Update README.md

Author: shenvitor

README.md

@@ -1,7 +1,13 @@
 # nDa
-A Geant4 Simulation of the response of liquid scintillator neutron Detector array (nDa).
+A Geant4 Simulation for 2D neutron imaging detector response of liquid scintillator neutron Detector array (nDa).
+
+The main branch are the simulation situations of a sphere target materials.
+The advanced branch are the simulation situations of block object target materials with hole(s).
+
 It includes the source code of the second 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）](http://reserves.lib.tsinghua.edu.cn/Search/BookDetail?bookId=b662cc38-045e-48fe-981b-249b4d0689b2&f=goodbooks)",
 awarded [Outstanding Academic Papers by Students (OAPS)](http://reserves.lib.tsinghua.edu.cn/zhuantibooks?topic=7.%E6%B8%85%E5%8D%8E%E5%A4%A7%E5%AD%A6%E7%BB%BC%E5%90%88%E8%AE%BA%E6%96%87%E8%AE%AD%E7%BB%83%E4%BC%98%E7%A7%80%E8%AE%BA%E6%96%87%EF%BC%882021%EF%BC%89),
 at Tsinghua University in 2021.
+
 Fulltext thesis (in simplified Chinese) at this [link](https://drive.google.com/file/d/1FqneqfreOrdy_-2YB3TWRQ6nbg1H-J5s/view?usp=sharing).
+