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&

Instrument description and performance of the Imaging Gamma-Ray Telescope COMPTEL aboard the Compton Gamma-Ray Observatory

The COMPTEL instrument aboard the COMPTEL Gamma-Ray Observatory and its performance capabilities are described. Calibration data are used to determine the angular and energy response, and the effective detection area. The imaging properties of COMPTEL are demonstrated, and the sensitivity of Comptel to celestial gamma-ray sources are estimated from flight data

Dordrecht Ondergronds 4

Het project omvat de opgraving van een deel van verspoeld/geerodeerd nederzettingsterrein uit de Late Middeleeuwen in het buitengebied van Dordrecht. Het gaat om de vermoedelijke resten van het dorp Kruiskerke/Wolbrandskerke dat op de zuidoever van de Dubbel lag en tijdens de St. Elisabethsvloed van 1421 is verlaten en onder water komen te staan. Tijdens het onderzoek zijn resten gevonden van de kerk en kerkhof, mogelijk de dijk en twee duikers, sloten (met beschoeiingen) en enkele (mest)kuilen en een mogelijke staander van een eventuele huisplaats