Determination of Neutron-Induced Alpha-Particle Cross Sections on Carbon Using the Response of a Liquid Scintillation Detector

The sums of the cross sections ¹²C(n, α₀)⁹Be and ^I2C(n,n′3α) are determined in the neutron energy range between 7.4 and 11 MeV. An NE-213 scintillation detector is simultaneously used as a carbon target, an alpha-particle detector, and a neutron fluence monitor. By comparing the measured and calculated response spectra, the neutron-induced alpha-particle events in the scintillation volume are separated and the cross sections σ_n,α0 + σ_n,n′3α are determined relative to the n-p scattering cross section. The pulse-height distribution due to alpha particles allows the angular distribution to be extracted on the basis of the reaction kinematics and an accurately determined light output function for alpha particles in the NE-213 detector.