Accelerator mass spectrometry (AMS) principles and some applications Today s lecture:

Transcription

1 Accelerator mass spectrometry (AMS) principles and some applications Today s lecture: Introduction to C and AMS tandem-ams versus single stage AMS (SSAMS) Introduction ti to applications of fams Instructions for your assignment: * literature re study * preparing a scientific poster * oral presentation We will decide topics, groups, deadlines and days for oral presentation today!

2 Accelerator mass spectrometry (AMS) principles and some applications Archeology Geology 3 Medicine H Food chemistry C 36 Radiation protection 26 Al Cl Ecology 59 Ni Radioecology Aerosol science Microdosing 10 Be 129 I

3 How is C created? Modern carbon 99% 12 C 1% 13 C % C CO 2 O 2 O 2 CO 2 Cosmic rays + C (carbon-) N (nitrogen-) CO 2 C + O 2 CO O 2 CO 2 O 2 C N + -radiation T 1/2 =5730 years

4 How to measure C? (T 1/2 =5730 years) Modern carbon: 99% 12 C 1% 13 C % C 1 gram of modern carbon C N + -radiation Decay measurement: several days of measuring time 1 g carbon decays/minute million atoms AMS measurement: AMS measurement: < 1 hour of measuring time 1 mg carbon

5 Why not conventional mass spectrometry? BR=mv/q=(2mE) 1/2 /q The C signal will drown in a background of interfering isobars (ions with M=, e.g. 13 CH)!

6 Accelerator Mass Spectrometry (AMS) removes isobars! Ion source Detector The picture shows an example of a large 5 MV Tandem AMS system

7 New development: Single Stage AMS (SSAMS) instead of Tandem AMS We have SSAMS at Lund University Much smaller! Much cheaper!

8 In your poster you should describe tandem AMS or single stage AMS (SSAMS). You should also select an application of AMS to present.

9 Tandem-AMS Ion source with carbon samples 3 MV tandem accelerator Dipolmagnets Velocity filter Particle detector Mass separator Measures C/ 12 C: gives activity ( age) Measuring time: ca 20 min/sample Detection limit: <1 attomole (10 18 mole) C Sample size: 10 g - 1 mg carbon

10 Tandem AMS removal of isobars BR=mv/q=(2mE) 1/2 /q C C 13 C C C q+, C 13 CH 13 CH 12 CH 12 2 CH 2 CH 2 No N! 13 CH +, 13 CH 2+ No 13 CH 3+ or higher! h Important properties: Negative ion source: suppresses certain atomic isobars ( N) Stripping process: breaks up molecules High energy: every particle can be identified

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12 Single Stage AMS (SSAMS) Single Stage AMS (SSAMS) The system we have at Lund University

13 He (or Ar) gas stripper Changes charge state from negative to positive Breaks up all molecular isobars (e.g. 13 CH in the C beam) Dipole magnet, Selects m. E/q 2 q=+1 q+1 Faraday Electrostatic Analyzer (ESA) Selects E/q cups Measure 12 C +, 13 C + Detector Measures C kv acceleration Dipole magnet, Switches 12 C / 13 C / C Selects m. E/q 2 Electrostatic Analyzer (ESA) Acts as a switch between the two ion sources Selects E/q Ion sources produce negative ions (q= 1) from one of the ion sources

14 Sample holders Sample holders with carbon samples Ion source wheel for 40 carbon samples

15 Cs sputtering ion source producing singly charged negative ions

16 He (or Ar) stripper 250 kev acceleration tube Electrostatic analyser Ion source

17 Control room

18 Applications of AMS Natural C Modern carbon 99% 12 C 1% 13 C % C CO 2 O 2 O 2 CO 2 Cosmic rays + N C CO 2 C + O 2 CO O 2 CO 2 O 2 C N + -radiation T 1/2 =5730 years

19 C in atmospheric CO 2 until today Something drastic happened in the 1900 s! C ( ) 400 n + N C + p C+O 2 CO Calendar year

20 C in atmospheric CO 2 (clean air) year C-specific activity it C ( ) INTCAL98 Vermunt, CO 2 Schauinsland, CO 2 Måryd, Juncus Bomb-effect Absorption in biosphere and oceans 400 Bq/kg 300 Bq/kg Combustion of fossil fuels 226 Bq/kg Calendar year

21 C in atmospheric CO 2 (clean air) year C-specific activity it C ( ) INTCAL98 Vermunt, CO 2 Schauinsland, CO 2 Måryd, Juncus Bomb pulse dating 400 Bq/kg 300 Bq/kg Bq/kg Calendar year

22 Bomb C some applications Uptake in biosphere and oceans 4 C ( ) INTCAL98 Vermunt, CO 2 Schauinsland, CO 2 Måryd, Juncus Studies of the carbon cycle turnover times in biological tissues Calendar year Dating - forensic science - retrospective cell dating in man

23 Bomb C some applications i Checking vintages of wine Burchuladze et al, 1989 Zoppi et al, 2004 Tracking narcotics Zoppi, 2004 Identification of furs of illegaly hunted animals Geyh, 2001

24 Bomb C some applications in man Growth rate of gallstones Druffel & Mok, 1983 Age of senile plaques in Alzheimer s disease Lovell et al, 2002 Retrospective cell dating in the brain Spalding et al, 2005 Dynamics of fat cell turnover Spalding et al, 2008 Carbon turnover in the human eye lens crystallines Lynnerup et al, 2008 Dating of blood vessel plaques Goncalves et al, 2010

