Word: antiproton
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DIED. OWEN CHAMBERLAIN, 85, Nobel-prizewinning physicist at the University of California, Berkeley; in Berkeley, Calif. Chamberlain worked on the Manhattan Project and later apologized to the Japanese for the Hiroshima and Nagasaki bombings. In 1955, he and fellow Manhattan Project alum Emilio Segre identified the antiproton, the negatively charged mirror of the subatomic particle, a discovery that sparked still unresolved debates about the composition of the universe...
...three basic particles of antimatter—positron, antiproton and antineutron—share the same masses and magnitudes of charge as those of their counterparts in matter—electron, proton and neutron, but with opposite charges. Just as a proton and electron compose a hydrogen atom, an antiproton and positron make an antihydrogen atom. When matter and antimatter particles collide, they destroy each other in a burst of energy...
After 18 years of work, Gabrielse, who leads an international team of physicists at the European Organization for Nuclear Research, has already found a way to produce the slowest antiprotons on earth—an important step towards understanding antimatter since the slower the antiproton, the easier it is to measure its properties accurately...
First, Gabrielse used lasers to excite the electron in a cesium atom into a higher orbit. When the cesium atom collides with a positron, the electron binds with the positron, to create an atom that is half matter and half antimatter. When that atom collides with an antiproton, the positron binds to the antiproton, forming an antihydrogen atom...
...addition, Gabrielse’s team was able to measure the distance between the positron and antiproton in an antihydrogen atom by the magnitude of the voltage required to pull the two particles apart, enabling them to better map the internal structure of the atom...