Analytic formulas for the rapid evaluation of the orbit response matrix and chromatic functions from lattice parameters in circular accelerators

Measurements and analysis of orbit response matrix have been providing for decades a formidable tool in the detection of linear lattice imperfections and their correction. Basically all storage- ring-based synchrotron light sources across the world make routinely use of this technique in their daily operation, reaching in some cases a correction of linear optics down to 1% beta beating and 0.1% coupling. During the design phase of a new storage ring it is also applied in simulations for the evaluation of magnetic and mechanical tolerances. However, this technique is known for its intrinsic slowness compared to other methods based on turn-by-turn beam position data, both in the measurement and in the data analysis. In this paper analytic formulas are derived and discussed that shall greatly speed up this second part. The mathematical formalism based on the Lie algebra and the resonance driving terms is extended to the off-momentum regime and explicit analytic formulas for the evaluation of chromatic functions from lattice parameters are also derived. The robustness of these formulas, which are linear in the magnet strengths, is tested with different lattice configurations

Studies and measurements of linear coupling and nonlinearities in hadron circular accelerators

In this thesis a beam-based method has been developed to measure the strength and the polarity of corrector magnets (skew quadrupoles and sextupoles) in circular accelerators. The algorithm is based on the harmonic analysis (via FFT) of beam position monitor (BPM) data taken turn by turn from an accelerator in operation. It has been shown that, from the differences of the spectral line amplitudes between two consecutive BPMs, both the strength and the polarity of non-linear elements placed in between can be measured. The method has been successfully tested using existing BPM data from the SPS of CERN, since presently the SIS-18 is not equipped with the necessary hardware. The magnet strength of seven SPS extraction sextupoles was measured with a precision of about 10%. The polarities have been unambiguously measured. This method can be used to detect polarity errors and wrong power supply connections during machine commissioning, as well as for a continuous monitoring of the "nonlinearity budget" in superconducting machines. A second beam-based method has been studied for a fast measurement and correction of betatron coupling driven by skew quadrupole field errors and tilted focusing quadrupoles. Traditional methods usually require a time-consuming scan of the corrector magnets in order to minimize the coupling stop band |C|. In this thesis it has been shown how the same correction can be performed in a single machine cycle from the harmonic analysis of multi-BPM data. The method has been successfully applied to RHIC. It has been shown that the stop band |C| (also known in the American literature as Delta-Qmin) measured in a single machine cycle with the new algorithm is compatible with the value obtained by traditional methods. The measurement of the resonance phase Theta defines automatically the best corrector setting, which was found in agreement with the one obtained with a traditional scan. A third theoretical achievement is a new description of the betatron motion close to the difference resonance in presence of linear coupling. Compared to the matrix formalism the motion is parametrized as a function of the resonance driving term f1001 only (which is proven to be an observable), whereas making use of the matrix approach four parameters need to be measured. Formulae describing the exchange of RMS emittances when approaching the resonances have been already derived in the 70s in the smooth approximation. New formulae have been derived here making use of Lie algebra providing a better description of the emittance behavior. The emittance exchange curves are predicted by new formulae with excellent agreement with multi-particle simulations and the counter-intuitive emittance variation along the ring of the emittance is proven to be related to the variation of f1001. A new way to decouple the equations of motion and explicit expressions for the individual single particle invariants have been found. For the first time emittance exchange studies have been carried out in the SIS-18 of GSI. Transverse RMS emittances have been measured during 2005 from rest gas monitor (RGM) data. Crossing the linear coupling resonance, the transverse emittances exchange completely. It has been observed that this effect is reversible. Applications of this manipulation are: emittance equilibration under consideration for future operations of the SIS-18 as booster for the SIS-100; emittance transfer during multi-turn injection to improve the eficiency and to protect the injection septum in high intensity operations, by shifting part of the horizontal emittance into the vertical plane. The emittance exchange curves obtained experimentally have been compared with analytic formulae providing a fast measurement (in few machine cycles only) of the linear coupling stop band |C|. Technical problems prevented the use of the eight skew quadrupoles installed in the SIS-18 to compensate the linear coupling resonance. It has been observed that the emittance exchange curve is highly sensitive to the beam intensity. Multi-particle simulations with 2D PIC space-charge solver have been run to infer heuristic scaling laws able to quantify the observable stop band, to be used for the resonance compensation. The analysis of BPM and RGM data has been performed making use of new software applications developed for this purpose. The bpm2rdt code for the harmonic analysis of BPM data has been written and tested with real data. The software reads the BPM turn-by-turn data and the Twiss parameters. Then it performs the FFT of these data, finds the peaks of the Fourier spectra and infers the RDT fjklm, the strengths ^hjklm and the local terms lambda-jklm. All these observables are printed out together with the corresponding values of the model, computed from the nominal values of strengths and the Twiss parameters. From the FFT of dual-plane BPM data the linear optics (beta functions and phase advances Delta phi) at the corresponding location is also inferred. From the measurement of f1000, the linear coupling coeffcient C (amplitude and phase) is also computed. The code has been tested by using existing SPS data and new RHIC data. For the on-line analysis of RGM data the rgm2emitt code has been written. The application reads in input the raw data files from the RGM and the beam loss monitor (BLM) respectively, the latter created by the RGM on-line software itself. From the RGM data the transverse beam sizes and emittances are inferred and used together with the BLM data to compute the tune shift during the machine cycle.Im Rahmen dieser Arbeit wurden drei Hauptaspekte untersucht, die die Strahlphysik von hadronischen Kreisbeschleunigern betreffen: - Entwicklung einer neuen strahlbezogenen Methode für die Messung der Nichtlinearitäten und der Kopplung zwischen den Betatron-Schwingungen; - Untersuchung des von der Betatron-Kopplung und Raumladung getriebenen Austauschs der transversalen Emittanzen - Entwicklung einer schellen Technik für die Korrektur der Betatron-Kopplung und für die Kontrolle des transversalen Emittanz-Austauschs

