122599029
High energy proton damage effects in thin high resistivity FZ silicon detectors
Abstract The proposed luminosity upgrade of the Large Hadron Collider (S-LHC) will demand the inner most layers of the vertex detector to sustain fluences of about 10 16 charged hadrons/cm 2 . Due to the high multiplicity of tracks, the required spatial resolution and the extremely harsh radiation field thin silicon detector assemblies are proposed as a possible solution for this challenge. The radiation tolerance of 50 μm thin high resistivity float zone (FZ) devices has been studied for 24 GeV/ c protons in the fluence range between 4×10 13  cm −2 and 8.6×10 15  cm −2 . For the manufacturing of such thin devices, a technology based on direct wafer bonding and deep anisotropic etching was used. Annealing measurements at 80 °C have shown that the introduction rate g C in the stable damage component is about the same as observed for oxygen enriched FZ detectors and that the fluence dependence of the reverse annealing amplitude N Y exhibits a saturating function. It is also demonstrated that the annealing behavior of the reverse current related damage parameter α is independent on the fluence and the silicon material parameters. Charge collection efficiency (CCE) measurements were performed using 5.8 MeV α-particles. After fully annealing for about 31 days at 80 °C CCE was determined by extrapolation to be 66% at 10 16  p/cm 2 .
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.
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.
195868697
Irradiation tests of double-sided silicon strip detectors with a special guard ring structure
The results of the first irradiation tests of newly designed silicon microstrip detectors performed with 21 MeV protons at the Max-Planck-Institut in Heidelberg are presented. The detectors were developed and produced by the semiconductor laboratory of the Max-Planck-Institut in Munich. Novel guard ring structures allow operation of the detectors at voltages exceeding 300 V.
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.
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.
120394706
Construction and test of a full prototype drift-tube chamber for the upgrade of the ATLAS muon spectrometer at high LHC luminosities
Abstract For the planned high-luminosity upgrades of the Large Hadron Collider (LHC) background rates of neutrons and gamma rays of up to 14 kHz / cm 2 are expected which exceed the rate capability of the current ATLAS precision muon tracking detectors, the Monitored Drift Tube (MDT) chambers, with a drift tube diameter of 30 mm. Smaller diameter drift tube (sMDT) chambers with 15 mm tube diameter have been developed for upgrades of the ATLAS muon spectrometer. A full sMDT prototype chamber has been constructed and tested in a muon beam at CERN and with cosmic muons at high background irradiation rates of up to 95 kHz / cm 2 and 1400 kHz/tube. The test results demonstrate the required track reconstruction efficiency and spatial resolution of the sMDT chambers at background rates well beyond the maximum expected values at high-luminosity LHC. The sense wire locations in the prototype chamber have been measured with few microns precision with cosmic rays using precise reference chambers confirming the required wire positioning accuracy of better than the 20 μ m .
118584194
Construction and Test of MDT Chambers for the ATLAS Muon Spectrometer
Abstract The Monitored Drift Tube (MDT) chambers for the muon spectrometer of the ATLAS detector at the Large Hadron Collider (LHC) consist of 3–4 layers of pressurized drift tubes on either side of a space frame carrying an optical monitoring system to correct deformations. The full-scale prototype of a large MDT chamber has been constructed with methods suitable for large-scale production. X-ray measurements at CERN showed a positioning accuracy of the sense wires in the chamber of better than the required 20 μm (rms). The performance of the chamber was studied in a muon beam at CERN. Chamber production for ATLAS now has started.
122359864
Large-scale production of Monitored Drift Tube chambers for the ATLAS muon spectrometer
Abstract Precision drift tube chambers with a sense wire positioning accuracy of better than 20 μm are under construction for the ATLAS muon spectrometer. 70% of the 88 large chambers for the outermost layer of the central part of the spectrometer have been assembled. Measurements during chamber construction of the positions of the sense wires and of the sensors for the optical alignment monitoring system demonstrate that the requirements for the mechanical precision of the chambers are fulfilled.
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.
119295158
Performance of Drift-Tube Detectors at High Counting Rates for High-Luminosity LHC Upgrades
Abstract The performance of pressurized drift-tube detectors at very high background rates has been studied at the Gamma Irradiation Facility (GIF) at CERN and in an intense 20 MeV proton beam at the Munich Van-der-Graaf tandem accelerator for applications in large-area precision muon tracking at high-luminosity upgrades of the Large Hadron Collider (LHC). The ATLAS muon drift-tube (MDT) chambers with 30 mm tube diameter have been designed to cope with γ and neutron background hit rates of up to 500 Hz/cm 2 . Background rates of up to 14 kHz/cm 2 are expected at LHC upgrades. The test results with standard MDT readout electronics show that the reduction of the drift-tube diameter to 15 mm, while leaving the operating parameters unchanged, vastly increases the rate capability well beyond the requirements. The development of new small-diameter muon drift-tube (sMDT) chambers for LHC upgrades is completed. Further improvements of tracking efficiency and spatial resolution at high counting rates will be achieved with upgraded readout electronics employing improved signal shaping for high counting rates.