HIF 2010
18th International Symposium
on Heavy Ion Inertial Fusion -
Information

Title:	Dr.
Family Name:	Rzadkiewicz
First Name:	Jacek
E-Mail:	j.rzadkiewiczipj.gov.pl
Affiliation for Badge:	IPPLM
Institute:	IPPLM
Address (Street):	Hery 23
Postal Code, City:	01-497 Warszawa
Country:	Poland
Phone:	+48 22 638 10 05
Fax:
Payment:	Cash at the conference site
Author(s):	J. Rzadkiewicz A. Gojska, O. Rosmej, M. Polasik, and K. Słabkowska
Institute(s):	The Andrzej Soltan Institute for Nuclear Studies, PL-05-400 Swierk, Poland Institute of Plasma Physics and Laser Microfusion, Hery 23, PL-01-497 Warsaw, Poland Gesellschaft fur Schwerionenforschung mbH, Plasma Physik, Darmstadt, Germany Faculty of Chemistry, Nicholas Copernicus University, PL-87-100 Torun, Poland
Title:	Interpretation of the Si Kα x-ray spectra accompanying the stopping of swift Ca ions in low-density SiO2 aerogel
Abstract:	We present a detailed analysis of the Kα x-ray spectra of Si induced by 11.4 MeV/u Ca projectiles penetrating a low-density SiO2 aerogel target measured with high spectral and spatial resolution at the UNILAC accelerator at GSI-Darmstadt. The low-density material used in the experiment was crucial for the space-resolved studies of the Si x-ray radiation (for different energies of stopping Ca ions). The stopping length of the 11 MeV/u Ca ions reaches up to 10 mm in the low-density SiO2 aerogel, whereas in regular quartz solid targets it is about 100 times shorter. The analysis of the x-ray spectra emitted by the stopping medium has shown a high level of the L-shell ionization, especially in the later considered phase (Ep ∼ 5 MeV/u) of the stopping process. It has been further demonstrated that the population of the highly ionized states produced in the ion-atom collisions can be substantially reduced in the time between the collision and the x-ray emission due to the very intense rearrangement processes occurring in Si situated in the chemical environment of oxygen atoms. Moreover, comparison of the experimental values of the Kα L-shell satellite energy shifts with the results of the multiconfiguration Dirac-Fock calculations allows us to find that Si valence electron configuration is enriched due to electron transfer from valence-electron-rich oxygen atoms into highly ionized silicon atoms. Our results indicate that the Coulomb explosion in a highly ionized track core is prevented by rapid neutralization in the femtosecond time scale.
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