Determination of the Gamma-Ray Spectrum in a Strong Neutron/Gamma-Ray Mixed Field

The knowledge of gamma-ray spectrum highly affects the accuracy of the correspondingly derived gamma-ray dose and the correctness of calculated neutron dose in the neutron/gamma-ray mixed field dosimetry when using the paired ionization chambers technique. It is of our interest to develop a method to determine the gamma-ray spectrum in a strong neutron/gamma-ray mixed field. The current type detector, Mg(Ar) ionization chamber with 6 different thick caps incorporated with the unfolding technique, was used to determine the gamma-ray spectrum in the THOR epithermal neutron beam, which contains intense neutrons and gamma rays. The applied gaps had nominal thicknesses from 1 to 6 mm. Detector response functions of the applied Mg(Ar) chamber with different caps were calculated using MCNP5 with a validated chamber model. The spectrum unfolding process was performed using the well-known SAND-II algorithm. The unfolded result was found much softer than the originally calculated spectrum at the design stage. A large portion of low energy continuum was shown in the adjusted spectrum. This work gave us much deeper insight into the THOR epithermal neutron beam and also showed a way to determine the gamma-ray spectrum.

LIU Yuan-Hao;  LIN Yi-Chun;  NIEVAART Sander;  CHOU Wen-Tsae;  LIU Hong-Ming;  JIANG Shiang-Huei; 

2011-12-22

ELSEVIER SCIENCE BV

JRC62904

0168-9002,   

www.elsevier.com/locate/nima,    https://publications.jrc.ec.europa.eu/repository/handle/JRC62904,   

10.1016/j.nima.2010.11.184,