Stripping cross-sections for fast, low charge state ions

The n-body classical trajectory Monte Carlo method has been used to estimate the cross-sections for electron loss from fast, low charge state ions after collision with BeF2. The two ions investigated were 20 MeV/u (2.6 GeV) Xeq+ and 40 MeV/u (8.4 GeV) Biq+, q = 1-12. The systems were chosen because of their relevance to the HYLIFE-II scenario. Single and multiple electron loss cross-sections for up to 10 stripped electrons were computed for each ion charge state. Multiple electron loss accounts for up to 50% of the total cross-section for these low charge state systems. To simulate the charge state evolution of the ions in a reactor focusing chamber, the calculated cross-sections were incorporated into rate equations assuming a BeF2 target density of 5 x 10(13) molecules/cm(3). At a position 3 m into the reactor chamber, incident Xe (+) and Bi (+) charge states are reduced to less than 1% of the total flux with the dominant charge states being Xe8 + and Bi6 +, respectively. (C) 2001 Elsevier Science B.V. All rights reserved.