$\circ$ 한국지질자원연구원에 1 MV 가속기 질량분석기 구축 완료
$\circ$ 연대측정 뿐 아니라 지구환경변화연구에 폭 넓게 활용할 것을 목적으로 함
$\circ$ 목재, 탄산칼슘, 토양, 뼈, 철, 토기, 대기 등의 시료 측정가능
$\circ$ $^{10}Be,\;^{26}Al$ 등의 다른 우주선 유발 동위원소도 측정 가능
$\circ$ 최대 측정가능 연대: 50,000년
$\circ$ 연간 1,000개의 연대 시료측정 능력 확보
Abstract
▼
The report of Intergovernmental Panel on Climate Change(IPCC) which was held in 2001 with around 3,000 participants shows that the average temperature of the earth during 21th century will rise with $5.8^{\circ}C$ and sea level 88 cm. Nowadays, global environmental change has been one of
The report of Intergovernmental Panel on Climate Change(IPCC) which was held in 2001 with around 3,000 participants shows that the average temperature of the earth during 21th century will rise with $5.8^{\circ}C$ and sea level 88 cm. Nowadays, global environmental change has been one of the most serious international problems. To research the global environmental change, the investment to the basic infrastructure for the research is essential, and could not be delayed anymore. Korea Ministry of Science and Technology(MOST) has supported projects to install large facilities to study global environmental change and earth science.
As one of the projects, "The Project for Installation of Accelerator Mass Spectrometer" was launched on March in 2005. After the designing and manufacturing for two years, an 1 MV accelerator mass spectrometer(AMS) has been installed this year at Korea Institute of Geoscience and Mineral Resources on the purpose of application to earth science such as geology, oceanography, sedimentology, atmosphere science and dendrochronology as well as archeology and history. Since this AMS system has ability to measure not only radiocarbon, but also beryllium-10 and aluminium-26, the application to earth science could be expanded to advanced research subjects. The installation room was totally renovated at the very beginning of this year and the accessary facilities such as air compressor, water cooling system and air conditioners were installed onsite.
The sample pretreatment system including a reduction system, a carbonate treatment system, chemical and physical treatment systems has been also set up. These pretreatment system provides us the ability to treat around 1,000 organic, carbonate, soil, sediment, bone, iron and pottery piece, and air samples per year.
The carbonate line was composed of reaction tube of carbonate and phosphoric acid, transfer vessel, two traps, and vacuum line. The main vacuum line was made by Pyrex glass to avoid corrosion by usage of acid. And vacuum system employed a turbo molecular pump(TMP) as the main evacuation unit and a dry pump for rough pumping of system and backing of the TMP. The dry pump was chosen ta prevent whole system from contamination of pump oil. Typical vacuum state of the system is $2{\times}10^6$ torr. The yield of carbon dioxide gas from calcium carbonate was higher than 90 % in normal case and the adulteration of modern carbon was lower than $1{\times}10^{-4}$.
Reduction system for synthesis of graphite from carbon dioxide gas was fabricated. This system was directly connected to an elemental analyser(EA) at which combustible sample is burned, and carbon dioxide from the sample is transferred to the reduction line and trapped for reduction process. This system has five reduction tubes to treat five samples at once. A furnace to heat the reduction tubes to $620^{\circ}C$ during reduction process was made by a Kanthal heater and a silver ingot to minimize the temperature deviation between reduction tubes. All the parameters such as temperature, pressure of each tube are monitored by a personal computer automatically. The PC detects the completion of the reaction and turns off the furnace automatically. Reduction time of this system is $130{\sim}150$ minutes. Typical vacuum state of the system is $2{\times}10^{-7}$ torr and the reduction yield is higher than 90%.
Installation of 1 MV AMS took 3 months. Ion source of this machine is Cs sputtering type. A carrousel is provided at this ion source for 50 sample roading at once and an actuator inserts targets into the target position one by one automatically. Typical sample exchanging time was 20 seconds. Syltherm(Dow Chemical Company) was used for cooling the target holder. Target bias and extraction voltage were 7 kV and 28 kV, respectively. Two turbo pumps evacuate the source ta $7{\times}10^{-8}$ torr. The maximum carbon beam current from the source was higher than 100 ${\mu}A$. Typical carrousel exchange time was 30 minutes.
$90^{\circ}$ injector magnet has two functions. One is selecting of isotope having set mass and the other one is fast bouncing between selected isotopes to measure them sequentially. The maximum bending ability is 9.8 $amu{\cdot}MeV$ and bending radius is 400 mm. The maximum bouncing frequency is 100 Hz and the maximum bouncing voltage is 3,000 V.
The 1 MV tandetron is Cockcroft-Walton type and the Q-factor was around 930 at the radio frequency of 50 kHz. However, this condition slightly depends on the $SF_6$ gas pressure. Ar gas is used to strip passing ions, and beam transport yield for carbon beam was around 47%. A generating volt meter(GVM) and the slit control modes were provided to stabilize the terminal voltage.
