Speaker
Description
The study of a Low Gain Avalanche Detector (LGAD) has been carried out by Ion Beam Induced Charge (IBIC) and Time Resolved Ion Beam Induced Charge (TRIBIC) using the nuclear microbeam line of the Centro Nacional de Aceleradores (CNA). For that purpose, a 3 MeV H ion beam was employed, and the results were compared to that obtained by the Transition Current Technique (TCT) using an infrared laser at the SSD laboratory at CERN and at the Clean Room of the Physics Institute of CAntabria (IFCA). Although the charge collection time is the same for both techniques, near the onset voltage the shape of the induced current pulses is significatively different. Moreover, the values of the absolute gain curve are considerably higher when measured by TCT. This gain suppression is related to the shielding effects of the electric field in the multiplication layer, which depend on the generated carrier density. Therefore, in order to study how the plasma effects change with the generated carrier density, experiments have been carried out by varying the proton incidence angle from 0° to 85°.
In this talk, the gain curves for all angles will be shown. The results indicate that when mean ionization density projected on the multiplication layer is minimum (50°) the measured gain is maximum. Also, at very large angles (> 70°) the electron path in the multiplication layer is the dominant factor for the gain suppression. TRIBIC results will also be shown, from which some conclusions can be drawn about the decrease in the hole gain and plasma effects outside the multiplication layer when the Bragg peak falls inside the detector.
