MECHANISM OF PICOSECOND RESPONSE OF ANTIGRANULOCYTES YBACUO FILMS TO ELECTROMAGNETIC-RADIATION

The ultrafast mechanisms of radiation detection in granular YBaCuO films are studied in the wide wavelength range from millimeter to near infrared. With the rise of radiation frequency the Josephson detection at the grain boundary weak links is replaced by electron heating into the grains. This change occurs in the submillimeter wavelength range. Electron-phonon relaxation time tau(eph) is determined from direct measurements, quasi-stationary electron heating measurements and frequency dependense of current, at which maximum voltage shift is observed. Temperature dependence of tau-eph at T less-than-or-equal-to 40 K was found to be tau-eph approximately T-1. The results show that detectors with the response time of few picoseconds at nitrogen temperature are attainable.