Speaker
Dr
Carlos Maximiliano Mollo
(INFN)
Description
Photosensitive devices represent a key solution for several current and future categories of experiments in which light detection can be considered the main channel of observation for physical phenomena. The process of increasing the experimental sensitivity above the current limits is steering the development of experiments whose sizes should greatly exceed the dimensions of the largest today’s installations. In such a large scale of apparatus, no other option remains than using natural media as radiators: the atmosphere, deep packs of ice, water, big volume portions of sea, liquid gases often in tanks at cryogenic temperatures. In these (transparent) media, charged particles, originating from the interactions or decays of primary particles, radiate Cherenkov or fluorescence light, which is then detected by photosensitive devices.
In these fields of applications, the relatively new Silicon Photomultipliers (SiPM) based on the limited Geiger-mode avalanche (generally G-APD, Geiger Avalanche Photons Detectors), are starting to be extensively studied in view of their future utilization. Nevertheless they suffer of generally a limited sensitive surface currently between 1 to 9mm2: intrinsic noise depends linearly with the surface, so quadratically with the dimensions and can reach undesired thresholds.
A solution to increase SiPM optical performances can be using Optical Concentrators with the correct refraction index, characteristic and geometry in order to improve the aperture angle of view of the device. The use several SiPM of small, say, acceptable intrinsic dimensions (i.e. 3x3 mm2 4x4 mm2) arranged in a matrix-shaped array and equipped of light concentrators to form a sort of “gem” sensitive to light. A correct electronic equipment could transform such a “gem” into a modular and flexible light detector applicable in several situations. Indeed larger surface detector can be realized using a matrix of G-APD pixels by focusing the light to sensitive area of single SiPM. Such a layout, in which the dead area between the sensitive surfaces of the individual detector may be taken care of, is very promising for application in field of modern imaging Cherenkov detector.
Author
Dr
Carlos Maximiliano Mollo
(INFN)
