Measurement of 23Na(α,p)26Mg at energies relevant
to 26Al production in massive stars and
nucleosynthesis in SNIa
Jessica Tomlinson
jrt501@york.ac.uk
Overview
n
★ Astrophysical mo>va>on: ★ 26Al produc>on in massive stars ★ Nucleosynthesis in SNA Ia
★ Previous experimental measurements and results
★ Experimental setup for measurement with the TUDA scaLering chamber ★ Analysis and Results
Measurement ofn23Na(α,p)26Mg with TUDA
Jessica Tomlinson
26Al in Astrophysics
n
26Al
decays to 26Mg emitting a gamma ray with the energy 1.8 MeV.
Observations show that the most likely production site is in massive stars
and three stages of evolution have been suggested:
Pre-supernova in the C/Ne convective shell
Ne/C burning during core collapse
Core H burning for stars M≥ 30 M⊙
The focus of this work is the production of 26Al in the C/Ne convective
shell.
Diagram from Illiadis et al. 2011
Measurement ofn23Na(α,p)26Mg with TUDA
COMPTEL collaboration
Jessica Tomlinson
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Onion structure before collapse
Diagram from Illiadis et al. 2011
Typical temperature of the C burning shell does not allow substantial production of 26Al.
However strong contraction and heating of core induces strong temperature increase in C burning shell.
If there is an efficient convective shell at this point then 26Al can be produced.
Measurement ofn23Na(α,p)26Mg with TUDA
Jessica Tomlinson
23Na(α,p)26Mg and 26Al produc>on
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Illiadis et al. (2011) carried out detailed calculations and found that 6 reactions have large effects on the
amount of 26Al produced in in the C/Ne convective shell. The fourth most important is23Na(α,p)26Mg.
26Al
27Al
24Mg 25
Mg 26Mg
23Na
22Ne
26Al
is produced via the reaction 25Mg(p,γ)26Al.
Second most important proton generating reaction after 12C(12C,p)23Na is the 23Na(α,p)26Mg reaction.
23Na(α,p)26Mg with TUDA
Measurement of n
Jessica Tomlinson
Nucleosynthesis in type Ia
supernovae
n
Important in the chemical evolution of the galaxy.
Can observe the chemical composition in optical and infra red
spectrum for days after the explosion and x-ray spectrum for
hundreds of years.
Also a target for γ-ray astronomy as they produce radioactive
isotopes.
Sensitivity study by Bravo and Martinez-Pinedo found that with
factor of 10 increase in 23Na(α,p)26Mg:
14
21
23
29
32
33
37
40
45
N, Ne, Na, Si, P, S, Cl, Ca, Sc,
increase of between 0.12 and 2
26
44
Ti,
47
Ti showed
43
Mg, Ca show at least factor of 2 increase.
E. Bravo and G. Maŕınez-Pinedo, Phys. Rev. C 85, 055805 (2012) n
6
n
Previous measurements
Both carried out measurements in normal
kinematics with a 4He beam and a NaCl target.
Both suffered problems with the target being
unstable leading to large uncertainties.
Measurement ofn23Na(α,p)26Mg with TUDA
Jessica Tomlinson
n
Argonne Experiment
They found that the reac>on rate was a factor of 40 higher than the sta>s>cal model rates. This is significant as a factor of 10 increase in reac>on rate results in a factor of 3 increase in abundance of 26Al.
