EXPERIMENTAL PHYSICS OF HIGH-ENERGY

Author: FACAL SAN LUIS PEDRO.
Year: 2004.
University: SANTIAGO DE COMPOSTELA [www.usc.es].
Place of defense: FACULTADE DE FÍSICAS.
Place of preparation: FACULTAD DE FÍSICA.

Summary: The observation of cosmic rays with energies around 10 ** 20 eV has not yet been explained in a consistent manner. These energies are expected to cosmic rays interact with the cosmic microwave background radiation and lose energy. This effect limits the distance traveled by cosmic rays of high energy to about 50 Mpc and leads to a suppression expected in the flow of cosmic rays of the highest energies known as court GZK. The Pierre Auger Observatory has been designed for the study of cosmic rays of high energy and its aim is to obtain statistics events never reached high. Currently being built in Malargue, Argentina. Its main feature is that it combines for the first time the use of detectors and surface fluorescence detectors. This hybrid design is capable of providing a substantial improvement over the use of the two detection techniques separately. The work presented in this thesis contains original contributions in different aspects of the fluorescence detector Auger Observatory. The first two chapters are devoted to a brief introduction to the cosmic rays of high energy and Auger Observatory. The third chapter is devoted to system test developed for photomultiplier of the chamber of fluorescence detector and allowing their calibration and characterization. In the fourth chapter is devoted to the algorithm third trigger level of fluorescence detector, which enables the selection of candidate events by deleting events and the bottom line analysis of such candidates. The result of the geometric reconstruction of the events discussed is used to trigger the detector surface, and can expand the number of events hybrids. The fifth chapter deals with the reconstruction of the events of fluorescence detector including reconstruction of the geometry using hybrid data, treatment consisting of the fund because of the Cherenkov photons emitted during the development of the cascade and a model for the distribution of light in the focal area of the telescope. Finally, the sixth chapter is devoted to the analysis of events hybrids in 2004, studying the geometric resolution and major systematic uncertainty in the determination of energy.

Author: IGLESIAS ESCUDERO MARÍA DEL CARMEN.
Year: 2005.
University: VALENCIA [www.uv.es].
Place of defense: FACULTAD DE FÍSICA, UNIVERSITAT DE VALÈNCIA.
Place of preparation: FACULTAD DE FÍSICA, UNIVERSITAT DE VALÈNCIA.

Summary: I The LHC AND ATLAS LHC is a colisionador proton built at CERN. This machine will operate with a high brightness and cover ranges from GeV energies to cover the physics of the b quark, to the order of TeV, to try to explore new physics beyond the Standard Model. LHC consists of four detectors, among them, ATLAS has an overall purpose of studying physics offered LHC. ATLAS has been designed to have a good calorimetry emen far energy and identification of photons and electrons, supplemented by a calorimetry hadrónica to perform accurate measurements of the ET missing and jets through its complete coverage. In addition ATLAS will be able to measure with high precision the time of muones, as well as the trajectories of charged particles curved effect of the magnetic field of 2 T solenoid in the central region and the toroidal field outside. II. QUICK ALGORITMO ENERGY FLOW IN SIMULATION OF ATLAS (ATLFAST) Jets consist of jets of particles, mostly hadrones and some kaones. The information obtained on the jets will be used in many channels LHC physics. Besides studies QCD, the jets will be used in analysis of confirmation of SM (resonances of WyZ, or top, search SM Higgs ...), and physics studies beyond the SM as extra dimensions, SUSY .. . It is important to try to improve the resolution in the power of the jets. About 2 / 3 of energy jet from charged particles, however algorithms reconstruction jets do not use information from the routes, therefore it is interesting to use the algorithm Energy Flow. " This algorithm is to work together with input from the central and trace detector information from the energy deposited in the calorimeters, adding to the identification of particles. ATLFAST provides fast simulation of the detector response to the particles and its subsequent reconstruction. In ATLFAST no detailed simulation of the cascades in the calorimeters or signals traces left by the detector If only parameterized resolving energy calorimetry, and simulate the efficiency and resolution in PT Central detector. III. ALGORITMOS OF CLUSTERIZACIÓN Within software offline ATLAS (Athena), there are two types of algorithms clusterización: - Rebuilding deposition em A cone is made by focusing on the cell more ET and forms a window 3x5 or 3x7 cells. - For the cascades hadrónicas, the cells near the center with depositions ET above a certain threshold are added to the cluster: topological algorithm. The analysis has been used samples DC1 simulated with Geant3 of piones and very low energy neutrons. It seeks to understand how the cascade, the energy deposited in the cells and resolution in energy. First they have generated 1000 events:-Piones neutral: to understand the behavior of photons in the calorimeter MS-Piones loaded and neutrons: to better understand the cascade hadrónica with pT from 1 to 30 GeV and excluding electronic noise. After electronic noise was added to study its effect on the size of the waterfall and resolution. To compare the various algorithms clusterización was calculated ET in all cells of the calorimeter. The resolution obtained by the different algorithms will be compared with her. IV. TEST COMBINATION WITH HACES OF PARTICLES In 2004, a Combined Test beam of particles, "Combined Test Beam" (CTB), with parties of all subdetectores A 8 TLAS. Pa. 48d ra this analysis have been used data from the CBT at very low power (1-9 GeV) with information on both calorimeters and information traces. Samples of 100,000 events contain a mixture of electrons, piones and muones, it is necessary to implement cuts range for each type of particle. The objective of the analysis was to compare the various algorithms clusterización in CBT and the resolution of energy obtained.

