. Basic mechanisms in radiobiology II. physical and chemical aspects. proceedings of an informal conference held at Highland Park, Illinois, May 7-9, 1953. Radiobiology; Radiation Effects. 49 SIMPLE THEORY (GAUSSIAN) LANDAU THEORY htl EXPERIMENTAL POINTS. AVERAGE TOTAL ENERGY LOSS MAXIMUM ENERGY LOSS IN SINGLE COLLISION fH»4*Vf«rtl|.hriM|m(L_ 50 60 76 PULSE HEIGHT- ARBITRARY UNITS Fig. 1. (reproduced from Igo et. al. , Phys. Rev. 89, 879 (1953) ). Frequency distribution of energy losses of Mev protons traversing 3/4" proportional counter. Histogram of experimental points shows standa
. Basic mechanisms in radiobiology II. physical and chemical aspects. proceedings of an informal conference held at Highland Park, Illinois, May 7-9, 1953. Radiobiology; Radiation Effects. 49 SIMPLE THEORY (GAUSSIAN) LANDAU THEORY htl EXPERIMENTAL POINTS. AVERAGE TOTAL ENERGY LOSS MAXIMUM ENERGY LOSS IN SINGLE COLLISION fH»4*Vf«rtl|.hriM|m(L_ 50 60 76 PULSE HEIGHT- ARBITRARY UNITS Fig. 1. (reproduced from Igo et. al. , Phys. Rev. 89, 879 (1953) ). Frequency distribution of energy losses of Mev protons traversing 3/4" proportional counter. Histogram of experimental points shows standard deviation and chan- nel widths. The theoretical Landau distribution is computed from Symon. The dashed curve is a Gaussian distribution based on ion pair statistics. The ordi- nate is counts per pulse height interval. and that the work I mentioned was the first real experimental test. FANO: Small energy losses enter in the theory only through their contribu- tion to the stopping power; there is another correction which is called the Blunck-Leisegang correction which you can put in if you want to, but does not amount to much. POLLARD: The proportional counter is a very nasty test to use in this region. You are just above the ease of detection against noise if you use 500 ion pairs. When you get down below that it is very hard to use. That means you have to have high multiplication factors. Immediately there begins to be the question of where the particle goes through the counter, and all the other tnings that make it hard to work with begin to come in. So I would feel there would be additional experimental uncertainty that I personally would worry about. FANO: I thought the proportional counter with a few kilovolts had been used by lots of people. POLLARD: It is not easy. FANO: No, it is not easy, but there is all that work on tritium, especially by the Glasgow people. BURTON: Was a number of proportional counters operating simultaneously in this instance?. Please note that
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