on CMS information server CMS NOTE 1997 / 061 The Compact Muon Solenoid Experiment
The high radiation environment at the LHC will require the use of radiation hardened microelectronics for the readout of inner detectors. Two such technologies are a Harris bulk CMOS process and the DMILL mixed technology process. Transistors have been fabricated in both of these and have been tested before and after irradiation to 10 Mrads, the total dose expected in the innermost silicon microstrip layers. Several processing runs of Harris transistors have been carried out and samples from one have also been irradiated to 100 Mrads. A preamplifier-shaper circuit, to be used for readout of the CMS microstrip tracker, has been tested and the noise performance is compared with individual transistors.
Radiation Environment Simulations for the CMS Detector
This paper provides an overview of the most important radiation issues at the CMS experiment at LHC and gives a review of the simulations performed and the main results obtained with the FLUKA code during the last three years. The main emphasis is put on recent results, reported in the CMS Technical Proposal or those obtained thereafter. It is shown that for most of the CMS subdetectors proper radiation shielding is vital in order to guarantee a reliable operation and sufficient life span of the detectors. In addition new results on induced activity are presented.
The deconvolution method of fast pulse shaping at hadron colliders
Abstract We describe a new technique for front-end signal processing of signals from LHC or SSC detectors which precisely defines the origin of an event in time while maintaining amplitude measurement with an excellent signal to noise ratio. The method is designed for use with silicon detectors whose leakage currents may be substantially increased during the lifetime of an experiment by radiation damage, although it is likely to be applicable to other types of detector. It makes use of a shaping amplifier with a time constant of several beam crossing intervals and is particularlt well matched to CMOS front ends where low power consumption and low noise is best achieved by utilising pulse shapes with time constants ∼50 ns. It is based on discrete time filtering of data extracted from an analogue pipeline after a first level trigger. A finite impulse response type filter deconvolutes the sampled voltages of a shaped pulse to retrieve the original impulse signal with high precision. We describe the mathematical basis of the technique and its implications for timing and signal to noise. Measurements have been made on a CMOS amplifier intended as a prototype for readout of silicon microstrip detectors at LHC which demonstrates the power of this approach. A CMOS circuit emulating the filter is being built. It has been implemented with extremely low power consumption (