Investigation of enhancement in planar fast neutron detector efficiency with stacked structure using Geant4

• Published in: Nuclear science and techniques 2017-11, Vol.28 (11), p.219-228, Article 154
• Main Authors: Tripathi, Shivang, Upadhyay, Chandrakant, Nagaraj, C. P., Devan, K., Venkatesan, A., Madhusoodanan, K.
• Format: Article
• Language: English
• Subjects: Energy; Hadrons; Heavy Ions; Nuclear Energy; Nuclear Physics
• ISSN: 1001-8042; 2210-3147
• DOI: 10.1007/s41365-017-0315-7

Geant4 based Monte Carlo study has been carried out to assess the improvement in efficiency of the planar structure of Silicon Carbide (SiC)-based semiconductor fast neutron detector with the stacked structure. A proton recoil detector was simulated, which consists of hydrogenous converter, i.e., high-density polyethylene (HDPE) for generating recoil protons by means of neutron elastic scattering ( n , p ) reaction and semiconductor material SiC, for generating a detectable electrical signal upon transport of recoil protons through it. SiC is considered in order to overcome the various factors associated with conventional Si-based devices such as operability in a harsh radiation environment, as often encountered in nuclear facilities. Converter layer thickness is optimized by considering 10 9 neutron events of different monoenergetic neutron sources as well as 241 Am-Be neutron spectrum. It is found that the optimized thickness for neutron energy range of 1–10 MeV is ~ 400 μm. However, the efficiency of fast neutron detection is estimated to be only 0.112%, which is considered very low for meaningful and reliable detection of neutrons. To overcome this problem, a stacked juxtaposition of converter layer between SiC layers has been analyzed in order to achieve high efficiency. It is noted that a tenfold efficiency improvement has been obtained—1.04% for 10 layers stacked configuration vis-à-vis 0.112% of single converter layer detector. Further simulation of the stacked detector with respect to variable converter thickness has been performed to achieve the efficiency as high as ~ 3.85% with up to 50 stacks.