Multi elemental mass analyzing magnet has bending ability of 63 $amu{\cdot}MeV$, bending angle of $90^{\circ}$ and bending radius of 850 mm. This part is 6.5 ton heavy and it is the heaviest part of this AMS system. The magnet current is available up to 300 A and the gap between poles is 50 mm. This magnet separates isotopes and makes the measurement of stable isotopes with Faraday cups possible.
Radioisotopes are analyzed again by their energy at a electrical spherical analyzer(ESA). The ESA has bending angle of $120^{\circ}$, radius of 650 mm and gap between electrodes of 25 mm. The maximum available bias voltage is 60 kV.
The backgrounds of this system were found to be $2.3{\times}10^{-15}$ for carbon measurement, $2.7{\times}10^{-14}$ for aluminium measurement, and $1.7{\times}10^{-14}$ for beryllium measurement. And the precision of isotope ratio were 0.5% for carbon and 3% for aluminium and beryllium.
We have made steady progress in the project through this year in spite of several unexpected accidents, and most of goals of this year were achieved successfully. Sample treatment capacity for radiocarbon measurement will be enlarged in the next year by fabrication of additional reduction facility. And pretreatment system for Be and Al samples will be also installed.
This 1 MV AMS and the related facilities will be applied to study on the global environmental change. It is expected that this new facility could provide the basic technical supports for research fields of terrestrial and marine environment changes in our country.
목차 Contents
- 제 1 장 사업의 개요...25
- 제 1 절 사업의 목적...25
- 제 2 절 사업의 필요성...25
- 1. 경제.사회.기술적 중요성...25
- 2. 사업의 필요성...30
- 제 2 장 국내외 기술개발 현황...31
- 제 1 절 국내의 기술개발 현황...31
- 1. 국내의 방사성 탄소 연대측정 연구...31
- 2. 국내의 가속기 질량분석법의 기술개발 현황...31
- 제 2 절 국외의 기술개발 현황...32
- 1. 국외의 방사성탄소연대측정법의 개발...32
- 2. 국외의 가속기 질량분석법의 현황...33
- 제 3 장 연구개발수행 내용 및 결과...35
- 제 1 절 서론...35
- 제 2 절 본론...37
- 1. 실험실 정비 및 보조설비의 설치...37
- 가. 실험실 보강공사...37
- 나. 보조설비의 설치...39
- 2. 실험...39
- 가. 물리적 전처리...39
- 나. 화학적 전처리...42
- (1) 목재시료의 화학적 전처리법...43
- (2) 토양시료의 화학적 전처리법...45
- (3) 뼈시료의 화학적 전처리법...47
- (4) 대기시료의 화학적 전처리법...48
- (5) 베릴륨시료 전처리법...49
- (6) 알루미늄 시료 전처리법...50
- 다. 탄산칼슘시료 처리라인 제작...50
- 라. 연소장치...54
- (1) 연소장치의 원리...54
- (2) 시료에 따른 연소법...55
- 마. 흑연화장치의 제작...58
- 바. 표적 제작...61
- 사. 가속기 질량분석기의 도입 및 구축...63
- (1) 공장테스트...63
- (2) 도입 및 설치...64
- (3) 인수테스트...98
- 3. 결과 및 해석...102
- 가. 화학적 전처리법 평가...102
- (1) 목재시료의 전처리법 성능검증...102
- (2) 토양시료의 진처리법의 개선 및 방사성탄소 측정...103
- (3) 뼈시료 처리법의 검증...106
- (4) 대기시료 처리법의 검증...107
- (5) 철기시료 처리법...107
- 나. 탄산칼슘시료 처리장치의 성능평가 결과...108
- 다. 흑연화장치의 성능평가 결과...112
- 라. 가속기 질량분석기의 도입 및 구축...115
- (1) 공장테스트 결과...115
- (2) 표적의 특성평가...116
- (3) 인수테스트(Acceptance test) 결과...116
- 3 절 결론...123
- 제 4 장 목표달성도 및 관련분야에의 기여도...126
- 제 1 절 목표달성도...126
- 1. 최종 연구목표의 달성도...126
- 2. 연차별 목표의 달성도...127
- 제 2 절 관련분야에의 기여도...128
- 제 5 장 연구개발결과의 활용계획...129
- 제 1 절 연구원 내부 활용계획...129
- 제 2 절 연구원 외부 활용계획...129
- 제 6 장 참고문헌...131
- Appendix A. 가속기 제원...136
- Appendix B. 사업의 중요 일정표...139
- Appendix C. 제2차 AMS workshop(2007년 6월 1일)...140
- Appendix D. 제2회 동아시아 AMS conference (2nd East Asia AMS conference, EAAMS-2)(2007년 10월 22$\sim$23일)...143
- Appendix E. 가속기 질량분석기 가동식(2007년 11월 13일)...147
※ AI-Helper는 부적절한 답변을 할 수 있습니다.