Exotic atoms hold clues to unsolved physics puzzle at the dawn of the universe

May 08, 2013
Exotic atoms hold clues to unsolved physics puzzle at the dawn of the universe
Graphical representation of the shapes of 220Rn and 224Ra. Credit: Nature, doi:10.1038/nature12073

An international team of physicists has found the first direct evidence of pear shaped nuclei in exotic atoms. The findings could advance the search for a new fundamental force in nature that could explain why the Big Bang created more matter than antimatter—-a pivotal imbalance in the history of everything.

"If equal amounts of matter and antimatter were created at the , everything would have annihilated, and there would be no galaxies, stars, planets or people," said Tim Chupp, a University of Michigan professor of physics and biomedical engineering and co-author of a paper on the work published in the May 9 issue of Nature.

have the same mass but opposite charge from their matter counterparts. Antimatter is rare in the known universe, flitting briefly in and out of existence in , and like CERN's , for example. When they find each other, matter and antimatter particles mutually destruct or annihilate.

What caused the matter/antimatter imbalance is one of physics' great mysteries. It's not predicted by the Standard Model—-the overarching theory that describes the and the nature of matter.

The Standard Model describes four fundamental forces or interactions that govern how matter behaves: Gravity attracts massive bodies to one another. The gives rise to forces on electrically charged bodies. And the strong and weak forces operate in the cores of atoms, binding together neutrons and protons or causing those particles to decay.

Physicists have been searching for signs of a new force or interaction that might explain the matter-antimatter discrepancy. The evidence of its existence would be revealed by measuring how the axis of nuclei of the radon and radium line up with the spin.

The researchers confirmed that the cores of these atoms are shaped like pears, rather than the more typical spherical orange or elliptical watermelon profiles. The pear shape makes the effects of the new interaction much stronger and easier to detect.

"The pear shape is special," Chupp said. "It means the neutrons and protons, which compose the nucleus, are in slightly different places along an internal axis."

The pear-shaped nuclei are lopsided because positive protons are pushed away from the center of the nucleus by nuclear forces, which are fundamentally different from spherically symmetric forces like gravity.

A graphical representation of the pear-shaped nucleus of an exotic atom. The shape of the nucleus could give clues to why the universe contains more matter than antimatter. Image credit: Liam Gaffney and Peter Butler, University of Liverpool

"The new interaction, whose effects we are studying does two things," Chupp said. "It produces the matter/antimatter asymmetry in the early universe and it aligns the direction of the spin and the charge axis in these pear-shaped nuclei."

To determine the shape of the nuclei, the researchers produced beams of exotic—-short- lived—-radium and radon atoms at 's Isotope Separator facility ISOLDE. The atom beams were accelerated and smashed into targets of nickel, cadmium and tin, but due to the repulsive force between the positively charged nuclei, nuclear reactions were not possible. Instead, the nuclei were excited to higher energy levels, producing gamma rays that flew out in a specific pattern that revealed the pear shape of the nucleus.

"In the very biggest picture, we're trying to understand everything we've observed directly and also indirectly, and how it is that we happen to be here," Chupp said.

The research was led by University of Liverpool Physics Professor Peter Butler.

"Our findings contradict some nuclear theories and will help refine others," he said.

The measurements also will help direct the searches for atomic EDMs (electric dipole moments) currently being carried out in North America and Europe, where new techniques are being developed to exploit the special properties of radon and radium isotopes.

"Our expectation is that the data from our nuclear physics experiments can be combined with the results from atomic trapping experiments measuring EDMs to make the most stringent tests of the , the best theory we have for understanding the nature of the building blocks of the universe," Butler said.

Explore further: How cloud chambers revealed subatomic particles

More information: The paper is titled "Studies of nuclear pear-shapes using accelerated radioactive beams." www.nature.com/nature/journal/… ull/nature12073.html

Related Stories

Team maps the nuclear landscape

Jun 27, 2012

An Oak Ridge National Laboratory and University of Tennessee team has used the Department of Energy's Jaguar supercomputer to calculate the number of isotopes allowed by the laws of physics.

UBC physicists make atoms and dark matter add up

Nov 29, 2010

Physicists at the University of British Columbia and TRIUMF have proposed a unified explanation for dark matter and the so-called baryon asymmetry -- the apparent imbalance of matter with positive baryon charge and antimatter ...

Recommended for you

How cloud chambers revealed subatomic particles

15 hours ago

Atoms are made of electrons, protons and neutrons. Protons and neutrons are in turn made up of quarks. These are just some of the elementary particles that make up the foundation of modern particle physics. ...

