Absolute determination of T-d neutron yields by the associated particle method

T-d neutron yields have been determined with a high accuracy of about 1% by measuring the associated α-particles from the 3H(d,n)4He reaction using a 3H-Ti-Cu solid target at selected incident deuteron energies in the range 140-300 keV. Our results on the determination of the neutron yield as well as the neutron fluence rate at a certain position far from the neutron source point are presented. The T-d neutrons were produced by the 300 kV Cockcroft-Walton accelerator of Rikkyo University. We used a silicon p-i-n photodiode as an α-particle detector for the yield determination and a NE213 liquid scintillator (2 in. x 2 in.) or a counter telescope with a (CD2)n radiator as a neutron detector for the fluence rate determination. A collimator with a hole of different size (2, 3 or 4 mm in diameter) was placed in front of the α-particle detector to define precisely the solid angle. The n-γ discrimination of the NE213 neutron detector was completely performed. The results on the neutron yields obtained by both methods are compared and discussed. The time characteristics of the neutron detector have also been studied using both the associated α-particle detectors of the silicon photodiode and the NE102A thin (10 μm) scintillator, which were placed at 900 with respect to the deuteron beam direction. (orig.)