Optimized cooling design of solid targets for 2.5 MeV H⁺ accelerator-based neutron sources to enhance fast neutron yield

Abstract Developing neutron-generating targets will facilitate the widespread use of compact accelerator-driven neutron sources. The RIKEN compact accelerator neutron systems (RANS) was used for neutron imaging research. RANS uses solid Be targets to produce neutrons based on <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mmultiscripts> <mml:mrow> <mml:mi mathvariant="normal">Be</mml:mi> </mml:mrow> <mml:none/> <mml:none/> <mml:mprescripts/> <mml:none/> <mml:mrow> <mml:mn>9</mml:mn> </mml:mrow> </mml:mmultiscripts> <mml:mspace width="1em"/> <mml:mo stretchy="false">(</mml:mo> <mml:mi mathvariant="normal">p</mml:mi> <mml:mo>,</mml:mo> <mml:mi mathvariant="normal"> n</mml:mi> <mml:mo stretchy="false">)</mml:mo> <mml:mspace width="1em"/> <mml:mmultiscripts> <mml:mrow> <mml:mi mathvariant="normal">B</mml:mi> </mml:mrow> <mml:none/> <mml:none/> <mml:mprescripts/> <mml:none/> <mml:mrow> <mml:mn>9</mml:mn> </mml:mrow> </mml:mmultiscripts> <mml:mspace width="1em"/> </mml:math> nuclear reactions, whereas RANS-II uses solid Li targets to produce neutrons based on <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mmultiscripts> <mml:mrow> <mml:mi mathvariant="normal">Li</mml:mi> </mml:mrow> <mml:none/> <mml:none/> <mml:mprescripts/> <mml:none/> <mml:mrow> <mml:mn>7</mml:mn> </mml:mrow> </mml:mmultiscripts> <mml:mspace width="1em"/> <mml:mo stretchy="false">(</mml:mo> <mml:mi mathvariant="normal">p</mml:mi> <mml:mo>,</mml:mo> <mml:mi mathvariant="normal">n</mml:mi> <mml:mo stretchy="false">)</mml:mo> <mml:mspace width="1em"/> <mml:mmultiscripts> <mml:mrow> <mml:mi mathvariant="normal">Be</mml:mi> </mml:mrow> <mml:none/> <mml:none/> <mml:mprescripts/> <mml:none/> <mml:mrow> <mml:mn>7</mml:mn> </mml:mrow> </mml:mmultiscripts> <mml:mspace width="1em"/> </mml:math> nuclear reactions. For the existing solid lithium target used in RANS-II, the design of the cooling water structure in the direction of neutron extraction influences the yield of the fast-neutron beam. Based on RANS-II, in this study, a new target cooling structure was designed and fabricated, and its cooling performance was verified through beam irradiation experiments and thermal calculations. The fabricated circulation system was found to increase the fast neutron yield by 40% at the 0 m position.