Design and tests of the z-coordinate drift chamber system for the opal central detector at LEP

A system of drift chambers has been designed to make high resolution measurements of the z-coordinates of charged tracks at the outer radius of the OPAL central detector at LEP. The unit module of this detector is a 25 cm drift length bidirectional cell with six sense wires in a thin 50 cm wide by 29 mm high drift slot. Tests indicate that the chamber has a wide and stable electric field operating range and its performance is unaffected by small misalignments between the drift electric field and an external magnetic field. The drift cell was found to have uniform acceptance up to its geometrical boundaries, and the z-resolution for beam tracks normal to the chamber was measured to be in the range of 40–175 μm.     

Performance of the ALEPH detector at LEP

The performance of the ALEPH detector at the LEP e⁺e⁻ collider is reviewed. The accuracy of the tracking detectors to measure the impact parameter and momentum of charged tracks is specified. Calorimeters are used to measure photons and neutral hadrons, and the accuracy obtained in energy and angle is given. An essential property of the detector is its ability to identify particles; the performance in identification of electrons, muons, neutrinos (from missing energy), charged hadrons, π⁰'s and V⁰'s is described.     

A fast trigger processor,for a scattering experiment,implemented in fastbus

A small angle interaction trigger processor (SAIT) used in a muon scattering experiment (NA28) at CERN is described. It comprises 10 FASTBUS modules and employs ECL 100K and 10K type circuits. The processor can select events with scattering angles larger than ∼1 mrad and can be used at a beam intensity of up to 10⁷ particles per second without appreciable deadtime losses.     

A fast pipelined VLSI adder for fast trigger decisions at the Superconducting Super Collider

We present a four 12-bit binary number adder proposed for use in the computation of the pipelined energy sums of data from the detectors at the Superconducting Super Collider (SSC). It was fabricated using a 1.2 μm N-well CMOS process. It comprises three 12-bit adders organized as a two-stage pipeline. To compute the final carry of each of the 12-bit adders, we used the Carry-Select technique applied to their 4-bit adder subcells. The 4-bit adders used the Carry-Lookahead method to compute their carries. In order to reduce the circuit area and to simplify the structure of this application specific integrated circuit (ASIC) we employed a Multiple-Output Domino Logic design style. The first stage of the pipeline (two adders) performs two 12-bit additions in parallel while the second stage (one adder) finishes up the previously started computation. The pipeline is driven using a two-phase clocking strategy by processing a single-phase external clock. We achieved an worst case throughput of 18 ns. In the best case the throughput was 16.5 ns. We included a built-in facility for testing the first stage of the pipeline. The area of the circuit is 1425×5510 μm², it has 76 pads, and it is packed in a 132 pin grid array (PGA). The transistor count is 6639. The dissipated power at a 18-ns clock period was ≈ 0.75 W. The circuit has been fabricated through the MOSIS service. We found an yield of ≈ 80% for a lot of 50 chips.     

The forward muon detector of the DELPHI experiment at LEP

The layout and construction of the muon drift chambers equipping the end caps of the DELPHI detector are described. The performance of this forward muon detection system, determined from cosmic ray tests and data collected during the first year of LEP operation, is presented.     

A specialized second level trigger processor

Addition to the event trigger in a conventional charged particle spectrometer of a hard-wired on-line trigger processor at second level and of a threshold Cherenkov counter at first level would enable a sensitive search for the |ΔS| = 2 weak, nonleptonic decay Ξ⁰ → pπ⁻.     

A fast programmable trigger for pattern recognition

We have built a fast programmable trigger processor based on a state-of-the-art Field Programmable Gate Array (FPGA) IC for the Palo Verde Neutrino Oscillation Experiment. The trigger processor can accommodate 160 ECL input signals, 8 NIM input signals, 16 ECL output signals and 8 NIM output signals. Our two-level trigger logic is designed asynchronously to maximize speed. We have attained trigger times of 40 ns for level 1 and 100 ns for level 2 with 132 asynchronous inputs. The trigger processor can be upgraded by replacing the FPGA with more advanced versions of the chip as they appear.     

