Speaker
Dr
Peter Kodys
(Charles University)
Description
Progress of charge collection measurement of irradiated strip detectors with a laser in low temperatures will be presented. The tests use four custom made preamplifiers connected to group of strips and an automatic data acquisition. The laser generator of infrared light (wavelength 1066 nm) is connected to a box with electronics and detector via an optical fiber and defocusser to generate large laser spot covering many strips. Hence, light intensity on each strip is similar to each other. Data acquisition was performed with a digitizer DRS4 V2 triggered by a pulse generator. Whole box is situated in a freezer where the temperature is about -30 degrees of Celsius. The temperature is monitored by a thermometer probe placed close to the detector. Data are recorded using DRS digitizer software at frequency 200 - 300 Hz.
The tested sensors are ATLAS07 minis (10x10mm) of different designs, irradiated to different doses. In this presentation we will show results of charge collection measurement as a function of bias voltage. Bias current and response of one strip or average from all 4 measured strips was recorded. As a reference unirradiated detector W12-Z6-P22 was measured at several temperatures (room temperature, -22 C and -31 C). Sensors W13-BZ4A-P04, W13-BZ4D and W13-BZ4B were irradiated by dose 2x10^15 cm-2, sensor W12-BZ4D-P22 by 4x10^14 cm-2 and sensor W13-BZ5-P11 by 1x10^16 cm-2. For unirradiated sensors, as well as for sensors irradiated to 1.3x10^14 and 4x10^14 n/cm2 the bias dependence of the collected charge reached plateau corresponding to the full depletion voltage as found from the CV scan.
Author
Dr
Peter Kodys
(Charles University)
