Download Potential of AMS for Quantifying Long

Experimental Nuclear Astrophysics with
Accelerator Mass Spectrometry
Anton WALLNER
for the
VERA Laboratory
Institut für Isotopenforschung und Kernphysik
Universität Wien
Austria
Applications of AMS to Astrophysics
1. Search for live radioisotopes as signatures of a
nearby SN (60Fe, 244Pu, ...)
2. Meteorites
-
cosmic ray exposure, ...
3. Recent nucleosynthesis
-
-ray astronomy (live radionuclides)
4. Solar system abundance
-
early solar system (presolar, extinct radionuclides)
solar system abundance now
nucleosynthesis models
Overview
• What is AMS (Accelerator Mass Spectrometry)
• VERA (Vienna Environmental Research Accelerator)
• Applications
– Search for SN-produced signals on Earth
– Cross-section measurements
What is AMS ?
Mass spectrometric method
• Sample material is sputtered in negative ion source
• Low energy mass separation
• Tandem accelerator
– stripping to positive ions (molecule destruction)
– high particle energies for identification
• High energy mass separation
• Particle identification (detector + Faraday cups)
• Isotopic ratio measurements: typically 10-12 – 10-15
• Mass spectrometry: needs isobar separation
• …(TOF, gas-filled magnet, deltaTOF) …
VERA
figure
VERA
negative
ions
positive
ions
stripping and molecule dissociation
detection
Some Radionuclides Measured with AMS
53Mn
60Fe
244Pu
236U
182Hf
210Bi
242Pu
239Pu
240Pu
63Ni
210Bi
241Pu
55Fe
© W. Kutschera
Applications of AMS to Astrophysics
GEOLOGICAL ISOTOPE ANOMALIES AS
SIGNATURES OF NEARBY SUPERNOVAE
Ellis, J., Fields, B.D., Schramm, D.N., 1996. ApJ 470, 1227.
B.D. Fields, 2004 New Astron. 48
Long-lived radionuclides (T1/2 ≈ Ma)
WHERE to look for:
Which isotopes:
• ice core
• sediments
• deep sea crusts
• 53Mn, 60Fe, 146Sm,
• 182Hf, 244Pu, 247Cm
•…
Live long-lived radionuclides on Earth
nearby supernova: < 100 pc, rate ~ 0.3 -10 (Ma)-1
(182Hf, 244Pu...)
(60Fe...)
Life 60Fe as Signature of Nearby Supernovae
• Deep-sea manganese crust (Pacific)
• Growth: 2.5 mm / Ma
• 28 layers (1-2 mm) were measured for 60Fecontent (T1/2=1.5 Ma)
• 60Fe: no significant terrestrial production
• GAMS-setup Munich (14-MV tandem)
Peak at 3 Ma!
Dating of crust via 10Be
60Fe:
T1/2 = 1.5 Ma
AMS at Munich
10Be:
T1/2 = 1.5 Ma
AMS at VERA
Applications of AMS to Astrophysics
1. Search for live radioisotopes as signatures of a nearby
supernovae
2. Recent nucleosynthesis
3. Solar system abundance
Applications of AMS to Astrophysics
1.
2.
3.
Search for live radioisotopes as signatures of a
nearby supernovae
Recent nucleosynthesis
Solar system abundance
2. + 3. Measurement of cross-sections at astrophysically interesting particle energies


10 – few 100 keV typical energies
depending on site, particle, element, ...
Applications of AMS to Astrophysics
•
•
•
Search for live radioisotopes as signatures of a nearby
supernovae
Recent nucleosynthesis
Solar system abundance
•
Nuclear reaction data - cross-section measurements
•
25Mg(p,
)26Al
•
54Fe(n,
)55Fe, 62Ni(n, )63Ni, 58Ni(n, )59Ni, 78Se(n,
•
40Ca(n,
)41Ca
•
10Be, 14C
)79Se,
production:
Nuclear Physics in the Sky
Recent nucleosynthesis: -ray astronomy (live radionuclides)
Comptel
(HEAO-3 telescope in 1982)
26Al
44Ti
Applications of AMS to Astrophysics
• Search for live radioisotopes as signatures of a nearby SN
• Recent nucleosynthesis: -rays from live radionuclides
• Solar system abundance:
Nuclear reaction data - cross-section measurements
)26Al
•
25Mg(p,
•
54Fe(n,
•
40Ca(n,
•
10Be, 14C
)55Fe, 62Ni(n, )63Ni, 58Ni(n, )59Ni, 78Se(n,
)79Se, ...
