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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 163 records · Page 9
All sourcesNASA NTRSDOE OSTI
NASA NTRS2011

Compact Polarimetry Potentials

The goal of this study is to show the potential of a compact-pol SAR system for vegetation applications. Compact-pol concept has been suggested to minimize the system design while maximize the information and is declined as the ?/4, ?/2 and hybrid modes. In this paper, the applications such as biomass and vegetation height estimates are first presented, then, the equivalence between compact-pol data simulated from full-pol data and compact-pol data processed from raw data as such is shown. Finally, a calibration procedure using external targets is proposed.

vegetation height↗
NASA NTRS2014

Aerosol Polarimetry Sensor (APS): Design Summary, Performance and Potential Modifications

APS is a mature design that has already been built and has a TRL of 7. Algorithmic and retrieval capabilities continue to improve and make better and more sophisticated used of the data. Adjoint solutions, both in one dimensional and three dimensional are computationally efficient and should be the preferred implementation for the calculation of Jacobians (one dimensional), or cost-function gradients (three dimensional). Adjoint solutions necessarily provide resolution of internal fields and simplify incorporation of active measurements in retrievals, which will be necessary for a future ACE mission. Its best to test these capabilities when you know the answer: OSSEs that are well constrained observationally provide the best place to test future multi-instrument platform capabilities and ensure capabilities will meet scientific needs.

algorithms↗
DOE OSTI2023

${\Lambda}_c^{+}$ polarimetry using the dominant hadronic mode

The polarimeter vector field for multibody decays of a spin-half baryon is intro duced as a generalisation of the baryon asymmetry parameters. Using a recent amplitude analysis of the ${\Lambda}_c^{+}$ → $pK^-π^+$ decay performed at the LHCb experiment, we compute the distribution of the kinematic-dependent polarimeter vector for this process in the space of Mandelstam variables to express the polarised decay rate in a model-agnostic form. The obtained representation can facilitate polarisation measurements of the ${\Lambda}_c^{+}$ baryon and eases inclusion of the ${\Lambda}_c^{+}$ → $pK^-π^+$ decay mode in hadronic amplitude analyses.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2022

Precision Møller polarimetry for PREX-2 and CREX

The PREX-2 and CREX experiments in Hall A at Jefferson Lab are precision measurements of parity violating elastic electron scattering from complex nuclei. One requirement was that the incident electron beam polarization, typically , be known with 1% precision. We commissioned and operated a Møller polarimeter on the beam line that exceeds this requirement, achieving a precision of 0.89% for PREX-2, and 0.85% for CREX. The uncertainty is purely systematic, accumulated from several different sources, but dominated by our knowledge of the target polarization. Our analysis also demonstrates the need for accurate atomic wave functions in order to correct for the Levchuk Effect. We describe the details of the polarimeter operation and analysis, as well as (for CREX) a comparison to results from a different polarimeter based on Compton scattering.

43 PARTICLE ACCELERATORS↗