Nav: Home

UT-ORNL team makes first particle accelerator beam measurement in six dimensions

August 10, 2018

OAK RIDGE, Tenn., Aug.10, 2018 -- The first full characterization measurement of an accelerator beam in six dimensions will advance the understanding and performance of current and planned accelerators around the world.

A team of researchers led by the University of Tennessee, Knoxville conducted the measurement in a beam test facility at the Department of Energy's Oak Ridge National Laboratory using a replica of the Spallation Neutron Source's linear accelerator, or linac. The details are published in the journal Physical Review Letters.

"Our goal is to better understand the physics of the beam so that we can improve how accelerators operate," said Sarah Cousineau, group leader in ORNL's Research Accelerator Division and UT joint faculty professor. "Part of that is related to being able to fully characterize or measure a beam in 6D space--and that's something that, until now, has never been done."

Six-dimensional space is like 3D space but includes three additional coordinates on the x, y, and z axes to track motion or velocity.

"Right away we saw the beam has this complex structure in 6D space that you can't see below 5D--layers and layers of complexities that can't be detangled," Cousineau said. "The measurement also revealed the beam structure is directly related to the beam's intensity, which gets more complex as the intensity increases."

Previous attempts to fully characterize an accelerator beam fell victim to "the curse of dimensionality," in which measurements in low dimensions become exponentially more difficult in higher dimensions. Scientists have tried to circumvent the issue by adding three 2D measurements together to create a quasi-6D representation. The UT-ORNL team notes that approach is incomplete as a measurement of the beam's initial conditions entering the accelerator, which determine beam behavior farther down the linac.

As part of efforts to boost the power output of SNS, ORNL physicists used the beam test facility to commission the new radio frequency quadrupole, the first accelerating element located at the linac's front-end assembly. With the infrastructure already in place, a research grant from the National Science Foundation to the University of Tennessee enabled outfitting the beam test facility with the state-of-the-art 6D measurement capability. Conducting 6D measurements in an accelerator has been limited by the need for multiple days of beam time, which can be a challenge for production accelerators.

"Because we have a replica of the linac's front-end assembly at the beam test facility, we don't have to worry about interrupting users' experiment cycles at SNS. That provides us with unfettered access to perform these time-consuming measurements, which is something we wouldn't have at other facilities," said lead author Brandon Cathey, a UT graduate student.

"This result shows the value of combining the freedom and ingenuity of NSF-funded academic research with facilities available through the broad national laboratory complex," said Vyacheslav Lukin, the NSF program officer who oversees the grant to the University of Tennessee. "There is no better way to introduce a new scientist--a graduate student--to the modern scientific enterprise than by allowing them to lead a first-of-a-kind research project at a facility that uniquely can dissect the particles that underpin what we know and understand about matter and energy."

The researchers' ultimate goal is to model the entire beam, including mitigating so-called beam halo, or beam loss--when particles travel to the outer extremes of the beam and are lost. The more immediate challenge, they say, will be finding software tools capable of analyzing the roughly 5 million data points the 6D measurement generated during the 35-hour period.

"When we proposed making a 6D measurement 15 years ago, the problems associated with the curse of dimensionality seemed insurmountable," said ORNL physicist and coauthor Alexander Aleksandrov. "Now that we've succeeded, we're sure we can improve the system to make faster, higher resolution measurements, adding an almost ubiquitous technique to the arsenal of accelerator physicists everywhere."

The PRL paper is titled "First Six Dimensional Phase Space Measurement of an Accelerator Beam." The paper's coauthors also include ORNL's Alexander Zhukov.

"This research is vital to our understanding if we're going to build accelerators capable of reaching hundreds of megawatts," Cousineau said. "We'll be studying this for the next decade, and SNS is better positioned to do this than any other facility in the world."
The Spallation Neutron Source is a DOE Office of Science User Facility. This research was supported by NSF Accelerator Science.

