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The aim of this thesis is to increase our knowledge and understanding of trace water concentrations in nominally anhydrous minerals (NAMs). Special focus is put on the de- and rehydration mechanisms of clinopyroxene crystals in volcanic systems, how these minerals can be used to investigate the volatile content of mantle rocks and melts on both Earth and other planetary bodies (e.g., Mars). Various analytical techniques for water concentration analysis were evaluated. The first part of the thesis focusses on rehydration experiments in hydrogen gas at 1 atm and under hydrothermal pressures from 0.5 to 3 kbar on volcanic clinopyroxene crystals in order to test hydrogen incorporation and loss from crystals and how their initial water content at crystallization prior to dehydration may be restored. The results show that extensive dehydration may occur during magma ascent and degassing but may be hindered by fast ascent rates with limited volatile loss. De- and rehydration processes are governed by the redox-reaction OH- + Fe2+ ↔ O2- + Fe3+ + ½ H2. Performing rehydration experiments at different pressures can restore the water contents of clinopyroxene at various levels in the volcanic systems. Subsequently water contents of magmas and mantle sources can be deduced based on crystal/melt partition coefficients. This thesis provides examples from the Canary Islands, Merapi volcano in Indonesia and the famous Nakhla meteorite. Using NAMs as a proxy for magmatic and mantle water contents may provide a very good method especially for planetary science where sample material is limited. The thesis’ second part focusses on analytical methods to measure the concentration of water in NAMs. Specifically the application of Raman spectroscopy and proton-proton scattering are tested. The hydrated mineral zoisite is thoroughly analyzed in order to be used as an external standard material. Polarized single crystal spectra helped to determine the orientation of the OH-dipole in zoisite. Further, Transmission Raman spectroscopy and a new method for the preparation of very thin samples for proton-proton scattering were developed and tested. The results provide new possibilities for the concentration analysis of water in NAMs such as three dimensional distribution and high spatial resolution.

The Q-weak experiment at Thomas Jefferson National Accelerator Facility (USA) will make a precision determination of the proton weak charge with approximately 4% combined statistical and systematic uncertainties via a measurement of the parity violating asymmetry in elastic electron-proton scattering at very low momentum transfer and forward angle. This will allow an extraction of the weak mixing angle at Q^2=0.026 (GeV/c)^2 to approximately 0.3%. The weak mixing angle is a fundamental parameter in the Standard Model of electroweak interactions. At the proposed accuracy, a measured deviation of this parameter from the predicted value would indicate new physics beyond what is currently described in the Standard Model. Without deviation from the predicted value, this measurement would place stringent limits on possible extensions to the Standard Model and constitute the most precise measurement of the proton's weak charge to date. The key experimental apparatus include a liquid hydrogen target, a toroidal magnetic spectrometer and a set of eight Cerenkov detectors. The Cerenkov detectors form the main detector system for the Q-weak experiment and are used to measure the parity violating asymmetry during the primary Q-weak production runs. The Cerenkov detectors form the main subject of this thesis. Following a brief introduction to the experiment, the design, development, construction, installation, and testing of this detector system will be discussed in detail. This is followed by a detailed discussion of detector diagnostic data analysis and the corresponding detector performance. The experiment has been successfully constructed and commissioned, and is currently taking data. The thesis will conclude with a discussion of the preliminary analysis of a small portion of the liquid hydrogen data.

