June 5, 1998
things like electrons and quarks, are fundamental pieces of
matter according to
physicists' Standard Model.
But neutrinos are hard to detect.
in nuclear reactions and
particle collisions, they can easily pass completely through planet
Earth without once interacting with any other particle.
Constructed in an unused mine in Japan,
an ambitious large-scale experiment
designed to detect and study neutrinos is known
as Super-Kamiokande or "Super-K".
Only(!) 500 days worth of data was needed to produce
this "neutrino image" of the Sun,
to detect the neutrinos from nuclear fusion
in the solar interior.
Centred on the Sun's postion, the picture covers a significant
fraction of the sky (90x90 degrees in R.A. and Dec.).
Brighter colours represent a larger flux of neutrinos.
News: In a tantalizing recent announcement, an international collaboration of Super-K researchers has now presented evidence that the ghostly neutrinos undergo quantum mechanical oscillations, changing their particle identities and quantum properties over time. Theorists have considered neutrinos to be massless particles but these oscillations would imply that they have a very small (but nonzero) mass. Astrophysicists are taking note because even a small mass for ubiquitous, nearly undetectable neutrinos would make them accountable for a substantial fraction of the total mass of our Universe, influencing and perhaps determining its ultimate fate! A measurable mass for neutrinos would also make them candidates for the mysterious dark matter known to affect the motions of stars and galaxies, while proof of neutrino oscillations would be a step toward resolving the decades old Solar Neutrino Problem. Even skeptical scientists will be waiting impatiently to see if these results are independently confirmed.
Authors & editors:
NASA Technical Rep.: Jay Norris. Specific rights apply.
A service of: LHEA at NASA/ GSFC
&: Michigan Tech. U.