Cyclotron-produced protons of nearly monoenergetic initial energy of 6.94 MeV are degraded to 4.9 MeV at sample position by passing through aluminum foil, polyester film beween vacuum and air, ionization chamber and air. The irradiation system for 23 MeV alpha-particles is essentially the sase as that for protons except for the acceleration of alpha-particles.
The electromagnet was set up so that the magnet field direction was parellel to the proton beam. The intensity of magnetic flux density was determined by a gauss meter (Maezumi MG-330DS). The intensity at sample position is about 1.1 Tesla.
Leukocytes spread into nearly monolayer (confirmed under discetion microscope) were covered by 5-microm thick polycarbonate film, and irradiated (see: cell preparation).
Dose calibration: The dose to the cell surface was determined according to the stopping power of water provided by Bethe (1983, 1984).
Bethe HA. (1983) Handbuch der Physik, 24(1), pp.273-560, Springer, Berlin.
Bethe HA and Heitler W (1984), Proc Roy Soc A146:83-112.
