Measurement Of Quasiparticle Transport In Aluminum Films Using Tungsten Transition-Edge Sensors

TL;DR

This paper presents experimental measurements and modeling of quasiparticle transport in aluminum films using tungsten transition-edge sensors, providing insights into phonon sensor physics and quasiparticle dynamics at millikelvin temperatures.

Contribution

It introduces a physical model that accurately reproduces pulse shapes and estimates quasiparticle loss in aluminum films, advancing understanding of TES-based phonon sensors.

Findings

Pulse shapes are well-reproduced by the model.

Quasiparticle loss in Al films is quantitatively estimated.

The overlap region physics explains sensor response.

Abstract

We report new experimental studies to understand the physics of phonon sensors which utilize quasiparticle diffusion in thin aluminum films into tungsten transition-edge-sensors (TESs) operated at 35 mK. We show that basic TES physics and a simple physical model of the overlap region between the W and Al films in our devices enables us to accurately reproduce the experimentally observed pulse shapes from x-rays absorbed in the Al films. We further estimate quasiparticle loss in Al films using a simple diffusion equation approach.