QUANTITATIVE-EVALUATION OF THE INTRINSIC X-RAY PEAK PROBABILITY OF A SUPERCONDUCTING TUNNEL JUNCTION WITH THE CASCADE PROCESS MODEL OF PRIMARY PHOTOELECTRONS

The electron collision cascade process of primary photoelectrons gener ated by absorbed X-rays was studied to develop a clear model of the si gnal producing process of a superconducting tunnel junction (STJ), and the intrinsic peak probability P-1 of the STJ was calculated as a fun ction of X-ray energy. X-rays of 5-18 keV were measured by a 178 mu m x 178 mu m Nb/Al-AlO2/Al/Nb STJ with the Nb electrode thickness of 200 nm and P-1 was experimentally obtained. The calculated P-1 agreed wel l with the measured one for the range of X-ray energies of 5-12 keV. T he numerical evaluation of P-1 with this model reveals that the increa ses of the electrode thickness is effective to increase P-1.