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Silicon detectors for the Roman Pots of the the large hadron collider TOTEM experiment aim for full sensitivity at the edge where a terminating structure is required for electrical stability. This work provides an innovative approach reducing the conventional width of the terminating structure to less than 100 pm, still using standard planar fabrication technology. The objective of this new development is to decouple the electric behavior of the surface from the sensitive volume within a few tens of micrometers. The explanation of the basic principle of this new approach together with the experimental confirmation via electric measurements and beam test are presented in this paper, demonstrating that silicon detectors with this new terminating structure are fully operational and efficient to under 60 μm from the die cut. [ABSTRACT FROM AUTHOR]

A monolithic X- and gamma-ray detector based on a silicon drift detector coupled to a CsI(TI) scintillator is presented. The detector is operated both as a direct X-ray detector for photons interacting in silicon and as an indirect detector for photons interacting in the scintillator. As interactions in silicon and in CsI yield different amount of charge per unit energy deposited, discrimination of the place of interaction is necessary to obtain the correct energy. Discrimination of the interaction type is carried out by means of pulse shape discrimination performed with two parallel processing chains with different shaping times. In this paper an extensive characterization of the detector with temperature is presented. It is shown that cooling the detector at 10 ° allows to obtain a nearly 100% efficiency between 8 and 200 keV. Further cooling below 0 °C allows pulse shape discrimination with 100% accuracy throughout the detector's energy range. The detector has also been tested with X-rays at various energies by means of a tun- able X-ray facility. These tests allowed an investigation of the light yield nonproportionality in CsI(Tl) at low energies, necessary for a proper energy calibration of the detector. [ABSTRACT FROM AUTHOR]

In this paper, a charge preamplifier designed to achieve high stability in spectroscopic measurements at different counting rates is presented. The preamplifier operates with the input JFET and the feedback capacitor directly integrated on the silicon detector, in the specific case a Silicon Drift Detector (SDD). The motivation of the work is to overcome the peak shift, typically in the order of few percents and then comparable with the energy resolution achievable at 6 keV with a SDD, which can be measured when the on-chip JFET is operated in the conventionally used source follower configuration. In the proposed circuit, the SDD anode voltage is stabilized by means of a low-frequency feedback loop which operates according to the "drain feedback" technique. Moreover, the implemented design, differently from previous designs also based on a continuous reset of the leakage + signal currents, allows to obtain a sufficiently fixed decay time constant of the preamplifier with respect to event rate variations. This feature allows to maintain an optimal pole-zero compensation by the shaping amplifier when the event rate changes relevantly during the measurement. In an experimental characterization of the preamplifier with a SDD, a Mn-Kalpha peak-shift within ±0.03% (i.e., ±2 eV at 6 keV) has been measured changing the rate from few kcounts/s up to 400 kcounts/s. [ABSTRACT FROM AUTHOR]

A large detector structure, called a supermodule, was developed for the CDF Run lib silicon strip detector. The supermodule is a compact mechanical, thermal, and electrical unit, which is ideally suited for construction and assembly of large volume detector systems. Its dense packaging requires careful suppression of possible electromagnetic interference due to power, clock, control, and data bus activity. We study the coupling of the magnetic fields caused by a clock signal through an aluminum shield into the silicon strips. Analytical and numerical calculations of the resulting interference signal are presented, and its shape and size are estimated. The calculations are in fair agreement with electrical performance measurements taken with final design supermodules. Calculations and measurements show that the interference effect can be effectively suppressed by a thin aluminum shield. [ABSTRACT FROM AUTHOR]

Silicon detectors with a fine segmentation (micropixel and microstrip) are the main type of detectors used in the inner trackers of Large Hadron Collider (LHC) experiments. Due to the high luminosity of the LHC machines they are required to have a fast response to fit the short shaping time of 20 ns and to be radiation hard. Evaluation of silicon microstrip detectors developed for the ATLAS silicon tracker and carried out under collaboration of CERN and Joffe Physico-Technical Institute has shown the reversal of the pulse polarity in the detector response to short-range radiation. Since the negative signal is of about 30%-60% of the maximal positive one, the effect strongly reduces the charge collection efficiency even in nonirradiated detectors. The investigation presents the consideration of the origin of a negative response in Si microstrip detectors and the experimental proof of the model. The study of the effect has been carried out using "baby" strip detectors with a special design: each strip has a window in a metallization, which covers the p+ implant. The scan of a laser across the strips clearly shows that the negative response is observed along the scan in the interstrip gap. As soon as the light spot is placed on the strip p+ implant the negative response disappears and the value of the charge collected by the active strip proportionally increases. A phenomenological model considers the origin of the negative response as the effect of carrier trapping at the Si-SiO2 interface between the strips. [ABSTRACT FROM AUTHOR]

We present a CMOS preamplifier-shaper circuit designed to be used with low-noise solid-state detectors, like silicon drift detectors (SDDs), in X-ray Spectroscopy and γ-ray imaging applications. The circuit is composed of a low-noise preamplifier and by a sixth-order semi-Gaussian shaping amplifier with four selectable peaking times from 1.7 μs up to 6 μs. The integrated time constants used for the shaping are implemented by means of a recently proposed "RC" cell. This cell is based on the demagnification of the current flowing in a resistor ft thanks to the use of current mirrors. The particular solution adopted here allows a precise and stable implementation of the desired time constant, for given values of ft and C , and guarantees low-noise performances of the shaping amplifier when used with a cooled SDDs or other solid-state detectors with low leakage current. In this work, the main features of the circuit are first presented. The experimental results obtained with a prototype realized in the 0.35-μm 3.3-V CMOS austriamicrosystems technology are then reported and discussed. The energy resolution measured using the chip with a SDD cooled at -10 °C is 150 eV at 6 keV which corresponds to an electronics noise of 10.8 e-rms. [ABSTRACT FROM AUTHOR]