Electron Test Beam Research Articles

High-rate particle triggering with triple-GEM detector

We report the results of a systematic study of the time performance of triple-GEM detectors operated with Ar/CO 2/CF 4 and Ar/CF 4/iso-C 4H 10 gas mixtures. This study and the detector development has been performed in the framework of an R&D activity on detectors for the innermost part (region R1) of the first muon station (M1) of the LHCb experiment. The use of fast gas mixtures allows to achieve a time resolution better than 5 ns (r.m.s.) and a single detector efficiency up to ∼ 99% in a 20 ns time window. Discharge studies have been performed at the πM1 hadron beam facility of the Paul Scherrer Institute. Local aging properties were investigated exposing the detector to a collimated 5.9 keV X-rays beam. The whole R&D activity with different gas mixtures has been performed with small 10×10 cm 2 triple-GEM detector prototypes. A full size prototype (module-0) constituted by two 20×24 cm 2 triple-GEM detectors, equipped with front-end electronics based on ASDQ chip, has been built and successfully tested, with the chosen Ar/CO 2/CF 4=45/15/40 gas mixture, at the electron test beam facility at the Laboratori Nazionali di Frascati.

An Electromagnetic Calorimeter with a Transversal Orientation of the Scintillating Fibers

The space and energy resolutions of the SPACAL electromagnetic calorimeter with a transverse orientation of the scintillating fibers have been measured. The main parameters of the calorimeter are presented. The results of experiments with an electron test beam of the DESY synchrotron at energies E = 1–6 GeV are discussed. The measured energy resolution of the calorimeter is found to be (σ/E) = 12.7%/√E ⊕ 2.0% (E is expressed in terms of GeV), and the space resolution is σx, y(E) = 1 mm at E = 4 GeV.

The luminosity monitor of the HERMES experiment at DESY

A detector is described which measures the luminosity of the HERMES experiment at DESY. It is based on the coincident detection of electron–positron and photon pairs, or electron pairs, originating from the interaction of the beam positrons, or electrons, with the electrons of the atomic gas target. It consists of two calorimeters with radiation hard NaBi(WO 4) 2 crystals. Properties of the monitor, investigated in an electron test beam, and its performance in the experiment are presented.

Aging measurements of a TMAE based photon detector for the HERA-B RICH

We report on aging measurements of a photon detector candidate, based on proportional wire chambers operating in TMAE, for the HERA-B RICH. The detector consisted of 64 cells, each 100 mm long and 8×8 mm 2 in area, constructed with brass cathode and 45 μm gold plated tungsten anode wire and was operated at room temperature with 50% TMAE saturated methane. To age the chamber it was exposed for several weeks to UV light from a deuterium lamp at 3 MHz/cm 2 counting rate, the expected maximum rate in the HERA-B RICH. The detection efficiency of the chamber for Cherenkov photons, generated in 5 m of argon by a 3 GeV electron testbeam at DESY, was recorded at regular intervals during the aging process. The pulse-height distribution of the chamber was continuously monitored. We found significant chamber gain loss after an exposure equivalent to about one month of running at HERA-B. Based on our results HERA-B decided to employ a multi-anode PMT system as photon detector in the RICH.

Electron testbeam results for the ATLAS liquid argon forward calorimeter prototype

A novel liquid argon calorimeter concept with thin cylindrical shell gaps, meeting the required physics performance for the forward region (/ vbη/ vb > 3) in a high energy, high luminosity hadron collider experiment such as ATLAS, is described. A prototype for the electromagnetic section was built and tested in two electron testbeam runs at the Brookhaven AGS and at the CERN North Area in 1993, covering a total energy range from 2 to 200 GeV. Dependences of the signal on the impact angle and varying inactive material in front of the calorimeter have been studied. Important performance requirements such as signal linearity better than 2%, a sufficient energy resolution with a constant term of about 4% and a very good space resolution of about 0.6 mm have been demonstrated.

