Archaeology and Identity In the 19th Century Northern Cape Frontier: the Xhosa of the Pramberg

This dissertation examines the identity of the Xhosa communities that settled in the frontier zone of the Northern Cape during the first half of the 19th century. It does this through the archaeology, and ethnographic and historical accounts. The concept of a baseline Nguni identity in the Eastern Cape is examined with an emphasis on settlement, mobility and cultural interaction. The historical background and a brief history of the of the Xhosa in the Northern Cape will be detailed, focusing on the Pramberg community. The archaeology of three Xhosa sites in the Pramberg will be described and analysed, and then contrasted and compared with the ethnographic and historical evidence. The result of this comparison is a discussion of the identity change and continuity of the Pramberg Xhosa in the context of the cultural milieu of the frontier and the appropriation of land by the expanding Cape colony

Polarization observables in few nucleon systems with CLAS

The CEBAF Large Acceptance Spectrometer (CLAS), housed in Hall-B at the Thomas Jefferson National Accelerator Facility provides us with the experimental tools to study strongly-interacting matter and its dynamics in the transition from hadronic to partonic degrees of freedom in nuclear interactions. In this paper we discuss the progress made in understanding the relevant degrees of freedom using polarisation observables of deuteron photodisintegration in the few-GeV photon-energy region. We also address progress made in studying the interaction between Hyperons and Nucleons via polarisation observables, utilising high-statistics experiments that provided us with the large data samples needed to study final-state interactions, as well as perform detailed studies on initial-state effects. The polarisation observables presented here provide us with unique experimental tools to study the underlying dynamics of both initial and final-state interactions, as well as the information needed to disentangle signal from background contributions

Study of the Hyperon-Nucleon Interaction via Final-State Interactions in Exclusive Reactions

A novel approach that allows access to long-sought information on the Hyperon-Nucleon (YN) interaction was developed by producing a hyperon beam within a few-body nuclear system, and studying final-state interactions. The determination of polarisation observables, and specifically the beam spin asymmetry, in exclusive reactions allows a detailed study of the various final-state interactions and provides us with the tools needed to isolate kinematic regimes where the YN interaction dominates. High-statistics data collected using the CLAS detector housed in Hall-B of the Thomas Jefferson laboratory allows us to obtain a large set of polarisation observables and place stringent constraints on the underlying dynamics of the YN interaction

Study of the Hyperon-Nucleon Interaction in Exclusive Photoproduction off the Deuteron

The study of final-state interactions in exclusive hyperon photoproduction off the deuteron is a promising approach to extract information about the hyperon-nucleon (YN) interaction. First preliminary results on the azimuthal asymmetry ∑, as well as the polarization transfer coeffcients Ox, Oz, Cx, and Cz for the reaction γd → K+ Λn initiated with linearly and circularly polarized photon beam are presented. The data were taken with the CLAS detector in Hall B of Jefferson Lab during the E06-103 experiment. The large kinematic coverage of the CLAS, combined with the exceptionally high quality of the experimental data, allows identifying and selecting final-state interaction events to extract single- and double-polarization observables and their kinematical dependencies

Beam-spin asymmetry Σ\boldsymbol{\Sigma} for Σ−\Sigma^- hyperon photoproduction off the neutron

We report a new measurement of the beam-spin asymmetry $\boldsymbol{\Sigma}$ for the $\vec{\gamma} n \rightarrow K^+\Sigma^-$ reaction using quasi-free neutrons in a liquid-deuterium target. The new dataset includes data at previously unmeasured photon energy and angular ranges, thereby providing new constraints on partial wave analyses used to extract properties of the excited nucleon states. The experimental data were obtained using the CEBAF Large Acceptance Spectrometer (CLAS), housed in Hall B of the Thomas Jefferson National Accelerator Facility (JLab). The CLAS detector measured reaction products from a liquid-deuterium target produced by an energy-tagged, linearly polarised photon beam with energies in the range 1.1 to 2.3 GeV. Predictions from an isobar model indicate strong sensitivity to $N(1720)3/2^+$, $\Delta(1900)1/2^-$, and $N(1895)1/2^-$, with the latter being a state not considered in previous photoproduction analyses. When our data are incorporated in the fits of partial-wave analyses, one observes significant changes in $\gamma$-$n$ couplings of the resonances which have small branching ratios to the $\pi N$ channel.Comment: 9 pages, 4 figures, Hadron Spectroscop

From missionary to merino: Identity, economy and material culture in the Karoo, Northern Cape, South Africa, 1800 - ca. 1870

