Sunspots and neutrinos.Sunspots sunspots, dark, usually irregularly shaped spots on the sun's surface that are actually solar magnetic storms. The Chinese recorded dark features on the sun seen with the naked eye in 28 B.C. and neutrinos According to according to prep. 1. As stated or indicated by; on the authority of: according to historians. 2. In keeping with: according to instructions. 3. the so-called standard solar model The Standard Solar Model (SSM) is the best current physical model of our sun. Very generally, in the Standard Solar Model the sun is a ball of mostly hydrogen plasma which is held together through self gravitation. , nuclear fusion reactions at the sun's center pump out vast quantities of energy. About 2 percent of that energy should appear in the form of neutrinos -- fundamental particles that interact only weakly with matter. But that's not what researchers see. Data collected by an Earth-based detector over a period of 20 years suggest that the neutrino neutrino (n  trē`nō) [Ital.,=little neutral (particle)], elementary particle with no electric charge and a very small mass emitted during the decay of certain other particles. flow from the sun varies from time to time rather than remaining constant. Moreover, the flux seems to follow a pattern that runs counter to the rise and fall in the number of sunspots visible on the sun's surface. "This time variation of the neutrino flux coincides with the well-known 11-year cycle of solar activity," says physicist Kenneth Lande of the University of Pennsylvania (body, education) University of Pennsylvania - The home of ENIAC and Machiavelli. http://upenn.edu/. Address: Philadelphia, PA, USA. in Philadelphia. The neutrino flux is high when solar activity is low and declines to near-zero values as the number of sunspots rises to a peak. Lande reported the latest measurements from a neutrino detector deep in the Homestake gold mine near Lead, S.D., at this week's American Physical Society The American Physical Society was founded in 1899 and is the world's second largest organization of physicists. The Society publishes more than a dozen science journals, including the world renowned Physical Review and Physical Review Letters, and organizes more than twenty science meeting in Washington, D.C. The measurements clearly show a sharp drop in neutrino flux starting last year -- just as the present solar cycle approached its maximum. Such a rise and fall in neutrino flow, detected now for the second time in two decades, hints that the effect is real, Lande says. The chance of such a pattern happening randomly is less than 1 percent, according to computer simulations. At its peak, the neutrino flux is reasonably close to the value theorists predict the flux from the sun should have. "You can think of the peak level as being the real neutrino flux and the reduced level as being the attenuated Attenuated Alive but weakened; an attenuated microorganism can no longer produce disease. Mentioned in: Tuberculin Skin Test attenuated having undergone a process of attenuation. or modulated level," Lande says. "Something does something to the neutrinos." No one yet has a clear picture of what exotic mechanism may be responsible for altering the fundamental nature of neutrinos coming from the sun's center or for the apparent link between solar activity and neutrino physics. Preliminary results expected later this year from two new neutrino detectors should help clarify the matter (SN: 10/28/89, p.282). |
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