Studies on Vicia faba root meristems irradiated with a pion beam.

Abstract

in the tumor region might overcome some of the radioresistance of an anoxic tumor. The most useful beam available at the cyclotron for our purpose is a 90-MeV tr- beam. At this energy the intensity of the pion beam is a maximum and the background is not excessive. The range of these pions is around 25 cm of tissue, which is excessive for the therapeutic applications. In studying the effects of the stopping pions, therefore, an appreciable amount of Lucite absorber must be used, which not only attenuates the beam but also produces loss by divergence of the beam. These factors must be considered in irradiating biological materials. The dosimetry of this radiation presents a number of new problems that have not been entirely solved. Among these, at present, is the fact that the background radiation, consisting of electrons and muons in the beam, amounts to about 40% of the total number of particles in the beam. In spite of the questions that remain to be answered, it is nevertheless useful to