The total mass-energy equivalence of the three kaons is: E3K 3(4.93667 108) 1.481 109 eV, where E3K combined energy of the three kaons
The combined kinetic energy of the particles after the collision is equal to the total kinetic energy of the protons before minus the combined mass energy of the three kaons. The total energy of the protons is 2 1.5 GeV. EK 3 109 1.481 109 1.519 109 eV
The combined kinetic energy is 1.519 109 eV.
(ii) The maximum number of kaons would be produced when the maximum amount of the protons’ kinetic energy is converted to mass.
n clearly has to be a whole number, therefore the maximum number of kaons produced is six. n ◊ 3 109
4.93667 108 6.077, where n is number of kaons produced
Pair Production PAIR PRODUCTION
Pair production is the formation of one electron and one positron from a gamma photon.
This happens when the photon travels through matter, usually in the vicinity of an atomic nucleus as a illustrated in Fig 23.4.4
The equation for this reaction is: : e e
The laws of conservation hold true for pair production Mass-energy:
The energy of the photons is converted into the mass of the electron/positron pair in accordance with the equation E mc2.
If the photon has more energy than the mass equivalence of the electron plus positron the excess energy appears as kinetic energy of the electron/positron pair.
Electric Charge:
The photon has no electric charge and the electron and positron have opposite charge of the same size, therefore the net charge before and after the interaction is zero. Momentum:
The total momentum of the electron/positron pair after the interaction is the same as the momentum of the photon beforehand.5
4Pair production can be generalised to include the formation of any elementary particle and its antiparticle, but for Leaving
Cert. it is acceptable to specify electron and positron creation. 5The notion that a massless particle, like a photon, can have momentum is to do with Einstein’s theory of relativity and is beyond the scope of this course.