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2018, its budget is $7.8 billion. NSF funds reach all 50 states through grants to nearly 2,000 colleges, universities and other institutions. Each year, NSF receives more than 50,000 competitive proposals for funding and makes about 12,000 new funding awards.

UT-Battelle manages ORNL for DOE's Office of Science. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information about ORNL and its neutron research capabilities, please visit

DOE/Oak Ridge National Laboratory

Related Physics Articles:

Diamonds coupled using quantum physics
Researchers at TU Wien have succeeded in coupling the specific defects in two such diamonds with one another.
The physics of wealth inequality
A Duke engineering professor has proposed an explanation for why the income disparity in America between the rich and poor continues to grow.
Physics can predict wealth inequality
The 2016 election year highlighted the growing problem of wealth inequality and finding ways to help the people who are falling behind.
Physics: Toward a practical nuclear pendulum
Researchers from Ludwig-Maximilians-Universitaet (LMU) Munich have, for the first time, measured the lifetime of an excited state in the nucleus of an unstable element.
Flowers use physics to attract pollinators
A new review indicates that flowers may be able to manipulate the laws of physics, by playing with light, using mechanical tricks, and harnessing electrostatic forces to attract pollinators.
Physics, photosynthesis and solar cells
A University of California, Riverside assistant professor has combined photosynthesis and physics to make a key discovery that could help make solar cells more efficient.
2-D physics
Physicist Andrea Young receives a 2016 Packard Fellowship to pursue his studies of van der Waals heterostructures.
Cats seem to grasp the laws of physics
Cats understand the principle of cause and effect as well as some elements of physics.
Plasma physics' giant leap
For the first time, scientists are looking at real data -- not computer models, but direct observation -- about what is happening in the fascinating region where the Earth's magnetic field breaks and then joins with the interplanetary magnetic field.
Nuclear physics' interdisciplinary progress
The theoretical view of the structure of the atom nucleus is not carved in stone.

Related Physics Reading:

Basic Physics: A Self-Teaching Guide
by Karl F. Kuhn (Editor)

Seven Brief Lessons on Physics
by Carlo Rovelli (Author)

Fundamentals of Physics: Mechanics, Relativity, and Thermodynamics (The Open Yale Courses Series)
by R. Shankar (Author)

Physics Equations & Answers (Quick Study Academic)
by Mark Jackson (Author)

Physics: Principles with Applications (7th Edition) - Standalone book
by Douglas C. Giancoli (Author)

The Cartoon Guide to Physics (Cartoon Guide Series)
by Larry Gonick (Author)

No bullshit guide to math and physics
by Ivan Savov (Author)

Physics (5th Edition)
by James S. Walker (Author)

by David Young (Author), Shane Stadler (Author)

The Elegant Universe: Superstrings, Hidden Dimensions, and the Quest for the Ultimate Theory
by Brian Greene (Author)

Best Science Podcasts 2018

We have hand picked the best science podcasts for 2018. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

The Story Behind The Numbers
Is life today better than ever before? Does the data bear that out? This hour, TED speakers explore the stories we tell with numbers — and whether those stories portray the full picture. Guests include psychologist Steven Pinker, economists Tyler Cowen and Michael Green, journalist Hanna Rosin, and environmental activist Paul Gilding.
Now Playing: Science for the People

#487 Knitting in PEARL
This week we're discussing math and things made from yarn. We welcome mathematician Daina Taimina to the show to discuss her book "Crocheting Adventures with Hyperbolic Planes: Tactile Mathematics, Art and Craft for all to Explore", and how making geometric models that people can play with helps teach math. And we speak with research scientist Janelle Shane about her hobby of training neural networks to do things like name colours, come up with Halloween costume ideas, and generate knitting patterns: often with hilarious results. Related links: Crocheting the Hyperbolic Plane by Daina Taimina and David Henderson Daina's Hyperbolic Crochet blog...