When a doughnut becomes an apple

16 hours ago

In experiments using the wonder material graphene, ETH researchers have been able to demonstrate a phenomenon predicted by a Russian physicist more than 50 years ago. They analyzed a layer structure that ...

Uncovering the forbidden side of molecules

Sep 21, 2014

Researchers at the University of Basel in Switzerland have succeeded in observing the "forbidden" infrared spectrum of a charged molecule for the first time. These extremely weak spectra offer perspectives ...

User comments : 9

Adjust slider to filter visible comments by rank

Display comments: newest first

vacuum-mechanics
1 / 5 (14) May 08, 2013
Antimatter particles have the same mass but opposite charge from their matter counterparts. Antimatter is rare in the known universe, flitting briefly in and out of existence in cosmic rays, solar flares and particle accelerators like CERN's Large Hadron Collider, for example. When they find each other, matter and antimatter particles mutually destruct or annihilate.

Maybe what we called antimatter particle (such as positron) was misinterpreted as a real particle like a true stable electron! Understanding how electron was create and how matter was formed could help to solve the problem as follow…
http://www.vacuum...=9〈=en
Q-Star
4.3 / 5 (17) May 08, 2013
Maybe what we called antimatter particle (such as positron) was misinterpreted as a real particle like a true stable electron!


Naaa, it interpreted properly, it's a real particle. The first real one was isolated in 1937, a Nobel Prize was awarded for that. We see them all the time as result of cosmic rays. They are created at will every day in PET scanners found in most large medical centers. We've been producing the real positrons in accelerators for six decades now.

Understanding how electron was create and how matter was formed could help to solve the problem as follow


Uuh,,, Duh. That is what the article is about.

When was the last time "vacuum-mechanical imaging" was done at a medical center?

By the By: We can also create electrons at will in accelerators. Have ya seen one of the old time electron ray tube televisions, how does the "vacuum-mechanical tube" compare for picture quality,,, I've not had the pleasure of watching one yet meself.
EyeNStein
1 / 5 (4) May 09, 2013
This article lacks any substantial detail about this "new force" or its supposed link to matter anti-matter imbalance.
What feature of this "pear shape" distinguishes it from a nucleus, as currently modelled, simply close to the edge of flying apart when the electrical repulsion overcomes the strong force and causes fission?
ValeriaT
1 / 5 (1) May 09, 2013
CP-invariance manifests itself with preferential decay of Co-60 nuclei in one direction and it's handled well with Standard Model. The problem of Standard Model rather is, why QCD doesn't violate the CP-symmetry too - i.e. the exactly the opposite problem. So I don't think, the asymmetry of atom nuclei is directly related to matter-antimatter asymmetry.
gwrede
1 / 5 (1) May 10, 2013
I wouldn't be surprised if it turned out that all nuclei (except for hydrogen, of course) turn out to be non-spherical if you take a good look.
ValeriaT
not rated yet May 11, 2013
Of course, many atom nuclei were already found unsymmetrical.
Moebius
1 / 5 (1) May 12, 2013
"If equal amounts of matter and antimatter were created at the Big Bang, everything would have annihilated..."

That sounds like BS to me. We can't even make that happen on a small scale mixing 2 things in exact amounts (like oxygen and hydrogen). Nothing perfectly interacts like that.

NikFromNYC
1 / 5 (2) May 15, 2013
Big Bang theory is crazy since except by violating its own basis as spontaneous generation from nothing do you end up with something that doesn't just implode back to nothing, except a bunch of light with nowhere to call home since all the matter is gone. But all that light still exists as positive energy, right, so that's not something from nothing is it?
antialias_physorg
not rated yet May 15, 2013
do you end up with something that doesn't just implode back to nothing,

Not with inflation. If the Big Bang were an explosion INTO space (as you erroneously assume) you'd be right.
But it was an inflation OF space. And if space inflates faster than stuff can move then it doesn't implode.

That sounds like BS to me. We can't even make that happen on a small scale mixing 2 things

That always bugged me, too.
However, if you don't get perfect mixing we should get pockets of matter and pockets of antimatter (and pretty fireworks when the occasional matter and antimatter galaxies collide - an we don't see that. ). So it does look like there is an imbalance in favor of matter over antimatter

(or more antimatter than matter. In which case we're in a VERY lucky matter galaxy surrounded by mostly antimatter and it'll be 'interesting' when Andromeda crashes into us).