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3D circuit integration for Vertex and other detectors (open access)

3D circuit integration for Vertex and other detectors

High Energy Physics continues to push the technical boundaries for electronics. There is no area where this is truer than for vertex detectors. Lower mass and power along with higher resolution and radiation tolerance are driving forces. New technologies such as SOI CMOS detectors and three dimensional (3D) integrated circuits offer new opportunities to meet these challenges. The fundamentals for SOI CMOS detectors and 3D integrated circuits are discussed. Examples of each approach for physics applications are presented. Cost issues and ways to reduce development costs are discussed.
Date: September 1, 2007
Creator: Yarema, Ray
System: The UNT Digital Library
Accuracy and Efficiency of a Coupled Neutronics and Thermal Hydraulics Model (open access)

Accuracy and Efficiency of a Coupled Neutronics and Thermal Hydraulics Model

The accuracy requirements for modern nuclear reactor simulation are steadily increasing due to the cost and regulation of relevant experimental facilities. Because of the increase in the cost of experiments and the decrease in the cost of simulation, simulation will play a much larger role in the design and licensing of new nuclear reactors. Fortunately as the work load of simulation increases, there are better physics models, new numerical techniques, and more powerful computer hardware that will enable modern simulation codes to handle the larger workload. This manuscript will discuss a numerical method where the six equations of two-phase flow, the solid conduction equations, and the two equations that describe neutron diffusion and precursor concentration are solved together in a tightly coupled, nonlinear fashion for a simplified model of a nuclear reactor core. This approach has two important advantages. The first advantage is a higher level of accuracy. Because the equations are solved together in a single nonlinear system, the solution is more accurate than the traditional “operator split” approach where the two-phase flow equations are solved first, the heat conduction is solved second and the neutron diffusion is solved third, limiting the temporal accuracy to 1st order because the …
Date: September 1, 2007
Creator: Mousseau, Vincent A. & Pope, Michael A.
System: The UNT Digital Library
Addressing the Pilot security problem with gLExec (open access)

Addressing the Pilot security problem with gLExec

The Grid security mechanisms were designed under the assumption that users would submit their jobs directly to the Grid gatekeepers. Many groups are however starting to use pilot-based infrastructures, where users submit jobs to a centralized queue and are successively transferred to the Grid resources by the pilot infrastructure. While this approach greatly improves the user experience, it does introduce several security and policy issues, the more serious being the lack of system level protection between the users and the inability for Grid sites to apply fine grained authorization policies. One possible solution to the problem is provided by gLExec, a X.509 aware suexec derivative. By using gLExec, the pilot workflow becomes as secure as any traditional one.
Date: September 1, 2007
Creator: Sfiligoi, I.; Koeroo, O.; Venekamp, G.; Yocum, D.; Groep, D. & Petravick, D.
System: The UNT Digital Library
Advances in Development of the Fission Product Extraction Process for the Separation of Cesium and Strontium from Spent Nuclear Fuel (open access)

Advances in Development of the Fission Product Extraction Process for the Separation of Cesium and Strontium from Spent Nuclear Fuel

The Fission Product Extraction (FPEX) Process is being developed as part of the United States Department of Energy Advanced Fuel Cycle Initiative for the simultaneous separation of cesium (Cs) and strontium (Sr) from spent light water reactor (LWR) fuel. Separation of the Cs and Sr will reduce the short-term heat load in a geological repository, and when combined with the separation of americium (Am) and curium (Cm), could increase the capacity of the geological repository by a factor of approximately 100. The FPEX process is based on two highly specific extractants: 4,4',(5')-Di-(t-butyldicyclo-hexano)-18-crown-6 (DtBuCH18C6) and Calix[4]arene-bis-(tert-octylbenzo-crown-6) (BOBCalixC6). The DtBuCH18C6 extractant is selective for strontium and the BOBCalixC6 extractant is selective for cesium. Results of flowsheet testing of the FPEX process with a simulated feed solution in 3.3-cm centrifugal contactors are detailed. Removal efficiencies, distribution coefficient data, coextraction of metals, and process hydrodynamic performance are discussed along with recommendations for future flowsheet testing with actual spent nuclear fuel.
Date: September 1, 2007
Creator: Law, JAck D.
System: The UNT Digital Library
Advances in U.S. Heavy Ion Fusion Science (open access)