Author: Domingo Santamaría Eva.
Year: 2005.
University: AUTÓNOMA DE BARCELONA [www.uab.es].
Place of defense: Institut de Física d'Altes Energies.
Place of preparation: Institut de Física d'Altes Energies.

Summary: Was the aim of this thesis to study the possibility that regions with important activity in star formation may appear as sources of gamma-rays for the current and near future gamma-ray detectors, both ground and space-satellite based. After a positive evaluation that the gamma-ray emission from galaxies prone of star formation processes (as starburst or ultra luminous infrared galaxies) may be close to the flux sensitivities of the current gamma-ray telescopes, a detailed model of the multiwavelength diffuse emission from the two best candidates, NGC 253 and Arp 220, has been presented. It is predicted that they will be detectable by GLAST, the next largest gamma-ray satellite, and by HESS and MAGIC, the current Cherenkov Telescopes, in case enough observation time is devoted. On the other hand, within this thesis it is described a model which proposes the emission of important fluxes of gamma-rays from regions of star formation within our Galaxy, as the stellar association of young OB stars. The model considers the emission of gamma-rays close to TeV energies by hadronic interactions within the stellar winds of some of the stars of the association, predicting at the same time that the emission at lower energies is substantially supressed due to the modulation effects that the incoming population of primary cosmic rays suffers when penetrating the winds. The best candidates among the galactic OB associations are briefly discussed. Finally, a first analysis of the data taken by the MAGIC Telescope when observing two of these regions of star formation is described. On one hand, the closest ultra luminous infrared galaxy, Arp 220. On the other, TeV J2032+4130, which is still an unidentified source whose origin has been several times related to the powerful stellar OB association Cygnus OB2. Any of both observations has implied a detection, and upper limits to the gamma-ray flux have been imposed. However, although the few hours of observation included in the present analysis, the MAGIC upper limits for TeV J2032+4130 are nearly at the level of the flux detected by the HEGRA experiment, so an analysis extended to the complete set of data available as well as deeper observations of this source with the MAGIC Telescope can provide promising results.

Author: Gaug Markus.
Year: 2005.
University: AUTÓNOMA DE BARCELONA [www.uab.es].
Place of defense: Inst.Fisica d'Altes Energies.
Place of preparation: Inst.Fisica d'Altes Energies.

