The Outer Tracker Detector of the HERA-B Experiment Part I: Detector

The HERA-B Outer Tracker is a large system of planar drift chambers with about 113000 read-out channels. Its inner part has been designed to be exposed to a particle flux of up to 2.10^5 cm^-2 s^-1, thus coping with conditions similar to those expected for future hadron collider experiments. 13 superlayers, each consisting of two individual chambers, have been assembled and installed in the experiment. The stereo layers inside each chamber are composed of honeycomb drift tube modules with 5 and 10 mm diameter cells. Chamber aging is prevented by coating the cathode foils with thin layers of copper and gold, together with a proper drift gas choice. Longitudinal wire segmentation is used to limit the occupancy in the most irradiated detector regions to about 20 %. The production of 978 modules was distributed among six different laboratories and took 15 months. For all materials in the fiducial region of the detector good compromises of stability versus thickness were found. A closed-loop gas system supplies the Ar/CF4/CO2 gas mixture to all chambers. The successful operation of the HERA-B Outer Tracker shows that a large tracker can be efficiently built and safely operated under huge radiation load at a hadron collider.Comment: 28 pages, 14 figure

Prompt K_short production in pp collisions at sqrt(s)=0.9 TeV

The production of K_short mesons in pp collisions at a centre-of-mass energy of 0.9 TeV is studied with the LHCb detector at the Large Hadron Collider. The luminosity of the analysed sample is determined using a novel technique, involving measurements of the beam currents, sizes and positions, and is found to be 6.8 +/- 1.0 microbarn^-1. The differential prompt K_short production cross-section is measured as a function of the K_short transverse momentum and rapidity in the region 0 < pT < 1.6 GeV/c and 2.5 < y < 4.0. The data are found to be in reasonable agreement with previous measurements and generator expectations.Comment: 6+18 pages, 6 figures, updated author lis

LHCb Calorimeters High Voltage System

The calorimeter system in LHCb aims to identify electrons, photons and hadrons. All calorimeters are equipped with Hamamatsu photo tubes as devices for light to signal conversion. Eight thousand R7899-20 tubes are used for electromagnetic and hadronic calorimeters and two hundred 64 channels multi-anode R7600-00-M64 for Scintillator-Pad/Preshower detectors. The calorimeter high voltage (HV) system is based on a Cockroft Walton (CW) voltage converter and a control board connected to the Experiment Control System (ECS) by serial bus. The base of each photomultiplier tube (PMT) is built with a high voltage converter and constructed on an individual printed circuit board, using compact surface mount components. The base is attached directly to the PMT. There are no HV cables in the system. A Field Programmable Gate Array (FPGA) is used on the control board as an interface between the ECS and the 200 control channels. The FPGA includes also additional functionalities allowing automated monitoring and ramp up of the high voltage values. This paper describes the HV system architecture, some technical details of the electronics implementation and summarizes the system performance. This safe and low power consumption HV electronic system for the photomultiplier tubes can be used for various biomedical apparatus too