Advances in U.S. Heavy Ion Fusion Science

During the past two years, the US heavy ion fusion science program has made significant experimental and theoretical progress in simultaneous transverse and longitudinal beam compression, ion-beam-driven warm dense matter targets, high-brightness beam transport, advanced theory and numerical simulations, and heavy ion target physics for fusion. First experiments combining radial and longitudinal compression {pi} of intense ion beams propagating through background plasma resulted in on-axis beam densities increased by 700X at the focal plane. With further improvements planned in 2008, these results enable initial ion beam target experiments in warm dense matter to begin next year. They are assessing how these new techniques apply to higher-gain direct-drive targets for inertial fusion energy.
Date: September 1, 2007
Creator: Logan, B. G.; Barnard, J. J.; Bieniosek, F. M.; Cohen, R. H.; Coleman, J. E.; Davidson, R. C. et al.
System: The UNT Digital Library
Astrophysics Motivation behind the Pierre Auger Southern Observatory Enhancements (open access)

Astrophysics Motivation behind the Pierre Auger Southern Observatory Enhancements

The Pierre Auger Collaboration intends to extend the energy range of its southern observatory in Argentina for high quality data from 0.1 to 3 EeV. The extensions, described in accompanying papers, include three additional fluorescence telescopes with a more elevated field of view (HEAT) and a nested surface array with 750 and 433 m spacing respectively and additional muon detection capabilities (AMIGA). The enhancement of the detector will allow measurement of cosmic rays, using the same techniques, from below the second knee up to the highest energies observed. The evolution of the spectrum through the second knee and ankle, and corresponding predicted changes in composition, are crucial to the understanding of the end of Galactic confinement and the effects of propagation on the lower energy portion of the extragalactic flux. The latter is strongly related to the cosmological distribution of sources and to the composition of the injected spectrum. We discuss the science motivation behind these enhancements as well as the impact of combined HEAT and AMIGA information on the assessment of shower simulations and reconstruction techniques.
Date: September 1, 2007
Creator: Medina-Tanco, Gustavo & Collaboration, for the Pierre Auger
System: The UNT Digital Library
ATR LEU Fuel and Burnable Absorber Neutronics Performance Optimization by Fuel Meat Thickness Variation (open access)

ATR LEU Fuel and Burnable Absorber Neutronics Performance Optimization by Fuel Meat Thickness Variation

The Advanced Test Reactor (ATR) is a high power density and high neutron flux research reactor operating in the United States. Powered with highly enriched uranium (HEU), the ATR has a maximum thermal power rating of 250 MWth. Because of the large test volumes located in high flux areas, the ATR is an ideal candidate for assessing the feasibility of converting an HEU driven reactor to a low-enriched core. The present work investigates the necessary modifications and evaluates the subsequent operating effects of this conversion. A detailed plate-by-plate MCNP ATR 1/8th core model was developed and validated for a fuel cycle burnup comparison analysis. Using the current HEU U 235 enrichment of 93.0 % as a baseline, an analysis can be performed to determine the low-enriched uranium (LEU) density and U-235 enrichment required in the fuel meat to yield an equivalent K-eff between the HEU core and the LEU core versus effective full power days (EFPD). The MCNP ATR 1/8th core model will be used to optimize the U-235 loading in the LEU core, such that the differences in K-eff and heat flux profile between the HEU and LEU core can be minimized. The depletion methodology MCWO was used to …
Date: September 1, 2007
Creator: Chang, G. S.
System: The UNT Digital Library
CFD Analysis of Turbulent Flow Phenomena in the Lower Plenum of a Prismatic Gas-Cooled Reactor (open access)

CFD Analysis of Turbulent Flow Phenomena in the Lower Plenum of a Prismatic Gas-Cooled Reactor

This paper is concerned with the implementation of a computational model of turbulent flow in a section of the lower plenum of Very High Temperature Reactor (VHTR). The proposed model has been encoded in a state-of-the-art CFD code, NPHASE. The results of NPHASE predictions have been compared against the experimental data collected using a scaled model of a sub-region in the lower plenum of a modular prismatic gas-cooled reactor. It has been shown that the NPHASE-based model is capable of predicting a three-dimensional velocity field in a complex geometrical configuration of VHTR lower plenum. The current and future validations of computational predictions are necessary for design and analysis of new reactor concepts, as well as for safety analysis and licensing calculations.
Date: September 1, 2007
Creator: Gallaway, T.; Antal, S.P.; Podowski, M.Z. & Guillen, D.P.
System: The UNT Digital Library
CHARACTERIZATION OF AN ADVANCED GADOLINIUM NEUTRON ABSORBER ALLOY BY MEANS OF NEUTRON TRANSMISSION (open access)

