PARTICLE DETECTORS

Author: AGUILÓ CHIVITE ERNEST.
Year: 2004.
University: BARCELONA [www.ub.es].
Place of defense: FACULTAD DE FÍSICA.
Place of preparation: FACULTAD DE FÍSICA UNIVERSIDAD DE BARCELONA.

Summary: The thesis has been developed in the group of Barcelona's future experiment LHCB, which is cago, among other tereas, dela electronic subdetectal SPD.Este is a flat cell centelleador allowing distinguish between electrons and photons in the first level of trigger. In this thesis has simulated how temporary signal SPD, which is wider, 25ms (the period of integration of electronics LHCB), as it affects the following periods 25ms.La simulation has been adjusted experimental data with greater cósmicos.Una time understanding its signal SPD has been used to trigger the improvement of electrons and fotones.La improvement has been a 10% and a 20% respectively. finally have improved measures, as well as the determination of their mistakes in the reconstruction of the canal bd-j / 4 (e + e) Ks, the channel used for improving the trigger of electrons through the recovery dela energy irreconstruible radiated by the pair e + e with an adjustment its vertex forced the mass of j / 4 and changing covariance matrices of the moments of the pair.

Author: KNASTER REFOLIO JUAN RAMÓN.
Year: 2004.
University: POLITÉCNICA DE MADRID [www.upm.es].
Place of defense: E.T.S. INGENIEROS INDUSTRIALES.
Place of preparation: E.T.S. INGENIEROS INDUSTRIALES.

Summary: The colisionador of protenes currently under construction at CERN named LHC (Large Hadron Collider) will become the most powerful accelerator ever built with an energy of 7 TeV proton. It is expected that this operation in 2007. Consisting of 4 major experiments one, LHCb, will be devoted to the investigation of CP violation. The demands of the vacuum chamber experiments in colisionadores particles are very special. This doctoral thesis, in a first part, makes a historical analysis of the evolution in design since the birth of the colisionadores early in the 70 describing these criteria in detail. In a second part describes the implementation of these principles in the design of the vacuum chamber experiment LCHb, explaining the developments made. The vacuum chamber to be established is a way biconica (25 and 10 mrad) from 12 m beryllium from 1 to 2.4mm thick, consist of compensating metallic aluminum flanges ultra-alto empty aluminum specifically designed and a window spherical of 850 mm diameter manufactured in aluminum. The background radiation generated by this design is reduced by a factor of 5 over the vacuum chamber originally considered.

Author: LLosá Llácer Gabriela.
Year: 2005.
University: VALENCIA [www.uv.es].
Place of defense: Facultad de Física, Universitat de València.
Place of preparation: Faculatad de Física, Universitat de València.

Summary: The level of development reached by silicon detectors on the occasion of its application in high-energy experiments over the past 30 years makes it possible application to other disciplines, such as medical physics. The use of silicon detectors in this field enables the development of a technique known as Compton method of image formation, in which the mechanics used in SPECT collimators are replaced by silicon detectors. Photons suffer Compton scattering in silicon (scattering detector), and are subsequently absorbed in a centelleador. This avoids the inverse relationship between resolution and efficiency associated with mechanical collimators, and enabling improved both. Of particular interest is the application of this technique to build a probe prostate. Prostate cancer is one of the most common among males. However, the techniques commonly used for the detection of tumors, which give excellent results in other cancers, are not suitable for this type of cancer. A probe Compton would improve by a factor of 5 spatial resolution of the methods used at present, and efficiency in a fctor 40 according to the simulations carried out. It has carried out the construction of a first prototype of a probe prostate. The scattering detector consists of five modules of silicon, equipped with sensors 1 mm thick. As absorption detector has been used three modules centelleadores of Nal (IT) situaddos on both sides and underneath. Data analysis and reconstruction of the images allows for the resolution of the prototype. It has been verified improvements in the resolution to scatter low angles, the greater distance sector dispersion of the absorption, and higher energy photon incident. It has obtained a spatial resolution of 5mm FWHM for the 356 keV photons emitted at a distance of 12 cm from the scattering detector, which exceeds that of the methods used at present. Simulations predict a vast improvement in resolution when the source is located near the scattering detector.

