Speaker
Description
Cryogenic transition edge sensors (TESs) are single photon detectors featuring excellent energy resolution below 10% and high quantum efficiency at optical and near-infrared wavelengths. If black-body backgrounds can be suppressed to sufficiently low levels, such detectors would be ideally suited for experiments searching for photon-axion conversion at these wavelengths such as light-shining-through-a-wall (LSW) experiments, axion interferometers, or axion haloscopes. Here, we report on the determination of the system detection efficiency of the TES considered for a potential future run of the Any Light Particle Search II (ALPS II) LSW experiment. With our latest experimental setup, we are able to achieve a system detection efficiency of 86% and milli Hertz background rates. Furthermore, we report on a novel cold optical filter bench that could enables ultra-low backgrounds (below 10^-7 Hz) while maintaining good detection efficiency. The filter bench can be auto-aligned within the cryostat and first results indicate a signal transmission of >~ 60%.
