63772749
Fault tolerant issues in the BTeV trigger
The BTeV trigger performs sophisticated computations using large ensembles of FPGAs, DSPs, and conventional microprocessors. This system will have between 5,000 and 10,000 computing elements and many networks and data switches. While much attention has been devoted to developing efficient algorithms, the need for fault-tolerant, fault-adaptive, and flexible techniques and software to manage this huge computing platform has been identified as one of the most challenging aspects of this project. They describe the problem and offer an approach to solving it based on a distributed, hierarchical fault management system.
108208419
Pixel Detector Test
117556562
Search for phi Mesons Produced at High Transverse Momenta in p - Be Collisions at 300-GeV
14474933
Charm results on CP violation and mixing
The most recent results on CP violation and mixing in the charm system are reviewed as a guide to the future. While no surprising results are reported so far, charm provides a unique window to physics beyond the Standard Model. The results reported here come from four sources, ALEPH at LEP, E791 and FOCUS/E831 at Fermilab, and CLEO II.V at CESR. Results beyond these sources may be expected as a byproduct of B-motivated experiments.
117907932
Observation of Structure in the $\Upsilon$ Region
The properties of the dimuon enhancement seen in 400-GeV proton-nucleus collisions have been clarified by a threefold increase in data. We find two peaks whose widths are consistent with our resolution: M/sub 1/ = 9.4 GeV with dsigma/dy vertical-bar /sub y/ = 1.8 x 10/sup -37/ cm/sup 2//nucleon and M/sub 2/ = 10.0 GeV with Bdsigma/dy vertical-bar /sub y/ = 0.7 x 10/sup -37/ cm/sup 2//nucleon. Evidence for the possible existence of a third peak near 10.4 GeV is discussed as are the comparison with the properties of a qq-bar system, where q is a new heavy quark.
370054
Development of a high density pixel multichip module at Fermilab
At Fermilab, both pixel detector multichip module and sensor hybridization are being developed for the BTeV experiment. The module is composed of three layers. The lowest layer is formed by the readout integrated circuits (ICs). The backs of the ICs are in thermal contact with the supporting structure, while the tops are flip-chip bump bonded to a pixel sensor. A low mass flex-circuit interconnect is glued on the top of this assembly, and the readout IC pads are wire-bonded to the circuit. The BTeV pixel detector is based on a design relying on this hybrid approach. This method offers maximum flexibility in the development process, choice of fabrication technologies, and the choice of sensor material. This paper presents strategies to handle the required data rate and performance characteristics of the pixel module prototypes.
53406377
Observation of very high energy gamma-rays from the AGN 1ES 2344+514 in a low emission state with the MAGIC telescope
The MAGIC collaboration has observed very high energy gamma-ray emission from the AGN 1ES 2344+514. A gamma-ray signal corresponding to an 11 excess and an integral flux of (2:38 0:30stat 0:70syst) ; 10 11 cm 2 s 1 above 200 GeV has been obtained from 23.1 hr of data taking between 2005 August 3 and 2006 January 1. The data confirm the previously detected gamma-ray emission from this object during a flare seen by the Whipple collaboration in 1995 and the evidence (below 5 significance level) from long-term observations conducted by the Whipple and HEGRA groups. The MAGIC observations show a relatively steep differential photon spectrum that can be described by a power law with a photon index of 1⁄4 2:95 0:12stat 0:2syst between 140 GeV and 5.4 TeV. The observations reveal a low-flux state, about 6 times below the 1995 flare seen by Whipple and comparable with the previous Whipple and HEGRA long-term measurements. During the MAGIC observations no significant time variability was observed. Subject headinggs: BL Lacertae objects: individual (1ES 2344+514) — gamma rays: observations Online material: color figures
118954339
Variable VHE gamma-ray emission from Markarian 501
The blazar Markarian 501 (Mrk 501) was observed at energies above 0.10 TeV with the MAGIC telescope from May through July 2005. The high sensitivity of the instrument enabled the determination of the flux and spectrum of the source on a night-by-night basis. Throughout our observational campaign, the flux from Mrk 501 was found to vary by an order of magnitude. Intra-night flux variability with flux-doubling times down to 2 minutes was observed during the two most active nights, namely June 30 and July 9. These are the fastest flux variations ever observed in Mrk 501. The ~20-minute long flare of July 9 showed an indication of a 4 +/- 1 min time delay between the peaks of F(<0.25 TeV) and F(>1.2 TeV), which may indicate a progressive acceleration of electrons in the emitting plasma blob. The flux variability was quantified for several energy ranges, and found to increase with the energy of the gamma-ray photons. The spectra hardened significantly with increasing flux, and during the two most active nights, a spectral peak was clearly detected at 0.43 +/- 0.06 TeV and 0.25 +/- 0.07 TeV, respectively for June 30 and July 9. There is no evidence of such spectral feature for the other nights at energies down to 0.10 TeV, thus suggesting that the spectral peak is correlated with the source luminosity. These observed characteristics could be accommodated in a Synchrotron-Self-Compton (SSC) framework in which the increase in gamma-ray flux is produced by a freshly injected (high energy) electron population.