25 Are there some more local variations? Natural C Bomb C What influences the contemporary C specific activity??? Coal lfired power plants Volcanoes Fossil carbon Traffic

26 Nuclear power generates C! Turbine Generator Steam Condensor Fuel rods Sea water Reactor water

27 Nuclear power C C is produced in CO 2 the fuel reactor water construction materials Waste C SFR C Waste disposal facility

28 Nuclear power C indeed gives locall C variations i in the vicinity of a reprocessing plant for spent nuclear fuel 1200 C (per rmille) Grass 1,5 km from Sellafield,UK 447 Bq/kg C Calender year 226 Bq/kg C

29 Aerosols and their effects light 5-10 µm scattering 3-5 µm 2-3 µm 1-2 µm light absorption heat radiation µm Cloud formation zuerich.ch/gud/de/index/umwelt/luft/schadstoffe/feinstaub.html Aerosols can affect: human health the Earth s climate

30 Where do the carbonaceous aerosol stem from? 12 Contemporary C/ 12 C ratios No C Recently Millions of years ago C decay

31 Accelerator mass spectrometry - Some more applications 26 Al 41 Ca 129 I C 7 Be Cl Ni 63 Ni 3 H 10 Be Cosmic rays Solar activity Earth magnetic field Meteorites The moon The atmosphere The climate Glaciers Oceanography Medicine Biology Archeology Geology Nuclear physics Material science Radiation protection Rdi Radioecology...

32 Literature study, poster and oral presentation on AMS The assignment includes: a literature t study, preparing p a poster, an oral presentation (about 10 minutes) and an oral opposition on one of the co student s posters (about 5 minutes). The work is performed din pairs.

33 Possible topics Choose one of the following suggestions of AMS applications, or make a suggestion of your own (see e.g. in the paper by Fifield) AMS in archaeology Cosmic ray studies and calibration in radiocarbon dating AMS in geology AMS in oceanography AMS in glaciology Extraterrestrial applications of AMS AMS in medical technology (e.g. microdosing and mass balance studies) AMS for studies in occupational medicine Bombpeakdating (e.g. forensic science, regenerative medicine) AMS in aerosol science C from nuclear power C in source apportionment of atmospheric aerosol

34 The poster: a (scientific) seduction operation!!! - One should understand immediately what your poster is about Message clear and quickly visible Key ideas (only the essential) Logical organisation of the poster - Goal: to attract people and make them curious! Eye-catching title Visual layout Pictures and figures preferably to text Text font big enough to be read easily from a distance

35 Check list for a good poster 1. Overview Is the poster eye-catching? Are the structures and optical elements helpful in guiding you through the poster? Is there an overriding logical concept underpinning the structure of the poster? 2. Take home message Is the main message immediately visible? Is the relevance of the problem immediately visible? 3. Text Is the text on the poster inviting to read? Is the text well compressed to the essentials? Is the language simple and clear? 4. Figures, Graphs Are the figures and Graphs on the poster inviting to read? Are the Legends clear and helpful? Are the graphs or tables essential for the poster? 5. Interaction Does the poster make me feel like discussing with the author?

36 Each poster should oudinclude: An appropriate it title Names of authors Affiliations of authors The following sections Introduction (in this section you provide an adequate background and state the objectives of the study) Accelerator mass spectrometry (this is the Method section where you describe the principle of the AMS: tandem AMS or SSAMS, preferably with pictures) Your topic (here you describe your topic with proper references) Summary and conclusions References at the end of the poster (see previous slide)

37 Literature suggestions to begin with (find the articles at the web in through the library) Hellborg R, Skog G: Accelerator mass spectrometry. Mass Spectrometry Reviews 27 (2008) Fifield KF: Accelerator mass spectrometry and its applications. Reports on Progress in Physics 62 (1999) K Stenström, M Sydoff, S Mattsson: Microdosing for early biokinetic studies in humans. Radiation Protection Dosimetry 139 (2010) ,doi:101093/rpd/ncq029 You may need further references for your specific topic. If you need help, contact Nolwenn (nolwenn.perron@nuclear.lu.se, office: B216)

38 References in the poster (not more than 10!) Example: Reference to a paper pp by Purser and co authors, published in One important discovery was that N does not form negative ions (Purser et al., 1977). References are alphabetically ordered in the following format: Authors. Publishing year. Title of paper. Journal title journal number: page numbers. Purser KH, Liebert RB, Litherland AE, Benkens RP, Gove HE, Bennett CL, Clover MR, Sondheim WE An attempt to detect stable N ions from a sputter ion source and some implications of the results for the design of tandems for ultra sensitive carbon analysis. Rev Phys Appl 12: Include references and do not copy what anyone else has written (produce your own text from the knowledge you gain when reading articles etc). This is very important (copying someone else s text is considered as cheating).

39 URKUND All posters should be submitted to URKUND to protect your own and others copyrights! ih Include references and For information and instructions, see and Posters should be submitted to Nolwenn surkund address:

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42 Td Today: find someone to work with, Important dates make your choice of topic and tell Nolwenn, preferably before the end of the class, or to 13 February: Deadline for poster submission to Nolwenn Deadline for poster submission to URKUND Comments will be made and groups have the possibility to send a modified version until the 16 February 16 February: Nolwenn distributes posters for opposition Week beginning 20 February: Oral presentation and opposition (Decide date today!) Times decided: Tue 22/ (room H422)

43 Please use spelling and grammar check before submitting the poster!!!