Design of a Badge Filter System for Measurement of Hp(10) with the New Type of TL Dosimeter $CaSO_4:Dy,P$

신형 TL 선량계인 $CaSO_4:Dy,P$를 이용한 Hp(10) 측정용 배지의 필터체계 설계

  • Kim, H.K. (Dept. of Nuclear Engineering, Hanyang University) ;
  • Kwon, J.W. (Dept. of Nuclear Engineering, Hanyang University) ;
  • Lee, J.K. (Dept. of Nuclear Engineering, Hanyang University) ;
  • Kim, J.L. (Korea Atomic Energy Research Institute(KAERI))
  • Published : 2003.06.30

Abstract

This study was intended to estimate Hp(10) recommended by the ICRU using the $CaSO_4:Dy,P$ element developed in the KAERI. For the estimation of Hp(10), TL response should be compensated properly through the energy range using filter materials since $CaSO_4:Dy,P$ is of severe photon energy dependent response. Various experiments and computations using Monte Carlo Code were carried out for designing filter satisfying the performance requirements of the ISO related to TL dosimeter. Under the completed filter, the relative response of $CaSO_4:Dy,P$ showed $0.75{\sim}1.0$ for photons in the range of $20{\sim}662keV$. Especially it was possible to reduce the thickness of front filter and simplify the filter combination with rear filter of larger diameter and to considerably improve angular dependence by introducing taper to the filler.

한국원자력연구소에서 개발한 $CaSO_4:Dy,P$를 이용하여 ICRU에서 권고하는 Hp(10)을 평가하고자 하였다. $CaSO_4:Dy,P$는 광자에 내하여 높은 에너지 의존성을 지니므로 Hp(10) 평가를 위해서는 필터물질을 이용하여 모든 에너지에 대하여 반응도를 적절히 보상하여야 한다. ISO에서 권고하는 열형광선량계의 성능요건을 만족하는 필터설계를 위해 몬테칼로 코드를 이용한 이론적 계산과 검증 실험을 수행하였다. 완성된 필터 하에서 $CaSO_4:Dy,P$ 소자는 $20{\sim}662keV$에 이르는 광자 에너지 범위에서 $0.75{\sim}1.0$의 상대반응도를 보였다. 특히 직경이 큰 후방필터를 설계함으로써 전방필터의 두께를 감소하고 필터 조합을 단순화하였으며 테이퍼를 도입하여 선량계의 방향의존성을 대폭 개선할 수 있었다.

Keywords

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