55139157
SLHC tracker upgrade: challenges and strategies in ATLAS
The Large Hadron Collider (LHC) will be upgraded to the Super-LHC in ≈2016 to provide a ten-fold increased luminosity and data rate. The inner silicon tracking detectors of the ATLAS and CMS experiments will be replaced by even more powerful devices. The new detectors will face unprecedented particle densities and radiation levels. Limiting the power consumption of the front-end electronics, distributing power efficiently and minimizing detector mass, while keeping the costs of the detector affordable, are key challenges. Possible design solutions and the status of R&D for ATLAS are described.
54868784
Series tests of fine mesh photomultiplier tubes in magnetic fields of up to 1.2 Tesla
Abstract The new lead/scintillating-fibre calorimeter (“SpaCal”) for the backward region of the H1 experiment at HERA (DESY) is equipped with fine mesh phototubes which operate in a magnetic field close to 1 T. A large sample of these tubes of the types Hamamatsu R5505 and R5506, and Hamamatsu R2490-05, have been tested in fields of up to 1.2T. We have investigated the cathode homogeneity with and without magnetic field, the gain loss under the influence of the magnetic field, and stability with time. For a subsample of tubes, we have performed additional studies on stability with respect to temperature changes, variation of gain as a function of the magnetic field, high voltage discharges, single photo-electron response, and linearity. We finally summarize the experience with these tubes after one year of operation in the experiment.
73602518
Radiation Resistant DC- DC Power Conversion with Voltage Ratios > 10 Capable of Operating in High Magnetic Field for LHC Upgrade Detectors
Commercial power converters that have voltage ratios greater than ten and are capable of running near the LHC collision region would increase the efficiency of the power distribution system of the ATLAS Silicon Tracker high luminosity upgrade. The devices must operate in a high magnetic field (2 T) and be radiation hard to ~50-100 Mrad and ~10 15 Neq/cm 2 . These converters are to be mounted on the same multi-chip modules as the ASIC readout chips or in close vicinity without introducing any additional readout noise due to the high switching frequencies. Such devices will permit higher voltage power delivery to the tracker and thus increase overall power efficiency by limiting the ohmic losses in the stretch of cable (about 100 meters) between the tracker and the power sources.
110237207
Evaluation of MCM-D technology for silicon strip detectors
Abstract Multi-chip Modules-Deposited (MCM-D) is a technology that can be applied to silicon strip modules and promises advantages in terms of integration complexity and material budget. This technology permits to integrate the front-end hybrid, pitch adaptor and wire bonds on the silicon sensor. The principle is to deposit alternating dielectric and metal layers directly on the silicon, where traces and vias are etched with high resolution to produce a PCB like structure. This paper reports on a prototype MCM-D processing run of silicon strip wafers performed to evaluate suitability of the technology. This first run uses one dielectric layer, one metal layer, passivation and a final metallisation appropriate for wire-bonding. Connections are done through the first dielectric layer to the strips, the bias ring, bias resistors and guard rings. Hence the effects of the post-processing on the silicon sensor are evaluated measuring change in parameters such as I / V and C / V characteristics, inter-strip capacitance and resistance.
121603383
Performance of an electromagnetic lead/scintillating-fibre calorimeter for the H1 detector
Abstract The properties of final modules of a high resolution lead/scintillating-fibre calorimeter to upgrade the backward region of the H1 detector were studied with electrons in the energy range from 2–60 GeV. The electromagnetic calorimeter consists of scintillating fibres with a diameter of 0.5 mm embedded in a lead matrix. This small fibre radius, in combination with a lead-to-fibre ratio of 2.27:1, ensures excellent energy resolution which has been measured to be δ/E=7.1%/ E/GeV ⊕ 1.0% . The spatial resolution as a function of energy for impact points at the center of a cell is given by 4.4 mm/ E/GeV + 1.0 mm . The time resolution was found to be better than 0.4 ns.
