Word: nuclei
(lookup in dictionary)
(lookup stats)
Dates: during 1970-1979
Sort By: most recent first
(reverse)
Fast Neutrons. Unlike the more familiar process of fission (in which energy is released by the breakup of atomic nuclei), fusion involves the combining (or fusing) of two nuclei of hydrogen. The reaction releases energy-primarily in the form of high-velocity neutrons-that scientists hope some day can be harnessed to generate electricity...
...more efficient tool for creating fusion: the laser. By heating a tiny pellet of deuterium or tritium with a powerful pulse of laser light, they cause the explosive evaporation of the pellet's surface. As the material sprays off, the rest of the pellet implodes. The hydrogen nuclei are thus forced together. As early as 1968, a team of Soviet researchers under Physicist Nikolai Basov, a Nobel laureate, reported that they had used lasers to ignite a brief but clearly detectable fusion reaction. Since then, their experiments have been repeated-and improved upon-in a number of countries, including...
...greatest deterrent to amateur bombmaking was the scarcity of the key ingredient. Both weapons and nuclear reactors need fissionable material to sustain a chain reaction -the familiar energy-producing process in which tiny, fast-moving neutrons released by the breakup (fission) of one unstable atom smash into the nuclei of neighboring atoms, causing them to split. The common reactor fuel-which was also used in the bomb that leveled Hiroshima-is a fissionable isotope of uranium called U-235. But U-235 accounts for only about one out of every 140 atoms of uranium in nature, and it takes enormously...
...know of a world with a million moons. I know of a sun the size of the earth -and made of diamond. There are atomic nuclei a mile across that rotate thirty times a second. There are tiny grains between the stars, with the size of and composition of bacteria ... The universe is vast and awesome, and for the first time we are becoming part...
Perrin suspects that water, filtering down through the Oklo deposit, became an accessory to the chain reaction. Acting as a "moderator," subsurface water slowed down the neutrons emerging from splitting U-235 atoms enough to allow them to hit and split the nuclei of other U-235 atoms. (Without a moderator, the neutrons escape from the uranium fuel too fast to sustain the reaction.) When the heat from this process became too intense, scientists believe, the water turned to steam, the neutrons speeded up, and the chain reaction halted until the uranium cooled sufficiently for the steam to condense back...