Analysis of rotational coupling in collisions of Li+ with Ne leading to double excitation of Ne \ud

Electron angular distributions due to autoionization of Ne, doubly excited to the (2p43s2)1D state in collisions with Li+ in the energy range 1.2-2.2 keV, are measured in coincidence with Li+ scattered into a well defined direction ( Phi =0 degrees , Theta cm=10.8 degrees ). The experimental findings are analysed with the help of a collision model proposed earlier. In this model the initial excitation occurs by radial diabatic coupling to a molecular Sigma -state at small distances, followed by rotational coupling to Pi - and Delta -states at intermediate distances in the second half of the collision. The energy splitting between the Sigma -, Pi - and Delta -states is described by a model function. By adapting two parameters of this model function, the experimental findings can be reproduced within the experimental error in numerical calculations involving the relevant set of coupled differential equations. \u

Measurement of the H(n=2) density matrix for 20–100-keV collisions of H+ on He

Density matrices are experimentally determined which describe H(n=2) atoms produced in electron-transfer collisions between 20-100-keV protons and helium. The density matrix contains the electron-transfer cross sections σ2s, σ2p0, and σ2p+/-1, as well as the real and imaginary parts of the s0p0 coherence. Experimentally, a monoenergetic proton beam traverses a helium gas cell producing hydrogen atoms H(n) via electron transfer. Within the gas cell an electric field is applied either axial or transverse to the proton beam. The Stokes parameters describing the intensity and linear polarization of Lyman-α radiation (122 nm) emitted by H(n=2) atoms are determined as a function of applied electric-field strength. The density-matrix elements are determined from a linear least-squares fit of the Stokes parameters to the set of five fitting functions which represent the contributions from individual density-matrix elements. The density-matrix results are self-consistent. Separate determinations using axial or transverse electric fields agree with each other. The general results indicate σ2s>σ2p0>σ2p+/-1 between 20 and 100 keV. The electric dipole moment z has a value near zero at 20 keV rising to a maximum of about 1.3 a.u. near 40 keV and remaining nearly constant through 100 keV. The z,s moment has a maximum of about 0.5 a.u. at 25 keV, passing through zero near 70 keV. These results compare favorably with available experimental results and are qualitatively predicted by present theoretical models. Comparison with previous H(n=3) results indicates that the Runge-Lenz vector z is larger for n=3 than for n=2 and that z,s has the same values for both n

Measurement of the H(n=2) density matrix for 20–100-keV collisions of H+ on He

Density matrices are experimentally determined which describe H(n=2) atoms produced in electron-transfer collisions between 20-100-keV protons and helium. The density matrix contains the electron-transfer cross sections σ2s, σ2p0, and σ2p+/-1, as well as the real and imaginary parts of the s0p0 coherence. Experimentally, a monoenergetic proton beam traverses a helium gas cell producing hydrogen atoms H(n) via electron transfer. Within the gas cell an electric field is applied either axial or transverse to the proton beam. The Stokes parameters describing the intensity and linear polarization of Lyman-α radiation (122 nm) emitted by H(n=2) atoms are determined as a function of applied electric-field strength. The density-matrix elements are determined from a linear least-squares fit of the Stokes parameters to the set of five fitting functions which represent the contributions from individual density-matrix elements. The density-matrix results are self-consistent. Separate determinations using axial or transverse electric fields agree with each other. The general results indicate σ2s>σ2p0>σ2p+/-1 between 20 and 100 keV. The electric dipole moment z has a value near zero at 20 keV rising to a maximum of about 1.3 a.u. near 40 keV and remaining nearly constant through 100 keV. The z,s moment has a maximum of about 0.5 a.u. at 25 keV, passing through zero near 70 keV. These results compare favorably with available experimental results and are qualitatively predicted by present theoretical models. Comparison with previous H(n=3) results indicates that the Runge-Lenz vector z is larger for n=3 than for n=2 and that z,s has the same values for both n

Optical oscillator strengths of noble-gas resonance transitions in the vacuum-ultraviolet region

We report the results of an accurate measurement of the optical oscillator strengths of the prominent resonance lines of He, Ne, Ar, and Kr in the vacuum-ultraviolet region based on the absorption of resonance radiation. The transmission of this radiation through a layer of gas of finite thickness is measured as a function of the number density of the gas. The transmission function is fitted to this data to obtain the absorption oscillator strength. The accuracy of the present measurements ranges from 2.5% to 4%. The results are as follows: He i (58.4 nm), 0.2683±0.0075 (2.8%); He i (5.37 nm), 0.0717±0.0024 (3.4%); Ne i (74.4 nm), 0.010 17±0.000 30 (2.9%); Ne i (73.6 nm), 0.1369±0.0035 (2.6%); Ar i (106.7 nm), 0.0616±0.0021 (3.4%); Ar i (104.8 nm), 0.2297±0.0093 (4.0%); Kr i (123.6 nm), 0.1751±0.0049 (2.8%); Kr i (116.5 nm), 0.1496±0.0038 (2.5%)

