detectors.

Findings

P-type thermistors are sufficiently sensitive for large bolometer arrays.

The thermistors enable scaling up to approximately 1 kg total absorber mass.

Measurements confirm their suitability for cryogenic dark matter detection.

Abstract

Sensitive n-type and p-type germanium thermistors were fabricated by the melt doping technique and by the neutron transmutation doping (NTD) technique, respectively, aiming at a use for the cryogenic thermal detector, or bolometer of Tokyo dark matter search programme. We report on the measurements of the sensitivities of these thermistors. In particular, the p-type thermistors are sensitive enough to scale up our existing prototype LiF bolometer and realize a multiple array of the bolometers with the total absorber mass of about 1\,kg.