http://hdl.handle.net/1956/914 Search the Channel search http://bora.uib.no/simple-search http://hdl.handle.net/1956/2373 Title: Charged Higgs boson searches and SemiConductor Tracker commissioning for the ATLAS experiment <br/> <br/>Authors: Mohn, Bjarte Alsaker <br/> <br/>Abstract: The ATLAS (A Toroidal Lhc ApparatuS) experiment is one of four major experiments presently being installed at the upcoming Large Hadron Collider (LHC) at the European Centre for Nuclear Research (CERN) outside Geneva. In this thesis we present work done on both the simulation of the ATLAS physics potential for a charged Higgs boson and the construction of the Semiconductor Tracker (SCT) - a subdetector within the ATLAS Inner Detector. The discovery of a charged Higgs boson would be an unambiguous sign of physics beyond the Standard Model (SM) and it is thus of great interest to study the ATLAS potential for a charged Higgs discovery. Two such studies have been conducted for this thesis. In the first study a large-mass-splitting Minimal Supersymmetric Standard Model (MSSM) is assumed in which the charged Higgs boson decays into a W boson and a neutral Higgs may receive a large branching ratio.We conclude, however, that charged Higgs searches in this decay channel are made difficult by a large irreducible SM background. Despite its small brancing ratio at high masses for the charged Higgs boson, the decay mode H± →τν remains the most powerful decay mode for a charged Higgs discovery. Discovery through this channel depends heavily on excellent detector performance and understanding of the background.We show that with detector full simulation and with more complete background samples this channel still remains the most powerful decay mode. We also show that it is possible to connect the discovery countour for charged Higgs boson masses below and above the top-quark mass. The SCT detector is a tracking detector based on silicon microstrip detector technology. It is a highly modular detector consisting of 4088 detector modules that are mounted on 4 barrels and 9x2 end cap disks. Some 320 of the SCT barrel detector modules were built by a Scandinavian collaboration and presented here are the results of this work and procedures for building and quality assurance. Each SCT detector module is powered by an individual high and low voltage supply and thus a large scale and robust power supply control system is needed for controlling the SCT detector. Presented in this thesis is work done to prepare the SCT power supply software for this task, as well as the results obtained during testing and development. As a part of the commissioning of the completed SCT barrel, a series of cosmic runs were performed. Data from these runs allowed for first studies of the detector alignment and alignment results and conlusions thereof are presented in this thesis. Wed, 20 Jun 2007 22:58:59 GMT http://hdl.handle.net/1956/2322 Title: Læring av naturfag og matematikk gjennom prosjekter i teknologi og design <br/> <br/>Authors: Kolstø, Stein Dankert <br/> <br/>Description: Denne artikkelen er en noe omarbeidet versjon av en artikkel i Tangenten nr.4, 2006, ss. 13-15: Kolstø, S. D.: Læring av matematikk gjennom prosjekter i teknologi og design. Se også: http://hdl.handle.net/1956/2227 Sat, 29 Oct 2005 22:58:59 GMT http://hdl.handle.net/1956/2301 Title: Supersymmetric Cascade Decays at the LHC <br/> <br/>Authors: Raklev, Are R. Sun, 03 Jun 2007 22:58:59 GMT http://hdl.handle.net/1956/2227 Title: Læring av matematikk gjennom prosjekter i teknologi og design <br/> <br/>Authors: Kolstø, Stein Dankert Sat, 29 Oct 2005 22:58:59 GMT http://hdl.handle.net/1956/2225 Title: Et allmenndannende naturfag : fagets betydning for demokratisk deltagelse <br/> <br/>Authors: Kolstø, Stein Dankert <br/> <br/>Description: Tidligere utgitt i: Naturfagdidaktikk : perspektiver, forskning, utvikling / Doris Jorde og Berit Bungum (red.). - Oslo : Gyldendal akademisk, 2003. Sat, 29 Oct 2005 22:58:59 GMT http://hdl.handle.net/1956/2215 Title: Marine seismics with a pulsed combustion source and Pseudo Noise codes <br/> <br/>Authors: Askeland, Bjørn; Hobæk, Halvor; Mjelde, Rolf <br/> <br/>Abstract: There has been an ongoing debate for years of how dangerous seismic surveys are with respect to