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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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At least 19 records

Extending the Fermi -LAT data processing pipeline to the grid

The Data Handling Pipeline ("Pipeline") has been developed for the Fermi Gamma-Ray Space Telescope (Fermi) Large Area Telescope (LAT) which launched in June 2008. Since then it has been in use to completely automate the production of data quality monitoring quantities, reconstruction and routine analysis of all data received from the satellite and to deliver science products to the collaboration and the Fermi Science Support Center. Aside from the reconstruction of raw data from the satellite (Level 1), data reprocessing and various event-level analyses are also reasonably heavy loads on the pipeline and computing resources. These other loads, unlike Level 1, can run continuously for weeks or months at a time. Additionally, it receives heavy use in performing production Monte Carlo tasks.

ASTRO↗

First Experiences with LHC Grid Computing and Distributed Analysis

In this presentation the experiences of the LHC experiments using grid computing were presented with a focus on experience with distributed analysis. After many years of development, preparation, exercises, and validation the LHC (Large Hadron Collider) experiments are in operations. The computing infrastructure has been heavily utilized in the first 6 months of data collection. The general experience of exploiting the grid infrastructure for organized processing and preparation is described, as well as the successes employing the infrastructure for distributed analysis. At the end the expected evolution and future plans are outlined.

99 GENERAL AND MISCELLANEOUS↗

Arachne - A web-based event viewer for MINERvA

Neutrino interaction events in the MINERvA detector are visually represented with a web-based tool called Arachne. Data are retrieved from a central server via AJAX, and client-side JavaScript draws images into the user's browser window using the draft HTML 5 standard. These technologies allow neutrino interactions to be viewed by anyone with a web browser, allowing for easy hand-scanning of particle interactions. Arachne has been used in MINERvA to evaluate neutrino data in a prototype detector, to tune reconstruction algorithms, and for public outreach and education.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Data Preservation in High Energy Physics

Data from high-energy physics (HEP) experiments are collected with significant financial and human effort and are mostly unique. At the same time, HEP has no coherent strategy for data preservation and re-use. An inter-experimental Study Group on HEP data preservation and long-term analysis was convened at the end of 2008 and held two workshops, at DESY (January 2009) and SLAC (May 2009). This document is an intermediate report to the International Committee for Future Accelerators (ICFA) of the reflections of this Study Group. Large data sets accumulated during many years of detector operation at particle accelerators are the heritage of experimental HEP. These data sets offer unique opportunities for future scientific studies, sometimes long after the shut-down of the actual experiments: new theoretical input; new experimental results and analysis techniques; the quest for high-sensitivity combined analyses; the necessity of cross checks. In many cases, HEP data sets are unique; they cannot and most likely will not be superseded by data from newer generations of experiments. Once lost, or in an unusable state, HEP data samples cannot be reasonably recovered. The cost of conserving this heritage through a collaborative, target-oriented long-term data preservation program would be small, compared to the costs of past experimental projects or to the efforts to re-do experiments. However, this cost is not negligible, especially for collaborations close or past their end-date. The preservation of HEP data would provide today's collaborations with a secure way to complete their data analysis and enable them to seize new scientific opportunities in the coming years. The HEP community will benefit from preserved data samples through reanalysis, combination, education and outreach. Funding agencies would receive more scientific return, and a positive image, from their initial investment leading to the production and the first analysis of preserved data.

43 PARTICLE ACCELERATORS↗

Status Report of the DPHEP Study Group: Towards a Global Effort for Sustainable Data Preservation in High Energy Physics

Data from high-energy physics (HEP) experiments are collected with significant financial and human effort and are mostly unique. An inter-experimental study group on HEP data preservation and long-term analysis was convened as a panel of the International Committee for Future Accelerators (ICFA). The group was formed by large collider-based experiments and investigated the technical and organisational aspects of HEP data preservation. An intermediate report was released in November 2009 addressing the general issues of data preservation in HEP. This paper includes and extends the intermediate report. It provides an analysis of the research case for data preservation and a detailed description of the various projects at experiment, laboratory and international levels. In addition, the paper provides a concrete proposal for an international organisation in charge of the data management and policies in high-energy physics.

