Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


MSU researchers lead team that observes exotic radioactive decay process


Researchers from the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU) and TRIUMF (Canada's national particle accelerator) have observed a rare nuclear decay. Namely, the team measured low-kinetic-energy protons emitted after the beta decay of a neutron-rich nucleus beryllium-11. The research team presented their results in an article recently published in Physical Review Letters.

An atomic nucleus with many more neutrons than protons is neutron-rich and unstable. It will get rid of excess neutrons to become stable through the beta-decay process. Beta decay is common in atomic nuclei. In this process, the nucleus emits a beta particle and transforms a neutron into a proton, or a proton into a neutron.

This is an artist's depiction of the beta-delayed proton emission of beryllium-11 measured with the Active Target Time Projection Chamber. The proton track is indicated.

Credit: National Superconducting Cyclotron Laboratory

Yassid Ayyad, detector systems physicist at the National Superconducting Cyclotron Laboratory at Michigan State University, is part of the research team that observed a rare decay in the exotic beryllium-11 nucleus. Here he holds the pad plane of the Active Target Time Projection Chamber detector that was used in the experiment.

Credit: National Superconducting Cyclotron Laboratory

Less common is proton emission following beta decay of a neutron-rich nucleus. Beta-delayed proton emission, observed more than 40 years ago, typically occurs in proton-rich nuclei.

For neutron-laden nuclei, it defies laws of energy to emit protons after beta decay unless the neutrons are loosely bound and essentially free. This condition may be fulfilled in so-called halo nuclei, where one or two neutrons orbit the remaining core at a considerable distance.

"There are few neutron-rich nuclei for which the elusive proton emission following beta decay can happen," said Yassid Ayyad, detector systems physicist at NSCL, who is part of the research team that observed the rare decay.

"Beryllium-11 is the most promising one. It becomes beryllium-10 after beta decay to boron-11 and the subsequent proton emission. The exotic radioactive decay we observed represents a new challenge for the understanding of exotic nuclei, in particular for halo nuclei."

According to experiments at the Isotope mass Separator On-Line (ISOLDE) facility at the European Organization for Nuclear Research (CERN) and the Vienna Environmental Research Accelerator (VERA) facility in Vienna, the probability of the beta-delayed proton emission in a neutron-rich nucleus is unexpectedly high.

Researchers did not directly observe protons coming from the beryllium-11 decay. This has led to speculations involving an extremely exotic decay. Instead of emitting a proton, the halo neutron would be transformed into an undetectable dark-matter particle.

Dark matter is an unseen hypothetical substance. It may consist of exotic particles that do not interact with normal matter or light but still exert a gravitational pull.

Ayyad emphasized the significance of this speculation. "This scenario, if confirmed, would represent the first indirect observation of dark matter," he said.

The ISOLDE/VERA team suggested another, less exotic, explanation of the high decay rate. It involves a narrow resonance in boron-11 close to the energy threshold where the nucleus is allowed to emit a proton. This scenario is reminiscent of the discovery of the Hoyle state, an excited state of carbon-12 that is very close to the alpha-particle separation energy, the energy threshold about which the nucleus can emit an alpha particle (helium-4). Astronomer Fred Hoyle first proposed this state in 1954 to explain the production of carbon in stars.

"One of the most exciting outcomes of this work is that the proton emission proceeds through a highly-excited, narrow resonance state in the boron-11 nucleus," Ayyad said, thus confirming the "Hoyle-like" scenario involving the threshold resonance.

The team used the Active Target Time Projection Chamber (AT-TPC) developed at NSCL to perform the experiment. This gas-filled detector has a very large detection probability and provides the energy of the particle with high accuracy and precision. The detector delivers a three-dimensional image of the charged particles emitted in the beryllium-11 decay, including information about their energy. The TRIUMF Isotope Separator and Accelerator facility delivered a beryllium-11 beam. Experimenters implanted the beam in the middle of the detector to capture its decay modes. The beryllium-11 decayed into beryllium-10 and a proton, with a narrow energy distribution only 0.0013 percent of the time. The beryllium-10, together with the decay proton, is thought to form a boron-11 nucleus with high-excitation energy that exists during a brief period of time.

