A Transient Current Technique was used to evaluate non-irradiated and irradiated p-type silicon micro-strip detectors. The beam was parallel with the surface and perpendicular to the strips (Edge-TCT) so that electron hole pairs were created at known detector depth. Induced current pulses were measured in one of the strips and analyzed in a new way, not requiring the knowledge of trapping times, to determine drift velocity, charge collection and electric field profiles. Strong evidence for charge multiplication was found with the detector irradiated to the highest fluence.
COBISS.SI-ID: 23910695
Charge collection measurements with silicon detectors with implanted n-type readout strips in p-type silicon bulk (n+-p) are presented. Detectors were irradiated with 191 MeV pions at the Paul Scherrer Institute (PSI) in Villigen in Switzerland. Signals induced by electrons from 90Sr source were measured with SCT128 chip. Collected charge and detector current were measured after several annealing steps summing up to over 10000 minutes at 60°C. It was observed that irradiation of these detectors with pions results in only ~ 30% of the increase of Vfd seen after irradiation with neutrons to the same NIEL equivalent fluence. Charge multiplication effects in pion irradiated detectors were seen only after long accelerated annealing time. Both effects are consistent with smaller space-charge introduction rates after irradiation with charged hadrons, characteristic for oxygenated detector material. It was confirmed that, at sufficient bias voltage, reverse annealing after pion irradiation does not represent a problem for application of these detectors in trackers at upgraded LHC.
COBISS.SI-ID: 25309735
A new hybrid avalanche photo-detector has been developed for the Belle RICH counter. The basic features of this device were examined with and without a magnetic field. By constructing a RICH prototype counter using 6 photo-detectors, we carried out a test beam experiment to confirm the performance. We obtained a single photon Cherenkov angle resolution of 12.8 mrad with 4.6 photo-electrons in our experimental setup, demonstrating that 4σπ/K separation at 4 GeV/c was achieved.
COBISS.SI-ID: 24016423
We describe the design, construction and performance of electronics for the readout of a hybrid avalanche photodiode (HAPD). The HAPDs are being studied as possible candidates for the detection of Cherenkov rings in a proximity focusing ring imaging Cherenkov (RICH) detector, which is foreseen for the upgrade of the Belle spectrometer at the KEKB collider.
COBISS.SI-ID: 24453159
Miniature micro-strip detectors made by implanting n-type readout strips on p-type silicon bulk (n+p) were irradiated with reactor neutrons up to fluences of 5∙1015 neq/cm2. Their charge collection properties were measured with signals caused by fast electrons from 90Sr source and read out by SCT128A chip. Collected charge and detector current were measured up to high bias voltages of 1400 V at which signs of charge multiplication can be observed. Detectors were submitted to several annealing steps at 60°C up to total time of 5040 minutes. It was measured that annealing influences the onset of the multiplication processes. Beneficial annealing lowers the electric field in detectors and therefore reduces the portion of collected charge resulting from multiplication whereas the opposite can be observed after reverse annealing effects prevail. Therefore an increase of collected charge with annealing time was measured at high bias voltages. A similar effect can be observed in the leakage current, which at high voltages increases with reverse-annealing time.
COBISS.SI-ID: 24427303