Summary: The thesis consists of two parts: A technical one which describes the MAGIC Telescope and its calihration nd signal reconstruction and futher an analysis part describing the result of the first observation of the prompt emission of a Gamma Ray Burst., made by an IACT. After a general introduction to the IACT Technique, the MAGIC Telescope is presented. It is the largest existing single IACT in the world and built especially to reduce the energy theshold of observed gamma'rays from astrophysical sources. The photomultiplier camera , signal transmission and digitization chain are presented in this part. In the following, a thorough description of teh MAGIC calibration system is presented which was mainly built, ooperated and maintained by the author. The system consists of an assembly of ultra-fast and bright LEDs in three different colors which are used to send calibration light pulses of various intensities to the camera, which in turn gets characterized by its response to the series of light pulses. Two additional devices have been built to measure the absolute amount of light during one calibration pulse: Three obscured photomultipliers can extract signel photo'electron spectra and measure directly the Poissonian distribution of the number of incident photo-electrons, and a calibrated PIN diode yields an electrical signal proportional to the incident number of photons. A close look at the MAGIC signal extraction is given, new signal extractors are introduced, statistical parameters retrieved and the different extractors compared to each other. It was not possible to find an extractor optimizing all three requirements: robustness, discrimination power between signal and noise at low energies and a good time resolution, at the same time. However, a set of optimal extractors are proposed which meet at least two of the requirements well and give acceptable performance in the third case. Finally, the calibration system is used to derive characteristic parameters of the MAGIC camera: Correction factors to equalize the gain differences between channels, correction factors for the time delays and their evolution with time. The second part of the work starts with an introduction to the MAGIC standard analysis chain, with a new algorithm introduced in the image cleaning step. Then, a new unbiased method is presented to automatize the serach of the optimal cut value in the HADRONNESS parameter. Finally, the data of GRB050713a is analyzed which was followed up the MAGIC telescope only 40 seconds afte the onset of its prompt emission and while the prompt emission was still going on. MAGIC was following an alert by the Swift satellite. No signal could be seen neither during the prompt emission nor during the following 37 minutes of data taken until twilight, and upper limits on the high energy gamma flux above 150 GeV were derived. This result was published in ApJ in collaboration with other authors.

Author: Vázquez Doce Oton.
Year: 2006.
University: SANTIAGO DE COMPOSTELA [www.usc.es].
Place of defense: Facultad de Física..
Place of preparation: Facultad de Física USC.

Summary: Thesis framed in the DIRAC experiment to be carried out at CERN, in Geneva. This experiment seeks to learn with a precision of 10% the average life of the atom piónico, which would reveal a 5% accuracy the difference between the lengths of scattering pi-pi wave of isospin R S = 0 I = 2. The value of that difference | a0-a2 | has been predicted with small mistake on the theory chiral perturbativa. In the instrumental section, the author worked in the construction of two new detectors MSGC / GEM for the DIRAC experiment. It also introduced a system of tracing using these detectors, which gives a value of the average life of the atom piónico of 2.58 fs, with small errors, both statistical and systematic.

Author: Rodríguez Marrero Ana Yaiza.
Year: 2006.
University: AUTÓNOMA DE BARCELONA [www.uab.es].
Place of defense: IFAE.
Place of preparation: IFAE.

Summary: The discovery of neutrino oscillations is one of the most exciting recent developments in particle physics. Current and future neutrino experiments are aiming to make precise measurements of the oscillation parameters. Improving our understanding of neutrino-nucleus cross sections is crucial to these precision studies of neutrino oscillations. Ineractions in the neutrino energy region around 1 GeV are particulary important because this is the region of the expected oscillation signal in many experiments, but the cross sections in this region are not very well-known. This energy region is complicated due to overlapping contributinos from quasi-elastic scatting, resonant single pion production, and deep ineleastic scattering. The integrated energy and neutrino dependent corss section of the exclusice iteraction channel, nu_mu p -> mu p p+, and the inclusive interaction channel, nu_mu N -> mu N' p+, have been measured in neutrino-nucleus interaction in the carbon detector SciBar in the K2K experiment. The presented measurements contribute to the cross section measurements in the range about 1 GeV.