Engineering Papers⌕ Search

SEARCH · Engineering Papers

Results for “Precise”

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.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 109 records · Page 6
All sourcesNASA NTRSDOE OSTI
DOE OSTI2015

Non-degenerate two photon absorption enhancement for laser dyes by precise lock-in detection

This study demonstrates a measurement system for a non-degenerate two-photon absorption (NDTPA) spectrum. The NDTPA light sources are a white light super continuum beam (WLSC, 500 ∼ 720 nm) and a fundamental beam (798 nm) from a Ti:Sapphire laser. A reliable broadband NDTPA spectrum is acquired in a single-shot detection procedure using a 128-channel lock-in amplifier. The NDTPA spectra for several common laser dyes are measured. Two photon absorption cross section enhancements are found in the experiment and validated by theoretical calculation for all of the chromophores.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2016

X-ray diffraction gratings: Precise control of ultra-low blaze angle via anisotropic wet etching

Diffraction gratings are used from micron to nanometer wavelengths as dispersing elements in optical instruments. At shorter wavelengths, crystals can be used as diffracting elements, but due to the 3D nature of the interaction with light are wavelength selective rather than wavelength dispersing. There is an urgent need to extend grating technology into the x-ray domain of wavelengths from 1 to 0.1 nm, but this requires the use of gratings that have a faceted surface in which the facet angles are very small, typically less than 1°. Small facet angles are also required in the extreme ultra-violet and soft x-ray energy ranges in free electron laser applications, in order to reduce power density below a critical damage threshold. In this work, we demonstrate a technique based on anisotropic etching of silicon designed to produce very small angle facets with a high degree of perfection.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2012

A PRECISION PHOTOMETRIC COMPARISON BETWEEN SDSS-II AND CSP TYPE Ia SUPERNOVA DATA

Consistency between Carnegie Supernova Project (CSP) and SDSS-II Supernova Survey ugri measurements has been evaluated by comparing Sloan Digital Sky Survey (SDSS) and CSP photometry for nine spectroscopically confirmed Type Ia supernova observed contemporaneously by both programs. The CSP data were transformed into the SDSS photometric system. Sources of systematic uncertainty have been identified, quantified, and shown to be at or below the 0.023 mag level in all bands. When all photometry for a given band is combined, we find average magnitude differences of equal to or less than 0.011 mag in ugri, with rms scatter ranging from 0.043 to 0.077 mag. The u-band agreement is promising, with the caveat that only four of the nine supernovae are well observed in u and these four exhibit an 0.038 mag supernova-to-supernova scatter in this filter.

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2015

Precise absolute γ -ray and β - -decay branching intensities in the decay of Cu 29 67

In this work, absolute γ-ray emission probabilities in the β - decay of 67 Cu were measured by means of γ-ray and β - -decay singles and β - -γ coincidences. The new results, together with the known decay scheme of 67 Cu , were used to determine absolute β - -decay branching intensities. The present data differ significantly from previously published values. In addition, the half-life of the I π = 1/2 - isomer in 67 Zn was measured as T 1/2 = 9.37(4) μs, in a good agreement with earlier measurements. Lastly, from the analysis of the Fermi–Kurie plots, Q β - ( g.s.) = 560.3 (10) keV was deduced, which differs from the previously measured value of 577(8) keV but is in good agreement with Q β - ( g.s.) = 561.3 (15) keV recommended in the latest Atomic Mass Evaluation.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2018

Acoustic scaling of linear and mode-coupled anisotropic flow; implications for precision extraction of the specific shear viscosity

The n th -order linear flow coefficients v n L ( n = 2 , 3 , 4 , 5 ) , and the corresponding nonlinear mode-coupled ( mc ) coefficients v 4 , ( 2 , 2 ) mc , v 5 , ( 2 , 3 ) mc , v 6 , ( 3 , 3 ) mc , and v 6 , ( 2 , 2 , 2 ) mc , are studied for Pb+Pb collisions at s N N = 2.76 TeV. Both sets of coefficients suggest a common acoustic scaling pattern of exponential viscous modulation, with a rate proportional to the square of the harmonic numbers and the mean transverse momenta (respectively), and inversely proportional to the cube root of the charged particle multiplicity [ ( N ch ) 1 / 3 ] , which characterizes the dimensionless size of the systems produced in the collisions. These patterns and their associated scaling parameters offer new stringent constraints for eccentricity-independent estimates of the specific shear viscosity η s ( T ) and the viscous correction to the thermal distribution function for the matter produced in the collisions. They also give crucial constraints for extraction of the initial-state eccentricity spectrum.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2011

Precision Measurement of the Ratio B(t{yields}Wb)/B(t{yields}Wq) and Extraction of V{sub tb}

We present a measurement of the ratio of top quark branching fractions R=B(t{yields}Wb)/B(t{yields}Wq), where q can be a d, s, or b quark, in the lepton+jets and dilepton tt final states. The measurement uses data from 5.4 fb{sup -1} of pp collisions collected with the D0 detector at the Fermilab Tevatron Collider. We measure R=0.90{+-}0.04, and we extract the Cabibbo-Kobayashi-Maskawa (CKM) matrix element |V{sub tb}| as |V{sub tb}|=0.95{+-}0.02, assuming unitarity of the 3x3 CKM matrix.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