Computing, Experiment-HEP,COMP, HEPEX↗

Improved WIMP-search reach of the CDMS II germanium data

CDMS II data from the five-tower runs at the Soudan Underground Laboratory were reprocessed with an improved charge-pulse fitting algorithm. Two new analysis techniques to reject surface-event backgrounds were applied to the 612 kg days germanium-detector weakly interacting massive particle (WIMP)-search exposure. An extended analysis was also completed by decreasing the 10 keV analysis threshold to ~5 keV, to increase sensitivity near a WIMP mass of 8 GeV/c 2 . After unblinding, there were zero candidate events above a deposited energy of 10 keV and six events in the lower-threshold analysis. This yielded minimum WIMP-nucleon spin-independent scattering cross-section limits of 1.8×10 –44 and 1.18×10 –41 at 90% confidence for 60 and 8.6 GeV/c 2 WIMPs, respectively. This improves the previous CDMS II result by a factor of 2.4 (2.7) for 60 (8.6) GeV/c 2 WIMPs.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗

Sloan Digital Sky Survey Photometric Calibration Revisited

The Sloan Digital Sky Survey calibration is revisited to obtain the most accurate photometric calibration. A small but significant error is found in the flat-fielding of the Photometric telescope used for calibration. Two SDSS star catalogs are compared and the average difference in magnitude as a function of right ascension and declination exhibits small systematic errors in relative calibration. The photometric transformation from the SDSS Photometric Telescope to the 2.5 m telescope is recomputed and compared to synthetic magnitudes computed from measured filter bandpasses.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

Measurement of the E+ E- to Pi+ Pi- (Gamma) Cross Section with the ISR Method with BaBar

A precision measurement of the cross section for the process e{sup +}e{sup -} {yields} {pi}{sup +}{pi}{sup -}({gamma}) is presented with the radiative return method with the high statistics data accumulated by BaBar at the {Upsilon}(4S). The luminosity is determined from the study of the corresponding leptonic process e{sup +}e{sup -} {yields} {mu}{sup +}{mu}{sup -}({gamma}), thus cancelling several factors and reducing the overall systematic uncertainty. Trigger, tracking, particle identification, and kinematic-fit {chi}{sup 2} efficiencies are evaluated from data in the same environment. Additional radiation from the initial and the final states is studied in both processes. The analysis covers the mass range between threshold and 5 GeV. Preliminary results are presented here between 0.5 and 3 GeV, with data samples of 513183 pion events and 445631 muon events. The systematic uncertainty in the main {rho} resonance region is 5.6 x 10{sup -3}. The measured mass dependent pion-pair cross section is compared with measurements from earlier experiments and used to compute the hadronic vacuum polarization contribution from the dominant {pi}{pi} channel to the muon magnetic anomaly.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

The MINER$\nu$A Data Acquisition System and Infrastructure

MINERvA (Main INjector ExpeRiment v-A) is a new few-GeV neutrino cross-section experiment that began taking data in the FNAL NuMI (Fermi National Accelerator Laboratory Neutrinos at the Main Injector) beam-line in March of 2010. MINERvA employs a fine-grained scintillator detector capable of complete kinematic characterization of neutrino interactions. This paper describes the MINERvA data acquisition system (DAQ) including the readout electronics, software, and computing architecture.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

B Decay and CP Violation: CKM Angles and Sides at the BABAR and BELLE B-Factories

A remarkable success has been achieved by the B-Factories, going beyond expectation in some field, like the measurement of {gamma}. BABAR has now finished its data taking, leaving BELLE alone in the 'race', but still many analyses are going on. The CKM UT is constrained by both measurements of CP-conserving and CP-violating quantities, leading to a picture of the CKM sector consistent with the SM. Measurements of semi-leptonic decays benefit from improving experimental techniques and more precise theoretical computations. The angle {beta} is a precision measurement, reaching accuracy of SM calculation. The angle {alpha} will ultimatly be limited by penguin pollution. The measurement of {gamma} is reaching the 13{sup o} precision.

