Featured Research

from universities, journals, and other organizations

Neutrinos change flavors while crossing Japan: Findings shed light on why universe is made of matter instead of anti-matter

Date:
June 15, 2011
Source:
Duke University
Summary:
By shooting a beam of neutrinos through a small slice of the Earth under Japan, physicists say they've caught the particles changing their stripes in new ways. These observations may one day help explain why the universe is made of matter rather than anti-matter.

After traveling 295 km underneath Japan, a neutrino interacted with the giant Super-K detector and was recorded by its light detectors.
Credit: Courtesy of Chris Walter, Duke

By shooting a beam of neutrinos through a small slice of Earth under Japan, physicists say they've caught the particles changing their stripes in new ways. These observations may one day help explain why the universe is made of matter rather than anti-matter.

The T2K experiment has been using the Japan Proton Accelerator Research Complex, or J-PARC, located on the east coast, to shoot a beam of muon neutrinos 185 miles, or 295 kilometers, underground toward the Super-Kamiokande, or Super-K, detector in Kamioka, near Japan's west coast.

The goal of the experiment, which is part of a new generation of neutrino-tracking facilities, is to observe the particles changing "flavors" from muon neutrinos to electron neutrinos on this brief journey.

Neutrinos are elementary particles that come in three flavors -- muon, electron and tau. In past experiments, physicists have measured the change of muon neutrinos to tau neutrinos and electron neutrinos to muon neutrinos or tau neutrinos.

"But no one had seen muon neutrinos turn into electron neutrinos," said Chris Walter, a physicist at Duke who is part of the T2K collaboration, along with Duke physicist Kate Scholberg.

The T2K collaboration, a team of physicists from around the world, began observing the neutrinos for their transformations in January 2010. The group measured the neutrinos, determining their flavor near the accelerator and then again at Super-K. So far, scientists caught 88 neutrinos with their detector. Six of these likely began their lives as muon neutrinos and turned into electron neutrinos on their way to Super-K.

"As it stands, this result is extremely interesting, but we are just getting started," Walter said. He explained that the T2K team has taken a little less than two percent of the planned neutrino measurements, partly due to the East Japan earthquake that struck on March 11, 2011 and forced the shutdown of T2K.

The preliminary findings were submitted to Physical Review Letters and announced at a press conference June 15 in Japan.

"We could see as many electron neutrino candidates as we saw by chance, something, like one out of every 150 times," Walter said. "This is why the title of our paper includes the word 'indications' as opposed to observation or measurement."

If the "indications" become "measurements," these T2K results will be the first to measure a muon-electron neutrino change. Scientists want this measurement to study a fundamental parameter of physics called theta-13, which controls the muon-electron neutrino switch. Walter said there is more than one way to measure theta-13 and that several experiments are currently competing to be the first.

"It's good news that we have evidence of a relatively large theta-13, since there are even more interesting measurements that can be done if it is big enough," he said.

If theta-13 is large, it will allow scientists to measure the difference between oscillations of neutrinos and oscillation of anti-neutrinos. Walter explained that in the early universe, "something caused there to be slightly more matter than anti-matter. When the matter and anti-matter annihilated each other, only that little bit of matter was left over. That matter is everything we see around us today. But no one understands how this happened."

"The difference between neutrino and anti-neutrino properties that we might measure in future experiments might give clues to how the excess matter was generated," Walter said.

Of course that all depends on how quickly T2K can come back online after being shut down from the earthquake. Currently, the experiment is slated to re-start at the end of 2011.


Story Source:

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


Journal References:

  1. The T2K Collaboration. Indication of Electron Neutrino Appearance from an Accelerator-produced O -axis Muon Neutrino Beam. Physical Review Letters, 2011; (submitted)
  2. The T2K Collaboration. The T2K Experiment. arXiv.org, 2011; [link]

Cite This Page:

Duke University. "Neutrinos change flavors while crossing Japan: Findings shed light on why universe is made of matter instead of anti-matter." ScienceDaily. ScienceDaily, 15 June 2011. <www.sciencedaily.com/releases/2011/06/110615103230.htm>.
Duke University. (2011, June 15). Neutrinos change flavors while crossing Japan: Findings shed light on why universe is made of matter instead of anti-matter. ScienceDaily. Retrieved July 24, 2014 from www.sciencedaily.com/releases/2011/06/110615103230.htm
Duke University. "Neutrinos change flavors while crossing Japan: Findings shed light on why universe is made of matter instead of anti-matter." ScienceDaily. www.sciencedaily.com/releases/2011/06/110615103230.htm (accessed July 24, 2014).

Share This




More Matter & Energy News

Thursday, July 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Robot Parking Valet Creates Stress-Free Travel

Robot Parking Valet Creates Stress-Free Travel

AP (July 23, 2014) 'Ray' the robotic parking valet at Dusseldorf Airport in Germany lets travelers to avoid the hassle of finding a parking spot before heading to the check-in desk. (July 23) Video provided by AP
Powered by NewsLook.com
Boeing Ups Outlook on 52% Profit Jump

Boeing Ups Outlook on 52% Profit Jump

Reuters - Business Video Online (July 23, 2014) Commercial aircraft deliveries rose seven percent at Boeing, prompting the aerospace company to boost full-year profit guidance- though quarterly revenues missed analyst estimates. Bobbi Rebell reports. Video provided by Reuters
Powered by NewsLook.com
Europe's Car Market on the Rebound?

Europe's Car Market on the Rebound?

Reuters - Business Video Online (July 23, 2014) Daimler kicks off a round of second-quarter earnings results from Europe's top carmakers with a healthy set of numbers - prompting hopes that stronger sales in Europe will counter weakness in emerging markets. Hayley Platt reports. Video provided by Reuters
Powered by NewsLook.com
9/11 Commission Members Warn of Terror "fatigue" Among American Public

9/11 Commission Members Warn of Terror "fatigue" Among American Public

Reuters - US Online Video (July 22, 2014) Ten years after releasing its initial report, members of the 9/11 Commission warn of the "waning sense of urgency" in combating terrorists attacks. Mana Rabiee reports. Video provided by Reuters
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:
from the past week

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