Radiative rates, collision strengths and effective collision strengths for transitions in Gd XXXVII

Energy levels and radiative rates for transitions among 107 fine-structure levels belonging to the (1s(2)2S(2)p(6)) 3S(2)3p(6)3d(10), 3S(2)3p(6)3d(9)4e. 3S(2)3p(5)3d(10)4e. and 3s3p(6)3d(10)4e configurations of Ni-like Gd XXXVII have been calculated using the fully relativistic GRASP code. Radiative rates and oscillator strengths are tabulated for all allowed transitions among these levels. Additionally. collision strengths for transitions among the lowest 59 levels have been computed using the Dirac Atomic R-matrix Code. Resonances in the threshold region have been delineated, but results for collision strengths are tabulated only at energies above thresholds in the range 120

Oscillator strengths for transitions in C-like ions between K XIV and Mn XX

Energy levels and oscillator strengths (transition probabilities) have been calculated for transitions among 46 fine-structure levels of the (1s(2)) 2s(2) 2p(2), 2s2p(3),2p(4), 2s(2)2p3s, 2s(2) 2p3p and 2s(2)2p3d configurations of C-like K XIV, Sc XVI, Ti XVII, V XVIII, Cr XIX and Mn XX using the GRASP code. Configuration interaction and relativistic effects have been included while generating the wavefunctions. Calculated values of energy levels agree within 3% with the experimentally compiled results, and the length and velocity forms of oscillator strengths agree within 20% for a majority of allowed transitions.

Oscillator strengths for transitions in C-like ions between FIV and Ar XIII

Energy levels and oscillator strengths (transition probabilities) have been calculated for the fine-structure transitions among the levels of the (1s(2)) 2s(2)2p(2), 2s2p(3), 2p(4), 2s(2)2p3s, 2s(2)2p3p, and 2s(2)2p3d configurations of C-like F IV, Na VI, Al VIII, P X, Cl XII, and Ar XIII using the CIV3 program. The extensive configuration interaction and relativistic effects have been included while generating the wavefunctions. Calculated values of energy levels generally agree within 5% with the experimentally compiled results, and the length and velocity forms of oscillator strengths agree within 20% for a majority of allowed transitions.

Electron impact excitation of A1 XIII: A relativistic approach

Energy levels, radiative rates, collision strengths, and effective collision strengths for all transitions up to and including the n = 5 levels of AlXIII have been computed in the j j coupling scheme including relativistic effects. All partial waves with angular momentum J less than or equal to 60 have been included, and resonances have been resolved in a fine energy grid in the threshold region. Collision strengths are tabulated at energies above thresholds in the range 170.0 less than or equal to E less than or equal to 300.0 Ryd, and results for effective collision strengths, obtained after integrating the collision strengths over a Maxwellian distribution of electron velocities, are tabulated over a wide temperature range of 4.4 less than or equal to log T-e less than or equal to 6.8 K. The importance of including relativistic effects in a calculation is discussed in comparison with the earlier available non-relativistic results.

Electron impact excitation of Gd XXXVII and radiative rates for Ni-like ions with 60

Energy levels and radiative rates for transitions among the 107 finestructure levels belonging to the (1s(2)2s(2)2p(6)) 3s(2)3p(6)3d(10), 3s(2)3p(6)3d(9)4l, 3s(2)3p(5)3d(10)4l, and 3s3p(6)3d(10)4l configurations of Ni-like ions with 60 less than or equal to Z less than or equal to 90 have been calculated using the GRASP code. The collision strengths (Omega) have also been computed for transitions in Gd XXXVII at energies below 800 Ryd, using the DARC code. Resonances have been resolved in a fine energy mesh in the threshold region, and excitation rate coefficients have been calculated for transitions from the ground level to excited levels at temperatures below 2500 eV. These have been compared with those available in the literature, and enhancement in the values of rates, due to resonances, has been observed up to an order of magnitude for some of the transitions.

Relativistic allowed and forbidden transition probabilities for fluorine-like Fe XVIII

Energy levels and the corresponding transition probabilities for allowed and forbidden transitions among the levels of the ground configuration and first 23 excited configurations of fluorine-like Fe XVIII have been calculated using the multiconfigurational Dirac-Fock GRASP code. A total of 379 lowest bound levels of Fe XVIII is presented, and the energy levels are identified in spectroscopic notations. Transition probabilities, oscillator strengths and line strengths for electric dipole (E1), electric quadrupole (E2) and magnetic dipole (M1) transitions among these 379 levels are also presented. The calculated energy levels and transition probabilities are compared with experimental data.

An investigation into the use of atomic datasets in simulations of the Ni-like gadolinium x-ray laser

The effect of differing the datasets used in the modelling of the Ni-like Gd x-ray laser (XRL) is examined through the 1.50 hydro-atomic code, EHYBRID. Two atomic datasets, including energy levels and radiative and collisional excitation rates, are used as input data for the code. It is found that the behaviour of the XRL is somewhat different than might be expected from superficial examination of the atomic data. The similarities in the gain profiles at low densities are found to have encouraging implications. in our attempts to model XRLs.

Inner-shell photoexcitation of Fe XV and Fe XVI

The configuration-interaction method as implemented in the computer code CIV3 is used to determine energy levels, electric dipole radiative transition wavelengths, oscillator strengths and transition probabilities for inner-shell excitation of transitions in Fe XV and Fe XVI. Specifically, transitions are considered of the type 1s(2) 2s(2) 2p(6) 3s(2) -1s(2) 2s(2) 2p(5) 3l3l' 3l" (l, l' and l" = s,p or d) in FeXV and 1s(2) 2s(2) 2p(6) 3s- 1s(2) 2s(2) 2p(5) 3l3l' (l and l' = s,p or d) in FeXVI, using the relativistic Breit-Pauli approach. An assessment of the accuracy of the derived atomic data is performed.

