Characterization, 1064 nm photon signals and background events of a tungsten TES detector for the ALPS experiment

TL;DR

This paper characterizes a tungsten TES detector at 1064 nm for the ALPS experiment, demonstrating effective background suppression and photon detection efficiency, crucial for searching for ultra-light particles.

Contribution

First detailed characterization and background analysis of a tungsten TES detector tailored for the ALPS experiment's photon detection needs.

Findings

Achieved ~10^{-3} background suppression with 50% photon efficiency.

Overall detector efficiency of 23% with a dark count rate of 8.6×10^{-3} s^{-1}.

Pile-up thermal photon events are the main background source.

Abstract

The high efficiency, low-background, and single-photon detection with transition-edge sensors (TES) is making this type of detector attractive in widely different types of application. In this paper, we present first characterizations of a TES to be used in the Any Light Particle Search (ALPS) experiment searching for new fundamental ultra-light particles. Firstly, we describe the setup and the main components of the ALPS TES detector (TES, millikelvin-cryostat and SQUID read-out) and their performances. Secondly, we explain a dedicated analysis method for single-photon spectroscopy and rejection of non-photon background. Finally, we report on results from extensive background measurements. Considering an event-selection, optimized for a wavelength of $1064~{\rm nm}$, we achieved a background suppression of $\sim 10^{-3}$ with a $\sim 50~\%$ efficiency for photons passing the selection. The resulting overall efficiency was $23~\%$ with a dark count rate of $8.6 \cdot 10^{-3}~{\rm s}^{-1}$. We observed that pile-up events of thermal photons are the main background component.