The inelastic interactions of negative pi mesons with protons at 374, 417, and 454 Mev incident pi kinetic energy are studied by measuring the differential distributions of finalstate neutrons. The pi source is an internal target of the Berkeley 184-inch synchrocyclotron. A magnetic beamtransport system momentum-anaiyzes and focuses the pi beam at a liquid hydrogen target located in an adjacent shielded experimental area. The time-of- flight distribution of neutral particles is measured at various laboratorysystem angles between 10 and 65 deg. Neutral particles are detected by observing the charged products of their interactions in plastic scintillator. The time-of- flight information is determined electronically by time-to-height conversion and pulse-height analysis. The time resolution of the total system is 1.0 nsec. Detected neutral particles accompanied by charged particles are separated by the electronic system from those not accompanied by charged particles. Analysis presuming the principal inelastic reactions to be pi /sup -/p yields pi /sup +/ pi /sup -/n and pi /sup -/p yields pi /sup 0/ pi /sup 0/n separates the time-of-flight spectra into gamma rays, neutrons from the reaction pi /sup -/p yields pi /sup 0/n, and inelastic neutrons. Calculated values of the neutron- detection efficiency are used in the …

Effects due to elementary particle-like collisions within nuclear matter have been observed in several nuclear reactions caused by pions and protons. Simple nuclear reactions of the form ZA(a,an)Z/sup A-1/ and Z/sup A/(a,ap)(Z-1)/ sup A-1/ have excitation functions that are sensitive to changes in the elementary-particle cross sections. The excitation function for the reaction C/ sup 12/( pi /sup -/, pi /sup -/n)C/sup 11/ is measure d from 53 to 1610 Mev by bombarding targets of plastic scintillator with pions. The intensity of the pion beam is monitored with a two-counter telescope and 40 Mc scaling system. The scintillator target is mounted on a phototube and becomes the detector for the carbon-11 positron activity. Corrections are made for muon contamination in the beam, coincidence losses in the monitor system, carbon-11 activity produced by stray background at the accelerator, carbon-1l activity produced by secondaries in the target, and the efficiency of the carbon-11 detection system. The C/sup 12/( pi /sup -/, pi /sup -/n)C/sup 11/ cross sections rise to a peak of abo ut 70 mb at 190 Mev, that corresponds to the resonance in freeparticle pi /sup -/n scattering at 190 Mev. Calculations based on a knock-on'' collision mechanism and sharp-cutoff …

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Transport solutions to the monoenergetic plane, spherical, and cylindrical critical problems with isotropic scattering are developed by the method of singular expansion modes. The results are given in the form of exact expressions for the neutron distributions and criticality conditions. These expressions depend on expansion coefficients that are shown to satisfy Fredholm integral equations of the second kind. Successive approximations on the coefficients lead to the asymptotic results of diffusion theory as well as to easily accessible transport corrections. The expansions for the neutron distributions are derived by two different, but equivalent, methods. In the first method a three-dimensional expansion for the angular density is developed from the elementary solutions of the transport equation and then specialized to the desired geometry. For problems with plane symmetry, the resulting expression are used directly to determine the expansion coefficients, whereas in spherical and cylindrical geometries the specialization of the three-dimensional solutions yields a variety of representations for the respective angular densities. The second method consists of replacing the angular distributions by suitable density transforms and then determining the transforms completely with the aid of the integral equations for the neutron densities. In plane geometry this method leads to the conversion of the …

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The adiabatic single crystalline elastic constants of six Mg(Cu, Zn)/sub 2/ cubic Laves phases have been determined by the ultrasonic pulse-echo technique over the compositional range 10 to 50 mol % MgZn/sub 2/ and over the temperature range 4.2 to 300/sup 0/K. In addition the elastic constants of the hexagonal MgZn/sub 2/ Laves phase were measured as a function of temperature. A minimum exists in the compositional dependence of the cubic Mg(Cu, Zn)/sub 2/ phase at 20 mol % MgZn/sub 2/ for all three directly measured values and the anisotropy ratio shows a maximum at the same composition. These phenomena may be related to the fact that their Fermi surface touches the (311) faces of the Brillouin zones at this composition. The various energy contributions to the elastic shear constants were considered and it was concluded that the Fermi energy has to be included to achieve satisfactory agreement between the calculated and measured elastic constants. The Debye temperatures were calculated and were found to decrease at low zinc contents and then increase at compositions above 20 mol % MgZn/sub 2/ for the cubic Mg(Cu, Zn)/sub 2/ phase. The initial decrease is probably due to the substitution of the heavier zinc …

