Neutron yield from the alpha, n reaction in the isotope oxygen-18
Neutron emission yield during Pu 238 alpha particles interactions with O 18, taking into account recoil Ne isotopes
Taherzadeh, M.↗
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Nuclear electromagnetic cascades from nuclei with Z larger than or equal to 3
A Monte Carlo simulation method was developed for studying nuclear-electromagnetic cascades initiated by high energy nuclei with Z or = 3 incident on heavy absorbers. The calculations are based on a cascade model which was first adjusted until it agreed with measurements made with protons at an accelerator. Modifications of the model used for protons include the incorporation of the probabilities for fragmentation of heavy nuclei into lighter nuclei, alpha particles, and nucleons. Mean values and fluctuations of the equivalent numbers of particles in the cascades at various depths in an iron absorber are presented for protons, carbon, and iron nuclei over the 30 to 300 GeV/nucleon energy range.
Jones, W. V.↗
Electrostatic, short-wavelength, turbulence as the source of ion heating in the solar wind
A mechanism is proposed for the nonthermal ion heating observed in the solar wind at 1 A.U. based on an electrostatic, short wavelength, instability between the ions in the observed colliding plasma streams. The modes lying on a plane perpendicular to the magnetic field thermalize most of the differential energy. The model suggests local electrostatic turbulence, that alpha-particles are heated more than protons, a maximum proton temperature T sub P 1 million k, and for the bulk speed U possibly a sq root of T sub P = aU + b relationship. These predictions are consistent with observations.
Papadoupoulis, K.↗
Solar wind rare gas analysis: Trapped solar wind helium and neon in Surveyor 3 material
The He-4 and Ne-20 contents in sections of the Surveyor 3 support strut samples were determined by optical and scanning electron microscopy and are compared to the results of the Apollo solar wind composition (SWC) experiments. The He-4/Ne-20 ratio in the samples from the sunlit side of the strut was approximately 300; the ratios determined in Apollo 12 lunar fines and SWC foil were below 100. The He-4/He-3 ratios were also determined, and the ratio obtained from Surveyor 3 material is higher than those found with Apollo 11 and 12 SWC experiments. The effects of spallation by cosmic rays or solar protons, stripping by cosmic ray or energetic solar alpha particles, recycling of solar wind He and radiogenic Ne, He from terrestrial atmosphere, mass discrimination near the moon, mass dependence of trapping probability, diffusion, and contamination by lunar dust are considered.
Buehler, F.↗
Energetic radiations from solar flares
An experiment designed to measure energetic X-rays, electrons, protons and alpha particles from solar flares aboard OGO 5 is reported. A brief statement of the objectives of the experiment is followed by a description of the instrumentation including detector characteristics and associated electronics. The data handling system is then described and the operational history of the experiment is discussed. This is followed by a description of the format of the magnetic data tapes and a summary of the major computer processing programs. The measurements made with this experiment within the first year of its operation have led to several basic results regarding the role of non-thermal electrons in the physics of solar flares. These results are described in the papers listed in the bibliography given at the end of this report.
Anderson, K. A.↗
The Apollo 15 X-ray fluorescence experiment
The objectives of Apollo 15 X-ray fluorescence experiment were to obtain a partial chemical map of a large portion of the moon. Gamma ray and alpha particle experiments were also performed. Mapping information from approximately 150 deg east on the moon to about 50 deg west was secured. Secondary X-rays characteristic of silicon, aluminum, and magnesium were measured.
Adler, I.↗
Apollo 15 orbital science summary.
In this paper, summary results of the Apollo 15 orbital science payload are given, and some quick-look results of Apollo 16 are discussed. Geochemical instruments, consisting of gamma-ray, X-ray, and alpha particle spectrometers, have provided a chemical map of the lunar surface flown over by Apollo 15. The Laser Altimeter and frontside gravity data have shown some unexpected results with regard to the lunar shape, and provided new basis for understanding lunar mascons. A magnetometer, aboard the small subsatellite, has located magnetic anomalies principally on the lunar farside, and has shown that the small lunar magnetic field is smoother on the frontside than on the back. The mass spectrometer, in orbit aboard the Command and Service Modules, has measured unexpectedly large populations of molecules at orbital altitude (110 km), mostly due to spacecraft contamination. Two major camera systems have provided the first systematic metric quality photography and concurrent high resolution stereo coverage of the lunar surface.
Esenwein, G. F.↗
Monte Carlo Simulation of Nonlinear Radiation Induced Plasmas
A Monte Carlo simulation model for radiation induced plasmas with nonlinear properties due to recombination was, employing a piecewise linearized predict-correct iterative technique. Several important variance reduction techniques were developed and incorporated into the model, including an antithetic variates technique. This approach is especially efficient for plasma systems with inhomogeneous media, multidimensions, and irregular boundaries. The Monte Carlo code developed has been applied to the determination of the electron energy distribution function and related parameters for a noble gas plasma created by alpha-particle irradiation. The characteristics of the radiation induced plasma involved are given.