The Q-weak experiment at Thomas Jefferson National Accelerator Facility (USA) will make a precision determination of the proton weak charge with approximately 4% combined statistical and systematic uncertainties via a measurement of the parity violating asymmetry in elastic electron-proton scattering at very low momentum transfer and forward angle. This will allow an extraction of the weak mixing angle at Q^2=0.026 (GeV/c)^2 to approximately 0.3%. The weak mixing angle is a fundamental parameter in the Standard Model of electroweak interactions. At the proposed accuracy, a measured deviation of this parameter from the predicted value would indicate new physics beyond what is currently described in the Standard Model. Without deviation from the predicted value, this measurement would place stringent limits on possible extensions to the Standard Model and constitute the most precise measurement of the proton's weak charge to date. The key experimental apparatus include a liquid hydrogen target, a toroidal magnetic spectrometer and a set of eight Cerenkov detectors. The Cerenkov detectors form the main detector system for the Q-weak experiment and are used to measure the parity violating asymmetry during the primary Q-weak production runs. The Cerenkov detectors form the main subject of this thesis. Following a brief introduction to the experiment, the design, development, construction, installation, and testing of this detector system will be discussed in detail. This is followed by a detailed discussion of detector diagnostic data analysis and the corresponding detector performance. The experiment has been successfully constructed and commissioned, and is currently taking data. The thesis will conclude with a discussion of the preliminary analysis of a small portion of the liquid hydrogen data.

Under current investigation is the re-implementation of the Distorted-Wave Impulse Approximation (DWIA), originally formulated in FORTRAN by N.S. Chant and P.G. Roos, with the intention of developing it in a portable Python environment. This will be complimented by developing a GEANT4 detector simulation application. These two techniques will be used to model the (p,2p) proton knock-out reaction 40Ca(p; 2p)39K (2.52 MeV)1 2 + first excited state, at intermediate incident energies of 150 MeV. This study is a test-bed that lays the foundation and platform from which one may develop an interactive workbench and toolkit in GEANT4 which: (i.) accurately models an accelerator-detector experimental set-up, such as those found at iThemba Labs, and (ii.) incorporates the DWIA formalism as a built-in physics process within the framework of GEANT4. Furthermore the Python modules developed for the specific proton knock-out reaction studied here, can be generalized for an arbitrary set of nuclear scattering reactions and packaged as a suite of scientific Python codes. / Theoretical and Computational Nuclear Physics / M. Sc. (Theoretical and Computational Nuclear Physics)

Under current investigation is the re-implementation of the Distorted-Wave Impulse Approximation (DWIA), originally formulated in FORTRAN by N.S. Chant and P.G. Roos, with the intention of developing it in a portable Python environment. This will be complimented by developing a GEANT4 detector simulation application. These two techniques will be used to model the (p,2p) proton knock-out reaction 40Ca(p; 2p)39K (2.52 MeV)1 2 + first excited state, at intermediate incident energies of 150 MeV. This study is a test-bed that lays the foundation and platform from which one may develop an interactive workbench and toolkit in GEANT4 which: (i.) accurately models an accelerator-detector experimental set-up, such as those found at iThemba Labs, and (ii.) incorporates the DWIA formalism as a built-in physics process within the framework of GEANT4. Furthermore the Python modules developed for the specific proton knock-out reaction studied here, can be generalized for an arbitrary set of nuclear scattering reactions and packaged as a suite of scientific Python codes. / Theoretical and Computational Nuclear Physics / M. Sc. (Theoretical and Computational Nuclear Physics)

