10. (a) (ii) What is meant by pair production? A photon of frequency 3.6 × 1020 Hz causes pair production.
Calculate the kinetic energy of one of the particles produced, each of which has a rest mass of 9.1 × 10–31 kg.
2009
10. In the Large Hadron Collider, two beams of protons are accelerated to high energies in a circular accelerator. The two beams of protons then collide producing new particles. Each proton in the beams has a kinetic energy of 2.0 GeV. Explain why new particles are formed. What is the maximum net mass of the new particles created per collision? What is the advantage of using circular particle accelerators in particle physics?
(mass of alpha particle = 6.6447 × 10–27 kg; mass of proton = 1.6726 × 10–27 kg; mass of lithium nucleus = 1.1646 × 10–26 kg; speed of light = 2.9979 × 108 m s–1 charge on electron = 1.6022 × 10–19 C)
2008
10. (a) In a circular accelerator, two protons, each with a kinetic energy of 1 GeV, travelling in opposite directions, collide. After the collision two protons and three pions are emitted. What is the net charge of the three pions? Justify your answer.
Calculate: (i) the combined kinetic energy of the particles after the collision
(ii) the maximum number of pions that could have been created during the collision. (24)
(charge on electron = 1.6022 × 10–19 C; mass of proton = 1.6726 × 10–27 kg; mass of pion = 2.4842 × 10–28 kg; speed of light = 2.9979 × 108 m s–1)
