Annular Josephson junctions for radiation detection: fabrication and investigation of the magnetic behaviour

We have fabricated and characterised superconducting tunnel junctions with annular geometry for radiat ion detection. The advantage of the annular geo metry is that, once the trapping has occurred the magnetic field can be swi tched off and there is no need to further sustain any parallel magnetic fie ld during the detector working time. In agreement with our previous theoret ical prediction we have observed the suppression of the Josephson critical current and the presence of one single resonance step in the I-V characteri stic when magnetic fluxons were trapped in the: central hole of the junctio n. (C) 2000 Elsevier Science B.V. All rights reserved.