31 research outputs found
First results of a cryogenic optical photon counting imaging spectrometer using a DROID array
Context. In this paper we present the first system test in which we
demonstrate the concept of using an array of Distributed Read Out Imaging
Devices (DROIDs) for optical photon detection. Aims. After the successful S-Cam
3 detector the next step in the development of a cryogenic optical photon
counting imaging spectrometer under the S-Cam project is to increase the field
of view using DROIDs. With this modification the field of view of the camera
has been increased by a factor of 5 in area, while keeping the number of
readout channels the same. Methods. The test has been performed using the
flexible S-Cam 3 system and exchanging the 10x12 Superconducting Tunnel
Junction array for a 3x20 DROID array. The extra data reduction needed with
DROIDs is performed offline. Results. We show that, although the responsivity
(number of tunnelled quasiparticles per unit of absorbed photon energy, e- /eV)
of the current array is too low for direct astronomical applications, the
imaging quality is already good enough for pattern detection, and will improve
further with increasing responsivity. Conclusions. The obtained knowledge can
be used to optimise the system for the use of DROIDs.Comment: 7 pages, 9 figures, accepted for publicaiton in A&
Superconducting tunnel junctions as photon counting detectors in the infrared to the ultraviolet
Response linearity of Nb tunnel junction detectors for photon energies from 1,5 to 6,4 KeV
Single photon detection at visible and X-ray wavelengths with Nb-Al superconducting tunnel junctions
Single photon detection at visible and x-ray wavelengths with Nb–Al superconducting tunnel junctions
Superconducting Tunnel Junctions as Photon Counting Detectors in the Infrared to the Ultraviolet
Photon counting experiments with Ta/Al superconducting tunnel junctions are presented. Single photon detection is demonstrated in the wavelength range l=200-2000 nm with a resolving power l/Dl=22-4. The response of the detector shows good linearity with photon energy. I. INTRODUCTION Superconducting tunnel junctions (STJs) are being investigated as photon counting detectors because of their predicted high energy resolving power. This quality arises from the low energy required to break Cooper pairs and to generate free charge carriers (quasiparticles) in a superconductor. Quasiparticles can be detected by the tunneling of electrons across the insulating barrier of the STJ. Calculations for Sn and Nb indicate that the initial number of quasiparticles N(E) generated by the absorption of a photon with energy E is given as [1], [2]: Here e »1.7D (with D the bandgap of the superconductor) (1) is the average energy required to generate one quasiparticle and F»0.2 is the Fano factor. Fano-li..