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May 18, 2015

Beryllium metal target for small neutron sources

RIKEN No.: 08004


Yutaka Yamagata, Katsuya Hirota (Advanced Manufacturing Metrology Laboratory),
Jung-Myoung Ju (Ultra High Precision Fabrication Team)


In recent years, there have been attempts to develop small neutron sources in order to explore the use of neutron beams for scientific and industrial applications. The technology presented here generates neutrons with a small particle beam accelerator, making possible the efficient use of neutrons in combination with neutron optical elements. Several elemental technologies are necessary for the development of small neutron sources. The development of a neutron target to generate the neutrons is one of the most important of these technologies.


The low-energy proton beams and deuteron beams used in small neutron sources destroy the metallic plate as a result of hydrogen embrittlement when they stop within the beryllium layer. The inventers therefore precisely calculated the penetration range of charged particles inside the target and adjusted the thickness of the beryllium layer so that the proton beam would stop downstream of it. In addition, they solved the problems of heat removal and hydrogen embrittlement simultaneously and also successfully improved the safety during maintenance with low activation by selecting a metal that had high hydrogen diffusibility, good thermal conductivity, and a relatively low long-term activation from neutron irradiation to be the backing plate.

Figure showing the process of neutron generation

Fig.1: Schematic diagram of neutron generation target

Figure of beryllium target

Fig.2: Manufactured beryllium target


  • Extended life of neutron generation target
  • Simplified maintenance thanks to low long-term activation
  • Reduction in running cost thanks to extended life


  • Neutron generation target for small neutron sources


  • 1.Japanese patent No.5888760