Featured Research

from universities, journals, and other organizations

Measurements hint why the universe is dominated by matter, not anti-matter

Date:
December 26, 2012
Source:
University of Wisconsin-Madison
Summary:
Physicists have made a precise measurement of elusive, nearly massless particles, and obtained a crucial hint as to why the universe is dominated by matter, not by its close relative, anti-matter.

A pool holding four anti-neutrino detectors begins filling with ultra-pure water in September, 2012 at the Daya Bay Neutrino experiment. The experiment, just recognized by Science magazine as a breakthrough of the year, is helping to explain why the universe contains virtually no anti-matter. University of Wisconsin-Madison physicist Karsten Heeger and Physical Sciences Laboratory engineer Jeff Cherwinka both played major roles at the experiment.
Credit: Roy Kaltschmidt, Lawrence Berkeley National Laboratory

A collaboration with major participation by physicists at the University of Wisconsin-Madison has made a precise measurement of elusive, nearly massless particles, and obtained a crucial hint as to why the universe is dominated by matter, not by its close relative, anti-matter.

Related Articles


The particles, called anti-neutrinos, were detected at the underground Daya Bay experiment, located near a nuclear reactor in China, 55 kilometers north of Hong Kong. For the measurement of anti-neutrinos it made in 2012, the Daya Bay collaboration has been named runner-up for breakthrough of the year from Science magazine.

Anti-particles are almost identical twins of sub-atomic particles (electrons, protons and neutrons) that make up our world. When an electron encounters an anti-electron, for example, both are annihilated in a burst of energy. Failure to see these bursts in the universe tells physicists that anti-matter is vanishingly rare, and that matter rules the roost in today's universe.

"At the beginning of time, in the Big Bang, a soup of particles and anti-particles was created, but somehow an imbalance came about," says Karsten Heeger, a professor of physics at UW-Madison. "All the studies that have been done have not found enough difference between particles and anti-particles to explain the dominance of matter over anti-matter."

But the neutrino, an extremely abundant but almost massless particle, may have the right properties, and may even be its own anti-particle, Heeger says. "And that's why physicists have put their last hope on the neutrino to explain the absence of anti-matter in the universe."

Heeger and his group at UW-Madison have been responsible for much of the design and development of the anti-neutrino detectors at Daya Bay. Jeff Cherwinka, from the university's Physical Sciences Laboratory in Stoughton, Wis. is chief engineer of the experiment and has overseen much of the detector assembly and installation. The construction of the experiment was completed this fall and data-taking started in October using the full set of anti-neutrino detectors.

Reactors, Heeger says, are a fertile source of anti-neutrinos, and measuring how they change during their short flights from the reactor to the detector, gives a basis for calculating a quantity called the "mixing angle," the probability of transformation from one flavor into another.

The measurement of the Daya Bay experiment, released in March 2012, even before the last set of detectors was installed, showed a surprisingly large angle, Heeger says. "People thought the angle might be really tiny, so we built an experiment that was 10 times as sensitive as we ended up needing.

"The neutrino community has been waiting for a long time for this parameter, which will be used for planning experiments for next decade and beyond," says Heeger, "and that is why it was recognized by Science."

As expected, Science's breakthrough of the year was the detection of the Higgs boson, an elusive sub-atomic particle that completes the "particle zoo" predicted by the standard model of physics. That discovery also had major participation by physicists from the UW-Madison.


Story Source:

The above story is based on materials provided by University of Wisconsin-Madison. The original article was written by David Tenenbaum. Note: Materials may be edited for content and length.


Cite This Page:

University of Wisconsin-Madison. "Measurements hint why the universe is dominated by matter, not anti-matter." ScienceDaily. ScienceDaily, 26 December 2012. <www.sciencedaily.com/releases/2012/12/121226153024.htm>.
University of Wisconsin-Madison. (2012, December 26). Measurements hint why the universe is dominated by matter, not anti-matter. ScienceDaily. Retrieved December 17, 2014 from www.sciencedaily.com/releases/2012/12/121226153024.htm
University of Wisconsin-Madison. "Measurements hint why the universe is dominated by matter, not anti-matter." ScienceDaily. www.sciencedaily.com/releases/2012/12/121226153024.htm (accessed December 17, 2014).

Share This


More From ScienceDaily



More Matter & Energy News

Wednesday, December 17, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

How Sony Hopes To Make Any Glasses 'Smart'

How Sony Hopes To Make Any Glasses 'Smart'

Newsy (Dec. 17, 2014) Sony's glasses module attaches to the temples of various eye- and sunglasses to add a display and wireless connectivity. Video provided by Newsy
Powered by NewsLook.com
Los Angeles Police To Receive 7,000 Body Cameras

Los Angeles Police To Receive 7,000 Body Cameras

Newsy (Dec. 17, 2014) Los Angeles Mayor Eric Garcetti announced the cameras will be distributed starting Jan. 1. Video provided by Newsy
Powered by NewsLook.com
Jaguar Unveils 360 Virtual Windshield Making Car Pillars Appear Transparent

Jaguar Unveils 360 Virtual Windshield Making Car Pillars Appear Transparent

Buzz60 (Dec. 17, 2014) Jaguar unveils a virtual 360 degree windshield that may be the most futuristic automotive development yet. Jen Markham explains. Video provided by Buzz60
Powered by NewsLook.com
Researchers Bring Player Pianos Back to Life

Researchers Bring Player Pianos Back to Life

AP (Dec. 17, 2014) Stanford University wants to unlock the secrets of the player piano. Researchers are restoring and studying self-playing pianos and the music rolls that recorded major composers performing their own work. (Dec. 17) Video provided by AP
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