J. Fent

Initial tests of a high resolution Scintillating Fibre (SCIFI) tracker

Abstract We present our initial measurements of high resolution particle tracking in scintillating fibre (SCIFI) detectors. The scintillator under study is a glass, designated GS1, which is doped with the cerium (Ce 3+ ) emitter. We conclude from our measurements that present SCIFI detectors can be successfully used as small-volume “active” targets, but that further developments are necessary before this technique can be applied to high precision tracking in collider detectors.

Realization of a second level neural network trigger for the H1 experiment at HERA

Abstract Since 1996 the H1 experiment is fully equipped with two independent fast pattern recognition systems operating as second level triggers (L2). The decision time is 20 μs. One of the two is the neural network trigger. It runs an array of presently ten VME-boards with CNAPS 1064 chips (20 MHz, 128 Mcps) by Adaptive Solutions. The input trigger data from the detector components arrive in various formats on a 8 × 16 bit wide 10 MHz bus. Before usable as 8-bit input values to the CNAPS they are preprocessed by several bit-manipulating algorithms and arithmetic functions implemented on XILINX 4008 field programmable gate arrays (FPGA). The startup strategy for the new system is to concentrate on photoproduction channels or low multiplicity final states which so far could only be efficiently triggered with unacceptable high rates.

The ALEPH minivertex detector

Abstract Vertex detectors allow high precision reconstruction of particle tracks and therefore make possible the investigation of the decay topology of short-lived particles in collider experiments. In the ALEPH experiment at LEP a minivertex detector will be installed. It consists of silicon microstrip detectors arranged on two concentric “cylindrical” surfaces around the interaction point. With this geometry it will be possible to measure the r − ϕ − z coordinates of particles traversing the detector. The expected position resolution is 10 μm in r − ϕ and 20 μm in r − z . For optimum signal processing monolithic CMOS readout electronics are under development. Each chip consists of 60 charge sensitive preamplifiers, multiplexed into one output channel. Fast power switching will reduce heat dissipation. Details about construction and expected device performance will be described.

Radiation qualification of the front-end electronics for the readout of the ATLAS liquid argon calorimeters

The ATLAS detector has been built to study the reactions produced by the Large Hadron Collider (LHC). ATLAS includes a system of liquid argon calorimeters for energy measurements. The electronics for amplifying, shaping, sampling, pipelining, and digitizing the calorimeter signals is implemented on a set of front-end electronic boards. The front-end boards are installed in crates mounted between the calorimeters, where they will be subjected to significant levels of radiation during LHC operation. As a result, all components used on the front-end boards had to be subjected to an extensive set of radiation qualification tests. This paper describes radiation-tolerant designs, radiation testing, and radiation qualification of the front-end readout system for the ATLAS liquid argon calorimeters.

Electron identification with a prototype of the Transition Radiation Tracker for the ATLAS experiment: ATLAS TRT collaboration

Abstract A prototype of the Transition Radiation Tracker (TRT) for the ATLAS detector at the LHC has been built and tested. The TRT is an array of straw tubes which integrate tracking and electron identification by transition radiation into one device. Results of experimental measurements and of comparisons with Monte-Carlo simulations are presented for the electron identification performance as a function of various detector parameters. Under optimal operating conditions, a rejection against pions of a factor 100 was achieved with 90% electron efficiency.

A high resolution scintillating fibre (SCIFI) tracking device with CCD readout

Abstract We present our initial test beam measurements of a high resolution scintillating fibre (SCIFI) detector with charge coupled device (CCD) readout. We discuss the analysis procedure and evaluate the performance of the detector and its readout assembly. We find a detected photon density along minimum ionising tracks of 2.0 mm −1 , with a straight-line rms residual of (19.3 ± 2.9) μm , giving rise to a track impact parameter precision of (8.8 ± 2.0) μm . The two-track resolution is found to be 52 μm.

A CMOS readout system for very large detector capacitances

Abstract In this contribution we present readout electronics for a liquid-argon calorimeter. It has been designed and optimized for operation at cryogenic temperatures and it is integrated in an n-well 2 μm CMOS technology. The chip contains 16 analog channels with switched-capacitor circuits for charge collection, storage, and amplification, and averaging and correlated double sampling circuits for noise reduction. Further components include a trigger generator, an analog multiplexer, digital control circuits for analog switching, and 50 ω cable drivers.

Study of a novel electromagnetic liquid argon calorimeter — the TGT

Abstract The concept and the basic design of a fast, highly granular and compact electromagnetic liquid argon calorimeter are described. This novel calorimeter offers uniform energy response and constant energy resolution independent of the production angle of an impinging particle and of its impact position at the calorimeter. An example of a calorimeter with full rapidity coverage in an application in a collider detector is given. An important aspect of the concept is the electronics for fast signal processing matched to the short charge collection time. We report on the experience with the realization of a prototype calorimeter module and on its performance in a testbeam exposure.

Artificial Neural Networks as a Level-2 Trigger for the H1 Experiment: Status of the Hardware Implementation

Triggering at the HERA ep collider is challenging because of the high bunch crossing rate and an expected large background. In the H1 experiment, a trigger decision is made in four steps (level 1–4), stepwise decreasing the event rate and allowing for more sophisticated trigger decisions. The time available for L2 is about 20 μs. We have proposed to use an artificial neural network (ANN) for the L2 trigger based on the CNAPS-1064 chip available from Adaptive Solutions, (Oregon, USA). The intrinsic parallelism of the ANN algorithm together with the dedicated hardware offers fast processing of the trigger informations. The trigger system uses up to 10 decision units, each consisting of a Pattern Recognition Module (PRM) and a Data Distribution Board (DDB). A DDB receives the L2 data stream and generates the network inputs used by the algorithms on the PRM. A PRM is a commercial VME board carrying the CNAPS processors.

Cold electronics for the liquid argon hadronic endcap calorimeter of ATLAS

This paper describes the on-detector electronics of the ATLAS hadronic end-cap calorimeter (HEC). The electronics is working in liquid argon; therefore the attention is paid to its performance at low temperatures. The calibration and signal cables have been studied in laboratory conditions and signal distortion is modeled. The core of the electronics are GaAs preamplifiers. We present the design, layout and measured characteristics of preamplifier chips and summing boards. The on-module signal distribution is also described. All parts of the electronics have been produced, tested and assembled on the calorimeter modules. The summary of commissioning tests is presented.