ALPS II Science Runs and Upgrades

Astronomical measurements indicate that nearly 85% of the matter in the Universe is yet unknown particles and determining the nature of this “dark matter” is the basis for one of the most extensive searches for new physics beyond the Standard Model of particle physics. The Any Light Particle Search (ALPS) is a light shining through wall (LSW) experiment that probes interactions of photons (light) with non-Standard Model particles via a search for the disappearance of photons on one side of a wall and to reemerge on the other. The observation of such an interaction would provide a discovery of the nature of the dark matter. This award supports the ALPS II group at the University of Florida to perform final commissioning and data analysis of the first science runs of the project. The award provides diverse training opportunities for students to develop unique and transferrable skills in disciplines spanning lasers and optics, electronics, vacuum and cryogenics. The ALPS II experiment, located at the DESY laboratory in Hamburg, Germany, is the world’s most sensitive LSW experiment. The apparatus consists of two 120m-long strings of straightened 5.3 Tesla HERA dipole magnets on each side of a light-tight wall. An optical cavity is used to build up the power on one side of the wall to up to 1MW, while a second cavity is used to amplify the photon re-creation process on the other side of the wall. This experimental setup provides a more than 12 order of magnitude improvement in sensitivity over previous searches for interactions that turn photons into low-mass particles, and vice versa. These potential low-mass particles include axion-like particles, their scalar counterparts, as well as hidden-sector photons, that may contribute to, or even exclusively form, the omnipresent dark matter. The ALPS II search technique depends only on proposed fundamental interactions between photons and postulated non-standard-model particles and explores a parameter space that has been favored by recent astronomical and other observations. The result is a largely model-independent search with no assumptions about stellar evolution nor any specific dark matter particle.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.