This research is of interest for future studies. The AT-TPC and the intense rare-isotope beams provided by the Facility for Rare Isotope Beams (FRIB) at MSU will make it feasible to characterize this new resonance and find other, more exotic particle emitters.


The National Science Foundation's National Superconducting Cyclotron Laboratory is a center for nuclear and accelerator science research and education. It is the nation's premier scientific user facility dedicated to the production and study of rare isotopes.

MSU is establishing FRIB as a new scientific user facility for the Office of Nuclear Physics in the U.S. Department of Energy Office of Science. Under construction on campus and operated by MSU, FRIB will enable scientists to make discoveries about the properties of rare isotopes in order to better understand the physics of nuclei, nuclear astrophysics, fundamental interactions, and applications for society, including in medicine, homeland security and industry.

Media Contact

Karen King

Karen King | EurekAlert!
Further information:

Further reports about: Accelerator Beams MSU NSCL detector isotopes nuclei radioactive decay

More articles from Physics and Astronomy:

nachricht Double layer of graphene helps to control spin currents
18.10.2019 | University of Groningen

nachricht Analysis of Galileo's Jupiter entry probe reveals gaps in heat shield modeling
17.10.2019 | American Institute of Physics

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: Solving the mystery of quantum light in thin layers

A very special kind of light is emitted by tungsten diselenide layers. The reason for this has been unclear. Now an explanation has been found at TU Wien (Vienna)

It is an exotic phenomenon that nobody was able to explain for years: when energy is supplied to a thin layer of the material tungsten diselenide, it begins to...

Im Focus: An ultrafast glimpse of the photochemistry of the atmosphere

Researchers at Ludwig-Maximilians-Universitaet (LMU) in Munich have explored the initial consequences of the interaction of light with molecules on the surface of nanoscopic aerosols.

The nanocosmos is constantly in motion. All natural processes are ultimately determined by the interplay between radiation and matter. Light strikes particles...

Im Focus: Shaping nanoparticles for improved quantum information technology

Particles that are mere nanometers in size are at the forefront of scientific research today. They come in many different shapes: rods, spheres, cubes, vesicles, S-shaped worms and even donut-like rings. What makes them worthy of scientific study is that, being so tiny, they exhibit quantum mechanical properties not possible with larger objects.

Researchers at the Center for Nanoscale Materials (CNM), a U.S. Department of Energy (DOE) Office of Science User Facility located at DOE's Argonne National...

Im Focus: Novel Material for Shipbuilding

A new research project at the TH Mittelhessen focusses on the development of a novel light weight design concept for leisure boats and yachts. Professor Stephan Marzi from the THM Institute of Mechanics and Materials collaborates with Krake Catamarane, which is a shipyard located in Apolda, Thuringia.

The project is set up in an international cooperation with Professor Anders Biel from Karlstad University in Sweden and the Swedish company Lamera from...

Im Focus: Controlling superconducting regions within an exotic metal

Superconductivity has fascinated scientists for many years since it offers the potential to revolutionize current technologies. Materials only become superconductors - meaning that electrons can travel in them with no resistance - at very low temperatures. These days, this unique zero resistance superconductivity is commonly found in a number of technologies, such as magnetic resonance imaging (MRI).

Future technologies, however, will harness the total synchrony of electronic behavior in superconductors - a property called the phase. There is currently a...

All Focus news of the innovation-report >>>



Industry & Economy
Event News

International Symposium on Functional Materials for Electrolysis, Fuel Cells and Metal-Air Batteries

02.10.2019 | Event News

NEXUS 2020: Relationships Between Architecture and Mathematics

02.10.2019 | Event News

Optical Technologies: International Symposium „Future Optics“ in Hannover

19.09.2019 | Event News

Latest News

Energy Flow in the Nano Range

18.10.2019 | Power and Electrical Engineering

MR-compatible Ultrasound System for the Therapeutic Application of Ultrasound

18.10.2019 | Medical Engineering

Double layer of graphene helps to control spin currents

18.10.2019 | Physics and Astronomy

Science & Research
Overview of more VideoLinks >>>