Nav: Home

Neutrons measured with unprecedented precision using a 'magneto-gravitational trap'

May 15, 2018

BLOOMINGTON, Ind. -- A study led in part by physicists at the Indiana University Center for the Exploration of Energy and Matter could provide new insight into the composition of the universe immediately after the Big Bang -- as well as improve calculations used to predict the life span of stars and describe the rules that govern the subatomic world.

The study, published May 11 in the journal Science, reports a highly accurate way to measure the decay rate of neutrons. An author on the study, Chen-Yu Liu, is a professor in the IU Bloomington College of Arts and Sciences' Department of Physics.

"This is a significant improvement compared to previous experiments," said Liu, who is a leader on the UNCtau experiment, which uses neutrons from the Los Alamos Neutron Science Center Ultracold Neutron source at Los Alamos National Laboratory in New Mexico. "The data is far more accurate than what we've had before."

The rate of the decay of neutrons -- subatomic particles with no charge -- is significant because it is used to predict the proportion of hydrogen and helium in the universe a few minutes after the Big Bang. The number also affects calculations used to determine how quickly hydrogen atoms burn up inside stars and the rules that control the elementary particles like quarks and gluons. This is because during neutron decay, one "up" quark transforms into a "down" quark, a process that physicists don't yet fully understand.

Scientists currently use two methods to isolate neutrons and calculate their decay rates:
  • The "bottle" method: Counting the number of neutrons that remain over time after being trapped inside a container.
  • The "beam" method: Measuring the rate of protons that emerge from a neutron beam generated by a nuclear reactor.

Some physicists regard the beam method as more accurate because the bottle method risks miscounting neutrons absorbed into the container as disappearing from decay. But the study from Liu and colleagues uses an invisible container made from magnetic fields and gravity to eliminate the risk of interference from physical material. As a result, the experiment can measure a neutron's lifetime with a high level of precision.

"A neutron could technically live inside our trap for three weeks, which is much longer than any other previously constructed 'bottle' traps," Liu said. "This long trap lifetime is what makes it possible to achieve a highly accurate measurement."

The use of a "magneto-gravitational trap," in which the neutrons' magnetic charge and mass prevent them from escaping their container, also makes it easier to measure the neutrons because the bottle is "lidless," Liu said.

Liu's lab joined the UNCtau experiment in 2011 to help re-invigorate the project. The work required five years to design, fabricate, test and install their equipment at the neutron source in Los Alamos, after which the team began to run experiments and collect data. Members of Liu's lab regularly travel to New Mexico to test equipment, run experiments and record the results.

"Five years to get an experiment running and producing data is very fast in our field," Liu said. "We spent about six months on site and six months creating hardware each year. It was really a cycle of fast prototyping and improvement. We would never have been able to renovate the technology without the mechanical and technical support available at the IU Center for the Exploration of Energy and Matter."
-end-
Other IU authors on the paper are Ph.D. students Nathan Callahan, Evan Adamek and Daniel J. Salvat; mechanical engineer Walt Fox; and technician John Vanderwerp. Other IU contributors were Gerard Visser, electrical engineer; Frank Gonzalez, a graduate student; and Chris Cude, an undergraduate at the time of the study.

Additional authors come from Los Alamos National Laboratory, North Carolina State University, Oak Ridge National Laboratory, Virginia Polytechnic Institute, West Point Military Academy, the California Institute of Technology, Tennessee Technical University, DePauw University, the University of Washington, the Institut Laue-Langevin in France and the Joint Institute for Nuclear Research in Russia. The study was supported in part by the National Science Foundation, the Department of Energy and the IU Center for Spacetime Symmetries.

Indiana University

Related Big Bang Articles:

'Big Food' companies have less power than you might think
A Dartmouth study finds that 'Big Food' companies are striving to make food more sustainable from farm to factory but have less power than you might think.
Looking for signs of the Big Bang in the desert
The Simons Observatory will be built in the Chilean Atacama desert for the purposes of studying primordial gravitational waves which originated in the first instants of the Big Bang.
More bang for the buck
Researchers find cost-effective solutions to sediment runoff and other land-based pollution affecting West Maui reefs
Big data for the universe
Astronomers at Lomonosov Moscow State University in cooperation with their French colleagues and with the help of citizen scientists have released 'The Reference Catalog of galaxy SEDs,' which contains value-added information about 800,000 galaxies.
Can big data yield big ideas? Blend novel and familiar, new study finds
Struggling to get your creative juices flowing for a new idea or project?
Why big brains are rare
Do big-brained creatures steal energy for them from other organs or eat more to supply this expensive tissue?
New antimatter breakthrough to help illuminate mysteries of the Big Bang
Swansea University physicists working with an international collaborative team at CERN, conduct the first precision study of antihydrogen, the antimatter equivalent of hydrogen.
Big data for little creatures
A multi-disciplinary team of researchers at UC Riverside has received $3 million from the National Science Foundation Research Traineeship program to prepare the next generation of scientists and engineers who will learn how to exploit the power of big data to understand insects.
How we escaped from the Big Bang
A Griffith University physicist is challenging the conventional view of space and time to show how the world advances through time.
Big PanDA tackles big data for physics and other future extreme scale scientific applications
A team of physicists just received $2.1 million in funding for 2016-2017 from DOE's Advanced Scientific Computing Research program to enhance a 'workload management system' for handling the ever-increasing data demands of two experiments at the Large Hadron Collider and expanding its use as a general workload management service for a Department of Energy supercomputer.

Related Big Bang Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Climate Crisis
There's no greater threat to humanity than climate change. What can we do to stop the worst consequences? This hour, TED speakers explore how we can save our planet and whether we can do it in time. Guests include climate activist Greta Thunberg, chemical engineer Jennifer Wilcox, research scientist Sean Davis, food innovator Bruce Friedrich, and psychologist Per Espen Stoknes.
Now Playing: Science for the People

#527 Honey I CRISPR'd the Kids
This week we're coming to you from Awesome Con in Washington, D.C. There, host Bethany Brookshire led a panel of three amazing guests to talk about the promise and perils of CRISPR, and what happens now that CRISPR babies have (maybe?) been born. Featuring science writer Tina Saey, molecular biologist Anne Simon, and bioethicist Alan Regenberg. A Nobel Prize winner argues banning CRISPR babies won’t work Geneticists push for a 5-year global ban on gene-edited babies A CRISPR spin-off causes unintended typos in DNA News of the first gene-edited babies ignited a firestorm The researcher who created CRISPR twins defends...