ALPHA~SENSITIVE CELLULOSE NITRATE TRACK DETECTORS: APPLICATIONS TO THE STUDY OF ENVIRONMENTAL CONTAMINATION R. W. Buddemeier University of Hawaii, Honolulu A. H. Biermann and C. Gatrousis Lawrence Livermore Laboratory--Livermore, CA ABSTRACT Kodak LR~-115 Type TI cellulose nitrate alpha track detection film was evaluated for its utility in environmental plutonium studies. It was found that with fast and simple etching and reading techniques, the film "detects" 60 to 90% of the incident alpha particles with energy less than 4 MeV; both precision and efficiency may be increased by careful control of procedures. When applied to previously analyzed soil samples from Enewetak Atoll, it was found that ball-milled and gross soil samples were both highly heterogeneous in Pu distribution, with most activity concentrated in discrete particles of various types and sizes. For a one-day exposure to soil or a similar "solid" surface, detection sensitivity (5 x background) is approximately 50 pCi/g of total alpha activity and increases linearly with increased exposure time. Track detection films of this type provide a rapid and inexpensive means of obtaining quantitative estimates of environmental sample activity, and have unique utility for methods evaluation and the investigation of activity distribution as a function of phase, particle size, or organ in a heterogeneous sample. INTRODUCTION Applications of solid-state track detectors in a wide variety of fields have expanded dramatically during the last two decades; a comprehensive review of the field as of mid-1973 is given by Fleischer et al. (1975). Although successful alpha-sensitive films (usually of cellulose nitrate or cellulose acetate) have found widespread application only during the present decade, their utility is by now well established. 593