First Results from a Broadband Search for Dark Photon Dark Matter in the 44 to $52\mathrm{\mu }\mathrm{eV}$ Range with a Coaxial Dish Antenna

We present first results from a dark photon dark matter search in the mass range from 44 to $52\mathrm{\mu }\mathrm{eV}$ (10.7–12.5 GHz) using a room-temperature dish antenna setup called GigaBREAD. Dark photon dark matter converts to ordinary photons on a cylindrical metallic emission surface with area $0.5{\mathrm{m}}^2$ and is focused by a novel parabolic reflector onto a horn antenna. Signals are read out with a low-noise receiver system. A first data taking run with 24 days of data does not show evidence for dark photon dark matter in this mass range, excluding dark photon photon mixing parameters $\chi \gtrsim {10}^{-12}$ in this range at 90% confidence level. This surpasses existing constraints by about 2 orders of magnitude and is the most stringent bound on dark photons in this range below $49\mathrm{\mu }\mathrm{eV}$.

Figure 1

Experimental setup. DPs convert to photons emitted perpendicularly from the cylinder. The signal is focused on a coaxial horn antenna, amplified using a low-noise receiver chain (right), down-converted and digitized using a custom real-time field-programmable gate array based broadband DAQ (bottom).

Figure 2

Focal spot measurements vs vertical horn antenna position $z$ and frequency. (a) Expected DP signal from a full-wave Comsol^® simulation. (b) Measured reflectivity. (c) Measured system noise temperature. The focus is symmetric around $z=0$ (bold dotted line). Standing wave resonances between barrel and horn antenna can be swept over frequency by adjusting the horn antenna position between $\mathrm{z}\approx 10\mathrm{mm}$ and $z\approx -10\mathrm{mm}$ (faint dotted lines).

Figure 3

(a) Observed excess power $P_0$ vs rf frequency, normalized with receiver gain and detection efficiency. No signal exceeds a global significance of $3\sigma$. (b) Distribution of the observed excess powers $P_0$ divided by the expected standard deviation from thermal noise $\sigma$, following a normal distribution. (c) Observed excess power for the test signal injected between June 16 and June 20 vs horn antenna position showing the expected weak resonant enhancement.

Figure 4

DP parameter space excluded in this work (GigaBREAD-0), compared to cosmological constraints, other dish antennas like SHUKET [24], QUALIPHIDE [26], BRASS-p [28], and DOSUE [27, 29], and other haloscopes [55] over about two decades in mass (left) and magnified (right).