J. Oliver

ATLAS Muon Drift Tube Electronics

This paper describes the electronics used for the ATLAS monitored drift tube (MDT) chambers. These chambers are the main component of the precision tracking system in the ATLAS muon spectrometer. The MDT detector system consists of 1,150 chambers containing a total of 354,000 drift tubes. It is capable of measuring the sagitta o f muon tracks to an accuracy of 60 μm, which corresponds to a momentum accuracy of about 10% at pT = 1 TeV. The design and perfor- mance of the MDT readout electronics as well as the electronics for controlling, monitoring and powering the detector will be discussed. These electronics have been extensively tested under sim- ulated running conditions and have undergone radiation testing certifying them for more than 10 years of LHC operation. They are now installed on the ATLAS detector and are operating during cosmic ray commissioning runs.

On-chamber readout system for the ATLAS MDT muon spectrometer

The ATLAS MDT Muon Spectrometer is a system of approximately 380 000 pressurized cylindrical drift tubes of 3 cm diameter and up to 6 m in length. These monitored drift tubes (MDTs) are precision glued to form superlayers, which in turn are assembled into precision chambers of up to 432 tubes each. Each chamber is equipped with a set of mezzanine cards containing analog and digital readout circuitry sufficient to read out 24 MDTs per card. Up to 18 of these cards are connected to an on-chamber DAQ element referred to as a chamber service module (CSM). The CSM multiplexes data from the mezzanine cards and outputs this data on an optical fiber which is received by the off-chamber DAQ system. Thus, the chamber forms a highly self-contained unit with DC power in and a single optical fiber out. The MDTs, due to their length, require a terminating resistor at their far end to prevent reflections. The readout system has been designed so that thermal noise from this resistor remains the dominant noise source of the system. This level of noise performance has been achieved and maintained in large scale on-chamber tests.

Design, performance and status of the CLEO III silicon detector

Abstract The CLEO III silicon detector is part of a general upgrade of the CLEO detector to allow for operation at a luminosity of 2×10 33 cm −2 s −1 , which will be provided by the Cornell Electron–Positron Storage Ring (CESR) beginning in 1999. The silicon detector is a four-layer barrel design covering radii from 2.5 to 10.2 cm with 93% solid angle coverage. The silicon sensors are DC-coupled and double-sided with double-metal readout on the p-side. The n-type strips measure φ , with 50 μ m pitch while the p-type strips measure z , the coordinate along the beam axis, with 100 μ m pitch. The readout electronics are mounted on BeO hybrids attached to the conical support structure and connected to the silicon sensors via a thin kapton flex cable. The electronics consist of an R / C chip with bias resistors and decoupling capacitors, a low-noise preamp/shaper chip and a digitizer/sparsifier chip. Readout is done using VME-based sequencer boards. Production of all detector components is nearing completion and installation of the detector will take place in early 1999.

STUDY OF SILICON THICKNESS OPTIMIZATION FOR LSST.

Sensors for the LSST camera require high quantum efficiency (QE) extending into the near-infrared. A relatively large thickness of silicon is needed to achieve this extended red response. However, thick sensors degrade the point spread function (PSF) due to diffusion and to the divergence of the fast f/1.25 beam. In this study we examine the tradeoff of QE and PSF as a function of thickness, wavelength, temperature, and applied electric field for fully-depleted sensors. In addition we show that for weakly absorbed long-wavelength light, optimum focus is achieved when the beam waist is positioned slightly inside the silicon.

THE CLEO III SILICON TRACKER

Abstract The Cornell Electron Storage Ring is being upgraded to B-factory luminosities. The CLEO detector is also being upgraded with a new charged particle tracking system and with the addition of a ring imaging Cerenkov particle identification system. A major part of the tracking system upgrade is the construction of a new four-layer double-sided silicon tracker with 93% solid angle coverage and new readout electronics. The status of the silicon tracker including production tests and the expected performance of the final system are discussed.

A method to quench and recharge avalanche photo diodes for use in high rate situations

Abstract We present a new method of using avalanche photo diodes (APDs) for low level light detection in Geiger mode in high rate situations such as those encountered at the Superconducting Super Collider (SSC). The new technique is readily adaptable to implementation in CMOS VLSI.

The LSST sensor technologies studies

The LSST project has embarked on an aggressive new program to develop the next generation of silicon imagers for the visible and near-IR spectral regions. In order to better understand and solve some of the technology issues prior to development and mass-production for the huge LSST focal plane, a number of contracts have been written to imager firms to explore specific areas of technology uncertainty. We expect that these study contracts will do much toward reducing risk and uncertainty going into the next phase of development, the prototype production of the final large LSST imager.

Design and initial performance of the CLEO III silicon tracker

Abstract CLEO III is the new experimental phase of the CLEO experiment at the CESR accelerator. Both the accelerator and the detector have recently been upgraded. A new charged particle tracking system with the addition of a ring imaging Cherenkov particle identification system has been installed. A major part of the tracking system upgrade was the construction of a new four-layer double-sided silicon tracker with 93% solid angle coverage and new readout electronics. The CLEO III upgrade was completed in February 2000 with the installation of the silicon detector. CLEO III has finished the commissioning phase and is now taking data. The design of the detector and first performance results are presented here.

Low noise electronics for the CLEO III silicon detector

Abstract We report here the status of the CLEO III silicon vertex detector electronics. The CLEO III silicon detector is a 4-layer barrel-style device which spans 93% of the solid angle observing the interaction region. All layers will be constructed with double-sided silicon. The innermost layer must be able to handle large singles rates associated with a detector situated near the interaction region. In order to cover the required solid angle, the outermost layer is 55 cm long and presents a large capacitive load to the front-end electronics. The electronics chain chosen to meet this challenge consists of a low noise cascode preamplifier followed by an ADC on each channel. The system issues will be described herein together with the chosen solutions, noise performance of each subsystem prototype, and expected results of the full system.

An electromagnetic calorimeter for the small angle regions of the collider detector at Fermilab

Abstract Two large electromagnetic calorimeters have been built for the Collider Detector at Fermilab (CDF). These have been designed for use in the small angle regions in both the proton and the antiproton beam directions. Each calorimeter consists of 30 sampling layers of proportional tube chambers with cathode pad readout separated by lead sheets for a total thickness of 25.5 radiation lengths. Each proportional tube chamber is constructed using a novel technique in which the insulating side of the cathode pad board is bonded to the proportional tube walls using resistive epoxy. The measured energy response of the calorimeter is linear up to 160 GeV, and the measured energy resolution, σ E E , is approximately 25% √E + 0.5% . The position resolution for single electrons varies between 1 and 4 mm depending on location in the calorimeter. The calorimeter offers good e π discrimination, where typically the pion misidentification probability ƒ π → e for an electron identification efficiency ϵ90%.