Cosmic X rays and gamma rays
Diffuse cosmic X and gamma ray spectrum analysis, considering implications for Compton scattering models in intergalactic space
Ipavich, F. M.↗
SEARCH · Engineering Papers
Results for “ray”
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.
Primordial radionuclide abundances, solar proton and cosmic-ray effects and ages of Apollo 11 lunar samples by non-destructive gamma ray spectrometry
Apollo 11 lunar rock and fines primordial radionuclide abundances and concentration gradients by gamma ray spectrometry at Lunar Receiving Laboratory
Bell, P. R.↗
Spallation limits on interstellar fluxes of low-energy cosmic rays and nuclear gamma rays
Spallation limits on low energy cosmic and nuclear gamma rays interstellar fluxes, evaluating fast particle effects on interstellar medium
Fowler, W. A.↗
Topics in solar cosmic ray and X-ray production
Characteristics of energetic interplanetary particles and X rays produced by solar activity
Cline, T. L.↗
The isotropy of the cosmic gamma ray flux between 1 and 6 MeV and its implications for future gamma ray investigations
Galactic and extragalactic origin of cosmic gamma ray flux between 1 and 6 MeV
Stecker, F. W.↗
Low-energy cosmic ray protons from nuclear interactions of cosmic rays with the interstellar medium.
The intensity of low-energy (less than 100 MeV) protons from nuclear interactions of higher-energy (above 100 MeV) cosmic rays with the interstellar medium is calculated. The resultant intensity in the 10- to 100-MeV range is larger by a factor of 3-5 than the observed proton intensity near earth. The calculated intensity from nuclear interactions constitutes a lower limit on the actual proton intensity in interstellar space.
Wang, H. T.↗
Development of a position sensitive X-ray detector for use in a light weight X-ray diffractometer
The characteristics of a curved position sensitive X-ray detector are discussed. Emphasis is placed on the analysis of operation in a focusing diffraction geometry. Problems encountered in constructing the sensor are described. Construction drawings of the sensor components are provided.
Semmler, R. A.↗
Interpretation of various radiation backgrounds observed in the gamma-ray spectrometer experiments carried on the Apollo missions and implications for diffuse gamma-ray measurements
Since the report of a preliminary analysis of cosmic gamma-ray measurements made during the Apollo 15 mission, an improved calculation of the spallation activation contribution has been made including the effects of short-lived spallation fragments, which can extend the correction to 15 MeV. In addition, a difference between Apollo 15 and 16 data enables an electron bremsstrahlung contribution to be calculated. A high level of activation observed in a crystal returned on Apollo 17 indicates a background contribution from secondary neutrons. These calculations and observations enable an improved extraction of spurious components and suggest important improvements for future detectors.
Dyer, C. S.↗
Relation of large-scale coronal X-ray structure and cosmic rays. II - Coronal control of interplanetary injection of 300 keV protons
We report the striking coronal control of low-energy solar particles from the solar flare of September 7, 1973. The flare was at S18, W46 (Carrington longitude 188 deg) in McMath Plage Region 12307. We find strong intensity gradients in heliolongitude (about 10% per deg) that are nearly identical in protons, helium, and medium nuclei at energies about 0.5 MeV/nuc, as well as relativistic electrons and 3 MeV protons. This pervasive gradient occurs at longitudes over bright X-ray emission structures east of the flare site which interconnect large-scale chromospheric polarity regions identifiable in H-alpha filtergrams.
Roelof, E. C.↗
Large-area multi-crystal NaI/Tl/ detectors for X-ray and gamma-ray astronomy
An array of large multicrystal NaI(Tl) detectors was constructed and used in a balloon-borne experiment to observe weak transient bursts of cosmic origin. The array had an active area of about 1 sq m and was sensitive to photons above 50 keV. Localized bursts which were observed are attributed to long-lived phosphorescence following large energy deposits by cosmic rays in the crystals.
Fishman, G. J.↗
Search for an X-ray identification of a strong gamma-ray source
X-rays from Cygnus X-3 were observed during early 1978 with the detectors of the SAS-3 satellite. These observations in conjunction with earlier UHURU and ANS data indicate that the 4.8 hr period of Cygnus X-3 is increasing at the rate of P/P = (5/1 plus or minus 1.3) x 10 to the minus 6 power/1 yr. The sign and magnitude for this change are incompatible with a rotation model for the period and are in reasonable agreement with model predictions for orbital changes associated with mass loss and transfer in a binary system.
