The dosimetry of irradiations of Chlamydomonas cells with high LET radiations from a van de Graaff accelerator

Physical aspects are described of the use of a van de Graaff accelerator for the irradiation of Chlamydomonas Reinhardtii cells with mono-energetic protons, deuterons and α-particles having LET's in the range 100 to 1300 Mev g^-1 cm². The beam was monitored by an ionization chamber, and a d.c. to pulse-rate converter enabled accurate doses to be delivered; formulae are derived relating the dose in the cells to the current from a guarded field ionization chamber used to calibrate the monitor chamber. A silicon diode was used to measure the particle energy spectrum.