Magnetic beta-ray spectrometers of several types have been used extensively to obtain information by the detection of low energy gamma-rays. The photoelectric effect, Compton scattering, and atomic internal conversion have yielded information regarding nuclei energy level spacings, transition schemes, relative and absolute intensities of gamma radiation, and the multipole character of nuclear radiation. However, these processes have low cross sections for high energy gamma rays, so that some other process is necessary for the study of the high energy region. Pair production, unlike the secondary processes mentioned, is increasingly probable at higher gamma ray energies. Useful information can be gained by the study of the pairs produced in the external, internal, and nuclear pair formation processes. Most generally, the total energy and number of the pairs detected are used to determine energy level spacings in nuclei, and to find what gamma ray transitions occur as well as the probability for their occurrence. A potentially fruitful field of study is opened by studying internal and nuclear pairs. Information concerning the multipole character of the radiation and consequently the angular momentum and parity changes in nuclear transitions can possibly be gained by the study of internal pair formation. Nuclear pairs immediately indicate the angular momenta of the excited levels from which they arise. This paper describes the development and use of a magnetic lens spectrometer for the detection of pairs. The spectrometer has been used as a medium resolution spectrometer for high energy gamma rays. It is capable of detecting either external, internal, or nuclear pairs. Measurements made using these three processes will be described.

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This thesis will be devoted to describing two rather different problems of nuclear physics which have been studied with the Rice University 180° magnetic spectrometer. The first part of the thesis describes a series of experiments which has been performed in an effort to obtain a set of energy standards which could be employed in calibrating analyzing magnets associated with various experimental nuclear physics problems. The second part of the thesis describes a study of the decay scheme for three-body nuclear decay. A recent paper by Phillips, Griffy, and Biedenharn has treated the three-body decay process as a time sequence of two-body interactions; and the cross section predictions resulting from this treatment have been investigated.

States in N14 in the region of excitation energy between 10.6 and 12.2 Mev have been studied by means of the C 13(p,n)N13, C13(p,d)C12, and C13(p,p1)C13* reactions. The C13(p,n)N13 total cross section has been measured from threshold, Eplab = 3.236, to 5.2 Mev in 30-kev steps by measuring the activation of the N13(half life = 10.1 min). The differential cross sections for the C13(p,d)C 12 and C13(p,p1)C13* reactions have been taken at center of mass angles near thetacm = 90° and 160°. This data along with that of Kashy et al., of the elastically scattered protons from C13 have been analyzed. Reaction-particle widths for the 11.05 (1+), 11.240 (3 -), 11.30 (2-), 11.39 (1+), and 11.503 (3+) states assigned from the elastic scattering data have been determined. Resonances at Eplab = 4.50 Mev (Gamma = 140 kev) 4.58 (Gamma = 60), 4.76 (Gamma = 320) and 5.04 (Gamma = 320) corresponding to levels at 11.72, 11.80, 11.96 and 12.22 Mev with assignments of 1-, 2+, 2 -, and 3- have also been investigated. Reaction particle-widths for these states have also been determined.

The importance of studying the radiations emitted by nuclei can be understood by considering the kind of information that can be obtained from such a study. Much information can be obtained with a pair spectrograph. The pair process is particularly suited for studying high energy (>3 Mev) transitions since pair production is increasingly probable at higher energies, and since this method makes possible the resolution of complicated spectra. The magnetic lens spectrometer is suited for pair measurements because of its large efficiency for transmitting pairs relative to most other types of spectrometers. Previous measurements have been made with magnetic lens pair spectrometers by Bame and Baggett (Ba 51a) and by D. E. Alburger (Al 52). The purpose of this work was to use a magnetic lens pair spectrograph of improved design to study the pair spectra from some light nuclear reactions. This paper describes a number of experiments which were performed to investigate the pair spectra resulting from the deuteron bombardment of B 10, C12, and F19, and the proton bombardment of B11 and F19. The apparatus and experimental techniques are described, and the results of the experiments are presented.

It is generally believed that many of the properties of solid bodies could be determined theoretically to very good approximation if it were possible to solve completely the Schrodinger wave equation for the motion of an electron in a solid. It is presupposed that the forces in solids are known, and that the effect of the lattice and other electrons on the motion of a single electron can be included in some periodic potential function having the periodicity of the lattice. Usually, this potential function is unknown, but the fact that it has the periodicity of the lattice is sufficient to determine many of the characteristic properties of the solid. We know that the wave function for the motion of an electron through the lattice is that of an infinite plane wave with a function having the lattice periodicity as amplitude, and that the corresponding energies are distributed in bands or zones, the structure of which is determined for each lattice by its particular periodicity.

In recent years an increasing number of nuclear reactions have been studied experimentally in which more then one nucleon is transferred from the bombarding particle to the target nucleus. The reactions studied are primarily those in which two nucleons are transferred from an incident three or four nucleon complex, for example (He3,p), (alpha,d), etc. The structure of the angular distributions seem to indicate that at high enough energies "direct" reaction mechanisms may be the predominant reaction process. In section I and II we formulate a plane wave Born Approximation direct reaction treatment of the general stripping reaction based on the work of W. Tobocman. Section III is devoted to reviewing the deuteron induced reactions using this formalism to make clear why tensor force and finite range effects are small in these reactions. The formalism is applied to the two nucleon stripping reaction, specifically the (He3,p) reaction in Chapter IV. To investigate the importance of tensor forces we need to know the properties of the 3-nucleon ground state wave function and of the residual nucleus wave function. A discussion of the 3-nucleon ground state is given in Chapter V and Appendix I. A simple L-S coupling shell model for the residual nucleus is used to give explicit expressions for the cross section in Chapter VI. Finally a discussion of the importance of the tensor force and the ramifications of our formalism are given in Chapter VII, for the reaction He4(He 3,p)Li6.

The velocity variation of the target areas of nuclei for neutrons has been investigated for neutrons obtained by bombardment of Be, B, and F with Po-alpha-particles. The target area of hydrogen was found to increase rapidly with a decrease in the velocity of the neutrons. The target area of carbon and nitrogen also increased with a decrease in the velocity of the neutrons, but not so rapidly as did that of hydrogen. The absorption of neutrons by lead was found to increase with the velocity. This anomalous absorption of lead can be explained by assuming that faster neutrons make relatively more inelastic collisions with the nuclei. Cosmic-ray bursts can be explained on the basis of this assumption. The neutrons from fluorine were found to be slower than those from boron, and the average range of the recoil protons produced by them was estimated to be about 2 cm in air. These slower neutrons were found to be more penetrating in lead than those from either beryllium or boron.

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