Study of the X(3872) state with the CMS experiment at LHC

The surprising discovery of the X(3872) resonance by the Belle experiment in 2003, and subsequent confirmation by BaBar, CDF and D0, opened up a new chapter of QCD studies and puzzles. Since then, detailed experimental and theoretical studies have been performed in attempt to determine and explain the proprieties of this state. Since the end of 2009 the world’s largest and highest-energy particle accelerator, the Large Hadron Collider (LHC), started its operations at the CERN laboratories in Geneva. One of the main experiments at LHC is CMS (Compact Muon Solenoid), a general purpose detector projected to address a wide range of physical phenomena, in particular the search of the Higgs boson, the only still unconfirmed element of the Standard Model (SM) of particle interactions and, new physics beyond the SM itself. Even if CMS has been designed to study high energy events, it’s high resolution central tracker and superior muon spectrometer made it an optimal tool to study the X(3872) state. In this thesis are presented the results of a series of study on the X(3872) state performed with the CMS experiment. Already with the first year worth of data, a clear peak for the X(3872) has been identified, and the measurement of the cross section ratio with respect to the Psi(2S) has been performed. With the increased statistic collected during 2011 it has been possible to study, in bins of transverse momentum, the cross section ratio between X(3872) and Psi(2S) and separate their prompt and non-prompt component.

An experimental and theoretical approach to correct for the scattered radiation in an X-ray computer tomography system for industrial applications

The main problem connected to cone beam computed tomography (CT) systems for industrial applications employing 450 kV X-ray tubes is the high amount of scattered radiation which is added to the primary radiation (signal). This stray radiation leads to a significant degradation of the image quality. A better understanding of the scattering and methods to reduce its effects are therefore necessary to improve the image quality. Several studies have been carried out in the medical field at lower energies, whereas studies in industrial CT, especially for energies up to 450 kV, are lacking. Moreover, the studies reported in literature do not consider the scattered radiation generated by the CT system structure and the walls of the X-ray room (environmental scatter). In order to investigate the scattering on CT projections a GEANT4-based Monte Carlo (MC) model was developed. The model, which has been validated against experimental data, has enabled the calculation of the scattering including the environmental scatter, the optimization of an anti-scatter grid suitable for the CT system, and the optimization of the hardware components of the CT system. The investigation of multiple scattering in the CT projections showed that its contribution is 2.3 times the one of primary radiation for certain objects. The results of the environmental scatter showed that it is the major component of the scattering for aluminum box objects of front size 70 x 70 mm2 and that it strongly depends on the thickness of the object and therefore on the projection. For that reason, its correction is one of the key factors for achieving high quality images. The anti-scatter grid optimized by means of the developed MC model was found to reduce the scatter-toprimary ratio in the reconstructed images by 20 %. The object and environmental scatter calculated by means of the simulation were used to improve the scatter correction algorithm which could be patented by Empa. The results showed that the cupping effect in the corrected image is strongly reduced. The developed CT simulation is a powerful tool to optimize the design of the CT system and to evaluate the contribution of the scattered radiation to the image. Besides, it has offered a basis for a new scatter correction approach by which it has been possible to achieve images with the same spatial resolution as state-of-the-art well collimated fan-beam CT with a gain in the reconstruction time of a factor 10. This result has a high economic impact in non-destructive testing and evaluation, and reverse engineering.

I regesti delle carte bolognesi dei secc. X-XII trascritti nei cartulari ecclesiastici del XVII-XVIII secolo. Edizione critica

La ricerca ha come oggetto l’edizione critica di circa tremila regesti di documenti di area bolognese datati al X-XII secolo. I documenti sono stati trascritti tra il XVII e XVIII secolo in undici cartulari ecclesiastici, conservati presso l’Archivio di Stato di Bologna. Il lavoro s’inserisce nel progetto di edizione delle carte bolognesi di epoca medievale in corso presso la cattedra di Paleografia latina e Diplomatica dell’Università di Bologna, attualmente incentrata sull’edizione delle carte del secolo XII. La ricerca si propone come strumento di supporto a tale progetto e come completamento delle carte già pubblicate: i cartulari, infatti, offrono spesso copie di documenti mancanti dell’originale o in cattivo stato di conservazione, e costituiscono l’unica traccia di una memoria storica altrimenti perduta. Le raccolte esaminate si collocano a ridosso del periodo napoleonico, quando la maggior parte degli enti ecclesiastici venne soppressa e i loro beni incamerati dallo Stato; esse quindi rispecchiano la condizione dei principali archivi ecclesiastici cittadini dei primi secoli del Medioevo bolognese. La ricerca è strutturata in una prima parte volta a definire in termini storico-diplomatistici la tipologia di fonte esaminata: oggi i cartulari non sono più intesi come semplici raccoglitori di documenti, ma come sistema organico di fonti in grado di far luce su aspetti importanti della storia dell’ente che li ha prodotti. L’indagine del loro contesto di produzione permette di comprenderne meglio le finalità, la forma e il valore giuridico. Parte della ricerca è stata poi incentrata sullo studio delle ragioni che hanno portato gli istituti religiosi bolognesi alla redazione dei cartulari: a tal fine è stata esaminata la legislazione ecclesiastica cinque-settecentesca in materia di conservazione della documentazione e il rapporto della legislazione stessa con la prassi archivistica. Infine è stata realizzata l’edizione critica vera e propria dei regesti, mirante a descrivere le caratteristiche principali di ciascun cartulario.