marine life. Marine seismics is today dominated by airgun technology, where high energy is generated by a release of compressed air into the water. The objective of the “Time coded impulse seismic technique” project is to examine whether a new low energy acoustic source can be used for seismic purposes. If the method turns out to be successful, the low output energy and continuous operation will make the source suitable in environmental sensitive areas. The Low level Acoustic Combustion Source (LACS) is a petrol driven pulsed underwater acoustic source. It operates at a few meters depth, and each shot can be digitally controlled from the surface by a computer located in the mother vessel. A presentation of the recorded LACS signal characteristics, the modulation, the Pseudo Noise coding/decoding principles and field test results, is given. The importance of using an optimized code with fine resolution and the near field recording as correlator sequence was demonstrated. Clear correlation peaks could then be seen from the bottom and sub bottom reflectors. Mon, 26 Feb 2007 22:58:59 GMT http://hdl.handle.net/1956/2162 Title: Search for the rare decay B → πℓ+ℓ− in the BABAR experiment <br/> <br/>Authors: Ofte, Ingrid <br/> <br/>Abstract: Some characters in this abstract are not rendered correctly, please consult the PDF-version.; The rare decay B → πℓ+ℓ− is the simplest manifestation of a b → dℓ+ℓ− flavor-changing neutral current (FCNC) process. This type of process only proceeds through penguin loop or box diagrams and is sensitive to physics at the electroweak scale. It can be used to constrain parameters of the Standard Model and its extensions. B → πℓ+ℓ− events have not yet been observed; the branching fraction is expected to be an order of magnitude smaller than the measured branching fraction for the similar B → Kℓ+ℓ− decay.; Using 230 million BB meson pairs collected with the BABAR detector, we have done a search for the rare decay B → πℓ+ℓ−. The data was produced in e+e− collision at the Υ(4S) resonance in the PEP-II collider between 1999 and 2004. Four exclusive B-meson decay modes have been reconstructed: B+ → π+ℓ+ℓ− and B0 → π0ℓ+ℓ−, where ℓ+ℓ− is either an electron pair (e+e−) or a muon pair (μ+μ−). We find no evidence for a signal, and we obtain upper limits on the branching fractions B. Assuming the isospin relation B(B+ → π+ℓ+ℓ−) = 2 × τB+ τB0 B(B0 →π0ℓ+ℓ−), we obtain an upper limit at 90% confidence level on the the lepton-flavor–averaged branching fraction of B → πℓ+ℓ− to be B(B → πℓ+ℓ−) < 9.5 × 10−8 at 90% C.L.; We have also reconstructed two control modes B+ → π+e±μ╒ and B0 → π0e±μ╒, and we also obtain an upper limit at 90%confidence level on the lepton-flavor–violating decay B → πeμ of B(B → πeμ) < 9.2 × 10−8 at 90% C.L. This is the first search for these rare decays at the current B-Factory experiments. This limit is an improvement by four orders of magnitude with respect to the the previous experimental limit, and about a factor three above Standard Model predictions. Mon, 11 Dec 2006 22:58:59 GMT http://hdl.handle.net/1956/2161 Title: A seismic field test with a Low level Acoustic Combustion Source and Pseudo Noise codes <br/> <br/>Authors: Askeland, Bjørn; Ruud, Bent; Hobæk, Halvor; Mjelde, Rolf <br/> <br/>Abstract: The Low level Acoustic Combustion Source (LACS) is a new type of pulsed underwater acoustic source with an output level of 0.5-1.0 barm peak to peak. The source is based on a combustion engine and intended for shallow seismic surveys. It operates at 5 m depth and is able to fire pulses at a rate of up to 11 shots per second. Because of the source’s low output level, it is expected to be more suitable than other sources in environmental sensitive areas. The low pulse level may be compensated for by an integration of energy from a sequence of pulses. This article describes the results of a seismic field test in Byfjorden outside Bergen, Norway. The best seismic result is achieved using deconvolution or an iterative correlation method where the correlator sequence is recorded right below the seismic source. Compared with airgun results along the same survey path, the seismic picture based on the LACS source gives a clearer presentation of the bottom layers. Fri, 19 Jan 2007 22:58:59 GMT