# Detection of Dark Photon Decaying into $e^+e^-$ using Cherenkov Radiation

## TL;DR

This paper proposes a novel method to detect dark photons decaying into electron-positron pairs by observing Cherenkov radiation in gas, enabling low-background searches with thinner targets and simpler setups.

## Contribution

It introduces a new detection technique using Cherenkov radiation to improve dark photon searches, reducing background and allowing for more accessible experiments.

## Key findings

- Cherenkov radiation can be used to identify dark photon decay products.
- Thinner targets with Cherenkov detection reduce background noise.
- Method enables exploration of previously inaccessible dark photon parameter space.

## Abstract

In dark photon search experiments with electron beam-dumps, it is difficult to access the smaller dark photon life-time region of phase space due to enormous backgrounds from low-energy particles emerging from the target. In order to reduce the background, a thick beam-dump target is usually necessary. We propose to detect the Cherenkov radiation in gas due to ultra-relativistic electron and positron from dark photon decay. The secondary particles emerging from the beam dump have very little chance to produce such Cherenkov radiation in gas. Making use of the direction of the Cherenkov radiation, low background dark photon search with thinner target is possible. This would allow one to access challenging regions of the dark photon parameter space with low power electron beams and low-cost experimental setup.