Results 1 - 10 of 317
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[en] The theory of the coherent creation of pairs by photon in the alignment crystal under conditions when the created electron and positron moving in the axial channeling regime is developed. In this case combined effect takes place which consist in a broadening of the width and changing of the shape and to appearance of the fine structure of the coherent peaks.
[en] Using a linked-parametric technique of level-fitting calculations in a multiconfiguration basis, a parametric fine structure (fs) analysis for both even and odd parities of Cr II was achieved. For the first time the fs parameter, magnetic Landé -factor and the percentage of leading eigenvector values for more than one thousand levels are determined and given for these two sets. This study has led us to confirm in the whole the well founded basis of NIST team works but inevitably also to exchange assignments of some levels classified in earlier lists of energy levels and to shift positions of some quartets like for instance. Furthermore we take this opportunity to add our predicted doublet, quartet and sextet locations for missing experimental levels up to 124,000 cm−1.
[en] We study the CDM models with being a function of the time-varying fine structure constant . We give a close look at the constraints on two specific CDM models with one and two model parameters, respectively, based on the cosmological observational measurements along with 313 data points for the time-varying . We find that the model parameters are constrained to be around , which are similar to the results discussed previously but more accurately.
[en] This work discusses the observation of splitting in the energy levels of prolate nuclei. Similar effects in atomic physics are known as the Zeeman effect, but in nuclear physics the feasibility of such phenomena has not been observed. After introducing a deformation in the commutation relation in three dimensions, we used these commutation relations in X(3) model. After enough derivation, we then evaluate the energy spectrum relation for the considered system, which has resulted in energy splitting. With these observations in the energy splitting we referred to such an effect as the ultra-fine structures in energy levels. At the end some plots have been depicted to illustrate the results. (author)
[en] The effect of flux trapping on the flux-voltage characteristics of multi-loop SQUID magnetometers was investigated by means of repeated cool-down cycles in a stepwise increased magnetic background field. For a SQUID with N parallel loops, N different flux offsets, each separated by were observed even in zero magnetic field. These flux offsets further split into a so called fine structure, which can be explained by minor asymmetries in the SQUID design. The observed results are discussed with particular regard to their impact on the previously presented absolute SQUID cascade vector magnetometer. (paper)
[en] A method is proposed for calculating the rate constants of inelastic processes occurring during collisions of alkali metal atoms and their positive ions with hydrogen atoms and negative ions, taking into account the sublevels of the fine structure of alkali metal levels. The results of the application of the proposed method are presented in this paper based on the example of the KH and RbH collisional systems.
[en] High precision measurements of fast ion effects on the magnetic equilibrium in the ASDEX Upgrade tokamak have been conducted in a high-power (10 MW) neutral-beam injection discharge. An improved analysis of the spectral motional Stark effect data based on forward-modeling, including the Zeeman effect, fine-structure and non-statistical sub-level distribution, revealed changes in the order of 1% in . The results were found to be consistent with results from the equilibrium solver CLISTE. The measurements allowed us to derive the fast ion pressure fraction to be and variations of the fast ion pressure are consistent with calculations of the transport code TRANSP. The results advance the understanding of fast ion confinement and magneto-hydrodynamic stability in the presence of fast ions. (paper)
[en] We investigate the dielectronic recombination (DR) of an electron and a highly-charged ion with non-zero nuclear spin. We assume that the incident electron is captured into doubly-excited levels of Be-like ions just above of its autoionization threshold. The angular distribution of the subsequent radiative emission is investigated especially for its dependence upon the nuclear spin and the nuclear magnetic moment. While the hyperfine and even the fine-structure of the ions cannot be resolved in typical DR experiments, we found the photon angular distribution, following the decay of the DR resonance very sensitive to the nuclear parameters.
[en] Highlights: • The 2D-PESs for SiH(2A′)-He and SiH(2A″)-He have been computed at the RCCSD(T)/cc-pVQ-F12 level. • The depths of the global minima on both PESs are −84.7 and −11.6 cm−1 respectively for SiH(2A″)-He and SiH(2A′)-He. • The rotational cross sections and collisional rate coefficients have been derived. • Our calculations show a propensity rule that favors ΔJ = 2 transitions, for parity conserving. • These calculations also show, for parity breaking, a propensity rule that favors ΔJ = 1 transitions. New adiabatic potential energy surfaces (PESs) for and states of SiH(X)-He() complex have been calculated at the restricted coupled cluster level of theory including single, double and triple excitation [RCCSD(T)]. The RKHS method was used for the analytic fit of these PESs. The resulting PESs were employed later in the close-coupling approach for the computation of the inelastic integral cross sections which take into account the fine-structure of the SiH radical. Scattering calculations, are done on a grid of collision energies large enough to ensure converged state-to-state rate coefficients for the temperature ranging from 8 K up to 300 K.