S. Berglund

The ATLAS Tile Calorimeter Digitizer

The ATLAS Tile Calorimeter digitizer system samples photomultiplier signals from the scintillating tiles of the hadronic calorimeter. For each channel a pair of 10-bit ADCs digitize high and low gain signals at 40.08 MHz to provide the necessary 16-bit dynamic range. The sampled data is temporarily stored in digital pipelines for up to 6.375 ms, awaiting a level-1 accept. For each accept received, the corresponding sampled pulse is transferred to a derandomizer buffer for subsequent readout to the data acquisition system (DAQ).

Temperature dependence of CsI(Tl) scintillation yield for cosmic muons, 5 and 1.25 MeV γ-rays

Abstract We have measured the temperature dependence of the CsI(Tl) light yield with photodiode readout over the temperature range −90 to −40°C for three excitation sources: cosmic muons, 5 MeV γ-rays from a Pu-C source and 1.25 MeV γ-rays from a 60 Co source. The temperature dependence does not vary with the excitation source but is somewhat steeper than reported in previous measurements. The results are discussed with application to using CsI(Tl) in high altitude experiments.

FERMI: a digital Front End and Readout MIcrosystem for high resolution calorimetry

We present a digital solution for the front-end electronics of high resolution calorimeters at future colliders. It is based on analogue signal compression, high speed A/D converters, a fully programmable pipeline and a digital signal processing (DSP) chain with local intelligence and system supervision. This digital solution is aimed at providing maximal front-end processing power by performing waveform analysis using DSP methods. For the system integration of the multichannel device a multi-chip, silicon-on-silicon multi-chip module (MCM) has been adopted. This solution allows a high level of integration of complex analogue and digital functions, with excellent flexibility in mixing technologies for the different functional blocks. This type of multichip integration provides a high degree of reliability and programmability at both the function and the system level, with the additional possibility of customising the microsystem to detector-specific requirements. For enhanced reliability in high radiation environments, fault tolerance strategies, i.e. redundancy, reconfigurability, majority voting and coding for error detection and correction, are integrated into the design. (Less)

A digital front-end and readout microsystem for calorimetry at LHC

Abstract A digital solution to the front-end electronics for calorimetric detectors at future supercolliders is presented. The solution is based on high speed A D converters, a fully programmable pipeline/digital filter chain and local intelligence. Questions of error correction, fault-tolerance and system redundancy are also being considered. A system integration of a multichannel device in a multichip, Silicon-on-Silicon Microsystem hybrid, is used. This solution allows a new level of integration of complex analogue and digital functions, with an excellent flexibility in mixing technologies for the different functional blocks. It also allows a high degree of programmability at both the function and the system level, and offers the possibility of customising the microsystem with detector-specific functions.

The ATLAS tile calorimeter digitizer

We describe a readout system designed to serve the 9728 PMT channels of the ATLAS Tile calorimeter at LHC. The system will be located immediately outside the calorimeter with limited accessibility and moderate radiation levels, making reliability an important issue in the design. Six or eight boards per calorimeter module each receive and digitize high and low gain signals from six PMTs every 25 ns. Two custom designed gate arrays on each board store the data in digital pipelines until validated by the first level trigger. Selected data are formatted and read out for use by the DAQ and second level trigger systems. Configuration and control commands are distributed to the digitizer boards via the TTC clock distribution system. The current digitizer design was developed for test beam tests during summer 1999, and the final system is scheduled for volume production in the beginning of 2000.

Optimized digital feature extraction in the FERMI microsystem

Abstract We describe the digital filter section of the FERMI readout microsystem. The filter section, consisting of two separate filter blocks, extracts the pulse amplitude and time information for the first-level trigger process and performs a highly accurate energy measurement for higher-level triggering and data readout purposes. An FIR-order statistic hybrid filter structure is used to improve the amplitude extraction performance. Using a training procedure the filters are optimized to produce a precise and accurate output in the presence of electronics and pile-up noise, sample timing jitter and the superposition of high-energy pulses. As the FERMI system resides inside the detector where accessibility is limited, the filter implementations are presented together with fault tolerance considerations. The filter section is modelled with the VHDL hardware descriptive language and the subsystems are further optimized to minimize the system latency and circuit area.

System level policies for fault tolerance issues in the FERMI project

The FERMI system, performing acquisition and DSP of calorimeter data in high energy collision experiments, planned at the LHC collider (CERN, Geneva, CH) is briefly overviewed. The system relies mainly upon the FERMI module, a dedicated VLSI multichip device performing most of the above functions, which is to be installed in large quantities (around 10/sup 5/) in the immediate neighborhood of the collider itself, requiring rad-hard features. The issues for a system which absolutely requires fault diagnosis and possibly fault tolerance are described, with regard to the FERMI module itself.

A Spaceborne CsI(T1) Calorimeter For Cosmic Gamma Rays

Features of an instrument capable of measuring accurately cosmic gamma rays in the gigaelectronvolt energy range are discussed. The main component of this instrument is an electromagnetic calorimeter based on rods of CsI(Tl). The expected energy resolution is about 1% at 3 GeV. The use of such a calorimeter in a spaceborne experiment poses some technical problems. The temperature variation of the scintillation light yield must be accurately known in order to correct the data. The temperature dependence using cosmic ray muons and various radioactive sources is reported. The calibration of individual rods is crucial to achieving the desired resolution. Various methods of performing calibration in space, such as radioactive sources and cosmic rays, are discussed and it is concluded that a calibration procedure utilizing cosmic rays is feasible. Space experiments require stable low-power electronics. Readout electronics are presented, and estimates of noise and rates are given. >

Functional irradiation tests of the Atlas TileCal Digitizer using FPGA testbenches

The new LHC particle accelerator now being built at CERN will have a radically increased event rate and higher energy. To accommodate this, instrumentation for LHC experiments has had to be constructed using new ideas and the latest available technology. A part of this effort was the development and test of a digitizer unit for the hadron calorimeter (TileCal) of the ATLAS experiment. To try out ideas and promote system integration, prototypes were tested in a subsystem using a particle beam to simulate the final conditions. During the development of these prototypes an application-specific integrated circuit was constructed to control the digitizer system. Tests made at the test beam facility have verified that all requirements were met. The final digitizer design and its components were radiation tested to verify full functionallity in its radiation environment during the full ATLAS life-span. Test devices were also constructed to test all production units. In addition to the digitizer system, an optical readout link was designed to meet the requirements for the digitizer readout. Preliminary studies indicate that the digitizer could also be used in an upgraded LHC, with presently considered scenarios.

Production and Test of the ATLAS Hadronic Calorimeter Digitizer

The new LHC particle accelerator now being built at CERN will have a radically increased event rate and higher energy. To accommodate this, instrumentation for LHC experiments has had to be constructed using new ideas and the latest available technology. A part of this effort was the development and test of a digitizer unit for the hadron calorimeter (TileCal) of the ATLAS experiment. To try out ideas and promote system integration, prototypes were tested in a subsystem using a particle beam to simulate the final conditions. During the development of these prototypes an application-specific integrated circuit was constructed to control the digitizer system. Tests made at the test beam facility have verified that all requirements were met. The final digitizer design and its components were radiation tested to verify full functionallity in its radiation environment during the full ATLAS life-span. Test devices were also constructed to test all production units. In addition to the digitizer system, an optical readout link was designed to meet the requirements for the digitizer readout. Preliminary studies indicate that the digitizer could also be used in an upgraded LHC, with presently considered scenarios.