Spallation Neutron Source sends first neutrons to 'Big Bang' beam line

Oct 09, 2008
While most of the instruments at the Spallation Neutron Source are dedicated to materials and condensed-matter studies, the Fundamental Neutron Physics Beam Line will explore questions in nuclear physics. Credit: ORNL photo

New analytical tools coming on line at the Spallation Neutron Source, the Department of Energy's state-of-the-art neutron science facility at Oak Ridge National Laboratory, include a beam line dedicated to nuclear physics studies.

The Fundamental Neutron Physics Beam Line (FNPB) has opened its shutter to receive neutrons for the first time. Among the nuclear physics studies planned for the new, intense beam line are experiments that probe the neutron-related mysteries associated with the "Big Bang."

"Completion of the Fundamental Neutron Physics Beam Line marks a significant step in the SNS's ramp up to full power, building up to its eventual suite of 25 instruments for neutron analysis," said ORNL Director Thom Mason, who led the SNS construction project to its completion. "The nuclear physics community is excited to have this new tool for exploring theories of the origins of the universe."

Although research at most of the current and future operating SNS beam lines is directed towards condensed matter and materials research, research at the FNPB is focused on basic studies in nuclear physics.

"While other beam lines use neutrons as a probe to study materials, the object for much of the work proposed at the FNPB is the study of the neutron itself," said University of Tennessee Professor Geoffrey Greene, who holds a Joint Faculty Appointment with ORNL and who leads the FNPB project. "Among the questions that will be addressed at the FNPB are the details of the internal structure of the neutron as well as a careful study of the way in which the free neutron decays. Such experiments have important implication for fundamental questions in particle physics and cosmology."

Greene explained that neutrons, which have no electric charge, may nevertheless have a slight displacement between internal positive and negative charges. The existence of such a "neutron electric dipole moment" could shed light on what happened in the early phases of the Big Bang. In particular it could help to explain why the universe appears to be made entirely of matter without any antimatter, he said.

While the neutron is stable in most nuclei, when it is liberated (for example in an SNS neutron beam) it lives for only about 10 minutes. "Precise measurements of the neutron lifetime help clarify the distribution of chemical elements generated in the first few minutes of the Big Bang and shed light on the amount of normal matter—as opposed to dark matter and dark energy—in the universe," Greene said.

"Another set of extremely precise studies at the FNPB will address the interaction between neutrons and simple nuclei and may help to explain universal 'parity' violation," Greene said. "Roughly speaking, parity is the symmetry that implies that the laws of physics are invariant when 'viewed in a mirror.' The surprising fact is, at a basic level, the universe appears to be 'left-handed.'

"The challenge remains to understand why this puzzling state of affairs exists," he said.

Greene noted that the theoretical basis for such symmetry violation --first outlined several decades ago--was recognized earlier this month with the 2008 Nobel Prize to Yoichiro Nambu.

Source: Oak Ridge National Laboratory

Explore further: New filter could advance terahertz data transmission

add to favorites email to friend print save as pdf

Related Stories

'Seeing' hydrogen atoms to unveil enzyme catalysis

Jan 08, 2015

(Phys.org) —Enzymes are catalysts that speed up chemical reactions in living organisms and control many cellular biological processes by converting a molecule, or substrate, into a product used by the cell. ...

Recommended for you

New filter could advance terahertz data transmission

Feb 27, 2015

University of Utah engineers have discovered a new approach for designing filters capable of separating different frequencies in the terahertz spectrum, the next generation of communications bandwidth that ...

The super-resolution revolution

Feb 27, 2015

Cambridge scientists are part of a resolution revolution. Building powerful instruments that shatter the physical limits of optical microscopy, they are beginning to watch molecular processes as they happen, ...

A new X-ray microscope for nanoscale imaging

Feb 27, 2015

Delivering the capability to image nanostructures and chemical reactions down to nanometer resolution requires a new class of x-ray microscope that can perform precision microscopy experiments using ultra-bright ...

Top-precision optical atomic clock starts ticking

Feb 26, 2015

A state-of-the-art optical atomic clock, collaboratively developed by scientists from the University of Warsaw, Jagiellonian University, and Nicolaus Copernicus University, is now "ticking away" at the National ...

User comments : 0

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.