The purpose of this investigation is to determine the change in characterization that takes place in the works of Emilia Pardo Bazán. Source material include the writings of such critics of Spanish literature as Richard Chandler, Kessel Schwartz, Emiliano Díez-Echarri, José M. Roca Franquesa, Federico C. Saínz de Robles, and José A. Balseiro. Emilia Pardo Bazán wrote a total of twenty novels. From this collection ten were selected which best exemplify the change in characterization in her writings.

This thesis describes the design, selection and scale model test results of a contour design for a convectively-cooled, ground test nozzle extension which originates at an area ratio of 5:1 (termination point of main nozzle).

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Thesis. Exposure of rats to 700 rads whole-body /sup 60/Co gamma irradiation increased capillary permeabilily by 47% and increased lymph flow by 124% 48 hrs following irradiation, while exposure to 1000 rads caused an increase of capillary permeability of 98%, but did not change lymph flow from control values. The latter result may have been due to the relative dehydration and immobility of the 1000 rad group. Rats drinking large quantities of 5% dextrose + 0.7% NaCl solution did not increase lymph flow measurably above control levels. (CH)

Thesis. The electrical characteristics of In/I/In and In/I/Pb superconducting tunnel junctions have been studied in detail. Since In does not readily form pinhole free oxide layers, a thin insulating dielectric was formed on freshly deposited In film by passing an electric discharge through an atmosphere of fluorocarbon gas. Junctions were then completed by depositing a thin counter electrode of In or Pb. The same process was used to prepare high resistance junctions with Au as the base electrode; these were not however, studied in detail. In/I/In and In/I/Pb junctions were produced with resistances in the range 0.01 ohms to 10/sup 10/ ohms at liquid helium temperatures. Low resistance junctions exhibited nonlinear electrical characteristics associated with good quality oxide'' superconducting junctions including (a) the dc Josephson effcct, (b) quasiparticle tunneling characteristics. (c) phonon structure and (d) inelastic tunneling phenomena. The magnitude of the Josephson current for In/I/In junctions agreed to within a few percent of the value predicted by strong coupling theory. Current voltage (I-V) and first and second derivative curves for In/I/In and In/I/Pb were compared with curves for Al/I/In and Pb/I/Pb junctions. Discrepancies between the characteristics can be, for the most part, explained on the basis of existing theories …

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The nature of defects resulting from the implantation of phosphorous ions into doped silicon and a model of how they form are reported. This involved an electron microscope study of the crystallographic defects (in the 300A size range in concentration of 10$sup 15$/cm$sup 3$) that form upon annealing. Images formed by these crystallographic defects are complex and that nonconventional imaging techniques are required for their characterization. The images of these small defects (about 300A) are sensitive to various parameters, such as foil thickness, their position in the foil, and diffracting conditions. The defects were found to be mostly interstitial hexagonal Frank loops lying on the four [111] planes and a few perfect interstitial loops; these loops occurred in concentrations of about 10$sup 16$/cm$sup 3$. In addition, ''rod like'' linear defects that are shown to be interstitial are also found in concentrations of 10$sup 13$/cm$sup 3$. It was found that the linear defects require boron for their formation. A model is proposed to account for the interstitial defects. The number of point defects that make up the defects is of the same order as the number of implanted ions. The model predicts that only interstitial loops ought to be observed in …

The results of a measurement of the $pi$$sup -$p $Yields$ $pi$$sup 0$n and $pi$$sup -$p $Yields$ eta n differential cross sections at six pion beam momenta from 20 to 200 GeV/c are presented. The data for these cross sections were collected at the Fermi National Accelerator Laboratory in Batavia, Illinois. A 73.5 x 73.5 cm lead--scintillator hodoscope was used to detect the two photons from the decay of the $pi$$sup 0$ and the eta; all other reactions were eliminated by detection of their charged particles and additional photons in an array of veto counters. The zero-degree charge exchange cross sections determined from these measurements are shown to be consistent with the measured $pi$$sup +$p and $pi$$sup -$p total cross section differences. Effective Regge trajectories for the rho and the A$sub 2$ also extracted from the data. 34 figures, 9 tables. (auth)