S-Cam: A spectrophotometer for optical astronomy: Performance and latest results

Abstract

S-Cam is a cryogenic optical camera for ground-based astronomy designed around a 6×6 array of superconducting tunnel junctions. It has been conceived as a technology demonstrator, aimed at proving the potential of a new generation of single photon counting detectors for ground-based telescopes and as a possible precursor to a future space-based instrumentation. The camera is based on a 6×6 array of Ta–Al Josephson junctions, operating at about 350 mK and individually read out. For each detected photon, the absorption position, the arrival time, and the corresponding energy are measured. This allows for recording an image and simultaneously obtaining spectrophotometric information from the observed objects. In this article we provide an overview of the latest cryogenic detector performance, an up-to-date description of the S-Cam system, and a summary of the results obtained both during testing at ESTEC and during actual observations at the William Herschel Telescope in La Palma (Canary Islands, Spain). An example of the novel astronomical data obtained during the latest observation campaigns (December 1999 and April 2000) is also described.

Microwave Kinetic Inductance Detectors

“…These low temperature detectors can currently deliver extremely high sensitivity in the submillimeter [14,21], and read-noise free imaging spectroscopy in the optical/UV and X-ray [8,9,22,23,24], but the array sizes are small. In order to make real progress, these arrays must con- 1.1: A comparison of the current state-of-the-art superconducting detectors.…”

Variability of the accretion stream in the eclipsing polar EP Dra

“…Our observations were taken with the second prototype of a new generation of optical detector (S‐Cam2) which uses superconducting tunnel junctions (STJs) to record the time of arrival, location on the array and, uniquely, the energy of incident photons. For details of the instrumentation, see for example Rando et al (2000). Previous observations of close binary systems made using S‐Cam2 include UZ For (Perryman et al 2001), HU Aqr (Bridge et al 2002) and IY UMa (Steeghs et al 2003).…”

Detection of multiple fluorescent labels using superconducting tunnel junction detectors

“…Quantifying the hybridization of labeled nucleic acids ͑probes͒ to immobilized target molecules in microarray format or in cells in situ ideally requires the efficient, artifactfree measurement of several fluorescent spectra simultaneously. 1 Cryogenically cooled superconducting tunnel junction ͑STJ͒ detectors [2][3][4][5][6] developed for astronomy measure the energies of individual optical photons with very low levels of internal background. The operation of a STJ is indicated schematically in Fig.…”