Measurement of absolute absorbed dose and dose-equivalent response for instruments used around high-energy proton accelerators

The absolute dose-equivalent response been measured over a broad neutron energy range (from thermal to 280 MeV) for three instruments used routinely for the determination of dose equivalent around the CERN/multi-GeV proton accelerators. While the rem ionization chamber - a modified Anderson and Braun rem counter - falls off considerably in response at higher neutron energies, the behaviour of the REM2 recombination chamber suggests that it can still be used in stray fields around high-energy proton accelerators. A tissue-equivalent ionization chamber tested for its response to absorbed dose shows that its response is governed by absorption and build-up phenomena in its walls. It is possible to get a reasonable estimate of dose equivalent by multiplying its reading with a mean quality factor.