Author: Fernández Tomás María Magdalena.
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: It has been developed and optimized clinically evaluated a mini portable gamma camera. Although we have focused on the field of diagnostic nuclear medicine from studies of small bodies, it finds applications in other fields such as industry or radiofarmacia. The device has a size, weight and reduced field of vision. The main advantages with respect to other mini gamma cameras are in the electronics are completely integrated into the camera body and that the channel of communication with the computer and food are carried out through USB port. All these features make it completely portable. With all this, the parameters that describe their behavior important for the proper functioning of the device are comparable clinical or have been enhanced over those of other gamma cameras. The paper shows:-the design of the device and the same justification, which it is noteworthy that is based on a PSPMT, a crystal centelleador and continuous and pinhole collimators kind of different openings - development and automation of the method of calibration and validation of this from several cameras similar characteristics-characterization system from adapting protocols acceptance (European Standard UNE-EN 60789) and control equipment (Royal Decree RD 1841/1997) established Nuclear Medicine. - Studies of additional characterization in terms of sensitivity, resolution and extrinsic diameter collimator troops or uniformity - clinical validation of the camera from measures with patients, its design and its software.

Author: Lerche Christoph Werner.
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: It has developed an innovative method for measuring the depth of interaction rayos-gamma in scintillation crystals thick and continuous. The new technique is using this parameter in estimating the width of the distribution of light in scintillation crystals which is detected by a fotomultiplicador. For its quick and easy measure was designed revises very low cost of conventional circuits division of cargo to be used with great frequency for determining the position of impact on detectors rayos-gamma for Nuclear Medicine. Measures were presented with a real detector, based on a crystal LSO size 42mm X 42mm X 10mm, and a fotomultiplicador H8500 Hamamatsu Photonics. The response of the detector consists of three stages no-triviales and timing trivial. The timing trivial normally represents the energy of impact and moments no-triviales are centroids and the second time. Experiments show that the centroids are not affected by the extent of extra time. The medium resolution at the moment is less than 5%. In the experiments there was a resolution energy averaged 25% with the minimum value at the heart of 17% and the maximum value in a corner of 70%. An algorithm is presented for the reconstruction of the position of real impact from the stage. For this purpose was used an analytical model of the distribution of signal, which was verified experimentally. For the three currently not trivial noted that the predictions of the model reproduced very well the actions of the moment. The deviations were always below 11%, except for the time being trivial. In the latter case, the deviations were always below 25%. We used the model to predict the behavior of the detector at 40000 different positions of impact. The results for the two centroids and the second time was interpolaron with orders 12 for components and order 5 for the normal component. We used the inverse of Moore-Penrose in conjunction with the 40000 positions impact to obtain an array detector that allows reconstruction of the impact position of times measured with the load circuit division improved. The spatial resolution of the detector was in this case of 1.9 mm for the two transverse dimensions and 3.9 mm for the depth of interaction. This presents a substantial improvement on the resolution of the detector obtained using moments (3.4 mm and 4.9 mm) for the same coordinates. Especially outcome for the resolution in depth is very important, because there are very few methods to reach this resolution. However, failure to fully correct the no-linealidad's position with this method. With the values mentioned here that yielded a no-linealidad residual approximately 10%. The three-dimensional spatial resolution and you get so far with the method presented was insufficient to rebuild the actual energy from the moment with trivial information nonlinear moments.

Author: BEDOGNI ROBERTO.
Year: 2005.
University: AUTÓNOMA DE BARCELONA [www.uab.es].
Place of defense: UNIVERSIDAD AUTONOMA DE BARCELONA.
Place of preparation: UNIVERSIDAD AUTÓNOMA DE BARCELOAN Y INFN - FRASCATI (ITALIA).