Observation of the Resonant Coherent Excitation of highly-CHARGED IONS in Crystals
Aula Seminari (LNF INFN)
Via Enrico Fermi, 40
The coherent excitation of the relativistic ions in the electrical field provided by the crystal-target can be an efficient method for atomic as well as for nuclear spectroscopy of the heavy, highly-charged ions with a resolution which is orders of magnitude better than what can be achieved by using modern, standard solid state photon detectors and is, in this respect, competitive to the crystal spectrometry.
Several experiments with beams of few-electron uranium and argon ions have been performed at GSI (Darmstadt) and HIMAC (Tokyo) facilities.
The sequential 1s → 2s → 3p atomic transition in projectile ions coherently exited in the field of a Si-crystal at channeling and non-channeling conditions was observed. Beam of highly-charged ions was sent through a 1 μm Si-crystal mounted on a high precision, 5-axis goniometer. The fine tuning of the resonant condition is done by changing the crystal orientation instead of changing the incoming ion energy which is extremely time-consuming in the case of synchrotrons. The resonant excitation was identified by measuring the survival fraction of the initial charge state and the x-ray yeild from the decay of the excited state of the ion as a function of the crystal orientation.