Paul Mockett

Measurement of the inclusive decay properties of charmed mesons

Abstract We report a high statistics study of the inclusive decay properties of the charmed D0 and D+ mesons, and the first inclusive study of the charmed Ds+. The data are collected at s =3.77 GeV and s =4.14 GeV with the Mark III detector at the e+e− storage ring SPEAR. For each charmed meson species, the charged-particle multiplicity, the strangeness content of the final state, and the average π0 multiplicity are determined.

SLD Liquid Argon Calorimeter Prototype Test Results

The results of the SLD test beam program for the selection of a calorimeter radiator composition within a liquid argon system are described, with emphasis on the study of the use of uranium to obtain equalization of pion and electron responses.

Neutron and gamma radiation tests of the analog devices TMP37 temperature sensors

The Analog Devices TMP37 temperature sensor is used to monitor the temperature gradients in the US Atlas End Cap Muon Chambers. It was chosen because of its stability, linearity, high output signal, and especially the low self-heating. We have irradiated samples of these sensors with neutrons and gamma rays. The results of these measurements are presented.

Study of ATLAS monitored drift tube flushing

The ATLAS monitored drift tube (MDT) muon tracking detector system consists of about 1,200 large-scale MDT chambers built from some 400,000 individual aluminum tubes of 3 cm diameter, and lengths ranging from approximately 1 to 6 meters. This MDT system has a total gas volume of 800 m/sup 3/. Both during the many years of chamber preparation, testing, commissioning and after their later installation in ATLAS, the chamber gas has to be refreshed or replaced periodically. In cases where the chamber gas shall be replaced, it would be of great advantage (cost, time) to know how to remove the old gas in the most efficient manner. Frequently chambers are pressurized and then depressurized three or more times. We have examined an alternate method of just flushing at atmospheric pressure and determined how many volume exchanges of gas are needed until the new gas will have replaced the old gas during the flushing process to a very high degree of purity. It is shown that after 1.8 volume exchanges (perhaps even less) at atmospheric pressure the gas is replaced at the 99.9%-level. Results of these studies and a method of visualization of the flushing process, shown in real-time, how the old gas is replaced by the new gas in an MDT-like setup, are presented.

Experience gained in the certification of Seattle MDT ATLAS end-cap chambers

ATLAS monitored drift tube (MDT) chambers are composed of precision muon drift tubes assembled into arrays to form base chambers. Each tube wire in a chamber is located to a precision of 25 microns to provide large area precision chambers for the measurement of muons produced in high-energy collisions at the LHC. Following the completion of 80 MDT base chambers we have been through a process at Seattle and CERN of certifying their operational readiness for ATLAS. The certification process involved a recheck of the gas tightness, the addition of the high voltage and signal electronics cards, the cabling, the testing and conditioning for dark current at high voltage and ultimately collecting millions of cosmic ray events for each MDT. This paper reviews the results, the problems and the repairs performed during the certification. Analysis of the cosmic ray events provides an insight into occasional anomalies in tube function.

A LOW COST CAN NODE FOR A/D MEASUREMENTS IN ATLAS

We have developed a CAN node suitable for A/D measurements and data I/O in the Muon Spectrometer for ATLAS. It is based on commercial hardware and software from Phytec Corporation [1] and programming software from Keil Software[2] and DAvE [3]. The advantages besides very low cost are commercial design and ease of programming and debugging. Phytec provides a CAN node based on the Siemens’ C515C 8 bit microprocessor [4] and provides tools for downloading programs. Keil Software supplies an integrated development environment for programming the C515CC. The CAN node along with 48 channels of TMP37 [5] temperature sensors has been radiation tested to 1 10 12

A novel segmentation for charge sampling calorimeters

Abstract A novel segmentation for charge sampling calorimeter towers is proposed which makes possible the precision measurement of shower position and width. It also allows the positions and energies of two showers within the same tower to be determined. With this segmentation a tower may lose a channel or the high voltage short to ground without degrading the hermeticity. In comparison with the indicated channel counts for the SSC calorimeters, this novel segmentation requires significantly fewer channels.

Measurement of the branching fractions for D0-e and D0K-ee and determination of Vcd/Vcs-2

Measurements of the exclusive branching fractions B(D^0→π^-e^+ν_e) and B(D^0→K^-e^+ν_e), using data collected at the ψ(3770) with the Mark III detector at the SLAC e^+e^- storage ring SPEAR, are used to determine the ratio of the Kobayashi-Maskawa matrix elements │V_(cd)/V_(cs)│^2 =0.057_(-0.015)^(+0.038)±0.005.

Search for the decay D0K0e+e-

A search for the decay of the charmed meson /ital D//sup 0//r arrow//bar K//sup 0/e/sup +/e/sup /minus// is presented, based on data collected at the /psi/(3770) resonance with the Mark III detector at the SLAC storage ring SPEAR. No evidence for this process is found, resulting in an upper limit on the decay branching ratio of 1.7/times/10/sup /minus/3/ at the 90% confidence level.