page_title: Delta ray
section_title: Characteristics
hierarchical_section_title: Delta ray / Characteristics
caption_attribution_description: English: This rare picture show the 4 type of charged particles that we can detect in a cloud chamber&#160;: alpha, proton, electron and muons (probably). Picture taken at the Pic duMidi at 2877 m in a Phywe PJ45 diffusion cloud chamber. Size of the interaction surface if 45x45 cm
context_page_description: A delta ray is a secondary electron with enough energy to escape a significant distance away from the primary radiation beam and produce further ionization", and is sometimes used to describe any recoil particle caused by secondary ionization. The term was coined by J. J. Thomson.
context_section_description: A delta ray is characterized by very fast electrons produced in quantity by alpha particles or other fast energetic charged particles knocking orbiting electrons out of atoms. Collectively, these electrons are defined as delta radiation when they have sufficient energy to ionize further atoms through subsequent interactions on their own. Delta rays appear as branches in the main track of a cloud chamber (See Figs. 1,2). These branches will appear nearer the start of the track of a heavy charged particle, where more energy is imparted to the ionized electrons.
caption: Fig. 1: Image taken in the Pic du Midi at 2877 m in a Phywe PJ45 cloud chamber (size of surface is 45 x 45 cm). This picture shows the four particles that are detectable in a cloud chamber : proton, electron, muon (probably) and alpha.  Delta rays are seen associated with the proton track.
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