Development of hardware around a silicon microstrip detector with 512 elements

The silicon chip is mounted on a ceramic substrate and connected to the preamplifiers via kapton foils. A test bench is constructed, which enables measurement of reverse current and capacitance of all strips simultaneously.     

Design equations for silicon detector ladders with heat generated by radiation damage induced leakage current

We find approximate analytical solutions to the problem of cooling a silicon detector ladder which is internally heated by leakage current caused by radiation damage. The heat generation term has an approximately exponential temperature dependence. heat is removed by convection and/or conduction to a heat sink. Design equations are derived which prevent thermal runaway, and a wide range of parameter space for those equations is explored.     

Operation of a silicon vertex detector in the NA14 photoproduction experiment

The operation and performance of a silicon vertex detector are described. The detector, which consists of a silicon multilayer active target followed by a microstrip chamber, was operated in a 1.2 T magnetic field and exposed to the NA14 high intensity photon beam. Results on the precision and efficiency of the detector for reconstruction of the interaction products are presented.     

A fast current sensitive preamplifier (MSD2) for the silicon microstrip detector

The characteristics of a hybridized low noise preamplifier are described, especially the noise performance as a function of various parameters. In particular, its behaviour in conjunction with a discriminator has been studied.     

Latest results from silicon microstrip detectors with VLSI readout for the delphi microvertex detector

A silicon microstrip counter with 25 μm strip pitch and two 128-channel low noise VLSI readout chips (“MICROPLEX”) has been tested in a 3.5 GeV negative pion beam at CERN. Results are given on the signal-to-noise ratio and on the cluster size spreading due to capacitive crosstalk.     

Heavy ion radiation damage in double-sided silicon strip detectors

A ²⁵²Cf fission fragment source was used to produce heavy-ion radiation damage in a double-sided silicon strip detector. It was found that a good quality fission fragment spectrum (as determined by the peak to valley ration N_L/N_V) could not be achieved for radiation incident on the p⁺ face of the detector. However, for radiation incident on the n⁺ face, the ratio N_L/N_V remained adequate up to an accumulated dose of 4×10⁶ fragments mm⁻². For the measurement of alphas, typical resolution deteriorated from an initial 30 keV FWHM to 50 keV FWHM at a dose of 8×10⁶ fragments mm⁻² for incident on the n⁺ face, and 6×10⁶ for radiation incident on the p⁺ face. The interstrip resistance in one region of the n⁺ face broke down completely after a relatively small radiation doses incident on that face. Further investigation of this is still required.     

A transition radiation detector for electron identification in a high energy experiment

We have built a transition radiation detector consisting of four sets of multilayered polyethylene radiators each followed by a xenon-filled proportional chamber. This detector has been used in a hadron-proton scattering experiment at CERN SPS to discriminate electrons from hadrons in the final state. Using the technique of recording chamber signals of amplitude exceeding a fixed threshold we normally achieved 0.5% pion contamination at 80% electron efficiency.     

The 40×40cm2 gaseous microstrip detector Micromegas for the high-luminosity COMPASS experiment at CERN

The measurements in the COMPASS experiment at CERN require high-resolution tracking detectors, with low radiation length and high-rate capability. For this purpose we have developed and optimized a gaseous microstrip detector `Micromegas'. Twelve planes with 1024 strips each, assembled in 3 stations of 4 views XYUV, are now being operated with success in the COMPASS environment. We describe here the performances and results obtained.     

Bias-dependent radiation damage in high-resistivity silicon diodes irradiated with heavy charged particles

High-resistivity p⁺–n–n⁺ planar diodes were irradiated with neutrons to fluences up to 2×10¹⁴ cm⁻² 1 MeV neutron NIEL equivalent and with pions to 0.47×10¹⁴ cm⁻². Special care was taken to irradiate samples under strictly controlled conditions (temperature, bias). The influence of detector biasing on the effective dopant concentration as measured with the C–V method was studied. Permanently biased diodes exhibit about two times higher |N_eff| after beneficial annealing has been completed. After switching off the bias the difference between biased and unbiased samples diminishes with a temperature-dependent annealing time. Part of the difference is attributed to a bistable defect since it recovers if the bias is re-applied for a few days at room temperature. The bias-induced damage was estimated to result in a 40–70 V addition to required bias for detectors in the ATLAS SCT after 10 years of LHC operation.     

