Thesis (Ph. D.)--University of Wisconsin--Madison, 1975. / Typescript. Vita. Description based on print version record. Includes bibliographical references (leaves 120-122).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1969. / Typescript. Vita. Description based on print version record. Includes bibliographical references.

Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 186-190).

The yields of the reactions 12C(α, α ')12C* to the T=0 state at 12.71 MeV (Jπ=1+ ) and the T=l state at 15.11 MeV (Jπ=1+ ) were measured by detecting the decay of these levels to the ground state by gamma emmission. A 90° (lab) yield curve from threshold to Eα= 27.0 MeV was obtained for each reaction. Both states have to be populated via an unnatural parity process and in addition the population of the 15.11 MeV level is isospin forbidden. Nevertheless, excitation of both levels is unambiguously detected. Although the ratio of the yields has a considerable energy dependence ( 1%<̲δ15.11/ δ 12.71<̲ 20%), conclusive evidence is shown for the breaking of isospin in l60*(Ex = 24.0 to 27.3 MeV). The 15.11 MeV yield curve had considerable structure, suggesting the formation of interimmediate states in 16₀* . While the yield of the 12.71 MeV gamma ray also showed evidence of structure, it was not as . dramatic as the 15.11 MeV gamma ray. The yield of the reaction 10B(a ,dy)12C* to the 12.71 and 15.11 levels was also measured. If the outgoing particle is a true deuteron and not an unbound n-p pair, the population of the i5.ll is isospin forbidden. Contrary to the 15.11 and 12.71 yields in 12C(a , a’)12C*f no resonant structure was found ln either the 12.71 or 15.11 yields; it is suggested that the reactions proceed through an isospin allowed sequence. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

Baryons are considered in the Nonrelativistic Quark Model (NQM) to be bound states of three valence quarks. Each quark has two possible spin eigenstates in the restframe of the baryon whose spin is fully carried by quarks. The baryon wavefunctions are connected through SU(6) symmetry rotations. For a long time, the measured magnetic moments of the baryons appeared to be in agreement with the NQM predictions. However, recent experiments which are examining the spin structure of the baryons show the failure of several NQM predictions. The so-called 'spin crisis' arose from the interpretation of the EMC deep inelastic scattering measurement of ∫ g^p₁ that the quark spins in the proton appeared to sum up to (almost) zero. In this thesis it will be demonstrated that the spin problem is not a phenomenon restricted to quasi-massless current quarks in the high energy limit. Symmetry arguments are used to examine the baryon magnetic moments and reveal that we can observe massive but pointhke constituent quarks, with a characteristic mass ratio m_u = m_d ≃ ²andfrasl;₃m_s. Surprisingly they do not contribute much to the baryon spin either. This analysis is free of the ambiguity arising from the UA(1} gluon anomaly which makes it impossible to calculate precisely the spin sum of the current quarks. One important finding in our analysis is the observation that the effects of SU(6) breaking hyperfine spin-spin interactions (which cause well-known splittings in the baryon masses) can be seen in the environment dependence of the constituent quark masses. The effective mass of a quark cannot be independent of its surrounding energy since the mass of the baryon is distributed amongst its constituents. Consistent with the hypothesis that different quark masses do not impose SU(3) breaking on the baryon wavefunctions is the observation of induced 'second class' form factors. The way in which SU(3) breaking alters the ^g_Aandfrasl;_{g_V} ratios in semileptonic hyperon decays will be discussed and strong evidence for a new value of F/D is given, which is close to its SU(6) value. This value is derived independently from the baryon β-decays <strong>and</strong> from their magnetic moments. Dynamical models are discussed which might explain the observed polarised strangeness 'inside' the proton, and the almost vanishing quark spin sum.

No description available.

Thesis (Ph.D.)--University of California, Berkeley, 1962. / "UC-34 Physics" -t.p. "TID-4500 (17th Ed.)" -t.p. Includes bibliographical references (p. 67-69).

Thesis (Ph. D.)--University of Wisconsin--Madison, 1970. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliography.