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Full-Text Articles in Physics
Investigation Of The Superconducting Properties Of Niobium Radio-Frequency Cavities, Gianluigi Ciovati
Investigation Of The Superconducting Properties Of Niobium Radio-Frequency Cavities, Gianluigi Ciovati
Physics Theses & Dissertations
Radio-frequency (rf) superconducting cavities are widely used to increase the energy of a charged particle beam in particle accelerators. The maximum gradients of cavities made of bulk niobium have constantly improved over the last ten years and they are approaching the theoretical limit of the material. Nevertheless, rf tests of niobium cavities are still showing some "anomalous" losses (so-called "Q-drop"), characterized by a marked increase of the surface resistance at high rf fields, in absence of field emission. A low temperature "in-situ" baking under ultra-high vacuum has been successfully applied by several laboratories to reduce those losses and …
Inclusive And Exclusive Compton Processes In Quantum Chromodynamics, A. Psaker
Inclusive And Exclusive Compton Processes In Quantum Chromodynamics, A. Psaker
Physics Theses & Dissertations
In our work, we describe two types of Compton processes. As an example of an inclusive process, we consider the high-energy photoproduction of massive muon pairs off the nucleon. We analyze the process in the framework of the QCD parton model, in which the usual parton distributions emerge as a tool to describe the nucleon in terms of quark and gluonic degrees of freedom. To study its exclusive version, a new class of phenomenological functions is required, namely, generalized parton distributions. They can be considered as a generalization of the usual parton distributions measured in deeply inelastic lepton-nucleon scattering. Generalized …