Physics (Internal)

CASPEr-Electric - first results and next generations

This event is part of the Preliminary Oral Exam.

Astronomical evidence suggests that most of the matter in the universe is made of particles whose properties are not understood yet. The existence of dark matter would solve this conundrum. However, only gravitational effects of dark matter have been observed far, therefore there are many possible candidates. One well motivated candidate is the axion. Experimental searches rely on its interactions with standard model particles. One of these interactions – the nucleon EDM coupling – is probed by the CASPEr-Electric experiment. An axion field creates an oscillating nuclear electric dipole moment which interacts with a static electric field. This interaction will tilt the nuclear spins similarly to an NMR experiment.

In this talk I will start with a brief introduction about the basics of dark matter, axions and describe how CASPEr-Electric operates. I will present our first results which searched for axion-like dark matter near the Compton frequency of 40 MHz (arXiv:2101.01241). Then I will cover our ongoing efforts to probe the 1 kHz – 1MHz range using SQUIDs. Ultimately I will talk about optical excitation of paramagnetic centers in a ferroelectric crystal used in CASPEr. I will cover how these centers allow us to control the relaxation times of a nuclear spin ensemble and how we can utilize this effect in the future phases of CASPEr.