Search for Dark Photon Dark Matter: Dark E-Field Radio Pilot Experiment

TL;DR

This paper presents a pilot experiment searching for dark photon dark matter in the 50-300 MHz range, demonstrating feasibility and setting limits on kinetic coupling, with plans to expand to higher frequencies using advanced electronics.

Contribution

It introduces a novel electromagnetic dual approach to dark photon detection, demonstrating a proof-of-concept with room temperature electronics and outlining a scalable, wide-band search strategy.

Findings

Set a limit of $ ext{ε} ext{~} 10^{-12}$ at 50-300 MHz

Demonstrated feasibility of wide-band, real-time spectral analysis for dark photon detection

Outlined a two-phase plan to extend the search to 20 GHz with improved sensitivity.

Abstract

We are building an experiment to search for dark matter in the form of dark photons in the nano- to milli-eV mass range. This experiment is the electromagnetic dual of magnetic detector dark radio experiments. It is also a frequency-time dual experiment in two ways: We search for a high-Q signal in wide-band data rather than tuning a high-$Q$ resonator, and we measure electric rather than magnetic fields. In this paper we describe a pilot experiment using room temperature electronics which demonstrates feasibility and sets useful limits to the kinetic coupling $\epsilon \sim 10^{-12}$ over 50--300 MHz. With a factor of 2000 increase in real-time spectral coverage, and lower system noise temperature, it will soon be possible to search a wide range of masses at 100 times this sensitivity. We describe the planned experiment in two phases: Phase-I will implement a wide band, 5-million channel, real-time FFT processor over the 30--300 MHz range with a back-end time-domain optimal filter to search for the predicted $Q\sim 10^6$ line using low-noise amplifiers. We have completed spot frequency calibrations using a biconical dipole antenna in a shielded room that extrapolate to a $5 \sigma$ limit of $\epsilon\sim 10^{-13}$ for the coupling from the dark field, per month of integration. Phase-II will extend the search to 20 GHz using cryogenic preamplifiers and new antennas.