Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Nuclear Masses Measured to within a Hair’s Precision

06.05.2009
MSU researchers have made precise mass measurements of four such nuclei, 68-selenium, 70-selenium, 71-bromine and an excited state of 70-bromine. The results may make it easier to understand X-ray bursts, the most common stellar explosions in the galaxy.

No one likes to say exactly how much they weigh. Rare atomic nuclei are similarly coy, obviously not because of their own volition, but rather because they are exceedingly difficult to produce and, while they exist, very short-lived and difficult to corral and accurately measure.

Now, MSU researchers have made precise mass measurements of four such nuclei, 68-selenium, 70-selenium, 71-bromine and an excited state of 70-bromine (yes, a nucleus weighs measurably more when it is excited because of Einstein’s famous E=mc2 declaration). The results may make it easier to understand X-ray bursts, the most common stellar explosions in the galaxy.

X-ray bursts are spectacular runaway thermonuclear reactions on neutron stars that release vast amounts of energy in a short period of time. In just 10 seconds, an X-ray burst might release as much energy as our sun does in one month. Such explosions occur in binary systems where a neutron star and a second donor star orbit each other. The donor star rains hydrogen and helium onto the surface of the neutron star. When enough of this material accumulates, nuclear fusion reactions begin, dramatically increasing temperature to nearly 2 billion degrees Fahrenheit, which is about 10,000 times hotter than the surface of the sun. This temperature spike gives rise to the explosion and eventually to what’s known as the rapid proton capture nucleo-synthesis-process, or rp-process.

The rp-process occurs when a seed nucleus in a super-hot stellar environment begins capturing protons in quick succession, piling them up until the nucleus cannot hold any more. The nucleus then spits out some energy, turning a proton into a neutron, which allows the piling on to start anew.

The rp-process is roughly analogous to stacking blocks one after the other. Eventually the stack gets sufficiently tall and unsteady that the blocks fall into a more compact and stable jumble. If the stacking continues on top of this pile, eventually a new jumbled shape will be created when the blocks fall down a second time. In time, this repeated stacking and tumbling will create a slew of new increasingly larger piles, just as the successive capture and decay during the rp-process is thought to create many heavy elements, possibly up to tellurium, stable versions of which have 52 protons and anywhere from 70 to 74 neutrons.

The MSU team, including nuclear science doctoral student Josh Savory, were interested in four atomic nuclei because they represent a pause button of sorts during the rp-process. Normally the capture-decay sequence that creates new elements happens in a blink of an eye, in a matter of seconds or less. However it takes time, perhaps 30 seconds or more, for selenium-68 and a few similar nuclei to decay. It’s possible these waiting points can be bypassed if two protons are captured instead of one. Precise mass measurements help to refine theoretical models that explain whether or not these waiting points are bypassed and in general, just how fast nuclear reactions proceed during X-ray bursts. This information, in turn, helps researchers predict and explain just how much of each of the various elements are produced during the rp-process.

The experiment, conducted by Savory and several colleagues, used NSCL’s Low Energy Beam and Ion Trap facility, LEBIT, to make the mass measurements of the four nuclei. LEBIT uses a technique known as Penning trap mass spectrometry to perform these measurements. (A physics 101 aside: Weight and mass are often confused. Weight of matter is entirely dependent upon the strength of gravity while the mass of matter is constant. Someone who weighed 180 pounds on Earth would weigh just 30 pounds on the moon, which exerts a much more modest gravitational pull. That same person’s mass would be the same on Earth, the moon or, with few exceptions, anywhere in the universe. The equation is w (weight) = g (gravity) X m (mass)).

LEBIT takes isotope beams traveling at roughly half the speed of light and carefully slows and stops the isotopes for highly accurate mass measurement. MSU is home to the only physics lab in the world capable of performing such measurements on isotopes produced by fast beam fragmentation, a technique that allows for the production of extremely rare nuclei not normally found on Earth.

The MSU team measured the masses to a level of precision as high as 1 part per 100 million (for 68-selenium) and with an improved precision as large as 100 times (for 71-bromine) in comparison to previous such measurements.

“As an analogue, think of a scale precise enough to see how your weight changes when you pluck just one hair out of your head,” said Savory, lead author of a paper describing the results which appears in Physical Review Letters.

Geoff Koch | Newswise Science News
Further information:
http://www.nscl.msu.edu

More articles from Physics and Astronomy:

nachricht One-way roads for spin currents
23.05.2018 | Singapore University of Technology and Design

nachricht Tunable diamond string may hold key to quantum memory
23.05.2018 | Harvard John A. Paulson School of Engineering and Applied Sciences

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: LZH showcases laser material processing of tomorrow at the LASYS 2018

At the LASYS 2018, from June 5th to 7th, the Laser Zentrum Hannover e.V. (LZH) will be showcasing processes for the laser material processing of tomorrow in hall 4 at stand 4E75. With blown bomb shells the LZH will present first results of a research project on civil security.

At this year's LASYS, the LZH will exhibit light-based processes such as cutting, welding, ablation and structuring as well as additive manufacturing for...

Im Focus: Self-illuminating pixels for a new display generation

There are videos on the internet that can make one marvel at technology. For example, a smartphone is casually bent around the arm or a thin-film display is rolled in all directions and with almost every diameter. From the user's point of view, this looks fantastic. From a professional point of view, however, the question arises: Is that already possible?

At Display Week 2018, scientists from the Fraunhofer Institute for Applied Polymer Research IAP will be demonstrating today’s technological possibilities and...

Im Focus: Explanation for puzzling quantum oscillations has been found

So-called quantum many-body scars allow quantum systems to stay out of equilibrium much longer, explaining experiment | Study published in Nature Physics

Recently, researchers from Harvard and MIT succeeded in trapping a record 53 atoms and individually controlling their quantum state, realizing what is called a...

Im Focus: Dozens of binaries from Milky Way's globular clusters could be detectable by LISA

Next-generation gravitational wave detector in space will complement LIGO on Earth

The historic first detection of gravitational waves from colliding black holes far outside our galaxy opened a new window to understanding the universe. A...

Im Focus: Entangled atoms shine in unison

A team led by Austrian experimental physicist Rainer Blatt has succeeded in characterizing the quantum entanglement of two spatially separated atoms by observing their light emission. This fundamental demonstration could lead to the development of highly sensitive optical gradiometers for the precise measurement of the gravitational field or the earth's magnetic field.

The age of quantum technology has long been heralded. Decades of research into the quantum world have led to the development of methods that make it possible...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Save the date: Forum European Neuroscience – 07-11 July 2018 in Berlin, Germany

02.05.2018 | Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

 
Latest News

Research reveals how order first appears in liquid crystals

23.05.2018 | Life Sciences

Space-like gravity weakens biochemical signals in muscle formation

23.05.2018 | Life Sciences

NIST puts the optical microscope under the microscope to achieve atomic accuracy

23.05.2018 | Physics and Astronomy

VideoLinks
Science & Research
Overview of more VideoLinks >>>