The Detection of Alpha Particles With Superconducting Tunnel Junctions

Abstract

A superconducting thin film tunnel junction (Sn–SnO2–Sn) of total thickness 400 nm, area 7 × 10−4 cm2, and normal (4.2 K) resistance 77 m? was prepared on a glass substrate. When cooled to 1.2 K and suitably electrically and magnetically biased, the junction was bombarded with 5.1 MeV alpha particles. The resulting pulses induced in the tunnel current were observed to have amplitudes up to 19 times the r.m.s. output noise level. The possibility of utilizing this effect in charged particle spectrometry is explored.

Inclusive Model-Based X-ray Detection Characteristics of Superconducting Tunnel Junctions

“…2. The number of quasiparticles is postulated to decrease with a time constant T, when they are located in a superconducting layer (1). The constant T, represents effects of surface trap, escape to current, lead, and phonon escape.…”

“…The number The quasiparticles appearing in layer ( 2 ) have the same tunneling probability as in layer (l), and the further back tunneling again generates quasiparticles in layer (1). In this case the statistical fluctuation in the number of charge carriers may increase to some extent.…”

“…The first experimental data were given by Wood and White in 1973('). After their pioneer work, technique has advanced in junction fabricat,ion, and a lot of experimental studies on X-ray detection have been reported for such tunnel junctions as tin, niobium, tantalum and aluminum, as described in the following s e~t i o n (~) -(~) .…”

<title>Progress on detectors with superconducting tunnel junctions</title>

“…6 Thereby, the statistics of charge carriers is improved. Superconductors offer an energy gap reduced by a factor of 1000 compared to semiconductors.…”

“…Thereafter, the detector is removed from the vacuum system and the unwanted lift-off structures removed. 6. ELECTRONIC NOISE…”