Forbidden transitions in the helium atom

Nonrelativistically forbidden, single-photon transition rates between low lying states of the helium atom are rigorously derived within quantum electrodynamics theory. Equivalence of velocity and length gauges, including relativistic corrections is explicitly demonstrated. Numerical calculations of matrix elements are performed with the use of high precision variational wave functions and compared to former results.Comment: 11 pages, 1 figure, submitted to Phys. Rev.

Systematic study of the effect of short range correlations on the form factors and densities of s-p and s-d shell nuclei

Analytical expressions of the one- and two-body terms in the cluster expansion of the charge form factors and densities of the s-p and s-d shell nuclei with N=Z are derived. They depend on the harmonic oscillator parameter b and the parameter $\beta$ which originates from the Jastrow correlation function. These expressions are used for the systematic study of the effect of short range correlations on the form factors and densities and of the mass dependence of the parameters b and $\beta$. These parameters have been determined by fit to the experimental charge form factors. The inclusion of the correlations reproduces the experimental charge form factors at the high momentum transfers ($q\geq 2 1/fm$). It is found that while the parameter $\beta$ is almost constant for the closed shell nuclei, $^4$He, $^{16}$O and $^{40}$Ca, its values are larger (less correlated systems) for the open shell nuclei, indicating a shell effect in the closed shell nuclei.Comment: Latex, 21 pages, 6 figures, 1 tabl

Evaluation of a proximal tubule incubation system for the detection of nephrotoxicants

SIGLEAvailable from British Library Document Supply Centre-DSC:DXN018090 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

AUTOIONIZATION FOR LOWER-LEVEL DE-TRAPPING IN X-RAY LASERS

A novel type of x-ray laser is analyzed in which the population of the lower level is depleted by autoionization instead of spontaneous decay. The intention is to decrease radiative trapping effects that quench the gain and require microscopic plasmas. Two sample systems are described. Proof-of-principle atomic-physics experiments and numerical modeling are needed to verify feasibility, fluorescence and lasing

RECENT ADVANCES IN SOFT X-RAY LASER EXPERIMENTS USING GERMANIUM AND COPPER PLASMAS

Soft x-ray gain coefficients of 1.7-4.1 cm-1 are measured on eight lines in the wavelength range of 196 to 286 Å using 3p-3s transitions in neon-like Cu19+ and Ge22+ ions. The lasant plasma is created by a high-power laser line-focused onto thin-foi1 and solid-slab targets. Measured wavelengths agree with calculations. A previously-reported anomaly in gain for a J=0 upper level is small in these experiments

LASER-DRIVEN SOFT X-RAY LASING IN COPPER AND GERMANIUM PLASMAS

Soft x-ray lasing has been achieved for the first time on 3p-3s transitions in neon-like copper (Cul9+) and germanium (Ge22+). The elongated lasant plasma was produced using the NRL Pharos III laser operating at λ = 1.05 µm, 300-480 J with a pulse duration of 2 ns. Lasing was observed in the wavelength interval 196 to 286 Å for J = 2 → 1 and J = 0 → 1 lines, using both thin film and thick slab targets