through an inclusive analysis of the entire weapon use operation, To base a production program on the nebulous argument given as to military oe acceptability would be quite wrong. | Dr, Rabi inquired from Dr. von Neumann as to the adequacy of the _ theory of preinitiation. The latter replied that it stands intermediate between the theory of criticality, which is in very good shape, andthe theory of yield, The theory of yield is good only to about a factor of two without onpirical corrections based on data from the shots which have been fired; with these corrections it gives accurate results, Dr, Rabi said that it is the early stages of neutron multiplication which are not wellunderstood; these are crucial in the preinitiation problem, He also said that a good theory of the thermonuclear weapon is not available either, and furthermore that it is not well established what would be the difference in weapon effects between, for example , 3 megatons and 7 megatons. | | oe ‘The summaryof Dr, Froman's letter in AEC 374/8 stated, inpart, that . there is no significant evidence from tests that preinitiation theory3is incorrect and that there is a very good basis for believing the predictions | of preinitiation probability. Dr, Froman's analysis gave the result that in thirty three tests the calculated probability that preinitiation would have escaped detection (as it did) is 0.42. The Secretary pointed out. _ that. while this result shows that the shot results are consistent with preinitiation theory, they cannot be taken as quantitative confirmation of theory,: For example, the fact that no preinitiation was observed is < yo Eva Sim any os ergy SE 8 aml the 33 shots, 5 Neven more consistent! with zero probability of preinitiation in each of |

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