Neutron spectra were measured with proton-recoil proportional counters at various locations in a high flux irradiation cell used for biological investigations. The energy range of the measurements is from 1 keV to 2 MeV. Rate-of-pulse-rise information was used to distinguish proton recoils from gamma-ray induced fast electron events. The proton-recoil distributions were corrected for various inherent distortions such as those resulting from the deviation of the electric field in the counter from infinite coaxial-cylinder values. Systematic variations are noted in the shape and magnitude of the neutron spectra as a function of cell position. The influence on the spectra of having specimens present in the room is shown. The neutron spectrum near the center of the cell is compared with a calculated spectrum based on a one-dimensional model of the cell. The discrete-ordinate transport equations were solved using a multienergy-group cross-section set.

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