119863129
Performance of the H1 lead/scintillating-fibre calorimeter
Abstract In the winter-shutdown 1994/95 the backward region of the H1 detector has been equipped with a new lead/scintillating-fibre calorimeter. The purpose of the calorimeter is to perform precise measurements of the energy and the position of scattered electrons in ep collisions at HERA. In addition, the calorimeter determines the hadronic energy flow in the backward region and provides detailed trigger information and efficient background rejection exploiting the difference of impact times for physics events and beam related background events. The first data-taking experience with the new device is described.
10525627
Electroweak radiative corrections to single Higgs-boson production in e+e− annihilation
Abstract We have calculated the complete electroweak O (α) radiative corrections to the single Higgs-boson production processes e + e − →ν l ν l H ( l =e, μ , τ ) in the electroweak Standard Model. Initial-state radiation beyond O (α) is included in the structure-function approach. The calculation of the corrections is briefly described, and numerical results are presented for the total cross-section. In the G μ scheme, the bulk of the corrections is due to initial-state radiation, which affects the cross-section at the level of −7% at high energies and even more in the ZH threshold region. The remaining bosonic and fermionic corrections are at the level of a few percent. The confusing situation in the literature regarding differing results for the fermionic corrections to this process is clarified.
109891378
The DØ silicon micro-strip tracker
The D0 silicon micro-strip tracker (SMT) is part of the D0 upgrade for the Tevatron RunII at Fermilab. The detector has been running successfully since the start of the RunII physics data taking. The tracking and vertexing performance match the expectation from Monte-Carlo studies. An additional inner layer (Layer0) of silicon sensors at R = 1.6cm will be installed in 2005.
107061988
Design and assembly of double-sided silicon strip module prototypes for the ATLAS upgrade strip tracker
The LHC foresees a peak luminosity increase of up to ∼5×1034cm−2s−1 from ∼2022 with an integrated luminosity of ∼3000fb−1 before 2030. The current ATLAS Inner Detector will not stand the predicted radiation levels nor the expected large increase in the hit occupancy rates. A new inner tracker must therefore be designed, built and installed in a relatively short time-scale. The current layout assumes an all-silicon tracker with pixel detectors for the innermost layers and strip modules at higher radii. Major constraints are the requirements of radiation-hard sensors, efficient power distribution, minimum material budget, affordable cost, and fast and reliable production. This note reports on the design of double-sided silicon strip modules for the short-strip region of the upgraded ATLAS inner tracker. The different components of the module are described. The thermal performance is discussed. The assembly sequence of first module prototypes is explained in detail.
119401854
Charge transfer and charge broadening of GEM structures in high magnetic fields
Abstract We report on the measurements of charge transfer in Gas Electron Multipliers (GEM) structures in high magnetic fields. These were performed in the framework of the R&D work for a Time Projection Chamber at a future Linear Collider. A small test chamber has been installed in the aperture of a superconducting magnet with the GEM structures mounted perpendicular to the B -field direction. The charge transfer is derived from the electrical currents monitored during irradiation with an 55 Fe source. No significant loss of primary ionisation charge is observed, and an improved ion feedback suppression is achieved for high magnetic fields. Additionally, the width of the charge cloud released by individual 55 Fe photons is measured using a finely segmented strip readout after the triple GEM structure. Charge widths between 0.3 and 0.5 mm RMS are observed, which originate from the charge broadening inside the GEM amplification. This charge broadening is only partly suppressed at high magnetic fields.
109729787
Development of a silicon-microstrip super module prototype for the high luminosity LHC
Following the Phase II upgrade of the CERN Large Hadron Collider (LHC) currently foreseen in 2022–2023, the High Luminosity LHC (HL-LHC) is expected to deliver a peak luminosity in excess of 5×1034cm−2s−1 and an integrated luminosity of order 3000fb−1 until 2033. The ATLAS Collaboration plans to replace the existing Inner Tracking Detector by a new tracker, with readout electronics as well as silicon pixel and strip sensor technology capable of maintaining the excellent tracking performance of the existing tracker in the severe radiation and high collision rate environment of the HL-LHC. The promising super-module integration concept extends the proven design of the existing barrel silicon strip tracker to the HL-LHC, with double-sided stereo silicon micro-strip modules assembled into a low mass local support structure. The Super-Module R&D program is described, with reference to HL-LHC requirements, and key prototype results are summarized.