P. Verma

M-shell x-ray production cross section measurements in Pb and Bi due to the impact of protons and nickel ions

M-shell x-ray production cross sections in Pb have been measured using 58 - 82 MeV ions and those in Bi by 1 - 5 MeV protons and 58 - 82 MeV ions (q = 5, 6). The experimental results have been compared with the predictions of the plane-wave Born approximation (PWBA) and with the calculations of the perturbed stationary state theory (ECPSSR) accounting for the energy loss (E), Coulomb deflection (C) and relativistic (R) effects. The present results of proton impact on bismuth have also been compared with the experimental data available from other investigations. To the best of our knowledge, the M-shell x-ray production cross sections in Pb and Bi by Ni-ion impact are reported here for the first time. Good agreement of the present results with the predictions of the ECPSSR theory has been observed for the total M x-ray cross sections in Bi due to proton impact while discrepancies to a factor of 1.5 - 2.5 in the case of total M x-ray cross sections have been observed between the present experimental and theoretical (PWBA and ECPSSR, respectively) results for Pb and Bi in the case of Ni-ion impact. These discrepancies between the experimental and theoretical results could be attributed to the effect of multiple ionization on the x-ray emission probabilities. If the modified value of the average fluorescence yield accounting for the outer-shell multiple ionization is used, the theoretical results of total M-shell x-ray cross sections based on the PWBA theory show fair agreement with the experimental results (within experimental uncertainties) while the ECPSSR theory is found to underestimate the experimental results by about 40% for both Pb and Bi in the case of Ni-ion impact. Furthermore, the and x-ray cross sections have been evaluated experimentally for both Pb and Bi. The comparison of these results with the corresponding theoretical estimates have been done only for Pb as the emission rates for various M x-ray transitions of Bi are not available in the literature. The comparison of the cross sections show fair agreement with the PWBA-based theoretical values, while there are discrepancies of a factor of 10 and 20 in the cases of and x-ray transitions.

Measurement of M X-ray production cross sections in gold by proton, oxygen and nickel ion impact

Measurements of M-shell X-ray production cross sections in Au with proton, O5+- and Ni5+-ion impact have been performed. The energy of the incident protons range from 1 to 5 MeV, oxygen ions from 66 to 72 MeV and nickel ions from 58 to 87 MeV. The experimental results have been compared with the predictions of the plane wave Born approximation (PWBA) and the perturbed stationary state theory with energy loss, Coulomb deflection and relativistic corrections (ECPSSR). For proton impact the measured cross sections have been found to be in good agreement with both these theories. With O-ion impact the ECPSSR theory underpredicts the experimental data while the PWBA agrees fairly well. Both the theories, however, strongly underestimate the X-ray cross sections measured with Ni-ion impact. The discrepancy between the experimentally measured and theoretically calculated cross sections in case of heavy ion impact could be due to multiple ionization which changes the values of atomic parameters like sub-shell fluorescence yields, Coster-Kronig transition probabilities and emission rates.

Inner-shell couplings in transiently formed superheavy quasimolecules

The inner-shell couplings for Uq+-ions (73≤q≤91) moving moderately slow at ~69 MeV u−1 and bombarding thin Au targets have been investigated. Having established the definite survival probability of incoming projectile K vacancies in these targets in an earlier publication, the transfer of these vacancies to the target K-shell due to inner-shell couplings has been studied. As the system is in the quasiadiabatic collision regime for the K-shell of collision partners, advanced SCF-DFS (self-consistent field-Dirac–Fock–Slater) multielectron level diagrams have been used for interpretation. Using a simple model, the L–K shell coupling interaction distance has been estimated and compared with level diagram calculations.

Observation of enhancement in K-shell radiative recombination of U92+ ions with cooling electrons

The observation of the enhancement of radiative recombination (RR) into the K-shell for U92+ ions interacting with cooling electrons in x-ray RR experiment performed at the ESR storage ring is reported. From the measured intensities of K-RR x-rays for the electron relative energies in the range 0-1000 meV a clear indication of the recombination enhancement, with respect of the fully relativistic RR calculations, was found for the K-shell for the zero relative electron energy. This results add new aspects to existing interpretations of the enhancement effect emphasizing a role of recombination into high Rydberg states.

Alternatives for Energy Stressed Cities

In a world where nonrenewable fuel shortage is looming large, finding alternative sources of energy to satisfy energy requirements has become a matter of profound importance. Wind power and solar power are such alternatives. Trapping wind and solar energy in any manner could help us in this concern. Thus if this idea is realized, it has the potential to bring about not only substantial reduction in costs of fuels and carbon emission but also cut down the electricity bills thereby revolutionizing the concept of green energy as something phenomenal and beyond a niche of green-minded environmentalists. The idea of smart cities can be realized by making them self-sustainable. This can be done by installing a number of small turbines connected to same axis along with solar panels on top of all tall buildings of the smart city which will produce green electricity. Hence there will be a decrease in the consumption of nonrenewable resources like petroleum and coal which leads to the emission of various toxic gases and waste products causing harm to the environment. Planning for underground metros will be essential for a smart city in order to save space and time. Clean electricity can also be generated by installation of wind turbines in underground metros. This will not only help to generate electricity but also decrease the number of cars on road which in turn will decrease the pollution.

Molecular orbital perspective for inner shell couplings: Level diagrams

Level diagrams drawn for the Ag-Gd, Ho and Yb collision systems allow a qualitative explanation for the experimentally observed enhanced target and projectile cross sections. Super heavy quasimolecules formed during these slow, heavy-ion, heavy-atom collisions act as a beacon of light to investigate the couplings of the inner shells and the dependence of inner shell ionization on projectile charge state.

Enhanced radiative recombination of U92+ ions with cooling electrons for the K-shell

Observed enhancement of K-shell radiative recombination (RR) of bare uranium ions with cooling electrons is interpreted in terms of of distant transverse collisions in magnetized electron-cooler plasma described within the semiclassical geometrical model (SGM), which was recently proposed. The Monte Carlo simulations based on the proposed approach explains the enhancement measured in RR of U92+ ions with cooling electrons for the K-shell.

Shell-differential electron capture in heavy ion-atom collisions at moderate collision velocities

Electron capture cross sections have been estimated from the projectile incoming inner shell vacancy dependent K and L x-ray emission cross sections of the projectile in 69.2 MeV/u Biq+-Au collisions (77≤ q ≤ 82) measured at the GSI heavy ion synchrotron SIS18. These estimations proved to be in agreement with the values deduced from the charge exchange cross sections obtained from the target thickness dependent charge state distribution of the emerging ions. The Eikonal approximation indicates trends in consonance with the measured values and predictions according to Schlachter et al. are in reasonable agreement too.

Impact parameter dependent charge exchange studies with channeled heavy ions

We use decelerated (below 20 MeV/u) H-like heavy ions extracted from the GSI-ESR storage ring to study electron capture processes such as Radiative Electron Capture (REC) and Mechanical Electron Capture (MEC) in channeling conditions. With the help of simulations, we show that MEC occurs at relatively large impact parameters into highly excited states. REC studies provide information about the electron gas polarization.