Laser-driven neutron generation with single-view resonance spectroscopy

Scientists at the Institute of Laser Engineering at Osaka University determined a method and an efficient way to generate neutrons from a laser-driven source and used it to perform neutron resonance analysis by faster than conventional methods. This work could help bring non-invasive testing to many manufacturing and pharmaceutical applications.

Although many microscopes use photons or even electrons to study small samples, scientists have also used neutrons in many experiments, such as neutron scattering, to study samples made as well as biological samples. As neutral particles, neutrons are suitable for non-destructive investigations of the magnetic and atomic properties of substances under consideration, as they are not affected by electric charge. New methods exist for producing neutrons in large quantities, such as using laser-driven neutron sources, but the underlying mechanism remains unclear.

Now, a group of researchers led by the University of Osaka have created a laser-driven neutron source and determined a new scaling law between the laser power and the number of neutrons produced. They found that increasing the energy provided neutrons equal to the fourth power, which can lead to very large changes based on relatively small amounts of additional energy.

Using this rule, a test called neutron resonance absorption was performed to determine the components of the test sample. “Neutron sources can be used in applications ranging from radiography, spectroscopy, defense, to medicine,” says first author Akifumi Yogo.

In the experiment, the researchers directed a very powerful laser beam through a foil of deuterated polystyrene. The ejected ions collided with a block of beryllium, which produced more neutrons. A small detector device was used to slow down the neutrons to travel at the correct speed through the sample.

Based on the rate of neutron absorption, the atoms in the sample can be identified. “We succeeded in reducing the measurement time from several hours to a fraction of a second, which enables one-shot experiments involving fast events,” says senior author Ryosuke Kodama.

Processes that take place in seconds or minutes can now be observed in real time, something that was not possible using the old methods with low neutron energy. The results of this research can lead to a significant increase in the speed of industrial quality control or biological sample identification.