120324718
Integration, commissioning and installation of monitored drift tube chambers for the ATLAS barrel muon spectrometer
The ATLAS experiment at the Large Hadron Collider (LHC) at CERN is currently being assembled to be ready to take data in 2007. Its muon spectrometer is designed to achieve a momentum resolution better than 10% at 1 TeV. In the barrel part, a toroidal air-core magnet is instrumented with three layers of Monitored Drift Tube (MDT) chambers for precision tracking. The Max-Planck-Institut fur Physik and the Ludwig-Maximilians-University in Munich have built 88 MDT chambers for the outermost barrel layer. We report on our experience with the tests of the MDT chambers, their integration with the Resistive Plate trigger chambers and the installation of the muon stations in the experiment. First results of their commissioning in the ATLAS detector will be presented.
126243744
Measurement of the reaction π−p→π+π−n on a transversely polarized target at 17.2 GeV
Preliminary results from a high statistics measurement (1 M events) of the reaction π−p→π+π−n on strong polarization effects which must be attributed to amplitudes corresponding to ’’A1’’ exchange.
118899725
Test, Integration and Commissioning of Monitored Drift Tube Chambers for the ATLAS Barrel Muon Spectrometer
c Copyright owned by the author(s) under the terms of the Creative Commons Attribution-NonCommercial-ShareAlike Licence. The ATLAS experiment at the Large Hadron Collider (LHC) at CERN is currently being assembled and to be ready for data taking in 2007. In the barrel region of its muon spectrometer, a toroidal air-core magnet is instrumented with three layers of Monitored Drift Tube (MDT) chambers as precision tracking detectors; the middle and outer layers of drift chambers also carry Resistive Plate chambers (RPCs) of the trigger system. The barrel part of the spectrometer consists of a total of 682 muon stations, with sizes ranging from 1 m 2 to 11 m 2. The installation of the muon detectors has started in January 2005. At the of the second largest chamber type—each covering an area of up to 8 m 2 —are being built for the outermost barrel region. The MDT chambers have to pass a series of stringent tests before installation to ensure their proper operation in the experiment. At the production site in Munich, these tests include gas tightness, high voltage stability and measurements of the noise rate, and the response to cosmic muons. In addition, the individual wire positions and electronic time offsets of the drift tubes are determined from the cosmic ray data. After shipment to CERN, a subset of the tests is repeated and the MDT chambers are integrated on a common support frame with the trigger chambers. The completed muon station is is further checked with cosmic rays. All results are stored in the ATLAS commissioning database and constitute an important basis for LHC data taking. We present the test methods and results, an overview on the integration work of the muon detectors and report on the experience with the installation of the first stations in the ATLAS experiment.
108271361
Concepts for the readout of time projection chambers
While the use of CCD’s for the readout of TPC’s offers a reliable and ever more of the digitization concept. The problem of precision of currently available FADC’s is discussed together with two proposals for a solution.
120421514
GAS SYSTEM FOR ALEPH TPC
Abstract Operation of the time projection chamber of the ALEPH experiment at LEP requires a high-purity argon/methane gas mixture supplied to the detector under stable conditions to ensure minimum signal attenuation throughout the 43 m 3 detector volume (max. 2.2 m drift length) and maintain near-constant electron drift velocity in the gas over extended periods of time. Design considerations for a gas system to fulfil these conditions are presented and details given of the construction, operational aspects and of the achieved performance.
15415835
A Low Noise Pwc Cathode Readout System
A system has been developed, primarily to detect the induced charge deposited on PWC cathodes, which is versatile, fast and has a good signal to noise ratio for signals of ¿ 10-14 Coulomb input. The amplifier system, which is completely separated from the detector by 95¿ coaxial cables, is followed by a new charge integrating, version of the SHAM/BADC system developed at SLAC. This SHAM IV system is CAMAC based, allowing for computer calibration of the entire system from amplifier through ADC.
