a Geant4 Simulation of the response of liquid scintillator neutron Detector unit1 (nD1). As the test and study of single unit of neutron Detector array. It includes the source code of the first part simulation of my bachelor's thesis project: "Simulation of Detector Response for Neutron at High and Intermediate Energy (中高能中子的探测器响应模拟）", awarded Outstanding Academic Papers by Students (OAPS), at Tsinghua University in 2021. Fulltext thesis (in simplified Chinese) at this link.