52 



BURTON: Was he talking about electrons from the secondary process or 

 the primary? 



MAGEE: He stated that he was talking about a specific event, which formed 

 only one electron. Isn't that what you were talking about? 



PLATZMAN: Yes. 



BURTON: That was an isolated thing he was talking about, and I did not 

 think he was tying it up to this geometrical picture that you have been develop- 

 ing. 



MAGEE: Well, I want to make this discussion concrete. As nearly as I can 

 tell, this is the only way to get this picture. There are no real calculations on 

 this parameter b25il50J£. 







POLLARD: 150 A would be the range of a delta ray, or something like that. 



BURTON: That is the way I get it. 



POLLARD: It is much too high. 



MAGEE: It won't apply. The picture we c were given yesterday was for an 

 isolated event. Dr. Platzman calculated 50 A. 



BURTON: For 10-volt electrons. 



PLATZMAN: To thermalization, not to capture. 



e 



BURTON: The 150 A distance is for delta rays, if I understand correctly. 



FANO: No, the delta ray is very short usually as compared to that. 



POLLARD: e How does the 150 A get to be that big? I will take 50 A but I 

 cannot see 150 A. 



MAGEE: I don't know that this has ever really been described in detail. 



BOAG: It comes from two sources: (A) measurements of the initial sepa- 

 ration of ion pairs in a gas, as seen in cloud chamber photographs (2), scaled 

 down in the ratio of the densities of water and gas, and (B) saturation measure- 

 ments in compressed gases interpreted by the Jaffe theory (3). Neither method 

 is direct, but both yield about 150 A. 



MAGEE: That is, as I said, what has been generally believed. 



PLATZMAN: I think it is more of a pious hope than a belief. 



FANO: It is a figure applying to gases reduced in proportion to density. 



MAGEE: At Notre Dame Samuel and I have been trying to embark on a 

 program in which we would get as much evidence from different points of view 

 as possible on this picture, and we have not invested a great deal of time or en- 

 ergy in this particular type of calculation. We would like first to rough-out the 

 whole picture and then sharpen it up where necessary. That is what I am going 

 to try to do today. 