This thesis addresses the 19th century sequence of Kerkplaats, a farm in the central Karoo, Northern Cape, South Africa. Over this period different colonialisms of varying power and effect were introduced. The first was to local Khoe, San and Griqua communities in the form of one of the first London Missionary Society stations in the early 19th century. A second phase between 1830 and 1860 was to sheep farmers of German, Dutch and mixed descent, who absorbed and moulded the increasing impacts of British influence and materiality into older worlds of cultural resilience and practice. From 1860, a third phase saw a flood of mass produced British goods enter the region, similar to other colonial contexts around the world. Amount, availability and choice changed significantly and provided the material substrate in which rural stock farmers re-expressed themselves within the growing stature of Empire. It is suggested that for some rural farmers, expressive cultural practice worked to underpin increased affluence brought by merino sheep farming for global markets. Through this sequence different expressions of identity, domesticity, and economic scale are assessed through a close reading of documentary and archaeological evidence. While the material opportunities through the 19th century are the result of global processes, how this material is understood has to consider local context. It is suggested that material expression and identity change is most dramatic from the middle of the 19th century, when patterns of consumption reflect the globalisation of British production

Determination of the Azimuthal Asymmetry of Deuteron Photodisintegration in the Energy Region E{sub {gamma}} = 1.1 - 2.3 GeV

Deuteron photodisintegration is a benchmark process for the investigation of the role of quarks and gluons in nuclei. Existing theoretical models of this process describe the available cross sections with the same degree of success. Therefore, spin-dependent observables are crucial for a better understanding of the underlying dynamical mechanisms. However, data on the induced polarization (P{sub y}), along with the polarization transfers (C{sub x'} and C{sub z'} ), have been shown to be insensitive to differences between theoretical models. On the other hand, the beam-spin asymmetry {Sigma} is predicted to have a large sensitivity and is expected to help in identifying the energy at which the transition from the hadronic to the quark-gluon picture of the deuteron takes place. Here, the work done to determine the experimental values of the beam-spin asymmetry in deuteron photodisintegration for photon energies between 1.1 2.3 GeV is presented. The data were taken with the CLAS at the Thomas Jefferson National Accelerator Facility during the g13 experiment. Photons with linear polarization of ~80% were produced using the coherent bremsstrahlung facility in Hall B. The work done by the author to calibrate a specific detector system, select deuteron photodisintegration events, study the degree of photon polarization, and finally determine the azimuthal asymmetry and any systematic uncertainties associate with it, is comprehensively explained. This work shows that the collected data provide the kinematic coverage and statistics to test the available QCD-based models. The results of this study show that the available theoretical models in their current state do not adequately predict the azimuthal asymmetry in the energy region 1.1 2.3 GeV

Determination of the Azimuthal Asymmetry of Deuteron Photodisintegration in the Energy Region E_γ = 1.1 - 2.3 GeV

Deuteron photodisintegration is a benchmark process for the investigation of the role of quarks and gluons in nuclei. Existing theoretical models of this process describe the available cross sections with the same degree of success. Therefore, spin-dependent observables are crucial for a better understanding of the underlying dynamical mechanisms. However, data on the induced polarization (P{sub y}), along with the polarization transfers (C{sub x'} and C{sub z'} ), have been shown to be insensitive to differences between theoretical models. On the other hand, the beam-spin asymmetry {Sigma} is predicted to have a large sensitivity and is expected to help in identifying the energy at which the transition from the hadronic to the quark-gluon picture of the deuteron takes place. Here, the work done to determine the experimental values of the beam-spin asymmetry in deuteron photodisintegration for photon energies between 1.1 2.3 GeV is presented. The data were taken with the CLAS at the Thomas Jefferson National Accelerator Facility during the g13 experiment. Photons with linear polarization of ~80% were produced using the coherent bremsstrahlung facility in Hall B. The work done by the author to calibrate a specific detector system, select deuteron photodisintegration events, study the degree of photon polarization, and finally determine the azimuthal asymmetry and any systematic uncertainties associate with it, is comprehensively explained. This work shows that the collected data provide the kinematic coverage and statistics to test the available QCD-based models. The results of this study show that the available theoretical models in their current state do not adequately predict the azimuthal asymmetry in the energy region 1.1 2.3 GeV

Photodisintegration of Light Nuclei with CLAS

We report preliminary results of photodisintegration of deuteron and {sup 3}He measured with CLAS at Jefferson Lab. We have extracted the beam-spin asymmetry for the {vector {gamma}}d {yields} pn reaction at photon energies from 1.1 GeV to 2.3 GeV and proton center-of-mass (c.m.) angles between 35{degrees}#14; and 135{degrees}#14;. Our data show interesting evolution of the angular dependence of the observable as the photon energy increases. The energy dependence of the beam-spin asymmetry at 90#14; shows a change of slope at photon energy of 1.6 GeV. A comparison of our data with model calculations suggests that a fully non-perturbative treatment of the underlying dynamics may be able to describe the data better than a model based on hard scattering. We have observed onset of dimensional scaling in the cross section of two-body photodisintegration of {sup 3}He at remarkably low energy and momentum transfer, which suggests that partonic degrees of freedom may be relevant for the description of nuclei at energies lower than previously considered