PPC's (parallel plate chambers) y su aplicación en calorimetría a bajo angulo en experimentos en el LHC

In the LHC working conditions especific detector requirements are fast response, high rate capability and radiation resistance. This is particularly important for detectors in the low angle regions such as the Very Forward Hadron Calorimeter ( VF ) of CMS , located at 11 m from the interaction point and covering the pseudorapidity region between 3 and 5. The major goals of this calorimeters are to improve the measured of the transverse energy ( Et) and the missing transverse energy ( Etmiss) ( important for Higgs searches, Top-quark physics, SUSY searches, etc) and the detection and reconstruction of forward jets characteristics of some importants process (such the TeV jets coming from the WW(ZZ) fusion Higgs production mechanism ). The requirements for this calorimeter are a moderate energy resolution and an adequate segmentation for forward jet tagging and reconstruction are needed. The purpose of this thesis is to show that calorimeters based on the Parallel Plate Chambers ( PPC. - Gaseous detector with planar electrodes working in avalanche mode) technology are feasible and adequate for very forward calorimetry in LHC experiments. We have construct diferent PPC cells and study its characteristics: time resolution; efficiency; radiation hardness; spark probability, etc. The tests show that this chambers are very fast (few ns, time resolution < 250 ps), radiation hard , sparking hard, have a high rate capability and a low spark probability and, using a apropiate gas mixture, a high efficiency . Therefore this chambers could be used for trigger and time of fly measurements in LHC experiments. We have construct several prototype calorimeters that was exposed to muon, electron and pion beams with energy range from 35 to 375 GeV. The prototypes was tested using different high voltages and two gases: pure CO2 and a mixture of CF4/CO2 (80/20). The collected charge was measured as a function of the high voltage and of the particle energy . We have also measured the energy resolution of this prototypes. A Monte-Carlo simulation, based on GEANT and our own simulation of the avalanche mode of operation, capable to reproduce the experimental data was developed, allowing to make predictions of the expected performance of a full size calorimeter. Using this Monte-Carlo model we have study the contribution of a low angle calorimetry, based on PPCs to the physics in CMS. We have study the physics performance expectations for the forward jets detection and reconstruction and for the Et and Etmiss reconstruction . We have also studied the effect of low energy neutrons coming from the pile-up background events in the CMS VF/PPC calorimeter. The effect over the calorimeter of the pile-up background events in terms of the irradiation and activation was calculated using our Monte-Carlo model. The test was made at SPS (at CERN ) test beam lines , ( H2 , H4 , X5 ), at ciclotron MGC-20 at ATOMKI (Debrece, Hungary), Serpukov and ITEP (Moscow. Russia) in the frame of the RD5 , RD37 and the CMS experiment.