High-energy radiation monitoring based on radio-fluorogenic co-polymerization. I: Small volume in situ probe.
A method of radiation dosimetry is described which is based on the radiation-induced initiation of polymerization of a bulk monomer (e.g. methyl methacrylate) containing a small concentration (about 100 ppm) of a compound which is non-fluorescent but which becomes highly fluorescent when it is incorporated into a growing polymer chain of the bulk monomer. We call the overall process 'radio-fluorogenic co-polymerization' or RFCP for short. The method is illustrated by results on the in situ monitoring of the accumulated dose within the irradiation chamber of a cobalt-60 gamma-ray source using a small plastic capsule containing about 0.2 ml of an RFCP solution. Remote monitoring of the fluorescence is carried out on a timescale of seconds using optical fibres connecting the probe to a 360 nm LED excitation source and a miniature spectrophotometer. The fluorescence is permanent and the intensity is linearly proportional to the accumulated dose from a few tenths of a gray up to hundreds of gray. The sensitivity to dose depends on the polymerizable monomer used and obeys a square root dependence on dose rate over the range studied, 0.27-3.76 Gy min(-1). The polymeric nature of the fluorescent product suggests that the RFCP effect could be used to provide fixed two- or three-dimensional fluorescent images of dose deposition in gel films or phantoms.
Reactor Institute R3/RIH, Technical University of Delft, Mekelweg 15, 2629 JB Delft, The Netherlands. J.M.Warman@TUDelft.NL
J M
JM
Warman
M P
MP
de Haas
L H
LH
Luthjens
D017076:Computer-Aided Design; D004867:Equipment Design; D019544:Equipment Failure Analysis; D011108:Polymers / Q000737:chemistry* / Q000528:radiation effects*; D011829:Radiation Dosage; D011834:Radiation Monitoring / Q000295:instrumentation* / Q000379:methods*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013050:Spectrometry, Fluorescence / Q000295:instrumentation* / Q000379:methods*
D011108:Polymers