)41Ca
production: background studies at VERA
1.809 MeV -ray from decay of 26Alg
Map of the 1.809 MeV -ray line emission of
our galaxy traced by COMPTEL telescope
Origin of the 1.8 MeV γ-line
© R. Diehl
τ
Proton capture on 25Mg is the dominant production mechanism
25Mg(p,
γ)26Al
T1/2(26Al) = 700 000 yr << ~1010 yr of galactic evolution
nucleosynthesis is still active in the galaxy
Supernova
(1994D)
Massive stars (M ~
40 – 120 M) at
Wolf-Rayet phase
• 40 – 120 M
stars at W-R phase
• 4 – 9 M
stars at AGB phase
• 1 – 10 M
novae
• 10 – 25 M
Pre-Supernovae
• > 10 M
Supernovae
26Al
at VERA: 25Mg(p,)26Al
Resonance strength (eV)
-7
6x10
-7
5x10
197 keV resonance
-7
4x10
NACRE
-7
3x10
-7
2x10
9
VERA
(1.1 +- 0.3)
-7
1x10
0
2
4
2003
2004
9
2005
2006
NACRE
Measurement
2005
26Al/27Al
• (I)
(2.6  0.9)10-15 9 cts
• (II)
(2.5  0.8)10-15 9 cts
• (blank) (0.5  0.1)10-15 33 cts
•  = 4 – 5 10-4
(300 – 400 µg Al)
Applications of AMS to Astrophysics
• Recent nucleosynthesis:
• Solar system abundance: s-process nucleosynthesis
Nuclear reaction data - cross-section measurements
)26Al
•
25Mg(p,
•
54Fe(n,
•
40Ca(n,
•
10Be, 14C
)55Fe, 62Ni(n, )63Ni, 58Ni(n, )59Ni, 78Se(n,
)79Se, ...
)41Ca
production: background studies at VERA
62Ni(n,)63Ni
Bao & Kaeppeler (1987)
Bao et al. (2000)
– theoretical
35.5  4 mb
12.5  4 mb
Rauscher and Guber (2002) 40.3  5 mb
s-process path
62Ni
overproduction !
Applications of AMS to Astrophysics
• Recent nucleosynthesis:
• Solar system abundance: s-process nucleosynthesis
Nuclear reaction data - cross-section measurements
)26Al
•
25Mg(p,
•
54Fe(n,
•
40Ca(n,
•
10Be, 14C
)55Fe, 62Ni(n, )63Ni, 58Ni(n, )59Ni, 78Se(n,
)79Se, ...
)41Ca
production: background studies at VERA
See next talk by Peter Steier
Ca standard material
no background correction
41
41
40
measured Ca/ Ca ratio
(at/at)
Ca: standard measurements
• uncorrected (raw) ratios
• measured ratios
show a
Silsonfoils
good correlation with
P33n: 1600 nm
nominal ratios
P13n: 1000 nm
-11
10
-12
10
• detection eff.DLC: carbon
4 – foil
8%
-13
10
41Ca/40Ca:
-14
10
• blank  10-14 measured
-15
10
-15
10
-14
10
-13
-12
10
41
10
-11
10
-10
10
 10-13 nominell
40
nominal Ca/ Ca ratio (at/at)
1000 nm  340 µg/cm²
Ca measurement at VERA
41
st
(at/at)
Ca: sample 1 measurement
41Ca
-11
10
Standardmaterial
measured sample
40
measured Ca/ Ca ratio
-12
41
41K
TOF
10
-13
10
-14
10
-15
10
Blank & Standards
-15
10
Separation between 41K and 41Ca
-14
10
-13
-12
10
41
10
-11
10
-10
10
40
nominal Ca/ Ca ratio (at/at)
41Ca/40Ca
ratio: (1.52  0.10)  10-11
first direct measurement
Applications of AMS to Astrophysics
• Recent nucleosynthesis:
• Solar system abundance: s-process nucleosynthesis
Nuclear reaction data - cross-section measurements
)26Al
•
25Mg(p,
•
54Fe(n,
•
40Ca(n,
•
10Be, 14C
)55Fe, 62Ni(n, )63Ni, 58Ni(n, )59Ni, 78Se(n,
)79Se, ...
