P. Cattaneo

The MPI/AIT X-ray imager (MAXI) — High speed pn CCDs for X-ray detection

MAXI (MPI/AIT X-ray Imager) is part of a proposal submitted to the European Space Agency (ESA) as focal plane instrumentation of the X-ray Multi Mirror Mission (XMM). Within a collaboration of 13 European institutes we have proposed a fully depleted (sensitive) pn CCD of 280 μm thickness with a homogeneous sensitive area of 36 cm2 and a pixel size of 150×150 μm2 which is well matched with the telescopes angular resolution of 30 arcsec translating to a position resolution of approximately 1 mm in the focal plane. The X-ray sensitivity will be higher than 90% from 250 eV up to 10 keV, the readout time in the full frame mode of the complete focal plane will be 2 ms with a readout noise of better than 5 e− (rms). Prototypes of all individual components of the camera system have been fabricated and tested. The camera concept will be presented. The measured transfer properties of the CCD and the on-chip electronics will be treated. Taking into account the coupling of the on-chip amplifier to the following front-end electronics the expected performance will be derived.

The design, construction and performance of the ALEPH silicon vertex detector

Abstract The ALEPH silicon vertex detector is the first detector operating in a colliding beam environment that uses silicon strip detectors which provide readout on both sides and hence a three-dimensional point measurement for the trajectory of charged particles. The detector system was commissioned successfully at the e+e− collider LEP at the research centre CERN, Switzerland, during the year 1991 while taking data at the Z0 resonance. The achieved spatial resolution of the complete 73 728 channel device (intrinsic plus alignment) is 12 μm in the r-f view and 12 μm in the z view. The design and construction of the entire detector system are discussed in detail and the experience gained in running the detector will be described with special emphasis on the uses of this novel tracking device for the physics of short-lived heavy particles produced in the decays of the Z0 resonance.

Capacitance calculation in a microstrip detector and its applications to signal processing

Abstract A detailed knowledge of the capacitances inside a microstrip detector is important to a full understanding of its physics. Several methods mainly based on the conformal transformation method are exploited to obtain results at different levels of approximation. The results so obtained are then used to build a circuital model of a microstrip detector that supplies the relevant values for the treatment of both noise and signal.

Operational experience with a large detector system using silicon strip detectors with double sided readout

Abstract A large system of silicon strip detectors with double sided readout has been successfully commissioned over the course of the last year at the e + e − collider LEP. The readout of this 73 728 channel system is performed with custom designed VLSI charge sensitive amplifier chips (CAMEX64A). An overall point resolution of 12 μm on both sides has been acheived for the complete system. The most important difficulties during the run were beam losses into the detector, and a chemical agent deposited onto the electronics; however, the damage from these sources was understood and brought under control. This and other results of the 1991 data-taking run are described with special emphasis on the operational experience.

New developments in double sided silicon strip detectors

A new type of double-sided silicon strip detector has been built and tested using high-density VLSI readout electronics connected to both sides. Capacitive coupling of the strips to the readout electronics has been achieved by integrating the capacitors into the detector design, which was made possible by introducing a new detector biasing concept. Schemes to simplify the technology of the fabrication of the detectors are discussed. The static performance properties of the devices as well as implications of the sue of VLSI electronics in their readout are described. Prototype detectors of the described design equipped with high-density readout electronics have been installed in the ALEPH detector at LEP (Large Electron Positron Collider). Test results on the performance are given. >

Calibration procedure for irradiation tests on silicon devices

The problems of dosimetry encountered during irradiation tests on silicon devices using different radiation sources are discussed. The use of the p-i-n diode BPW 34 from Siemens as a calibration device is described. Its response and limitations at different radiation environments, bias voltages, and integrated absorbed doses are discussed. The experimental results on the dependence of the photocurrent on the bias voltage fitted with theoretical expectations. >

Radiation hardness tests on the read out electronics chain of the ALEPH minivertex detector

Abstract In ALEPH a double sided microstrip detector has been installed as minivertex detector. Its read out electronics consists of a custom designed VLSI amplifier CAMEX 64, a digital steering chip running the CAMEX and a line driver driving the output line. All these components have been subjected to extensive tests of radiation hardness in different radiation environments and bias conditions. Both noise increase, modification of the working parameters and sudden breakdown have been observed. The CAMEX 64 under bias condition stands only up to 20–30 krad and hence is the weakest point of the chain.