remain on ilmer, with the large one being stored in the Rad-Safe arce. Sinee all stations are on land masses, access for installation prior to Brevo may be by boat. Recovery of records and reactivation of Stations will require helicopter flights. No courier or sample return flights are required. 3.3 idject Number: } 2.3 AFSWP Pro jeg pificer: Title: Neutron Flux and Spectrum Measurements Performing Agency: Mr. T. D. Hanscome Naval Research Laboratory 3.3.1 Objective ~ To document the fast neutron and thermal neutron flux as a function of distance for the various high yield devices to be tested. To extend measurements of spectrum distribution, particularly in the region below ‘the sulfur threshold by using nuclear emulsions to detect the fissions fragments from neptunium, uranium-238, and urapiearaend thorium detectors, all of ‘which have fission thresholds in the region of 1 MEV. Although the limite neutron flux data obtained for the IVY detonztions indicate little significance for neutron radiation relative to other effects from high yield.detonations, several considerations indicate the importance of neutron measurements. Neutron flux does ot scale simply with the KT equivalent of a device but both the flux and spectrum are very dependent on ‘the, details of mechanical design of a device. Knowledge of the neutrory‘flyx and spectrum is essential for thorough analysis of weapons effetts.For example, such knowledge is required for the interpretation of big dical effects of bomb 3.3.2 a a an radiation, Procedure :Fgust i i Gold and tantalum detectors will be usedf‘for thermal flux neasurenent and sulfur detectors (3 MEV hyestiold) for fast neutrons, using the techniques described in WT-524.the Pashbn threshold detectors (uranium-238, thorium, and neptunium) usell| for measurement of the flux in the region of 1 MEV will be calibrated against a known flux from a Van de Graaff neutron source target and exposed’ in the cavity of 4 cm and 8 cm wall lead spheres. A limited number of measure~ ments will be made on all shots at distances ranging from!.2500 to 5000 yd from zero. Stations will be spaced approximately 500“yd,.in a range With several stations in a given direction and with 1 or 24 stations in different directions for some events. The use o p39 detectors is contemplated. 1. i WT-524, Neutron FluxMeasurements, Operation TUMBLER-SNAPFER, 28