The influence of channelling on radiation damage produced in silicon during ion bombardment

The ion bombardment of silicon results in the formation of an amorphous phase in the vicinity of the bombarded regions. This gives rise to a milky appearance which is easily distinguishable from an adjacent unbombarded region. An experiment is described which was specifically designed to study the influence of channelling of incident 80 keV Ne⁺ ions on the formation of this amorphous phase. It is found that channelling significantly reduces the rate at which this phase is produced, and in the particular case of the 110 axial channel this corresponds to a reduction in radiation damage by a factor of about 8. The results are compared with the current theories of channelling and are found to be in reasonable quantitative agreement.     

The Monte Carlo program and the pattern recognition for the microvertex detector of the E687 experiment at fnal

A Monte Carlo program and a pattern recognition have been developed in Milan to design and study the performance of microvertex detector to be used in a photoproduction experiment at the Tevatron. The aim of the experiment is the study of the heavy flavoured states (lifetimes, production mechanism, branching ratios, …). The present program has been written to simulate the photoproduction mechanism (according to the vector-meson and the photon-gluon fusion models), the tracking of the charged particles inside the detector and to study the pattern recognition performance of the whole system for various geometrical configuration of the microvertex as well as for different physical conditions.     

The forward muon detector of the DELPHI experiment at LEP

The layout and construction of the muon drift chambers equipping the end caps of the DELPHI detector are described. The performance of this forward muon detection system, determined from cosmic ray tests and data collected during the first year of LEP operation, is presented.     

Visualization of the damage evolution in impacted silicon carbide ceramics

An experimental technique has been developed by Arcueil Research and Study Center (CREA) to visualize and follow the evolution of damage in a ceramic during impact. This technique, based on the use of a high-speed camera, allows to obtain qualitative and quantitative information on the damage location and evolution. Experimental data such as crack front velocity, fracture velocity, crack density and time of damage initiation can be obtained. The advantages of this technique are discussed. The experimental set-up and the results obtained by this technique are presented. A numerical simulation is compared with experimental measurements.     

Room-temperature ultrasonic annealing of radiation defects in silicon

Room-temperature ultrasonic annealing of point radiation defects in the bulk of silicon is demonstrated for the first time. The radiation defects in single crystal silicon were generated by the exposure to γ radiation from a ⁶⁰Co source. A qualitative model of processes in the system of radiation defects under the action of ultrasound is proposed.     

Characteristics of tapped microstrip bandpass filter in BiNbO4 ceramics

The dielectric properties of BiNbO4 (BN ceramics) sintered at low temperature with CuO and V2O5 additives were determined. BN ceramics containing 0.07 wt% V2O5 and 0.03–0.05 wt% CuO sintered at 900 °C had a dielectric constant of 44.3, temperature coefficient of resonance frequency f of 2 p.p.m. °C-1 and Qxfo value of 22 000. A multilayer type band pass filter using tapped resonators and conventional resonators was designed at 1.855 GHz and PCS (personal communication system) applications. By adopting an input/output-tapping scheme the chip filter structure becomes simpler and needs fewer layers than using the conventional input/output-coupling scheme. The green ceramic sheet the for band pass filter was manufactured by a tape casting process and a multilayer type band pass filter was fabricated with a silver electrode. The simulated characteristics, including spurious resonance of the designed filters, are compared with the measured ones. The measured frequency of both exhibited similar tendencies. Even though the centered frequency was measured to shift about 90 MHz downward, the characteristics at pass band and spurious resonance characteristics were similar to that of a simulation. © 1998 Kluwer Academic Publishers     

On the generation of radiation defects by accelerated ions in silicon

The introduction of centers of generation of charge carriers in pure Si is examined in the framework of the interaction of nonequilibrium defects and charge carriers directly in the track of an ion. An experiment on a particles with energies of 1.0–5.0 MeV is supplemented by the results of a numerical simulation of the stopping of such particles in Si. It is shown that the primary defects arising at the end of the track form a smaller number of generation centers. This is explained by the trapping of components of Frenkel pairs of charge carriers, the concentration of which in the track undergoes a 3-fold increase by the end of the range. Charge exchange between vacancies and interstitial atoms both accelerates recombination and lowers the number of primary defects participating in the subsequent complex-formation. Pis’ma Zh. Tekh. Fiz. 24, 12–19 (October 26, 1998)