SITE VISIT: On the Trail of Neutrinos

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Science  16 Apr 1999:
Vol. 284, Issue 5413, pp. 395
DOI: 10.1126/science.284.5413.395d

Neutrinos may be the most elusive particles ever. First predicted in 1931, then finally detected in 1956, the subatomic beasts have only recently divulged some of their properties, such as the fact that they have mass. To help track the latest findings, Juha Peltoniemi, a physics docent at the University of Helsinki, created The Ultimate Neutrino Page. Since 1996, the Web site has offered a handy resource for data on neutrinos and other particles, as well as links to neutrino experiments around the world.

Peltoniemi says the most popular section is a table of experimental results on how many neutrinos the sun emits. For decades, physicists have puzzled over the enormous discrepancy between experiments and theory in this area, wondering if, for example, neutrinos oscillate among different incarnations that sometimes elude detection. “People find it very useful to see an up-to-date comparison of all the results with the theoretical predictions,” Peltoniemi explains.

The Ultimate Neutrino page also has educational applets. One lets you plug in different mass values for the three neutrino “flavors” and see if the results make sense for, say, dark matter or solar physics. And the Automatic Model Builder lets you pick a particle physics model (supersymmetry, for example), make assumptions (such as that neutrinos have mass), and see whether neutrinos could be the missing dark matter in the universe.

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