Dr. Masanori Koshimizu, Associate Professor

Dr. Masanori Koshimizu

Development of Scintillation Materials having Nanoscale Structure

Tohoku University Graduate school of Engineering

*The organization and the title are those when awarded

Abstract

  • 日本語
  • English

我々は,ナノメートルスケールの構造を有する材料を用い,新規のシンチレータ材料開発に成功してきた。ナノメートルスケールの構造を有する材料を,シンチレータとして用いることに成功した要因は,下記の2点である。

  1. 半導体からの励起子発光に基づく,高速シンチレータ開発に成功した。これは,半導体ナノ構造での量子閉じ込め効果を利用することにより,室温において,高効率の励起子発光が利用可能となるためである.
  2. プラスチックシンチレータの検出効率を劇的に向上することに成功した。放射線との相互作用機能を担う酸化物ドメインと,発光機能を担うプラスチックシンチレータドメインから構成される,ナノハイブリッド材料開発により,プラスチックシンチレータの高速応答性と,高エネルギーX線や中性子に対して高い感度を持つ材料開発に成功した。

上記のアプローチによるシンチレータ材料開発は,希土類イオンの発光中心を用いる従来のアプローチとは一線を画すものであり,当該分野における新機軸を打ち出すものである。

We have developed novel scintillation materials having a nanoscale structure.Such materials afford two main advantages:

  1. Free exciton luminescence of semiconductor nanostructures can be usedowing to quantum confinement effects.
  2. The detection efficiency of plastic scintillators can be enhanced by fabricating plastic-oxide nanocomposite materials, which can be separated into two parts: a plastic scintillator domain and an oxide domain with which high-energy photons or neutrons interact. Based on the above approach, we have successfully fabricated scintillation materials having self-organized quantum well or quantum dot structure, and we have also fabricated plastic-oxide nanocomposite scintillation materials.

This approach is in direct contrast to the conventional method in which rare-earth ions are used as luminescence centers, and paves the way to synthesize novel high-quality scintillation materials by controlling the higher-order structure of the materials.

Research summary

Scintillators are materials which emit light when being irradiated with ionizing radiation.

Due to their high sensitivity and fast response, they are widely used as radiation detectors in various applications ranging from fundamental scientific research to environmental monitoring.

However, improvement in the response time is highly difficult in the case of conventional approach.

Dr. Koshimizu developed novel scintillation materials having a nanoscale structure.

One such example is semiconductor nanostructures which emit free exciton luminescence.

His approach can pave the way to synthesize high-quality scintillation materials by controlling the high-order structure, and open up a possibility in fabricating next-generation scintillation materials with fast response.

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