Development of the central trigger system for the BELLE detector at the KEK B-factory

In this paper, we describe the design and development of the central trigger system (GDL) for the BELLE detector at the KEK B-factory. The GDL consists of four types of single width 6U VME modules (ITD, FTD, PSNM and TMD) which are designed using the programmable logic techniques of Xilinx FPGA and CPLD. Individual and combined performance tests of these modules are done and it is confirmed that the GDL functions as expected.     

A fast track pattern recognition

An algorithm for fast track pattern recognition is presented. Its main features are an optimized data organization and a conformal mapping to speed up fitting procedures. The code is applied to a generic collider detector. Reconstruction time, track finding efficiencies, and momentum resolution are presented.     

Fast track-finding processor based on RAM look-up table for the VENUS detector at KEK

We have developed a fast track-finding processor using signals from the central tracking chamber of the VENUS detector in the TRISTAN experiments. Particle tracks are recognized by a look-up table made with a high-speed static RAM. This method enables us to implement the track finder in the first level triggering. The track finder has been working excellently under heavy background due to synchrotron radiation. A processing time of 110 ns is attained.     

A fast and economical CAMAC front-end processor

We describe a fast and economical CAMAC auxiliary crate controller (ACC 9445) based on Fairchild's F9445 16-bit microprocessor. Design and performance as well as examples of applications are given.     

A scintillating optical fiber track imaging detector

In this paper we describe a prototype of the scintillating optical fiber isotope experiment (SOFIE) and give results of a Bevalac calibration using iron nuclei to study the measurement precision in range and trajectory which can be obtained. We have measured the range of iron nuclei with approximate energy 500 MeV/amu entering the SOFIE instrument to a precision of 200–300 μm, and their transverse position coordinate to better than 35 μm. These results indicate that scintillating optical fibers are very useful as a range detector and as a high precision hodoscope for heavy nuclei.     

A clocked,fast electronics trigger for high energy physics

For a Fermilab experiment we have designed and built gated-pulse-stretcher modules which allow us to clock all of the fast electronics with the accelerator rf, thus simplifying the trigger design.     

A fast detector for single-shot positron annihilation lifetime spectroscopy

When an intense sub-nanosecond positron pulse impinges upon a target, a pulse of γ-rays is created which can yield information concerning electron–positron pairs just prior to annihilation. Many conventional γ-ray detectors are unable to exploit the timing information contained within such pulses, and we describe here the development of a fast detector that is able to do so. Using a single-crystal PbF₂ Cherenkov radiator coupled to a fast photomultiplier tube (PMT), we have produced a detector with a time response of 4 ns (primarily determined by the PMT response), as well as a low-efficiency detector with a sub-nanosecond response. Since 511 keV photons produce very little Cherenkov light, the problem of photomultiplier saturation is mitigated and this detector is therefore well suited to single-shot positron annihilation lifetime spectroscopy (SSPALS) measurements.     

Test of a data-driven trigger processor for experiment UA8

A fast trigger, based on principles of data-driven processing, has been designed and tested for CERN SPS-Collider experiment UA8. The electronics calculates the momentum vector of a track traversing the UA8 Roman pot spectrometer in 500 ns. When imbedded in the chamber TDC readout system, the total time between signal arrival in the counting room and result is 1.2 μs. The calculations are performed by successive table look-ups and arithmetic operations executed by several examples of a single type of module configured in a data-driven architecture. The operation of the system is monitored with a package of control and diagnostic software. The trigger processor has been successfully tested at the SPS-Collider.     

A fast multianode detector for solid state ultraviolet photoelectron spectroscopy

A new angle-resolving photoelectron spectrometer has been developed which uses a fast multianode parallel readout. The detector has been designed for high resolution ultraviolet photoelectron spectroscopy from solid surfaces using synchrotron radiation. Examples of initial results obtained with the detector using a rare gas discharge lamp are presented.     

A fast and versatile wire chamber space point finding processor

A four plane, four metre square, multiwire proportional counter at the CERN Omega spectrometer is used to digitize the spatial position of charged particles and generate a fast second level trigger. The coordinates of cluster centroids are fed into a modular space point finding processor which can analyse a ten particle event in 40 μs.The detector and the algorithms are described in the first part of this paper, the hardware implementation and the performance are then discussed.     

Efficiency of Billoir's track fitting method for the OPAL central detector

Track fitting in the OPAL central detector can be improved at low energies with a recursive method due to Billoir [1], which accounts for multiple scattering.