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in subjects: "X Radiation"

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Clonal theory of radiation carcinogenesis

In some cases, usually involving high-LET radiations, the dose response at low doses follows a power function of dose with exponent less than one over a wide dose range. This type of response is of great interest since (a) it implies greater effect per unit dose at progressively smaller doses, and (b) it is not predicted by most models and theories of radiobiology. A theoretical framework is presented for responses having the above characteristics over a dose range extending over a factor of 10… more

Date: January 1, 1982

Creator: Baum, J.W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Radiation induced micrencephaly in guinea pigs

A brain weight deficit of about 70 mg was induced at doses of approximately 75-mGy and a deficit of 60 mg was induced at 100 mGy. This confirms the effects projected and observed by Wanner and Edwards. Although the data do not demonstrate a clear dose-response relationship between the 75-mGy and 100-mGy groups, the data are statistically consistent with a dose-response effect because of the overlapping confidence intervals. The lack of a statistically significant observation is most likely rela… more

Date: January 1, 1991

Creator: Wagner, L.K.; Johnston, D.A. & Felleman, D.J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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X-ray, soft x-ray, and vuv beam position monitor

An x-ray beam position monitor has been developed and is currently operational at the NIST beamline X-24A of the National Synchrotron Light Source, Upton, NY. It was developed to accurately measure the vertical position of the synchrotron beam and to allow precise positioning of beamline optics. It is an area type monitor positioned 5.6 meters from the Tangent Point and precedes all beamline instrumentation. Vertical beam position is given by the differential photoemission current from two grid… more

Date: January 1, 1991

Creator: Karlin, B.A. (Brookhaven National Lab., Upton, NY (United States)); Cowan, P.L. (Argonne National Lab., IL (United States)) & Woicik, J.C. (National Inst. of Standards and Technology (IMSE), Gaithersburg, MD (United States))

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Some effects on the kinetics of muon-catalyzed fusion

Two important stages in the kinetics of muon-catalyzed d-t fusion are discussed: (1) atomic thermalization and hyperfine-state relaxation preceding molecular formation and (2) muon stripping and x-ray production if sticking occurs after nuclear fusion. Thermalization is accurately treated by Monte Carlo simulation. It is shown that thermalization and triplet quenching of the ..cap alpha mu.. atom may not finish before dt..mu.. formation in low-tritium targets, but that epithermal transients are… more

Date: January 1, 1986

Creator: Cohen, J.S.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Detectors for radiation dosimetry

For our purposes in this review, we note the following points: (1) for charged particle detection, these counters can be filled with any noble gas-quenching gas mixture that produces satisfactory electrical signals; (2) neutron counters, in which the neutrons are detected by their interaction with the specific filling of the chamber to yield an ionizing particle, require special gas mixtures containing /sup 3/He or BF/sub 3/, an alternative approach is to coat the inner surface of the cathode w… more

Date: September 1, 1979

Creator: Perez-Mendez, V.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Health physics aspects of nuclear radiations from deuterium beam injectors

Estimations are made for X-ray generation from the accelerator column of various neutral beam injectors. For the case of deuterium beam operation where 2.5-MeV D-D neutrons pose a serious health physics concern, neutron and tritium production rates from beam targets are calculated for different beam energies. Biological doses from these radiations and shielding requirements are discussed.

Date: February 1, 1978

Creator: Kim, J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Detection sensitivity of x-ray CT imaging for NDE of green-state ceramics

Improved ceramic-processing methods that use pressure slip-casting and injection molding are being developed at Norton Advanced Ceramics, with a goal of producing reliable structural ceramics for advanced heat engines. Nondestructive evaluation (NDE) of ceramic parts at different stages of processing can provide useful diagnostic information to help improve processing techniques. For example, an evaluation of density gradients in as-cast green-body samples can be used to judge mold performance … more

Date: 1991~

Creator: Gopalsami, N.; Rizo, P.; Ellingson, W. A. & Tracey, D. M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Design studies of a laser fusion power plant

The conceptual design of a laser fusion power plant has been undertaken to exploit recent developments in target design. Advanced high-gain targets which have been developed make it possible to significantly relax the laser and optical system requirements. The power plant design features a reactor concept which utilizes a thick falling region of liquid lithium to protect the first-wall from the neutrons, x-rays, and charged particles that are produced in the thermonuclear microexplosion. The li… more

Date: October 7, 1977

Creator: Maniscalco, J. A.; Meier, W. R. & Monsler, M. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Electron cyclotron resonance heating (ECRH) in the TMX-Upgrade tandem-mirror experiment

Results are described of engineering tests of operation of two gyrotrons from one power supply, tests of waveguide components and antennae, antenna design, and the x-ray shielding concept. Finally, we describe considerations of interaction with other system components.