54 ENVIRONMENTAL SCIENCES↗

Recent Results on Semileptonic Decays at Babar

Some recent BABAR results on semileptonic decays are presented. They focus on the determination of the CKM matrix elements |V{sub ub}| and |V{sub cb}| in inclusive and exclusive b {yields} u{ell}v and b {yields} c{ell}v decays, and on form factors measurement in exclusive c {yields} s{ell}v decays. Semileptonic decays play a crucial role in the determination of the unitarity triangle parameters: decays of the b quark give access to the CKM matrix elements |V{sub ub}| and |V{sub cb}|, while charm decays provide a way to validate lattice QCD computations through form factors measurements. Such calculations provide theoretical inputs that are used, especially, in the b sector. A lot of new results have been obtained by the BABAR collaboration during the last years, thanks to the large b{bar b} and c{bar c} production cross-sections and to the large recorded statistics. Some of these measurements are presented here.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗

Search for a Standard Model Higgs Boson with a Dilepton and Missing Energy Signature

The subject of this thesis is the search for a standard model Higgs boson decaying to a pair of W bosons that in turn decay leptonically, H → W + W - → $\bar{ℓ}$vℓ$\bar{v}$. This search is performed considering events produced in p$\bar{p}$ collisions at √s = 1.96 TeV, where two oppositely charged lepton candidates (e + e - , e ± μ ± , or μ + μ} - ), and missing transverse energy, have been reconstructed. The data were collected with the D0 detector at the Fermilab Tevatron collider, and are tested against the standard model predictions computed for a Higgs boson with mass in the range 115-200 GeV. No excess of events over background is observed, and limits on Standard Model Higgs boson production are determined. An interpretation of these limits within the hypothesis of a fourth-generation extension to the standard model is also given. The overall analysis scheme is the same for the three dilepton pairs being considered (e + e - , e ± μ ± , or μ + μ - ); this thesis, however, describes in detail the study of the dimuon final state.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Combined CDF and D0 Searches for the Standard Model Higgs Boson Decaying to Two Photons with up to 8.2 fb^-1

We combine results from CDF and D0's direct searches for the standard model (SM) Higgs boson (H) produced in p{bar p} collisions at the Fermilab Tevatron at {radical}s = 1.96 TeV, focusing on the decay H {yields} {gamma}{gamma}. We compute upper limits on the Higgs boson production cross section times the decay branching fraction in the range 100 < m{sub H} < 150 GeV/c{sup 2}, and we interpret the results in the context of the standard model. We use the MSTW08 parton distribution functions and the latest theoretical cross section predictions when testing for the presence of a SM Higgs boson. With datasets corresponding to 7.0 fb{sup -1} (CDF) and 8.2 fb{sup -1} (D0), the 95% C.L. upper limits on Higgs boson production is a factor of 10.5 times the SM cross section for a Higgs boson mass of 115 GeV/c{sup 2}.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Dark matter effective field theory scattering in direct detection experiments

We examine the consequences of the effective field theory (EFT) of dark matter–nucleon scattering for current and proposed direct detection experiments. Exclusion limits on EFT coupling constants computed using the optimum interval method are presented for SuperCDMS Soudan, CDMS II, and LUX, and the necessity of combining results from multiple experiments in order to determine dark matter parameters is discussed. We demonstrate that spectral differences between the standard dark matter model and a general EFT interaction can produce a bias when calculating exclusion limits and when developing signal models for likelihood and machine learning techniques. We also discuss the implications of the EFT for the next-generation (G2) direct detection experiments and point out regions of complementarity in the EFT parameter space.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗

Model Independent Bounds on Kinetic Mixing

New Abelian vector bosons can kinetically mix with the hypercharge gauge boson of the Standard Model. This letter computes the model independent limits on vector bosons with masses from 1 GeV to 1 TeV. The limits arise from the numerous e{sup +}e{sup -} experiments that have been performed in this energy range and bound the kinetic mixing by {epsilon} {approx}< 0.03 for most of the mass range studied, regardless of any additional interactions that the new vector boson may have.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