Word: alpha
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Dates: during 1930-1939
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...following the clues of radio-activity that Drs. Pauli and Chadwick separately reached their conclusions. Recently Professor Walther Bothe of Giessen, Germany, bombarded the element beryllium with alpha particles. Something happened to the alpha particles. The particles contained four units of positive electricity (protons) and two of negative electricity (electrons) when they crashed into the beryllium. Two protons of an alpha particle seemed to cling to the nucleus of a beryllium atom (thereby theoretically transmuting that atom of beryllium into an atom of carbon). The particle's other two protons and the two electrons seemed changed into what Professor...
...proton, which is 1,845 times as heavy as an electron, might make an electron its satellite. Such a simple system of one electron revolving around one proton makes up a common atom of hydrogen, simplest of the 92 elements. (Helium, next simplest, has an alpha particle for its core, two electrons for satellites. Other atoms have more protons, more electrons...
That is the neutron. It lacks electrical characteristics. The charges of proton and electron have bound and balanced each other. A particle has been formed halfway between nascent electricity and atomic hydrogen. It hops out of radioactive substances as do alpha particles...
Neutrons move much faster than alpha particles, and they have great penetrating powers. They can travel through a mile of air, several feet of lead. They apparently weigh 200,000,000,000,000,000,000,000 to the ounce. It is only by the finest of discernment that they can be distinguished from unentangled quanta of energy. Streams of them may be what Dr. Robert Andrews Millikan calls cosmic rays. But Dr. Chadwick doubts that. Neutrons may be, because they have opposite poles, the long sought units of magnetism. Whatever they are, neutrons are fine things for physicists to play...
...described two meticulous counters:1) the device of Dr. Merle Anthony Tuve of the Carnegie Institution (TIME, Feb. 8), which measures a current of one electron per second, smallest current measured so far; 2) the device (including thyratron tubes) of Dr. Wynn Williams of Cambridge University, England, which counts alpha particles (nuclei of helium atoms) as they explode from radium at a speed of 12,000 mi. per sec., and ten microseconds apart. (A microsecond is one-millionth of a second.) Dr. Kenneth T. Bainbridge of Bartol Laboratories, Philadelphia, again described his two-ton mass-spectrograph which is sensitive...