Sub at phys 2012 - Kärnfysik | Kärnfysik · ‐principles and some ......
Transcript of Sub at phys 2012 - Kärnfysik | Kärnfysik · ‐principles and some ......
Accelerator mass spectrometry (AMS) ‐ principles and some applications
Today’s lecture:
•Introduction to 14C and AMS – tandem-AMS versus single stage AMS (SSAMS)
I t d ti t li ti f AMS•Introduction to applications of AMS
•Instructions for your assignment: * literat re st d* literature study * preparing a scientific poster* oral presentation
We will decide topics, groups, deadlines and
days for oral presentation today!
Accelerator mass spectrometry (AMS)
• Archeology
‐ principles and some applications
3H
cheology• Geology • Medicine
14C36Cl
3H • Food chemistry• Radiation protection• Ecology26Al
59Ni• Ecology• Radioecology•Aerosol science
Al
129I10B
•Microdosing
10Be
H i 14C d?How is 14C created?
O214CO2Modern carbon
Cosmic rays+ 14C (carbon-14)
O2
2
14CO2
2
14CO2 14C + O214CO2
99% 12C1% 13C
10-10% 14C
14N (nitrogen-14)
O2
O214CO2
2 2
14C 14N + -radiationT 5730T1/2=5730 years
How to measure 14C? (T1/2=5730 years)
”Modern”carbon:
How to measure C? (T1/2 5730 years)
ode c bo :99% 12C1% 13C
Decay measurement:• several days of measuring time• 1 g carbon
14 decays/minute
10-10 % 14Cg
50 000 million atoms
14 decays/minute1 gram of modern carbon 14C 14N + -radiation
AMS measurement:AMS measurement:• < 1 hour of measuring time• 1 mg carbon
Why not conventional mass spectrometry?Why not conventional mass spectrometry?
BR=mv/q=(2mE)1/2/q
The 14C signal will drown in a background of interfering isobars
(i i h M 14 13CH)!(ions with M=14, e.g. 13CH)!
Accelerator Mass Spectrometry (AMS) removes isobars!
Ion source
Detector
The picture shows an example of a large 5 MV Tandem AMS system
New development: Si l S AMS (SSAMS) i d f T d AMSSingle Stage AMS (SSAMS) instead of Tandem AMS
We have SSAMS at Lund University
• Much smaller!• Much cheaper!• Much cheaper!
In your poster you should describetandem AMS
orsingle stage AMS (SSAMS)single stage AMS (SSAMS).
You should also select an application of AMS to present.
Tandem-AMSTandem-AMS
Ion sourcewith carbon
3 MV tandem accelerator
Velocitywith carbonsamples
Dipolmagnets
Velocityfilter
Particledetector
Mass separator
detector
• Measures 14C/12C: gives activity ( age)• Measuring time: ca 20 min/sample• Detection limit: <1 attomole (10–18 mole) 14C• Sample size: 10 g 1 mg carbon• Sample size: 10 g - 1 mg carbon
Tandem‐AMS – removal of isobarsBR=mv/q=(2mE)1/2/q
14C3+
14Cq+14C–
12C–
13C–Cq ,
13CH+, 13CH2+
No 13CH3+
hi h !
C13CH–
12CH2–
14C–
13CH–
12CH2–
Important properties:
or higher! CH2No 14N!
