A hot-electron direct detector for radioastronomy
Boris S. Karasik, William R. McGrath, Henry George LeDuc +1 more
A hot-electron transition-edge superconducting bolometer with adjustable thermal relaxation speed is proposed. The bolometer contacts are made from a superconductor with high critical temperature which blocks the thermal diffusion of hot carriers into the contacts. Thus electron-phonon interaction is the only mechanism for heat removal. The speed of thermal relaxation for hot electrons in a nanometre-size superconducting bolometer with T c = 100-300 mK is controlled by the elastic electron mean free path l . The relaxation rate behaves as T 4 l at subkelvin temperatures and can be reduced by a factor of 10-100 by decreasing l . Then an antenna- or waveguide-coupled bolometer with a time constant ~10 -3 -10 -4 s will exhibit photon-noise-limited performance at millimetre and submillimetre wavelengths. The bolometer will have a figure of merit NEP 1/2 = 10 -23 -10 -22 J -1 at 100 mK which is 10 3 -10 4 times better (i.e. smaller) than that of a state-of-the-art bolometer. A tremendous increase in speed and sensitivity will have a significant impact for observational mapping applications.
Superconductor Science and Technology•Nov 1, 1999•41 citations