Fission-fragment registration and etching properties of diallyl phthalate with reference to its use as an external detector in fission-track dating

The properties of diallyl phthalate (DAP) resin were studied with reference to its use as an external detector in fission-track (FT) dating. The etching characteristics and bulk etch rates of DAP in 30% KOH in water at 90 deg. C (PW-etch) and 15% KOH, 65% ethanol and 20% H2O at 60 deg. C (PEW-etch) are different. In the case of the PW-etch, high background densities of recoil tracks were observed, that are produced by collisions of fast neutrons with C and O in the detector during irradiation. The PEW-etch does not reveal the background tracks as a result of the high bulk etch rate. The PEW-etch is recommended for use in FT dating because of the absence of a recoil-track background and the shorter etching time. The optimum etching time for both solutions was determined in step-etching experiments. For both etching solutions, the track density in DAP is 4-5% higher than in muscovite mica, as a result of the lower track registration threshold. Automated track counts confirm that image analysis enables accurate determinations of the track density in DAP etched in the PEW-etch