August 7, 2017 For the first time, scientists have conducted thermonuclear measurements of nuclear reaction cross-sections under extreme conditions like those of stellar interiors. Credit: Lawrence Livermore National Laboratory

Most of the nuclear reactions that drive the nucleosynthesis of the elements in our universe occur in very extreme stellar plasma conditions. This intense environment found in the deep interiors of stars has made it nearly impossible for scientists to perform nuclear measurements in these conditions - until now.

In a unique cross-disciplinary collaboration between the fields of plasma physics, nuclear astrophysics and laser fusion, a team of researchers including scientists from Lawrence Livermore National Laboratory (LLNL), Ohio University, the Massachusetts Institute of Technology (MIT) and Los Alamos National Laboratory (LANL), describe experiments performed in conditions like those of stellar interiors. The team's findings were published today by Nature Physics.

The experiments are the first thermonuclear measurements of nuclear reaction cross-sections - a quantity that describes the probability that reactants will undergo a fusion reaction - in high-energy-density plasma conditions that are equivalent to the burning cores of giant stars, i.e. 10-40 times more massive than the sun. These extreme plasma conditions boast hydrogen-isotope densities compressed by a factor of a thousand to near that of solid lead and temperatures heated to ~50 million Kelvin. These also are the conditions in stars that lead to supernovae, the most massive explosions in the universe.

"Ordinarily, these kinds of nuclear astrophysics experiments are performed on accelerator experiments in the laboratory, which become particularly challenging at the low energies often relevant for nucleosynthesis," said LLNL physicist Dan Casey, the lead author on the paper. "As the reaction cross-sections fall rapidly with decreasing reactant energy, bound electron screening corrections become significant, and terrestrial and cosmic background sources become a major experimental challenge."

The work was conducted at LLNL's National Ignition Facility (NIF), the only experimental tool in the world capable of creating temperatures and pressures like those found in the cores of stars and giant planets. Using the indirect drive approach, NIF was used to drive a gas-filled capsule implosion, heating capsules to extraordinary temperatures and compressing them to high densities where fusion reactions can occur.

"One of the most important findings is that we reproduced prior measurements made on accelerators in radically different conditions," Casey said. "This really establishes a new tool in the nuclear astrophysics field for studying various processes and reactions that may be difficult to access any other way."

"Perhaps most importantly, this work lays groundwork for potential experimental tests of phenomena that can only be found in the extreme plasma conditions of stellar interiors. One example is of plasma electron screening, a process that is important in nucleosynthesis but has not been observed experimentally," Casey added.

Now that the team has established a technique to perform these measurements, related teams like that led by Maria Gatu Johnson at MIT are looking to explore other nuclear reactions and ways to attempt to measure the impact of plasma electrons on the nuclear reactions.

Explore further: How heavier elements are formed in star interiors

More information: D. T. Casey et al. Thermonuclear reactions probed at stellar-core conditions with laser-based inertial-confinement fusion, Nature Physics (2017). DOI: 10.1038/nphys4220

When the renowned cosmologist Carl Sagan declared that "we are made of starstuff," he wasn't speaking metaphorically. As Sagan said in the TV series "Cosmos," many of the elements in our bodies - "the nitrogen in our DNA, ...

Nuclear astrophysicists successfully created the first low-energy particle accelerator beam deep underground in the United States, bringing them one step closer to understanding how the elements of our universe are built.

Determining the chemical abundance pattern left by the earliest stars in the universe is no easy feat. A Lawrence Livermore National Laboratory (LLNL) scientist is helping to do just that.

Turbulence, the violently unruly disturbance of plasma, can prevent plasma from growing hot enough to fuel fusion reactions. Long a puzzling concern of researchers has been the impact on turbulence of atoms recycled from ...

The energy production in stars utlimately depends on certain nuclear reactions at energies close to the so-called Gamow-peak that affect strongly the chemical composition of stars and the surrounding planetary systems. These ...

Two major issues confronting magnetic-confinement fusion energy are enabling the walls of devices that house fusion reactions to survive bombardment by energetic particles, and improving confinement of the plasma required ...

Most of the nuclear reactions that drive the nucleosynthesis of the elements in our universe occur in very extreme stellar plasma conditions. This intense environment found in the deep interiors of stars has made it nearly ...

New results show a difference in the way neutrinos and antineutrinos behave, which could help explain why there is so much matter in the universe.

Engineers at Stanford University and the University of California San Diego have developed a camera that generates four-dimensional images and can capture 138 degrees of information. The new camerathe first-ever single-lens, ...

A research team at the University of Central Florida has demonstrated the fastest light pulse ever developed, a 53-attosecond X-ray flash.

Air travel may be the quickest way to get to your vacation destination, but it's also one of the speediest ways for infectious diseases to spread between people, cities and countries.

(Phys.org)Quantum engines are known to operate differently thanand in some cases, outperformtheir classical counterparts. However, previous research on the performance of quantum engines may be overestimating their ...

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

View original post here:

Scientists probe the conditions of stellar interiors to measure nuclear reactions - Phys.Org