# Homework Help: Elastic scattering

1. Jan 20, 2012

### matt222

1. The problem statement, all variables and given/known data

2. Relevant equations

T=2*(m*M/(m+M)^2)*E(initial)*(1-cos(angle)), T is transfered energy from the neutron to the target.

displacement energy for Zr=40eV

3. The attempt at a solution

the question is strange for me it seems to me there is a trick since we dont have the initial energy of the incident particle!

I cant start solving without knowing the energy of the incident particle! any help please!

Last edited: Jan 20, 2012
2. Jan 20, 2012

### HallsofIvy

What are you trying to solve that equation for? You are given everything except the initial energy. Solve for that and use it to find the initial speed of the neutron.

3. Jan 20, 2012

### matt222

Yes this is the trick now!
we need to find the minimum energy (in eV) of the neutron to displace two Zr in a row
what i can do is as follow:

total incident neutron energy is equal E, transfered energy to the target is T, neutron energy after scattering is Q, so that totat energy is :

E=T+Q

BUT here i lost what do you think about my idea