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Accelerator mass spectrometry (AMS) has been used routinely for radiocarbon measurements for several years. During this period it has become evident neither the accuracy nor the range of the technique were as great as had originally been hoped. This thesis describes both theoretical work to understand the reasons for this and practical solutions to overcome some of the problems. The production and transport of the ions used in the measurements are found to be the most crucial stages in the process. The theories behind ion production by sputtering are discussed and applied to the specific case of carbon sputtered by caesium. Experimental evidence is also examined in relation to the theories. The phenomena of space charge and lens aberrations are discussed along with the interaction between ion beams and gas molecules in the vacuum. Computer programs for calculating phase space transformations are then described; these are designed to help investigations of the effects of space charge and aberrations on AMS measurements. Calculations using these programs are discussed in relation both to measured ion beam profiles in phase space and to the current dependent transmission of ions through the Oxford radiocarbon accelerator. Improvements have been made to this accelerator and these are discussed in the context of the calculations. There are many reasons for wishing to produce C^- ions directly from carbon dioxide. The most suitable type of source for achieving this is the Middleton High Intensity Sputter Source. Experiments to evaluate the performance of such a source are described and detailed design criteria established. An ion source designed and built specifically for radiocarbon measurements using carbon dioxide is described. Experiments to evaluate its performance and investigate the underlying physical processes are discussed. The source is found to have a high efficiency enabling small samples (<100 μg of carbon) to be measured. The cross contamination is measured to be low (<0.1%) and the background currents are small; the implications of these results are discussed.

We determine the parton distributions of the pion from a consistent next-to-leading order analysis of several high statistics π±N experiments including both Drell-Yan and prompt photon production. The results are compared with earlier distributions and with the predictions of lattice QCD. We study the general behaviour of parton distributions at small x and, in particular, the predictions of the Lipatov equation. The very-small-a; behaviour of the gluon distribution in a proton is obtained by solving this equation with a suitable nonlinear shadowing term incorporated. We find, with decreasing x, the emergence of an x(^- λ) behaviour one? the eventual taming of this singular behaviour by the shadowing term. We compare our dynamically generated gluon distribution with (i) the results of a recent next-to-leading order QCD structure function analysis which incorporated both a singular behaviour and shadowing corrections, (ii) the double-leading-leading logarithm approximation (DLLA) and (iii) the semiclassical approximation of the DLLA. Finally, we examine the proposal that deep-inelastic scattering events which contain an identified jet, with transverse momentum squared k(^2) ~Q(^2) allow an ideal determination of the QCD behaviour at very small x. We solve the relevant Lipatov equation to predict the shape of the jet spectrum in such events and discuss whether it will be possible to observe such jets at the HERA collider.

The theory of Inelastic Neutron Scattering (INS) Spectroscopy is outlined, and the spectrometers employed in the study of low frequency (< 1500cm(^-1)) vibrations of hydrogen-containing molecules described. Square planar platinum-ethylene complexes of the general form trans-PtCl(_2)(C(_2)H(_4)).L and cis-PtCl(_2)C(_2)H(_4)).L (where L is a Ligand) have been investigated by INS spectroscopy, and assignments made of their spectra below 850cm(^-1). In all cases, a frequency was found representing the torsion of the ethylene group about an axis projected from the platinum atom through the centre of the C=C band, and the barrier to this rotation calculated. INS active modes of Co(_2)(CO)(_6).C(_2)H(_2) (O-1450cm(_1)) have been tentatively, identified, and a value for the barrier to the rotation of the acetylene molecule about an axis running through the mid-points of the Co-Co and C=C bonds derived. INS spectra of C(_2)H(_4) and C(_2)D(_4), adsorbed at two overpressures onto silver exchanged type A (Ag(_12)A) zeolite have been measured. On this basis of deuteration shifts and relative intensities, all three torsional modesand two of the three translational modes expected for the ethylene moleculerelative to a silver ion have been assigned. In addition, several weak spectroscopic features appeared to indicate the presence of a secondless populated adsorption site. C(_2)H(_2) and C(_2)D(_2) adsorbed onto Ag(_12)A zeolite at one overpressure have been studied by INS spectroscopy. All six predicted acetylene-surface modes were observed, the presence of the torsional vibration of the acetylene molecule about an axis running parallel to the C=C bond indicating the adsorbed molecule to be non-linear. Finally , INS spectra of the complexes Cr(C(_6)H(_6))(_2), Cr(C(_6)H(_6)(_2)I, C(_6)H)(_6)Cr(CO)(_3) and C(_6)H(_6)Mn(CO)(_3) Br have been recorded in the region 0-900(^1). Assignments have been attempted and, wherever possible, the barrier to the rotation of the benzene ligand (s) about the six - fold axis calculated.

Next-to-leading order QCD fits are performed to F(_2)(^up), F(_2)(^un)/F(_2)(^up), F(_2)(^uFe) and xF(_3)(^vFe) deep-inelastic scattering data using the F^^ data of either the EMC or BCDMS collaborations, appropriately renormalized for consistency with the re- analysed SLAC F(_2)(^ep) data. The parton distributions from these fits are then used to predict next-to- leading order prompt photon production cross-sections. The variation in the quality of the overall description of the deep-inelastic scattering and prompt photon production data simultaneously determines A(_MS) and the form of the gluon distribution of the proton. Next, cross-sections are predicted at next-to-leading order for the Drell-Yan process. Here, the quality of the overall description determines the antiquark content of the proton. Two sets of parton distributions are presented according to whether the EMC or BCDMS F(_2)(^up) data were used in the analysis. Possible alternatives for the low-x behaviour of the gluon distribution - outside the range of the fitted data - are discussed and predictions are made for future experiments which have the potential to distinguish between these alternatives.

The formalism for a helicity amplitude analysis of the exclusive semileptonic decays of B mesons (B → Dlv and B → D* lv for l = e, µ and r) is introduced. In particular it is shown how measurements of the angular distribution of the subsequent decay D* → Dπ can fully determine the theoretically uncertain hadronic (B → D,D*) matrix elements. A spectator quark based model for the hadronic amplitudes is introduced, and then compared to other existing models and with the presently available experimental data, to extract the quark mixing matrix element |V(_eb)|. The extraction of |V(_ub)|, using exclusive models for b → u decays, is also discussed. The predictions of the free-quark model of inclusive semileptonic B decays are compared with those of the exclusive models, in an attempt to test the reliability of the inclusive model's predictions for |V(_eb)| and |V(_ub)|. A phenomenological analysis of experimental measurements of K(^0) – K(^0) and B(^0) – B(0) mixing is made, incorporating the above determinations of the mixing matrix elements, with a view to constraining the parameters of the standard model, such as the mass of the top-quark.

No description available.

No description available.

No description available.