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A chart has been prepared that lists some of the properties relevant to cosmic ray studies of all the significant nuclides between lithium and nickel. On this chart there are shown all the possible decays that might be of interest in the unique conditions experienced by cosmic ray nuclei, various abundance figures and the probable nucleosynthesis processes of origin.
The continuity equation for cosmic ray propagation is used to derive a set of linear equations interrelating the fluxes of multiply charged nuclei as observed at any particular part of the galaxy. The derivation leads to model independent definitions for cosmic ray storage time, mean density of target nuclei and effective mass traversed. The set of equations form a common framework for comparisons of theories and observations. As an illustration, it is shown that there exists a large class of propagation models which give the same result as the exponential path length model. The formalism is shown to accommodate dynamic as well as equilibrium models of production and propagation.
Pitch angle diffusion of cosmic rays in hydromagnetic wave fields is considered strictly within the quasilinear approximation. It is shown that the popular assumption of an isotropic power spectrum tensor of magnetic fluctuations requires in this case equal forms and magnitudes of Alfven and magnetosonic wave spectra - a situation which is generally unlikely. The relative contributions to the pitch angle diffusion coefficient from the cyclotron resonances and Landau resonance due to the different types of waves are evaluated for a typical situation in the solar wind. Since in this approximation also the Landau resonance does not lead to particle reflections a proper consideration of the nonlinear particle orbits is indeed necessary to overcome the well known difficulties of quasilinear scattering theory for cosmic rays near 90 degrees pitch angle.
A formal model for the fluctuations of the cosmic-ray intensity near earth is presented. For frequencies exceeding 5 x 10 to the -6 Hz, the fluctuations are due to field-aligned-anisotropy induced interplanetary 'scintillations' of cosmic rays, while for lower frequencies the effects of non-field-aligned anisotropies dominate. Cross-correlations between neutron monitor counting rates and the interplanetary magnetic field components are presented which support the model.
Observations of solar cosmic rays between 0.1 MeV and 1 GeV are more consistent with scatter-free than diffusive propagation near 1 AU. Since these particles also are constrained to interplanetary magnetic field lines, the parallel and transverse flow are decoupled by collimated convection. Local propagation is therefore more appropriately described by Liouville's equation, and transport properties can be examined from the exact zeroeth and first moments of the equation averaged over all directions in momentum space. Observational results which may be explained directly without invoking local scattering include the decay of solar flare events as well as the radial gradient, diurnal and semidiurnal variation of galactic cosmic rays.
A nuclear emulsion detector known as the Apollo Light Flash Moving Emulsion Detector (ALFMED) was designed: (1) to record tracks of primary cosmic rays; (2) to provide time-of-passage information via a relative plate translation technique; (3) to provide particle trajectory information; and (4) to fit into a masklike device that could be located about the head and eyes of an astronaut. An ALFMED device was worn by an astronaut observing light flashes for 60 minutes on each of the last two Apollo missions. During the Apollo 17 experiment seventeen separate flashes were reported by the observer. With one-third of the total plate area completely analyzed, two definite correlations have been found between Z greater than 8 cosmic ray nuclei traversing an eye and the reports of visual sensations.
Recent observations with cosmic ray telescopes aboard the Pioneer 10 space probe have revealed an anomalous spectrum of nitrogen and oxygen nuclei relative to other nuclei such as carbon in the quiet time cosmic radiation below about 40 MeV/nuc. These observations are extended with additional data from Pioneer 10 and considerable new data from an identical telescope aboard Pioneer 11. In addition to the enhancement of nitrogen and oxygen nuclei observed earlier, the intensity of neon is enhanced as well. The spectra of boron, magnesium, and silicon appear to be similar to that of carbon. Data on the isotopic composition, solar modulation, and radial gradient of these nuclei are presented.
The cosmic ray telescopes on Pioneer 10 and 11 are used to examine solar cosmic ray events out to a distance about 5 AU from the sun. A detailed error analysis of the cosine fit to the anisotropy is presented. The anisotropy and intensity time characteristics during solar events are discussed as a function of radial distance.
The flux density of cosmic-ray positrons and electrons was measured by a balloon-borne spark chamber magnetic spectrometer in two flights in an attempt to study the solar modulation of galactic cosmic rays. The total electron flux was found to be about 0.03/cu m/s/sr/MeV between 70 and 800 MeV and to increase toward lower energies, while the positron flux decreased sharply toward lower energies from about 0.008/cu m/s/sr/MeV at 650 MeV and only upper limits were obtained for positrons below 200 MeV. At energies above 180 MeV, the spherically symmetrical Fokker-Planck equation with a diffusion coefficient proportional to the particle rigidity provided a reasonable fit to both positron and total electron data, while at energies below 180 MeV, the data were consistent with a continuation of the same diffusion coefficient and local source of electrons, or a change in the diffusion coefficient to a constant value.
A kinetic equation for interplanetary cosmic rays is set up with the aid of weak-plasma-turbulence theory for an idealized radially symmetric model of the interplanetary magnetic field. As a starting point, this treatment invokes the Vlasov equation instead of the traditional Fokker-Planck equation. Quasi-linear theory is applied to obtain a momentum diffusion equation for the heliocentric frame of reference which describes the interaction of cosmic rays with convecting magnetic irregularities in the solar-wind plasma. Under restricted conditions, the well-known equation of solar modulation can be obtained from this kinetic equation.
