Shielding problem

Dear experts,
i want to calculate the concrete wall thickness under the condition that a 18MeV proton beam hit a copper target. The attachment is my input file.Please help me check whether it is correct and how can i improve my results. Thank you very much.
123.flair (2.5 KB)

Dear @wangzhe,

I’m sorry but the scope of the forum is not to validate the input of the users but to provide support for specific questions or problem they may have.
Also, when posting a question, is important first, to give enough information about the physics case so that who reads your post can understand better your study case and second, to ask a precise question. In this way other forum user would be able to provide you with the most suitable answer to your problem.