CHARACTERIZATION OF AN ADVANCED GADOLINIUM NEUTRON ABSORBER ALLOY BY MEANS OF NEUTRON TRANSMISSION

Neutron transmission experiments were performed on samples of an advanced nickel-chromium-molybdenum-gadolinium (Ni-Cr-Mo-Gd) neutron absorber alloy. The primary purpose of the experiments was to demonstrate the thermal neutron absorbing capability of the alloy at specific gadolinium dopant levels. The new alloy is to be deployed for criticality control of highly enriched DOE SNF. For the transmission experiments, alloy test samples were fabricated with 0.0, 1.58 and 2.1 wt% natural gadolinium dispersed in a Ni-Cr-Mo base alloy. The transmission experiments were successfully carried out at the Los Alamos Neutron Science Center (LANSCE). Measured data from the neutron transmission experiments were compared to calculated results derived from a simple exponential transmission formula using only radiative capture cross sections. Excellent agreement between the measured and calculated results demonstrated the expected strong thermal absorption capability of the gadolinium poison and in addition, verified the measured elemental composition of the alloy test samples. The good agreement also indirectly confirmed that the gadolinium was dispersed fairly uniformly in the alloy and the ENDF VII radiative capture cross section data were accurate.
Date: September 1, 2007
Creator: Wachs, Gregg W.
System: The UNT Digital Library
Charged-Current Interaction Measurements in MiniBooNE (open access)

Charged-Current Interaction Measurements in MiniBooNE

Neutrino oscillation is the only known phenomenon for physics beyond the standard model. To investigate this phenomenon, the understanding of low energy neutrino scattering (200<E<2000 MeV) is the crucial task for high energy physicists. In this energy region, the charged current quasi-elastic (CCQE) neutrino interaction is the dominant process, and experiments require a precise model to predict signal samples. Using a high-statistics sample of muon neutrino CCQE events, MiniBooNE finds that a simple Fermi gas model, with appropriate adjustments, accurately characterizes the CCQE events on carbon. The extracted parameters include an effective axial mass, MA=1.23 {+-} 0.20 GeV, and a Pauli-blocking parameter, kappa = 1.019 {+-} 0.011.
Date: September 1, 2007
Creator: Katori, Teppei
System: The UNT Digital Library
Clean-in-Place and Reliability Testing of a Commercial 12.5-cm Annular Centrifugal Contactor at the INL (open access)

Clean-in-Place and Reliability Testing of a Commercial 12.5-cm Annular Centrifugal Contactor at the INL

The renewed interest in advancing nuclear energy has spawned the research of advanced technologies for recycling nuclear fuel. A significant portion of the advanced fuel cycle includes the recovery of selected actinides by solvent extraction methods utilizing centrifugal contactors. Although the use of centrifugal contactors for solvent extraction is widely known, their operation is not without challenges. Solutions generated from spent fuel dissolution contain unknown quantities of undissolved solids. A majority of these solids will be removed via various methods of filtration. However, smaller particles are expected to carry through to downstream solvent extraction processes and equipment. In addition, solids/precipitates brought about by mechanical or chemical upsets are another potential area of concern. During processing, particulate captured in the rotor assembly by high centrifugal forces eventually forms a cake-like structure on the inner wall introducing balance problems and negatively affecting phase separations. One of the features recently developed for larger engineering scale Annular Centrifugal Contactors (ACCs) is the Clean-In-Place (CIP) capability. Engineered spray nozzles were installed into the hollow central rotor shaft in all four quadrants of the rotor assembly. This arrangement allows for a very convenient and effective method of solids removal from within the rotor assembly.
Date: September 1, 2007
Creator: Mann, N. R.; Garn, T. G.; Meikrantz, D. H.; Law, J. D. & Todd, T. A.
System: The UNT Digital Library
Clean-in-Place and Reliability Testing of a Commercial 12.5 cm Annular Centrifugal Contactor at the INL (open access)

Clean-in-Place and Reliability Testing of a Commercial 12.5 cm Annular Centrifugal Contactor at the INL

