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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 307 records · Page 17
All sourcesNASA NTRSDOE OSTI
DOE OSTI2020

Time Resolution Measurements of EJ-232Q With Single- and Dual-Sided Readouts

In view of its importance to applications in high energy physics, nuclear security, and time-of-flight PET, the time resolution of 0.5% benzophenone-quenched EJ-232Q plastic scintillators of various lengths was studied using a fast waveform digitizer and fast PMTs. The scintillator sizes were 5 mm × 5 mm × 10, 25, 50, 75, or 100 mm. First, the timing measurements were performed by using a single PMT reading out one end. The degradation in time resolution with increasing scintillator length was studied. The irradiation geometry was also observed to have a non-negligible impact on the time resolution due to the variation of depth-of-interaction positions, especially for the scintillators with a high aspect ratio. Second, two PMTs were employed for a dual-sided readout. This readout together with the mean time method was demonstrated to be an effective approach to improve the timing performance since the depth-of-interaction-related effect was considerably mitigated. A time resolution of 79 ± 1 ps (full-width at half-maximum) has been achieved for the 5 × 5 × 10 mm 3 scintillator. The 5 × 5 × 100 mm 3 scintillator can still provide a time resolution as good as 172 ± 1 ps. Here, the energy range used for each was between 340 keVee and 450 keVee. In addition, the time information from individual PMTs in a dual-sided readout was able to show a time resolution almost identical to that determined with the mean-time-based technique after correcting for the depth-of-interaction variation for the 100 mm long scintillator.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Search for invisible decays of Higgs bosons in the vector boson fusion and associated ZH production modes

A search for invisible decays of Higgs bosons is performed using the vector boson fusion and associated ZH production modes. In the ZH mode, the Z boson is required to decay to a pair of charged leptons or a b b-bar quark pair. The searches use the 8 TeV pp collision dataset collected by the CMS detector at the LHC, corresponding to an integrated luminosity of up to 19.7 inverse femtobarns. Certain channels include data from 7 TeV collisions corresponding to an integrated luminosity of 4.9 inverse femtobarns. The searches are sensitive to non-standard-model invisible decays of the recently observed Higgs boson, as well as additional Higgs bosons with similar production modes and large invisible branching fractions. In all channels, the observed data are consistent with the expected standard model backgrounds. Limits are set on the production cross section times invisible branching fraction, as a function of the Higgs boson mass, for the vector boson fusion and ZH production modes. By combining all channels, and assuming standard model Higgs boson cross sections and acceptances, the observed (expected) upper limit on the invisible branching fraction at m[H] = 125 GeV is found to be 0.58 (0.44) at 95% confidence level. We interpret this limit in terms of a Higgs-portal model of dark matter interactions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Exploiting the flexibility and the polarization of ferroelectric perovskite surfaces to achieve efficient photochemistry and enantiospecificity

This research project explored the catalytic properties of complex surfaces of functional materials. The PI used first-principles density functional theory (DFT) calculations to explore a tightly integrated set of properties. The physical properties of complex functional materials that influence surface chemistry were explored, including bulk and surface electric dipoles, and surface conductivity. The energetic, compositional, electronic, and chemical properties of the surfaces of these materials were explored in detail, and connections between material properties and chemical reactivity were established. This project led to 28 publications, including Nat. Comm., JACS, 3 PRL, 7 PRB, 2 ACS Nano, 2 Nano Lett., 4 JPCL, 2 JCP, Chem. Mater., ACS Appl. Mater. Interfaces, Phys. Rev. Appl., and a U.S. Patent on surface catalysts. The key accomplishments in this project involved work in six coordinated areas: pioneering ways to control bulk dipoles in order to dynamically affect catalysis, exploring novel ways of bringing charge to the surface for redox catalysis, nonstoichiometric surfaces offering new sites for heterogeneous catalysis, illustrating how surface catalysis responds to applied pressure, catalytic growth of carbon-based materials, and new computational methods allowing more accurate exploration of molecule-surface interactions