Realizzazione e caratterizzazione di microbilance risonanti basate su un processo CMOS-compatibile

In questa tesi sono state realizzate e caratterizzate microbilance risonanti, compatibili con la tecnologia CMOS, per rivelazioni chimiche di tipo gravimetrico. Il funzionamento di questi dispositivi è basato su un’attuazione magnetica in risonanza, mediante un momento torcente, creato da una coppia di forze di Lorentz. La rivelazione si basa similmente sulla f.e.m. indotta nella spira d’uscita a causa delle sue oscillazioni nello stesso campo magnetico d’attuazione. La sensitività si basa invece sullo spostamento della frequenza di risonanza, che è collegato alla variazione del momento d’inerzia della loro struttura, non appena essa adsorbe le molecole cercate. Nel primo capitolo sono presentati vari tipi di sensori chimici compatibili con la tecnologia CMOS. Un occhio di riguardo è dato ai MEMS per analisi su DNA, ma anche alle microbilance al quarzo, per le loro ottime caratteristiche, sebbene non siano compatibili con la tecnologia CMOS. Nel secondo capitolo sono presentati i sensori realizzati. Dopo una loro descrizione geometrica e delle principali proprietà, sono illustrati i passi di post-processing necessari al loro rilascio. Il terzo capitolo è dedicato infine alle misure svolte sui dispositivi per estrarne le caratteristiche principali, quali la frequenza di risonanza ed il fattore di qualità

Valutazione dell'azione di materiali contenenti additivi fotocatalitici su inquinanti ambientali tipici

La presenza di fotocatalizzatori in materiali edilizi o in pitture produce effetti autopulenti o addirittura di parziale o completa degradazione di tipici inquinanti (NOx, incombusti, etc). Fondamentale è la verifica di tali effetti attraverso la messa a punto di sistemi di prova adeguati ed oggettivi. La tesi si propone apppunto di giungere a formulare un protocollo di prova che consente di accettare e quantificare l'azione fotocatalitica dei materiali in argomento

Well-posedness of a mathematical model for Alzheimer's disease

We consider the existence and uniqueness of solutions of an initial-boundary value problem for a coupled system of PDE's arising in a model for Alzheimer's disease. Apart from reaction diffusion equations, the system contains a transport equation in a bounded interval for a probability measure which is related to the malfunctioning of neurons. The main ingredients to prove existence are: the method of characteristics for the transport equation, a priori estimates for solutions of the reaction diffusion equations, a variant of the classical contraction theorem, and the Wasserstein metric for the part concerning the probability measure. We stress that all hypotheses on the data are not suggested by mathematical artefacts, but are naturally imposed by modelling considerations. In particular the use of a probability measure is natural from a modelling point of view. The nontrivial part of the analysis is the suitable combination of the various mathematical tools, which is not quite routine and requires various technical adjustments

'Auntie Mame' di Patrick Dennis. Ipotesi a proposito delle potenzialita' di un testo letterario una volta svincolato dalla forma-libro.

Questa tesi vuole essere una possibile risposta alla domanda “che forma assume un testo letterario una volta che è stato svincolato dalla forma-libro, che non può che essere storicamente connotata?”. Come testo su cui fare questa riflessione è stato scelto per le sue caratteristiche “Auntie Mame” di Patrick Dennis, pseudonimo di Edward Everett Tanner III. Dopo una breve panoramica sulla biografia dell’autore, si espone e la struttura del romanzo e se ne analizza il contenuto: trama, personaggi, stile letterario, genere, contestualizzazione storica, adattamenti teatrali e cinematografici, successo editoriale (di quest’ultima voce si pone particolare attenzione al caso editoriale delle ristampe italiane). Si fa una panoramica sull’ipertesto e la sua genesi, in particolare in riferimento alle teorie di Ted Nelson, dopodiché si descrive la procedura di lavoro che portato a creare il documento allegato. In breve, è stato realizzato un ipertesto html che accede ad un file xml annotato secondo la codifica TEI Lite; nel file xml sono presenti i primi capitoli dell’edizione originale inglese, della traduzione italiana del 1956 e della traduzione italiana del 2009. Si analizzano le nuove possibilità offerte dal mezzo, tra cui la possibilità di essere messo in condivisione su piattaforme quali Wikia. (per visualizzare il progetto: installare EasyPhp, presente nell’archivio .rar, dopodiché sostituire la cartella www che si crea con l’installazione con quella nell’archivio