Hyperon production in proton-nucleus collisions at a center-of-mass energy of sqrt(S_NN)=41.6 GeV at HERA-B and design of silicon microstrip detectors for tracking at LHCb

Themen dieser Arbeit sind Messungen von Hyperonenproduktion in Proton-Kern-Wechselwirkungen bei 41.6 GeV Schwerpunktsenergie mit dem Hera-B-Detektor am DESY, Hamburg, und das Design von Siliziumstreifensensoren für das LHCb-Experiment am CERN, Genf (Schweiz). Lambda-, Xi- und Omega-Hyperonen und ihre Antiteilchen wurden in 113.5*10^6 inelastischen Wechselwirkungen von Protonen mit festen Kohlenstoff-, Titan- und Wolfram-Targets rekonstruiert. Mithilfe dieser Datensätze konnten Antiteilchen-zu-Teilchen-Verhältnisse, Wirkungsquerschnitte sowohl über den kinematischen Messbereich von Hera-B integriert als auch differenziell als Funktion des Transversalimpulses, $d\sigma/dp_T^2$ (für Lambda und Xi), und der Rapidität, $d\sigma/dy$ (nur für Lambda), gemessen werden, sowie die Abhängigkeit dieser Messgrößen von der Massenzahl des Targetkerns, parametrisiert nach dem Glauber-Modell. Die gemessenen Verhältnisse folgen dem gleichen Trend wie die Energieabhängigkeit der entsprechenden Messungen in Kern-Kern-Wechsel-wirkungen. Silizumstreifensensoren wurden für das Spurrekonstruktionssystem des LHCb-Detektors entwickelt. Unter Zuhilfenahme von am CERN durchgeführten Strahltests wurde der Einfluss der Streifengeometrie und der Substratdicke auf die Eigenschaften des Sensors ermittelt, um das Optimum unter den gegensätzlichen Erfordernissen eines hohen Signal-zu-Rauschen-Verhältnisses, einer kleinen Anzahl an Auslesekanälen und einer niedrigen Spurbelegungsdichte zu erzielen. Der Detektor befindet sich momentan in der Bauphase, der Beginn des Messbetriebs ist für Herbst 2007 geplant.The topics of this thesis are the measurements of hyperon production in proton-nucleus collisions at a center-of-mass energy of 41.6 GeV with the Hera-B detector located at DESY, Hamburg (Germany), and the design of silicon microstrip sensors for the LHCb experiment at CERN, Geneva (Switzerland). Lambda, Xi and Omega hyperons and their antiparticles were reconstructed from 113.5*10^6 inelastic collisions of protons with fixed carbon, titanium and tungsten targets. With these samples, antiparticle-to-particle ratios, cross sections integrated for the accessible kinematic region of Hera-B and single differential cross sections as function of transverse momentum, $d\sigma/dp_T^2$ (for Lambda and Xi) and rapidity, $d\sigma/dy$ (for Lambda only), have been been measured as well as the dependence of these quantities on the atomic number of the target nucleus, as parameterized using the Glauber model. The obtained ratios follow the same trend as found for the energy dependence of measurements from nucleus-nucleus collisions. Silicon microstrip sensors have been designed for the tracking system of the LHCb detector. Evaluating the performance in beam tests at CERN, the strip geometry and sensor thickness were varied optimizing for a large signal-to-noise ratio, a small number of read-out channels and a low occupancy. The detector is currently being built to be operational for first proton-proton collisions in autumn 2007

Design of the LHCb silicon tracker

The LHCb silicon tracker is a large-surface silicon micro-strip detector that will cover an important part of the LHCb tracking system. Its data will be used in the trigger to select high-$p_T$ daughter particles from B-meson decays, and in the offline analysis to reconstruct trajectories of charged particles in the very forward region of the detector. Readout strips of up to 38 cm in length with strip pitches of approximately 200 $\mu$m will be employed. For the readout, a custom developed front-end chip and a Gbit digital optical link will be used. The design of detector, silicon sensors and readout link is presented

Unraveling the Nanoscale Morphologies of Mesoporous Perovskite Solar Cells and Their Correlation to Device Performance

Hybrid solar cells based on organometal halide perovskite absorbers have recently emerged as promising class for cost- and energy-efficient photovoltaics. So far, unraveling the morphology of the different materials within the nanostructured absorber layer has not been accomplished. Here, we present the first visualization of the mesoporous absorber layer in a perovskite solar cell from analytical transmission electron microscopy studies. Material contrast is achieved by electron spectroscopic imaging. We found that infiltration of the hole transport material into the scaffold is low and inhomogeneous. Furthermore, our data suggest that the device performance is strongly affected by the morphology of the TiO₂ scaffold with a fine grained structure being disadvantageous

The LHCb silicon tracker

The Silicon Tracker is a large-surface silicon micro-strip detector that covers the full acceptance of the experiment in a single tracking station upstream of the spectrometer magnet and the inner-most part of three tracking stations downstream of the magnet. Special emphasis has been put on module quality assurance at all stages of the production. Various tests are performed after each production step and each module goes through several burn-in cycles. The design of the LHCb silicon detectors is described and the main lessons learnt from the R&D phase are summarised. Focus will be on the experience from module production and the quality assurance program

The LHCb Silicon Tracker

LHCb is one of the experiments for the Large Hadron Collider at CERN, dedicated to B-physics and CP-violation measurements. To fully exploit the physics potential, a good tracking performance with high effciency in a high particle density environment close to the beam pipe is required. Silicon strip detectors with large readout pitch and long strips will be used for the LHCb Silicon Tracker. The design and test beam results are presented here

The LHCb Silicon Tracker

LHCb is one of the experiments for the Large Hadron Collider at CERN, dedicated to B-physics and CP-violation measurements. To fully exploit the physics potential, a good tracking performance with high effciency in a high particle density environment close to the beam pipe is required. Silicon strip detectors with large readout pitch and long strips will be used for the LHCb Inner Tracker after the magnet and the Trigger Tracker station in front of the magnet. The design of the Silicon Tracker in LHCb and corresponding test beam results are presented here

The LHCb Silicon Tracker

Wide pitch silicon micro-strip detectors will be used in both the LHCb Inner Tracker and the Trigger Tracker. In total an area of 12 m$^2$ will covered with silicon using ladders of up to 33 cm in length. The design of both detectors and corresponding test beam results are presented

Production of the LHCb Silicon Tracker Readout Electronics

We give an overview on the status of production of the LHCb Silicon Tracker Electronics. Lessons learned together with industry in the preseries production of the Silicon Tracker Digitizer Boards were integrated into the design to optimize the production and assembly yield for the main batch of 700 Digitizer Boards. A report on the preseries readout module performance and on the testing procedures for the full production lot is given. In addition, a final proton irradiation test of a complete readout system has been performed, of which results will be presented