122673523
Correlated measurements of secondary cosmic ray fluxes by the Aragats Space-Environmental Center monitors
Abstract The Aragats Space-Environmental Center provides monitoring of different species of secondary cosmic rays at two altitudes and with different energy thresholds. One-minute data is available on-line from http://crdlx5.yerphi.am/DVIN/index2.php . We present description of the main monitors along with data acquisition electronics. Also we demonstrate the sensitivity of the different species of secondary cosmic ray flux to geophysical conditions, taking as examples the extremely violent events of October–November 2003. We introduce correlation analysis of the different components of registered time-series as a new tool for the classification of the geoeffective (events on earth affected by solar activity) events and for the forecasting of the severity of the upcoming geomagnetic storm.
118030550
Comparison of GEANT4 Simulations with Testbeam Data and GEANT3 for the ATLAS Liquid Argon Calorimeter
We present several comparisons of GEANT4 simulations with test beam data and GEANT3 simulations for different liquid argon(LAr) calorimeters of the ATLAS detector,All relevant parts of the test beam setup(scintilators,multi wire proportional chambers,cryostat etc.)are described in GEANT4 as well as in GEANT3.Muon and electron data at different energies have been compared with Monte Carlo prediction.
197460273
Search for Yukawa production of a light neutral Higgs boson at LEP
Within a Two-Higgs-Doublet Model (2HDM) a search for a light Higgs boson in the mass range of 4–12 GeV has been performed in the Yukawa process \(\mathrme^+ \mathrme^-\rightarrow \mathrm{b}\bar{\mathrm{b}}\mathrm{A}/\mathrm{h}\rightarrow\mathrm{b} \bar{\mathrm{b}}\tau^+\tau^-\), using the data collected by the OPAL detector at LEP between 1992 and 1995 in \(\mathrme^+ \mathrme^-\) collisions at about 91 GeV centre-of-mass energy. A likelihood selection is applied to separate background and signal. The number of observed events is in good agreement with the expected background. Within a CP-conserving 2HDM type II model the cross-section for Yukawa production depends on \(\xi^{\mathrm{A}}_d=|\tan\beta|\) and \(\xi^{\mathrm{h}}_d=|\sin\alpha/\cos\beta|\) for the production of the CP-odd A and the CP-even h, respectively, where \(\tan\beta\) is the ratio of the vacuum expectation values of the Higgs doublets and \(\alpha\) is the mixing angle between the neutral CP-even Higgs bosons. From our data 95% C.L. upper limits are derived for \(\xi^{\mathrm{A}}_d\) within the range of 8.5 to 13.6 and for \(\xi^{\mathrm{h}}_d\) between 8.2 to 13.7, depending on the mass of the Higgs boson, assuming a branching fraction into \(\tau^+\tau^-\) of 100%. An interpretation of the limits within a 2HDM type II model with Standard Model particle content is given. These results impose constraints on several models that have been proposed to explain the recent BNL measurement of the muon anomalous magnetic moment.
122726428
FELIX: A Full acceptance detector at the LHC: Letter of intent
The FELIX Collaboration proposes the construction of a full acceptance detector for the LHC, to be located at Intersection Region 4, and to be commissioned concurrently with the LHC. The primary mission of FELIX is the study of QCD: to provide comprehensive and definitive observations of a very broad range of strong-interaction processes. This document contains a description of the detector concept including details of the individual detector elements and their performance characteristics, an extensive discussion of the physics menu, and the plans for integration of FELIX into the collider lattice and physical environment.