Lamb, R. C.↗
Cosmic ray drift, shock wave acceleration and the anomalous component of cosmic rays
A model of the anomalous component of the quiet-time cosmic ray flux is presented in which ex-interstellar neutral particles are accelerated continuously in the polar regions of the solar-wind termination shock, and then drift into the equatorial regions of the inner heliosphere. The observed solar-cycle variations, radial gradient, and apparent latitude gradient of the anomalous component are a natural consequence of this model.
Pesses, M. E.↗
Further studies of the isotopic composition of cosmic ray Li, Be and B nuclei - Implications for the cosmic ray age
The isotopic compositions of Li, Be, and B nuclei were investigated by using balloon flight data and the dE/dx X(E) mode of analysis. 600 Be nuclei were considered, including 24 (Be-10) isotopes; the effect of solar modulation of the surviving fraction of (Be-10) measured in this experiment and limits on the age of cosmic rays are discussed. The isotopic composition of all Li, Be, and B nuclei is examined with respect to the fragmentation origin of these particles and the effects of solar modulation.
Webber, W. R.↗
Cosmic ray exposure ages of chondrites, pre-irradiation and constancy of cosmic ray flux in the past
Calibration of the production rate of the Ne-21 nuclide was accomplished by 4 methods based on (Al-26)-age, (Mn-53)-age, Kr-81/Kr-83, and Na-22/Ne-22. These production rates are normalized to a shielding parameter ratio Ne-22/Ne-21 = 1.11 and to the chemical composition of L chondrites; a value of P(21)(1.11) = 0.31 is suggested, and a production rate equation derived in terms of the 'F' parameters for L, LL, and H chondrites. The Al-26 half-life measurements are considered to evaluate the effects resulting from preirradiation of meteorites and to examine the data on the constancy of the cosmic ray flux in the light of current astronomical observations.
Nishizumi, K.↗
Cosmic ray drift, shock wave acceleration, and the anomalous component of cosmic rays
A model of the anomalous component of the quiet-time cosmic ray flux is presented in which ex-interstellar neutral particles are accelerated continuously in the polar regions of the solar-wind termination shock and then drift into the equatorial regions of the inner heliosphere. The observed solar-cycle variations, radial gradient, and apparent latitude gradient of the anomalous component are a natural consequence of this model.
Pesses, M. E.↗
A new method for focusing and imaging X-rays and gamma-rays with diffraction crystals
Bent diffraction crystals in which the intercrystalline-plane spacing is varied as a function of position in the crystal are used to focus monochromatic radiation from a point source or parallel beam down to a point image. Conversely, radiation from a point source can be focused into an outgoing parallel beam. The Bragg angle for diffraction of monochromatic radiation will now vary as a function of position in the crystal and this new degree of freedom is used to obtain focusing and imaging of the diffracted beam. This approach to focusing and imaging is applied to the design of a large-area, high resolution X-ray telescope that is also a high resolution monochromator with the unique feature that the width of the energy increment that is diffracted can be controlled and varied during the operation of the instrument. The field can be scanned with a wide energy increment and then switched to a narrow energy increment for the high resolution work. Both transmission and reflection type diffraction crystals can be used.
Smither, R. K.↗
Extended range X-ray telescope: X-ray microscope design
A glancing incidence X-ray microscope using a confocal hyperboloid ellipsoid mirror was designed to couple optically a Wolter 1 telescope to a CCD focal plane detector. Both the RMS spot size and the point spread function calculations were used to evaluate the resolution, defocusing, and vignetting effects of the system for microscope focal lengths of 1, 1.5, and 2 meters and for magnifications varying from 2 to 10x. For the specific application with the S-056 telescope, a 2 meter, 8x microscope with a fabrication ratio of the microscope mirror length to the inner diameter at hyperboloid ellipsoid intersection of 2.5 was designed to be used with a thinned, back illuminated CCD detector array with 320 by 512, 30 micron pixels.
Shealy, D. L.↗
A medium sensitivity X-ray survey using the Einstein Observatory - The log N-log S relation for extragalactic X-ray sources
The paper presents results of an X-ray survey of about 50 sq deg of the high galactic latitude sky at sensitivities in the range of 7 x 10 to the -14 to 5 x 10 to the -12 ergs/sq cm/s. The number-flux relation is derived for the extragalactic population to yield a best-fit power-law slope of 1.53 + or - 0.16, and the content of the sample is analyzed in terms of types of sources, appearing to be significantly different from the content of similar samples selected at higher fluxes. The medium sensitivity sample of extragalactic sources is dominated by active galactic nuclei, while samples selected at higher fluxes and higher energies are dominated by clusters of galaxies. Thus, the number-flux relation for extragalactic sources may be interpreted to a first approximation as the sum of the two different distributions with flatter and steeper slopes describing clusters and AGNs, respectively.
Maccacaro, T.↗