28 research outputs found
AMANDA Observations Constrain the Ultra-High Energy Neutrino Flux
A number of experimental techniques are currently being deployed in an effort
to make the first detection of ultra-high energy cosmic neutrinos. To
accomplish this goal, techniques using radio and acoustic detectors are being
developed, which are optimally designed for studying neutrinos with energies in
the PeV-EeV range and above. Data from the AMANDA experiment, in contrast, has
been used to place limits on the cosmic neutrino flux at less extreme energies
(up to ~10 PeV). In this letter, we show that by adopting a different analysis
strategy, optimized for much higher energy neutrinos, the same AMANDA data can
be used to place a limit competitive with radio techniques at EeV energies. We
also discuss the sensitivity of the IceCube experiment, in various stages of
deployment, to ultra-high energy neutrinos.Comment: 4 pages, 3 figure
Operation Of The NuMi Beam Monitoring System
The NuMI (Neutrinos at the Main Injector) facility produces an intense neutrino beam for experiments. The NuMI Beam Monitoring system consists of four arrays of ion chambers that measure the intensity and distribution of the remnant hadron and tertiary muon beams produced in association with the neutrinos. The ion chambers operate in an environment of high particle fluxes and high radiation.Physic
Report of the 2005 Snowmass Top/QCD Working Group
This report discusses several topics in both top quark physics and QCD at an
International Linear Collider (ILC). Issues such as measurements at the
threshold, including both theoretical and machine requirements, and
the determination of electroweak top quark couplings, are reviewed. New results
concerning the potential of a 500 GeV collider for measuring
couplings and the top quark Yukawa coupling are presented. The status of higher
order QCD corrections to jet production cross sections, heavy quark form
factors, and longitudinal gauge boson scattering, needed for percent-level
studies at the ILC, are reviewed. A new study of the measurement of the
hadronic structure of the photon at a collider is presented. The
effects on top quark properties from several models of new physics, including
composite models, Little Higgs theories, and CPT violation, are studied.Comment: 39 pages, many figs; typos fixed and refs added. Contributed to the
2005 International Linear Collider Physics and Detector Workshop and 2nd ILC
Accelerator Workshop, Snowmass, Colorado, 14-27 Aug 200
Pulsed Energy Storage System Design
A superconductive energy storage magnet which is connected to the three phase power system could be designed, constructed, and placed in operation at Fermilab which would essentially eliminate the large repetitive power pulses now required from the power system. In addition to the power pulses, voltage flicker is also caused due to the reactive power pulsation. Specifically, a one megawatt hour superconductive energy storage magnet and a 2.00 megawatt thyristorized converter can achieve nullification of these power pulses up to 400 GEV synchrotron operation. Above 400 GEV, operation should be possible up to 500 GEV with appreciable less power pulsing requirements from the system than are now considered permissible. Carried to successful completion, this project would serve to advance applied superconductivity to a highly significant degree. The effect would be of world wide importance to both high energy physics and to the electric power industry. The preliminary magnet design is a 1 MWh dipole composed of cryogenically stable composite conductors connected in parallel with aluminum shield windings. The shield windings carry impressed pulsed currents while eliminating pulsed currents from the dc superconductive windings. Without pulsed currents or pulsed magnetic fields there are no ac losses in standard helium. The major radius of the dipole is 8.85 m; the minor radius is 0.69m; there are 188 turns at 80,000 A and each turn is 4 conductors wound in parallel. The 20,000 A TiNb-copper composite conductor is l0x 1.12 cm in cross section similar to but larger than the FNAL bubble chamber conductor. The shield is 188 turns (equal number of turns is a shielding condition) of hollow aluminum conductor cooled via circulated cold helium gas at 40K. The turns are spaced around the minor circumference according to a cosine distribution which produces zero internal field. In use the shield loss converted to room temperature power is about .8MW when 0.1 MWh is used from a 1 MWh storage dipole. The 0.1 MWh is sufficient to provide complete load leveling for 400 GEV pulses, and operation at 500 GEV with lower power transients than are presently experienced
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Scalability and interoperability within glideinWMS
Physicists have access to thousands of CPUs in grid federations such as OSG and EGEE. With the start-up of the LHC, it is essential for individuals or groups of users to wrap together available resources from multiple sites across multiple grids under a higher user-controlled layer in order to provide a homogeneous pool of available resources. One such system is glideinWMS, which is based on the Condor batch system. A general discussion of glideinWMS can be found elsewhere. Here, we focus on recent advances in extending its reach: scalability and integration of heterogeneous compute elements. We demonstrate that the new developments exceed the design goal of over 10,000 simultaneous running jobs under a single Condor schedd, using strong security protocols across global networks, and sustaining a steady-state job completion rate of a few Hz. We also show interoperability across heterogeneous computing elements achieved using client-side methods. We discuss this technique and the challenges in direct access to NorduGrid and CREAM compute elements, in addition to Globus based systems
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Exotic neutrino interactions at the Pierre Auger Observatory
The Pierre Auger Observatory for cosmic rays provides a laboratory for studying fundamental interactions at energies well beyond those available at colliders. In addition to hadrons or photons, Auger is sensitive to ultra-high energy neutrinos in the cosmic radiation and models for new physics can be explored by observing neutrino interactions at center-of-mass energies beyond the TeV scale. By comparing the rate for quasi-horizontal, deeply penetrating air showers triggered by all types of neutrinos with the rate for slightly upgoing showers generated by Earth-skimming tau neutrinos, any deviation of the neutrino-nucleon cross-section from the Standard Model expectation can be constrained. We show that this can test models of low-scale quantum gravity (including processes such as Kaluza-Klein graviton exchange, microscopic black hole production and string resonances), as well as non-perturbative electroweak instanton mediated processes. Moreover, the observed ratios of neutrino flavors would severely constrain the possibility of neutrino decay
The pilot way to Grid resources using glideinWMS
Grid computing has become very popular in big and widespread scientific communities with high computing demands, like high energy physics. Computing resources are being distributed over many independent sites with only a thin layer of Grid middleware shared between them. This deployment model has proven to be very convenient for computing resource providers, but has introduced several problems for the users of the system, the three major being the complexity of job scheduling, the nonuniformity of computer resources, and the lack of good job monitoring. Pilot jobs address all the above problems by creating a virtual private computing pool on top of Grid resources. This paper presents both the general pilot concept, as well as a concrete implementation, called glideinWMS, deployed in the Open Science Grid
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Use of glide-ins in CMS for production and analysis
With the evolution of various grid federations, the Condor glide-ins represent a key feature in providing a homogeneous pool of resources using late-binding technology. The CMS collaboration uses the glide-in based Workload Management System, glideinWMS, for production (ProdAgent) and distributed analysis (CRAB) of the data. The Condor glide-in daemons traverse to the worker nodes, submitted via Condor-G. Once activated, they preserve the Master-Worker relationships, with the worker first validating the execution environment on the worker node before pulling the jobs sequentially until the expiry of their lifetimes. The combination of late-binding and validation significantly reduces the overall failure rate visible to CMS physicists. We discuss the extensive use of the glideinWMS since the computing challenge, CCRC-08, in order to prepare for the forthcoming LHC data-taking period. The key features essential to the success of large-scale production and analysis on CMS resources across major grid federations, including EGEE, OSG and NorduGrid are outlined. Use of glide-ins via the CRAB server mechanism and ProdAgent, as well as first hand experience of using the next generation CREAM computing element within the CMS framework is discussed
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