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.
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.
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.
17193732
JET PRODUCTION AT HERA : PROGRESS AND PROBLEMS
This contribution reviews the measurements related to jet production at HERA which are available in`98. The reasons for the considerable progress achieved in the last years are summarized. The major diiculties and the limitations of these measurements as seen today are discussed. 1. What has been measured ? One of the many fascinating topics of research at the electron{proton collider HERA is the study of multi{jet events. The application of jet algorithms to characterize the properties of multi{particle hadronic nal states turned out to be a powerful and natural approach. Jet algorithms have been used intensively in the analysis of deeply inelastic scattering (DIS) and photoproduction processes. In leading{order QCD, the cross section of multi{jet events in DIS is proportional to the strong coupling constant s and the parton density functions of the proton. Several determinations of s based on jets have been performed at HERA 1, 2, 3, 4]. There are (preliminary) extractions of the proton's gluon content in NLO 5]. This approach is more direct than determinations of the gluon density from inclusive structure function measurements, and it probes the gluon density at larger momentum fractions. Events with a jet in the very forward (proton) direction of the detectors have been studied in attempts to search for signatures expected when the BFKL parton density evolution equations are valid at HERA 6]. In photoproduction, evidence for the partonic structure of the photon has been shown in studies of jet distributions 7]. In events with two reconstructed jets x , the share of the photon's momentum entering the hard scattering process, can be calculated. From the measurement of dijet cross sections diierential in x and transverse jet energy, photon parton densities could be constrained, and the p t dependence of the anomalous component of the real photon predicted by QCD could be connrmed 8]. Jet polar angle distributions for direct and resolved photons where measured to be sensitive to the spin of the corresponding gluon or quark propagators 9]. Also, LO eeective parton densities were extracted 8].
121921718
Hadronic response and e / pi separation with the H1 lead / fiber calorimeter
Hadronic response and electron identification performance of the new H1 lead-scintillating fibre calorimeter are investigated in the 1 to 7 GeV energy range using data taken at the CERN Proton Synchrotron. The energy response to minimum ionizing particles and interacting pions are studied and compared to Monte Carlo simulations. The measured energy of pions interacting either in the electromagnetic or in the hadronic section is found to scale linearly with the incident energy, providing an energy resolution σE ∼ 38% within a depth of one interaction length and σE ∼ 29% for a total depth of two interaction lengths. Several electron identification estimators are studied and combined as a function of energy and impact point. The probability for pions to be misidentified as electrons of any measured energy above 1 GeV ranges from 5% (for 2 GeV incident pions) to 0.4% (at 7 GeV) for an electron detection efficiency of 90%. The probability for pions of a given energy to be misidentified as electrons of the same energy falls to 0.25% at 7 GeV.
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.
14164208
A prototype liquid Argon Time Projection Chamber for the study of UV laser multi-photonic ionization
This paper describes the design, realization and operation of a prototype liquid Argon Time Projection Chamber (LAr TPC) detector dedicated to the development of a novel online monitoring and calibration system exploiting UV laser beams. In particular, the system is intended to measure the lifetime of the primary ionization in LAr, in turn related to the LAr purity level. This technique could be exploited by present and next generation large mass LAr TPCs for which monitoring of the performance and calibration play an important role. Results from the first measurements are presented together with some considerations and outlook.
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.
114185756
Operational experience with the D0 silicon tracker
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.
116623294
EndCap Module Production for the ATLAS Silicon Tracker (SCT) at CERN and the University of Geneva
This note describes the infrastructure, procedure and quality assurance for the construction of approximately one third of the endcap modules for the ATLAS Semiconductor Tracker (SCT) by groups from the University of Geneva and CERN.