범용 실리콘 방사선 센서를 이용한 우주방사선 선량계 개발

천종규,김성환 한국방사선학회 2023 한국방사선학회 논문지 Vol.17 No.3

Aircrews and passengers are exposed to radiation from cosmic rays and secondary scattered rays generated by reactions with air or aircraft. For aircrews, radiation safety management is based on the exposure dose calculated using a space-weather environment simulation. However, the exposure dose varies depending on solar activity, altitude, flight path, etc., so measuring by route is more suggestive than the calculation. In this study, we developed an instrument to measure the cosmic radiation dose using a general-purpose Si sensor and a multichannel analyzer. The dose calculation applied the algorithm of CRaTER (Cosmic Ray Telescope for the Effects of Radiation), a space radiation measuring device of NASA. Energy and dose calibration was performed with Cs-137 662 keV gamma rays at a standard calibration facility, and good dose rate dependence was confirmed in the experimental range. Using the instrument, the dose was directly measured on the international line between Dubai and Incheon in May 2023, and it was similar to the result calculated by KREAM (Korean Radiation Exposure Assessment Model for Aviation Route Dose) within 12%. It was confirmed that the dose increased as the altitude and latitude increased, consistent with the calculation results by KREAM. Some limitations require more verification experiments. However, we confirmed it has sufficient utilization potential as a cost-effective measuring instrument for monitoring exposure dose inside or on personal aircraft. 비행시 승무원이나 승객은 우주방사선과 공기나 비행기 기체와 반응하여 발생한 2차 산란선 등에 의해 피폭을 받게 된다. 항공기 승무원의 경우 우주기상 환경 시뮬레이션을 이용하여 계산된 피폭선량으로 방사선 안전관리를 적용받고 있다. 하지만, 태양활동이나 고도, 비행경로 등에 따라 피폭선량이 가변적이어서 계산법보다는 항로별 측정하는 것이 권고되고 있다. 본 연구에서는 범용 Si 센서와 다중채널파고분석기를 이용하여 우주방사선 선량을 측정할 수 있는 선량계를 개발하였다. 선량계산은 미우주항공국의 우주방사선 측정장비인 CRaTER(Cosmic Ray Telescope for the Effects of Radiation)의 알고리즘을 적용하였다. 표준 교정시설에서 Cs-137 662 keV 감마선으로 에너지 및 선량교정을 시행하였으며, 실험 범위에서 선량률 의존성이 없음을 확인하였다. 제작된 선량계를 이용하여 2023년 5월 두바이 인천 구간의 국제선에서 직접 선량을 측정한 결과 국내 우주방사선 선량평가코드(KREAM; Korean Radiation Exposure Assessment Model for Aviation Route Dose)로 계산된 결과와 12% 이내로 비슷하게 나타났으며, 고도와 위도가 높아짐에 따라 계산결과와 동일하게 선량이 증가하는 것을 확인하였다. 좀 더 많은 실증적 검증 실험이 요구되는 제한점은 있지만, 항공기 내 또는 개인 피폭선량 모니터링에 가성비가 우수한 선량계로 충분한 활용 가능성을 확인하였다.

X-선 저장 BaFBr_1-xI_x:Eu²⁺, Na⁺ 형광체의 제조 및 특성

천종규,김성환,김찬중,김완,강희동,김도성,서효진,도시홍,Cheon, Jong-Kyu,Kim, Sung-Hwan,Kim, Chan-Jung,Kim, Wan,Kang, Hee-Dong,Kim, Do-Sung,Seo, Hyo-Jin,Doh, Sih-Hong 한국센서학회 2002 센서학회지 Vol.11 No.1

