109 research outputs found
Properties of CsI(Tl) Crystals and their Optimization for Calorimetry of High Energy Photons
No full textA photomultiplier setup for precise relative CsI(Tl) crystal light yield and uniformity measurements is described. It is used for wrapping material studies to optimize the uniformity and the yield of the light output of 36 cm long crystals. The uniformity is an important property in high energy photon calorimetry. Results of an optimization of photodiode coupling to crystals, the influence of temperature and radiation damage to light and photoelectron yield are also presented. Work supported by BMBF under contract No. 06 DD 558 I y Corresponding author. E-mail: [email protected], Fax. +49 1 Introduction Although Thallium doped CsI crystals are widely used in high energy physics detectors [1, 2], new precision experiments at the B-meson factories presently under construction [3, 4] rely on CsI(Tl) calorimeters with improved energy resolution, electronic noise, and crystal radiation hardness. The energy resolution at low energies is influenced by the (temperature depen..
Properties of CsI(Tl) crystals and their optimization for calorimetry of high energy photons
No full textOptimized Laser Doped Back Surface Field for IBC Solar Cells
No full textAbstractWe present the optimization of the laser doped back surface field (BSF) for interdigitated back contact solar cells (IBC). The POCl3 flow limits the phosphorus concentration in the phosphorus silicate glass (PSG) during furnace diffusion, hence limits the sheet resistance when used as dopant source for laser doping. The saturation current densities of quasi steady state photo conductance (QSSPC) samples correlate with the sheet resistance dependent Auger contribution simulated with EDNA 2. Utilizing the measured saturation current density and contact resistance for various sheet resistances, we optimize the BSF doping for the recently presented 23.24% efficient laser processed IBC solar cell by numerical 3D solar cell simulation
The BaBar detector
No full textThis is the pre-print version of the Article. The official published version can be accessed from the link below. Copyright @ 2002 Elsevier.BABAR, the detector for the SLAC PEP-II asymmetric e+e− B Factory operating at the (4S) resonance, was designed to allow comprehensive studies of CP-violation in B-meson decays. Charged particle tracks are measured in a multi-layer silicon vertex tracker surrounded by a cylindrical wire drift chamber. Electromagnetic showers from electrons and photons are detected in an array of CsI crystals located just inside the solenoidal coil of a superconducting magnet. Muons and neutral hadrons are identified by arrays of resistive plate chambers inserted into gaps in the steel flux return of the magnet. Charged hadrons are identified by dE/dx measurements in the tracking detectors and in a ring-imaging Cherenkov detector surrounding the drift chamber. The trigger, data acquisition and data-monitoring systems , VME- and network-based, are controlled by custom-designed online software. Details of the layout and performance of the detector components and their associated electronics and software are presented.This work has been supported by the US Department of Energy and the National Science
Foundation, the Natural Sciences and Engineering Research Council (Canada), the Institute of High Energy Physics (P.R. China), le Commisariat a l’Energie Atomique and Institut National de Physique Nucl´eaire et de Physique des Particules (France), Bundesministerium fur Bildung und Forschung (Germany), Istituto Nazionale di Fisica Nucleare (Italy), the Research Council of
Norway, the Ministry of Science and Technology of the Russian Federation, and the Particle Physics and Astronomy Research Council (United Kingdom). In addition, individuals have received support from the Swiss National Foundation, the A.P. Sloan Foundation, the Research Corporation, and the Alexander von Humboldt Foundation
Conceptual design of an ALICE Tier-2 centre integrated into a multi-purpose computing facility
No full textThis thesis discusses the issues and challenges associated with the design and operation of a data analysis facility for a high-energy physics experiment at a multi-purpose computing centre. At the spotlight is a Tier-2 centre of the distributed computing model of the ALICE experiment at the Large Hadron Collider at CERN in Geneva, Switzerland. The design steps, examined in the thesis, include analysis and optimization of the I/O access patterns of the user workload, integration of the storage resources, and development of the techniques for effective system administration and operation of the facility in a shared computing environment. A number of I/O access performance issues on multiple levels of the I/O subsystem, introduced by utilization of hard disks for data storage, have been addressed by the means of exhaustive benchmarking and thorough analysis of the I/O of the user applications in the ALICE software framework. Defining the set of requirements to the storage system, describing the potential performance bottlenecks and single points of failure and examining possible ways to avoid them allows one to develop guidelines for selecting the way how to integrate the storage resources. The solution, how to preserve a specific software stack for the experiment in a shared environment, is presented along with its effects on the user workload performance. The proposal for a flexible model to deploy and operate the ALICE Tier-2 infrastructure and applications in a virtual environment through adoption of the cloud computing technology and the 'Infrastructure as Code' concept completes the thesis. Scientific software applications can be efficiently computed in a virtual environment, and there is an urgent need to adapt the infrastructure for effective usage of cloud resources
A measurement of the charged and neutral B meson lifetimes using fully reconstructed decays
No full textThe author first notes that Google, the trade mark, the project, the utilization - the "googling"- are social facts proven by the numbers – number of net surfers, of requests, of uses- and by the signs of adhesion - linguistics, economic, social. A socio linguistic analysis of the speeches of the persons in charge of Google and of users indicate that the social fact "googling" results in the emergence of a culture and a world community which shares it. They are supported by the language and also by the myths that were created and largely maintained by the owners the mark "Google Inc". The conclusion is that the current organization of the market of services on the Internet makes that Google Inc. is almost the only institution to know the population of the googlers. In order not to be subjected to this monopoly, however comfortable it is, the author proposes to develop a research program on the uses and users of Google
A measurement of the charged and neutral B meson lifetimes using fully reconstructed decays
No full textThe author first notes that Google, the trade mark, the project, the utilization - the "googling"- are social facts proven by the numbers – number of net surfers, of requests, of uses- and by the signs of adhesion - linguistics, economic, social. A socio linguistic analysis of the speeches of the persons in charge of Google and of users indicate that the social fact "googling" results in the emergence of a culture and a world community which shares it. They are supported by the language and also by the myths that were created and largely maintained by the owners the mark "Google Inc". The conclusion is that the current organization of the market of services on the Internet makes that Google Inc. is almost the only institution to know the population of the googlers. In order not to be subjected to this monopoly, however comfortable it is, the author proposes to develop a research program on the uses and users of Google
Design, construction and first operation of the large CsI calorimeter for the BaBar detector at the PEP-II storage rings
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