The Light-Trap: A novel concept for a large SiPM-based pixel for Very High Energy gamma-ray astronomy and beyond. (arXiv:1901.05736v1 [astro-ph.IM])
<a href="http://arxiv.org/find/astro-ph/1/au:+Guberman_D/0/1/0/all/0/1">D. Guberman</a> (1,4), <a href="http://arxiv.org/find/astro-ph/1/au:+Cortina_J/0/1/0/all/0/1">J. Cortina</a> (1,5), <a href="http://arxiv.org/find/astro-ph/1/au:+Ward_J/0/1/0/all/0/1">J. E. Ward</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Espinera_E/0/1/0/all/0/1">E. Do Souto Espiñera</a> (1), <a href="http://arxiv.org/find/astro-ph/1/au:+Hahn_A/0/1/0/all/0/1">A. Hahn</a> (2), <a href="http://arxiv.org/find/astro-ph/1/au:+Mazin_D/0/1/0/all/0/1">D. Mazin</a> (2,3), ((1) Institut de Física d'Altes Energies (IFAE), The Barcelona Institute of Science and Technology (BIST), Bellaterra (Barcelona), Spain, (2) Max-Planck-Institut für Physik, München, Germany, (3) also at ICRR, The University of Tokyo, Chiba, Japan, (4) Now at Universita di Pisa, and INFN Pisa, Pisa, Italy, (5) Now at Centro de Investigaciones Energéticas, Medioambientales y Tecnológicas (CIEMAT), Madrid, Spain)
Among the main disadvantages of using silicon photomultipliers (SiPMs) in
large experiments are their limited physical area (increasing the cost and the
complexity of the readout of a camera) and their sensitivity to unwanted
wavelengths. This explains why photomultiplier tubes (PMTs) are still selected
for the largest cameras of present and future Very High Energy (VHE) gamma-ray
telescopes. These telescopes require photosensors that are sensitive to the
fast and dim optical/near-UV Cherenkov radiation emitted due to the interaction
of gamma rays with the atmosphere. Here we introduce a low-cost pixel
consisting of a SiPM attached to a PMMA disk doped with a wavelength-shifting
material, which collects light over a much larger area than standard SiPMs,
increases sensitivity to near-UV light and improves background rejection. We
also show the measurements performed in the laboratory with a proof-of-concept
textit{Light-Trap} pixel that is equipped with a 3$times$3~mm$^2$ SiPM
collecting light only in the 300-400~nm band, covering an area $sim$20 times
larger than that of the same SiPM itself. We also present results from
simulations performed with Geant4 to evaluate its performance. In addition to
VHE astronomy, this pixel could have other applications in fields where
detection area and cost are critical.
Among the main disadvantages of using silicon photomultipliers (SiPMs) in
large experiments are their limited physical area (increasing the cost and the
complexity of the readout of a camera) and their sensitivity to unwanted
wavelengths. This explains why photomultiplier tubes (PMTs) are still selected
for the largest cameras of present and future Very High Energy (VHE) gamma-ray
telescopes. These telescopes require photosensors that are sensitive to the
fast and dim optical/near-UV Cherenkov radiation emitted due to the interaction
of gamma rays with the atmosphere. Here we introduce a low-cost pixel
consisting of a SiPM attached to a PMMA disk doped with a wavelength-shifting
material, which collects light over a much larger area than standard SiPMs,
increases sensitivity to near-UV light and improves background rejection. We
also show the measurements performed in the laboratory with a proof-of-concept
textit{Light-Trap} pixel that is equipped with a 3$times$3~mm$^2$ SiPM
collecting light only in the 300-400~nm band, covering an area $sim$20 times
larger than that of the same SiPM itself. We also present results from
simulations performed with Geant4 to evaluate its performance. In addition to
VHE astronomy, this pixel could have other applications in fields where
detection area and cost are critical.
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