Development of superconducting tunnel junction photon detectors with cryogenic preamplifier for COBAND experiment

Abstract

We present the status of the development of Superconducting Tunnel Junction (STJ) detector with the cryogenic preamplifier as far-infrared single photon detector for the COsmic BAckground Neutrino Decay search (COBAND) experiment. The photon energy spectrum from the radiative decay of the cosmic background neutrino is expected to have a sharp cutoff at high energy end in a far-infrared region ranging from 15 meV to 30 meV. The detector is required to measure an individual photon energy with a sufficient energy resolution less than 2% for identifying the cutoff structure, and to be designed for a rocket or satellite experiment. We develop an array of Nb/Al-STJ pixels which can detect a single far-infrared photon delivered by a diffractive grating according to its wavelength. To achieve high signal-to-noise ratio of the STJ, we use a preamplifier made with the Silicon-on-Insulator (SOI) technique that can be operated around 0.3K. We have developed the Nb/Al-STJ with the SOI cryogenic preamplifier and have tested the detector performance around 0.3K.