Turn over 21 16 The bubble chamber photograph shows tracks made by a proton and a pion. The proton and pion were both created by the decay of a lambda particle. No other particles were produced. *(a) Explain how observations and measurements from the photograph can be used to establish information about the lambda particle. (6) .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. .................................................................................................................................................................................................................................................. 22 (b) The lambda particle consists of up, down and strange quarks. Explain how the conservation of charge, baryon number and lepton number apply to the decay of the lambda particle. 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(c) Write an equation to represent the decay of the lambda (Λ) particle. (1) ................................................................................................................................................................................................................................................... ................................................................................................................................................................................................................................................... (d) The rest mass of the lambda particle is 1115 MeV / c2. (i) Calculate this mass in kg. 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Mass = ....................................................... kg Turn over 23 (ii) The rest mass of a proton is 940 MeV / c2. The rest mass of a pion is 140 MeV / c2. The kinetic energy of the lambda particle just before decay is 4.95 GeV. Calculate the total kinetic energy of the proton and pion in MeV. 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Total kinetic energy = ....................................................... MeV (Total for Question 16 = 16 marks)