Energy Linearity Change of the NaI(Tl) Detector with the Time of use as Evidence of Changing the Structure of Dynodes

Abstract

In this paper, we studied the energy linearity of two identical NaI(Tl) detectors, one new (unused) and the other old (long-term), to determine if there was a change in the structure of the NaI(Tl) detectors. For any supply voltage, we found from the dependence on channel number to the source energy that the slope for the old detector is greater than the new detector, indicating an increase in the secondary emission factor with the time of use. That is meaning a change in the behavior of the Cs-Sb mixture from semiconductor to conductor. The average deviation  of the channel number for the old detector is greater than the new one, indicating the detector linearity is becoming worse with the time of use. That is meaning the conductor may be partially and random constructed in the mixture.

Keywords: energy linearity, dynodes, Cs-Sb mixture.