STOPPING POWERS OF SOLIDS FOR AR-40 AND CA-40 IONS AT INTERMEDIATE ENERGIES (20-80 MEV/U)

The stopping powers of 11 solid media have been measured for 20-80 MeV/u Ar and 80 MeV/u Ca ions from the French GANIL accelerator. The energy measurements were made using the LISE magnetic spectrometer. The accuracy in stopping power determinations is of plus or minus 1-2%. Several charge state distributions for Ar ions exiting relatively thick targets of Be, Al, Au have also been determined. The stopping power data have been compared with semi-empirical values from the literature, and with a scaling relative to He ion stopping powers, assuming fully stripped ions inside the degraders. The best agreement is obtained with the values from Ziegler (Pregamon 1980) over the whole energy range; the tabulation of Hubert et al. (Ann. Phys. Fr. 5 supp. (1980)) leads to a fair agreement with the data for degraders heavier than C, but overestimates the stopping powers of Be and C by 10-15%; the simple scaling method gives results in agreement with all data above 40 MeV/u.