News releases

JAEA succeeded in developing a bright positron beam to be used for microscopic analysis of surface nano-materials

Aug. 7, 2006

The Japan Atomic Energy Agency (JAEA) succeeded in developing a positron beam with the brightness of one order of magnitude greater as compared to the previous experiments. Using the bright positron beam, it has been possible to determine the atomic arrangements of surface super-structures precisely. In the future, the contribution to nano-technology is anticipated. The above research result is obtained by the ‘Research Group for Dynamics of Surface Super-Structures using Advanced Positron Beam TechniquesEof the Advanced Science Research Center.
Nano-materials fabricated on solid surfaces are expected to be used as advanced functional materials, for instance as the quantum dots and quantum wells in the semiconductor industry. To understand properties of such surface nano-materials, it is needed to know their atomic arrangements. Development of the techniques to determine the atomic arrangements of surface nano-structures is therefore primarily important. For this purpose, JAEA has been developing a bright positron beam. Positron, which is the anti-particle of the electron, has a tendency to be repelled from materials. Therefore, the penetration depth is very limited and the total reflection occurs in an appropriate condition. Using the total reflection of a positron beam, it turns out to be possible to determine the atomic arrangement of surface nano-structures more precisely as compared to existing methods. Recently, JAEA improved the positron source and adopted electromagnetic lenses similar to those used in the electron microscope. Consequently, JAEA succeeded in enhancing the brightness of positron beams by one order of magnitude as compared to the past. Furthermore, as a result of probing a silver ultra-thin film on a silicon surface (0.2 nm thick), of which the atomic arrangement is still unknown, using the bright positron beam, JAEA succeeded to clarify the atomic arrangement.
In the future, the bright positron beam will be used extensively in the research field including surface nano-materials. The above result has been published in Surface Science (Surf. Sci. 600(2006)3141-3146).





online information

Location of environment monitoring posts measuring amount of radiation. (details)

links

International link directory of related websites.