Photonuclear reaction & Conservation of momentum

[oksuz_]

γ+²D ----> ¹H + ¹n

In this photonuclear reaction, is it possible to write the momentum balance equation as it follows,

M_Hv_H = M_nv_n

It somehow seems to wrong to me, since the incoming photon has a certain momentum, which is not taken account in the balance equation.

Thank you in advance.

 

[mathman]

Your original "equation" is not. The momentum balance is not too clear - what particles are you referring to? The outgoing particles (n and p) have momenta which sum to the momentum of te photon, assuming D is stationary.

 

[oksuz_]

I am sorry about the "+" mark between D and H. just edited it. Both incoming and outgoing particles are in motion. We should consider the momentum of the photon, should not we?

 

[mfb]

For typical photon energies, the photon momentum is tiny compared to the momenta of the proton and neutron.

 

[mathman]

If you ignore the photon momentum, the outgoing (n and p) have the same momentum,but in opposite directions.

 

[oksuz_]

Thank you all for answering. I should have thought this before. I have made a rough calculation. There is around eight orders of magnitude difference between the momentum of a photon and a proton with energy of 1 MeV.