Tracking hydrogen movement using subatomic particles

September 26, 2018, Osaka University
Tracking hydrogen movement using subatomic particles
Figure: When a negative muon (μ-) is implanted into MgH2, the μ- is trapped by the muon atomic orbitals near a Mg nucleus. Since μ- has a polarized spin, we can obtain information about the magnetic field at the Mg nucleus sites, formed by the hydrogen nucleuses, through the observation of how the μ- spin depolarizes with time. Credit: J. Sugiyama/Toyota Central Research and Development Laboratories Inc.

A muon is an unstable subatomic particle similar to an electron but with much greater mass. The lifetime of a muon is only a couple of microseconds, but this is long compared with the lifetimes of many unstable subatomic particles. Because of their comparatively long lifetime, positive muons are often used to detect internal magnetic fields in solid materials. However, negative muons have seldom been used for this purpose because a large data set is required to obtain reliable results and experimental data collection times are normally limited. Recently, researchers developed a system that can count muon events at a much faster rate, allowing an experiment to be completed in a suitable time frame. Using this system, a Japanese collaboration has realized the long-standing goal of using negative muons to observe the local nuclear magnetic fields in a solid for the first time.

As explained in their article in Physical Review Letters, the team used as the solid in their experiments. Magnesium hydride has a formula of MgH2 and is a potential candidate as a hydrogen storage material. Magnesium hydride was selected for study in experiments using the negative beam because muons initially captured on hydrogen are transferred quickly to magnesium, which allowed the transfer process of hydrogen to be investigated.

"The magnesium atoms exposed to the negative muon beam were effectively converted to sodium," says first author Jun Sugiyama at Toyota Central Research & Development Laboratories Inc. "The local of the hydrogen atoms around these converted atoms was then able to be detected, which meant that we could track hydrogen diffusion."

The experiments used a high-intensity muon beam and highly integrated positron detector system to detect the local magnetic fields in the magnesium hydride sample. The obtained spectra were consistent with the magnesium atoms having a random magnetic field, agreeing with theoretical predictions. In particular, the results agreed with estimations from dipole field calculations, indicating that the nuclear magnetic fields of hydrogens in hydride were indeed observed.

"Our approach using negative muons to detect the local behavior of ions is attractive because it allows us to study the dynamics of light elements in a solid from the fixed point of the nucleus," says co-author Kazuhiko Ninomiya at Osaka University. "This approach is therefore complementary to nuclear magnetic resonance spectroscopy."

Using this negative muon-based technique, it is now possible to track the movement of in a solid, which should aid the development of .

Explore further: Scientists introduce new material to store hydrogen

More information: Jun Sugiyama et al. Nuclear Magnetic Field in Solids Detected with Negative-Muon Spin Rotation and Relaxation, Physical Review Letters (2018). DOI: 10.1103/PhysRevLett.121.087202

Related Stories

Scientists introduce new material to store hydrogen

September 6, 2017

Scientists of Siberian Federal University and the Institute of Physics of the SB RAS produced a new material for hydrogen storage. The material is based on magnesium hydride, and can store hydrogen mass of about 7 percent ...

On the way to hydrogen storage?

April 19, 2011

(PhysOrg.com) -- The car of the future could be propelled by a fuel cell powered with hydrogen. But what will the fuel tank look like? Hydrogen gas is not only explosive but also very space-consuming. Storage in the form ...

Recipe for muon pair creation, in theory

January 19, 2016

A true-muonium only lives for two microseconds. These atoms are made up one positively and one negatively charged elementary particle, also known as muons. Although they have yet to be observed experimentally, a Japanese ...

Muons help understand mechanism behind hydrogen storage

November 18, 2014

It is ever more necessary to find alternative ways to store energy. Energy storage is required when energy is supplied intermittently, as for instance for wind power, or for mobile applications like cars. Hydrogen is a promising ...

New Alzheimer's research method uses muons

September 6, 2017

Alzheimer's disease is the most common form of dementia. This makes fundamental research on the precise cause of the illness of vital importance. One of the possible suspects is a certain protein filled with iron. Leiden ...

Muon machine makes milestone magnetic map

January 29, 2018

Muons are mysterious, and scientists are diving deep into the particle to get a handle on a property that might render it—and the universe—a little less mysterious.

Recommended for you

Physicists reveal why matter dominates universe

March 21, 2019

Physicists in the College of Arts and Sciences at Syracuse University have confirmed that matter and antimatter decay differently for elementary particles containing charmed quarks.

ATLAS experiment observes light scattering off light

March 20, 2019

Light-by-light scattering is a very rare phenomenon in which two photons interact, producing another pair of photons. This process was among the earliest predictions of quantum electrodynamics (QED), the quantum theory of ...

How heavy elements come about in the universe

March 19, 2019

Heavy elements are produced during stellar explosion or on the surfaces of neutron stars through the capture of hydrogen nuclei (protons). This occurs at extremely high temperatures, but at relatively low energies. An international ...

Trembling aspen leaves could save future Mars rovers

March 18, 2019

Researchers at the University of Warwick have been inspired by the unique movement of trembling aspen leaves, to devise an energy harvesting mechanism that could power weather sensors in hostile environments and could even ...

0 comments

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.