16174766
Detection of VHE radiation from the BL Lac PG 1553+113 with the MAGIC telescope
In 2005 and 2006, the MAGIC telescope has observed very high energy gamma-ray emission from the distant BL Lac object PG 1553+113. The overall significance of the signal is 8.8 σ for 18.8 h observation time. The light curve shows no significant flux variations on a daily time-scale, the flux level during 2005 was, however, significantly higher compared to 2006. The differential energy spectrum between ∼ 90 GeV and 500 GeV is well described by a power law with photon index Γ = 4.2 ± 0.3. The combined 2005 and 2006 energy spectrum provides an upper limit of z = 0.74 on the redshift of the object. Subject headings: PG 1553+113, BL Lac, AGN, VHE gamma-ray, imaging air Cherenkov telescope
17364076
Observation of VHE gamma-ray emission from the Active Galactic Nucleus 1ES1959+650 using the MAGIC telecope
The MAGIC Cherenkov telescope has observed very high energy (VHE) gamma-ray emission from the Active Galactic Nucleus 1ES1959+650 during six hours in September and October 2004. The observations were carried out alternated with the Crab Nebula, whose data were used as reference source for optimizing gamma/hadron separation and for flux comparison. The data analysis shows VHE gamma-ray emission of 1ES1959+650 with ∼8σ significance, at a time of low activity in both optical and X-ray wavelengths. An integral flux above ∼ 180 GeV of about 20% of the Crab was obtained. The light curve, sampled over 7 days, shows no significant variations. The differential energy spectrum between 180 GeV and 2 TeV can be fitted with a power law of index -2.72 ± 0.14. The spectrum is consistent with the slightly steeper spectrum seen by HEGRA at higher energies, also during periods of low X-ray activity. Subject headings: 1ES1959+650, AGN, HBL, VHE gamma-ray, Cherenkov telescope Universität Würzburg, Germany Institut de Fisica d’Altes Energies, Barcelona, Spain Institute for Particle Physics, ETH Zürich, Switzerland Universidad Complutense, Madrid, Spain Universitat Autonoma de Barcelona, Spain Max-Planck-Institut für Physik, München, Germany Dipartimento di Fisica, Università di Padova, and INFN Padova, Italy Division of Experimental Physics, University of Lodz, Poland Dipartimento di Fisica, Università di Udine, and INFN Trieste, Italy Yerevan Physics Institute, Cosmic Ray Division, Yerevan, Armenia Tuorla Observatory, Pikkiö, Finland Institut für Physik, Humboldt-Universität Berlin, Germany University of California, Davis, USA Dipartimento di Fisica, Università di Siena, and INFN Pisa, Italy Space Research Unit, Potchefstroom University, South Africa Fachbereich Physik, Universität Dortmund, Germany Institute for Nuclear Research and Nuclear Energy, Sofia, Bulgaria
108150478
Testing of the TriP Chip Running at 132 nsec Using a Modified AFE Board
In this note we describe the first set of tests done with a sample of TriP chips that were mounted on a modified AFE board. The modifications consisted of different firmware and the replacement of one power supply switch. The board used was a standard AFEIc board (red type) on which new MCMs (MCMIIs) were mounted. The new MCMs were designed to support the TriP and emulate the SVX for readout when mounted on an AFEIc board. The TriP and the MCMs are described in Ref. [1]. Two versions of the MCMII were designed and built: one (MCMIIb) supports two TriP chips wirebonded directly to the MCM substrate. The other, (MCMIIc) supports one TriP which can be either wirebonded directly or packaged into a standard TQFP surface mount package. Due to space constraints, this MCM can support only 1 TriP. We tested 6 TriP chips on 3 different MCMIIb (MCMIIb-1, MCMIIb-2 and MCMIIb-3) and 2 other TriPs were tested on MCMIIc, one of them with an unpackaged TriP (MCMIIc-1) and the other with a packaged TriP (MCMIIc-2). A set of 10 programable internal registers control the TriP operation, the description of these registers can be found in [1]. Table 1 shows the values used for the tests described in this note. In Ref. [1] there is a description of the signals that are needed to operate the TriP chip. We implemented in a Field Programable Gate Array (FPGA), also part of the MCM, a set of shift registers that allow us to download via the 1553 interface to the AFE board, any desired timing for the signals that the FPGA has to send to the TriP chip. These registers are run with a 121.21 MHz clock (which is 16x the crossing clock and phase locked to it), which means that each bit corresponds to a time interval of 8.25 nsec. Finer control of timing is possible, but this changing the programing of the FPGA and recompiling. The bits downloaded to these shift registers inside the TriP are listed in Table 2.