An induced annealing technique for SiPMs neutron radiation damage

Abstract

The use of Silicon Photo-Multipliers (SiPMs) has become popular in thedesign of High Energy Physics experimental apparatus with a growinginterest for their application in detector area where a significantamount of non-ionising dose is delivered. For these devices, the maineffect caused by the neutron fluence is a linear increase of the leakagecurrent. In this paper, we present a technique that provides apartial recovery of the neutron damage on SiPMs by means of anElectrical Induced Annealing. Tests were performed, at the temperature of 20°C, on a sample ofthree SiPM arrays (2×3) of 6 mm2 cells with 50 μmpixel sizes: two from Hamamatsu and one fromSensL. These SiPMs have been exposed to neutrons generated by the Elbe Positron Source facility (Dresden),up to a total fluence of 8 × 1011 n1 MeV-eq/cm2. Our techniques allowed to reduced the leakagecurrent of a factor ranging between 15-20 depending on the overbiasused and the SiPM vendor. Because, during the process theSiPM current can reach O(100 mA), the sensors need to be operated in a condition thatprovides thermal dissipation. Indeed, caution must be used when applying this kind ofprocedures on the SiPMs, because it may damage permanently the devices themself.