Performance of DOFZ diode as on-line gamma dosimeter in radiation processing

In this work, we report on results obtained with two rad-hard Diffusion Oxygenated Float Zone (DOFZ) silicon diodes as on-line gamma dosimeter in radiation processing. One device was not irradiated before using as a dosimeter, while the other received a gamma pre-dose of 700 kGy. The samples irradiation was performed using a 60Co source at a dose rate of 2.50 kGy/h from 5 kGy up 275 kGy. It was investigated the dosimetric response of these devices, operating in short-circuit current mode, with respect to the sensitivity dependence on dose and charge-dose linearity. Without any pre-dose, the diode exhibited a significant sensitivity decrease due to radiation induced point-defects in the crystal bulk. Conversely, the pre-irradiated device presented very stable current signals with a relative charge sensitivity of 0.9 mC/kGy.