Important properties:•Negative ion source: suppresses certain atomic isobars (14N)•Stripping process: breaks up molecules•High energy: every particle can be identified
250 kV acceleration
He (or Ar) gas stripperChanges charge state from negative to positive
Dipole
accelerationg g f g pBreaks up all molecular isobars (e.g. 13CH in the 14C beam)
Dipolemagnet,
Switches 12C / 13C / 14Cl / 2
Dipole
Electrostatic
Selects m.E/q2magnet,Selects m.E/q2
q=+1 FaradayAnalyzer (ESA)Acts as a switch between
the two ion sources
q +1 ycups
Measure 12C +, 13C +the two ion sources
Selects E/q
,
Electrostatic Detector
Ion sources –Analyzer (ESA)
Selects E/q
DetectorMeasures 14C+
Ion sources produce negative ions (q=‐1)from one of the ion sources
Ion source wheel for 40 carbon samplesfor 40 carbon samples
Sample holdersSample holders with carbon samples
He (or Ar) stripper
250 keV
stripper
250 keV acceleration tube
Electrostatic
Ion source
Electrostatic analyser
Applications of AMSNatural 14C
O214CO2Modern carbon
Cosmic rays+
14N14C
O2
2
14CO2
2
14CO2 14C + O214CO2
99% 12C1% 13C
10-10% 14C
14N
O2
O214CO2
2 2
14C 14N + -radiationT 5730T1/2=5730 years
14C in atmospheric CO until today14C in atmospheric CO2 until today…
Something drastic happened
800
g ppin the 1900’s!600
(‰)
400
14C
(
n + 14N→ 14C + p
0
200 14C+O2→ 14CO2
-25000 -20000 -15000 -10000 -5000 0 5000
0
Calendar year
14C in atmospheric CO (clean air)C in atmospheric CO2 (clean air)year 1900‐2007 14C-specific
ti it800 INTCAL98
V t CO
activity
Absorption in 400 Bq/kg
600
Vermunt, CO2 Schauinsland, CO2 Måryd, Juncus
‰)
biosphere and oceans
400
14C
(‰
Bomb-effect300 Bq/kg
200Combustion of fossil fuels
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010
0fossil fuels 226 Bq/kg
Calendar year
14C in atmospheric CO (clean air)C in atmospheric CO2 (clean air)year 1900‐2007 14C-specific
ti it800 INTCAL98
V t CO
activity
400 Bq/kgb l
600
Vermunt, CO2 Schauinsland, CO2 Måryd, Juncus
‰)
Bomb‐pulsedating
400
14C
(‰
300 Bq/kg200
1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010
0 226 Bq/kg
Calendar year
Bomb 14C – some applicationsBomb‐14C – some applicationsUptake in biosphere and oceans
Studies of
Uptake in biosphere and oceans
• the carbon cycle• turnover times in biological 800 INTCAL98
tissues
400
600
Vermunt, CO2 Schauinsland, CO2 Måryd, Juncus
4 C (‰
)
Dating- forensic science0
200
1
- retrospective cell dating in man1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000 2010
Calendar year
B b 14C li iBomb‐14C – some applications
Checking vintages of wine Tracking narcotics
Z i 2004Identification of furs
Burchuladze et al, 1989Zoppi et al, 2004
Zoppi, 2004 of illegaly hunted animals
Geyh 2001Geyh, 2001
Bomb‐14C – some applications…
Growth rate
pp… 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 2008Spalding et al, 2008
Carbon turnover in the human eye lens crystallines
Lynnerup et al, 2008 Dating of blood vessel plaquesGoncalves et al, 2010
Are there some more localvariations?
Natural 14C Bomb‐14C
What influences the contemporary 14C specificcontemporary C specific
activity???C l fi d l t
Volcanoes
Coal fired power plants
Fossil carbonTraffic
Fossil carbon
Nuclear power generates14C!Nuclear power generates14C!Generator
Steam
Turbine
Generator
Fuel
SteamCondensor
Sea waterFuel rods
Sea water
Reactor water
Nuclear power‐14Cp14C is produced in
14CO • the fuel• reactor water• construction materials
14CO2
Waste
14C SFR
14CWaste disposal facility
Nuclear power‐14C indeedi l l14C i igives local14C‐variations…
in the vicinity of a i l freprocessing plant for
spent nuclear fuel
1200
800
1000Grass 1,5 km from Sellafield,UK
rmill
e)
447 Bq/kg C
400
600
14C
(per
0
200
226 Bq/kg C1940 1950 1960 1970 1980 1990 2000 20100
Calender year
226 Bq/kg C
Aerosols and their effects
lightscattering5-10 µm scattering
lightabsorption
5-10 µm
3-5 µm
heat radiation
µ
2-3 µm
1-2 µm
0 1 1 µmCloudformation
0.1-1 µm
http://www.stadt-
Aerosols can affect: human health
http://www.stadtzuerich.ch/gud/de/index/umwelt/luft/schadstoffe/feinstaub.html
the Earth‘s climate
Where do the carbonaceous aerosol stem from?