The forming conditions of X-ray storage phosrhors $BaFBr_{1-x}I_x:Eu^{2+}$, $Na^+$ have been investigated, and measured the PSL emission spectra and its intensity, fading characteristics and does dependence of the prepared phosphors. These characteristics were compared with those of commercial image plate (ST-III) obtained from Fuji Photo Film Co. The optimal preparing conditions of $BaFBr_{1-x}I_x:Eu^{2+}$, $Na^+$ Phosphor were 0.5 mol% of $EuF_3$, 4.0 mol% of NaF and composition ratio x=0.3, and the sintering temperature were $950^{\circ}C$ in $H_2$ atmosphere. When the composition ratio x was equal to 0, the spectral range of the luminescence of $BaFBr_{1-x}I_x:Eu^{2+}$, $Na^+$ phosphor was $365{\sim}420\;nm$, and its maximum luminescence intensity appeared at 390 nm. When composition ratio x was not equal to 0, the wavelength ranges and peak of the spectra were shifted to the longer wavelength with the growth of composition ratio x. A good linearity was shown between the PSL intensity and X-ray irradiation dose. The phosphor sample with x=0.3 exhibited better fading characteristics than that of other $BaFBr_{1-x}I_x:Eu^{2+}$ phosphor samples, and the fading characteristics of the PSL intensity at room temperature were shown poorer with increasing $I^-$ ion concentration. The lattice constant of the phosphor becomes larger with increasing the $I^-$ ion concentration. X-선 저장 형광체 $BaFBr_{1-x}I_x:Eu^{2+}$, $Na^+$의 조성 조건을 조사하고, 제조한 형광체의 광자극발광 강도, 스펙트럼, fading 특성 및 선량의존성을 조사하였다. 그리고 이 특성을 상업적으로 시판하고 있는 일본 부사(富士)사진필름회사 제품 영상판(ST-III)의 특성과 비교하였다. $BaFBr_{1-x}I_x:Eu^{2+}$, $Na^+$ 형광체의 최적 제조 조건은 $Eu_F3$ 0.5mol%, NaF 4.0mol% 그리고 조성비 x=0.3 이었으며, 소결온도는 수소 분위기에서 $950^{\circ}C$이었다. 조성비 x=0일 때 $BaFBr_{1-x}I_x:Eu^{2+}$, $Na^+$ 형광체의 스펙트럼영역은 $365{\sim}420\;nm$이었고, 최대 발광강도는 390 nm 이었다. $x{\neq}0$일 때 스펙트럼의 파장영역과 피이크 파장은 조성비 x가 증가할수록 장파장쪽으로 이동하였다. X-선 조사선량과 PSL 강도 사이에는 좋은 직선성을 나타내었다. 형광체의 fading 특성은 x=0.3일 때 가장 좋았으며, $I^-$ 이온의 농도가 증가할수록 저하되는 경향을 나타내었다. 또한 $BaFBr_{1-x}I_x:Eu^{2+}$ 격자상수는$I^-$이온의 농도가 증가할수록 커졌다.

