THE RECENT IMPROVEMENT AND VERIFICATION OF DARWIN: DEVELOPMENT OF A NEW DAQ SYSTEM AND RESULTS OF FLIGHT EXPERIMENT

摘要

To improve radiation safety in high-energy accelerator facilities, the authors have been developing the new radiation dose monitor device DARWIN: Dose monitoring system Applicable to various Radiations with WIde energy raNges. DARWIN is composed of (a) a phoswitch-type scintillation detector, which consists of liquid organic scintillator BC501A coupled with ZnS(Ag) scintillation sheets doped with ~6Li, and (b) a data acquisition (DAQ) system for digital analysis of the waveform of the scintillator signals. The DAQ system was recently updated in order to apply DARWIN in monitoring dose rates in radiation fields having time structure,rnintroducing an originally developed module based on a field-programmable gate array. To examine the performance of DARWIN placed in radiation fields composed of varieties of particles over wide energy ranges, the authors mounted DARWIN on a jet aircraft and measured neutron, photon, muon, electron, and positron dose rates at high altitudes. The measured dose rates excellently agreed with the corresponding data calculated by EXPACS over a wide altitude range. This agreement indicates the applicability of DARWIN to dose monitoring in complex radiation fields such as those in high-energy accelerator facilities and aircrafts.