Inactivation of Ribonuclease by Elastic Nuclear Collisions

Abstract

The primary cosmic rays consist of rapidly moving atomic nuclei. Besides the very frequent protons, the nuclei of heavier elements have also been detected. These highly charged particles interact with matter in a variety of ways. The atoms and molecules in the vicinity of the particle track experience an electrostatic force by which electronic quantum transitions are induced. Consequently excited and ionized atoms and molecules are the most frequent primary products in the first stage of radiation action. In additions to these two dominant primary processes there are other ways by which the incident particle may dissipate its energy. The most important of these are nuclear reactions and elastic nuclear collisions. While the biological consequences of excitations and ionizations have been widely investigated in photobiology and radiation biology, not much work has been done on the biological effects of nuclear reactions, and no one has succeeded in demonstrating convincingly the biological effectiveness of elastic nuclear collisions. If energy is transferred to an atom or molecule by one of the latter mechanisms, a much more violent disturbance is caused than would be caused by an excitation or ionization. Thus it might turn out that elastic nuclear collisions cause biological damage with higher effectiveness than excitations and ionizations do, especially in very large and stable molecules and in biological structures, which may recover from excitations and ionizations. Therefore it appeared necessary and interesting to investigate the biological effectiveness of mechanisms other than excitations and ionizations.