Online ISSN: 1884-4111 Print ISSN: 0033-8303
Radioisotopes 66(11): 587-593 (2017)

特集Special Issues

24 放射線化学と陽電子消滅24 Radiation Chemistry and Positron Annihilation

日本原子力研究開発機構原子力基礎工学研究センターNuclear Science and Engineering Center, Japan Atomic Energy Agency (JAEA) ◇ 319–1195 茨城県那珂郡東海村大字白方2–4 ◇ 2–4 Shirakata, Tokai-mura, Naka-gun, Ibaraki Pref. 319–1195, Japan

発行日:2017年11月15日Published: November 15, 2017


A positron is an antiparticle of an electron. A positron injected into solids or liquids annihilates with one of the electrons. The mean lifetime of positron annihilation in the materials is from about 100 picoseconds to several nanoseconds. The mass energy of the electron and the positron is emitted as two γ-rays in most cases. The energy of the annihilation γ-ray can provide the information on the state of the electron and the positron just before the annihilation. Positronium (Ps; a bound state of an electron and a positron) formation time is usually about one picosecond and can probe reactions occurred up to picosecond. Furthermore, it is also possible to discuss the reactions of spur species occurred at nanosecond time region by reactions of long-lived triplet Ps. Here, the methods and the studies related to radiation chemistry are introduced to start new challenges by the positron annihilation methods for radiation chemistry researches.

Key words: positron; positronium; positron annihilation; radiation chemistry; spur

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