Powering Neutron Science

Osaka University researchers investigated the physics of laser-driven neutron sources, and found the relationship between the power and the neutrons generated. They were able to decrease the exposure time needed for neutron absorption experiments, which may be employed in biomedical research.

Fig. 1
(a) Setup of the Laser-driven Neutron Source (LDNS) and the beamline for the neutron resonance absorption spectroscopy experiment developed by Osaka University. (b) The neutron spectrum showing the elements of the sample (Indium, Tantalum and Silver) located on the neutron beamline. The spectrum was obtained by a single pulse of neutrons lasting just 1/100,000,000 sec.

Researchers at Osaka University studied the effect of power consumption on laser-driven neutron creation, and used it to perform an extremely rapid elemental analysis, which may help in improving the resolution of biological and industrial sample testing

 Osaka, Japan – Scientists from the Institute of Laser Engineering at Osaka University determined the mechanism and functional form for the yield of neutrons from a laser-driven source, and used it to carry out a neutron resonance analysis much faster than conventional methods. This work may help bring non-invasive testing to more applications in manufacturing and medicine.

 While most microscopes use photons or even electrons to study small samples, scientists have also employed neutrons in a wide array of tests, such as in neutron scattering, to study both manufactured samples as well as biological specimens. As neutral particles, neutrons are ideal for non-destructive investigation of the magnetic and atomic properties of objects under consideration, since they are unaffected by electric charge. Newer methods exist for producing neutrons in large numbers, like using laser-driven neutron sources, but the underlying mechanism remains unclear.

 Now, a team of researchers lead by Osaka University developed a laser-driven neutron source and determined a new scaling law between the laser intensity and the number of neutrons produced. They found that increasing the intensity yielded neutrons proportional to the fourth power, which can lead to very large changes based on relatively small investments of additional power. Using this law, an analysis called neutron resonance absorption was performed to identify the elements in the experimental sample. “Neutron sources can be used in applications ranging from radiography, spectroscopy, security, to medicine,” says first author Akifumi Yogo.

 In an experiment, the researchers directed an extremely powerful laser beam at a foil of deuterated polystyrene. The ions that came out collided with a block of beryllium, which in turn created a large flux of neutrons. A small moderator device was used to slow the neutrons so they would be moving the correct speed to pass through the sample. Based on the neutron absorption rate, the atoms in the sample could be determined. “We successfully reduced the measurement time from several hours to a tiny fraction of a second, enabling single-shot experiments involving fast phenomena,” says senior author Ryosuke Kodama.

 Processes that occur over the course of seconds or minutes can now be monitored in real time, which was not possible using older methods with lower neutron intensities. The results of this research can lead to significant increases in speed for industrial quality control or biological sample identification.


The work is published in Physical Review X as “Laser-driven Neutron Generation Realizing Single-Shot Resonance Spectroscopy” DOI: https://journals.aps.org/prx/abstract/10.1103/PhysRevX.13.011011

Fig. 2
The neutron yield per steradoam as a function of the laser intensity,, showing fourth power dependency on the laser intensity

About Osaka University

Osaka University was founded in 1931 as one of the seven imperial universities of Japan and is now one of Japan's leading comprehensive universities with a broad disciplinary spectrum. This strength is coupled with a singular drive for innovation that extends throughout the scientific process, from fundamental research to the creation of applied technology with positive economic impacts. Its commitment to innovation has been recognized in Japan and around the world, being named Japan's most innovative university in 2015 (Reuters 2015 Top 100) and one of the most innovative institutions in the world in 2017 (Innovative Universities and the Nature Index Innovation 2017). Now, Osaka University is leveraging its role as a Designated National University Corporation selected by the Ministry of Education, Culture, Sports, Science and Technology to contribute to innovation for human welfare, sustainable development of society, and social transformation.

Website: https://resou.osaka-u.ac.jp/en

Published: 01 Feb 2023


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Global Strategy Unit

1-1 Yamadaoka, Suita,Osaka 565-0871, Japan

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Japan Society for the Promotion of Science
Ministry of Education, Culture, Sports, Science and Technology