SUESBeRSERACED. 0018933 In cases where the stratum is not well defined, sample collections . can be made from the top of the cloud provided this can be reached and followed by the sampling aircraft or from a location selected to minimize the feed-in offallout from higher altitudes, The theory of this technique has been discussed under section 1.2.4 and the sampling equipment is described in Chapter 2. The operation plan wzs to fly through the light and variable layer at several intervals between H #2 and H £ 24 hours with B57D aircraft equipped both with the coincident samplers and with wing tank particle collectors, The coincident samples were to be znalyzed for Kr88 and Mo?? to determine the fallout partition (see 1,2,4) and the wing tank samples for ten radionuclides to investigate fractionation with particle size, 1.3.4 Aircraft Sampling of Fallout, The fallout sampling p2rt of the program was intended to provide information supplementary to that obtzined from the rocket and aircraft cloud sampling experiments, WB-50 aircraft were scheduled to fly at an altitude of 1000 feet and to collect fall- cat at various times between H / 4 and H # 24 hours along heightlines which would correspond to the cloud level {ca 55, 000 feet} sampled by the B57D's, Since the cloud is an extended source of fallout, the term "height- line sampling", as used here, signifies the sampling of 2 band of mzterial centered on the gecmetrical height line and hzving a band width approxi-