Test beam results for an upgraded forward tagger of the L3 experiment at LEP II

We have tested new scintillator modules with silicon photodiode readout for the upgraded Active Lead Rings (ALR) of the L3 detector at LEP II. Results are presented from data recorded in muon and electron test beams with particular emphasis on the light production and collection as a function of the particle impact position on the scintillator modules. The results from the beam test data will be used for the design of the readout and trigger electronics in conjunction with the required ALR performance as an electron tagger and beam background monitor at LEP II.

Beam test of radiation hardness of a scintillating tile/fiber calorimeter

Radiation hardness of a scintillating tile/fiber calorimeter is studied by irradiating electromagnetic test modules with 2.5 GeV electrons at the KEK linac. The induced damage is evaluated in a 2 GeV electron test beam by measuring the reduction in pulse height after irradiation. The pulse height peak for 2 GeV electrons is found to decrease by 19.3 ± 1.3% for a dose of 0.61 Mrad and 14.9 ± 2.7% for 0.33 Mrad. In addition to these modules, several tile/fiber assemblies were irradiated up to 4.8 Mrad and the damage as a function of dose was measured with a radioactive source. Effects of radiation damage on the linearity and energy resolution at higher energies are evaluated using a GEANT simulation and the measured damage.

The electromagnetic calorimeter in the hyperon beam experiment at CERN

An electromagnetic calorimeter has been built for the hyperon beam experiment WA89 at CERN. It is composed of 642 lead glass Cherenkov counters. The detector was calibrated with an electron test beam and with an extensive π0 sample produced in hyperon beam runs. The setup, the performance and results from operation in WA89 are presented.

Calibration and validation of a time of flight detector

The time of flight detector of the E665 experiment at Fermilab is continuously checked and calibrated. The use of a laser calibration system enables the synchronization of individual counters and allows the correction of time shifts caused by systematic effects. With an electron test beam an average overall time resolution of 225 ps was measured.

Construction and performance of a position detector for the UA1 uranium-TMP calorimeter

A full-scale prototype position detector has been built and tested for the uranium-tetramethylpentane (TMP) calorimeter which is presently being constructed for the UA1 experiment at the CERN proton-antiproton collider. The position detector consists of a sealed stainless steel box containing TMP and three electrode planes, where the middle plane is used for energy measurement, and the other two are highly segmented to enable a precise measurement of the position of electromagnetic showers. The position detector has been operated in electron and muon test beams at CERN. The detector performs well, both as an element of the calorimeter and as a device for measuring shower positions, and yields a spatial resolution of about 1 mm for high energy electron showers.

Performance of a prototype drift Chamber with 100 MHz FADC readout

Rectangular drift chamber cells have been constructed and tested using an electron test beam facility at DESY. A systematic study of the time, spatial, energy and double track resolutions with a 100 MHz FADC readout is presented. The spatial resolution is 100 to 120 μm and the double track resolution is 2.5 mm with an Ar:C 2H 6 (50:50) gas mixture at atmospheric pressure. The dE dx resolution obtained corresponds to 6% resolution for a 72-layer chamber.

Development of a prototype tapered cell drift chamber

Drift chamber cells have been constructed and tested using an electron test beam facility at DESY. The cells were operated under different voltage conditions and with different gas mixtures at 1 bar. Aspects of the construction and operation are discussed. Resolutions were typically less than 100 μm. The dependence of the drift cell resolution on distance from the sense wire and operating conditions are presented.

The Liquid-Argon-Endcap-Shower-Detector for TASSO

Forward going electrons and photons can be detected with the segmented liquid-argon-shower-detector built for the TASSO e+e--annihilation-detector at PETRA. In this communication a short description of the endcap-shower-detector will be given. Results obtained with an electron testbeam will be presented.

The Cleo Photon Shower Detector

We describe an electromagnetic shower detector which measures photon energies and positions, and provides charged particle tracking over a solid angle of 50% of 47? in the CLEO magnetic detector at the Cornell Electron Storage Ring. The detector is segmented into octants, each made of interleaved layers of proportional tubes and lead. The performance of the detector in an electron test beam and in initial e+e- annihilation experiments is discussed.