1,212 research outputs found
Bestimmung der Protonstrukturfunktion bei großen Impulsüberträgen am H1-Experiment bei HERA
No full textIn this thesis a determination of the proton structure function at large momentum transfers in the kinematical domain and is presented. The data for this analysis was taken by the HERA experiment H1 in 1994 and corresponds to an integrated luminosity . The events are characterized by an electron, which was scattered at a large angle by a constituent quark of the proton. The selection of the events was mainly based on the detection of the scattered electron in the H1 calorimeter. Two different procedures were used for reconstruction of the kinematical variables and . The Electron Method is based on the energy and the angle of the scattered electron, while the -Method in addition uses information of the final hadronic state. The main topics of this thesis were the reconstruction of the energy and the angle of the scattered electron, the efficiency of the selection and the determination of the remaining background in the selected data. The influence of the weak interaction was investigated. Both reconstruction methods gave results for which are in good agreement within the errors. A section of the results together with other H1 results in the kinematical domain of low momentum transfers were taken for a NLO-QCD-Fit, which was based on the DGLAP equations. This NLO-QCD-Fit, which described the data well within the errors, was recently published by the H1 Collaboration
HERA-B, an experiment to study CP violation at the HERA proton ring using an internal target
No full textThis paper discusses a dedicated fixed target experiment at the HERA proton ring with the goal to observe CP violation in the B → J ψK s 0 decay channel, using a detector with a highly selective trigger for lepton pairs from the J ψ decay. The precision of the asymmetry, sin 2β, is expected to reach 0.13 within one year of running
Event classification with the electronic detectors of the OPERA experiment using neural networks
No full textThe OPERA experiment searches for ↔ oscillations in appearance mode. It uses the emulsion cloud chamber (ECC) technique for a high spatial resolution combined with on-line components for event localisation and muon identification.The analysis of events in an ECC detector takes considerable time, especially in case of ↔ candidate events. A ranking of events by a probability for being a ↔ event can speed up the analysis of the OPERA experiment. An algorithm for such an event ranking based on a classification-type neural network is presented in this thesis. Almost all candidate events can be found within the first 30% of the analysed events if the described ranking is applied. This event ranking is currently applied for testing purposes by the OPERA collaboration, a decision on a full application for the whole analysis is pending.A similar neural network is used for discrimination between neutral and charged current events. This is used to observe neutrino oscillations in disappearance mode with the on-line components of the OPERA detector by measuring the energy dependence of the fraction of neutral current interactions. The confidence level of the observed oscillation effect is 87%. Assuming full mixing, the mass splittinghas been determined to |∆m | = eV
Photoproduction at HERA detecting a scattered proton with the H1 forward proton spectrometer
No full textIn this thesis the measurement of the differential semi-inclusive cross section in Photoproduction with a leading proton is presented. The data were taken 1995 using the H1 detector at the HERA storage ring, the corresponding integrated Luminosity is = . Protons were measured in the energy range of = = $90, 187 and 231 GeV$. The detection of leading protons with the H1 Forward Proton Spectometer (FPS) was possible for the first time in 1995. The FPS consists of two detector stations at 81 and 90 m and the proton magnets located between these stations and the interaction vertex. Using the measured proton track and the known beam optics, the proton energy $E_{p\prime}$ and the scattering angle $\vartheta_p \prime$, at vertex position are reconstructed. The resolution is $\Delta E_p \prime$ = $2 - 6 GeV, \Delta \vartheta_x$ = $5 - 10 \mu rad$ and $\Delta \vartheta_y$ = $5 - 100 \mu rad$ depending on the other quantities at a time. These values meet the design requirements.The selection efficiency and acceptance as well as corrections used for the cross section measurement are calculated. The differential cross section is of the order of $7 nb/GeV$ and does within errors not depend on $E_p \prime$ and . A Regge fit shows the data to be compatible with exchange. To get information about the contribution from hard Photoproduction 2-jet events have been selected using a cone algorithm. The 2-jet cross section is of the order of . A comparison with predictions of the POMPYT model shows that the jet data can be described by Pion and Pomeron exchange within the Regge picture
A measurement of trilinear gauge couplings using the DELPHI detector
No full textA measurement of the Trilinear Gauge Boson Couplings is performed on the 53.0 pb"-"1 of data collected by the DELPHI experiment in e"+e"- collisions at a centre-of-mass energy of 183 GeV. The differential cross-sections of W pair events from the qq-barl#nu# final state are analysed to determine the couplings #DELTA#g_1"z, #lambda#_#gamma# and #DELTA##kappa#_#gamma# associated with the WWZ/WW#gamma# vertex. The couplings describe the magnetic dipole moment and electric quadrupole moment of the W boson. The results are transformed in a measurement of the gyromagnetic ratio, expressed as g - 2 of the W. The measured coupling values, magnetic moment and electric moment as well as the g - 2 value agree with the Standard Model predictions. (author)Available from British Library Document Supply Centre-DSC:DXN045606 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo
Application of liquid-core fibres for a radiation-hard vertex detector
No full textWe propose a novel vertex detector based on liquid-core fibers which can reach and exceed the performance of the current HERA-B vertex detector, while offering even greater resistance to aging due to radiation effects. This radiation resistance would provide an improved vertex resolution by allowing one to place the detector elements closer to the particle beam, and thus provide an improvement in the measurement of Bs, mixing while extending the accessible region of xs
Die Entdeckung der b u-Quark-Übergänge: Einer der letzten unbekannten Parameter des Standardmodells der Elementarteilchen ist jetzt bestimmt
No full textHERA-B, an experiment to study CP violation at the HERA proton ring using an internal target
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