124294098
Target residues formed in the 4.4 GeV deuteron-induced reaction on gold
The production cross sections for 110 radioactive nuclides, with mass numbers 22 A 198, were obtained from the interaction of 4.4 GeV deuteron with a 197 Au target using the induced-activity method. The deuteron beam was obtained from the Nuclotron of the Laboratory of High Energies (LHE), Joint Institute for Nuclear Research (JINR) at Dubna. Using the charge distribution data, we derived the total mass-yield distribution. The analysis of the mass-yield distribution allowed us to consider the coexistence of different channels in the interaction such as evaporation, fission, and multifragmentation.
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.
118419146
Proton-induced fission on241Am,238U, and237Np at intermediate energies
Intermediate energy data of proton-induced fission on ${}^{241}$Am, ${}^{238}$U, and ${}^{237}$Np targets were analysed and investigated using the computational simulation code crisp. Inelastic interactions of protons on heavy nuclei and both symmetric and asymmetric fission are regarded. The fission probabilities are obtained from the crisp code calculations by means of the Bohr-Wheeler model. The fission cross sections, the fissility and the number of nucleons evaporated by the nuclei, before and after fission, are calculated and compared with experimental data. Some of the model predictions agree completely with the data. We conclude that our two step model of the crisp code provides a good description of intermediate energy proton-induced fission.
119281187
Recoil properties of fragments formed in 4.4 GeV deuteron-induced reactions on a gold target
The recoil properties of fragments produced by the interaction of 4.4 GeV deuterons with a ${}^{197}$Au target have been studied. New experimental data on recoil properties for 90 nuclei, varying from ${}^{24}$Na to ${}^{198}$Au, were obtained. The technique applied was the thick-target thick-catcher and induced activity method. The deuteron beam was obtained from the Nuclotron of the Laboratory of High Energies (LHE), Joint Institute for Nuclear Research (JINR), Dubna. The experimental data were analyzed on the basis of the standard two-step vector model formalism. From the analysis of the reaction investigated here, we could find evidence that the cooling process of excited nuclei can be due to the coexistence of different decay modes such as evaporation, fission, and (multi)fragmentation. Fission and multifragmentation can contribute appreciably to the formation of products in the intermediate mass range. The kinematic characteristics of residual nuclei formed in the present deuteron-induced reaction have been compared to those from proton-induced reactions with gold target.
119300484
Fission of pre-actinide nuclei
A study of photofission on 181Ta nucleus induced by bremsstrahlung photons with endpoint energies of 50 and 3500 MeV has been performed. The fission yields have been measured by using the induced-activity method in an off-line analysis. The absolute photofission cross sections for the tantalum target at 50 and 3500 MeV are found to be 5.4 \pm 1.1 microb and 0.77\pm0.11 mb, respectively, and the corresponding deduced fissilities are (0.23\pm0.05) x 10^{-3} and (2.9 \pm 0.9) x 10^{-3}. Mass- and charge-yield distributions were derived from the data. The results were compared with the simulated results from CRISP code for multi-modal fission by assuming symmetrical fission mode.
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.
122778557
Statistical methods for signal estimation of point sources of cosmic rays
The estimation of the significance of the peaks in one- and two-dimensional distributions is one of the most important problems in high-energy physics and astrophysics. The physical inference from low-statistics experiments usually is biased and many discoveries lack further confirmation. One of the typical mistakes in physical inference is the use of non-adequate statistical models. We analyze the significance of the experimental evidence in the on-going efforts of detecting the point source of cosmic rays. We found that simple statistical models (Gaussian or Poisson) did not adequately describe the experimental situation of point source searches. To avoid drawbacks related to usage of the incorrect statistical model, we introduce new extremum statistical models appropriate for the point source searches. The analysis is conducted in the framework of two models utilizing extremum statistics: first – using the fixed grid of celestial coordinates, and second – using the tuned grid (introducing more degrees of freedom in the search). The test distributions for the significance estimation are obtained both from simulation models and from the analytical model of extremum statistics. We show that the second model gives adequate physical inference, while the first model can lead to the positively biased conclusions of the point source significance.
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.
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.
123495063
Directivity function of muon detector
Abstract We introduce a new concept of directivity function (DF) to describe directional sensitivity of a particle detector. DF is а 3D function, describing the sensitivity of a detector to asymptotic directions of primary protons. It defines the contribution of primary protons, arriving from different asymptotic directions to the count rate of the detector. We develop the approach for computing the DF and derive it in particular case of SEVAN muon detector, located at mount Aragats, Armenia. Obtained data enable one to outline the region of solid angles, inside of which the arriving protons contribute a given percentage of count rate. In general, the DF can have the multi peak shape. It provides the most detailed and accurate description of directional sensitivity of a particle detector and we suggest that it is used in space research based on neutron and muon detectors.
119078457
Advanced configuration of gravitational-wave interferometer on the base of “sensitive mode” in “white-light cavity”
Abstract A novel conception of “sensitive mode” (SM) is proposed to apply in gravitational-wave advanced interferometer configuration (AIC). The SM is resonant oscillation of electromagnetic field in “white-light cavity”, where the resonance line is broadened without decreasing cavity quality. The resonant field frequency of the SM is greatly susceptible to the change of cavity length, and the SM is established in a cavity with time constant smaller than a conventional mode. Due to these advantages the sensitivity and bandwidth of AIC can be increased.