Production of HO/sub 2/ within the track core in the heavy particle radiolysis of water

The molecular oxygen yield has been measured in the radiolysis of deaerated ferrous sulfate-cupric sulfate solutions irradiated with /sup 4/He, /sup 7/Li, /sup 9/Be, /sup 11/B and /sup 12/C ions. The initial ion energy was varied from a few MeV to about 30 MeV. The O/sub 2/ yield in this system can be taken as a measure of the HO/sub 2/ yield and for each particle is found to decrease rapidly with increasing ion energy. The differential HO/sub 2/ yield is found to vary from --0.25 with low energy carbon ions to --0.025 with the high energy helium ions; the latter is similar to the yield found with fast electrons. At a given LET the yield of HO/sub 2/ decreases with increasing particle Z. The authors conclude that HO/sub 2/ production primarily reflects the local density of energy deposition within the track core and not the partition of energy between the core and delta rays