The influence of ambipolarity on plasma confinement and the performace of ECRIS

International audienceCharge diffusion in an ECRIS discharge is usually characterized by non ambipolar behavior. While the ions are transported to the radial walls, electrons are lost axially from the magnetic trap. Global neutrality is maintained via compensating currents in the conducting walls of the vacuum chamber. It is assumed that this behavior reduces the ion breeding times compared to a truly ambipolar plasma. We have carried out a series of dedicated experiments in which the ambipolarity of the ECRIS plasma was influenced by inserting special metal-dielectric structures (MD layers) into the plasma chamber of the Frankfurt 14GHz ECRIS. The measurements demonstrate the positive influence on the source performance when the ECR plasma is changed towards more ambipolar behavior

Influence of damping on the excitation of the double giant resonance

We study the effect of the spreading widths on the excitation probabilities of the double giant dipole resonance. We solve the coupled-channels equations for the excitation of the giant dipole resonance and the double giant dipole resonance. Taking Pb+Pb collisions as example, we study the resulting effect on the excitation amplitudes, and cross sections as a function of the width of the states and of the bombarding energy.Comment: 8 pages, 3 figures, corrected typo

Excess in Nuclear e^{+}e^{-} Pairs near 9 MeV/c^{2} Invariant Mass

Data on internal pair conversion in widely different nuclear transitions with energies above 12 MeV have an apparent excess in e(+)e(-) pairs around 9 MeV/c(2) invariant mass. While the deviations individually may be circumstantial, in combination they appear to point to an overall anomaly