P. G. Estabrooks

Study of beam-induced particle backgrounds at the LEP detectors

Abstract Synchrotron radiation photons and off-energy electrons which contribute to backgrounds in the LEP experiments have been simulated. A multi-faceted background protection system has been designed and installed which permits the experiments to take data under very clean conditions. The backgrounds measured at LEP1 are in good agreement with calculations. Simulations and studies have led to a design of enhanced background protection for LEP2 where far more severe photon background is expected. Detector sensitivity to backgrounds and monitor systems are described.

Electron signals in the Forward Calorimeter prototype for ATLAS

A pre-production prototype of the Forward Calorimeter (FCal) for the ATLAS detector presently under construction at the Large Hadron Collider (LHC) at CERN, Geneva, Switzerland, was exposed to electrons in the momentum range from 20 to 200 GeV/c in a test beam experiment at CERN in 1998. The measured performance, including a signal linearity within about ±1% and a high energy limit in the relative energy resolution of about 4%, meets the expectations for this kind of calorimeter, and exceeds the physics requirements for successful application in ATLAS.

The OPAL vertex drift chamber

Abstract A high precision vertex drift chamber has been installed in the OPAL experiment at LEP. The design of the chamber and the associated readout electronics is described. The performance of the system has been studied using cosmic ray muons and the results of these studies are presented. A space resolution of 50 μm in the drift direction is obtained using the OPAL central detector gas mixture at 4 bar.

SIMULATION STUDIES OF TRACKING SYSTEMS AT VERY HIGH LUMINOSITY

Abstract Detailed computer simulation studies of a tracking detector originally designed for high luminosity operation at the Superconducting Super Collider have been carried out. Detector simulation and track reconstruction techniques appropriate to the extremely high charged particle rates corresponding to luminosities of up to 10 34 cm −2 s −1 are described. The detector performance is evaluated and compared to design requirements stemming from the physics goals of the SDC experiment. The results have implications for the design of tracking detectors at future high luminosity hadron colliders such as the Large Hadron Collider (LHC).

High rate and ageing properties of MSGCs on plastic substrates

Abstract We describe the high-rate performance of MSGCs fabricated on thin plastic (Upilex) sheets. The surface of each device is treated by one of three methods to bring the resistivity within the appropriate range: ion-implantation, nickel oxide coating and Inconel oxide coating. We also describe preliminary ageing results and their local effect on the MSGC.

Charm Photoproduction Results from E691

We present results on the photoproduction of 10000 charmed particles from the 108 recorded triggers of Fermilab experiment E691. The total cross-section for the photoproduction of D° and D+ particles (and antiparticles) for x F >0.2 is measured to be 3.88±0.06±0.40 µb/Be nucleus at =145 GeV. We have also measured the relative production of different charmed particles, their p T 2 and X F distributions and the energy dependence of the total charm cross-section. The mean p T 2 , is 1.16±0.04 GeV2/c2 and the ratio of charm cross-sections at 200 GeV and 100 GeV is 1.96±0.24. Results of fits to the XF distribution are also reported.

Fabrication and test beam operation of plastic MSGCs

MicroStrip Gas Counters (MSGCs) have been fabricated with gold electrodes on ion-implanted Upilex (polyimide) using both wet-etch and lift-off processes. The quality of lithography from the wet-etch process has now improved to the point where there is less than one defect per (5 cm × 2 cm) print. Recently, four of these detectors were operated as a beam telescope at TRIUMF. They were read out through fast low-noise amplifiers into 100 MHz flash-ADCs and data are presented here on their efficiency, timing, and spatial resolution.