Synthesis of Short-Lived Radioactive Compound H₂¹⁵O Utilizing Activation of Gas Target by A Laser-Driven Deuteron Beam

Abstract

Radioactive water was obtained using a laser-driven deuteron beam. A Ti:sapphire tabletop laser was used to generate optical pulses with a peak power of 36 TW, a pulse duration of 30 fs, and a repetition frequency of 10 Hz. The pulses were focused on a tape target to accelerate deuterons via laser-plasma interaction. The deuterons were incident on nitrogen gas held in a gas chamber. Short-lived positron emitters of ¹⁵O were created via a nuclear reaction of ¹⁴N (d, n)¹⁵O in the chamber and were carried to a synthetic instrument. After laser irradiation for 180 s, we confi rmed activity of 1.2 ± 0.5 Bq in the form of water molecules included in the liquid. To obtain radioactive water, we developed two main experimental techniques: automatic adjustment of laser focusing in a vacuum environment; and image evaluation of the spatial distribution of a deuteron beam.