40 Matching Results

Search Results

Advanced search parameters have been applied.
in subjects: "Photometry"  
Results: 1 - 24 next
open access

In-line multiwavelength photometer for the determination of heavy metal concentrations

Description: An in-line photometer has been developed for continuous monitoring of uranium and plutonium concentrations in high radiation environments of nuclear fuel reprocessing plants. The instrument is equipped with multiple narrow band interference filters to monitor sample transmission in the 400- to 800-nm range. The filters are mounted in a rotating filter wheel which is located in front of a stationary tungsten halide light source. The monochromatic light from the respective optical filters is tran… more
Date: January 1, 1981
Creator: Bostick, D. T.; Strain, J. E.; Dixon, D. M.; McCue, D. D. & Bauer, M. L.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

PG1159-035: a New, Hot, Non-DA Pulsating Degenerate

Description: The star was observed with a computer-controlled high-speed photometer. The light curve showed nearly sinusoidal variations with a period of about 8 minutes and a peak-to-peak amplitude of about 0.02 magnitude. Power spectra of the light curves were calculated. They showed peaks corresponding to periods of 460 and 539 seconds. The effective temperature of the star was found to exceed 5 x 10/sup 4/ K; lack of circular polarization indicated that the star does not have a large surface magnetic fi… more
Date: January 1, 1979
Creator: McGraw, J. T.; Starrfield, S. G.; Liebert, J. & Green, R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Commercialization of a thick film solar cell. Quarterly technical progress report, January 1, 1980-March 31, 1980

Description: Initial problems encountered in the screen printing of CdS films related to an undesirable surface texture on the film surface have been resolved by modification of ink rheology. Improvements have been made in CdS films through modification in firing conditions, ink composition, and fluxing. The CdS 13 micron thick films are devoid of through pores and have a resistivity of 1.65 ohm cm. A laser probe technique was developed to determine macro variations in solar cell films.
Date: January 1, 1980
Creator: McDonald, G.D.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Rarefaction velocities in shocked tantalum and the high-pressure melting point

Description: The optical analyzer technique has been used to determine the pressure at which shock compressed tantalum can no longer support a longitudinal elastic wave. At 295 GPa, the release wave velocity drops to a value consistent with a calculated bulk sound velocity, indicating partial melting. At higher shock pressures, the bulk sound velocity follows a constant rho ..gamma.. model, where ..gamma.. is the Grueneisen parameter. With these measurements we have identified melting on the Ta Hugonitot, a… more
Date: January 1, 1983
Creator: Brown, J. M. & Shaner, J. W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Supernova Models

Description: Recent progress in understanding the observed properties of Type I supernovae as a consequence of the thermonuclear detonation of white dwarf stars and the ensuing decay of the /sup 56/Ni produced therein is reviewed. Within the context of this model for Type I explosions and the 1978 model for Type II explosions, the expected nucleosynthesis and gamma-line spectra from both kinds of supernovae are presented. Finally, a qualitatively new approach to the problem of massive star death and Type II… more
Date: January 1, 1980
Creator: Woosley, S. E. & Weaver, T. A.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Precision Photometry to Study the Nature of Dark Energy

Description: Over the past decade scientists have collected convincing evidence that the expansion of the universe is accelerating, leading to the conclusion that the content of our universe is dominated by a mysterious 'dark energy'. The fact that present theory cannot account for the dark energy has made the determination of the nature of dark energy central to the field of high energy physics. It is expected that nothing short of a revolution in our understanding of the fundamental laws of physics is req… more
Date: January 30, 2011
Creator: Lorenzon, Wolfgang & Schubnell, Michael
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
open access

Measurement of special nuclear material concentrations in solution by absorption edge densitometry

Description: Absorption-edge densitometry is reviewed and examples of data obtained at the L/sub III/-edge of uranium are presented. Expressions are derived which allow the estimation of assay errors as a function of the transmission source intensity and the sample thickness for particular ranges of SNM concentration and matrix density. Specific examples are given and discussed.
Date: January 1, 1977
Creator: Tape, J. W.; Langner, D. G.; Parker, J. L. & Canada, T. R.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

Laser flow microphotometry for rapid analysis and sorting of mammalian cells. [X and gamma radiation]

Description: Quantitative precision measurements can be made of the optical properties of individual mammalian cells using flow microphotometry. Suspended cells pass through a special flow chamber where they are lined up for exposure to blue light from an argon-ion laser. As each cell crosses the laser beam, it produces one or more optical pulses of a duration equal to cell transit time across the beam. These pulses are detected, amplified, and analyzed using the techniques of gamma ray spectroscopy. Quanti… more
Date: January 1, 1976
Creator: Mullaney, P. F.; Steinkamp, J. A.; Crissman, H. A.; Cram, L. S.; Crowell, J. M.; Salzman, G. C. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

SDSS spectroscopic survey of stars

Description: In addition to optical photometry of unprecedented quality, the Sloan Digital Sky Survey (SDSS) is also producing a massive spectroscopic database. They discuss determination of stellar parameters, such as effective temperature, gravity and metallicity from SDSS spectra, describe correlations between kinematics and metallicity, and study their variation as a function of the position in the Galaxy. They show that stellar parameter estimates by Beers et al. show a good correlation with the positi… more
Date: January 1, 2007
Creator: Ivezic, Zeljko; Schlegel, D.; Uomoto, A.; Bond, N.; Beers, T.; Allende Prieto, C. et al.
Item Type: Refine your search to only Article
Partner: UNT Libraries Government Documents Department
open access

The Determination of Uranium in K-65 (Gangue Lead Cake)

Description: The major problems in this determination are the extraction of X from the sample and the isolation of the extracted X. The application of various analytical methods to these two problems indicates that the current method of analysis yields values which may be as much as 15% high. The current method of analysis is subject to positive and negative errors. The magnitude of these errors varies with techniques and with sample composition. The recommend method, although longer, is believed to be free… more
Date: January 1, 1948
Creator: Stevenson, J.W.
Item Type: Refine your search to only Report
Partner: UNT Libraries Government Documents Department
Back to Top of Screen