The renewed interest in advancing nuclear energy has spawned the research of advanced technologies for recycling nuclear fuel. A significant portion of the advanced fuel cycle includes the recovery of selected actinides by solvent extraction methods utilizing centrifugal contactors. Although the use of centrifugal contactors for solvent extraction is widely known, their operation is not without challenges. Solutions generated from spent fuel dissolution contain unknown quantities of undissolved solids. A majority of these solids will be removed via various methods of filtration. However, smaller particles are expected to carry through to downstream solvent extraction processes and equipment. In addition, solids/precipitates brought about by mechanical or chemical upsets are another potential area of concern. During processing, particulate captured in the rotor assembly by high centrifugal forces eventually forms a cake-like structure on the inner wall introducing balance problems and negatively affecting phase separations. One of the features recently developed for larger engineering scale Annular Centrifugal Contactors (ACCs) is the Clean-In-Place (CIP) capability. Engineered spray nozzles were installed into the hollow central rotor shaft in all four quadrants of the rotor assembly. This arrangement allows for a very convenient and effective method of solids removal from within the rotor assembly.
Date: September 1, 2007
Creator: Mann, N. R.; Garn, T. G.; Meikrantz, D. H.; Law, J. D. & Todd, T. A.
System: The UNT Digital Library
Clustering properties of ultrahigh energy cosmic rays and the search for their astrophysical sources (open access)

Clustering properties of ultrahigh energy cosmic rays and the search for their astrophysical sources

The arrival directions of ultrahigh energy cosmic rays (UHECRs) may show anisotropies on all scales, from just above the experimental angular resolution up to medium scales and dipole anisotropies. We find that a global comparison of the two-point auto-correlation function of the data with the one of catalogues of potential sources is a powerful diagnostic tool. In particular, this method is far less sensitive to unknown deflections in magnetic fields than cross-correlation studies while keeping a strong discrimination power among source candidates. We illustrate these advantages by considering ordinary galaxies, gamma ray bursts and active galactic nuclei as possible sources. Already the sparse publicly available data suggest that the sources of UHECRs may be a strongly clustered sub-sample of galaxies or of active galactic nuclei. We present forecasts for various cases of source distributions which can be checked soon by the Pierre Auger Observatory.
Date: September 1, 2007
Creator: Cuoco, Alessandro; Hannestad, Steen; Haugboelle, Troels; U., /Aarhus; Kachelriess, Michael; Tech., /Norwegian U. Sci. et al.
System: The UNT Digital Library
CO2-selective, Hybrid Membranes by Silation of Alumina (open access)

CO2-selective, Hybrid Membranes by Silation of Alumina

Hybrid membranes are feasible candidates for the separation of CO2 from gas produced in coal-based power generation since they have the potential to combine the high selectivity of polymer membranes and the high permeability of inorganic membranes. An interesting method for producing hybrid membranes is the silation of an inorganic membrane. In this method, trichloro- or alkoxy-silanes interact with hydroxyl groups on the surface of γ-AlO3 or TiO2, binding organic groups to that surface. By varying the length of these organic groups on the organosilane, it should be possible to tailor the effective pore size of the membrane. Similarly, the addition of “CO2-phillic” groups to the silating agent allows for the careful control of surface affinity and the enhancement of surface diffusion mechanisms. This method of producing hybrid membranes selective to CO2 was first attempted by Hyun [1] who silated TiO2 with phenyltriethoxysilane. Later, Way [2] silated γ-AlO3 with octadecyltrichlorosilane. Both researchers were successful in producing membranes with improved selectivity toward CO2, but permeability was not maintained at a commercially applicable level. XPS data indicated that the silating agent did not penetrate into the membrane pores and separation actually occurred in a thin “polymer-like” surface layer. The present study attempts …
Date: September 1, 2007
Creator: Luebke, D. R. & Pennline, H. W.
System: The UNT Digital Library
A Complete Scheme for a Muon Collider. (open access)

A Complete Scheme for a Muon Collider.

A complete scheme for production, cooling, acceleration, and ring for a 1.5 TeV center of mass muon collider is presented, together with parameters for two higher energy machines. The schemes starts with the front end of a proposed neutrino factory that yields bunch trains of both muon signs. Six dimensional cooling in long-period helical lattices reduces the longitudinal emittance until it becomes possible to merge the trains into single bunches, one of each sign. Further cooling in all dimensions is applied to the single bunches in further helical lattices. Final transverse cooling to the required parameters is achieved in 50 T solenoids.
Date: September 1, 2007
Creator: Palmer, R. B.; Berg, J. S.; Fernow, R. C.; Gallardo, J. C.; Kirk, H. G.; Alexahin, Y. et al.
System: The UNT Digital Library
Cooling in a compound bucket (open access)

