19455268
CDF run IIb silicon vertex detector DAQ upgrade
The Collider Detector at Fermilab (CDF) operates in the beamline of the Tevatron proton-antiproton collider at Batavia, IL. The Tevatron is expected to undergo luminosity upgrades (Run IIb) in the future, resulting in a higher number of interactions per beam crossing. To operate in this dense radiation environment, an upgrade of the CDF's silicon vertex detector subsystem and a corresponding upgrade of its VME-based DAQ system has been explored. Prototypes of all the Run IIb SVX DAQ components have been constructed, assembled into a test stand, and operated successfully using an adapted version of the CDF's network-capable DAQ software. In addition, a PCI-based DAQ system has been developed as a fast and inexpensive tool for silicon detector and DAQ component testing in the production phase. We present an overview of the Run IIb silicon DAQ upgrade, emphasizing the new features and improvements incorporated into the constituent VME boards and discuss a PCI-based DAQ system developed to facilitate production tests.
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.
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.
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.
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.
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.
119214048
Net-charge fluctuations and balance functions at the LHC
Abstract The measurement of event–by–event fluctuations and charge–dependent particle correlations are used to study properties of nuclear matter at high temperatures as produced in ultrarelativistic heavy–ion collisions. We present results for event–by–event net–charge fluctuations and charge balance functions in Δη and Δφ in Pb–Pb collisions at s NN = 2.76 TeV .
53579185
Higgs production and decay with a fourth Standard-Model-like fermion generation
State-of-the-art predictions for the Higgs-boson production cross section via gluon fusion and for all relevant Higgs-boson decay channels are presented in the presence of a fourth Standard-Model-like fermion generation. The qualitative features of the most important differences to the genuine Standard Model are pointed out, and the use of the available tools for the predictions is described. For a generic mass scale of 400−600 GeV in the fourth generation explicit numerical results for the cross section and decay widths are presented, revealing extremely large electroweak radiative corrections, e.g., to the cross section and the Higgs decay into WW or ZZ pairs, where they amount to about −50 % or more. This signals the onset of a non-perturbative regime due to the large Yukawa couplings in the fourth generation. An estimate of the respective large theoretical uncertainties is presented as well.
122289502
Development of SiTCP based DAQ system of double-sided silicon strip super-module
Abstract The super-module integration concept based on double-sided silicon strip modules has been developed for the future upgrade of the ATLAS detector. A super-module consists of 12 double-sided modules with 122 880 readout strips in total. Since the number of readout strips becomes very large to keep the hit occupancy at an acceptable level, the data readout is one of the key issues. A SiTCP based DAQ system has been developed by using the Soi EvAluation BoArd with Sitcp (SEABAS). The SEABAS processes the data by means of an FPGA (User-FPGA) and transfers data to a computer via Ether-net with the SiTCP protocol, which is a hardware implementation of TCP/IP on a FPGA device, enabling it to achieve high speed data transfers. The firmware and software have been developed for the SEABAS together with the readout hardware chain, and the basic functionality for reading out the super-module has been established.
123939194
Antinuclei production in heavy ion collisions at CERN SPS
Abstract Besides the dedicated search for strangelets NA52 measures light (anti)particle and (anti)nuclei production over a wide range of rapidity. Compared to previous runs the statistics has been increased in the 1998 run by more than one order of magnitude for negatively charged objects at different spectrometer rigidities. At a rigidity of −20 GeV/ c we measured 10 6 p , 10 3 d and one 3 He without any centrality requirements. These preliminary results together with previous measurements near central rapidity are discussed in the framework of a thermodynamical and a coalescence model.
109654831
Electrical performance of a silicon micro-strip super-module prototype for the High-Luminosity LHC collider
A major luminosity upgrade for the Large Hadron Collider (LHC) proton–proton collider at CERN is planned for ∼2022 to allow for peak luminosities of ∼5×1034cm−2s−1. The current inner tracker of the ATLAS experiment will be completely replaced to guarantee excellent tracking capabilities in an environment characterized by much higher detector occupancies and harsher radiation backgrounds as compared with the current LHC. The new tracker will be an all-silicon based system, with pixel detectors in the innermost layers and silicon micro-strip layers at outer radii. The so-called super-module concept is an integration solution proposed for the strip barrel region of the future ATLAS internal tracker. It consists of several double-sided silicon micro-strip modules assembled into a common light-weight support structure. A first electrical prototype of a super-module has been produced, aimed to exercise the readout chain and to investigate the noise performance of such a complex system. In this paper the super-module prototype is described and first electrical results are presented.