ATOMIC CHARGE STATES IN CARBON OF 10- TO 40-MEV IONS; APPLICATION TO TANDEM ACCELERATORS

The distribution of charge states of ions of F19, Cl35, and Br79 emerging from thin carbon foils at energies of 10 to 40 Mev have been measured. Atomic charges of 7, 9, and 11 electron units for the three elements respectively are produced at 10 Mev with an intensity of greater than 15% of the incident beam. These results show that a tandem accelerator with 10 Mv on the terminal can deliver good ion beams at the following energies (the values in parentheses require two-stage stripping resulting in a further reduction in beam intensity by a factor of 5 to 10): 80 Mev (95 Mev) F19 ions, 100 Mev (125 Mev) Cl35 ions, and 120 Mev (160 Mev) Br79 ions. The measurements show that heavy ions from a tandem accelerator can be injected into a cyclotron and stripped to give appropriate magnetic rigidity for acceleration to very high energies; for example, a 90-in. diameter magnet with a field of 14 kilogauss will yield Cl or Br ions.