Die vorliegende Arbeit beschreibt die Messung der polarisierten Strukturfunktion g1p des Protons in der polarisationsabh"angigen tief inelastischen Positron-Proton-Streuung bei einer Schwerpunktenergie von 7.5 GeV. Die Analyse umfasst die 1997 mit dem Hermes-Experiment am Hera-Positronring aufgezeichneten Daten der Streuung polarisierter Positronen der Energie 27.6 GeV an einem polarisierten Wasserstofftarget. Aus den Z"ahlraten der inklusiv nachgewiesenen, selektierten Positronen f"ur die parallele und die antiparallele Ausrichtung der Spinvektoren von Strahlteilchen und Targetatomen wurde die Streuquerschnitts- Asymmetrie der Positron-Proton-Streuung bestimmt. In verschiedenen Korrekturverfahren wurden Untergrundprozesse, Spektrometereinfl"usse sowie Strahlungskorrekturen ber"ucksichtigt. Die Untergrundkorrekturen wurden aus den Daten, die Spektrometerkorrekturen aus einer Monte-Carlo- Simulation ermittelt. Die Abh"angigkeit der Monte-Carlo- und Strahlungskorrekturen von der gew"ahlten Modell-Asymmetrie zur Beschreibung der polarisationsabh"angigen Effekte wurde durch die Anwendung eines iterativen Verfahrens minimiert. Aus der vollst"andig korrigierten Streuquerschnitts-Asymmetrie wurde die Asymmetrie g1/F1 im kinematischen Bereich 0.021 < x < 0.85 und Q2 > 0.8 GeV^2 mit einer systematischen Unsicherheit von etwa 8% bei einer statistischen Genauigkeit von 6% bis 20%, ansteigend f"ur abnehmende x-Werte, bestimmt. Die aus g1/F1 berechnete polarisierte Strukturfunktion g1p(x,Q2) wird, unter der Annahme einer von q2 unabh"angigen Asymmetry g1/F1, zu einem festen Wert Q2_0 entwickelt. Ihr erstes Moment im gemessenen x-Bereich betr"agt int_{0.021}^{0.85} dx g1p(x,Q2_0) = 0.122 =- 0.003 (stat) =- 0.010 (sys) at Q2_0 = 2.5 GeV^2. Der Vergleich mit den Werten des SMC-Experimentes am CERN und des E143-Experimentes am SLAC f"ur das erste Moment von g1p wurde unter Anwendung des gleichen Integrationsschemas f"ur den jeweils gemeinsam gemessenen x-Bereich sowie f"ur gleiche Q2_0 Werte durchgef"uhrt. Das Ergebnis der vorliegenden Analyse befindet sich, bezogen auf die statistische Genauigkeit der Messungen, in "Ubereinstimmung innerhalb von 0.6 bzw. 1.2 Standardabweichungen mit den Resultaten des E143- bzw. SMC-Experimentes. Durch Extrapolation der Strukturfunktion auf den gesamten x-Bereich [0,1] wird das erste Moment zu \int_{0}^{1} dx g1p(x,Q2_0) = 0.132 +- 0.003 (stat) +- 0.010 (sys) +- 0.006 (extr) bestimmt, wobei der zus"atzliche Fehler die Unsicherheit in der Extrapolation x -> 0 wiedergibt. Die Interpretation der vorliegenden Messung im Rahmen des Quark-Parton-Modells unter Ber"ucksichtigung von QCD-Korrekturen der Ordnung O(alphaS^3) ergibt einen Beitrag der Quarks zum Gesamtspin des Nukleons von (30 +- 10)% f"ur Q2_0 = 2.5 GeV^2. Dieses Ergebnis entspricht einer Abweichung von der Ellis-Jaffe-Vorhersage um 2.5 Standardabweichungen, bezogen auf den angegebenen Gesamtfehler, und f"uhrt im Kontext des Quark-Parton-Modells zur Interpretation negativ polarisierter Strange-Seequarks mit einem Beitrag von (-9 +- 4)% f"ur Q2_0 = 2.5 GeV^2. Von verschiedenen Gruppen werden aus QCD-Analysen unterschiedlicher Datens"atze Beitr"age der