Transcript Potential of AMS for Quantifying Long

Experimental Nuclear Astrophysics with
Accelerator Mass Spectrometry
Anton WALLNER
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 (isobar suppression)
• 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
• …(TOF, gas-filled magnet, 14
deltaTOF) …
Not only
C-dating
What is AMS ?
Mass spectrometric method
• Sample material into an ion source: (neg./pos. beam)
• 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
81Kr
79Se
59Ni
39Ar
32Si
63Ni
44Ti
239Pu
240Pu
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, & 2005
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 (SN II): < 100 pc, rate ~ 0.3 -10 (Ma)-1
(182Hf, 244Pu...)
(60Fe...)
Knie
Life 60Fe as Signature of Nearby
Supernovae
AMS Measureme
• Deep-sea manganese crust
• 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: 2.5 - 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, 40Ca(, )44Ti
•
54Fe(n,
)55Fe, 62Ni(n, )63Ni, 58Ni(n, )59Ni, 78Se(n,
•
40Ca(n,
)41Ca
•
10Be, 14C,
)79Se,
...
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, 40Ca(, )44Ti
•
25Mg(p,
•
54Fe(n,
•
40Ca(n,
•
10Be, 14C,
)55Fe, 62Ni(n, )63Ni, 58Ni(n, )59Ni, 78Se(n,
)79Se, ...
)41Ca
...
1.809 MeV -ray from decay of 26Alg
Map of the 1.809 MeV -ray line emission of
our galaxy traced by COMPTEL telescope
– TANDAR, Buenos Aires.
– MLL, TU Munich
– FZ Rossendorf
– VERA, Vienna
Proton capture on 25Mg is the dominant production mechanism
Astrophysical production of 26Al
26Si
The 25Mg(p,) reaction is the main production
mechanism of 26Al in the H-burning Mg-Al chain.
27Si

(p, )
28Si

(p, )
(p, )
Possible scenarios for its production:
1. Explosive H-burning at
 O-Ne enriched novae
 Core collapse supernovae
2. Hydrostatic H-burning at
 Massive stars at Wolf-Rayet phase (W-R)
 Asymptotic Giant Branch stars (AGB)
Temp.
Eproton
25Al
26Alm
27Al
26Alg
200 MK 200 keV
(p, )

(p, )
60 MK
100 keV
 7.105y
(p, )
6,4s
24Mg
25Mg
26Mg
A spatial correlation observed between 26Al rays and massive-star-produced microwave
emission suggests that the later scenario should account for the major 26Al production[3].
•
•
•
•
Measurements
all with
of prompt
γ-radiation
The reaction rateexists;
is a clue to discern
betweendetection
these possible sources.
The present work
aims to an experimental determination of the production rates for both scenarios.
Irradiation of 25Mg-samples with p
Add 27Al and convert to Al2O3 for AMS
Offline measurement of the produced 26gAl via AMS
26Al
at MLL/VERA: 25Mg(p,)26Al
Resonance strength (eV)
-7
Resonance strength (eV)
0.12
0.10
GAMS results
VERA results
NACRE evaluation
0.08
0.06
0.04
0.02
300
320
340
360
380
400
420
440
6x10
-7
5x10
197 keV resonance
-7
4x10
NACRE
-7
3x10
-7
2x10
(1.1 +- 0.3)
-7
1x10
0
2
4
2003
2004
Resonance energy (keV)
2005
26Al/27Al
9
2005
2006
NACRE
Measurement
• (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
9
VERA
(300 – 400 µg Al)
preliminary
See:
Arazi et al. 2006
Applications of AMS to Astrophysics
• Recent nucleosynthesis:
• Solar system abundance: s-process nucleosynthesis
Nuclear reaction data - cross-section measurements
•
25Mg(p,
•
54Fe(n,
•
40Ca(n,
)26Al
)55Fe, 62Ni(n, )63Ni, 58Ni(n, )59Ni, 78Se(n,
)79Se, ...
)41Ca
10Be, 14C, ...
•• neutron
irradiation with 25 keV
• Maxwellian spectrum (FZK)
• offline measurement via AMS
62Ni(n,)63Ni
– theoretical
Bao & Kaeppeler (1987)
35.5  4 mb
Bao et al. (2000)
12.5  4 mb
Rauscher and Guber (2002) 40.3  5 mb
s-process path
62Ni
overproduction !
FZK +AMS – Argonne: Nassar +
2005
Tokyo: prompt - -rays: Tomyo +
2005
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
studies at VERA
 Silicon nitride foils
 new technique
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 results from VERA
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
studies at VERA
Basic features of some AMS-radionuclides – VERA
(3-MV)
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
VERA figure
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
<<
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
Applications of AMS to Astrophysics
4
He( n, )9 Be( ,n)12C
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 sensitive method
Ellis, J., Fields, B.D., Schramm, D.N., 1996. ApJ 470, 1227.
)13N radiative capture reaction
12C(p,
El ciclo C-N
13C
(p, )
1H(12C,
14N
)13N
(p, )
(e+n)
13N
+ 1H  13N + 
12C-
15O
(p, )
12C-
(e+n)
stripper gas H2
12C
15N
(p, )
13N3+ + 13C3+
A Study of the Tandem-TerminalStripper Reaction 1H(12C,)13N with AMS
J. Niello et al. NIM B (2005) in press
See: M. Paul, D. Fink, G. Hollos, NIM B29 1987
Resonance strength (eV)
10
End66
Nei74
Elix79
And80
Kei80
Cha83
End86
-1
10
-2
10
-6
10
-7
10
-8
10
-9
End87
Cha89
Rol90
Ili90
NACRE
Pow98
AMS
417.7 keV
373.9 keV
303.8 keV
10
92.1 keV
189.4 keV
-10
50
100
150
200
250
300
350
Resonance C.M. energy (keV)
400
450