Cooling in a compound bucket

Electron cooling in the Fermilab Recycler ring is found to create correlation between longitudinal and transverse tails of the antiproton distribution. By separating the core of the beam from the tail and cooling the tail using 'gated' stochastic cooling while applying electron cooling on the entire beam, one may be able to significantly increase the overall cooling rate. In this paper, we describe the procedure and first experimental results.
Date: September 1, 2007
Creator: Shemyakin, A.; Bhat, C.; Broemmelsiek, D.; Burov, A.; Hu, M. & /Fermilab
System: The UNT Digital Library
A Critical Review of Wind Transmission Cost Estimates From Majortransmission Planning Efforts (open access)

A Critical Review of Wind Transmission Cost Estimates From Majortransmission Planning Efforts

It is difficult to evaluate the cost of new transmission for wind energy due to the complex and data intensive process of transmission planning. The requirement for wind to be sited in high wing resource areas that are often far from load centers and the low capacity factor of individual wind farms leads to concerns that transmission for wind may have excessive costs. However, regional transmission planning groups are increasinglu including wind energy in transmission plans. We analyze 17 transmissions pans that include between 500 MW and 25.5 GW of new wind generation to evaluate the range of expected unit costs of transmission for wind. Based on a simplified methodology we find that transmission for wind ranges from $0.40 to 95/MWh or $8.5 to $1,940/kW. However, nearly 75% of the scenarios studied cost less than around $20/MWh or $420/kW. We find no correlation between the unit cost of transmission and the amount of new wind analyzed in each scenario. We also find that no uniform set of methods and assumptions has emerged for evaluating the transmission requirements for wind energy.
Date: September 1, 2007
Creator: Mills, Andrew; Wiser, Ryan & Porter, Kevin
System: The UNT Digital Library
Deploying perfSONAR-based End-2-End Monitoring for Production US CMS Networking (open access)

Deploying perfSONAR-based End-2-End Monitoring for Production US CMS Networking

Fermilab is the US Tier-1 Center for CMS data storage and analysis. End-2-End (E2E) circuits are utilized to support high impact data movement into and out of the Tier-1 Center. E2E circuits have been implemented to facilitate the movement of raw experiment data from the Tier-0 Center at CERN, as well as processed data to a number of the US Tier-2 sites. Troubleshooting and monitoring of those circuits presents a significant challenge, since the circuits typically cross multiple research & education networks, each with its own management domain and customized monitoring capabilities. The perfSONAR Monitoring Project was established to facilitate development and deployment of a common monitoring infrastructure across multiple network management domains. Fermilab has deployed perfSONAR across its E2E circuit infrastructure and enhanced the product with several tools that ease the monitoring and management of those circuits. This paper will present the current state of perfSONAR monitoring at Fermilab and detail our experiences using perfSONAR to manage our current E2E circuit infrastructure. We will describe how production network circuits are monitored by perfSONAR E2E Monitoring Points (MPs), and the benefits it has brought to production US CMS networking support.
Date: September 1, 2007
Creator: Grigoriev, Maxim; Bobyshev, Andrey; Crawford, Matt; DeMar, Phil; Grigaliunas, Vyto & Petravick, Don
System: The UNT Digital Library
Design and Implementation of the New D0 Level-1 Calorimeter Trigger (open access)

Design and Implementation of the New D0 Level-1 Calorimeter Trigger

Increasing luminosity at the Fermilab Tevatron collider has led the D0 collaboration to make improvements to its detector beyond those already in place for Run IIa, which began in March 2001. One of the cornerstones of this Run IIb upgrade is a completely redesigned level-1 calorimeter trigger system. The new system employs novel architecture and algorithms to retain high efficiency for interesting events while substantially increasing rejection of background. We describe the design and implementation of the new level-1 calorimeter trigger hardware and discuss its performance during Run IIb data taking. In addition to strengthening the physics capabilities of D0, this trigger system will provide valuable insight into the operation of analogous devices to be used at LHC experiments.
Date: September 1, 2007
Creator: Abolins, M.; Adams, M.; Adams, T.; Aguilo, E.; Anderson, J.; Bagby, L. et al.
System: The UNT Digital Library
Development and Validation of WECC Variable Speed Wind Turbine Dynamic Models for Grid Integration Studies (open access)

Development and Validation of WECC Variable Speed Wind Turbine Dynamic Models for Grid Integration Studies

This paper describes reduced-order, simplified wind turbine models for analyzing the stability impact of large arrays of wind turbines with a single point of network interconnection.
Date: September 1, 2007
Creator: Behnke, M.; Ellis, A.; Kazachkov, Y.; McCoy, T.; Muljadi, E.; Price, W. et al.
System: The UNT Digital Library
Development of a fiber coupled, end pumped, Nd:YAG laser spark plug (open access)

