Influence of scattering α particle on time spectra in explosive detection

The resolution of time spectrum is an important factor to obtain the excellent prompt gamma spectrum in the explosive detection. In this paper, we consider the scattering of α particle in the D-T reaction chamber wall is the main reason to the resolution of time spectrum. A measured device of time spectra based on associated α particle technique was built. A cone-shaped α particle collimator was designed to restrain the gamma induced by the neutron which is correlated to the scattering α particle. Thus, the resolution of the time spectrum was improved. Measurements show that with and without the collimator, the resolutions of the time spectrum are 1.8 ns and 6.4 ns, respectively.