118063728
Mass Hierarchies versus proton Decay in MSSM Orientifold Compactifications
We review two systematic bottom-up analyses of MSSM quivers recently performed by the authors. We extend the analysis of arXiv:0905.3379 by including constraints arising from proton decay via dimension 5 operators and present all four-stack quivers in the Madrid embedding which satisfy this additional constraint. Furthermore, we investigate and make precise the interplay between mass hierarchies obtained via factorizable Yukawa textures and the presence of dimension 5 proton decay operators in MSSM orientifold compactifications. We discuss this issue in a five-stack quiver, first presented in arXiv:0909.4292, which exhibits proper mass hierarchies and no rapid proton decay.
59503820
Design and technology of DEPFET pixel sensors for linear collider applications
The performance requirements of vertex detectors for future linear collider experiments is very challenging especially for the detector's innermost sensor layers. The DEPleted Field Effect Transistor (DEPFET) combining detector and amplifier operation is capable to meet these requirements. A silicon technology is presented which allows production of large sensor arrays consisting of linear DEPFET detector structures. The envisaged pixel array offers a low noise and low power operation. To ensure a high radiation length a thinning technology based on direct wafer bonding is proposed.
110917125
Radiation hard strip detectors for large-scale silicon trackers
Abstract Major challenges in building silicon strip detectors for future high luminosity experiments are the high radiation level and the huge number of sensors required for the construction of the precision layers of the complete tracking system. Single-sided p + n strip detectors for ATLAS SCT designed and fabricated at the MPI Semiconductor Laboratory have been exposed to 3×10 14 /cm 2 24 GeV protons. The major features of the design, including the biasing technique using implanted resistors, are discussed and results are presented. The technology was transferred to CiS, Germany, a company capable of the desired large-scale production. Results of this industrially fabricated sensors look very promising and show the expected radiation hardness.
19809846
Development of Fast High-Resolution Muon Drift-Tube Detectors for High Counting Rates
Abstract Pressurized drift-tube chambers are efficient detectors for high-precision tracking over large areas. The Monitored Drift-Tube (MDT) chambers of the muon spectrometer of the ATLAS detector at the Large Hadron Collider (LHC) reach a spatial resolution of 35 μ m and almost 100% tracking efficiency with 6 layers of 30 mm diameter drift tubes operated with an Ar:CO 2 (93:7) gas mixture at 3 bar and a gas gain of 20 000. The ATLAS MDT chambers are designed to cope with background counting rates due to neutrons and γ rays of up to about 300 kHz per tube which will be exceeded for LHC luminosities larger than the design value of 10 34  cm −1  s −1 . Decreasing the drift-tube diameter to 15 mm while keeping the other parameters, including the gas gain, unchanged reduces the maximum drift time from about 700 to 200 ns and the drift-tube occupancy by a factor of 7. New drift-tube chambers for the endcap regions of the ATLAS muon spectrometer have been designed. A prototype chamber consisting of 12 times 8 layers of 15 mm diameter drift tubes of 1 m length has been constructed with a sense wire positioning accuracy of 20 μ m . The 15 mm diameter drift-tubes have been tested with cosmic rays in the Gamma Irradiation Facility at CERN at γ counting rates of up to 1.85 MHz.
118634238
Development of muon drift-tube detectors for high-luminosity upgrades of the Large Hadron Collider
Abstract The muon detectors of the experiments at the Large Hadron Collider (LHC) have to cope with unprecedentedly high neutron and gamma ray background rates. In the forward regions of the muon spectrometer of the ATLAS detector, for instance, counting rates of 1.7 kHz / cm 2 are reached at the LHC design luminosity. For high-luminosity upgrades of the LHC, up to 10 times higher background rates are expected which require replacement of the muon chambers in the critical detector regions. Tests at the CERN Gamma Irradiation Facility showed that drift-tube detectors with 15 mm diameter aluminum tubes operated with Ar : CO 2 ( 93 : 7 ) gas at 3 bar and a maximum drift time of about 200 ns provide efficient and high-resolution muon tracking up to the highest expected rates. For 15 mm tube diameter, space charge effects deteriorating the spatial resolution at high rates are strongly suppressed. The sense wires have to be positioned in the chamber with an accuracy of better than 50 μ m in order to achieve the desired spatial resolution of a chamber of 50 μ m up to the highest rates. We report about the design, construction and test of prototype detectors which fulfill these requirements.