PAIR PRODUCTION :PAIR PRODUCTION By: Maria Bonilla


OBJECTIVES :OBJECTIVES Definition pair production. Requirements for pair production to happen. Process of pair production Resultant of pair production Conclusion Questions


DEFINITION :DEFINITION Because gamma rays (photons) have no charge and zero mass, it might be expected that they do not interact with matter. Although they have a much greater penetrating distance through material atoms than alpha or beta, they do interact. There are three processes through which gamma rays transfer their energy: the photoelectric effect, compton scattering, and pair production.


DEFINITION :DEFINITION Pair production is the formation or materialization of two electrons, one negative and the other positive (positron), from a pulse of electromagnetic energy traveling through matter, usually in the vicinity of an atomic nucleus. Pair production is a direct conversion of radiant energy to matter. It is one of the principal ways in which high-energy gamma rays are absorbed in matter


REQUIREMENTS :REQUIREMENTS For pair production to occur, the electromagnetic energy in a discrete quantity called a photon, must be at least equivalent to the mass of two electrons. To produce two electrons, therefore, the photon energy must be at least 1.02 MeV.


PROCESS :PROCESS A high speed gamma ray is projected at a nucleus of matter (e.g. a Lead nucleus). Each gamma ray photon loses its energy, when it collides with the nucleus, producing an electron positron pair.


PROCESS :PROCESS The mass m of a single electron is equivalent to 0.51 million electron volts (MeV) of energy E as calculated from the equation formulated by Albert Einstein, E = mc2, in which c is a constant equal to the velocity of light. Photon energy in excess of amount of 1.02 MeV, when pair production occurs, is converted into motion of the electron-positron pair.


RESULTANT :RESULTANT Some of the energy is converted into the mass of the electron and positron. The rest is the kinetic energy of the electron and the position, conserving energy and momentum. The negatron interact with atom around it, causing ionization and excitation, and positron loses some energy because of the interaction and ultimately undergoes annihilation.


CONCLUSION :CONCLUSION The photon’s force energy is too high that when pass near the nucleus, this energy became in matter, and form two electrons one negative and other positron.


QUESTION :QUESTION 1.- What is a pair production?


Answer :Answer Pair production is the formation or materialization of two electrons, one negative and the other positive (positron), from a pulse of electromagnetic energy traveling through matter, usually in the vicinity of an atomic nucleus.


QUESTION :QUESTION 2.- What is the minimum of energy that must be the photon?


ANSWER :ANSWER The photon energy must be at least 1.02 MeV.


QUESTION :QUESTION 3.- What is the mass of a single electron equivalent?


ANSWER :ANSWER The mass of a single electron is equivalent to 0.51 million electron volts (MeV) of energy.


QUESTIONS :QUESTIONS 4.- What happen with the gamma rays when them collide with the nucleus?


ANSWER :ANSWER Each gamma ray photon loses its energy, producing an electron positron pair.


QUESTION :QUESTION 5.- What "type" of pair is created in pair production?


ANSWER :ANSWER It is created two electrons one negative and other positive (positron).