Bubble chamber photo of sigma particle decay. The sigma lives too briefly to be seen; its presence is deduced from other particles. A neutrino enters

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Bubble chamber photo of sigma particle decay. The sigma lives too briefly to be seen; its presence is deduced from other particles. A neutrino enters unseen at bottom & collides with a proton in the bubble chamber liquid, producing the sigma & a negative muon. The sigma decays to 1 negative & 3 positive pions, & a neutral lambda which leaves no track but betrays itself when it decays at lower centre (within the loop) to a proton & a negative pion. Negative particles curl anticlockwise, positive ones clockwise in the magnetic field. One positive pion is of lower energy & forms the loop; the muon & one of the pions knock out atomic electrons which produce the two spiral tracks.

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Size: 2440px × 3553px
Photo credit: © BROOKHAVEN LABORATORY/SCIENCE PHOTO LIBRARY / Alamy / Afripics
License: Licensed
Model Released: No

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