Anomalous temperature reduction of electron cooled heavy ion beams in the storage ring ESR

Experiments with low intensity beams of electron cooled highly charged ions in the storage ring ESR have been performed. The momentum spread which was analyzed by Schottky noise detection shows a considerable reduction when the number of stored ions is reduced below several thousands. This indicates that intrabeam scattering which determines the momentum spread for higher beam intensities is strongly suppressed. Estimates of the plasma parameter #GAMMA# support the idea of a phase transition from a gaseous phase to a liquid like phase. (orig.)12 refs.Available from TIB Hannover: RO 801(96-45) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

First experiment with decelerated bare uranium ions conducted at the ESR storage ring

The deceleration capabilities of the ESR have been used for the first time in a dedicated ground state QED experiment conducted at the gasjet target of the ring. By decelerating bare uranium ions from 358 MeV/u down to energies of as low as 49 MeV/u, X-ray spectra have been obtained which provide an abundant yield of characteristic X-ray transitions. The experiment demonstrates that, by choosing the appropriate beam energy and gasjet target, almost all excited projectile states can be selectively populated. Moreover, the experiment provides the first data for beam lifetimes of stored decelerated high-Z ions. Such data are essential for the design of future experiments dealing with decelerated ion beams far below 50 MeV/u. (orig.)Available from TIB Hannover: RO 801(96-34) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekSIGLEDEGerman

Charge-exchange cross sections and beam lifetimes for stored and decelerated bare uranium ions

Charge-exchange cross sections and beam lifetimes are studied for decelerated bare uranium ions at the ESR storage ring. By deceleration from the initial energy of 358 MeV/u down to various energies as low as 49 MeV/u, i.e. far below the production energy of bare ionic species, the electron pick-up cross sections were obtained for collisions with N_2, Ar, CH_4 and Kr gaseous targets. The measured cross sections and beam lifetimes are compared with the theoretical results for radiative and non-radiative electron capture. The present data along with the theoretical approximations discussed, provide a solid basis for the estimation of beam lifetimes for decelerated bare high-Z ions. Moreover, a normalization procedure is proposed, in which absolute total charge-exchange cross sections are derived by normalizing the simultaneously measured yield of K-REC photons to rigorously calculated relativistic cross sections. This method along with the unprecedented beam conditions at the ESR storage ring, allows a significant improvement in the accuracy of cross section data. (orig.)SIGLEAvailable from TIB Hannover: RO 801(98-42) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman