Secondary electrons and photons in the upper atmosphere
Secondary electrons and photons energy spectra and depth dependence in upper atmosphere from numerical solution of one dimensional transport equations
Beuermann, K. P.↗
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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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Inelastic-electron-scattering cross-section measurements at 0.2-, 1.0-, and 2.0-MeV incident electron energies
Inelastic electron scattering cross sections and energy spectra from Al and Au targets, using magnetic analyzer with high resolution detector
Edmonson, N.↗
Photoelectrons and related ionospheric effects
Photoelectron flux and energy spectra effects on ionospheric phenomena, examining sunlit and predawn atmospheric models
Banks, P. M.↗
Experiment M409: Bremsstrahlung spectrometer
Spectrometric data were used to gain information for computation of the flux-energy spectra of bremsstrahlung inside the Gemini spacecraft and to determine if energetic electrons are able to penetrate the vehicle walls. The spectra were compared with computer predicted bremsstrahlung spectra by the use of data from beta spectrometers flown on Gemini 10 and 12 missions. The calculations of bremsstrahlung radiation involved uncertainties because of the small amount of information available on cross-section interaction and because of the complex, heterogeneous composition of the spacecraft. The bremsstrahlung detector was designed for time-differentiated measurement of the electron-induced gamma rays over a large section of the vehicle. Preliminary analysis of the data obtained during the missions was indicative that electrons did penetrate the spacecraft wall.
Lindsey, R. S., Jr.↗
Observations of the scatter-free solar-flare electrons in the energy range 20-1000 keV
Observations of the scatter-free electron events from solar active region McMath No. 8905 are presented. The measurements were made on Explorer 33 satellite. The data show that more than 80% of the electrons from these events undergo no or little scattering and that these electrons travel only approximately 1.5 a.u. between the sun and the earth. The duration of these events cannot be accounted fully by velocity dispersion alone. It is suggested that these electrons could be continuously injected into interplanetary medium for a time interval of approximately 2 to 3 minutes. Energy spectra of these electrons are discussed.
Wang, J. R.↗
The measurement of radiation exposure of astronauts by radiochemical techniques
Gamma analyses of the neutron-activated fecal samples from the Apollo 12 and 13 missions were completed, and the data are being evaluated. Samples of the exposed Apollo 12 solar wind composition foil and blank foils were obtained for analysis of the Po-2/0 (Pb-210, Rn-222) content. It is expected that the determination of the Po-210 content of these foils will yield the concentration of radon atoms incident on the foil while exposed to the lunar atmosphere, and this indirectly will permit an estimate of the average uranium concentration of the lunar surface. Proposals to measure the cosmic-ray intensity and energy spectra inside and outside of late Apollo and Project Skylab spacecraft by exposing and subsequently analyzing pure metal foils, and to measure the elemental mass balance in Project Skylab astronauts by instrumental neutron activation analysis of the intake and excreta are summarized.
Brodzinski, R. L.↗
Galactic cosmic ray heavy primary secondary doses
Results of a calculation which estimates the heavy primary secondary doses from cosmic ray interaction data are reported. The incident galactic cosmic ray heavy primary spectrum is represented as the sum of helium, nitrogen, magnesium, and iron components. The incident iron nuclei are allowed to fragment into lesser Z secondaries, which are assumed to travel in the same direction and start with the same energy per nucleon as the interacting primary. The total emergent particle energy spectra and dose are then presented for the galactic heavy primary spectrum incident on aluminum and tissue slabs. The importance of the fragmentation parameters assumed is also evaluated. The total dose from the heavy primaries and their secondaries is found to be reduced by only a factor of two in 20 g/sq cm of shielding.
Wilkinson, M. C.↗
Artificial perturbations of the radiation belts
A review is given of the properties of the radiation belts which have been produced by high-altitude nuclear detonations. The low-yield, Argus devices, 1, 2, and 3, and the Soviet test of 1 November 1962 injected intense electron fluxes in narrow L-shell intervals, with peaks at L = 1.72, 2.11, 2.17, and 1.77, respectively. The energy spectra of the electrons were indistinguishable from the equilibrium fission beta spectrum, and the fluxes initially decayed at rates approximately proportional to (time) sup -1.1. The high-yield devices, Starfish and the Soviet tests of 22 October and 28 October 1962, injected electrons over wide ranges. At L values near the lower boundary, the electron spectra appeared to be softer at the higher L values.
Cladis, J. B.↗
Apollo mission experience
Dosimetric implications for manned space flight are evaluated by analyzing the radiation field behind the heavy shielding of a manned space vehicle on a near-earth orbital mission and how it compares with actual exposure levels recorded on Apollo missions. Emphasis shifts from flux densities and energy spectra to incident radiation and absorbed doses and dose equivalents as they are recorded within the ship at locations close to crew members.
Schaefer, H. J.↗
Application of the matrix exponential kernel
A point matrix kernel for radiation transport, developed by the transmission matrix method, has been used to develop buildup factors and energy spectra through slab layers of different materials for a point isotropic source. Combinations of lead-water slabs were chosen for examples because of the extreme differences in shielding properties of these two materials.
