Dresden 2006 – wissenschaftliches Programm
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TT: Tiefe Temperaturen
TT 24: Superconductivity: Cryodetectors
TT 24.9: Vortrag
Mittwoch, 29. März 2006, 18:45–19:00, HSZ 02
Energy loss in down-conversion process in thin superconducting films — •Alexander Kozorezov — Department of Physics, Lancaster University, Lancaster, UK
We have developed theory of photoelectron energy down-conversion in thin superconducting films. Presence of interfaces at a distance which may be comparable to mean free paths for pair-breaking phonons is an important factor allowing pair breaking phonons to escape from the film. Both mean number of quasiparticles generated in the down-conversion process and their fluctuations depend on details of down-conversion process in the vicinity of interface. Theory predicts important contributions to both statistical fluctuations of generated quasiparticles through phonon escape noise and inhomogeneous broadening effects originating from the initial spatial distribution of photoelectrons. We discuss extra limitations to resolving power of single photon detectors based on superconducting tunnel junctions and TES microcalorimeters. Good agreement between theory and experiment for Ta/Al/AlOx/Al/Ta superconducting tunnel junctions is demonstrated. Implications for optimum design of single photon spectroscopic arrays are discussed.