Playing billiards with a laser beam

January 31, 2018, Ludwig Maximilian University of Munich
Playing billiards with a laser beam
Artist’s impression of the laser-plasma interaction: The laser beam approaches the electrodynamic particle trap from the left and impinges on the levitated plastic microsphere, accelerating a bunch of electrons and protons. Credit: Marcel Menke

A research team led by physicists at LMU Munich reports a significant advance in laser-driven particle acceleration. Using tiny plastic beads as targets, they have produced proton bunches that possess unique features, opening up new opportunities for future studies.

In their experiments, a team led by at LMU Munich fired a powerful laser pulse at a micrometer-sized plastic sphere, blasting a bunch of protons from the target and accelerating them to velocities approaching the speed of light. The resulting velocity distribution is much narrower than that obtained when thin metal foils are used as targets. The physicist now present their research results in the scientific journal Nature Communications

Recent years have seen remarkable advances in the development of a new approach to the acceleration of . This strategy makes use of the intense electric fields associated with pulsed, high-energy laser beams to accelerate electrons and protons to 'relativistic' velocities (i.e. speeds approaching that of light). Hitherto, the laser shot has generally been directed at a thin metal foil, generating and accelerating a plasma of and positively charged ions. Physicists at LMU have now replaced the foil target by a plastic microsphere with a diameter of one-millionth of a meter. These beads are so tiny that they cannot be stably positioned by mechanical means. Instead, the researchers use an electric field to levitate the target particle. Using a feedback circuit, the levitated bead can be trapped with sufficient precision to ensure that it does not drift off the beam axis. The electromagnetic trap was designed and built in the Department of Medical Physics at LMU.

"The basic approach is analogous to collisions between billiard balls. In our experiment, one of the balls is made of light and the other is our tiny levitated target," explains Peter Hilz, who led the experiments. This novel approach to the generation of beams will make experiments feasible which have hitherto been out of reach.

Explore further: A magnetic brake on proton acceleration

More information: P. Hilz et al. Isolated proton bunch acceleration by a petawatt laser pulse, Nature Communications (2018). DOI: 10.1038/s41467-017-02663-1

Related Stories

A magnetic brake on proton acceleration

January 30, 2018

Shine a powerful laser onto a solid, and you get a beam of high-energy protons. Far from being a curiosity, this phenomenon has important applications, such as in neutron-generation research. Theoretically, the more intense ...

Focused laser power boosts ion acceleration

August 7, 2015

An international team of physicists has used carbon nanotubes to enhance the efficiency of laser-driven particle acceleration. This significant advance brings compact sources of ionizing radiation for medical purposes closer ...

Recommended for you

Gravitational wave detectors to search for dark matter

August 16, 2018

Gravitational wave detectors might be able to detect much more than gravitational waves. According to a new study, they could also potentially detect dark matter, if dark matter is composed of a particular kind of particle ...

Taking a closer look at unevenly charged biomolecules

August 16, 2018

In clinical diagnostics, it is critical to monitor biomolecules in a simple, rapid and sensitive way. Clinicians most often monitor antibodies because these small proteins attach to antigens, or foreign substances, we face ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

Steelwolf
not rated yet Jan 31, 2018
I will put the Number 8 Protron in the Left hand magnetic trap on the break...

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.