Can multiple structures in positron spectra be caused by atomic effects?

In recent experiments at least two structures have been detected in positron spectra from subcritical (total chargeZ ≦ 174) heavy-ion collisions at bombarding energiesE _Lab=5.7?5.9 MeV/n. The origin of these structures is unexplained up to now. Atomic effects have already been discussed as a possible source in a previous paper, where a schematic ansatz for the electronic transition matrix elements was employed. Meanwhile numerical calculations forK-vacancy formation also exhibited oscillations in the impact parameter dependence when using this ansatz. In this paper we report on a scaling law describing these oscillations. As a consequence certain subsidiary conditions have to be imposed on our schematic ansatz, which in turn yield a new understanding on eligible atomic sources for multiple structures in the emission spectra of positrons.     

Coupled channel analysis of inner-shell vacancy formation in superheavy quasimolecules

We calculate the ionization probability of the quasimolecular 1sσ-state in collisions of very heavy ions with (Z ₁+Z ₂) α?1. Multistep excitation processes between bound and continuum states are investigated. Due to the multistep processes the number of created 1sσ-vacancies is typically increased by a factor 2–5 over that obtained within time-dependent perturbation theory (i.e. the one-step processes). Some implications of the many-electron problem and the Pauli principle are discussed. The δ-electron distribution is compared with recent experimental data.     

Theory of non-adiabatic cranking and nuclear collective motion

The cranking model is extended to the case of a general non-adiabatic motion. The time-dependent many-body Schrödinger equation is solved, where the time dependence of the collective motion is determined by the classical Lagrange equations of motion. The Lagrangian is obtained from the expectation value of the energy. In the case of one collective degree of freedom the condition that the expectation value of the energy is constant in time is sufficient to determine the collective motion. An iteration procedure is applied, of which the zeroth order is shown to be the common cranking formula. In an alternative approach the energy conservation is expressed in differential form. This leads in the case of one collective degree of freedom to a set of coupled, non-linear first-order differential equations in time for the expansion coefficients of the many-body wave function and for the collective variable. As an illustrative example we solve the case of two coupled linear harmonic oscillators.     

Synthese et caracteristiques spectrales de f-alkyl-2 dihydro-3, 4 oxo-4 quinazolines

In this paper, we report the preparation of a series of 4(3H) quinazolinones substituted in the 2 position by a linear perfluoroalkyl-chain with R_Fas C_n F_2n+1(n=1, 3, 5, 7).These compounds are obtained in two steps, action of F-acid chlorides on 2-aminobenzonitrile which affords the corresponding F-amides followed by cyclization of this intermediate with alkaline hydrogen peroxide. We isolated a reaction intermediate in the cyclization of N-(2-cyanophenyl) F-octanamide. All compounds were identified by the usual spectroscopic methods (IR, NMR¹H, ¹⁹F, mass spectrometry).     

Renormalized finite temperature effective potential ofSU(2) Yang-Mills theory

It is shown that the renormalized finite temperature effective potential for continuumSU(2) Yang-Mills theory develops a non-perturbative minimum for sufficiently strong coupling, i.e. below a critical temperature. The corresponding phase can be the candidate for the confining phase of the continuum theory and becomes energetically favoured basicly due to the decay of theA ⁰ condensate into three gluons.     

The influence of rotational coupling on K-vacancy formation in U-Pb collisions

The beta endpoint energies of the alkaline fission products^88–94Rb and^139–144Cs have been measured with an intrinsic Ge-detector at the OSTIS fission product separator. The linearity and high resolution of the detector yields an accuracy of up to a few keV. Additional beta gamma coincidence spectra allow the deduction of Q_β-values.     

The impact parameter dependence of the Pb + Pb K − MO spectrum

Molecular orbital X-rays are emitted during ion-atom collisions. The theoretical treatment, numerical results for the Pb + Pb system and a comparison with background radiation like NNB, SEB and γ-decay of Coulomb excited nuclei are presented.     

Conversion coefficient for internal pair creation

The conversion coefficient for internal electron-positron pair formation is calculated for arbitrary electric and magnetic multipolarity. Analytical expressions for the differential conversion coefficientdβ/dE _p can be derived in the range 0≦Z≦118, if one employs relativistic Coulomb wave functions according to pointlike nuclei for the electron. Especially forML-transitions in the high-Z-region we found large deviations from results obtained within the Born approximation.