Dosimetry and measured differential W values of air for heavy ions.
Heavy-ion irradiation systems were designed and constructed at two cyclotron facilities in Japan for use in various fields of radiation physics and radiation biology. A 135 MeV/u carbon beam as well as 12 MeV/u carbon and helium-3 beams were first used in experiments. We have established a systematic method for heavy-ion dosimetry at both high and low incident energies involving measurements of fluences. We also obtained differential W values (w) of air for those beams by comparing the results of fluence measurement dosimetry with ionization chamber dosimetry. The differential W values of air were found to be 36.2 +/- 1.0, 34.5 +/- 1.0, and 33.7 +/- 0.9 eV for 6.7 MeV/u carbon ions, 10.3 MeV/u 3He ions, and 129.4 MeV/u carbon ions, respectively. The w value for high-energy heavy ions approaches the W value for high-energy electron or photon beams. In ionization chamber dosimetry for a heavy-ion beam, we found a track-size effect. A difference in the track sizes of heavy ions in the gas and solid phases affected the output current of the ion chamber in the case of high-energy heavy ions.
Kanai
T
T
Division of Accelerator Research, National Institute of Radiological Sciences, Chiba, Japan.
Kohno
T
T
Minohara
S
S
Sudou
M
M
Takada
E
E
Soga
F
F
Kawachi
K
K
Fukumura
A
A
D002244:Carbon; D004735:Energy Transfer; D006371:Helium; D007477:Ions; D010315:Particle Accelerators; D011853:Radiobiology / Q000379:methods*; D011874:Radiometry / Q000379:methods*
D007477:Ions; D006371:Helium; D002244:Carbon