Quarks zum Nukleonspin von 19% bis 44% angegeben. Unter Hinzunahme der Hermes-Messung der polarisierten Neutronstrukturfunktion g1n wurde der Wert der fundamentalen Bjorken-Summenregel f"ur Q2_0 = 2.5 GeV^2 bestimmt. Dieser Wert befindet sich, bei einer auf den Gesamtfehler bezogenen Genauigkeit von 13%, innerhalb von 0.5 Standardabweichungen in "Ubereinstimmung mit der theoretischen Vorhersage, berechnet unter Ber"ucksichtigung von QCD-Korrekturen der Ordnung O(\alphaS^3). / The subject of this thesis is the measurement of the polarised structure function g1p of the proton in deeply inelastic positron-proton-scattering at a centre of mass energy of 7.5 GeV. The data used in the analysis were recorded during the 1997 running period of the Hermes experiment using a longitudinally nuclear polarised hydrogen target in the 27.6 GeV Hera polarised positron storage ring. The cross section asymmetry of positron-proton-scattering has been measured by counting the number of inclusively reconstructed and selected positrons with target spin vector parallel or antiparallel to the beam spin direction. Background processes, spectrometer effects, and radiative corrections have been taken into account by applying different correction procedures. Here background corrections were determined from data while spectrometer corrections were computed from Monte Carlo simulation. The dependence of Monte Carlo and radiative corrections on the model asymmetry chosen to describe polarisation dependent effects has been minimised by applying an iterative procedure. From the fully corrected cross section asymmetry the asymmetry g1/F1 has been computed in the kinematic region 0.021 < x < 0.85 and Q2 > 0.8 GeV^2 with a systematic uncertainty of 8% and a statistical accuracy of 6% to 20%, raising for decreasing x values. The polarised structure function g1p(x,Q2), determined from the asymmetry g1/F1 , was evoluted to a common Q2_0 value assuming g1/F1 to be independent of Q2. Its first moment evaluated in the measured x region is int_{0.021}^{0.85} dx g1p(x,Q2_0) = 0.122 =- 0.003 (stat) =- 0.010 (sys) at Q2_0 = 2.5 GeV^2. This result has been compared with those from E143 at SLAC and from SMC at CERN, both calculated with the same integration scheme and for the kinematic range of Hermes. With respect to the statistical uncertainties the agreement is better than 0.6 and 1.2 standard deviations, respectively. Extrapolation over the entire x range [0,1] yield for the first moment\int_{0}^{1} dx g1p(x,Q2_0) = 0.132 +- 0.003 (stat) +- 0.010 (sys) +- 0.006 (extr) where the additional error gives the uncertainty in the extrapolation x -> 0. The interpretation of this measurement in the framework of the quark parton model taking QCD corrections of the order O(alphaS^3) into account results in a contribution of the quarks to the total nucleon spin of (30 +- 10)% at Q2_0 = 2.5 GeV^2. This result corresponds to a deviation from the Ellis-Jaffe prediction by 2.5 standard deviation regarding the given total uncertainty. Within the quark parton model the deviation can be interpreted as negative polarisation of the strange sea quarks with a contribution of (-9 +- 4)% at Q2_0 = 2.5 GeV^2. Different groups give contributions of the quarks to the nucleon spin of 19% to 44% which were obtained from QCD analyses of various data sets. The fundamental Bjorken sum rule has been determined at Q2_0 = 2.5 GeV^2 using the Hermes measurement of the polarised neutron structure function g1n. With respect to the experimental accuracy of 13 %, the result agrees within 0.5 standard deviation with the theoretical prediction taking QCD corrections of the order O(alphaS^3) into account.

