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  1. Multiple Independent File Parallel I/O with HDF5

    The HDF5 library has supported the I/O requirements of HPC codes at Lawrence Livermore National Labs (LLNL) since the late 90’s. In particular, HDF5 used in the Multiple Independent File (MIF) parallel I/O paradigm has supported LLNL code’s scalable I/O requirements and has recently been gainfully used at scales as large as O(10 6) parallel tasks.
  2. Pyroprocessing Monitoring Technology Development at Idaho National Laboratory

    The Idaho National Laboratory (INL), with support from the U.S. Department of Energy, Office of Nuclear Energy, Nuclear Technology Research and Development program, has been developing advanced instrumentation and approaches for enhancing the effectiveness of nuclear material control and accounting for future reprocessing facilities with particular emphasis on pyroprocessing. Advanced modeling capabilities augment new instrumentation development, predict material flows, integrate process monitoring data, and assess overall system effectiveness of the safeguards and security system. In this paper we provide a brief overview of the Safeguards and Security by Design approach being pursued under the program and details of advanced processmore » monitoring instrumentation under development at the INL, which includes a triple bubbler system for on-line monitoring of level and density of molten salt, sensors for monitoring actinide concentrations in molten salt, and thermal-couple instrumentation for near real time determination of Pu content in U/TRU ingots. Laboratory and field testing data will be presented, as well as integration of these sensors into a concept for utilization of process monitoring information in concert with traditional nuclear material accountancy data.« less
  3. Search for Neutrinoless Double- β Decay in Ge 76 with the Majorana Demonstrator

    The Majorana Collaboration is operating an array of high purity Ge detectors to search for neutrinoless double-β decay in 76Ge. The Majorana Demonstrator comprises 44.1 kg of Ge detectors (29.7 kg enriched in 76Ge) split between two modules contained in a low background shield at the Sanford Underground Research Facility in Lead, South Dakota. In this paper, we present results from data taken during construction, commissioning, and the start of full operations. We achieve unprecedented energy resolution of 2.5 keV FWHM at Q ββ and a very low background with no observed candidate events in 9.95 kg yr of enriched Ge exposure, resulting in a lower limit on the half-life of 1.9 × 10 25 yr (90% C.L.). This result constrains the effective Majorana neutrino mass to below 240-520 meV, depending on the matrix elements used. In our experimental configuration with the lowest background, the background is 4.0more » $$+3.1\atop{-2.5}$$ counts/(FWHM t yr).« less
  4. Multi-Purpose, Application-Centric, Scalable I/O Proxy Application

    MACSio is a Multi-purpose, Application-Centric, Scalable I/O proxy application. It is designed to support a number of goals with respect to parallel I/O performance testing and benchmarking including the ability to test and compare various I/O libraries and I/O paradigms, to predict scalable performance of real applications and to help identify where improvements in I/O performance can be made within the HPC I/O software stack.
  5. Search for neutron-antineutron oscillations at the Sudbury Neutrino Observatory

    Tests on B–L symmetry breaking models are important probes to search for new physics. One proposed model with Δ(B–L)=2 involves the oscillations of a neutron to an antineutron. In this paper, a new limit on this process is derived for the data acquired from all three operational phases of the Sudbury Neutrino Observatory experiment. The search concentrated on oscillations occurring within the deuteron, and 23 events were observed against a background expectation of 30.5 events. These translated to a lower limit on the nuclear lifetime of 1.48 × 10 31 yr at 90% C.L. when no restriction was placed onmore » the signal likelihood space (unbounded). Alternatively, a lower limit on the nuclear lifetime was found to be 1.18 × 10 31 yr at 90% C.L. when the signal was forced into a positive likelihood space (bounded). Values for the free oscillation time derived from various models are also provided in this article. Furthermore, this is the first search for neutron-antineutron oscillation with the deuteron as a target.« less
    Cited by 3
  6. Brightness and uniformity measurements of plastic scintillator tiles at the CERN H2 test beam

    Here, we study the light output, light collection efficiency and signal timing of a variety of organic scintillators that are being considered for the upgrade of the hadronic calorimeter of the CMS detector. The experimental data are collected at the H2 test-beam area at CERN, using a 150 GeV muon beam. In particular, we investigate the usage of over-doped and green-emitting plastic scintillators, two solutions that have not been extensively considered. We present a study of the energy distribution in plastic-scintillator tiles, the hit efficiency as a function of the hit position, and a study of the signal timing formore » blue and green scintillators.« less
  7. Radioactive source calibration test of the CMS Hadron Endcap Calorimeter test wedge with Phase I upgrade electronics

