John E. Ward - Light-Trap: A SiPM Upgrade for VHE Astronomy and Beyond

Wednesday 31 May 2017, 13:00 → 14:00 Europe/Madrid

Seminar (IFAE)

Joern Lange (IFAE Barcelona), Michael Leyton (IFAE), Stefano Terzo (IFAE)

With the development of the Imaging Atmospheric Cherenkov Technique (IACT), Gamma-ray astronomy has become one of the most interesting and productive fields of astrophysics. Current IACT telescope arrays (MAGIC, H.E.S.S, VERITAS) use photomultiplier tubes (PMTs) to detect the optical/near-UV Cherenkov radiation emitted due to the interaction of gamma rays with the atmosphere. For the next generation of IACT experiments, the possibility of replacing the PMTs with Silicon photomultipliers (SiPMs) is being studied. Among the main drawbacks of SiPMs are their limited active area (leading to an increase in the cost and complexity of the camera readout) and their sensitivity to unwanted wavelengths. To overcome these shortcomings, a novel method to build a relatively low-cost pixel consisting of a SiPM attached to a PMMA disk doped with a wavelength shifter was proposed. This pixel collects light over a much larger area than a single standard SiPM and improves sensitivity to near-UV light while simultaneously rejecting background. The concept, simulation results and laboratory measurements of a Light-Trap pixel prototype, as well as a brief description of field tests performed with a 7-pixel cluster that was recently installed in a MAGIC telescope camera will be presented.