108217011
Upgrade of the CMS Pixel Detector
109400943
Upgrade plans for the CMS pixel barrel detector
Abstract The pixel detector of the CMS experiment will need to be replaced after a couple of years of LHC running because of radiation damage. On the other hand, plans for a step wise luminosity upgrade of the accelerator beyond the present design value around 2014 are being prepared. While the replacement pixel detector must be designed to handle increased particle rates, it should maintain or improve the tracking performance of the present system and must be compatible with existing services.
119151118
Mechanical design and material budget of the CMS barrel pixel detector
The Compact Muon Solenoid experiment at the Large Hadron Collider at CERN includes a silicon pixel detector as its innermost component. Its main task is the precise reconstruction of charged particles close to the primary interaction vertex. This paper gives an overview of the mechanical requirements and design choices for the barrel pixel detector. The distribution of material in the detector as well as its description in the Monte Carlo simulation are discussed in detail.
109648920
Assembly of the CMS pixel barrel modules
For the barrel part of the CMS pixel tracker about 800 silicon pixel detector modules are required. The modules are bump bonded, assembled and tested at the Paul Scherrer Institute. This article describes the assembly procedure that will be used to build these modules.
121281729
Beam test measurements on GaAs pixel detectors at various angles of incidence
Abstract A GaAs pixel detector constructed in Aachen has been tested in a 4 GeV electron beam at DESY. The experimental setup allowed tilting the detector with respect to the beam line with angles of incidence from 0° to 45°. The sensor-array consisted of 8 × 16 pixels with a size of 125 × 125 μm 2 each. The detector was made of a 250μm thick Freiberger SI-GaAs wafer. An improved contact was formed on the backside, allowing safe operation of the detector in the soft breakdown regime. A double metal technique allowed bonding the single pixels linearly to the readout-chip. Using the the fast PreMux128 preamplifier multiplexer chip ( τ p = 40 ns ) a signal to noise ratio of 29 was obtained for a beam angle of incidence of 0° increasing up to 38 for 45°. The spatial resolution obtained with an angle of incidence of 45° was (9.0 ± 6.0) μm while the resolution of the untilted detector is equal to the digital one (36.1μm). For these testbeam-measurements the detector was connected to the electronics via wire-bonds. For future experiments bump-bonding connections are required. The results of a process for the formation of bump-bond connections on GaAs pixeldetectors are shown.
18347743
Building CMS pixel barrel detector modules
For the barrel part of the CMS pixel tracker about 800 silicon pixel detector modules are required. The modules are bump bonded, assembled and tested at the Paul Scherrer Institute. This article describes the experience acquired during the assembly of the first ∼200 modules.
120184923
Recent and ongoing ageing studies for the Atlas muon spectrometer drift tubes
Abstract The Atlas muon spectrometer relies on Monitored Drift Tubes (MDTs) for track reconstruction in most regions. Expected count rates due to photons reach up to 1500 Hz/cm for the innermost MDTs. For a gas gain of 2 × 10 4 , this corresponds to an overall accumulated charge of up to 0.6 C/cm, which the MDTs must be able to withstand in 10 years of LHC operation without a degradation in their performance. With the main MDT parameters and the design frozen and chamber production well under way, the focus of present ageing studies is on testing final Atlas chambers instead of using small, dedicated setups under very well-controlled conditions as in the past. This paper summarizes the results of such a study performed at the CERN Gamma Irradiation Facility GIF under realistic Atlas conditions. One of the main goals was to evaluate for the first time the principle of gas recirculation and a prototype of the Atlas circulation system. The paper also reviews ongoing measurements at CERN and in Freiburg.