Researchers move closer to switching nuclear isomer decay on and off

April 6, 2007

Livermore researchers have moved one step closer to being able to turn on and off the decay of a nuclear isomer.

The protons and neutrons in a nucleus can be arranged in many ways. The arrangement with the lowest energy is called the ground state and all others are called excited states. (This is analogous to the ground and excited states of electrons in an atom except that nuclear excited states are typically thousands of times higher in energy.) Excited nuclear states eventually decay to the ground state via gamma emission or to another nucleus via particle emission. Most excited states are short-lived (e.g., billionth of a second). However, a few are long-lived (e.g., hours) and are called isomers.

Turning the decay on and off is key to using isiomers as high-energy density storage systems such as batteries.

Researchers at Livermore studied an isomer of Thorium-229. This isomer is unique in that its excitation energy is near optical energies, implying that one day scientists may be able to transition Th229 nuclei between the ground and isomeric states using a table-top laser.

"This would then be the first time human control would be exerted over nuclear levels," said Peter Beiersdorfer, an LLNL physicist and co-author of a paper that appears in the April 6 issue of Physical Review Letters. "This only works if the laser is tuned to exactly the correct energy."

For years, researchers have been fascinated with this isomer because it could lead to new science and technology breakthroughs. Among them are: a quantum many-body study; a clock with unparallel precision for general relativity tests; a superb qubit (a quantum bit) for quantum computing; testing the effects of the chemical environment on nuclear decay rates. Isomers also may serve as a battery for storing large amounts of energy.

However, before these exotic studies can be performed, an accurate determination of the isomer’s excitation energy above the ground state is needed. In the most recent research, Livermore scientists, along with colleagues from Los Alamos National Laboratory and NASA Goddard Space Flight Center, have made the most accurate measurement of this energy difference using an indirect technique.

"Our measurement is more accurate and differs significantly from prior results. This may explain why scientists have failed to directly see this transition. Frankly, they were looking in the wrong place," said Bret Beck, an LLNL physicist and lead-author on the paper.

The next step will be to use a laser or a synchrotron tuned to the exact energy of the spacing between the two levels and observe the transition from the ground state to the isomeric state.

Once laser excitation has proven possible, helping an excited level decay (and thus give off energy) can be tackled. "But for building a more precise clock than we have today, or building a quantum computer, excitation may be all that’s needed," Beiersdofer said.

Source: Lawrence Livermore National Laboratory

Explore further: Fermi Space Telescope sharpens its high-energy vision

Related Stories

Fermi Space Telescope sharpens its high-energy vision

January 7, 2016

Major improvements to methods used to process observations from NASA's Fermi Gamma-ray Space Telescope have yielded an expanded, higher-quality set of data that allows astronomers to produce the most detailed census of the ...

Explore galaxies far, far away at internet speeds

January 21, 2016

No need for hyperdrive: Scientists have released an "expansion pack" for a virtual tour of the universe that you can enjoy from the comfort of your own computer. The latest version of the publicly accessible images of the ...

Some like it hot: Simulating single particle excitations

December 17, 2015

Plasmons, which may be thought of as clouds of electrons that oscillate within a metal nanocluster, could serve as antennae to absorb sunlight more efficiently than semiconductors. Understanding and manipulating them is important ...

New derivation of pi links quantum physics and pure math

November 10, 2015

In 1655 the English mathematician John Wallis published a book in which he derived a formula for pi as the product of an infinite series of ratios. Now researchers from the University of Rochester, in a surprise discovery, ...

NuSTAR finds clumpy doughnut around black hole

December 17, 2015

The most massive black holes in the universe are often encircled by thick doughnut-shaped disks of material. This doughnut material ultimately feeds and nourishes the growing black holes tucked inside. Until recently, some ...

Recommended for you

Scientists glimpse Einstein's gravitational waves (Update)

February 11, 2016

In a landmark discovery for physics and astronomy, scientists said Thursday they have glimpsed the first direct evidence of gravitational waves, ripples in the fabric of space-time that Albert Einstein predicted a century ...

Superconductors could detect superlight dark matter

February 9, 2016

(—Many experiments are currently searching for dark matter—the invisible substance that scientists know exists only from its gravitational effect on stars, galaxies, and other objects made of ordinary matter. ...

A 'magical' space-time ripple that wasn't believed, at first

February 11, 2016

The wave that made history snuck up on them. David Shoemaker will never forget the date—September 14, 2015—when he woke up to a message alerting him that an underground detector had spotted a 1.3-billion-year-old ripple ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.