ee PREFACE": Be -.. ne . ™ mo“This report isconcerned with the high-dispersion ‘spectral characteriatics of the devices “fired at Operation Ivy and the comparison of these characteristics with those of other nuclear explosions recorded in Operations Greenhouse, Buster-Jangle, and Tumbier-Snapper..All the work reported here was done at the request of the Los AlamosScientific Laboratory. (LASL) and under the supervision of the J-Division of that laboratory. At Greenhouse, the : Optics Division participation (which included the spectroscopic work) was part of the Naval . Research Laboratory (NRL) program headed by Wayne C. Hall of the Electricity Division. For the remaining operations, spectroacopic work has been part of the Optics Division commitment directly to LASL.. . The spectrographic observations were made at Greenhouse and Buster-Jangle by Joseph A. Curcio, who, with Louis F. Drummeter, was also responsible for. the original identification: of many of the spectral features which are common to nuclear explosions.= The observations and the preliminary data reduction at Tumbler-Snapper and Ivy were =, made by Carl A. Beck and John H. Campbell. . The data analysis reported here was done in collaboration with DorothyB. Buttrey, who: also aided materially in the assembling of the final text: .