# With Compton scattering, does the deflection angle depend on particle size?

• FrankJ777
FrankJ777
I'm researching a bit on Compton Scattering, especially in relation to, backscattering scanner, like one would see in an airport. I think I understood that the angle of deflection is in relationship to the loss of energy of the photon, where λf - λi = h/mc(1-cosθ). So if you know the origional frequency and the final frequency you can calculat the angle. But there's a few things I'm trying to understand.

Is the deflection angle, θ dependent on the mass of the particle it bounces off of?

Is the h/mc(1-cosθ), the energy imparted into the particle?

Since I'm researching backscatter scanners, where in that case i'd think, since the collector is colocated with the tranmitter, meaning a 180° reflection angle, then all rays obsorved would have lost h/mc(1-cos(180)) = 2h/mc. So I'm wondering if that is just a convenient angle to measure frm an engineering standpoint, or if that provides a benifite to identify certain materials (by the fact that they cause a photon to scatter at 180° angle.

I hope my question makes some sense.

Thanks