Joesphson device for simultaneous time and energy detection

The development of a detection device for simultaneous measurement of energy and impact time, to be used in time-of-flight mass spectrometry, is reported. In this device, two superconducting tunnel junctions are coupled through a passive network. The first junction operates in the quasiparticle regime in order to measure the energy of a molecule impact and to act as a proportional detector. The second one operates in the Josephson regime in order to act as a fast discriminator for the impact time of a molecule impinging on the detector junction. In this way, a very accurate time determination can be achieved limited only by the intrinsic detector response, thus improving the spectrometer mass resolution. To demonstrate the feasibility of this detection scheme in mass . spectrometry, calibration measurements have been carried out using a 55Fe x-ray source to simulate the molecule impact. The experimental results successfully demonstrated simultaneous detection of energy and arrival time in coincidence with photon impacts, with a time resolution limited, in practice, only by the electronics used.