Rohach, A. F.↗
Frequency of light-flashes induced by Cerenkov radiation from heavy cosmic-ray nuclei
The expected frequency was calculated for light flashes induced in the dark-adapted eye by Cerenkov radiation from the flux of heavy nuclei that exists in space beyond the geomagnetic field. The expected frequency of light flashes depends on the threshold number of photons that must be absorbed in a rod cluster. The results of the calculation are presented as a curve of the mean frequency of light flashes versus the threshold number of absorbed photons. The results are not sensitive to variations in the path length from 5 to 15 grams per square centimeter of water-equivalent before the nucleus reaches the retina. Calculations were based on the fluxes and energy spectra of galactic cosmic ray nuclei of helium to iron, measured at a time of minimum solar modulation. The expected light flash frequencies induced by Cerenkov radiation are consistent with the frequencies reported by the astronauts on Apollo missions 11 through 14.
Madey, R.↗
Direct stimulation of the retina by the method of virtual-quanta for heavy cosmic-ray nuclei
The contribution to the frequency of visual sensations induced in the dark-adapted eye by the virtual photon field was calculated, this field is associated with the heavy nuclei that exist in space beyond the geomagnetic field. In order to determine the probability that the virtual photon field induces a light flash, only the portion of the virtual photon spectrum that corresponds to the known frequency dependence of the sensitivity of human rods to visible light was utilized. The results can be expressed as a curve of the mean frequency of light flashes induced by the absorption of at least R virtual photons versus the threshold number R. The contribution to the light flash frequency from the virtual photon field of heavy cosmic ray nuclei is smaller than that from Cerenkov photons. The flux and energy spectra of galactic cosmic ray nuclei helium to iron were used.
Mcnulty, P. J.↗
Development of an X-ray surface analyzer for planetary exploration
An ultraminiature X-ray fluorescence spectrometer was developed which can obtain data on element composition not provided by present spacecraft instrumentation. The apparatus employs two radioisotope sources (Fe-55 and Cd-109) which irradiate adjacent areas on a soil sample. Fluorescent X-rays emitted by the sample are detected by four thin-window proportional counters. Using pulse-height discrimination, the energy spectra are determined. Virtually all elements above sodium in the periodic table are detected if present at sufficient levels. Minimum detection limits range from 30 ppm to several percent, depending upon the element and the matrix. For most elements, they are below 0.5 percent. Accuracies likewise depend upon the matrix, but are generally better than plus or minus 0.5 percent for all elements of atomic number greater than 14. Elements below sodium are also detected, but as a single group.
Clark, B. C.↗
An energetic charged particle experiment on the asteroid/Jupiter missions, Pioneers F andG
The experiment package, consisting of seven Geiger-Mueller tubes as basic sensors, is described, including the instrumental characteristics and tube arrangements. The capabilities of surveying the absolute intensities, energy spectra, angular distributions of energetic electrons and protons in the Jupiter magnetosphere are discussed.
Vanallen, J. A.↗
SM91: Observations of interchange between acceleration and thermalization processes in auroral electrons
Results from a Nike-Tomahawk sounding rocket flight launched from Fort Churchill are presented. The rocket was launched into a breakup aurora at magnetic local midnight on 21 March 1968. The rocket was instrumented to measure electrons with an electrostatic analyzer electron spectrometer which made 29 measurements in the energy interval 0.5 KeV to 30 KeV. Complete energy spectra were obtained at a rate of 10/sec. Pitch angle information is presented via 3 computed average per rocket spin. The dumped electron average corresponds to averages over electrons moving nearly parallel to the B vector. The mirroring electron average corresponds to averages over electrons moving nearly perpendicular to the B vector. The average was also computed over the entire downward hemisphere (the precipitated electron average). The observations were obtained in an altitude range of 10 km at 230 km altitude.
Pongratz, M.↗
Suprathermal ion detector results from Apollo missions.
This paper reviews briefly the knowledge of the ion environment of the moon as obtained from the Apollo Lunar Surface Experiments Package, Suprathermal Ion Detector Experiment. Topics to be discussed include: an interplanetary shock as seen from the lunar surface; bow shock and magnetosheath ions; magnetotail plasma seen during a magnetic disturbance; suprathermal ions seen during passage of the sunset and sunrise terminators; and ions associated with neutral gas clouds in the vicinity of the moon, and in particular the low energy mono-energetic spectrum of these ions. It is believed that these low energy spectra and some terminator ions can be explained by ion acceleration by the interplanetary electric field. This paper serves as catalog to references to these and other related phenomena.
Freeman, J. W., Jr.↗
Evidence of a diffuse magnetopause boundary.
Observational evidence is presented to show that the magnetosphere-magnetopause boundary was diffuse during the Pioneer 8 magnetopause traversal on Dec. 14 and 15, 1967. This boundary was characterized by proton fluxes of significantly lower intensity than those observed in the magnetosheath. In addition, the angles of flow associated with the fluxes at the boundary were more diverse than those observed in the magnetosheath. Proton energy spectra are presented to indicate the change in the spectral shape at the boundary. The observational evidence is consistent with calculations by Axford and Dryer of a viscous magnetopause boundary layer, which is a function of an anomalous nonclassical kinematic viscosity. The observational evidence presented for the diffuse magnetosphere boundary may also be consistent with Dungey's model reconnection of magnetic field lines and an open magnetosphere.
Intriligator, D. S.↗
Precision X-ray telescopes on HEAO-C.
Discussion of precision X-ray telescopes which are to be mounted on HEAO-C aircraft designed to study the structure, energy spectra and transient behavior of specific X-ray objects by the scanning and mapping of the sky. The design features and performance characteristics of the three high-resolution X-ray telescopes and their optical systems are considered. Mission equipment specifications and systems diagrams are appended. The HEAO-C mission is planned for launching by the Shuttle in the late 70s, with the capability of pointing to within one arc minute of X-ray sources for long periods of time.
Dailey, C. C.↗