P. Abbon

The Micromegas detector of the CAST experiment

A low-background Micromegas detector has been operating in the CAST experiment at CERN for the search for solar axions during the first phase of the experiment (2002?2004). The detector, made out of low radioactivity materials, operated efficiently and achieved a very high level of background rejection (5 ? 10?5 counts keV?1?cm?2?s?1) without shielding.

Micromegas as a large microstrip detector for the COMPASS experiment

Abstract Recent results on the gaseous microstrip detector Micromegas which will be used to track particles in the COMPASS experiment at CERN are presented. Developments concerning its mechanical and electrical design, associated readout electronics and gas mixture were carried out. Particular attention was paid to the discharge phenomenon which affects this type of microstrip detector. The adequacy of the options finally retained, especially the SFE16 readout and the use of a Ne–C 2 H 6 –CF 4 gas mixture, was demonstrated in a set of beam tests performed on a 26×36 cm 2 prototype. Operating at a gain of ∼6400, full efficiency is reached along with a spatial resolution of ∼50 μm and a timing accuracy of 8.5 ns . Discharges are kept at a low rate, less than one per SPS spill in a COMPASS-like environment. Via a decoupling of the strips through individual capacitors their impact is greatly reduced. They generate a dead time on the full detector of ∼ 3 ms , affecting marginally the detection efficiency given their rate. The probability of discharge, at a given value of efficiency, is found to decrease with the mean value of the gas mixture atomic number. In view of these results, the commissioning of Micromegas for COMPASS is foreseen in the near future.

SFE16, a low noise front-end integrated circuit dedicated to the read-out of large Micromegas detectors

A front-end BiCMOS ASIC was specially developed for the Micromegas detectors to be used in the Small Angle Tracker of the COMPASS experiment at CERN. Each of the 16 channels of this integrated circuit contains a low noise preamplifier with a 100 ns peaking time filter and a discriminator driving a low-level differential digital buffer. The design of the preamplifier and the choice of the shaping have been tuned to the detector signal shape in order to allow the operation of Micromegas even for very low multiplication gain values. Noise measurements show an equivalent noise charge of less than 1500 e-rms for a detector capacitance of 40 pF. The measured performances of this ASIC associated or not with the detector are fully described in this paper.

DMILL, a mixed analog-digital radiation-hard BICMOS technology for high energy physics electronics

High energy physics experiments under preparation at CERN (Geneva, Switzerland) with the future LHC (Large Hadron Collider) require a fast, low noise, very rad-hard, mixed analog-digital microelectronics VLSI technology. Readout electronics designed using such a technology for the central parts of the LHC particle detectors must withstand more than 10 Mrad (SiO/sub 2/) and 10/sup 14/ neutrons/cm/sup 2/ over 10 years of operation. We are presenting here recent results obtained with a new rad-hard analog-digital technology called DMILL, which monolithically integrates NPN bipolar, CMOS and P-JFET transistors, and which has been specifically developed to fulfil the severe constraints of LHC detectors readout circuits.

The gaseous microstrip detector micromegas for the COMPASS experiment at CERN

Abstract The measurements foreseen 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, have been operated with success in the summer of 2002 in the COMPASS environment. We describe here the performances and results obtained.

Fast photon detection for particle identification with COMPASS RICH-1

Particle identification at high rates is an important challenge for many current and future high-energy physics experiments. The upgrade of the COMPASS RICH-1 detector requires a new technique for Cherenkov photon detection at count rates of several

Pattern recognition and PID for COMPASS RICH-1

10^6

Industrial transfer and stabilization of a CMOS-JFET-bipolar radiation-hard analog-digital SOI technology

per channel in the central detector region, and a read-out system allowing for trigger rates of up to 100 kHz. To cope with these requirements, the photon detectors in the central region have been replaced with the detection system described in this paper. In the peripheral regions, the existing multi-wire proportional chambers with CsI photocathode are now read out via a new system employing APV pre-amplifiers and flash ADC chips. The new detection system consists of multi-anode photomultiplier tubes (MAPMT) and fast read-out electronics based on the MAD4 discriminator and the F1-TDC chip. The RICH-1 is in operation in its upgraded version for the 2006 CERN SPS run. We present the photon detection design, constructive aspects and the first Cherenkov light in the detector.

The fast readout system for the MAPMTs of COMPASS RICH-1

Abstract A package for pattern recognition and PID by COMPASS RICH-1 has been developed and used for the analysis of COMPASS data collected in the years 2002–2004, and 2006–2007 with the upgraded RICH-1 photon detectors. It has allowed the full characterization of the detector in the starting version and in the upgraded one as well as the PID for physics results. We report about the package structure and algorithms, and the detector characterization and PID results.

Micromegas: Large-Size High-Rate Trackers in the High Energy Experiment COMPASS

DMILL technology integrates mixed analog-digital very rad-hard (>10 Mrad and >10/sup 14/ neutron/cm/sup 2/) vertical bipolar, 0.8 /spl mu/m CMOS and 1.2 /spl mu/m PJFET transistors on SOI substrate. In this paper, after a presentation of the DMILL program goal, we discuss more into details the main technological choices, the main milestones from the R&D to the industrial implementation, and the main results obtained after stabilization of the final process-flow in the MHS foundry.