14. Which of the following statements are correct?【複選題】 
(A) If the mean track length of 100 MeV tt mesons is 4.88 m up to the point of decay, their mean lifetimeis

s.
(B) A neutrino of energy 2 GeV collides with an electron. The maximum momentum transfer to theelectron is 2.0437 GeV/c.
(C) A positron-electron pair production can occur in the interaction of a gamma ray with electron, via

 
(D) A linear accelerator produces a beam of excited carbon atoms of kinetic energy 120 MeV. Lightemitted on de-excitation is viewed at right angles to the beam and has a wavelength λ'. If λ is thewavelength emitted by a stationary atom, the value of (λ' -λ) /λ = 0.0099. (Take the rest energies ofboth protons and neutrons to be 109 eV).
(E) All statements are correct.