Featured Research

from universities, journals, and other organizations

Sensitive Measurement By Sudbury Neutrino Observatory Observes Solar Neutrinos In A New Way

Date:
April 22, 2002
Source:
Brookhaven National Laboratory
Summary:
A team of scientists from Canada, the US and the UK announced the results of a unique new measurement of the total number of all known neutrino types reaching the Earth from the Sun. Using data entirely from the Sudbury Neutrino Observatory (SNO) in Canada they are also able to determine that the observed number of electron neutrinos (the type produced by the Sun) is only a fraction of the total number. This shows with great certainty that neutrinos from the Sun change from one type to another before reaching the Earth.

April 20, 2002 -- A team of scientists from Canada, the US and the UK today announced the results of a unique new measurement of the total number of all known neutrino types reaching the Earth from the Sun. Using data entirely from the Sudbury Neutrino Observatory (SNO) in Canada they are also able to determine that the observed number of electron neutrinos (the type produced by the Sun) is only a fraction of the total number. This shows with great certainty that neutrinos from the Sun change from one type to another before reaching the Earth.

Related Articles


Says Project Director Art McDonald of Queen's University, "These new results show in a clear, simple and accurate way that solar neutrinos change their type. The total number of neutrinos we observe is also in excellent agreement with calculations of the nuclear reactions powering the Sun. The SNO team is really excited because these measurements enable neutrino properties such as mass to be specified with much greater certainty for fundamental theories of elementary particles."

Neutrinos are particles with no electric charge and very little mass. They are known to exist in three types related to three different charged particles - the electron and its lesser known relatives the muon and the tau. The Sun emits electron-neutrinos, which are created in the thermonuclear reactions in the solar core. Previous experiments have found fewer electron-neutrinos than suggested by calculations based on how the Sun burns - the famous "solar neutrino problem."

SNO uses the unique properties of heavy water - where the hydrogen has an extra neutron in its nucleus - to detect not only electron-neutrinos through one type of reaction, but also all three known neutrino types through a different reaction. The results presented today at the Joint American Physical Society/American Astronomical Society meetings in Albuquerque, New Mexico show that the number of electron-neutrinos observed is only about 1/3 of the total number reaching the Earth. This shows unambiguously that electron-neutrinos emitted by the Sun have changed to muon- or tau-neutrinos before they reach Earth.

Dr. Andre Hamer of Los Alamos National Laboratory told the meeting, "In order to make these measurements we had to restrict the radioactivity in the detector to minute levels and determine the background effects very accurately to show clearly that we are observing neutrinos from the Sun. The care taken throughout this experiment to minimize radioactivity and the careful calibration and analysis of our data has enabled us to make these neutrino measurements with great accuracy."

In June 2001, results from the detection of electron-neutrinos in SNO first indicated, with a certainty of 99.9%, that neutrinos change type on their way from the Sun, thus solving the long-standing problem. However, these conclusions were based on comparisons of results from SNO with those from a different experiment, the Super-Kamiokande detector in Japan. The new results, obtained entirely from the SNO, are so accurate that it is 99.999% probable that solar neutrinos change type before reaching Earth. The results, which have been submitted to Physical Review Letters, are of great importance because the way in which the neutrinos - long thought to be massless particles - change types is thought to be linked to neutrino mass and mass differences between various neutrino types.

Says Professor Hamish Robertson of the University of Washington, "It was a dramatic and exciting moment for us when we first saw the neutrons being produced by this type of neutrino interaction and realized there were three times as many as you would get if only electron neutrinos were coming from the Sun. There's absolutely no question the neutrino type changes and now we know quite precisely the mass differences between these particles."

Dr. Richard (Dick) Hahn, leader of the Brookhaven National Laboratory group that is working in SNO, agreed. "These results are exciting because they demonstrate the full potential of the SNO neutrino detector," said Hahn. "All of the collaboration's hard work over many years is really paying off now."

