The algorithm for estimating muon fluxes after passing through extended objects is described. Based on this algorithm, the distributions of muon characteristics for iron and soil of various ...thicknesses are obtained. The data obtained are compared with simulation results using the GEANT4 package. The minimum sizes of a soil cavity, at which its detection by muon radiography is possible, were estimated.
The OPERA experiment, designed to perform the first observation of
ν
μ
→
ν
τ
oscillations in appearance mode through the detection of the
τ
leptons produced in
ν
τ
charged current interactions, has ...collected data from 2008 to 2012. In the present paper, the procedure developed to detect
τ
particle decays, occurring over distances of the order of
1
mm
from the neutrino interaction point, is described in detail and applied to the search for charmed hadrons, showing similar decay topologies as the
τ
lepton. In the analysed sample, 50 charm decay candidate events are observed while
54
±
4
are expected, proving that the detector performance and the analysis chain applied to neutrino events are well reproduced by the OPERA simulation and thus validating the methods for
ν
τ
appearance detection.
The OPERA detector, designed to search for v.sub.μ right arrow v.sub.τ oscillations in the CNGS beam, is located in the underground Gran Sasso laboratory, a privileged location to study TeV-scale ...cosmic rays. For the analysis here presented, the detector was used to measure the atmospheric muon charge ratio in the TeV region. OPERA collected charge-separated cosmic ray data between 2008 and 2012. More than 3 million atmospheric muon events were detected and reconstructed, among which about 110000 multiple muon bundles. The charge ratio R.sub.μ = N.sub.μ + /N.sub.μ- was measured separately for single and for multiple muon events. The analysis exploited the inversion of the magnet polarity which was performed on purpose during the 2012 Run. The combination of the two data sets with opposite magnet polarities allowed minimizing systematic uncertainties and reaching an accurate determination of the muon charge ratio. Data were fitted to obtain relevant parameters on the composition of primary cosmic rays and the associated kaon production in the forward fragmentation region. In the surface energy range 1-20 TeV investigated by OPERA, R.sub.μ is well described by a parametric model including only pion and kaon contributions to the muon flux, showing no significant contribution of the prompt component. The energy independence supports the validity of Feynman scaling in the fragmentation region up to 200 TeV/nucleon primary energy.
A
bstract
The OPERA experiment, exposed to the CERN to Gran Sasso
ν
μ
beam, collected data from 2008 to 2012. Four oscillated
ν
τ
Charged Current interaction candidates have been detected in ...appearance mode, which are consistent with
ν
μ
→ ν
τ
oscillations at the atmospheric Δ
m
2
within the “standard” three-neutrino framework. In this paper, the OPERA
ν
τ
appearance results are used to derive limits on the mixing parameters of a massive sterile neutrino.
The OPERA detector at the Gran Sasso underground laboratory (LNGS) was used to measure the atmospheric muon charge ratio
in the TeV energy region. We analyzed 403069 atmospheric muons corresponding ...to 113.4 days of livetime during the 2008 CNGS run. We computed separately the muon charge ratio for single and for multiple muon events in order to select different energy regions of the primary cosmic ray spectrum and to test the
R
μ
dependence on the primary composition. The measured
R
μ
values were corrected taking into account the charge-misidentification errors. Data have also been grouped in five bins of the “vertical surface energy” ℰ
μ
cos
θ
. A fit to a simplified model of muon production in the atmosphere allowed the determination of the pion and kaon charge ratios weighted by the cosmic ray energy spectrum.
The classical biophysical Morris-Lecar model of neuronal excitability predicts that upon stimulation of the neuron with a sufficiently large constant depolarizing current there exists a finite ...interval of the current values where periodic spike generation occurs. Above the upper boundary of this interval, there is four-stage damping of the spike amplitude: 1) minor primary damping, which reflects a typical transient to stationary dynamic state, 2) plateau of nearly undamped periodic oscillations, 3) strong damping, and 4) reaching a constant asymptotic value of the neuron potential. We have shown that in the vicinity of the asymptote the Morris-Lecar equations can be reduced to the standard equation for exponentially damped harmonic oscillations. Importantly, all coefficients of this equation can be explicitly expressed through parameters of the original Morris-Lecar model, enabling direct comparison of the numerical and analytical solutions for the neuron potential dynamics at later stages of the spike amplitude damping.
This article is devoted to the methods of processing nuclear emulsions with an automatic scanning station. A description of the method of reconstruction for tracks located in the plane of the ...emulsion based on the Hough transform algorithm is given.
PDF