Experimental determination of the H(n=3) density matrix for 80-keV H+ on He

The density matrix is determined for H(n=3) atoms produced in axially symmetric electron-transfer collisions of 80-keV protons on helium. In the experiment axial or transverse electric fields with respect to the proton beam are applied to the collision region. The intensity and polarization of Balmer-α radiation emitted by the H(n=3) atoms are measured as a function of the strength of the external electric field. Detailed analysis of the measured optical signals, taking into account the time evolution of the H(n=3) atoms in the applied electric field, makes it possible to extract the complete density matrix of the H(n=3) atoms at the moment of their formation, averaged over all impact parameters. Significant improvements in the experimental technique and in the data analysis associated with the fit of the density matrix to the optical signals have eliminated systematic effects that were present in our previous work [Phys. Rev. A 33, 276 (1986)]. The improvements in the apparatus are as follows: application of electric fields using electrodes with a simple geometry for the axial and transverse orientations that allows accurate calculation of the spatial variation of the electric field inside the collision chamber; use of high-quality optical elements and a rotatable, single-unit design for the polarimeter; automated gas handling for background subtraction; and full computer control of the electric fields, polarimeter, gas handling, and data acquisition. The analysis incorporates the following improvements: hyperfine structure of the H(n=3) manifold; cascade from the H(n=4) manifold; nonuniform detection efficiency over the viewing region; and modeling of the nonuniform electric fields, the nonuniform gas density, and the exponential decrease of the proton beam current in the gas cell due to electron transfer. With these improvements the results from axial electric field measurements are in good agreement with results obtained independently from transverse electric fields. Moreover, the extracted density-matrix elements are found to be within their physically meaningful bounds. The major results from 80-keV collisions are that the H(n=3) density matrix has an average coherence of 81%±1%, an electric dipole moment of 3.50±0.09 a.u., and a first-order moment of the electron current density distribution 〈(L×A)z,s〉 of -0.13±0.02 a.u. Results from a recent calculation show qualitative agreement with the experiment

Mixed configuration-interaction and many-body perturbation theory calculations of energies and oscillator strengths of J=1 odd states of neon

Ab-initio theory is developed for energies of J=1 particle-hole states of neutral neon and for oscillator strengths of transitions from such states to the J=0 ground state. Hole energies of low-Z neonlike ions are evaluated.Comment: 5 pages, 1 figure, 4 table

PORTEC-4a: International randomized trial of molecular profile-based adjuvant treatment for women with high-intermediate risk endometrial cancer

Background Vaginal brachytherapy is currently recommended as adjuvant treatment in patients with highintermediate risk endometrial cancer to maximize local control and has only mild side effects and no or limited impact on quality of life. However, there is still considerable overtreatment and also some undertreatment, which may be reduced by tailoring adjuvant treatment to the patients’ risk of recurrence based on molecular tumor characteristics. Primary objectives To compare the rates of vaginal recurrence in women with high-intermediate risk endometrial cancer, treated after surgery with molecularintegrated risk profile-based recommendations for either observation, vaginal brachytherapy or external pelvic beam radiotherapy or with standard adjuvant vaginal brachytherapy Study hypothesis Adjuvant treatment based on a molecular-integrated risk profile provides similar local control and recurrence-free survival as current standard adjuvant brachytherapy in patients with high-intermediate risk endometrial cancer, while sparing many patients the morbidity of adjuvant t

Determination of oscillator strengths from the self-absorption of resonance radiation in rare gases—II. Neon and argon

A previously developed method, based on the self-absorption of resonance radiation, is used to derive oscillator strengths for fourteen resonance transitions of neon and argon. Electron beam excitation of the atoms is used to produce the resonance radiation, which is partly absorbed in the gas between the beam and the spectrometer. A v.u.v. spectrometer is employed to record the radiation intensities as a function of gas pressure. Oscillator strengths are derived from the measurements by using a simple formalism. The influence of recoil effects (as a consequence of the excitation process) on the shape of the spectral emission lines and thereby on the transmission is checked by detailed numerical calculations. Special attention is paid to the determination of the quantities relevant in absorption measurements, i.e. the temperature, the absorption length and the number density of the atoms. The oscillator strengths obtained are compared with results from other experiments of various types (particularly forward inelastic electron scattering, for which on the whole good agreement with the present results exists) and from theoretical calculations

Determination of oscillator strengths from the self-absorption of resonance radiation in rare gases—II. Neon and argon

A previously developed method, based on the self-absorption of resonance radiation, is used to derive oscillator strengths for fourteen resonance transitions of neon and argon. Electron beam excitation of the atoms is used to produce the resonance radiation, which is partly absorbed in the gas between the beam and the spectrometer. A v.u.v. spectrometer is employed to record the radiation intensities as a function of gas pressure. Oscillator strengths are derived from the measurements by using a simple formalism. The influence of recoil effects (as a consequence of the excitation process) on the shape of the spectral emission lines and thereby on the transmission is checked by detailed numerical calculations. Special attention is paid to the determination of the quantities relevant in absorption measurements, i.e. the temperature, the absorption length and the number density of the atoms. The oscillator strengths obtained are compared with results from other experiments of various types (particularly forward inelastic electron scattering, for which on the whole good agreement with the present results exists) and from theoretical calculations