| et ' of Eq. 2 requires contour maps of m and I(t) for the whole fallout area. In the ideal case, Mp would be essentially equal to the mass of material removed from the crater. 3.3 DEFINITION OF THE FRACTION OF DEVICE CONTOUR RATIO | The fraction of the device contour ratio at any point in ye fall- out area is défined by ~ D FD, (+) = atte) (3) in which a is the radioactivity (or measure of it) per unit area and an is the total radioactivity (or measure of it) produced by the device. The ratio, a/ap is the fraction of the device per unit area and can be defined and measured in many ways. One fairly common of the activity is in terms of the number of fissions activity from the fission process. The advantages of are that its value is independent of time and that it determining weapon yields. The disadvantage of using unit of measure for the radiousing this unit is also used in the unit is that it is quite often related to a single fission product tracer nuclide and its fission yield, and is not a reliable measure of the true number of fissions in a given sample of fallout when the radionuclides are fractionated. Excepting for fractionation or alteration of the radionuclide composition at various points in the fallout area from that produced by the device, the fraction of the device contour ratio for an extended plane surface should be a grand average function. Even with the occurrence of fractionation, the point variation. of this contour ratio will not be large for areas where the pattern of fractionation is the same. Other parameters that effect the value of this contour are discussed in some of the following sections. 3.4 HE IDEALIZED CONTOUR RATIO SCALING FUNCTIONS — por/NY rey Ac f ce) 10 es) It For the idealized model function, it will be assumed that, in the detonation, induced (neutron capture) radionuclides are produced as well