Development of a fiber coupled, end pumped, Nd:YAG laser spark plug

None
Date: September 1, 2007
Creator: Woodruff, S. D. & McIntyre, D. L.
System: The UNT Digital Library
DIAMIDE DERIVATIVES OF DIPICOLINIC ACID AS ACTINIDE AND LANTHANIDE EXTRACTANTS IN A VARIATION OF THE UNEX PROCESS (open access)

DIAMIDE DERIVATIVES OF DIPICOLINIC ACID AS ACTINIDE AND LANTHANIDE EXTRACTANTS IN A VARIATION OF THE UNEX PROCESS

The Universal Extraction (UNEX) process has been developed for simultaneous extraction of cesium, strontium, and actinides from acidic solutions. This process utilizes an extractant consisting of 0.08 M chlorinated cobalt dicarbollide (HCCD), 0.007-0.02 M polyethylene glycol (PEG-400), and 0.02 M diphenyl-N,N-di-n-butylcarbamoylmethylphosphine oxide (Ph2CMPO) in the diluent trifluoromethylphenyl sulfone (CF3C6H5SO2, designated FS-13) and provides simultaneous extraction of Cs, Sr, actinides, and lanthanides from HNO3 solutions. The UNEX process is of limited utility for processing acidic solutions containing large quantities of lanthanides and/or actinides, such as dissolved spent nuclear fuel solutions. These constraints are primarily attributed to the limited concentrations of CMPO (a maximum of ~0.02 M) in the organic phase and limited solubility of the CMPO-metal complexes. As a result, alternative actinide and lanthanide extractants are being investigated for use with HCCD as an improvement for waste processing and for applications where higher concentrations of the metals are present. Our preliminary results indicate that diamide derivatives of dipicolinic acid may function as efficient actinide and lanthanide extractants. The results to be presented indicate that, of the numerous diamides studied to date, the tetrabutyldiamide of dipicolinic acid, TBDPA, shows the most promise as an alternative actinide/lanthanide extractant in the UNEX process.
Date: September 1, 2007
Creator: Peterman, D. R.; Herbst, R. S.; Law, J. D.; Tillotson, R. D.; Garn, T. G.; Todd, T. A. et al.
System: The UNT Digital Library
Direct Assay of Filter Media following DEOX Testing (open access)

Direct Assay of Filter Media following DEOX Testing

The direct assay of filter media by gamma spectrometry following DEOX testing has distinct advantages over analytical chemistry. Prior to using gamma spectrometry for the quantification of cesium (Cs-137), a calibration must be established with known sources since gamma spectrometry yields relative results. Quantitative analytical chemistry, in particular ICP-MS, has been performed on the filter media for comparison to the gamma spectrometry data. The correlation of gamma spectrometry to ICP-MS data is presented to justify the continued use of gamma spectrometry for filter media.
Date: September 1, 2007
Creator: Lind, R. P.; Giglio, J. J.; Cummings, D. G.; Huntley, M. W.; Morgan, C. D.; Bateman, K. J. et al.
System: The UNT Digital Library
DZero data-intensive computing on the Open Science Grid (open access)

DZero data-intensive computing on the Open Science Grid

High energy physics experiments periodically reprocess data, in order to take advantage of improved understanding of the detector and the data processing code. Between February and May 2007, the DZero experiment has reprocessed a substantial fraction of its dataset. This consists of half a billion events, corresponding to about 100 TB of data, organized in 300,000 files. The activity utilized resources from sites around the world, including a dozen sites participating to the Open Science Grid consortium (OSG). About 1,500 jobs were run every day across the OSG, consuming and producing hundreds of Gigabytes of data. Access to OSG computing and storage resources was coordinated by the SAM-Grid system. This system organized job access to a complex topology of data queues and job scheduling to clusters, using a SAM-Grid to OSG job forwarding infrastructure. For the first time in the lifetime of the experiment, a data intensive production activity was managed on a general purpose grid, such as OSG. This paper describes the implications of using OSG, where all resources are granted following an opportunistic model, the challenges of operating a data intensive activity over such large computing infrastructure, and the lessons learned throughout the project.
Date: September 1, 2007
Creator: Abbott, B.; U., /Oklahoma; Baranovski, A.; Diesburg, M.; Garzoglio, G.; /Fermilab et al.
System: The UNT Digital Library