Date: October 1, 1981

Creator: Griffin, D.H.; Rubert, R.R.; Simonen, T.C.; Stallard, B.W. & Wieskamp, T.F.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Energy balance measurements for Shiva

The Lawrence Livermore Laboratory Shiva laser-target interaction facility is designed for experiments at 20 to 30 terawatts. At this power level there will be larger fluxes of neutrons, x-rays, electrons and ions than have been previously measured. The measurements of energy converted into the various reaction products is crucial both in target design and performance analysis of the actual experiment. The total energy absorbed is measured by a box calorimeter surrounding the target except for b… more

Date: October 24, 1977

Creator: Glaros, S.S.; Rupert, V.C.; Gunn, S.R.; Phillion, D.W. & Kornblum, H.N.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Broadband diffractive lens

Significant progress has been made toward solving the century-old problem of chromatic aberrations in diffractive optics. Our approach exploits modern materials and microfabrication technology and is very different from the purely diffractive strategy,'' which is commonly employed and which results in multiple diffractive elements separated by a finite distance. We have developed a Fresnel zone plate lens comprised of a serial stack of patterned minus-filters which allows broadband radiation to… more

Date: May 28, 1991

Creator: Ceglio, N. M.; Hawryluk, A. M.; London, R. A.; Seppala, L. G. (Lawrence Livermore National Lab., CA (USA)) & Gaines, D. P. (Brigham Young Univ., Provo, UT (USA))

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Accelerator and Fusion Research Division: 1987 summary of activities

An overview of the design and the initial studies for the Advanced Light Source is given. The research efforts for the Center for X-Ray Optics include x-ray imaging, multilayer mirror technology, x-ray sources and detectors, spectroscopy and scattering, and synchrotron radiation projects. The Accelerator Operations highlights include the research by users in nuclear physics, biology and medicine. The upgrade of the Bevalac is also discussed. The High Energy Physics Technology review includes th… more

Date: April 1, 1988

Item Type: Report

Partner: UNT Libraries Government Documents Department

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X-ray spectra from the Cornell Electron-Beam Ion Source (CEBIS I)

Radiation emitted from the Cornell electron beam ion source (CEBIS I) has been surveyed with a Si(Li) x-ray detector. These spectra can be used to estimate backgrounds from electron bremsstrahlung and to evaluate the feasibility of atomic physics experiments using the CEBIS I source in this configuration. 1 ref., 2 figs.

Date: January 1, 1985

Creator: Johnson, B. M.; Jones, K. W.; Kostroun, V. O.; Ghanbari, E. & Janson, S. W.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Low-level x-irradiation of the brain during development morphological, physiological, and behavioral consequences. Final report, September 1, 1976--August 31, 1977

Morphological research was continued in the following areas: glial recovery patterns in the rat corpus callosum after x-irradiation during infancy; the prenatal development of the deep nuclei and cortex of the cerebellum; the prenatal development of the inferior olive, pontine gray and the precerebellar reticular nuclei; and the postnatal development of the olfactory bulb. In these studies autoradiography and x-irradiation were among the experimental techniques utilized. The behavioral studies,… more

Date: January 1, 1977

Creator: Altman, J.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

XTAL system of crystallographic programs: programmer's manual

This document establishes the basis for collaborative writing of transportable computer programs for x-ray crystallography. The concepts and general-purpose utility subroutines described here can be readily adapted to other scientific calculations. The complete system of crystallographic programs and subroutines is called XTAL and replaces the XRAY (6,7,8) system of programs. The coding language for the XTAL system is RATMAC (5). The XTAL system of programs contains routines for controlling exe… more

Date: February 1, 1980

Creator: Hall, S. R.; Stewart, J. M.; Norden, A. P.; Munn, R. J. & Freer, S. T.

