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An experimental study of the low lying excited states of C¹¹ has been made using the B¹⁰(d ,nɣ )C¹¹ reaction at a deuteron bombarding energy of 0.8 Mev. Measurements were made of the n- ɣangular correlations of the ground state gamma transitions from the 6.49 and 4.32 Mev levels, and of the gamma ray branching ratios of the 6.49, 4.81 and 4.32 Mev levels. The apparatus used for the measurements was a combination of a NaI(T1) gamma ray spectrometer and an improved fast neutron time-of-flight spectrometer, developed by the author. Theoretical analysis of the n-ɣ angular correlations showed that the 6.49 Mev and 4.32 Mev levels are formed by the capture of p½ protons This restricts the Jπ values of these levels to (5/2)¯ or (7/2)¯. The parities of the states observed in this experiment are all known to be negative from the high energy stripping data of Cerineo and Maslin et al. A comparison of the experimental branching ratios with the theoretical branching ratios predicted by the intermediate coupling shell model is consistent with the following spin and parity assignments in C¹¹ : g.s. (3/2)¯, 2.00 Mev (1/2)¯, 4.32 Mev (5/2)¯, 4.81 Mev (3/2*)¯ and 6.49 Mev (7/2)¯. These assignments are in agreement with other recent results. The correspondence of these levels in C¹¹ with those of B¹¹ is consistent with the hypothesis of the charge independence of nuclear forces. The experimental results agree in some cases and disagree in others with the intermediate coupling shell model calculations of Kurath. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The reaction D(p, γ )He³ was studied at incident proton energies of less than 50 kev. The method was to bombard heavy ice targets with the proton beam from the 50 kv accelerator. This machine develops an intense beam of 60 to 80 microamps which is necessary to produce a substantial yield despite the low reaction cross section. The angular distribution of the γ-rays was found to follow a (sin²θ +B) pattern as expected from earlier work carried out at higher energies. In the neighborhood of 35 kev the value of B was found, by measurements of the yield at 90° and at 0° to the incident beam direction, to be .283± .110. The total cross section was found to take on the following values: [In column] E(kev), 29.1, 37.5 44.0 ; [In column] σ(cm² ) x 10⁻³², 4.87 ± 1.05, 11.2 ± 2.8, 12.0 ± 4.0 / Science, Faculty of / Physics and Astronomy, Department of / Graduate

A study of the T(α,ɤ)Li⁷ reaction has been made at mean alpha particle energies of 1320, 560 and 350 Kev in a solid tritium-zirconium target. At the 1320 Kev energy the absolute 90° differential cross-section for transitions to the ground state has been found to be 1.89x10⁻³¹ cm² per steradian from analyses of spectra obtained in a 2¾"x4½” NaI crystal. At this energy the ratio of the differential cross-section for transitions to the first excited state to that for transitions to the ground state was found to be 0.446. This ratio was observed to remain the same at all detector angles. The excitation function roughly determined by additional runs at 560 and 350 Kev mean energy followed the form obtained by Riley of this laboratory in 1958. Angular distribution measurements at 1320 Kev gave the result that both the above mentioned gamma rays have the same angular dependence, this being 1-0.11 cos² θ + 0.39 cos⁴ θ. At 560 Kev mean energy their anisotropy was measured to be about 5%. A background from the target has been found to have an angular distribution at 1320 Kev mean alpha particle energy of 1+0.35 cos θ in laboratory co-ordinates. Both its excitation function, determined roughly from runs at 560 and 350 Kev, and its anisotropy followed a form in agreement with neutron counter measurements. It is suggested that this background is caused by neutrons from some still unknown reaction in the target. An investigation was also made of a standard thick-walled brass Geiger-Muller counter to determine its efficiency for photon energies from 0.5 to 20 Mev. A smooth curve was obtained showing efficiency increasing with gamma ray energy thus agreeing in form with previous experimental and theoretical results. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

The purpose of this paper is to study the possible excited states in the nucleus of Cs133. At North Texas State College a 100-Kev Cockcroft-Walton accelerator has been constructed for use as a neutron source for exciting various nuclei and for studying the gamma spectra obtained to determine their energy levels.

This paper is concerned with the design, testing and performance of a coincidence system, the proposed North Texas State College accelerator.

<p> This thesis is divided into two parts, the first part being devoted to the application of Neutron Capture Gamma Ray Analysis in determining S/Si and Fe/Si ratios in Allende meteorite and lunar samples and the second part, to evidence for a possible iron isotopic anomaly in the Allende meteorite obtained by the same method. The samples were irradiated in an in-core irradiation system in the McMaster swimming-pool nuclear reactor and the collimated beam of gamma rays was detected by a pair-spectrometer consisting of a Ge(Li) detector and NaI annulus. In the first part, besides the mainstream of the work, the basic principles of Neutron Capture Gamma Ray Analysis and Neutron Activation Analysis and the supremacy of the former over the latter for this particular problem has been discussed. In the second part, along with the implications and evidence of isotopic variations of other elements in the Allende meteorite, a brief description of the classification, structure and mineralogy of the Allende meteorite is given. The success and advantage of the method along with its limitations and further directions along these lines are also discussed.</p> / Thesis / Master of Science (MSc)

<p> The decay of 3.5 minute 89Kr to levels in 89Rb has been investigated with small and large volume Ge(Li) detectors used singly and in coincidence. A total of 160 gamma rays have been attributed to the nuclear process, 120 of which have been incorporated into a proposed decay scheme.</p> / Thesis / Master of Science (MSc)

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