The ²⁵²Cf(sf) Neutron Spectrum in the 5- to 20-MeV Energy Range

The ²⁵²Cf neutron spectrum is measured at high energies with a miniature ionization chamber and two different NE-213 neutron detectors. The gamma-ray background and the main cosmic background caused by muons were suppressed by applying efficient pulse-shape discrimination. On the basis of two-dimensional spectroscopy of the neutron time-of-flight and scintillation pulse height, the sliding bias method is used to minimize experimental uncertainties. The experimental data, corrected for several systematic influences, confirm earlier results that show negative deviations from a reference Maxwellian distribution with a 1.42-MeV spectrum “temperature” for neutron energies above 6 MeV. Experimental results of this work are compared with various statistical model approaches to the ²⁵²Cf(sf) neutron spectrum.