A method to register hidden photons with the aid of a multi-cathode counter

We propose to detect hidden photons (HPs) by using single electrons emitted from the surface of a metal cathode under the action of HPs of cold dark matter. A multiwire gas-discharge proportional counter of special design with four cathodes has been developed. Calibration measurements were performed for determining the efficiency of counting single electrons. Single-electron pulse counting rate in various detector configurations was measured. The upper limits of mixing parameter $\chi$, which characterizes the kinetic mixing of HPs and ordinary photons, are estimated.