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An experiment has been carried out at the bevatron on the nuclear fragmentation of nitrogen-14 ions at an energy of 2.1 billion electron volts (Gev) per nucleon. Because of the near equality of the velocities of the nitrogen-14 beam and the fragmentation products at an angle of 0 deg, we find it possible to identify the nuclear fragments isotopically.
Calculation of nonelastic interactions corresponding to continuum-state transitions using the intranuclear-cascade evaporation approach. Spallation yields, energy- and angle-dependent spectra, particle multiplicities, and nonelastic cross sections are calculated for incident nucleons and pi mesons with energies below 3 GeV on complex nuclei. Comparisons with experimental data are made, and, in general, the agreement is good. Discrepancies in these comparisons are discussed with respect to the deficiencies in the model.
Sloan's conclusion (1969) that terms of the multiple-scattering series beyond single scattering contribute only to S- and P-wave amplitudes in an S-wave separable model is examined. A comparison of experiments with the calculation at 146 MeV shows that the conclusion is valid in nucleon-deuteron scattering applications.
Approximate solutions of the coupled-channel equations for high-energy composite particle scattering are obtained and are applied to the nuclear scattering problem. Relationships between several approximation procedures are established and discussed. The eikonal formalism is used with a small-angle approximation to calculate the coherent elastic scattered amplitude from which total and absorption cross sections are derived. Detailed comparisons with nucleon-nucleus experiments show agreement within 5 percent except at lower energies where the eikonal approximation is of questionable accuracy. Even at these lower energies, agreement is within 15 percent. Tables of cross sections required for cosmic heavy-ion transport and shielding studies are presented.
Corotating proton and electron streams are the dominant type of low-energy (i.e., 0.1-10 MeV per nucleon) particle event observed at 1 AU. The radial dependence of these events has been studied between 1 and 4 AU using essentially identical low-energy detector systems on IMP-7, Pioneer-10, and Pioneer-11. It had been expected that at a given energy, the intensity of these streams would decrease rapidly with heliocentric distance due to the effects of interplanetary adiabatic deceleration. Instead, it is observed that from event to event, the intensity either remains roughly constant or increases significantly (more than an order of magnitude) between 1 and 4 AU. It appears that interplanetary acceleration processes are the most plausible explanation. Several possible acceleration models are discussed.
Observations of the low energy quiet-time interplanetary nucleon spectrum obtained by Explorer 47 are examined for March 9-12, 1973, the quietest period from Sept. 26, 1972 through Feb. 15, 1975. The quiet-time energy spectrum may be represented by a power law with an index of about -3.1. The H/He ratio below 2 MeV is about 10. The ratio of antisunward to sunward intensities is about 2.6, increasing to about 8.55 in a frame moving with the solar wind. The angular distributions show that in the 0.3-0.5 MeV range most of the proton intensity originates in the earth's magnetosphere. The spectral behavior and enhancement of proton counting rates during microbursts suggest that the magnetosphere is a significant source at energies up to 2 MeV. The observed intensities are lower than those reported by Simpson and Tuzzolino (1973) by factors of 3 to 10. It is suggested that the low energy upturn in the quiet-time interplanetary proton spectrum may be related to particle emissions from planetary magnetospheres, such as that of Jupiter.
The paper presents a model of high-energy hadron-hadron scattering where each hadron is a fully absorbing scatterer with a radius that increases with energy. The energy dependence of the radius is chosen such that the total cross section has the energy behavior of the Froissart bound (which means that the cross sections are rising to infinity). The model is used to obtain amplitudes for pion-nucleon scattering.
To investigate the relationship between solar activity and cosmic-ray modulation, time series of the nucleonic flux and of solar plages, sunspots, centimeter radio noise, and the brightness of the white-light corona at 1.1 and 1.5 solar radii from the center of sun are cross-correlated. Data pertain to the years 1964-1967 during the ascending phase of the current solar cycle. The amplitudes and phases of correlation functions for filtered and unfiltered indices are discussed. The existence of a superior solar index for relating solar activity to long-term modulation is not yet demonstrated conclusively, and the time lag of modulation is too poorly determined to permit its use in estimating the radius of the modulation region.
A description is given of an experiment which was designed to measure the spectra and composition of cosmic-ray hydrogen and helium isotopes in the interval 120-280 MeV per nucleon to compare with the recent values observed at low energies and also with the only earlier measurement in this high-energy regime. The results presented were obtained during a high-altitude balloon flight from Thompson, Manitoba, in 1973 August. This flight occurred during the period in which the presence of the anomalous component in the helium spectrum became apparent, and provides the opportunity of determining whether this component extends to higher energies than those studied by satellite experiments. The results place an upper limit on the flux of 'anomalous' He-4 (which appeared at low energy in 1972) of at most 15% in the energy range of this experiment, and combined with the low-energy observations of the Chicago group, show an energy dependence of the average ratio of the helium isotopes in the modulated cosmic rays which is difficult to reconcile with current modulation models.
