Average energy to produce an ion pair (W̄), distance restricted, and total linear energy transfer and dose as a function of radial distance D(r) from the ion's path were measured for 41.1-MeV16 O ions in nitrogen and Rossi-type tissue-equivalent gas Results for W̄ were 38.9 ± 0.54 eV/ion pair for nitrogen and 33.4 ± 0.47 eV/ion pair for tissue-equivalent gas. Results for total linear energy transfer (<tex-math>${\rm LET}_{\infty}$</tex-math>) were <tex-math>$6507\ {\rm MeV}\cdot {\rm cm}^{2}\ {\rm g}^{-1}$</tex-math> for tissue-equivalent gas and <tex-math>$6210\ {\rm MeV}\cdot {\rm cm}^{2}\ {\rm g}^{-1}$</tex-math> for nitrogen. Results for D(r) were used to calculate similar values to be expected in tissue-like material having a density of <tex-math>$1\ {\rm g}/{\rm cm}^{3}$</tex-math>. The range of radial distances covered was from 0.2 to 300 nm in tissue. Results are compared with calculations based on Paretzke's continuous slowing down model. Measured D(r) values in nitrogen were randomly distributed about the calculated values between radial distances of 0.56 and 286 nm. The mean deviation between the experimental and the calculated value was 1.3% (the experimental value being higher). For tissue-equivalent gas, previously measured D(r) values were also randomly distributed about the calculated values, with a mean deviation of 4% (the experimental value being lower) between radial distances of 1.5 and 140 nm.

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