Item Type: Report

Partner: UNT Libraries Government Documents Department

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Partially coherent x-rays from modern storage rings

Several routes to the development of ideal soft x-ray sources are now being actively pursued. These include atomic lasers, free electron lasers (FELs), and storage ring (synchrotron) undulators. For short wavelength (XUV) applications, FELs and undulators are very closely related, each being dependent on the development of well controlled (low ''emittance'') electron storage rings, with energies of order 0.5 to 1.5 GeV beam energy, and many period magnetic structures, referred to as undulators.… more

Date: November 1, 1984

Creator: Attwood, D.; Halbach, K. & Kim, K. J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Grazing incidence synchrotron radiation optics: correlation of performance with metrology

Image distortions produced by a cylinder mirror at the National Synchrotron Light Source are compared with performance predictions based on measurements of surface slope errors in the millimeter spatial period regime made with an optical surface profiler.

Date: June 1, 1986

Creator: Takacs, P. Z.; Hewitt, R. C. & Church, E. L.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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X-ray streak camera diagnostics of picosecond laser-plasma interactions

An x-ray streak camera is used to diagnose a laser-produced Al plasma with time resolution of {approximately}10 ps. A streak record of filtered emission and a time-integrated transmission grating spectrum reveal that the plasma radiation is dominated by emission from He- and H-like resonance lines. 11 refs.

Date: January 1, 1992

Creator: Cobble, J. A.; Fulton, R. D.; Jones, L. A.; Kyrala, G. A.; Schappert, G. T.; Taylor, A. J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Computed tomography using synchrotron radiation

X-ray computed tomography (CT) is a widely used method of obtaining cross-sectional views of objects. The high intensity, natural collimation, monochromaticity and energy tunability of synchrotron x-ray sources could potentially be used to provide CT images of improved quality. The advantages of these systems would be that images could be produced more rapidly with better spatial resolution and reduced beam artifacts. In addition, images, in some cases, could be acquired with elemental sensitiv… more

Date: September 1, 1983

Creator: Thompson, A. C.; Llacer, J.; Finman, L. C.; Hughes, E. B.; Otis, J. N.; Wilson, S. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Evaluation techniques for x-ray mirrors and systems using visible light

Severely diffraction-broadened visible light images from grazing incidence optical systems are measured and analyzed using a diffraction integral model to predict slope errors and image quality at XUV wavelengths.

Date: September 1, 1985

Creator: Takacs, P. Z. & Colbert, J.

Item Type: Article

Partner: UNT Libraries Government Documents Department

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Gene conversion in yeast as a function of linear energy transfer (LET) for low-LET radiation

The relative biological effectiveness (RBE) for low-LET radiation is known to depend on such factors as LET and dose rate. Microdosimetric calculations indicate that the biological target size could also be an important parameter, and calculations predict that the RBE for effects produced by hits in target sizes below about 100 nm should be unity for all low LET radiation. We have measured that RBE for gene conversion in yeast (a small target) for five different low LET photon sources, and the … more

Date: May 1, 1992

Creator: Unrau, P.; Morrison, D.P. (Pacific Northwest Lab., Richland, WA (United States)) & Johnson, J.R. (Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.)

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Rf breakdown studies in a SLAC disk-loaded structure

Rf breakdown studies in an S-band standing-wave disk-loaded accelerator structure have been completed. An equivalent traveling-wave accelerating gradient as high as 147 MV/m and a peak field in excess of 300 MV/m have been obtained. At these high gradients, considerable amounts of field emission and x-ray radiation are observed. Some of the field-emitted electrons are captured and focused by the rf fields and can be extracted on the axis of the structure. Their current, energy distribution and … more

Date: April 1, 1986

Creator: Wang, J.W.; Nguyen-Tuong, V. & Loew, G.A.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Advances in transmission x-ray optics

Recent developments in x-ray optics are reviewed. Specific advances in coded aperture imaging, zone plate lens fabrication, time and space resolved spectroscopy, and CCD x-ray detection are discussed.

Date: January 1, 1983

Creator: Ceglio, N.M.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Genetic effects of low x-ray doses. Progress report, October 1, 1976--September 30, 1977. [In Drosophila]

A linear-quadratic model of dose-kinetics is proposed for x-ray induced recessive lethal mutations in oogonia of Drosophila. From this it should follow that at higher total doses fractionation treatments should give a lower yield of mutations than an equivalent acute exposure. A dose of 6000 R, given acutely and in 3 different fractionation regimes gave results in the expected direction for 2 x 3000 R, and a significant decrease for 3 x 2000 R and for 4 x 1500 R fractionations.

Date: September 1, 1977

Creator: Abrahamson, S. & Meyer, H.U.

Item Type: Report

Partner: UNT Libraries Government Documents Department