685 research outputs found
Evaluation of Compton scattering sequence reconstruction algorithms for a portable position sensitive radioactivity detector based on pixelated Cd(Zn)Te crystals
We present extensive simulation studies on the performance of algorithms for
the Compton sequence reconstruction used for the development of a portable
spectroscopic instrument (COCAE), with the capability to localize and identify
radioactive sources, by exploiting the Compton scattering imaging. Various
Compton Sequence reconstruction algorithms have been compared using a large
number of simulated events. These algorithms are based on Compton kinematics,
as well as on statistical test criteria that exploit the redundant information
of events having two or more photon interactions in the active detector's
volume. The efficiency of the best performing technique is estimated for a wide
range of incident gamma-ray photons emitted from point-like gamma sources.Comment: 16 pages, 17 figure
Little Higgs Model and Top-like Heavy Quark at CMS
The Little Higgs model gives an alternative solution to the fine-tuning problem present in the Standard Model (SM) of strong and electroweak interactions. The model invokes several new particles of TeV mass range, the lightest among them being a heavy quark (T) of charge +2/3. The CMS potential to discover this particle during intial years of LHC running is investigated
Study of Flavour Changing Neutral Currents in Top Quark Decays with the CMS Detector
This paper contains the first realistic estimate for the CMS sensitivity to Flavour Changing Neutral Currents (FCNC) in the top quark sector. The non Standard Model decays t -> Zq and t -> gamma q (q represents c or u quarks) have been studied at sqrts = 14 TeV exploiting leptonic decays of the Z boson and the photon. A realistic detector simulation has been adopted and the most relevant systematic effects have been addressed. The 5- sigma discovery limits for the two decays are BR(t-> qZ) =11.4 x 10^ -4 and BR(t -> gamma q ) =5.7 x 10^ -4, allowing some models of new physics to be tested
Simulated Performance Of Algorithms For The Localization Of Radioactive Sources From A Position Sensitive Radiation Detecting System (COCAE)
Simulation studies are presented regarding the performance of algorithms that
localize point-like radioactive sources detected by a position sensitive
portable radiation instrument (COCAE). The source direction is estimated by
using the List Mode Maximum Likelihood Expectation Maximization (LM-ML-EM)
imaging algorithm. Furthermore, the source-to-detector distance is evaluated by
three different algorithms based on the photo-peak count information of each
detecting layer, on the quality of the reconstructed source image as well as on
the triangulation method. These algorithms have been tested on a large number
of simulated photons in a wide energy range (from 200keV up to 2MeV) emitted by
point-like radioactive sources located at different orientation and
source-to-detector distances.Comment: 8 pages, 7 figures, 11th International Conference on Applications of
Nuclear Techniques, Crete, Greece, June 12-18, 201
Search for composite and exotic fermions at LEP 2
A search for unstable heavy fermions with the DELPHI detector at LEP is
reported. Sequential and non-canonical leptons, as well as excited leptons and
quarks, are considered. The data analysed correspond to an integrated
luminosity of about 48 pb^{-1} at an e^+e^- centre-of-mass energy of 183 GeV
and about 20 pb^{-1} equally shared between the centre-of-mass energies of 172
GeV and 161 GeV. The search for pair-produced new leptons establishes 95%
confidence level mass limits in the region between 70 GeV/c^2 and 90 GeV/c^2,
depending on the channel. The search for singly produced excited leptons and
quarks establishes upper limits on the ratio of the coupling of the excited
fermio
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