Les études de structure et de spectroscopie réalisées sur les noyaux radioactifs durant les trois dernières décennies ont montré que la structure en couches des noyaux évolue vers la drip-line et que de nouveaux nombres magiques peuvent apparaître. Les noyaux doublement magiques sont très rares mais ils représentent des tests très contraignants pour les théories et leur modélisation de l'interaction nucléaire.Dans ce contexte, nous avons étudié la structure et la spectroscopie du noyau doublement magique d'oxygène 24, situé à la drip-line neutron, via la diffusion élastique et inélastiques de protons (p,p'). L'expérience a été effectuée à RIKEN sur la ligne BigRIPS, avec le faisceau de noyaux d'oxygène 24 produit à 263 MeV/n par RIBF à une intensité inégalée (1780/s), et le détecteur de particules chargées de dernière génération MUST2. L'analyse des données de cette thèse a permis de reconstruire : le spectre en énergie d'excitation du noyau d'oxygène 24 jusqu'à 35 MeV à partir de la cinématique des protons diffusés en utilisant la méthode de la masse manquante, et la distribution angulaire entre 4 et 30 degrés c.m. de la section efficace élastique exclusive (p,p) via une triple coïncidence noyau-proton-noyau. Sous le seuil de séparation de deux neutrons (S2n) la statistique est trop faible pour obtenir les deux états excités mesurés par deux expériences menées à plus basse énergie incidente. Au dessus du S2n des structures sont observées pour la première fois grâce à la gamme étendue accessible en énergie d'excitation. La mesure des états excités situés à ces énergies permettrait de tester les études théoriques menées sur les excitations dipolaires de basse énergie des noyaux légers riches en neutrons. La statistique obtenue pour la diffusion élastique de protons est suffisante pour extraire la distribution angulaire exclusive (p,p) des isotopes d'oxygène 24,23,22,21. Ces résultats constituent une référence inédite pour étudier le potentiel d'interaction proton-noyau autour de 260 MeV/n. La comparaison entre les données élastiques et les calculs de réaction réalisés à partir d'un potentiel microscopique, dépendant de la densité du noyau et construit avec la matrice G, nous indique que ce potentiel est satisfaisant; mais que l'inclusion, dans un futur modèle en voies couplées à haute énergie, de l'élastique et du knockout de quelques neutrons apparaît nécessaire. Les rayons quadratiques moyens des derniers isotopes pair-pair liés d'oxygène ont pu être estimés : rm(22O)=3+-0.1 fm et rm(24O)=3.25+-0.2 fm. / The studies of structure and spectroscopy performed on radioactive nuclei during the last three decades have shown that the nuclear shell structure changes towards the drip-line and local magic numbers may appear. Doubly-magic nuclei are very rare but represent stringent tests for theories and their modelling of the nuclear interaction.In this context, we have investigated the structure and spectroscopy of the drip-line doubly-magic nucleus 24O via proton elastic and inelastic scattering (p,p'). The experiment was performed at RIKEN in the BigRIPS line, using the 24O beam produced at 263 MeV/n with RIBF with a high intensity (1780/s), and the state-of-the-art MUST2 charged particle detector. The analysis of the data gives the reconstruction of : the 24O excitation energy spectrum up to 35 MeV with the scattered proton kinematics using the missing mass method, and the angular distribution of exclusive (p,p) elastic cross section between 4 and 30 degrees c.m. via a triple coincidence nucleus-proton-nucleus. Below the two-neutron separation threshold (S2n) the statistics is too low to obtain the two excited states measured by previous experiments done at lower incident energies. Above the S2n structures are observed for the first time due to the large excitation energy range of the excitation spectra. The measurement of the excited states located at these energies would allow to test theoretical studies of low-energy dipole excitation in light neutron-rich nuclei. The statistics obtained for proton elastic scattering is sufficient to extract the exclusive (p,p) angular distributions of the 24,23,22,21O isotopes. These results constitute a new benchmark to explore proton-nucleus interaction potential features around 260 MeV/n. The comparison of elastic data set to the reaction calculations done with the microscopic reaction approach based on the G-matrix density-dependent potential indicates that this potential is suitable. However, it remains to include both the elastic and the knockout reactions in a future complete coupled channel reaction model at high energy. The root-mean-square radii of the two last bound even-even isotopes have been estimated: rm(22O)=3+-0.1 fm et rm(24O)=3.25+-0.2 fm.

