Science

HOW TO ‘SEE' A NEUTRINO

May 4 1998
Science

HOW TO ‘SEE' A NEUTRINO

May 4 1998

HOW TO ‘SEE' A NEUTRINO

Every second, each of the approximately 100 billion stars in our galaxy, including Earth’s sun, discharges trillions upon trillions of neutrinos—one of the tiniest particles known to science. As far as physicists now understand, neutrinos are elementary entities, meaning they

are indivisible. They also pass through just about everything unhindered, which means they have been almost impossible to observe. That is about to change. Starting in July, the new, $74-million Sudbury Neutrino Observatory will allow physicists, if not to see the mysterious subatomic particles directly, at least to observe what they can do.

The facility is designed to reveal the flashes of light emitted when

neutrinos smash into molecules of heavy water and break off an electron. If SNO scientists can then confirm their assumption that neutrinos have mass, that would go a long way towards explaining an enduring astrophysical mystery: why the total mass of all known celestial bodies is only a fraction of what scientists calculate the mass of the universe ought to be.