Brookhaven's history of neutrino research dates to the early 1970s, when scientist Ray Davis's pioneering work in a South Dakota gold mine sent the neutrino world into an uproar by first documenting the missing electron neutrinos.

* Collaborating institutions -- From Canada: Queen's University, Carleton University, Laurentian University, University of Guelph, University of British Columbia, Chalk River Laboratories (to 1996). From the U.S.: Lawrence Berkeley National Laboratory, Los Alamos National Laboratory, University of Pennsylvania, University of Washington, Brookhaven National Laboratory, Princeton University (to 1992), University of California at Irvine (to 1989). From the U.K.: Oxford University.

The U.S. Department of Energy's Brookhaven National Laboratory (http://www.bnl.gov) conducts research in the physical, biomedical, and environmental sciences, as well as in energy technologies. Brookhaven also builds and operates major facilities available to university, industrial, and government scientists. The Laboratory is operated by Brookhaven Science Associates, a limited liability company founded by Stony Brook University and Battelle, a nonprofit applied science and technology organization.


Story Source:

The above story is based on materials provided by Brookhaven National Laboratory. Note: Materials may be edited for content and length.


Cite This Page:

Brookhaven National Laboratory. "Sensitive Measurement By Sudbury Neutrino Observatory Observes Solar Neutrinos In A New Way." ScienceDaily. ScienceDaily, 22 April 2002. <www.sciencedaily.com/releases/2002/04/020422072526.htm>.
Brookhaven National Laboratory. (2002, April 22). Sensitive Measurement By Sudbury Neutrino Observatory Observes Solar Neutrinos In A New Way. ScienceDaily. Retrieved January 30, 2015 from www.sciencedaily.com/releases/2002/04/020422072526.htm
Brookhaven National Laboratory. "Sensitive Measurement By Sudbury Neutrino Observatory Observes Solar Neutrinos In A New Way." ScienceDaily. www.sciencedaily.com/releases/2002/04/020422072526.htm (accessed January 30, 2015).

Share This


More From ScienceDaily



More Space & Time News

Friday, January 30, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

NASA Holds Memorial to Remember Astronauts

NASA Holds Memorial to Remember Astronauts

AP (Jan. 29, 2015) NASA is remembering 17 astronauts who were killed in the line of duty and dozens more who have died since the agency&apos;s beginning. A remembrance ceremony was held Thursday at NASA&apos;s Marshall Space Flight Center in Alabama. (Jan. 29) Video provided by AP
Powered by NewsLook.com
Asteroid's Moon Spotted During Earth Flyby

Asteroid's Moon Spotted During Earth Flyby

Rumble (Jan. 27, 2015) Scientists working with NASA&apos;s Deep Space Network antenna at Goldstone, California discovered an unexpected moon while observing asteroid 2004 BL86 during its recent flyby past Earth. Credit to &apos;NASA JPL&apos;. Video provided by Rumble
Powered by NewsLook.com
Water Fleas Prepare for Space Voyage

Water Fleas Prepare for Space Voyage

Reuters - Innovations Video Online (Jan. 26, 2015) Scientists are preparing a group of water fleas for a unique voyage into space. The aquatic crustaceans, known as Daphnia, can be used as a miniature model for biomedical research, and their reproductive and swimming behaviour will be tested for signs of stress while on board the International Space Station. Jim Drury went to meet the team. Video provided by Reuters
Powered by NewsLook.com
Mars Rover Opportunity Celebrates 11-Year Anniversary

Mars Rover Opportunity Celebrates 11-Year Anniversary

Rumble (Jan. 26, 2015) Eleven years ago NASA&apos;s Opportunity rover touched down on Mars for what was only supposed to be a 90-day mission. Since then it has traveled 25.9 miles (41.7 kilometers), further than any other off-Earth surface vehicle has ever driven. Credit to &apos;NASA&apos;. Video provided by Rumble
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:

Strange & Offbeat Stories


Space & Time

Matter & Energy

Computers & Math

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins