Speaker
Description
Owing to its excellent radiation hardness, diamond has been widely used as solid-state particle detectors and dosimeters in high-radiation environments. A system based on single-crystal synthetic-diamond detectors has been developed and installed in order to monitor the radiation level and detect beam losses near the interaction region of the SuperKEKB collider for the the Belle II experiment.
In order to assess the crystal quality and response of these devices, all diamond sensors are characterized with different radiation sources, comparing the measurement results with dedicated simulations. We devised a novel current-to-dose-rate calibration method for steady irradiation, which employs a silicon diode as a reference in order to greatly reduce uncertainties associated with the radiation source. The calibration results, in agreement between and X radiation, span a dose rate range from tens of nrad/s to rad/s.
In addition, beam tests of the devices are being carried out at the linac of the FERMI@Elettra FEL in Trieste (Italy), with short 1GeV electron bunches of 1ps duration and bunch charge from one to hundreds of . The aim is to test the transient response to very high intensity pulses and study possible saturation effects due to a very high charge carrier density in the diamond bulk.
A two-step numerical simulation approach is employed to study the time response of the diamond sensor, separating the effects of charge carriers drifting in the diamond bulk from the effects of the circuit on the signal shape.
Validation of the approach is conducted by comparing the simulation with measurements of the TCT (Transient Current Technique) signals generated by particles.
Preliminary results show remarkable agreement between measurements and numerical simulation, where the diamond resistance is modeled as a function of the variable charge density in the diamond bulk.
