2024 Abstract from Ethan

Optical characterization of the InfraBREAD reflector

Student: Ethan Charoenpitaks

Scientists: Andrew Sonnenschein, Stefan Knirck

The InfraBREAD (Broadband Reflector Experiment for Axion Detection) project aims to detect axions by utilizing the Primakoff effect to convert axions into photons and focusing the emitted photons onto a superconducting nanowire single-photon detector (SNSPD) placed at the focal spot of a parabolic reflector-cylindrical reflector assembly. Due to the small size of this SNSPD (~1 mm²), it is necessary to position the SNSPD at the focal spot with a very small tolerance, but manufacturing defects and other issues may cause the focal spot to be significantly off from its simulated position. In this work, we propose a novel mechanism to determine the focal spot of the reflector, using a laser beam to trace the path of the axion. A laser beam is shined through a beam-splitter into the reflector, turned by a lens, reflects off of the cylindrical reflector, and returns through the beam-splitter into a different port. Various internal reflections allow projecting both the original and reflected beams onto two screens. A stage is used to allow moving the characterization assembly. Evaluation of this assembly shows that the assembly is slightly misaligned and the lens spreads out the beam too much to be useful, and we propose solutions to mitigate these issues so that the assembly can be used to accurately characterize the InfraBREAD reflector.