Word: antiproton
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...bubble-chamber picture (see cut), an antiproton from the Bevatron enters at bottom and hits a proton (1): out of the collision come one lambda and one anti-lambda particle. Since both are neutral electrically, they leave no tracks in the liquid hydrogen, but after a short, invisible career, each decays into track-leaving particles by which it can be identified. The lambda ( 2) turns into a proton and a negative pi meson, both of which go off the picture leaving strong curved tracks. The anti-lambda (3) turns into an antiproton and a positive pi meson. The positive...
...great bevatron at Berkeley creates antiprotons (protons with negative charges, in fair quantities. When they hit particles of ordinary matter-protons, neutrons, etc.-they generally annihilate themselves and their targets, both turning into weightless energy and neutrinos. About a fortnight ago an antiproton observed by Dr. Segrè and Dr. Wilson M. Powell behaved differently. It entered Dr. Segrè's bubble chamber, which is filled with liquid propane on the point of boiling, and made its normal, slightly curving trail of tiny bubbles (see cut). Suddenly the trail stopped, and a "star" of four diverging bubble trails appeared...
Star of Suicides. Dr. Segrè has no doubt about what happened. The antiproton, he says, hit an ordinary, positively charged proton and reacted with it in such a way that the collision produced one ordinary neutron and one antineutron. These two particles differ only in their magnetic properties. Neither has any electric charge, and therefore they left no bubble trails. The neutron shot out of the picture undetected, but the antineutron hit a carbon atom in the propane and committed double suicide with one of its protons or neutrons. The atom disintegrated, leaving a star of bubble trails made...
Like the identification nearly a year ago of the antiproton (TIME, Oct. 31), the work was done with the Berkeley Bevatron, the world's most powerful particle accelerator, and a long train of auxiliary apparatus. The Bevatron's beam of 6.2 billion-volt protons was shot into a beryllium target. Out of the target came a secondary beam of assorted atomic debris. The particles with a negative charge, separated from the rest by the Bevatron's strong magnetic field, were mostly mesons. Among them were a few antiprotons (negative protons) formed when the Bevatron's powerful...
Most of these antiprotons were "annihilated" (turned into energy) when they hit an ordinary positive proton. But occasionally, when an antiproton passed close to an ordinary proton, it merely handed over its negative electric charge. The proton, its positive charge neutralized by a negative one, became an ordinary, chargeless neutron. The antiproton, having lost its negative charge and received nothing in return, also became a chargeless particle, but it did not become a normal neutron. Since its basic "anti-ness" was not changed by the loss of its charge, it became an antineutron with a reversed magnetic field...