Theoretical study of proton-induced reactions on a composite beryllium–lithium target as a BNCT neutron source

Abstract We study a composite beryllium–lithium target for low energy BNCT applications at proton accelerators. By combining the results of a recent hybrid model to calculate neutron yields with Be targets with a well-known analytical model for Li targets, we initially estimate the maximum attainable yields with a realistic bilayer target composed by 150 $$\mu $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>μ</mml:mi> </mml:math> m of 9 Be and 150 $$\mu $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>μ</mml:mi> </mml:math> m of 7 Li. We show that, in the case of 5 MeV protons, the neutron yield increase with the composite targets amounts to about 37% for the thick target and to about 44% for the thin one with respect to the pure Be case. To assess the robustness of the solution, we also extend the calculations by varying the Be layer thickness from 120 $$\mu $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>μ</mml:mi> </mml:math> m to 180 $$\mu $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>μ</mml:mi> </mml:math> m. The neutron source is then coupled to a Beam Shaping Assembly to simulate the design of a clinical beam, demonstrating advantages in terms of added flexibility in the facility construction and quality of the beam. For a more realistic evaluation of the performance of the new source, in silico dosimetry in an anthropomorphic phantom is carried out. The result could be relevant and of interest for future BNCT facilities, such as the one being constructed in Italy under the project ANTHEM.