(Annihilation with a moving positron) A positron travelling with kinetic energy…

PHYSICS · Subjective · A Level · Physics · Particles and radiation · Particles and radiation

Problem

(Annihilation with a moving positron) A positron travelling with kinetic energy K=3.0×10−13 JK=3.0\times10^{-13}\,\text{J} collides head-on with an electron that is at rest. The two particles annihilate to form two photons which move in opposite directions and share the liberated energy equally. Constants: me=9.11×10−31 kgm_{e}=9.11\times10^{-31}\,\text{kg}, h=6.63×10−34 J sh=6.63\times10^{-34}\,\text{J s}, c=3.00×108 m s−1c=3.00\times10^{8}\,\text{m s}^{-1} (a) Find the total energy released in the annihilation. (b) Determine the energy of each photon. (c) Calculate the corresponding wavelength of the photons, giving the answer to three significant figures.

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