Folded Cross Sections Research Articles

Studying supernova neutrinos through nuclear structure calculations

Differential and integrated cross section calculations are performed in the context of the quasi particle random phase approximation (QRPA) by utilizing realistic two- nucleon forces, for the 64,66 Zn isotopes, contents of the COBRA double beta decay detector. For these isotopes the response to supernova neutrinos is of current inter- est. The response of the 66 Zn isotope to the energy-spectra of supernova neutrinos is also explored by convoluting the original results for the differential cross sections by employing: (i) a two-parameter Fermi-Dirac (FD) and (ii) a Power-Law (PL) neutrino energy distribution. Such folded cross sections are useful in low-energy astrophysical-neutrino detection in underground terrestrial experiments.

Studying the coherent channel of neutral current ν-nucleus interaction

Original cross-sections calculations for neutral current neutrino scattering on 40Ar isotope are performed in the context of the quasi-particle random phase approximation (QRPA) by utilizing realistic two-nucleon forces. The incoming neutrino energy range adopted, εν ≤ 100 MeV, covers the supernova neutrinos, the low-energy beta-beam-neutrinos and the pion-muon stopped neutrino-beams existing or planned to be conducted at future neutron spallation sources. Subsequently, are the original cross sections convoluted with various supernova neutrino-energy distributions such as the two-parameter Fermi-Dirac and the power law distributions. The folded cross sections are obtained for various values of the parameters of these neutrino energy distributions corresponding to different supernova scenarios. One of the main purposes of this work is to explore the response of the 40Ar isotope as supernova neutrino detector.

Statistical analysis of distribution patterns of coal seams in fold zones in Northwest China

The mechanisms for rock bursts occurrences in fold zones are complex, and the redistribution of in-situ stresses is closely related to the complexity of the structures. Analysis of the geomorphology of fold structures and changes of coal thickness can help identify zones prone to rock bursts to improve safety and productivity in coal mines. This study investigated the distribution characteristics of fold structures in coal seams in fold zones in four mines in northwest China. Geometrical characteristics of fold structures in coal seams and changes of coal thickness were analysed, based on comprehensive evaluation indexes, such as the length–width ratio of folds, interlimb angle, ratio P1 of projected width of fold limbs to that of the hinge zone, curvature ratio P2, the maximum curvature and amplitude. The statistical analysis of the four coal mines shows that the length–width ratio of folds changed from 0.78 to 2.03 and the maximum curvature of cross sections of folds was less than 0.04. The curvature ratio of cross section of a fold in the structure was no more than 1.4 and the interlimb angles of cross sections of 89% of folds were larger than 150°. Gentle fold structures were dominant and the specific geological morphologies were domes or basins. The isopleth of coal thickness above the coal mines showed a fluctuation trend similar to the contour line of the floor of coal seams. The coal thickness in an anticline area was smaller than that in the neighboring syncline area. Therefore, the overall variation of coal thickness in the mining areas was likely to have a relation with the direction of the regional principal stress.

Neutrino scattering off the stable cadmium isotopes: II. Charged-current processes

The present study is a continuation of our previous work (2015 J. Phys. G: Nucl. Part. Phys. 42 025106) on neutral-current supernova-neutrino processes in the stable cadmium isotopes. Here we concentrate on the charged-current scattering processes of neutrinos off the stable cadmium isotopes covering an energy range characteristic of supernova neutrinos. As a theory framework we adopt the quasiparticle random-phase approximation in its charge-changing mode (pnQRPA) and the microscopic quasiparticle-phonon model to construct the required nuclear wave functions of the odd–odd and odd–even isobars of the stable even–even reference cadmium isotopes, respectively. The cross sections of the charged-current neutrino and antineutrino scatterings off the stable cadmium isotopes are subsequently computed. The nuclear responses to supernova neutrinos are also estimated by folding the cross sections with neutrino-energy spectra including the effects of matter oscillations within an effective two-neutrino framework. The calculations indicate that the folded cross sections have mass-number dependencies that are different for neutrinos and antineutrinos, and that odd-mass nuclei have relatively large cross sections. The matter oscillations affect the cross sections strongly and it is found that the computed averaged cross sections for antineutrinos differ notably for the normal/inverted mass hierarchy. This could have interesting consequences for the experimental solution of the mass-hierarchy problem in future large-scale neutrino telescopes.

Mechanical versus kinematical shortening reconstructions of the Zagros High Folded Zone (Kurdistan region of Iraq)

This paper compares kinematical and mechanical techniques for the palinspastic reconstruction of folded cross sections in collision orogens. The studied area and the reconstructed NE–SW trending, 55.5 km long cross section is located in the High Folded Zone of the Zagros fold‐and‐thrust belt in the Kurdistan region of Iraq. The present‐day geometry of the cross section has been constructed from field as well as remote sensing data. In a first step, the structures and the stratigraphy are simplified and summarized in eight units trying to identify the main geometric and mechanical parameters. In a second step, the shortening is kinematically estimated using the dip domain method to 11%–15%. Then the same cross section is used in a numerical finite element model to perform dynamical unfolding simulations taking various rheological parameters into account. The main factor allowing for an efficient dynamic unfolding is the presence of interfacial slip conditions between the mechanically strong units. Other factors, such as Newtonian versus power law viscous rheology or the presence of a basement, affect the numerical simulations much less strongly. If interfacial slip is accounted for, fold amplitudes are reduced efficiently during the dynamical unfolding simulations, while welded layer interfaces lead to unrealistic shortening estimates. It is suggested that interfacial slip and decoupling of the deformation along detachment horizons is an important mechanical parameter that controlled the folding processes in the Zagros High Folded Zone.

Influence of supernova-neutrino spectra on the neutrino signal in a terrestrial detector

Neutrino interactions on a $^{208}\mathrm{Pb}$ target nucleus are widely regarded as an excellent tool for the study of a galactic supernova explosion in a terrestrial detector. To serve this goal an accurate knowledge of the neutrino cross section on $^{208}\mathrm{Pb}$ is needed. We examine the influence of the supernova-neutrino energy spectrum on the response in a detector. In view of the results of recent calculations for supernova-neutrino spectra, we discuss the importance of the distribution's average energy and width and comment on the influence of uncertainties in the parametrization of the spectrum. We show that changes in the energy distributions parameters can have a disproportionately large influence on the folded cross section. Our calculations point out that implementing the new supernova-neutrino spectra causes a reduction of the folded supernova-neutrino cross sections. We note a remarkably large sensitivity of the folded cross sections to the high-energy tail of the spectrum. The discussion focuses on neutral-current reactions in a terrestrial detector considering one- and two-neutron knockout.