Johannes Ulrichs | Searcharxiv

arXiv2024

WISP Searches on a Fiber Interferometer under a Strong Magnetic Field

A novel table-top experiment is introduced to detect photon-axion conversion: WISP Searches on a Fiber Interferometer (WISPFI). The setup consists of a Mach-Zehnder-type interferometer with a fiber placed inside an external magnetic field, where mixing occurs and is detected by measuring changes in amplitude. Hollow-core photonic crystal fibers (HC-PCF) will be used to achieve resonant mixing that is tuneable by regulating the gas pressure in the fiber. An unexplored axion mass-range (28 meV to 100 meV) can be probed reaching the two-photon coupling expected for the QCD axion.

hep-ex↗

arXiv2023

First results from BRASS-p broadband searches for hidden photon dark matter

We discuss first results from hidden photon dark matter searches made with a prototype of the Broadband Radiometric Axion/ALPs Search Setup (BRASS-p) in the range of particle mass of 49.63-74.44 $μ$eV (frequency range of 12-18 GHz). The conceptual design of BRASS and a detailed description of its present prototype, BRASS-p, are given, with a view of the potential application of such setups to hidden photon, axion, and axion-like particle (ALP) dark matter searches using heterodyne detectors in the range of particle mass from 40$μ$eV to 4000$μ$eV (10 GHz to 1 THz). Pioneering measurements made with BRASS-p achieve the record sensitivity of (0.3--1.0)$\times$$10^{-13}$ to the kinetic mixing between the normal and hidden photons, assuming the dark matter is made entirely of unpolarized hidden photons. Based on these results, a discussion of further prospects for dark matter searches using the BRASS-p apparatus is presented.

hep-ex↗