Electron impact excitation of Fe XVI: radiative and excitation rates

Aims. In this paper we report calculations for energy levels, radiative rates, collision strengths, and effective collision strengths for transitions in Fe XVI. Methods. For energy levels and radiative rates we have used the General purpose Relativistic Atomic Structure Package ( grasp), and for the compuations of collision strengths the Dirac Atomic R-matrix Code (darc) has been adopted. Results. Energies for the lowest 39 levels among the n

Ionization energies of beryllium in strong magnetic fields: a frozen core approximation

An effective frozen core approximation has been developed and applied to the calculation of energy levels and ionization energies of the beryllium atom in magnetic field strengths up to 2.35 x 10(5) T. Systematic improvement over the existing results for the beryllium ground and low-lying states has been accomplished by taking into account most of the correlation effects in the four-electron system. To our knowledge, this is the first calculation of the electronic properties of the beryllium atom in a strong magnetic field carried out using a configuration interaction approximation and thus allowing a treatment beyond that of Hartree-Fock. Differing roles played by strong magnetic fields in intrashell correlation within different states are observed. In addition, possible ways to gain further improvement in the energies of the states of interest are proposed and discussed briefly.

Superfluid toroidal currents in atomic condensates

The spectrum of collective excitations of oblate toroidal condensates within the Bogoliubov approximation was studied, and the dynamical stability of ring currents around the torus explored. The transition from spheroidal to toroidal geometry of the trap displaced the energy levels into narrow bands. A simple, but accurate, formula was detailed for the lowest angular acoustic modes of excitation, and the splitting energy when a background current is present.

Radiative rates and electron impact excitation rates for H-like Ar XVIII

Aims. In this paper we report on calculations for energy levels, radiative rates, collision strengths, and effective collision strengths for
transitions among the lowest 25 levels of the n ≤ 5 configurations of H-like Ar xviii.
Methods. The general-purpose relativistic atomic structure package (grasp) andDirac atomic R-matrix code (darc) are adopted for
the calculations.
Results. Radiative rates, oscillator strengths, and line strengths are reported for all electric dipole (E1), magnetic dipole (M1), electric
quadrupole (E2), and magnetic quadrupole (M2) transitions among the 25 levels. Furthermore, collision strengths and effective
collision strengths are listed for all 300 transitions among the above 25 levels over a wide energy (temperature) range up to 800 Ryd
(107.4 K).

Comment on "Electron collisional excitation of argon-like Ni XI using the Breit-Pauli R-matrix method" [Eur. Phys. J. D 42, 235-241 (2007)] - Electron impact excitation of Ni XI

In a recent paper, Verma et al. [Eur. Phys. J. D 42, 235 (2007)] have reported results for energy levels, radiative rates, collision strengths, and effective collision strengths for transitions among the lowest 17 levels of the (1s(2)2s(2)2p(6))3s(2)3p(6), 3s(2)3p(5)3d and 3s3p(6)3d configurations of Ni XI. They adopted the CIV3 and R-matrix codes for the generation of wavefunctions and the scattering process, respectively. In this paper, through two independent calculations performed with the fully relativistic DARC (along with GRASP) and FAC codes, we demonstrate that their results are unreliable. New data are presented and their accuracy is assessed.

Electron impact excitation of S-like iron

Energy levels and radiative rates for transitions among the lowest 48 fine-structure levels belonging to the (1s(2) 2s(2) 2p (6)) 3s (2)3p (4) , 3s3p(5), 3s (2)3p (3) 3d and 3p(6) configurations of Fe xi have been calculated using the fully relativistic grasp code. Additionally, collision strengths for transitions among these levels have also been computed using the Dirac Atomic R-matrix Code (darc) of Norrington & Grant. Radiative rates and oscillator strengths are tabulated for all allowed transitions among the 48 fine-structure levels, while collision strengths are reported at three energies above thresholds, i.e. 8, 16 and 24 Ryd for a few representative transitions. Furthermore, excitation rates have been calculated in a wide electron temperature range below 5 x 10(6) K, and the contribution of resonances has been included in the threshold regions. Comparisons are made with the earlier available theoretical and experimental rates, and it is concluded that the experimental rates are overestimated by up to a factor of 2.

Paul Karl Feyerabend Las proyecciones de la proliferación teórica en la relación ciencia-metafísica

La doctrina de la Proliferación teórica de Paul Karl Feyerabend ha sido interpretada por sus especialistas como un intento de salvaguardar el ideal del progreso científico. Aunque tales estudios hacen justicia, en parte, a la intencionalidad de nuestro filósofo no explicitan la crítica fundamental que implica para Feyerabend el pluralismo teórico. La proliferación teórica constituye en sí misma una reductio ad absurdum de los distintos intentos del positivismo lógico y del racionalismo crítico por definir la ciencia a expensas de lo metafísico. Este artículo presenta la proliferación teórica como una reivindicación del papel positivo que ocupa la metafísica en el quehacer científico. Se consigna la defensa que hace Feyerabend de la metafísica en cuanto que ésta constituye la posibilidad de superar el conservadurismo conceptual, aumentar de contenido empírico de la ciencia y recuperar el valor descriptivo de las teorías científicas.