)41Ca
production: background studies at VERA
Applications of AMS to Astrophysics
4
He( n, )9 Be( ,n)12 C
4
He( n, )9 Be(n, )10 Be( , )14C
4
He(t ,  )7 Li(n, )8 Li( ,n)11B
• important for short time scale r-process
• neutron-rich Big Bang
•
9Be(n,
)10Be
very low cross sections i.e.
production rates
•
13C(n,
)14C
needs weeks of neutron irradiation
Background studies for BBN / high
neutron flux cases
results for the 13C enriched blank (graphite)
-15
• new samples: 110-16
• used samples 110-15
-15
2.5x10
Measurement series (n,g)_4: used samples
Measurement series (n,g)_4: new samples
-15
2.0x10
-15
1.5x10
-15
mean value: 1.3*10
used samples
•
14C
content low 
-15
1.0x10
-16
5.0x10
mean value: (1.0+- 0.5)*10
new samples
-16
Nota Bene:
0.0
Ag
_a
_o
ld
Cu
_a
_o
ld
Fe
_M
_o
ld
Fe
_a
_o
ld
C_
13
_g
_o
ld
Ag
_a
_n
ew
Fe
_M
_n
ew
Fe
_a
_n
ew
Fe
_b
_n
ew
14
13
C/ C isotope ratio (at/at)
3.0x10
High purity graphite:
14C/12C
< 10-17
Summary
© http://www.space-weltraum.de
http://antwrp.gsfc.nasa.gov/apod/image/earth_1_apollo17.gif
Cooperation:
•
VERA (Vienna):
A. Wallner, R. Golser, W. Kutschera, A. Priller, P. Steier
•
TRIUMF (Vancouver):
C. Vockenhuber
•
FZK (Karlsruhe):
I. Dillmann, F. Käppeler
•
GAMS (Munich):
T. Faestermann, K. Knie, G. Korschinek, G. Rugel
•
TANDAR (Buenos Aires):
A. Arazi, J.F. Niello
•
FZ Rossendorf (Dresden):
E. Richter
•
Racah Institute of Physics (Jerusalem):
M. Paul
Thank you for your attention !
VERA figure
55Fe
detection: Background studies
• similar case for 55Fe detection: isotope interference
55
Fe measurement with standard Fe powder
2,0
-14
HI-beamline incl. loss correction
(*10 )
1,8
1,6
55
1,4
54
Fe/ Fe upper limit
55
56
Fe/ Fe
1,2
1,0
0,8
55
56
upper limits Fe/ Fe
0,6
0,4
0,2
0,0
0
1
2
3
4
5
6
7
Fe sample
• results for standard Fe powder
• no enriched material
• only upper limits: 55Fe/56Fe < 10-16
54Fe
: 56Fe = 1 : 16
Ellis, J., Fields, B.D., Schramm, D.N., 1996. ApJ 470, 1227.
Basic features of some AMS-radionuclides – VERA
(3-MV)
Basic features of some AMS-radionuclides – VERA (3-MV)
Radionuclide
Half-life
(Myr)
Overall
Efficiency
Detection
Limit
Precision
10Be
1.5
5x10-5
<2x10-14
< 3%
14C
5730 yr
2x10-2
<3x10-16
< 0.5 %
26Al
0.7
1x10-4
<6x10-16
< 1.0 %
129I
15.7
1x10-2
2x10-14
2%
182Hf
8.9
1x10-4
1x10-11
5%
236U
23.4
--
6x10-11
5%
244Pu
80.0
>4x10-5
--
5%
Actinides, new: 41Ca, 54Fe, 36Cl:
Diehl
© Roland Diehl
at the
Munich 14-MV tandem
accelerator
AMS
Measurement
at Munich
26Al
26AlO-
12.5 MV
• AlO-
Al7+
with 100 MeV
• gas filled magnet: suppress Mg
26Al
at the VERA 3-MV tandem accelerator
26Al3+ (48%, 12 MeV)
• Al-
Al3+
with 12 MeV
• background level: 5  10-16
The stellar
25Mg(p,)26Al
reaction
See:
Poster Session II (Part 1)
(Thursday)