X-선 저장 BaFBr1-xIx:Eu2+,Na+ 형광체의 제조 및 특성

천종규,김성환,김찬중,김완,강희동,김도성,서효진,도시홍 한국센서학회 2002 센서학회지 Vol.11 No.1

The forming conditions of X-ray storage phosphors BaFBr1-xIx:Eu2+,Na+ have been investigated, and measured the PSL emission spectra and its intensity, fading characteristics and does dependence of the prepared phosphors. These characteristics were compared with those of commercial image plate (ST-Ⅲ) obtained from Fuji Photo Film Co. The optimal preparing conditions of BaFBr1-xIx:Eu2+,Na+ phosphor were 0.5 ㏖% of EuF3, 4.0 ㏖% of NaF and composition ratio x = 0.3, and the sintering temperature were 950 ℃ in H2 atmosphere. When the composition ratio x was equal to 0, the spectral range of the luminescence of BaFBr1-xIx:Eu2+,Na+ phosphor was 365∼420 ㎚, and its maximum luminescence intensity appeared at 390 ㎚. When composition ratio x was not equal to 0, the wavelength ranges and peak of the spectra were shifted to the longer wavelength with the growth of composition ratio x. A good linearity was shown between the PSL intensity and X-ray irradiation dose. The phosphor sample with x=0.3 exhibited better fading characteristics than that of other BaFBr1-xIx:Eu2+ phosphor samples, and the fading characteristics of the PSL intensity at room temperature were shown poorer with increasing I- ion concentration. The lattice constant of the phosphor becomes larger with increasing the I- ion concentration. X-선 저장 형광체 BaFBr1-xIx:Eu2+,Na+의 조성 조건을 조사하고, 제조한 형광체의 광자극발광 강도, 스펙트럼, fading 특성 및 선량의존성을 조사하였다. 그리고 이 특성을 상업적으로 시판하고 있는 일본 富士사진필름회사 제품 영상판(ST-Ⅲ)의 특성과 비교하였다. BaFBr1-xIx:Eu2+, Na+ 형광체의 최적 제조 조건은 EuF3 0.5mol%, NaF 4.0mol% 그리고 조성비 x=0.3 이었으며, 소결온도는 수소 분위기에서 950℃ 이었다. 조성비 x=0일 때 BaFBr1-xIx:Eu2+,Na+ 형광체의 스펙트럼영역은 365∼420 nm 이었고, 최대 발광강도는 390 nm 이었다. x≠0일 때 스펙트럼의 파장영역과 피이크 파장은 조성비 x가 증가할수록 장파장쪽으로 이동하였다. X-선 조사선량과 PSL 강도 사이에는 좋은 직선성을 나타내었다. 형광체의 fading 특성은 x=0.3일 때 가장 좋았으며, I- 이온의 농도가 증가할수록 저하되는 경향을 나타내었다. 또한 BaFBr1-xIx:Eu2+ 격자상수는 I- 이온의 농도가 증가할수록 커졌다.

Multi-Segment Position-Sensitive Detector for an X-ray Imaging Crystal Spectrometer

천종규,문명국,이창희,Shraddha S. Desai,남욱원,Sang Gon Lee,Jun Gyu Bak,강희동 한국물리학회 2009 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.54 No.2

A two-dimensional segmented position sensitive detector (PSD) as a part of an X-ray imaging crystal spectrometer (XICS) for use in tokamak plasma experiments was developed. It is based on a multi-wire proportional counter (MWPC) using a delay-line readout method. The MWPC, necessary for recording plasma image data, provides the combined advantages of low neutron radiation sensitivity and large sensitive detection area. The fabricated PSD for the XICS is a four-segment MWPC that can be used in intense X-ray photon environments.

Development of cryogenic thermoluminescence measurement system and performance test on Na2W2O7 single crystal

천종규,Kim Seonghwan,PANDEY INDRA RAJ,김홍주 한국물리학회 2022 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.81 No.8

In this study, we developed a cryogenic thermoluminescence (TL) measurement system and evaluated its performance. A graphical user interface-based data acquisition software is programmed to control the whole system, which includes the thermostat, photomultiplier tube, and counter. To test the measurement system, we use Na2W2O7 (NWO) crystal. The NWO crystal was grown with a conventional Czochralski system. At room temperature (300 K), a broadband emission spectra of the crystal was obtained in the range of 340–790 nm under the excitation of a 280 nm light emitting diode (LED) source. The glow curves of NWO crystals were measured from 9 to 300 K with the cryogenic TL measurement system developed in this study. Six glow peaks at 23, 35, 110, 143, 178, and 231 K were observed from 9 to 300 K. The measured glow curves were analyzed by computerized glow curve deconvolution technique. The activation energy, order of kinetics, frequency factor, and fgure of merit (FOM) for each peak were obtained. The calculated FOMs for all glow peaks were found to be less than 4%, which confrmed that the developed cryogenic TL measurement system works well.

