HIGH ENERGY PHYSICS

Author: CAZÓN BOADO LORENZO.
Year: 2004.
University: SANTIAGO DE COMPOSTELA.
Place of defense: FACULTADE DE FÍSICA.
Place of preparation: FACULTADE DE FÍSICA.

Summary: The Cosmic Ray of the most altals energies (1E20 eV) are of particular interest for Physics: human accelerators are even today several orders of magnitude below that scale energía.Por other hand interaction with the microwave background produces an easing in the flow in cases where the sources are above 50 MPc of Tierra.Sin embargo has not reached any conclusions pilot on the existence of this court (called cutting GZK) due to the limited statistics available real data, to be involved low flows primary. At these energies so high the Cosmic Ray are detected through cascades produced in a natural environment-in this case the atmósfera.Partiendo an initial interaction with an atom in the atmosphere to produce secondary particles follows a multiplicative process until the energy share were desvanece.El Observatory Pierre Auger giant combines an array of detectors at ground level that detects particles secondary waterfalls, with 4 telescopes that collect the fluorescence light emitted during development. One of the most important features to rebuild a waterfall is its angle of incidence, which in the matrix of detectors is based on the arrival times of particles secundarias.Entre these highlights muones, which have a great capacity penetration and also interact without traveling almost from its point of production. This thesis has been modeled analytically component muónica of cascadas.Se has placed special emphasis on the distribution of arrival times, which has allowed them to understand the mechanisms that cause the delay of muones, and the form of distributions . Once this model seha applied to a series of case studies: it has been determined the angular resolution of an array of detectors (the Pierre Auger Observatory South) and proposed methods of reconstruction based on modelo.También has been described a method to reconstruct the distribution of the distance of production of muones, which can be used to increase the aceptancia neutrino cascades in horizontal.

Author: PIEDRA GOMEZ JONATAN.
Year: 2004.
University: CANTABRIA.
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: One of the ways that exist to etudiar the validity of the Standard Model of Particle Physics is the detemrinación requires the CKM matrix. To this end there are a number of experimental measures, including the frequency of oscillation inn Bs, which only knows its lower limit, 14.5 picosegundo-1. This thesis has been used a brightness of 355 picobarn-1 as part of the complex process to improve the limit. This uses the method of amplitude, which requires knowledge of the weakening of labelers flavor for each event. Such dilution is parameterized in a large sample inclusive obtained from the trigger of leptón and trace displaced. Differences between this cinematic sample and the sample signal Bs dictate the need to obtain an absolute calibration of the dilution in samples similar to the signal. In this thesis uses four samples completely rebuilt to make the absolute calibration of dilution: B +-higher than Jpsi K + and Bd0-higher than Jpsi K * 0, which came from the trigger of muones; and B +-higher than D0bar pi + and Bd0-greater than D-pi +, which come from the trigger of two traces displaced. Once seleccioinadas these samples are measured half-lives of inns B in the four channels of disintegration; for this maximizes a likelihood whose value is different for each event. The likelihood depends on three variables that define the event: invariant mass rebuilt, length of disintegration and error to the extent that length of disintegration. Also at the likelihood describes ways that are expected to signal events and happenings of substance distributions invariant mass and length of disintegration. The adjustments for the break with Jpsi in the final state are easy compared to the other two channels disintegration. They distribution of decay length is biased because the trigger trace displaced selected on the basis of maximum and minimum values for parameter impact, among other cuts. This bias in the length of decay corrected with an efficiency curve determined using samples from Monte Carlo that describe the signal. The half-lives are aware obtained in the PDG. The likelihood is compounded when introducing dilution event to event and the decision of labelers flavor, which combines an exclusive, ie if the best minor dilution efficiency * * greater dilution that fails we look to the second better, and so secesivamente. At this point are measured five factors of scale, one for each etiquetador flavor. Besides determining the frequency of oscillation of the inns Bd, whose value is known, finding the desired result. On average, scaling factors taken a value of 0.9, compatible with the unity within the errors measured. These 5 scale factors, together with the dilution parametrized, are used in the method of amplitude in the decay Bs0-higher than Ds- pi + and Bs0-higher than lnuDs-X improving the outcome of Run Ie increasing sensitivity world 18.2 to 18.5 picosegundo-1.

Author: CALDERON TAZON ALICIA.
Year: 2005.
University: CANTABRIA.
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: The work described is part of the detector Particle Physics CMS (Compact Muon Solenoid), which will operate one of the points of interaction accelerator hadrónico LHC (Large Hadron Collider) at CERN. The research focuses on the construction, calibration and evaluation of an optical system alignment, Link system for the absolute referencing between different subdetectores Trace (CMS detector traces and the central spectrometer mounes). The objective of this system is monitored on a continuous position in the space of these subdetectores pressures micrométricas to ensure optimum selection / reconstruction and measure the time of the muones produced in collisions protón-protón. It presents the simulation of various scenarios desalineamiento (realistic simulation of the expected movements in the trace detectors), which will take place in the CMS detector and the study of its impact on the benefits of reconstruction Online System (Trigger) and off line muones simple. It describes the process of selection and characterization of the components responsible for generating lines optical reference System Link: laser diodes, optical systems colimación and singlemode fiber optics. In the particular case of singlemode fiber optics presents a study on the effect of radiation (gamma rays and neutrons) in the optical attenuation in the visible region. It also details the process of adjustment and calibration end of the geometry of the lines of reference System Link, generated in two large mechanical structures: Alignment Ring and Link Disc

Author: JOSE ENRIQUE PALENCIA CORTEZON.
Year: 2006.
University: CANTABRIA.
Place of defense: FACULTAD DE CIENCIAS.
Place of preparation: FACULTAD DE CIENCIAS.

Summary: This paper presents the algorithm Jet Probability as a fundamental tool in the selection of events in the experiment CDF (Collider Detector at fermilab. Are discussed in depth the performance of this algorithm and shows it into effect in the analysis of the measure the cross section of producing pairs top-antitop in collisions protón-antiprotón a center of mass energy of 1.96 TeV and with a sample of data from 318 pb inverse, where events are selected with final statements which contain a leptón isolated high time transverse high transverse energy loss and at least three jets, one of which must be labeled jet b. has studied the consistency of the results obtained by applying several methods, and it is found that the cross section obtained is consistent with other results and also with the theoretical prediction.