Tunnel junction used as thermometer for ions detection

We propose the use of a superconductor — normal metal tunnel junction as thermometer for the energy measurement on MeV ions, using a metallic bolometer. The direct measurement of electronic temperature leads to a small time constant even at very low temperature in contrast with systems where the time constant is limited by electronphonon interaction. Experiments with heat pulses obtained by LED and optical fibre confirm the calculated time constants. Sensitivity calculations using the measured data gives an energy resolution better than 1/1000 for 1MeV ions with a time constant of 50 µs.