121506437
Gluing silicon with silicone
Abstract Problems and solutions concerning the gluing of silicon detectors are discussed. The R & D work for the HERA- B vertex detector system led to gluing studies with epoxy and silicone-based adhesives used on ceramics and carbon fibre. The HERA- B solution using a silicone glue is presented.
120274396
Timing properties of an avalanche diode for single photon counting
A new concept for a silicon single photon counter has been developed at the Semiconductor Laboratory of the Max-Planck-Institute for Physics. The concept combines the principles of a drift diode and an avalanche diode. The electron which is generated by an incoming photon has to drift to the small avalanche region and avalanche breakdown will take place. The detector is operated in Geiger mode. In order to provide high efficiency and good timing properties, the electrons have to be focussed properly with short time jitter. Therefore, drift and timing properties have been investigated using simulations.
73653251
Imaging performance of a DEPFET pixel Bioscope system in Tritium autoradiography
Abstract A Bioscope system based on a 64 × 64 -matrix of DEPFET pixels has been developed for real-time digital autoradiography in biomedical applications. It provides very good energy and spatial resolution at the same time. The DEPFET pixel cells consist of p -channel JFETs integrated into the high-ohmic n -silicon substrate. This leads to a very low noise performance at room temperature. Two dedicated ASIC chips have been developed for steering and readout of the pixel matrix. The measured system noise of ( 69 ± 4 ) e - at 35 ∘ C is mostly due to sensor leakage current and can be largely reduced by cooling or a faster readout. The spatial resolution is examined by measurements with a laser as well as with a dedicated test chart and is determined to be ( 6.7 ± 0.7 ) μ m for 6 keV-X-rays and 4.3 ± 0.8 μ m for 22 keV-X-rays. The measurements are compared to simulation results with different reconstruction algorithms. Due to the thin entrance window at the detector backside and the low noise performance, a detection of low-energy β -emitters such as 3H is possible. Measurements with 3H-labeled biological samples were taken. The ability of the DEPFET pixel Bioscope to separate different radiolabels in the same sample is demonstrated by a measurement with 3H and 14C.
108645383
The ATLAS Silicon Pixel Sensors
Abstract Prototype sensors for the ATLAS silicon pixel detector have been developed. The design of the sensors is guided by the need to operate them in the severe LHC radiation environment at up to several hundred volts while maintaining a good signal-to-noise ratio, small cell size, and minimal multiple scattering. The ability to be operated under full bias for electrical characterization prior to attachment of the readout integrated circuit electronics is also desired.
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.
34283775
Tracking and level-1 triggering in the forward region of the ATLAS muon spectrometer at sLHC
In the endcap region of the ATLAS Muon Spectrometer (η  >  1) precision tracking and Level-1 triggering are performed by different types of chambers. Monitored Drift Tube chambers (MDT) and Cathode Strip Chambers (CSC) are used for precision tracking, while Thin Gap Chambers (TGC) form the Level-1 muon trigger, selecting muons with high transverse momentum (pT). When by 2018 the LHC peak luminosity of 1034 cm−2s−1 will be increased by a factor of ~ 2 and by another factor of ~ 2–2.5 in about a decade from now (``SLHC''), an improvement of both systems, precision tracking and Level-1 triggering, will become mandatory in order to cope with the high rate of uncorrelated background hits (``cavern background'') and to stay below the maximum trigger rate for the muon system, which is in the range of 10–20 % of the 100 kHz rate, allowed for ATLAS. For the Level-1 trigger of the ATLAS Muon Spectrometer this means a stronger suppression of sub-threshold muons in the high-pT trigger as well as a better rejection of tracks not coming from the primary interaction point. Both requirements, however, can only be fulfilled if spatial resolution and angular pointing accuracy of the trigger chambers, in particular of those in the Inner Station of the endcap, are improved by a large factor. This calls for a complete replacement of the currrently used TGC chambers by a new type of trigger chambers with better performance. In parallel, the precision tracking chambers must be replaced by chambers with higher rate capability to be able to cope with the intense cavern background. In this article we present concepts to decisively improve the Level-1 trigger with newly developed trigger chambers, being characterized by excellent spatial resolution, good time resolution and sufficiently short latency. We also present new types of precision chambers, designed to maintain excellent tracking efficiency and spatial resolution in the presence of high levels of uncorrelated background hits, as generated by γ and neutron conversions.
23063408
Use of Triple Modular Redundancy (TMR) technology in FPGAs for the reduction of faults due to radiation in the readout of the ATLAS monitored drift tube (MDT) chambers
The Triple Modular Redundancy (TMR) technology allows protection of the functionality of FPGAs against single event upsets (SEUs). Each logic block is implemented three times with a 2-out-of-3 voter at the output. Thus, the correct logical value is available even if there is an upset bit in one location. We applied TMR to the configuration code of a Virtex-II-2000 FPGA, which serves as the on-chamber readout processor of the ATLAS monitored drift tubes (MDTs). We describe the code implementation, results of performance measurements and discuss several limitations of the method. Finally, we present a supplementary technology called “scrubbing”. It permanently checks the configuration memory while the FPGA is operating, and corrects upset configuration bits when necessary.
3135633
Operation of the ATLAS muon drift-tube chambers at high background rates and in magnetic fields
In the ATLAS muon spectrometer, large drift-tube chambers are used for precision tracking. The chambers will be operated at a high neutron and /spl gamma/ background resulting in count rates of up to 500 Hz cm/sup -2/ corresponding to 300 kHz per tube. The spatial resolution of the drift tubes is degraded from 82 /spl mu/m without background to 108 /spl mu/m at 500 Hz cm/sup -2/ background count rate. Due to afterpulsing in the Ar/CO/sub 2/ gas mixture used in the drift tubes, ionizing radiation causes more than one hit in a tube within the maximum drift time of about 800 ns which is expected for magnetic field strengths around 1.2 T. In order to limit the count rate, the drift tubes are read out with an artificial dead time of 790 ns which causes an efficiency loss of 23% at a rate of 300 kHz per tube. The space-to-drift-time relationship of the tubes varies with background rate, temperature, and magnetic field strength. The mean magnetic field strength in a muon chamber is 0.4 T on the average, but may vary by up to 0.4 T within a chamber. The space-to-drift-time relationship must therefore be determined in short time intervals with an accuracy better than 20 /spl mu/m using muon tracks and applying corrections for measured magnetic field variations.
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.
37514459
A Flash ADC System for TPC Readout
We present the outline of a data taking system that uses waveform recording for 50,000 electronic channels. This system will be used for the readout of a Time Projection Chamber which serves as the central detector of the ALEPH experiment at LIP. The requirements of the digitizing system are discussed, together with the problem of data reduction.
50340039
Observation of a Narrow Resonance at 10.02-GeV in e+ e- Annihilations
Abstract The ϒ′ state has been observed as a narrow resonance at M ( ϒ ′) = 10.02 ± 0.02 GeV in e + e − annihilations, using a NaI and lead-glass detector in the DORIS storage ring at DESY. The ratio Г ee Г had /Г tot of electronic, hadronic, and total widths has been measured to be 0.32 ± 0.13 keV. The parameters of the Г particle have also been determined to be/ M (Г)