The 14N(p,gamma)15O reaction is the slowest stage of the carbon-nitrogen-oxygen cycle of hydrogen burning and thus determines its reaction rate. Precise knowledge of its rate is required to improve the model of hydrogen burning in our sun. The reaction rate is a necessary ingredient for a possible solution of the solar abundance problem that led to discrepancies between predictions of the solar standard model and helioseismology. The solar 13N and 15O neutrino fluxes are used as independent observables that probe the carbon and nitrogen abundances in the solar core. This could settle the disagreement, if the 14N(p,gamma)15O reaction rate is known with high precision. After a review of several measurements its cross section was revised downward due to a much lower contribution by one particular transition, capture to the ground state in 15O. The evaluated total relative uncertainty is still 7.5%, in part due to an unsatisfactory knowledge of the excitation function over a wide energy range. The present work reports experimentally determined cross sections as astrophysical S-factor data at twelve energies between 0.357 - 1.292 MeV for the strongest transition, capture to the 6.79 MeV excited state in 15O with lower uncertainties than before and at ten energies between 0.479 - 1.202 MeV for the second strongest transition, capture to the ground state in 15O. In addition, an R-matrix fit is performed to estimate the impact of the new data on the astrophysical relevant energy range. The recently suggested slight S-factor enhancement at the Gamow window could not be confirmed and differences to previous measurements at energies around 1 MeV were observed. The present extrapolated zero-energy S-factors are S_6.79(0) = (1.19+-0.10) keV b and S_GS(0) = (0.25+-0.05) keV b and they are within the uncertainties consistent with values recommended by the latest review. / Die 14N(p,gamma)15O Reaktion ist die langsamste Phase im Bethe-Weizsäcker-Zyklus des Wasserstoffbrennens und bestimmt deshalb die Reaktionsrate des gesamten Zyklus. Präzise Werte für die Reaktionsrate sind notwendig um das Wasserstoffbrennen in unserer Sonne besser zu verstehen. Besonders das Problem widersprüchlicher Ergebnisse aus Vorhersagen des aktuellen Sonnenmodells und helioseismologischen Experimenten könnte durch genauer bekannte 14N(p,gamma)15O Reaktionsraten aufgelöst werden. Dafür soll der solare 13N und 15O Neutrinofluss von den beta+-Zerfällen als direkter Informationsträger über die Häufigkeit von Stickstoff und Kohlenstoff im Sonneninneren genutzt werden. Der für die Berechnung der Häufigkeiten benötigte Wirkungsquerschnitt der 14N(p,gamma)15O Reaktion wurde in einer Evaluation verschiedener Messungen reduziert, da der Anteil des direkten Protoneneinfang mit Übergang in den Grundzustand deutlich weniger zum gesamten Wirkungsquerschnitt beiträgt als zuvor angenommen. Die evaluierte relative Gesamtunsicherheit ist mit 7.5% dennoch hoch, was zu einem großen Teil an ungenügendem Wissen über die Anregungsfunktion in einem weiten Energiebereich liegt. In der vorliegenden Arbeit werden experimentell ermittelte Wirkungsquerschnitte in Form von astrophysikalischen S-Faktoren für zwei Übergänge vorgestellt. Für den stärksten Übergang, den Protoneneinfang zum angeregten Zustand bei 6.79 MeV in 15O, wurden zwölf S-Faktoren bei Energien zwischen 0.357 – 1.292 MeV mit geringeren Unsicherheiten als zuvor ermittelt und für den direkten Übergang in den Grundzustand zehn Werte zwischen 0.479 – 1.202 MeV. Außerdem wurde ein R-Matrix Fit durchgeführt um den Einfluss der neuen Daten auf Extrapolationen zum astrophysikalisch relevanten Energiebereich zu prüfen. Die kürzlich vorgeschlagene Erhöhung des S-Faktors im Gamow-Fenster konnte nicht bestätigt werden und es wurden auch Unterschiede zu bisherigen Messungen im Energiebereich um 1 MeV deutlich. Die neuen extrapolierten S-Faktoren sind S679(0) = (1.19±0.10) keV b und SGS(0) = (0.25 ± 0.05) keV b und sie stimmen mit den von der Evaluation empfohlenen Werten im Rahmen ihrer Unsicherheiten überein.