Question

A proton with kinetic energy 200 MeV is incident on a liquid hydrogen target. Calculate the centre-of-mass energy of its collision with a nucleus of hydrogen. What kinds of particles could be produced in this collision?

Answer 1

In the collision of a particle of mass m₁ of total energy E₁ with m at rest, the centre-of-mass energy is 

E^∗ = ( m₁² + m₂² + 2m₂ E₁)^1/2 (1) 

Here, m₁ = 938 MeV, m₂ = 938 MeV, E₁ = 938 + 200 = 1,138 MeV 

Using these values in (1), we find E^∗ = 1973 MeV 

Useful energy for particle production 

= E^∗ − (m₁ + m₂) = 1, 973 − (938 + 938) = 97 MeV 

Pion can not be produced as the threshold energy is 290 MeV. Muons and electron – positron pairs are not produced in strong interactions. The resonance Δ(1, 236 MeV) also can not be produced.