NEUTRON AND GAMMA-RAY SPECTRA FROM TH-232, U-235, U-238, AND PU-239 AFTER BOMBARDMENT WITH 14-MEV NEUTRONS

The neutron and gamma-ray leakage spectra from pulsed spheres having a radius equal to 1. 0 mean-free-path (mfp) for 14-MeV neutrons in **2**3**2Th, **2**3**5U (with radii of 0. 7 and 1. 5 mfp), **2**3**8U (with radii of 0. 8 and 2. 8 mfp), and **2**3**9Pu (with radii of 0. 7 and 1. 25 mfp) were measured by using time-of-flight techniques. The neutron spectra were measured between 0. 9 and 15 MeV using stilbene and NE-213 scintillators. For the gamma rays, the electron recoil spectra were measured between 0. 35 and 8 MeV with the NE-213 detector only. Pulse-shape discrimination and flight paths of similar 10 m were used in these measurements. The measured spectra are compared with calculations carried out with TARTNP, a coupled neutron-photon Monte Carlo transport code. To facilitate the use of the neutron data for calculational purposes by other laboratories, an ″experimental″ one-dimensional neutron energy spectrum is given for each measurement.