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2024

Region of Interest Filter in DUNE DAQ

The Deep Underground Neutrino Experiment (DUNE) is the next generation neutrino experiment currently under construction. It consists of a broadband neutrino beam at Fermilab, a high precision near detector, and the largest liquid argon time projection chamber far detector ever designed at the Sanford Underground Research Facility (SURF). The Region of Interest (ROI) filter is designed for DUNE’s online Data Acquisition (DAQ) system to address data rate constraints and enable low energy physics in the <10 MeV range. The filter employs zero suppression on the detector signal, and by tuning the readout window and threshold the data rates can be reduced by >90%. Performance of the ROI is analyzed in LArsoft on MARLEY generated low energy MC events propagated through the detector simulation. Notably, the optimized ROI filter enables a lower trigger threshold for readout at ~5-10 MeV, allowing DUNE to explore low-energy physics, specifically focusing on solar boron 8 neutrinos which are relevant in this energy range. This advancement enhances DUNE's scientific capabilities, opening avenues for detailed analyses of previously inaccessible low-energy neutrino interactions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Performance and physics measurements at protoDUNE-SP

The protoDUNE Single Phase (protoDUNE-SP) TPC is a prototype for the DUNE far detector and it is currently under construction at CERN. It will not only serve as a test-bed for the engineering design and construction techniques but will also provide a set of key measurements for the future DUNE far detector.The new extension of the H4 beam-line at CERN will provide electron, muon and hadron beams with energies in the range of sub-GeV to a few GeV. The data collected during the test beams will be analysed to assess the performance of a state-of-the-art LAr TPC. For such detectors the event reconstruction is challenging and test beam data will allow the performance of the different reconstruction algorithms, which also involve machine-learning techniques, to be benchmarked and improved. Furthermore, important physics measurements are foreseen with protoDUNE-SP. For example, the study of pion interactions in argon using test beams is fundamental to understand some of the processes that will be seen as part of the primary neutrino interactions and which would modify the event signature in the DUNE detectors. ProtoDUNE-SP will provide new measurements of the pion-Ar cross-section, for both positive and negative charges, which will make a vital contribution to improve the current, very limited knowledge of such interactions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
NASA NTRS1982

Search for interstellar superheavy hydrogen

Models for fundamental physical interactions allow for the existence of stable or nearly stable elementary particles much heavier than the proton. Stellar spectra were searched for a positively charged superheavy particle, X(+), which, with a bound electron, should appear as apparently superheavy neutral hydrogen in the interstellar medium. An upper limit for the abundance of X relative to normal hydrogen in the line of sight toward the bright star gamma Cassiopeiae is 2 x 10 to the -8th.

Jura, M.↗
DOE OSTI2013

Nonperturbative short-range dynamics in TMDs

This presentation covers: deep inelastic processes and transverse momentum distributions; chiral symmetry breaking, including the physical picture, the dynamical model, and parton distributions; partonic structures, including transverse momentum distributions, coordinate space correlator, and short range correlations; and measurements of semi-inclusive deep inelastic scattering, correlations, and multi-parton processes in pp interactions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2014

Quasi-Elastic Scattering and Pion Production at MINER$\nu$A

MINER$\nu$A is a neutrino scattering experiment to make precision measurements of cross sections and investigate nuclear effects. A precise understanding of quasi-elastic and charged pion interactions is crucial to neutrino oscillation measurements. We present measurements of the differential cross sections for charged-current quasi-elastic scattering of neutrinos, antineutrinos and charged-current inclusive pion production on a hydrocarbon target. Comparisons of measurements with theoretical models are reported. We find the shape of the quasi-elastic differential cross section for neutrinos and antineutrinos disfavor a simple Relativistic Fermi Gas model and for charged-current pion differential cross section the data is consistent with the GENIE simulation using final state interactions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

MeV Scale Physics in MicroBooNE

MicroBooNE is a surface Liquid Argon Time Projection Chamber (LArTPC) neutrino experiment along the Booster Neutrino Beam (BNB) at Fermilab.Low electronics noise levels and millimeter spatial resolution allow this detector to be sensitive to MeV scale interactions. The surface location of the detector makes it challenging to distinguish interesting low energy activity such as nuclear de-excitation photons and neutron scatter resulting from neutrino interactions from the high rate of cosmic ray backgrounds.This poster presents a novel reconstruction for these MeV scale energy signatures in MicroBooNE, a measurement of the cosmic ray background and an effective rejection strategy.Finally we present preliminary results for measurements of MeV energy signatures produced in BNB neutrino interactions.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