Evaluation of excited nl-state distributions of fast exit ions after penetrating through solid foils. Part 2: Determination of the nl-state distribution fractions of exit ions

摘要

In Part 1 [T. Miyoshi, K. Noda, Y. Sato, H. Tawara, I.Yu. Tolstikhina, V.P. Shevelko, Nucl. Instr. and Meth. B, this issue] of our two reports, new experimental data on charge-state evolution F_q(D) and equilibrium fractions F_q~∞ were presented when 4.3 MeV/u projectile ions with the atomic number Z = 6-26 pass through carbon. Also, in this paper, a ten-charge-state model for equilibrium fractions F_q~∞ expressed in terms of the charge-changing cross sections was suggested. In the present work (Part 2), a new method is suggested to determine the nl-distributions N_q(nl) of exit ions with a charge q in the specific nl-states by solving the balance equations with all appropriate effective cross sections as coefficients. The F_q~∞ and N_q(nl) values are normalized so that ∑_qF_q~∞ = 1 and ∑_(nl)N_q(nl) = F_q~∞. The efficiency of the present method suggested is illustrated by example of Ar ions colliding with a carbon foil at projectile energy of E = 6.0 MeV/u. It is found that the exit argon beam comprises about 12% of argon ions in the excited states. This method can be used for evaluation of the excited-ion components in the exit ion beam when the charge equilibrium has been reached. Besides, in this work, extending the method described in [Miyoshi et al., this issue], evaluation of nl-state distributions of exit ions at energies E = 4-20 MeV/u is performed for the case of Ar + C foil collisions, therefore, allowing to observe the nl-state distributions in a wide energy range.