122000305
A measurement of the energy loss spectrum of 150 GeV muons in iron
The energy loss spectrum of 150 GeV muons has been measured with a prototype of the ATLAS hadron calorimeter in the H8 beam of the CERN SPS. The differential probability ${\rm {d}}P/{\rm {d}}v$ per radiation length of a fractional energy loss $v = \Delta E_{\mu} / E_{\mu}$ has been measured in the range $v$ = 0.01 $\div$ 0.95; it is compared with the theoretical predictions for energy losses due to bremsstrahlung and production of electron-positron pairs or of energetic knock-on electrons. The integrated probability $\int_{0.01}^{0.95} ({\rm {d}}P/{\rm {d}}v) {\rm {d}}v$ is $(1.610\pm0.015_{{\rm {stat}}}\pm0.105_{{\rm {syst}}})\cdot10^{-3}$ in agreement with the theoretical predictions $1.556\cdot10^{-3}$ and $1.619\cdot10^{-3}$. Agreement with theory is also found in two intervals of $v$ where production of electron-positron pairs and knock-on electrons dominates. In the region of bremsstrahlung dominance ($v$ = 0.12 $\div$~0.95) the measured integrated probability $(1.160\pm0.040_{{\rm {stat}}}\pm0.075_{{\rm {syst}}})\cdot 10^{-4}$ is in agreement with the theoretical value of $1.185 \cdot 10^{-4} $, obtained using the Petrukhin and Shestakov description of the bremsstrahlung process. The same result is about 3.6 standard deviations (defined as the quadratic sum of statistical and systematic errors) lower than the theoretical prediction of $ 1.472\cdot 10^{-4}$, obtained using Tsai's description of bremsstrahlung.
121450723
Single π--meson photoproduction on neutrons by linearly polarised photons in the third and fourth resonance region
The cross section asymmetry Sigma for the reaction gamma n to pi -p by linearly polarised photons was measured in the energy range Egamma =0.8-1.75 GeV and pion CM angles between 45 and 90 degrees . The results are compared with the predictions of phenomenological models.
122915783
Detection of high energy solar protons during ground level enhancements
Abstract Registration of high energy solar protons by middle and low latitude particle monitors during ground level enhancements (GLE) is investigated. We have developed a comprehensive method, for revealing weak GLE signals. The main result of the method is estimation of probability of error for given value of observed signal amplitude. We derived, that for middle energy protons, the 99% confidence limit of GLE signal detection is determined by ∼4.3 σ of observed signal, whereas for highest energy protons it is determined by ∼3.7 σ . Applying this method to GLE-65 at 28 October 2003, GLE-69 at 20 January 2005 and GLE-70 at 13 December 2006, we make conclusions about the maximal energy of protons during these events. We claim on the presence of >20…30 GeV protons in GLE-65 with the probability of error ∼7% and in the GLE-69 with the probability of error ∼0.4%. However, during GLE-70 maximal energy of protons was ∼10 GeV.
120704929
The analysis of proton- and deuteron-induced-reaction cross sections on tin isotopes at the beam energy of 3.65 GeV/nucleon
The total inelastic cross sections of the reactions of protons and deuterons on nuclear targets of enriched tin isotopes are compared. The factorization of cross sections of reactions is discussed. Furthermore, the comparison of theoretical estimations on total inelastic cross sections with corresponding experimental ones is made.
119436102
Application of stochastic resonance in gravitational-wave interferometer
We investigate a novel approach which improves the sensitivity of a gravitational-wave interferometer due to the phenomenon of stochastic resonance (SR), performing in a nonlinear cavity (NC). The NC is installed at the output of the interferometer before the photodetector so that the optical signal emerging from the interferometer passes through the NC. Under appropriate circumstances, a specific transformation of the noisy signal inside the NC takes place, which results in the increase of the output signal-to-noise ratio (SNR). As a result, the noisy optical signal of the interferometer becomes less noisy after passing through the NC. The improvement of SNR is especially effective in the bistable NC for wideband (several hundred Hz) detection, when the chirp gravitational-wave signal is detected. Then, for an input SNR of $\ensuremath{\sim}0.05$, the output SNR can be increased up to $\ensuremath{\sim}0.5$. When the detection bandwidth is narrowed, the SR mechanism gradually fades out, and the SNR gain tends to 1. The SNR gain also tends to 1 when the NC is transformed to a linear cavity. Proposed enhancement of the SNR due to SR is not dependent on noise type, which dominates in the interferometer. Particularly, the proposed approach is capable of increasing the SNR at a given amplitude of displacement noise.
119020922
Investigation of induced fission of natPb by accelerated 7Li ions
Cross-sections for fragments produced by the fission reaction induced by accelerated 7Li ions impinged into an natPb target at 245MeV were obtained. We have applied the induced-activation method in off-line analysis. The analysis of charge and mass distributions of fission products allowed the determination of the total fission cross-section for the 7Li+Pb system. The recoil technique (“thick target - thick catcher”), based on the two-step model mathematical formalism, is used to determine the kinematics characteristics of reaction products. The analysis concerning transferred linear momentum provided information on the initial projectile-target interaction, and is compared with proton-induced fission measurements.