124722292
Volume-based Representation of the Magnetic Field
The access to the magnetic field has a large impact on both CPU performance and accuracy of simulation, reconstruction and analysis software. An approach to the magnetic field access based on a volume geometry is described. The volumes are constructed in such a way that their boundaries correspond to field discontinuities, which are due to changes in magnetic permeability of the materials. The field in each volume is continuous. The value of the field at a given point of a volume is obtained by interpolation from a regular grid of values resulting from a TOSCA calculation or, when it is available, from a parameterization. To allow global access to the magnetic field, a volume finding algorithm that exploits explicitly the layout and the symmetries of the detector is used. The main clients of the magnetic field, which are the simulation (GEANT) and the propagation of track parameters and errors in the reconstruction, can be made aware of the magnetic field volumes by connecting the per-volume magnetic field providers to the corresponding volume in the respective geometries. In this way the global volume search is by-passed and the access to the field is sped up significantly.
118619470
Prospects for B Physics Measurements using the CMS Detector at the LHC
The LHC provides new opportunities to improve our understanding of the b quark using high statistics data samples and the 14 TeV center-of-mass energy. The prospects to measure the cross section for inclusive b production in events containing jets and at least one muon are presented. Additionally, the feasibility for CMS to measure the mass and the lifetime of the BBc meson and to search for the rare leptonic decay BsB →μμ are presented. Detailed studies of detector systematic effects and theoretical uncertainties are included Presented at XXXIII International Conference on High Energy Physics (ICHEP) July 26 August 2, 2006 Moscow
122362196
Accelerator constraints on dark matter
Abstract The relic density of supersymmetric dark matter is calculable in terms of supersymmetric and Standard Model parameters. The discovery of supersymmetric particles and determination of their parameters could well happen at the next generation hadron collider LHC presently under construction at CERN. The accelerator constraints on the SUSY parameter space at the LHC are presented as well as the accuracy with which the density of supersymmetric cold dark matter could be predicted from collider measurements.
121308441
B-quark production at 7 TeV with the CMS experiment
Measurements performed by the CMS experiment of the cross section for inclusive b-quark production in protonproton collisions at s = 7 TeV are presented. The measurements are based on data collected in 2010. The measurements are performed using different methods, such as inclusive jet measurements with secondary vertex tagging or selecting a sample of events containing jets and at least one muon, where the transverse momentum of the muon with respect to the closest jet axis discriminates b events from the background. The measurements of the total and single differential cross sections for B+, B0 and Bs mesons are also presented. The results are compared with predictions based on perturbative QCD calculations at leading and next-to-leading order.
115852037
Beauty in gamma gamma at LEP and determination of the b quark mass
204171619
Total two photon hadronic cross-section and charm production cross-section measurement with the L3 detector
122971502
Design principles of the end cap drift chambers in the L3 experiment
Abstract The end cap detector based on multimodule construction has been designed and produced for the L3 experiment. The purpose of this article is to present a fruitful approach for solving the complex problem of selecting a set of strongly interrelated design parameters to satisfy performance criteria in the face of severe environmental and space constraints. The design principle of the end cap drift chamber affected by a complex of external problems caused by the layout is reviewed. It is shown that in the framework of detailed consideration of each parameter, a good space–time linearity, spatial and angular resolution is obtainable. The results of experimental tests are presented.
102408955
THE INVESTIGATION OF THE DRIFT CHAMBER EFFICIENCY OPERATING IN PURE HYDROGEN AND HELIUM FOR PRESSURES UP TO 9-ATM
125792222
THE ELECTRON TRANSITION RADIATION DETECTOR IN THE EXPERIMENT TO MEASURE THE ASYMMETRY IN THE BETA DECAY OF POLARIZED SIGMA- HYPERONS
118144507
Search for narrow pion-proton states in s-channel at EPECUR: experiment status
An experiment EPECUR, aimed at the search of the cryptoexotic non-strange member of the pentaquark antidecuplet, started its operation at a pion beam line of the ITEP 10 GeV proton synchrotron. The invariant mass range of the interest (1610-1770) MeV will be scanned for a narrow state in the pion-proton and kaon-lambda systems in the formation-type experiment. The scan in the s-channel is supposed to be done by the variation of the incident pi- momentum and its measurement with the accuracy of up to 0.1% with a set of 1 mm pitch proportional chambers located in the first focus of the beam line. The reactions under the study will be identified by a magnetless spectrometer based on wire drift chambers with a hexagonal structure. Because the background suppression in this experiment depends on the angular resolution, the amount of matter in the chambers and setup is minimized to reduce multiple scattering. The differential cross section of the elastic pi-p-scattering on a liquid hydrogen target in the region of the diffractive minimum will be measured with statistical accuracy 0.5% in 1 MeV steps in terms of the invariant mass. For KLambda-production the total cross section will be measured with 1% statistical accuracy in the same steps. An important byproduct of this experiment will be a very accurate study of Lambda polarization. The setup was assembled and tested in December 2008 and in April 2009 we had the very first physics run. About 0.5x10^9 triggers were written to disk covering pion beam momentum range 940-1135 MeV/c.