The differentiation between fission fragments and alpha particles by a Time Projection Chamber

Abstract

In order to measure the cross sections of major actinides with high precision, a Time Projection Chamber prototype named fTPC has been developed at Tsinghua University taking advantage of its ability of 3D particle track reconstruction and dE/dx measurement. One of the main sources of the uncertainties of fission cross sections measurement is the differentiation between fission fragments and alpha particles, because their energy distributions are overlapped in low energy range. In this study, using the spontaneous fission fragments and alpha particles of 252Cf source, the ability of the fTPC to differentiate these two kinds of particles is studied. Combined with simulation results, the uncertainty of cross section caused by the differentiation in fTPC is estimated, From 100 ug/cm2 to 500 ug/cm2 of the target thickness, the uncertainties are evaluated as: 0.078%, 0.17%, 0.25%, 0.33% and 0.41%. All of them are less than 1%, which makes the uncertainty of fission cross section less than 1% become possible.