no PRIMARY PROCESSES 



being, in favorable cases, as high as 10~^ to 10"^) just for atomic num- 

 bers in the region near C, N, and : for larger Z the probability of K 

 excitation is very small, and also the probability of x-ray emission com- 

 petes more favorably with the Auger process. 



Summary 



The primary processes in the absorption of high-energy radiations by 

 matter are considered in relation to the chemical and biological effects 

 of the radiations. The importance of achieving a detailed understanding 

 of these processes is discussed, and the reasons for the extreme com- 

 plexity of the problem analyzed. Although simple isolated excitation 

 and ionization events are the preponderant primary process, the pos- 

 sibiHty of greater chemical effectiveness, especially in complex molecules, 

 of rarer events — particularly those involving greater-than-average en- 

 ergy transfer — suggests examination of less probable primary processes. 

 Several relatively infrequent processes are, therefore, investigated. Of 

 these, the nuclear collision may well be of chemical consequence in some 

 cases; direct multiple excitation or ionization is probably unimportant; 

 capture-and-loss of an electron is certainly unimportant as a distinct 

 process, although it may well influence the partition of the energy loss 

 between excitation and ionization; ejection by a swiftly moving charged 

 particle of an inner atomic electron, followed by Auger "disruption" 

 of the molecule, is a process, in effect one involving a great energy 

 transfer, which is distinct from great energy transfer to a secondary 

 electron, and, although no specific apphcation is offered, it is concluded 

 that this process might in some instances play a significant role. The 

 results of detailed calculations of the extent of some of these processes 

 in a typical case of interest (protons penetrating water) are presented. 



