{"id":2466,"date":"2014-03-27T09:07:05","date_gmt":"2014-03-27T08:07:05","guid":{"rendered":"http:\/\/www.cloudylabs.fr\/wp\/?page_id=2466"},"modified":"2025-08-31T10:05:57","modified_gmt":"2025-08-31T09:05:57","slug":"casc_elect","status":"publish","type":"page","link":"https:\/\/www.cloudylabs.fr\/wp\/casc_elect\/","title":{"rendered":"Cascades \u00e9lectromagn\u00e9tiques"},"content":{"rendered":"

Electromagnetic cascade or \u00ab\u00a0soft cascade\u00a0\u00bb (soft referring to the beta particles) comes from the interaction of a \u03b3-ray with a nucleus and materialises (pair creation effect), the resulting electrons subsequently producing new \u03b3-rays by bremsstrahlung. These materialise in turn and there is a rapid development of a ‘cascade’, the original energy being dispersed among a large number of electron and \u03b3-quanta. Alternatively, the cascade may be initiated by a fast electron. The dispersal of the energy among an increasing number of electrons and quanta necessarily involves a rapid reduction in the average energy of the particles in a cascade. When the energy of an individual electron is reduced to \u223c20 MeV (in a medium of nuclear emulsion), it is soon removed from the cascade through loss of energy by ionisation (remember the concept of critical energy<\/a> Ec<\/sub> ; When the energy of the particle is below Ec<\/sub>, the main process of energy loss is by ionisation and not more by Bremsstrahlung). As a result of such processes, the number of electrons rises to a maximum value and then declines.  During a cascade, secondary processes also happens : loss of energy by ionisation, Compton effect, deviations due to scattering which increase the divergence of the particles in the cascade and trident production.<\/p>\n

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