Utilizing an optical model potential approximation to the exact nucleus-nucleus multiple-scattering series, optical potentials for nucleon-nucleus and nucleus-nucleus collisions are analytically derived. These expressions are applicable to light and medium cosmic ray nuclei as their single-particle density distributions are analytically determined, without approximation, from their actual harmonic well charge density distributions. Pauli correlation effects are included through the use of a simple Gaussian function to replace the usual expression obtained in the infinite nuclear matter approximation.
Attention is given to the combined, average effects of the bow shock and magnetosheath on the diffusive flow of interplanetary nuclei. The observations presented show that differences between 'connected' and 'unconnected' data subsets are apparent from the beginning of the analysis. Through an investigation of the mean unconnected diffusive anisotropy (those fluxes least affected by the earth's bow shock and magnetosheath) it is confirmed that the cross-field transport of MeV energy nuclei in interplanetary space is statistically significant and in the direction expected from the large-scale particle flux gradients. The direction of particle flow relative to the IMF is then used to show that nucleon flow characteristics on connected IMF differ from those on unconnected IMF. A scenario for producing this difference is then presented. It is concluded that the inclusion of the bow shock connected information biases measurements of the flux anisotropies of MeV energy H.
A survey of the roughly 1 MeV per nucleon ion abundance over the range H-Fe measured with 3 hr time resolution during large solar particle events from November 1973 through December 1977, under near solar minimum conditions, is presented. For all the monitored species, a strong decrease in average flux level occurred with increase of the optical flare site distance from the W 60 deg connection point. The 3 hr abundance ratios He/H, O/He, and Fe/He were observed to fluctuate by a factor of about two about their average values for given flare events, and the size of these fluctuations was independent of the distance to the optical flare site. The monitored abundance ratios exhibited no dependence on distance to the optical flare site. The physical mechanism suggested to explain these observations is large-scale shock acceleration from a shock wave originating at the flare site and propagating as far away as 100 deg heliolongitude.
Observations of the flux of nuclei with an energy of IO MeV per nucleon on the Salyut-7 Station in September 1984 are presented. The observed flux is smaller by a factor of 50 than the flux detected in May, 1981.
The analysis of experimental data on hadron-nucleus collisions at energies from about 2 up to about 400 GeV was performed in order to discover a physical meaning of the multiplicity of emitted nucleons. Simple relations between the multiplicities and the thickness of the nuclear matter layer involved in collisions were obtained.
The separation of the gamma families generated in nucleon-nuclear and pion-nuclear (PI-A) interactions is realized from the analysis of simulated gamma families. Some characteristics of NA and PI families and the influence of the process of inelastic charge-exchange of charged pions neutral ones type of PI + or - A yields are studied.
The KGF nucleon decay experiment has been in operation since October 1980 with a 140 ton calorimetric detector at a depth of 2.3 Km underground. The detector comprises 34 layers of proportional counters arranged in an orthogonal geometry with 12 mm thick iron plates in between successive layers. The proportional counters are made up of square (10 x 10 square centimeters) iron plates of wall thickness 2.3 mm. Each of the 1600 counters is instrumented to provide data on ionization, DE/dx and arrival time. The visible energy of a particle is determined to an accuracy of approximately 20% from the ionization and range of its track. The end point ionization of a stopping track provides the direction of motion as well as the nature of the particle (mu/pi,k,p). Decay of mu is recorded with an overall efficiency of only 20% in view of the thickness of 13 g/square centimeters between successive layers.
A simplified model of nucleon-nucleus reaction is developed and some of its properties are examined. Comparisons with proton production measured for targets of Al-27, Ni-58, Zr-90, and Bi-209 show some hope for developing an accurate model for these complex reactions. It is suggested that binding effects are the next step required for further development.
A hybrid electronic-counter/emulsion-chamber instrument was exposed to high-energy cosmic rays on a balloon. The data on 105 nucleus-nucleus collisions in the energy range 20-65 GeV/nucleon and for incident nuclear charges Zp in the range of 22 to 28 are presented. Inclusive characteristics of particle production on different targets (plastic, emulsion, and lead) are shown and compared with models based on the superposition of nucleon-nucleus interactions. Features of a subset of the more central collisions with a plastic target and some characteristics of individual events with the highest multiplicity of produced particles are described.