Antiproton (bottom of the photograph) entering the 72-inch hydrogen bubble chamber at the University of California's Lawrence Radiation Laboratory

Antiproton (bottom of the photograph) entering the 72-inch hydrogen bubble chamber at the University of California's Lawrence Radiation Laboratory, Berkeley.  The four-pronged 'stars' are formed when an antiproton, generated by the Bevatron, come close to protons, the nucleus of ordinary hydrogen atom, in the chamber. The process is called annihilation, and is visualized by the profusion of tracks forming the stars. The secondary tracks are made by particles of lower mass into which the primary particles disintegrate.  Not all of the particles are seen -- the neutral ones (those with no electrical charge) make no tracks.  It had been theoretically postulated that the Omega meson is composed of three pi mesons (pions), and is neutrally charged. By making elaborate analyses of pictures such as this, it was possible to determine that in one of the 'stars' and Omega meson had been born in the annihilation, had existed briefly (but is invisible because of its neutrality) and had then broken up into three pions. Two of the pions show up in the four-pronged star, and the third, being neutrally charged, is invisible., Credit Line: Lawrence Berkeley National Laboratory, courtesy of AIP Emilio Segrè Visual Archives
Abstract/Description: Antiproton (bottom of the photograph) entering the 72-inch hydrogen bubble chamber at the University of California's Lawrence Radiation Laboratory, Berkeley. The four-pronged 'stars' are formed when an antiproton, generated by the Bevatron, come close to protons, the nucleus of ordinary hydrogen atom, in the chamber. The process is called annihilation, and is visualized by the profusion of tracks forming the stars. The secondary tracks are made by particles of lower mass into which the primary particles disintegrate. Not all of the particles are seen -- the neutral ones (those with no electrical charge) make no tracks. It had been theoretically postulated that the Omega meson is composed of three pi mesons (pions), and is neutrally charged. By making elaborate analyses of pictures such as this, it was possible to determine that in one of the 'stars' and Omega meson had been born in the annihilation, had existed briefly (but is invisible because of its neutrality) and had then broken up into three pions. Two of the pions show up in the four-pronged star, and the third, being neutrally charged, is invisible.
Subject(s): Laboratories
Particle accelerators
Bubble chambers
Nuclear physics--Research
Charts
Diagrams
Lawrence Berkeley National Laboratory
Credit Line: Lawrence Berkeley National Laboratory, courtesy of AIP Emilio Segrè Visual Archives
Catalog ID: Lawrence Berkeley National Laboratory H18