Wang, B. S.↗
Lunar composition from Apollo orbital measurements
Several spectrometers carried in the Service Module of the Apollo 15 and Apollo 16 spacecraft were employed for the compositional mapping of the lunar surface. The observations involved the measurements of secondary (fluorescent) X-rays, gamma rays and alpha particle emissions. A large scale compositional map of over 20 percent of the lunar surface was obtained for the first time. It was possible to demonstrate interesting chemical differences between the mare and the highlands, to find specific areas of high radioactivity and to learn something about the composition of the moon's hidden side. Further the same devices were used to obtain useful astronomical data during the return to earth.
Adler, I.↗
A target design for irradiation of NaI at high beam current
A solution to the targetry problems encountered when the iodine nucleus is a target for cyclotron irradiation is given as a target design. A target based on this design was used in 30 microampere irradiations of 46 MeV alpha particles for one-half hour without significant damage. Such an irradiation produces 6 to 7 mCi of Cs-129. This target should also be considered for cyclotron production of the radioisotopes Cs-127, I-123, and Xe-127.
Blue, J. W.↗
Low energy cosmic ray protons from nuclear interactions of cosmic rays with the interstellar medium
The flux of secondary protons below 100 MeV in interstellar space is calculated using detailed cross sections and kinematics for proton-proton, and proton-alpha particle interactions.
Wang, H. T.↗
Calculations of neutron flux spectra induced in the earth's atmosphere by galactic cosmic rays
Calculations have been carried out to determine the neutron flux induced in the earth's atmosphere by galactic protons and alpha particles at solar minimum for a geomagnetic latitude of 42 N. Neutron flux spectra were calculated using Monte Carlo and discrete ordinates methods, and various comparisons with experimental data are presented. The magnitude and shape of the calculated neutron-leakage spectrum at the particular latitude considered support the theory that the cosmic-ray-albedo-neutron-decay mechanism is the source of the protons and electrons trapped in the Van Allen belts.
Armstrong, T. W.↗
Modulation of low-energy galactic cosmic rays over the present solar cycle
Explorer satellite observations of modulations in the cosmic ray spectrum during the entire period of the solar cycle show intensity variations in the proton and alpha modulated spectra. A positive correlation between plasma density and variation in cosmic ray intensity is found that breaks during the transition period when higher energy intensity is decreasing as the solar activity increases. It is suggested that the alpha particles lead the proton particles during transition periods and thus make the lag time shorter for high rigidity near the solar maximum and the solar minimum.
Vanhollebeke, M. A.↗
A target design for irradiation of NaI at high beam current.
A solution to the targetry problems encountered when the iodine nucleus is a target for cyclotron irradiation is given as a new target design. A target based on this design has been used in 30 microampere irradiations of 46 MeV alpha particles for one-half hour without significant damage. Such an irradiation produces 6 to 7 mCi of Cs-129, an isotope useful in nuclear medicine. This target should also be considered for cyclotron production of the radioisotopes Cs-127, I-123, and Xe-127.
Blue, J. W.↗
Lunar composition from Apollo orbital measurements.
Several spectrometers carried in the Service Module of the Apollo 15 and Apollo 16 spacecraft were employed for the compositional mapping of the lunar surface. The observations involved the measurements of secondary (fluorescent) X-rays, gamma-rays and alpha particle emissions. A large scale compositional map of over 20 percent of the lunar surface was obtained for the first time. It was possible to demonstrate interesting chemical differences between the mare and the highlands, to find specific areas of high radioactivity and to learn something about the composition of the moon's hidden side.
Adler, I.↗
Calculations of neutron flux spectra induced in the earth's atmosphere by galactic cosmic rays.
Calculations have been carried out to determine the neutron flux induced in the earth's atmosphere by galactic protons and alpha particles at solar minimum for a geomagnetic latitude of 42 N. Neutron flux spectra in the energy range from about 10 to the minus 8th to about 100,000 MeV at various depths in the atmosphere were calculated by using Monte Carlo and discrete ordinates methods, and various comparisons with experimental data are presented. The magnitude and shape of the calculated neutron leakage spectrum at the particular latitude considered support the theory that the cosmic ray albedo neutron decay (Crand) mechanism is the source of the protons trapped in the inner radiation belt.
Armstrong, T. W.↗
Apollo 15 and 16 results of the integrated geochemical experiment.
A number of experiments carried in orbit on the Apollo 15 and 16 spacecraft were used in the compositional mapping of the lunar surface. The observations involved measurements of secondary (fluorescent) X-rays, gamma rays and alpha particle emissions. A large scale compositional map of over 20% of the lunar surface was obtained for the first time. It was possible to demonstrate significant chemical differences between the mare and the highlands, to find specific areas of high radioactivity and to learn something about the composition of the moon's hidden side.
Adler, I.↗
Compact source of soft X-rays
Sources of soft X-rays uses alpha particles to fluoresce light elements such as boron, carbon, and magnesium. X-ray wavelengths are varied by changing target. Technique supplies broad range of monoenergetic X-rays whose energy can be adjusted very easily.
Gorenstein, P.↗