Speaker
Description
The Any Light Particle Search II (ALPS II) is a light-shining-through-a-wall (LSW) experiment at DESY, Hamburg, attempting to detect axions and axion-like-particles (ALPs), which can comprise dark matter and solve long-standing problems in physics. ALPS II can convert photons into axions/ALPs in the presence of a magnetic field, in an optical cavity. After passing through an opaque, light-tight barrier, these particles can reconvert to photons in another optical cavity, and be detected. The detection requires a sensor capable of observing the extremely low regenerated photon rates of $\mathcal{O}(10^{-5})$ Hz, necessitating a very low dark rate and high detection efficiency. This can be achieved by using a TES, a Transition Edge Sensor, a cryogenic calorimeter exploiting the drastic temperature dependence of a material's electrical resistance in its transition region around 140 mK. To achieve this, the setup is housed in a dilution refrigerator cooling it down to a temperature of $<25$ mK. Being sensitive to low-energy 1064 nm photons also makes the detector susceptible to other particles and backgrounds which can hamper the targeted low dark rate.
We present the setup of the TES detector for ALPS II, its current status, and the analysis of its backgrounds and further improvements in the cryogenic environment to reduce the backgrounds. The viability and outlook of such a detector for the ALPS II experiment will be discussed, including future steps to measure the detection efficiency, etc.
| First author | Rikhav Shah |
|---|---|
| rikhav.shah@desy.de | |
| Collaboration / Activity | ALPS |
