Sorry about the delay. This came up for me because we had a good sized Cf source to deal with recently. When given the numbers the point source equation was referenced. My first reaction was that the point source would underestimate the rate for neutron, my logic that neutron emissions fall off at a slower rate than do gammas. At very close distances, less that a foot or two, it was irrelevant,the rate was very high. But I began to think about distances in the range of fifeteen or twenty feet. The controls for the source should never allow it to be unshielded for enough length of time as to be a hazard so this is really just a what if practice. But you never know. Anyway I got to thinking about how the point source equation applies to similar curie and Mev gamma vs neutron sources, how the equation applies to gammas of different Mevs and how it applies to neutrons of different Mevs. Mixed sources get complicated as the above post indicates. I will do a bit more research. Thank you for your replies. I know that almost anything I ask will receive a reasonable answer from someone on this site. Almost anything. Well sometimes its reasonable.