No 14CContemporary 14C/12C ratios12
12
14
12C/ C ratios12
Millions of years ago
Recently
14C decay
Accelerator mass spectrometry - Some more applications
• Cosmic rays
26Al
Cosmic rays• Solar activity• Earth magnetic field• Meteorites26Al
7Be14C
36Cl
3H
59N
• The moon• The atmosphere• The climate
10Be
Cl63Ni
59Ni
41Ca
• Glaciers• Oceanography• Medicine
129IC
• Biology• Archeology• Geology
N l h i• Nuclear physics• Material science• Radiation protection• R di l• Radioecology• ...
Literature study, poster and oral presentation on AMS
The assignment includes: lit t t d• a literature study,
• preparing a poster,p p g p ,• an oral presentation (about 10 minutes) and
l f h d ’• an oral opposition on one of the co‐student’s posters (about 5 minutes).
Th k i f d i iThe work is performed in pairs.
Possible topicsChoose 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
l• AMS in geology• AMS in oceanography• AMS in glaciology• AMS in glaciology• Extraterrestrial applications of AMS• AMS in medical technology (e.g. microdosing and mass balance gy ( g g
studies) • AMS for studies in occupational medicine • Bombpeak dating (e g forensic science regenerative medicine)• Bombpeak dating (e.g. forensic science, regenerative medicine)• AMS in aerosol science• 14C from nuclear powerp• 14C in source apportionment of atmospheric aerosol
The poster: a (scientific) seduction operation!!!
- One should understand immediately what your poster is aboutposter is about
Message clear and quickly visibleKey ideas (only the essential)Key ideas (only the essential)Logical organisation of the poster
- Goal: to attract people and make them curious!
Eye-catching titley gVisual layoutPictures and figures preferably to textT t f t bi h t b d ilText font big enough to be read easilyfrom a distance
Check‐list for a good poster1. OverviewIs 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 messageIs the main message immediately visible?Is the relevance of the problem immediately visible?
3 T t3. TextIs the text on the poster inviting to read?Is the text well compressed to the essentials?Is the language simple and clear?Is the language simple and clear?
4. Figures, GraphsAre the figures and Graphs on the poster inviting to read?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. InteractionDoes the poster make me feel like discussing with the author?
Each poster should include:ac poste s ou d c ude:
A i t titl• An appropriate title• Names of authors• Affiliations of authorsAffiliations 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 withdescribe 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)
Literature suggestions to begin with gg g(find the articles at the web in through the library)
H llb R Sk G A lHellborg R, Skog G: Accelerator mass spectrometry. Mass Spectrometry Reviews 27 (2008) 398‐427.
Fifield KF: Accelerator mass spectrometry and its applications. Reports on Progress in Physics 62 (1999) 1223‐1274.
K Stenström, M Sydoff, S Mattsson: Microdosing for early biokinetic studies in humans. Radiation Protection Dosimetry 139 (2010) 348‐352,doi:101093/rpd/ncq029 y p q
You may need further references for your specific topic. If you need help, contact Nolwenn ([email protected], office: B216)
References in the poster (not more than 10!)
Example:
Reference to a paper by Purser and co‐authors, published in 1977. p p y p“One important discovery was that 14N 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
bnumbers.
Purser KH, Liebert RB, Litherland AE, Benkens RP, Gove HE, Bennett CL, Clover MR, Sondheim WE 1977 An attempt to detect stable N‐ ions from a sp tter ion so rceSondheim WE. 1977. 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 12:1487–1492.
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).
URKUNDURKUND• All posters should be submitted to URKUND to protect your
d h ´ i h !own and others´ copyrights! • Include references and
f dFor information and instructions, see
http://www.urkund.com/int/en/student_information.aspand http://www.urkund.com/int/en/student_gorsahar.asp
Posters should be submitted to Nolwenn´s URKUND address: [email protected]
Important datesT d• Today:– find someone to work with, – make your choice of topic and tell Nolwenn, preferably before the end of themake your choice of topic and tell Nolwenn, preferably before the end of the
class, or email to [email protected].
• 13 February:13 February:– Deadline for poster submission to Nolwenn ([email protected])– Deadline for poster submission to URKUND
( )([email protected])
Comments will be made and groups have the possibility to send a modifiedversion until the 16 Februaryversion 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 22/2 13-15 (room H422)