Radiation hard position-sensitive cryogenic silicon detectors: the Lazarus effect

The discovery of the so-called Lazarus effect, namely the recovery of the charge collection efficiency (CCE) of irradiated silicon detectors by means of cryogenic cooling has entailed an increasing interest in the behavior of silicon detectors at cryogenic temperatures. We have measured the CCE of a silicon p-i-n diode detector previously irradiated with an equivalent fluence of 1 × 10¹⁵ n/cm² neutrons of 1 MeV energy. The charge collection efficiency has been measured at 77 K, showing that the low-temperature operation considerably decreases the bias current. This is also the case when forward voltage bias is applied, which then becomes a suitable option. In this condition, the sample shows a charge collection efficiency in excess of 65% at 250 V corresponding to a most probable signal for a minimum ionizing particle of 21 000e^-.