Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Smile, protons, you're on camera

13.11.2007
Radioactivity, discovered more than 100 years ago and studied by physicists ever since, would seem to be a relatively closed subject in science. However, since the 1960s, the pursuit of at least one open question about how nuclei spontaneously eject various particles has continued to nag experimentalists, largely because of an inability to make precise measurements of fleeting, exotic nuclei.

In a paper published this week in Physical Review Letters, an international collaboration of researchers, led by Marek Pfutzner, a physicist from Warsaw University in Poland, takes several steps toward an answer. The scientists describe a first-ever success in peering closely at radioactive decay of a rare iron isotope at the ragged edge of the known nuclear map. The tools used to achieve this result include a novel combination of advanced physics equipment and imaging technology that is found in most off-the-shelf digital cameras.

"We have proved in a direct and clear way that this extremely neutron-deficient nucleus disintegrates by the simultaneous emission of two protons," write the authors.

Pfutzner and his collaborators set out to better understand an exotic form of radioactivity -- two-proton emissions from iron-45, a nucleus with 26 protons and 19 neutrons. The stable form of iron that is most abundant on Earth has 26 protons and 30 neutrons. One possibility was that the iron-45 isotope might occasionally release an energetically linked two-proton pair, known as a diproton. Other possibilities were that the protons, whether emitted in quick succession or simultaneously, were unlinked.

The research was performed at Michigan State University's National Superconducting Cyclotron Laboratory (NSCL), but the key device was a detector built by Pfutzner and his Warsaw University colleagues. Though nicknamed "the cannon" because of its vague resemblance to some sort of space age military device, the detector didn't shoot anything but rather was the target for the beam of rare isotopes produced at the NSCL Coupled Cyclotron Facility.

The detector included a front-end gas chamber that accepted and then slowed rare isotopes traveling at half the speed of light. The back-end imaging system, built around a high-end digital camera with standard charge-coupled device, or CCD, technology, recorded ghostly images of trajectories of emitted protons from the decaying iron-45 nuclei shot into the cannon's mouth.

Analysis of these images ruled out the theorized diproton emission and indicated that the observed correlations between emitted protons were best described by a form of nuclear transformation known as three-body decay. A theory of this process had previously been described by Leonid Grigorenko, a physicist at the Joint Institute for Nuclear Research in Dubna, Russia and a coauthor of the paper.

"There is amazing agreement between the experiment and Grigorenko's theory, which takes into account the complex interplay between emitted pairs of protons and the daughter nucleus," said Robert Grzywacz, a physicist at the University of Tennessee and Oak Ridge National Laboratory and a coauthor of the paper.

Besides shedding light on a novel form of radioactive decay, the technique also could lead to additional discoveries about fleeting, rare isotopes studied at accelerator facilities such as NSCL and Oak Ridge National Laboratory. These isotopes may hold the key to understanding processes inside neutron stars and determining the limits of nuclear existence.

The experiment itself also harkens back to the early days of experimental nuclear physics in which visual information served as the raw data. Before the days of cameras, this information was usually captured by scientists hunched over a microscope counting, for example, tiny flashes as alpha particles struck a zinc sulfide screen under the lens.

"It's perhaps the first time in modern nuclear physics that fundamentally new information about radioactive decay was captured in a picture taken by a digital camera," said Andreas Stolz, NSCL assistant professor and a coauthor on the paper. "Usually, in nuclear physics experiments you have digitized data and several channels of information from electronics equipment, but never images."

Geoff Koch | EurekAlert!
Further information:
http://www.phys.utk.edu/expnuclear/2p_reshigh.html
http://www.msu.edu

More articles from Physics and Astronomy:

nachricht Climate cycles may explain how running water carved Mars' surface features
02.12.2016 | Penn State

nachricht What do Netflix, Google and planetary systems have in common?
02.12.2016 | University of Toronto

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: Novel silicon etching technique crafts 3-D gradient refractive index micro-optics

A multi-institutional research collaboration has created a novel approach for fabricating three-dimensional micro-optics through the shape-defined formation of porous silicon (PSi), with broad impacts in integrated optoelectronics, imaging, and photovoltaics.

Working with colleagues at Stanford and The Dow Chemical Company, researchers at the University of Illinois at Urbana-Champaign fabricated 3-D birefringent...

Im Focus: Quantum Particles Form Droplets

In experiments with magnetic atoms conducted at extremely low temperatures, scientists have demonstrated a unique phase of matter: The atoms form a new type of quantum liquid or quantum droplet state. These so called quantum droplets may preserve their form in absence of external confinement because of quantum effects. The joint team of experimental physicists from Innsbruck and theoretical physicists from Hannover report on their findings in the journal Physical Review X.

“Our Quantum droplets are in the gas phase but they still drop like a rock,” explains experimental physicist Francesca Ferlaino when talking about the...

Im Focus: MADMAX: Max Planck Institute for Physics takes up axion research

The Max Planck Institute for Physics (MPP) is opening up a new research field. A workshop from November 21 - 22, 2016 will mark the start of activities for an innovative axion experiment. Axions are still only purely hypothetical particles. Their detection could solve two fundamental problems in particle physics: What dark matter consists of and why it has not yet been possible to directly observe a CP violation for the strong interaction.

The “MADMAX” project is the MPP’s commitment to axion research. Axions are so far only a theoretical prediction and are difficult to detect: on the one hand,...

Im Focus: Molecules change shape when wet

Broadband rotational spectroscopy unravels structural reshaping of isolated molecules in the gas phase to accommodate water

In two recent publications in the Journal of Chemical Physics and in the Journal of Physical Chemistry Letters, researchers around Melanie Schnell from the Max...

Im Focus: Fraunhofer ISE Develops Highly Compact, High Frequency DC/DC Converter for Aviation

The efficiency of power electronic systems is not solely dependent on electrical efficiency but also on weight, for example, in mobile systems. When the weight of relevant components and devices in airplanes, for instance, is reduced, fuel savings can be achieved and correspondingly greenhouse gas emissions decreased. New materials and components based on gallium nitride (GaN) can help to reduce weight and increase the efficiency. With these new materials, power electronic switches can be operated at higher switching frequency, resulting in higher power density and lower material costs.

Researchers at the Fraunhofer Institute for Solar Energy Systems ISE together with partners have investigated how these materials can be used to make power...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

ICTM Conference 2017: Production technology for turbomachine manufacturing of the future

16.11.2016 | Event News

Innovation Day Laser Technology – Laser Additive Manufacturing

01.11.2016 | Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

 
Latest News

UTSA study describes new minimally invasive device to treat cancer and other illnesses

02.12.2016 | Medical Engineering

Plasma-zapping process could yield trans fat-free soybean oil product

02.12.2016 | Agricultural and Forestry Science

What do Netflix, Google and planetary systems have in common?

02.12.2016 | Physics and Astronomy

VideoLinks
B2B-VideoLinks
More VideoLinks >>>