Dortmund 2021 – scientific programme

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T: Fachverband Teilchenphysik

T 12: Search for New Particles I

T 12.2: Talk

Monday, March 15, 2021, 16:20–16:35, Tl

Optical Design of the ALPS II experiment — •Todd Kozlowski for the ALPS collaboration — University of Florida, Gainesville, USA

Currently under construction at DESY, the Any Light Particle Search (ALPS II) experiment will search for laboratory-generated axions and axion-like particles via photon-axion coupling. The experiment exploits several optical techniques in order to improve sensitivity. Two 122-meter long optical resonators are enclosed within a string of HERA dipole magnets. The first of these resonators is used to amplify the power of a laser field circulating inside the strong magnetic field to generate axions. This Production Cavity (PC) leads to an increase in the axion flux rate which can be measured on the other side of a light-tight barrier. For detection, a second resonator - the Regeneration Cavity (RC) - improves the reconversion rate of axions to photons which are measured with a heterodyne interferometer.

The optical systems must be actively controlled to assure that the frequency of the light circulating inside the PC is simultaneously resonant with the RC, but without allowing any PC light into the RC which would contaminate the detection. Additionally, the experiment requires at least a 95% overlap between the eigenmodes of the PC circulating light and the RC. This talk will discuss these challenges and the designs which will soon be implemented to solve them to allow first data-taking before the end of 2021.