Search results for " Error."
showing 10 items of 1034 documents
V-us determination from hyperon semileptonic decays
2005
16 páginas, 9 tablas.-- arXiv:hep-ph/0509045v2
Evaluation using m.c.n.p. code of the bremsstrahlung energy spectrum produced by interactions between structural materials and accelerated electrons
2004
Abstract In order to design the biological shield of industrial accelerator plants, it is needed to have a good knowledge of the bremsstrahlung energy spectrum and the intensity of the bremsstrahlung produced by electron interactions with both products (usually water equivalent) and structural materials such as concrete, iron, aluminium. Using the MCNP code, a normalized bremsstrahlung energy spectrum was obtained for materials with average atomic number lower than or equal to 13 and irradiated with 5 and 10 Mev electrons, respectively; multiplying the spectrum by suitable coefficients, it was possible to obtain the real spectrum for materials such as water, concrete, aluminium and iron. Th…
Extraction of cluster parameters with future Sunyaev-Zel'dovich observations
2003
The Sunyaev-Zel'dovich (SZ) effect of galaxy clusters is characterized by three parameters: Compton parameter, electron temperature and cluster peculiar velocity. In the present study we consider the problem of extracting these parameters using multi-frequency SZ observations only. We show that there exists a parameter degeneracy which can be broken with an appropriate choice of frequencies. As a result we discuss the optimal choice of observing frequencies from a theoretical point of view. Finally, we analyze the systematic errors (of the order micro K) on the SZ measurement introduced by finite bandwidths, and suggest a possible method of reducing these errors.
Measurement of the Neutron Electric to Magnetic Form Factor Ratio atQ2=1.58 GeV2Using the ReactionHe→3(e→,e′n)pp
2013
A measurement of beam helicity asymmetries in the reaction $^{3}\stackrel{\ensuremath{\rightarrow}}{\mathrm{He}}(\stackrel{\ensuremath{\rightarrow}}{e},{e}^{\ensuremath{'}}n)pp$ is performed at the Mainz Microtron in quasielastic kinematics to determine the electric to magnetic form factor ratio of the neutron ${G}_{E}^{n}/{G}_{M}^{n}$ at a four-momentum transfer ${Q}^{2}=1.58\text{ }\text{ }{\mathrm{GeV}}^{2}$. Longitudinally polarized electrons are scattered on a highly polarized $^{3}\mathrm{He}$ gas target. The scattered electrons are detected with a high-resolution magnetic spectrometer, and the ejected neutrons are detected with a dedicated neutron detector composed of scintillator ba…
Analysis and calibration of absorptive images of Bose-Einstein condensate at non-zero temperatures
2008
We describe the method allowing quantitative interpretation of absorptive images of mixtures of BEC and thermal atoms which reduces possible systematic errors associated with evaluation of the contribution of each fraction. By using known temperature dependence of the BEC fraction, the analysis allows precise calibration of the fitting results. The developed method is verified in two different measurements and compares well with theoretical calculations and with measurements performed by another group.
Total photoabsorption cross section for4He from 200 to 800 MeV
1997
The total photoabsorption cross section for ${}^{4}$He has been measured for the first time over a wide photon energy range (200 MeV$l~{E}_{\ensuremath{\gamma}}l~$800 MeV). By using the large acceptance detector DAPHNE at the tagged photon facility of the MAMI microtron in Mainz high precision results with small systematic errors were obtained. This measurement shows that ${}^{4}$He has a behavior similar to heavy nuclei and, in particular, a reduction of the cross section with respect to the lighter nuclei is found for ${E}_{\ensuremath{\gamma}}g$600 MeV.
New methods of evaluation of the flavor composition in e+ e- annihilation by double hemisphere tagging at LEP / SLC energies
1995
Two new methods are proposed to extract the flavour contents of the events produced at LEP/SLC, together with the classification matrix of a tagging by hemispheres. By utilising the tagging obtained in both hemispheres, the efficiencies, backgrounds and flavour compositions are directly obtained by fitting the data. A minimal dependence on modelling and a consistent treatment of systematic errors are achieved by applying these methods. The choice of the tagging algorithm is irrelevant in the methods, provided that similar efficiencies are reached. As an example, a multivariate analysis technique combining the tracking information given by a microvertex detector has been applied to extract t…
Determination of the number of J/psi events with J/psi -> inclusive decays
2012
The number of J/psi events collected with the BESIII detector at the BEPC II from June 12 to July 28, 2009 is determined to be (225.3 +/- 2.8) x 10(6) using J/psi -> inclusive events, where the uncertainty is the systematic error and the statistical one is negligible.
Backtracing particle rays through magnetic spectrometers: avoiding systematic errors in the reconstruction of target coordinates
1993
Abstract The procedures used to model [J. Friedrich, Nucl. Instr. and Meth. A 293 (1990) 575] or to determine [N. Voegler et al., Nucl. Instr. and Meth. A 249 (1986) 337, H. Blok et al., ibid., vol. A 262 (1987) 291, and E.A.J.M. Offermann et al., ibid., vol. A 262 (1987) 298] the mapping properties of a magnetic spectrometer are based on a minimization of the variance of target coordinates . We show that backtracing with matrix elements, determined in this way, may contain systematic errors. As alternative, we propose to minimize the variance of the detector coordinates . This procedure avoids these systematic errors.
A high statistics lattice calculation of the B-meson binding energy
1996
We present a high statistics lattice calculation of the B--meson binding energy $\overline{\Lambda}$ of the heavy--quark inside the pseudoscalar B--meson. Our numerical results have been obtained from several independent numerical simulations at $\beta=6.0$, $6.2$ and $6.4$, and using, for the meson correlators, the results obtained by the APE group at the same values of $\beta$. Our best estimate, obtained by combining results at different values of $\beta$, is $\overline{\Lambda}=180^{+30}_{-20}$ MeV. For the $\overline{MS}$ running mass, we obtain $\overline{m}_{b}(\overline{m}_{b})=4.15 \pm 0.05 \pm 0.20$ GeV, in reasonable agreement with previous determinations. The systematic error is…