[en] We report on the progress of a prototype hybrid photomultiplier (PMT), comprising a high QE, red extended GaAsP photocathode and an avalanche diode as electron bombarded anode with internal gain. These PMTs, with a larger cathode, are planned for the upgrade of the 17 m diameter MAGIC telescope for ground-based gamma (γ) astronomy

[en] We report on the progress of the development of a hybrid photomultiplier (PMT) with a high QE, red extended photocathode and a new, fast avalanche diode as electron bombarded anode with internal gain. The new PMT is intended to replace classical PMTs in the camera of the 17-m-diameter MAGIC telescope (The MAGIC telescope, the design study for the construction of a 17 m diameter Cherenkov telescope for γ-astronomy above 10 GeV, Max Planck Institute Report, March 1998, unpublished) for ground-based gamma-ray astronomy

[en] Photosensors are indispensable in many areas of fundamental physics research, particularly in the emerging field of particle astrophysics. They also find widespread use in medical imaging, nuclear radiation monitoring, and defense. To make significant progress in future, virtually all these areas require a new, inexpensive, high-quality industrial mass-production photosensor technology. Our group at UC Davis has been working on innovations along that line

[en] Geiger-mode avalanche photodiodes (G-APD) are promising new sensors for light detection in atmospheric Cherenkov telescopes. In this paper, the design and commissioning of a 36-pixel G-APD prototype camera is presented. The data acquisition is based on the Domino Ring Sampling (DRS2) chip. A sub-nanosecond time resolution has been achieved. Cosmic-ray induced air showers have been recorded using an imaging mirror setup, in a self-triggered mode. This is the first time that such measurements have been carried out with a complete G-APD camera.

[en] Data of the wide angle atmospheric Cherenkov light detector array AIROBICC and the scintillator matrix of the HEGRA air shower detector complex are combined to determine the energy spectrum and coarse composition of charged cosmic rays in the energy interval from 300 TeV to 10 PeV

[en] Imaging Atmospheric Cherenkov Telescopes (IACT) for Gamma-ray astronomy are presently using photomultiplier tubes as photo sensors. Geiger-mode avalanche photodiodes (G-APD) promise an improvement in sensitivity and, important for this application, ease of construction, operation and ruggedness. G-APDs have proven many of their features in the laboratory, but a qualified assessment of their performance in an IACT camera is best undertaken with a prototype. This paper describes the design and construction of a full-scale camera based on G-APDs realized within the FACT project (First G-APD Cherenkov Telescope).

[en] The maximization of the photon detection efficiency (PDE) is a key issue in the development of cameras for Imaging Atmospheric Cherenkov Telescopes. Geiger-mode Avalanche Photodiodes (G-APD) are a promising candidate to replace the commonly used photomultiplier tubes by offering a larger PDE and in addition a facilitated handling. The FACT (First G-APD Cherenkov Telescope) project evaluates the feasibility of this change by building a camera based on 1440 G-APDs for an existing small telescope. As a first step towards a full camera, a prototype module using 144 G-APDs was successfully built and tested. The strong temperature dependence of G-APDs is compensated using a feedback system, which allows to keep the gain of the G-APDs constant to 0.5%.

[en] We present a project for a novel camera using Geiger-mode Avalanche Photodiodes (G-APDs), to be installed in a small telescope (former HEGRA CT3) on the MAGIC site in La Palma (Canary Island, Spain). This novel type of semiconductor photon detector provides several superior features compared to conventional photomultiplier tubes (PMTs). The most promising one is a much higher Photon Detection Efficiency.

[en] Geiger-mode Avalanche Photodiodes (G-APD) bear the potential to significantly improve the sensitivity of Imaging Air Cherenkov Telescopes (IACT). We are currently building the First G-APD Cherenkov Telescope (FACT) by refurbishing an old IACT with a mirror area of 9.5 square meters and are constructing a new, fine-pixelized camera using novel G-APDs. The main goal is to evaluate the performance of a complete system by observing very high energy gamma-rays from the Crab Nebula. This is an important field test to check the feasibility of G-APD-based cameras to replace at some time the PMT-based cameras of planned future IACTs like AGIS and CTA. In this article, we present the basic design of such a camera as well as some important details.