The paper describes the Lunar Ejecta and Meteorites (LEAM) experiment of the Apollo 17 flight mission, placed in the Taurus-Littrow area of the moon. The objective of the experiment was to measure impact parameters of cosmic dust on the lunar surface. Preliminary data analysis led to the recognition that the bulk of events recorded by the LEAM experiment are not signatures of hypervelocity cosmic dust particles as expected, but are induced signatures of electrostatically charged and transported lunar fines.
A principal cause for the eleven-year sunspot cycle variation in the primary cosmic ray intensity observed at earth may be a variation in the solid angle of the heliosphere occupied by the extended solar polar magnetic field. Galactic cosmic rays have relatively easy access to the inner solar system through the regular extended solar polar fields, and relatively difficult access through the irregular extended solar sector structure fields.
The origin of the Z greater than 28, ultraheavy, cosmic rays in supernova explosions of massive stars is considered. For Z greater than 70, the UH data is dominated by an r-process source distribution, but for the elements just beyond iron, 29 or = Z less than 36, the data cannot be explained by any single process of nucleosynthesis. This problem is solved naturally in a massive star model by secondary neutron capture reactions occuring during core helium burning and during explosive carbon burning. Interstellar propagation calculations were performed with these episodes of synthesis as source distributions, and the results offer an explanation for the current UH cosmic-ray data. The heavy element synthesis during explosive carbon burning is reexamined using more realistic initial conditions given by the post-helium-burning configuration of the star. Effects of preferential acceleration are considered, and experimental tests are discussed.
Results are reported for measurement of the intensity and energy spectrum of primary cosmic-ray electrons with a spark-chamber-counter-emulsion detector flown at a mean altitude of 3 g/sq cm residual atmosphere. A least-squares fit to the flight data yields an electron spectrum from 8 to 80 GeV of approximately 93E to the -2.91 power electrons/sq m/sec per sr/GeV. The results are compared with those of previous experiments as well as with the spectrum obtained for galactic nonthermal radiation. It is concluded that a 'clumpy' magnetic field proportional to the square root of matter density is consistent with measurements of high-energy electrons and synchrotron radiation toward the center of the Galaxy, that a gradual steepening of the electron spectrum relative to the proton spectrum is consistent with an electron lifetime of 1 million years, and that the density of cosmic-ray nucleons and electrons should be essentially uniform throughout the Galaxy if the nucleons have the same lifetime as the electrons and if they traversed 4 to 5 g/sq cm in that lifetime.
Gradient and curvature drifts in an Archimedean-spiral magnetic field are shown to produce a significant effect on the modulation of galactic cosmic rays by the solar wind. The net modulation, heliocentric radial gradient, and average energy change of particles which reach the inner solar system are significantly reduced. The effects of drifts are due to the fact that cosmic rays for which the drift velocity is comparable to the wind velocity or larger, have more rapid access to the inner solar system than in the absence of drifts.
The ability of heliomagnetic and geomagnetic fields to bring about climatic variations of long period is examined theoretically. A chemical relationship between low-energy cosmic rays and ozone balance in the stratosphere is sought as a crucial clue to historical changes in earth climate. A perturbation analysis is developed to arrive at zone depletion and reduction of stratospheric solar heating resulting from increased NOx concentration; temperature feedback and opacity feedback are allowed for. Modulation of galactic cosmic-radiation fluxes and ozone destruction in the stratosphere, colder surface temperatures associated with reduced magnetic shielding, and redistribution with height of total ozone decrease are explored.
A new detector for cosmic-ray electrons, consisting of a combination of a transition-radiation detector and a shower detector, has been constructed, calibrated at accelerator beams, and exposed in a balloon flight under 5 g/sq cm of atmosphere. The design of this instrument and the methods of data analysis are described. Preliminary results in the energy range 9-300 GeV are presented. The energy spectrum of electrons is found to be significantly steeper than that of protons, consistent with a long escape lifetime of cosmic rays in the galaxy.
Recent measurements of the mean lifetime of galactic cosmic rays (at least 10 million yr) have suggested a dynamical halo model of cosmic-ray confinement to the Galaxy. A one-dimensional version of the model is analyzed to determine the ranges of parameters required to give self-consistent values of the mean lifetime, matter traversed, anisotropy, and interstellar gamma-ray flux. It is found that the ranges of the parameters are: disk scale height of 4000-10,000 pc, average convection velocity of no more than 60 km/s, and diffusion coefficient of (3-10) by 10 to the 28th power sq cm/sec for particles with charges of the order of 10 GV. Some consequences for this model of a much shorter lifetime are also discussed. The energy spectrum and spatial distribution of electrons in the dynamical halo model are considered. A gradual steepening of the electron energy spectrum beginning at several GeV energy is found, as indicated by observations. The decrease of electron density with height in the halo depends on the particle energy and may be much steeper than that for nuclei. The models give a halo with a scale height of the order of 3 kpc for several-GeV electrons, which is shown to be consistent with radio observations.