The high precision measurement of 208^{208}Pb+208^{208}Pb Mott scattering at energies under the Coulomb barrier: the observation of new atomic effects

International audienc

The high precision measurement of 208^{208}Pb+208^{208}Pb Mott scattering at energies under the Coulomb barrier: the observation of new atomic effects

International audienc

Atomic Effects on Heavy-Ion Scattering

Angular distributions of a Pb-208 beam on Pb-208 thin targets at very small angles were measured. The shape of the experimental distribution is not Gaussian, indicating a plural scattering regime rather than multiple scattering. The distribution was well reproduced by a Monte Carlo simulation of the straggling process. For the first time we observed and quantified the influence of the production of electrons during the scattering. This effect was observed in the angular correlation of the scattered Pb-208 nuclei detected in kinematic coincidence and also in the limiting angle of the Pb-208 scattered in a Ag-107,Ag-109 target. This effect introduces a spread in the scattered angle which is of the same order of magnitude as the angular straggling.</p

Atomic effects in heavy-ion elastic scattering

International audienc

Search for color van der Waals force in 208^{208}Pb+208^{208}Pb Mott scattering

In a high precision experiment, Mott scattering of the 208Pb+108Pb system was measured at Elab=873.40 MeV and 1129.74 MeV with kinematic coincidences for angle pairs around θlab=30°, 60° and θlab=45°, 45°. The observed Mott oscillations exhibit an angular shift with respect to pure Mott scattering. A comparison with the angular shift produced by a color van der Waals force including nuclear polarizability, vacuum polarization, relativistic effects, and electronic screening provides a new upper limit for the strength of this force. Influence of atomic effects other than screening were identified for the first time

Atomic effects in heavy-ion elastic scattering

International audienc