~~ function of energy is fairly steep in certain regions. The current best values of L-to-K ratios have been measured at Livermore; they saw the gamma rays and came up with a figure of 0.23. Thus, depending on what people use to correct their X-ray counts, they will multiple by 2-1/2 in one case, and by 1.23 in another, and come out with a factor of 2 difference on this basis alone. This is an example of some of the things that one is liable to get into. Col. Russell: I think you would agree, wouldn't you, Marv,that despite the complexities of units, decay scheme, and Tungsten 181, you should count the thing in such a way that it is completely comparable, laboratory to laboratory, after you have worked out your fudge factor. Dr. Kalkstein: Les Machta showed curves of dpm. then this problem wouldn't arise. factors are being used. You are talking about atoms. I think if the data had remained in cpm, Further, there is always going to be confusion unless one makes clear what If one laboratory compares atoms of Tungsten 185 and 181, the manner in which they arrive at values in atoms should be investigated initially and standardized. Col. Russell: The solution, of course, is to have some laboratory responsible for production of these nuclides. claim that they produced 2.0 x 10°° atoms. you get so many cpm. fusion in this area. Maybe they didnt. Say they They give you a sample which you measure and You then have a factor from belief of the 2 x 1023 atoms. I don't see any reason for con- You can get confused on decay factors when you get into fission products, because yields can vary from device to device for a given fission product; certainly fractionation plays a large role in how validly you can convert from cpm to atoms or fissions, even though you know the counting efficiency of a given assembly quite accurately. I think a greater emphasis on dealing with things which are time-independent, and on getting back to the fundamental data, as recorded by the tracer producer, would be a very good thing. For example, today some things are recorded in dpm per standard cubic meter and cpm per standard cubic foot. I prefer to talk in terms of fissions or atoms assignable to given events. Dr. Kalkstein: I think all you really want to ask for is that people be very explicit about what they have done and how they get their numbers. If you have this, then you can apply your pencil. Floor: Dr. Machta showed a table which indicated certain sensitivities of analysis. one dpm or perhaps one-half adpm. In most cases you can resolve Based on this, you need samples for various nuclides ranging from a few to a few thousand standard cubic feet if you are above 100, 000 feet. At 160, 000 feet the requirement would be 1000 times this, and you would need something like a few hundred thousand ambient cubic feet sample. Marv said that if you have an area as small as 100 square centimeters or perhaps a square meter you could do something with the sample collected. There is a lot of difference between 100 square centimeters and a square meter. If you 39