Csl : Na 결정 육성과 섬광 특성

천종규 ( Jong Kyu Cheon ),김성환 ( Sung Hwan Kim ),김홍주 ( H J Kim ) 한국센서학회 2010 센서학회지 Vol.19 No.6

In this work, the scintillation properties of Csl:Na crystal were investigated as radiation detection sensor. This scintillation material was grown by a 2-zone vertical Bridgman method. Under X-ray excitation the crystal shows a broad emission band between 280 nm and 690 nm wavelength range, peaking at 413 nm. Energy resolution for 137Cs 662 keV y-rays of the crystal was measured to be 6.9 %(FWHM). At room temperature, the crystal exhibits three exponential decay time components. The fast and major component of scintillation time profile of the crystal emission decays with a 457 ns time constant. Absolute light yield of the crystal was estimated to be 53,000 ph/MeV using LAAPD. The sample crystal shows proportionality of 30% in the measured energy range from 31 to 1,333 keV. And the a/β~ ratio of the crystal was 0.14.

CsI:Gd 결정 육성과 섬광 특성

천종규 ( Jong Kyu Cheon ),김성환 ( Sung Hwan Kim ),김홍주 ( Hong Joo Kim ) 한국센서학회 2012 센서학회지 Vol.21 No.4

CsI:Gd crystal was grown by the Bridgeman method and its scintillation properties were investigated. The wavelength peak of the luminescence spectrum for the crystal excited by X-ray was 419 nm. The range of the spectrum was from 300 nm to 800 nm. The spectrum well matched to the quantum efficiency of a typical bi-alkali photo-multiplier tube(PMT). An energy resolution of 48.2 % was obtained for 662 keV γ-rays of 137Cs. The three decay times were obtained as a fast(557.4 ns, 42.2 %), intermediate (1.78 μs, 29.7 %) and slow (5.43 μs, 28.1 %) components, respectively.

조직 등가 섬광체를 이용한 계수형 선량계의 개발과 특성 평가

천종규 ( Jong Kyu Cheon ),김성환 ( Sung Hwan Kim ),김홍주 ( Hong Joo Kim ) 한국센서학회 2014 센서학회지 Vol.23 No.1

A dosimeter using tissue-equivalent scintillator by photon-counting method was developed and evaluated in its performance. The dosimeter is portable and can be operated by low power from lap-top computer. A data-acquisition software of the dosimeter system was developed by Labwindows/CVI based on Windows. The energy to channel ratio for energy calibration was 0.839 keV/ch. obtained from pulse height spectrum of 137Cs and 60Co gamma-ray. Using the dosimeter system, the absorbed dose of environmental radiation in Gyungju was 0.18 Sv/h.

단일 보너구와 TLD-600 및 TLD-700을 이용한 Cf-252의 중성자 에너지 스펙트럼 평가

김성환 ( Sung Hwan Kim ),천종규 ( Jong Kyu Cheon ),이재진 ( Jae Jin Lee ),남욱원 ( Uk Won Nam ) 한국센서학회 2013 센서학회지 Vol.22 No.3

We designed a single polyethylene bonner sphere with several thermo-luminescence dosimeters (TLD), for measurement of neutron energy spectrum. For the separation of the neutron dosage in the neutron-gamma mixed field, we used 21 ea TLD-600s and TLD-700s, respectively. Because, TLD-600 is sensitive to neutron and gamma rays, and, TLD-700 is sensitive only to gamma-rays, we could determine the each dose[U1] by neutron and gamma rays. The neutron response function of the bonner sphere with TLDs was calculated by MCNPX (ver. 2.5.0) Monte Carlo simulation in the energy range from 10-1 to 20 MeV. For the Cf-252 standard neutron source in KRISS, we could estimate the neutron energy spectrum by unfolding method using the response function.

고분자 구조 분석을 위한 소각 X-선 산란 시스템

유석근,심운보,전혜진,천종규,문명국,이창희,송현훈 한국고분자학회 2008 한국고분자학회 학술대회 연구논문 초록집 Vol.33 No.2