1. The problem statement, all variables and given/known data the question details are given in the attachment 2. Relevant equations momentum = √2mE where m is mass of neutron and E is its kinetic energy 3. The attempt at a solution initially i accounted for the energy change during the path followed by the neutron but later i got confused and is stuck up in the problem for few hours . i am not able to understand why the detector will detect a maximum . and how to relate the kinetic energy of the neutron in this question .