Stellar rates for the
25Mg(p,γ)26Al reaction
studied via AMS
A. Arazi, G. Korschinek et al.
Overview
•
•
•
•
•
•
•
•
•
AMS and nuclear astrophysics
Applications of AMS
Nuclear data activities
Key isotopes
Offline measurements
VERA (Vienna Environmental Research Accelerator) program
Other Labs
Parameters for some specific radionuclides
Applications
– 40Ca(n,γ)41Ca measurement at VERA
– Background measurements
Nuclear Astrophysics fingerprint
• Isotopic pattern
– Earth
– Solar system
– Meteorites
– Presolar grains
– IM
– ...
• Detection of extraterrestrial -ray lines
• blabla
Signature of a nearby SN
• Nearby SN explosion in the past confirmed
via
• detection of a radioisotope on Earth that was produced and
ejected by the SN
• well resolved time profile of 60Fe concentration in a deep-sea
ferromanganese crust
• highly significant increase 2.8 Myr ago.
• amount of 60Fe is compatible with the deposition of ejecta
from a SN at a distance of a few 10 pc.
Other SN-isotopes ?
•
244Pu
•
244Pu:
: C. Wallner et al. (2000): 1 count!
r-process nuclei !
• and other isotopes: 182Hf, 129l, 26Al, …
< SN-production + solar / terrestrial production
• project not finished: measurements are ongoing
Al measurements with AMS
• 14-MV tandem Munich: high currents using AlO• GAMS: suppress Mg (100 MeV, 7+)
• low background in region of interest
•
•
•
•
3-MV tandem (12 MeV, 3+) at VERA: Al–
Low background + high efficiency
VERA: background:  510-16
VERA: Overall efficiency obtained for 400 µg samples: 5104
• Samples: 26Al/27Al  1–210-15
Ca standard material
no background correction
41
41
40
measured Ca/ Ca ratio
(at/at)
Ca: standard measurements
-11
10
P33n: 1600 nm
P13n: 1000 nm
-12
10
Silsonfoils
-13
10
-14
DLC: carbon foil
10
-15
10
-15
10
-14
10
-13
10
41
-12
10
40
-11
10
nominal Ca/ Ca ratio (at/at)
DLC foil for channelplate
-10
10
• uncorrected ratios
• measured ratios show a
good correlation with
nominal ratios
• detection efficiency  1 %
• blank  10-15 measured
10-13 nominell
Ca measurement at VERA: sample
41Ca
41K
41Ca
41K
Discrimination between 41K and 41Ca
First measurement of irradiated sample for the
determination of the 40Ca(n,γ)41Ca cross section
at stellar temperatures
Inverse reaction: H(25Mg,)26Al
and recoil detection 26 3-6+
Al ( 25 -76
5. 26Mg separation
MeV)
and counting26Mg3
-6+
4. Reduction
of 26Mg
7,6 – 12,6 MV
3. Elimination
of 25Mg
2. Reaction
95 – 435 keV
CH4 Gas
stripper
25MgH-, 25MgO-, 25MgF 3
Summary
• AMS represents sensitive method for some long-lived
radionuclides
• Elaborate technique
• Wide range of applications (dating, biomedical, environmental, nuclear,
astrophysical, technological...)
• Offline measurement technique
• Long-lived nuclides: sensitive technique
• Astrophysical applications
– Quantify radionuclides from SN on Earth
– Long-lived radionuclides in meteorites, lunar rocks
– Cosmic ray studies
– Cross-section measurements
– T1/2 - measurements
– …
nuclear reaction data
(e.g. cross section)
Von wem?
nucleosynthesis
models
early solar
system
abundance
solar system abundance
of the elements
extinct radionuclides
isotopic anomalies
Mass Spectrometry
of stable isotopes
Radioactive Ion Beams
steady state
abundance
recent
nucleosynthesis
live radionuclides
-ray astronomy
-ray satellites
live radionuclides
on Earth
Accelerator Mass Spectrometry