以大亞灣實驗之逆β衰變信號測量碳12之中子捕獲截面

Abstract

大亞灣反應爐微中子震盪實驗位於中國東南方，搜集來自於大亞灣核電廠與嶺澳核電廠的反微中子以測量微中子震盪混合角 θ13。大亞灣實驗一共設有八個液態閃爍體探測器，其中四個距離核電廠五百公尺遠，而另外四個距離兩公里遠，藉由不同距離的區別，將可以觀測到微中子震盪現象。在經歷了 1958 天的運轉後，大亞灣實驗合作組在 2018 年時發佈了最新的 sin2 2θ13 和 ∆m232 的量測結果。 在透過逆 β 衰變量測反微中子的實驗中，正子淹滅信號將會伴隨一個中子捕獲信號，而在大亞灣實驗中，主要的捕獲信號有三種，分別為中子-氫、中子-釓、中子-碳。本論文中將會以氫、釓作為比較基準以測量 12C (n, γ)13C 反應之截面，並將藉由逆 β 衰變產生之中子的測量結果與傳統核物理中的熱中子測量結果做比較並檢查一致性。

The Daya Bay reactor neutrino experiment was located in southeast of China to collect the antineutrinos from the reactors in nuclear power plants, Daya Bay and Ling Ao. For the purpose of measuring the neutrino mixing angle θ13, there were total eight liquid scintillator detectors, while four were 500 m away from plants and other four were about 2 km. With this discrepancy, the phenomenon of neutrino oscillation can be observed. In 2018, the Daya Bay collaboration published the latest result of sin2 2θ13 and ∆m232 with 1958 days operation. In antineutrino detection via inverse beta decay, a positron annihilation is followed by a neutron absorption signal. This signal can be used to measure the absorption cross section. In Daya Bay experiment, there are 3 kinds of neutron absorption event dominantly, which are neutron-hydrogen, neutron-gadolinium, and neutron-carbon. In this thesis, the hydrogen and gadolinium are treated as comparators to measure the cross sec- tion of 12C (n, γ)13C by inverse beta decay neutron to check the consistency with the one measured by traditional thermal neutron in nuclear physics.