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[SCI 2008] Performance of a high-pressure xenon ionization

관리자 2011.03.31
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Performance of a high-pressure xenon ionization chamber
for environmental radiation monitoring
 
H.S. Kim , S.H. Park, J.H. Ha , Y.K. Kim , J.K. Kim, S.Y. Cho
 
  High-pressure xenon (HPXe) ionization chambers are ideal for use in uncontrolled environments, as a detector's response has been shown to be uniform over large temperature ranges (20-170℃). A cylindrical HPXe ionization chamber, which was configured with a shielding mesh to improve its energy resolution, was designed on the basis of an EGSnrc simulation code to extract an optimal density of Xe gas and a thickness of the chamber's wall. A Garfield, which was coupled with a Maxwell electric field calculator, was also employed for the electron drift simulations due to the geometry of the adapted shielding mesh. Shielding inefficiency was also calculated. A spherical ionization chamber was also designed to monitor an environmental radiation level and the responses with the fabricated HPXe ionization chamber were compared. A noble gas system was constructed to create a noble gas with a high purity and to inject the noble gas at up to 60atm. The combination of an oxisorb, a molecular sieve, and a high-temperature getter can minimize the electro-negative impurities, such as the O2 and N2 gas, to below about several ppb levels. Preliminary tests such as leakage currents, saturation currents, and gas leak tests were performed. The performance of the two fabricated ionization chambers at a low dose rate was tested by using a conventional shadow technique with a NIST certified 0.906mCi 226Ra standard source in a calibration room at KAERI.
 
Keywords : Ionization chamber; Environmental radiation; Shadow shielding technique; EGSnrc
[SCI 2008] Operational Characteristics of Ionization Chambers
[SCI 2008] Development of a high pressure Xe Ionization chamber