13 research outputs found
Rare decays of the Z at LEP
No full textI discuss the preliminary results of the LEP experiments ALEPH, DELPHI, L3, and OPAL on the rare Z decays. Limits of about 105I−5 on the branching ratios are reported by most experiments. The question of excess in the ττV final state remains unsettled. From the analysis of the L3 data the ZZ′ mixing angle is confined to ±1.5° for most extensions of the Standard Model of electroweak interactions.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87709/2/1315_1.pd
Uncertain Hermite-Hadamard inequality for functions with (s,m)-Godunova-Levin derivatives via fractional integral
No full textSymposium in honor of Lawrence W. Jones : Tofigh Azemoon "Fifteen Years of the L3 Hadron Calorimeter"
No full textEnhanced mass transfer and water discharge in a proton exchange membrane fuel cell with a raccoon channel flow field
No full textThe cathode flow channel plays an important role in the water management of proton exchange membrane (PEM) fuel cells. In order to improve mass transfer and water management in traditional channels, this paper presents a new wavy flow field to increase the fuel cell performance and overall efficiency. A raccoon channel with various waviness parameters is numerically studied by a three-dimensional two-phase PEM fuel cell model. The electrochemical current-voltage performance results confirm that the PEM fuel cell's performance with the raccoon design is higher than a conventional straight channel at high current densities. The effects of uniform gas distribution, removal of the accumulated water, and sufficient water content in the membrane are crucial factors for improving cell performance. A parametric analysis is also performed by considering the amplitude and wavelength of the raccoon pattern on the fuel cell performance. The results show that the output power improves in the raccoon channel by increasing the amplitude or increasing the wavelength. The raccoon channel's output power with amplitude of 0.5 mm and a wavelength of 2 mm is enhanced by about 20%. The increase of performance in the raccoon channel is significantly higher than in the past reported studies
Design and Implementation of High Performance BPSK Demodulator for Satellite Communications
No full textThe Delfi program is a development line of small satellites comprising the successful Delfi-C3 and Delfi-n3Xt CubeSat missions. As part of an effort to involve radio amateurs from all over the world, a telemetry client is designed which allows radio amateurs to demodulate, decode and display telemetry data. This software was designed for an RF front-end connected to a sound card acting as low-end baseband sampling device. It has been discovered that there was a significant gap of 5 dB between the required Signal-to-Noise Ratio (SNR) for the software demodulator and the theoretical required link margin. This thesis presents an approach which decreases this gap while upgrading the demodulator for future use, taking advantage of emerging capabilities of Software Defined Radio (SDR) technology.Space Systems EngineeringAerospace Engineerin
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Real-time Data Access Monitoring in Distributed, Multi-petabyte Systems
No full textPetascale systems are in existence today and will become common in the next few years. Such systems are inevitably very complex, highly distributed and heterogeneous. Monitoring a petascale system in real-time and understanding its status at any given moment without impacting its performance is a highly intricate task. Common approaches and off-the-shelf tools are either unusable, do not scale, or severely impact the performance of the monitored servers. This paper describes unobtrusive monitoring software developed at Stanford Linear Accelerator Center (SLAC) for a highly distributed petascale production data set. The paper describes the employed solutions, the lessons learned, the problems still to be addressed, and explains how the system can be reused elsewhere
Operational Aspects of Dealing . . .
No full textTo date, the BaBar experiment has stored over 0.7PB of data in an Objectivity/DB database. Approximately half this data-set comprises simulated data of which more than 70 % has been produced at more than 20 collaborating institutes outside of SLAC. The operational aspects of managing such a large data set and providing access to the physicists in a timely manner is a challenging and complex problem. We describe the operational aspects of managing such a large distributed data-set as well as importing and exporting data from geographically spread BaBar collaborators. We also describe problems common to dealing with such large datasets
Test results from a uranium hadron calorimeter using wire chamber readout
No full textA uranium gas sampling calorimeter has been tested with electrons and pions between 1 and 50 GeV. A comparative evaluation of the response and the resolution for proportional and streamer mode operation of the gas wire chamber detectors is given for two different gas mixtures.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/26795/1/0000351.pd
On the Verge of One Petabyte - the Story Behind the BaBar Database System
No full textOn the behalf of BaBar Computing Group The BaBar database has pioneered the use of a commercial ODBMS within the HEP community. The unique object-oriented architecture of Objectivity/DB has made it possible to manage over 700 terabytes of production data generated since May'99, making the BaBar database the world's largest known database. The ongoing development includes new features, addressing the ever-increasing luminosity of the detector as well as other changin g physics requirements. Significant efforts are focused on reducing space requirements and operational costs. The paper discusses our experience with developing a large scale database system, emphasizing universal aspects which may be applied to any large scale system, independently of underlying technology used. 1
An enhancement in the ΛΛ invariant mass spectrum
No full textA 2.1 GeV/c K- exposure in a heavy liquid bubble chamber has been used to search for the final states KΛΛ. An enhancement in the ΛΛ invariant mass spectrum at 2370 MeV/c2 is interpreted as a possible resonance produced in Ξ-nucleon interactions. An estimate of the cross-section for ΛΛ production in Ξ-nucleus reations is given. © 1972.SCOPUS: ar.jinfo:eu-repo/semantics/publishe
