[1] Beijing Normal Univ, Key Lab Beam Technol & Mat Modificat, Minist Educ, Beijing 100875, Peoples R China
[2] Beijing Normal Univ, Coll Nucl Sci & Technol, Beijing 100875, Peoples R China
[3] Beijing Radiat Ctr, Beijing 100875, Peoples R China
[4] Ctr Dis Control & Prevent, Beijing 100013, Peoples R China