Study on The Quantification of Cosmic-Ray Component Contributed to Natural Background Radiation Exposure

자연 방사선량 중 우주선 기여 성분 정량 연구

  • Jun, Jae-Shik (Department of Physics, Chungnam National University) ;
  • Oh, Hi-Peel (Department of Physics, Chungnam National University) ;
  • Ha, Chung-Woo (Korea Advanced Energy Research Institute) ;
  • Oh, Heon-Jin (Department of Physics, Chungnam National University) ;
  • Kang, In-Seon (Department of Physics, Chungnam National University)
  • Published : 1988.12.20

Abstract

In order to quantify the contribution of cosmic-ray ionizing component to the dose given by natural background radiation, a series of measurement has been carried out using LiF TLDs for about one and a half years on quarterly basis. Three different types of LiF TLDs namely, chips and PTFE based disks of $^{7}LiF$, and the same disks of $^{6}LiF$ for identifying possible contribution of neutron component were used. Measurements were made by placing badge-incased TLDs in a lead castle of 10 to 15cm thick installed in a room on the third floor of a four-story building in CNU Daedeok campus for 5 cycles of 90 days. For comparison a series of spectrometric study was also performed for the energy region over 3MeV using a 3'${\phi}\;{\times}\;3$'NaI(Tl) scintillation detector in association with an MCA of 1024 channels, and it was found that the data obtained by the TLDs placed in the lead castle indicate 75% of the dose given by outdoor cosmic-ray component. The results obtained by the TLDs through correction for shielding loss show that the outdoor dose contribution of ionizing component of cosmic rays at this campus is $34.3{\pm}1.1nGy/h$ which satisfactorily agrees with that expected for our particular location of measurement.

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