Nuclear & Particle Physics - Photon Scattering

Photons of wavelength λ scatter elastically on free protons initially at rest. The wavelength of the photons scattered at 90^o is increased by

1. λ ⁄ 137
2. λ ⁄ 1836
3. ħ ⁄ (m_ec) where ħ Planck's constant, m_e the rest mass of an electron, and c the speed of light
4. ħ ⁄ (m_pc) where ħ Planck's constant, m_p the rest mass of a proton, and c the speed of light
5. zero

(GR8677 #45)

Solution:

Compton Scattering: the inelastic scattering of photons from charged particles.

θ = 90^o → cos θ = 0
For proton scattered at 90^o, Δλ = ħ ⁄ (m_pc)

Answer: D