Res. Chem. Intermed.
, Vol. 27, No. 4,5, pp. 333–341 (2001)
Ion beam pulse radiolysis study on intra-track reactions
in aqueous solutions
Nuclear Engineering Research Laboratory, School of Engineering, The University of Tokyo,
2-22 Shirakata Shirane, Tokai-mura, Ibaraki, 319-1188, Japan
Abstract—A pulse radiolysis system using proton and He
beams with pulse duration of longer
than 1 ¹s has been constructed at the HIMAC facility and used in radiation chemical studies. Radical
yields decrease with an increase in LET, and scavenger systems to be used as probes must be examined
carefully for the possibility of secondary reactions. The reliabilityof the dose evaluation in the present
experiment was con rmed by the comparison of the results between steady state and pulse irradiation
experiments. In addition, the aqueous methyl viologen solution containing formate was proposed as a
promising chemical dosimeter in pulse and steady state irradiation with ion beams.
The radiation chemistry of aqueous solutions induced by low linear energy transfer,
LET, radiation such as X- and
-rays and fast electrons has been studied for more
than ve decades. There is a considerable amount of accumulated knowledge for
these types of radiation. On the contrary, our understanding of the reactions induced
by high LET radiation, which is closely related to the radiation effects in mixed
elds, is far from complete and clari cation of the intra-track reactions is urgently
required. In the present paper, a pulse radiolysis technique using pulsed proton and
helium beams has been employed to examine the characteristics of the reactions
induced by high LET radiation in aqueous solutions. First, the characteristics of
the system are brie y explained and the scavenging method is introduced. The
experimental results in several aqueous solutions are then presented and discussed.
In addition, a promising aqueous dosimeter applicable to both pulse and steady state
irradiation is proposed.