The Silicon Drift Detectors (SDDs) provide, through the measurement of the drift time of the charge deposited by the particle which crosses the detector, information on the impact point and on the ...energy deposition. The foreseen readout scheme is based on a single chip implementation of an integrated circuit that includes low-noise amplification, fast analog storage and analog to digital conversion, thus avoiding the problems related to the analog signal transmission. A multi-event buffer that reduces the transmission bandwidth and a data compression/zero suppression unit complete the architecture.
In this paper the system components design is described, together with the results of the first prototypes.
The operating principle of an electric system able to compensate in real time the differences in time-of-flight due to the path-length spread occurring in large devices with pointlike geometries is ...described. Experimental tests with a particle beam have provided very good results, opening the possibility of triggering with very long scintillators with time resolutions of the order of 1 ns. It is concluded the system completely fills the requirements of the OBELIX experiment, extending the range of pi /k separation from approximately=300 to approximately=600 MeV/c.< >
The ToPiX ASIC is a custom development for the electronic readout of the silicon pixel detector for the PANDA experiment. The ASIC has to cope with a particle rate of up to 6.1 × 10 6 particles/s and ...with the absence of a trigger signal, thus dramatically increasing the amount of data to be transmitted. A reduced scale prototype with four 128 cells, four 32 cells columns, end of column logic and serial output has been designed in a CMOS 0.13 μm technology and tested. The ASIC measures both the hit arrival time and the charge released via a Time over Threshold technique.
We have designed a silicon detector to measure the angular distribution and the multiplicity of charged secondaries produced in high-energy PbPb interactions. It will be used to characterize the ...events in the NA50 experiment. The experiment will have to function at very high rate, and the silicon detectors will have to operate in the high-radiation area close to the target.
Therefore, the detector will have to be very fast (dead time below 50 ns), radiation resistant (up to the Mrad level as dose and up to more than 1013 particles/cm2 as non-ionizing damage) and of high granularity. The conditions on noise, speed and radiation hardness are comparable to the ones foreseen at the future Large Hadron Collider at CERN.
We present here the detector design, discuss some of the solutions which have been investigated and report first results on the components of the system which have been designed and produced up to now.
The requirements for the PANDA Micro Vertex Detector in terms of track density and absence of a trigger signal lead to the need of a custom solution for the electronic readout of the silicon pixel ...detectors. A reduced scale prototype with two 128 cells and two 32 cells columns has been designed in a CMOS 0.13 μm technology and successfully tested. The ASIC measures the 2-D position, the hit arrival time and the charge released via a Time over Threshold technique.
In six healthy males, aged 25.3 +/- 0.66, the pituitary and adrenal simultaneous response to CRF (1 microgram/kg), TRH (200 micrograms) and LH-RH (100 micrograms) was studied at the following times ...of different days: 0400, 0800, 1200, 1600, 2000 and 0000. Each test was preceded by a 8-hr fast after a meal containing 600 cal (CHO 50%, lipid 30%, protein 20%). The interval between two consecutive tests was 52 hrs and the starting time was randomized. The serum cortisol was measured before and after 60, 120, 180, 240 min. Serum TSH, Prolactin, FSH and LH were measured before and after 5, 10, 15, 30, 60, 90 and 120 min. The statistical analysis was reported by both mean chronograms (as absolute values and relative change or absolute difference from mesor) and mean cosinor on basal values and total (T.A.) or incremental (I.A.) areas after RH stimulus. Serum cortisol: a statistically significant circadian rhythm was found for basal values with a peak in the morning (phi at 1040; 95% C.L. 0808-1438). T.A. after RH stimulus as well appeared statistically higher again in the morning, whereas the I.A. presented an opposite phase with higher values at night (phi at 2133; 95% C.L. 2055-0312). Serum Prolactin: mean chronogram analysis showed significantly higher basal values at 0800 and lower values at 1600, whereas I.A. were significantly lower in the morning. Serum LH: basal values were statistically higher in the morning, while T.A. and I.A. showed an opposite behaviour with peaks in the night (T.A.: phi at 2015, 95% C.L. 1710-0035; I.A.: 0 2033; 95% C.L. 1736-0004).
Seven female subjects in whom thyroid hemiagenesis was suspected on the basis of clinical findings and scintiscanning before and after TSH administration were studied with ultrasound. Ultrasonic ...scanning confirmed true hemiagenesis in only three cases. In the other four it revealed a nonfunctional hypoplastic lobe contralateral to the assumed single lobe.
A detailed study of charge collection efficiency has been performed on the Silicon Drift Detectors (SDD) of the ALICE experiment. Three different methods to study the collected charge as a function ...of the drift time have been implemented. The first approach consists in measuring the charge at different injection distances moving an infrared laser by means of micrometric step motors. The second method is based on the measurement of the charge injected by the laser at fixed drift distance and varying the drift field, thus changing the drift time. In the last method, the measurement of the charge deposited by atmospheric muons is used to study the charge collection efficiency as a function of the drift time. The three methods gave consistent results and indicated that no charge loss during the drift is observed for the sensor types used in 99% of the SDD modules mounted on the ALICE Inner Tracking System. The atmospheric muons have also been used to test the effect of the zero-suppression applied to reduce the data size by erasing the counts in cells not passing the thresholds for noise removal. As expected, the zero suppression introduces a dependence of the reconstructed charge as a function of drift time because it cuts the signal in the tails of the electron clouds enlarged by diffusion effects. These measurements allowed also to validate the correction for this effect extracted from detailed Monte Carlo simulations of the detector response and applied in the offline data reconstruction.