    The Phase I upgrade of the CMS Hadron Endcap Calorimeters consists of new photodetectors (Silicon Photomultipliers in place of Hybrid Photo-Diodes) and front-end electronics. The upgrade will eliminate the noise and the calibration drift of the Hybrid Photo-Diodes and enable the mitigation of the radiation damage of the scintillators and the wavelength shifting fibers with a larger spectral acceptance of the Silicon Photomultipliers. The upgrade also includes increased longitudinal segmentation of the calorimeter readout, which allows pile-up mitigation and recalibration due to depth-dependent radiation damage. As a realistic operational test, the responses of the Hadron Endcap Calorimeter wedges were calibrated with amore » $$^{60}$$Co radioactive source with upgrade electronics. The test successfully established the procedure for future source calibrations of the Hadron Endcap Calorimeters. Lastly we describe the instrumentation details and the operational experiences related to the sourcing test.« less

    The IceCube collaboration has reported the first detection of high-energy astrophysical neutrinos, including ∼50 high-energy starting events, but no individual sources have been identified. It is therefore important to develop the most sensitive and efficient possible algorithms to identify the point sources of these neutrinos. The most popular current method works by exploring a dense grid of possible directions to individual sources, and identifying the single direction with the maximum probability of having produced multiple detected neutrinos. This method has numerous strengths, but it is computationally intensive and because it focuses on the single best location for a point source,more » additional point sources are not included in the evidence. We propose a new maximum likelihood method that uses the angular separations between all pairs of neutrinos in the data. Unlike existing autocorrelation methods for this type of analysis, which also use angular separations between neutrino pairs, our method incorporates information about the point-spread function and can identify individual point sources. We find that if the angular resolution is a few degrees or better, then this approach reduces both false positive and false negative errors compared to the current method, and is also more computationally efficient up to, potentially, hundreds of thousands of detected neutrinos.« less
  9. Gravitational Waves from F-modes Excited by the Inspiral of Highly Eccentric Neutron Star Binaries

    As gravitational wave instrumentation becomes more sensitive, it is interesting to speculate about subtle effects that could be analyzed using upcoming generations of detectors. One such effect that has great potential for revealing the properties of very dense matter is fluid oscillations of neutron stars. These have been found in numerical simulations of the hypermassive remnants of double neutron star mergers and of highly eccentric neutron star orbits. Here we focus on the latter and sketch out some ideas for the production, gravitational-wave detection, and analysis of neutron star oscillations. These events will be rare (perhaps up to several tensmore » per year could be detected using third-generation detectors such as the Einstein Telescope or the Cosmic Explorer), but they would have unique diagnostic power for the analysis of cold, catalyzed, dense matter. Furthermore, these systems are unusual in that analysis of the tidally excited f-modes of the stars could yield simultaneous measurements of their masses, moments of inertia, and tidal Love numbers, using the frequency, damping time, and amplitude of the modes. They would thus present a nearly unique opportunity to test the I-Love-Q relation observationally. The analysis of such events will require significant further work in nuclear physics and general relativistic nonlinear mode coupling, and thus we discuss further directions that will need to be pursued. For example, we note that for nearly grazing encounters, numerical simulations show that the energy delivered to the f-modes may be up to two orders of magnitude greater than predicted in the linear theory.« less
  10. Overview of Variable Renewable Energy Regulatory Issues: A Clean Energy Regulators Initiative Report

    This CERI report aims to provide an introductory overview of key regulatory issues associated with the deployment of renewable energy -- particularly variable renewable energy (VRE) sources such wind and solar power. The report draws upon the research and experiences from various international contexts, and identifies key ideas that have emerged from the growing body of VRE deployment experience and regulatory knowledge. The report assumes basic familiarity with regulatory concepts, and although it is not written for a technical audience, directs the reader to further reading when available. VRE deployment generates various regulatory issues: substantive, procedural, and public interest issues,more » and the report aims to provide an empirical and technical grounding for all three types of questions as appropriate.« less

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