contract the rubber hydrochloride to a smooth, taut surface, The backing and cover for the counting sample which were made of a very thin file of low atomic weight materials reduced self-absorption and backscattering of the beta rays to a minimum. On Shot 1 the beta counting eamples were prepared in glass planchete because of the large amount of solide, these samples were quite thick so that those beta decay data for Shot 1 were subject to considerable self-absorption of the soft componente , Gamma counting samples were prepared in glass planchets 1 in. od. from the same solutions as the beta sources, After drying, the sazple was coated lightly with Krylon. 5.1.2 Desay Beta and gamma decay measurements were taken of all fallout san- ples received and processed by the field laboratory for Shots 1 through 4, to check for gross fractionation in the fallout, The gross beta decay of the fallout samples from Shots 1 through 4 are given in Table 5.1 and are plotted in Fig. 5.1. The groes ganm decay data are given in Table 5.2, and are plotted in Fig. 5.2. The relative count in each case was normalized to the number given in parentheses at + 10 days. 5.1.2.1 Shot The gross bete and gamma decay data are average values of all the fallout samples received at the site laboratory (Chapter 3), In addition, some values for the gamma decay (later than 10 days) were obtained from Project 2.5a as an average decay of five active particles from gummed paper samples. 5ole2.2 Qhot The early gamma decay wes taken on a gummed paper collector exposed to fallout at Parry Island on shot day. Fallout arrived at about 1800 to 1830 hr or + 12 hr after shot time. The sample, consisting of a one sq ft folded paper did not prove suitable for beta decay measurements, The beta decay and gamma decay data from 3 days are an averaged decay of all the fallout samples received at the site laboratory. Dele2e3 Shot The beta decay date and the gamma data are averaged values of the decay of all the samples received at the site laboratory. 5ele2e4 Shot Beta decay was observed on a sample recovered aboard the YAG-39 (Project 6.4) at + 20 min. Gamma decay was started et +4.€ hr. Both decays were initially observed on a GM counter, Due to the high background, high-counting samples were required. A ganma ionization decay 101