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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 181 records · Page 10
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Signal of right-handed currents using B → K * ℓ + ℓ - observables at the kinematic endpoint

The decay mode B→K*ℓ + ℓ - is one of the most promising modes to probe physics beyond the standard model (SM), since the angular distribution of the decay products enable measurement of several constraining observables. LHCb has recently measured these observables using 3fb -1 of data as a binned function of q 2 , the dilepton invariant mass squared. We find that LHCb data implies evidence for right-handed currents, which are absent in the SM. These conclusions are derived in the maximum q 2 limit and are free from hadronic corrections. In conclusion, our approach differs from other approaches that probe new physics at low q 2 as it does not require estimates of hadronic parameters but relies instead on heavy quark symmetries that are reliable at the maximum q 2 kinematic endpoint.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Measurement of low energy ionization signals from Compton scattering in a charge-coupled device dark matter detector [Measurement of low energy ionization signals from Compton scattering in a CCD dark matter detector]

In this paper, an important source of background in direct searches for low-mass dark matter particles are the energy deposits by small-angle scattering of environmental γ rays. We report detailed measurements of low-energy spectra from Compton scattering of γ rays in the bulk silicon of a charge-coupled device (CCD). Electron recoils produced by γ rays from 57 Co and 241 Am radioactive sources are measured between 60 eV and 4 keV. The observed spectra agree qualitatively with theoretical predictions, and characteristic spectral features associated with the atomic structure of the silicon target are accurately measured for the first time. A theoretically motivated parametrization of the data that describes the Compton spectrum at low energies for any incident γ-ray flux is derived. The result is directly applicable to background estimations for low-mass dark matter direct-detection experiments based on silicon detectors, in particular for the DAMIC experiment down to its current energy threshold.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2019

Yield and Emplacement Depth Effects on Acoustic Signals from Buried Explosions in Hard Rock

Subterranean energy releases such as explosions and earthquakes may disturb the Earth-atmosphere interface, creating acoustic waves that can travel great distances. These waves provide a record of the ground motion directly above the event. The information they encode may provide critical insight into the depth and size of underground explosions, the sequence of events immediately before volcanic eruptions, and the magnitude of strong motion resulting from earthquakes. However, the effect of event size and burial depth on the resulting acoustic wave has not been explored in detail. The relationship between acoustic amplitude, frequency, and energy is investigated for a series of well-characterized underground chemical explosions in granite. Acoustic amplitude was found to vary linearly with explosive yield divided by emplacement depth. Peak acoustic frequency appears to be a function of explosive yield alone. The ratio of radiated acoustic energy to source energy had a relatively poor fit to yield, depth, and combinations thereof. These relationships suggest that acoustic analysis can be used to determine the size and depth of a buried explosion. The results presented here have particular relevance to the nuclear monitoring community, because depth is difficult to determine with seismic methods.

58 GEOSCIENCES↗