Measurement ofn23Na(α,p)26Mg with TUDA
Jessica Tomlinson
8
Our measurement
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We made measurements at 18
energies during 3 sets of beam time
3600
1560 - 3150
2900
1800
+ 4He
8270 keV
23Na
10090 keV
1280 - 1430
26Mg
+p
27Al
Q value =1.82 MeV
not to scale
Measurement ofn23Na(α,p)26Mg with TUDA
Jessica Tomlinson
Our measurement
n
Measurement was made in the Gamow window for
Neon/Carbon convective shell burning:
T~1.25GK, EG=1.2 - 2.2 MeV
We made measurements at 18
energies during 3 sets of beam time
3600
1300 - 3800
ΔEG 2
1560 - 3150
1800
1280 - 1430
+ 4He
8270 keV
23Na
10090 keV
1200 - 2200
ΔEG 1
2900
27Al
Measurement was made in the Gamow window for
nucleosynthesis in type 1a supernovae:
T~2-4 GK, EG=1.3 - 3.8 MeV
Measurement ofn23Na(α,p)26Mg with TUDA
26Mg
+p
Q value =1.82 MeV
not to scale
Jessica Tomlinson
Experiment was carried out at TRIUMF in Vancouver
TUDA
Experimental setup
n
LEDA single sided
silicon detector
DE-E silicon telescope
Gas Cell
23Na
4He
beam
4 cm
Au
2 cm
Monitor detector.
Measurementn
of 23Na(α,p)26Mg with TUDA
Gas cell has 2.5um Ni
Entrance window, 6um
Ni exit window.
Target is 110 Torr 4He
DE-E telescope covers
θlab~ 10o - 30o.
Each S2 has 48 annular
front strips and 16
radial back sectors.
Jessica Tomlinson
ΔE - E and gas cell
LEDA
Gas Cell
Using DE-E to identify particles
n
LEDA
23Na
Au foil
DE-E
10.0
Gas Cell
Energy in DE (MeV)
9.0
Gas in
8.0
αs from 23Na(p,α)
7.0
6.0
5.0
4.0
3.0
Protons from
23Na(p,p)23Na
reaction on entrance
window
Protons from
23Na(α,p)26Mg
2.0
protons from fusion
evaporation of 23Na on
16O and 12C
1.0
1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0
Energy in E (MeV)
Measurement ofn23Na(α,p)26Mg with TUDA
Jessica Tomlinson 14
Background Subtraction
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Counts/100 keV
Protons from
23Na(p,p)23Na
reaction on entrance
window
Protons from
23Na(α,p )26Mg
0
Gas in target
Gas out
300
250
200
150
100
50
0
0
2
Protons from
23Na(α,p )26Mg
2
Measurement ofn23Na(α,p)26Mg with TUDA
4
6
8
10
12
14
Energy (MeV)
Protons from fusion
evaporation of 23Na on
16O and 12C on
entrance window
Jessica Tomlinson
15
Background Subtraction
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300
Ecm = 1.66 - 1.79 MeV
Background subtracted
Simulation
200
p0
100
0
b)
Ecm = 2.34 - 2.48 MeV
200
p2
p0
100
0
0
2
4
6
8
10
Energy (MeV)
12
Counts/100 keV
800
0
14
2
4
6
8
10
12
14
Energy (MeV)
p1
Ecm = 2.97 - 3.09 MeV
600
p3 p2
400
p0
200
0
Measurement of 23Na(α,p)26Mg with TUDA
0
2
n code written by Prof. Alex Murphy
Monte Carlo - modified
Counts/100 keV
Counts/100 keV
p1
p1
300
4
6
8
Energy (MeV)
10
12
14
Jessica Tomlinson
16
Results
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100
10
σ (mb)
Cross section (mb)
1
0.1
This work σtot
This work σp2
This work σp1
This work σp0
Non-Smoker σptot
0.01
0.001
1e-04
2
3
EEnergy(MeV)
cm (MeV)
Non-Smoker - T. Rauscher and F.-K. Thielemann, At. Data Nucl. Data Tables 75, 1 (2000)
n
17
Results
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10 3
10 2
10 1
σ (mb)
σ (mb)
10 0
10 -1
Almaraz-Calderon et al. σtot
Almaraz-Calderon et al. σp0
This work σtot
This work σp0
Non-Smoker σptot
SMARAGD σptot
SMARAGD σp0
10 -2
10 -3
10 -4
10 -5
1.5
2.0
2.5
3.0
Ecm (MeV)
Non-Smoker - T. Rauscher and F.-K. Thielemann, At. Data Nucl. Data Tables 75, 1 (2000)
n
SMARAGD - T. Rauscher,
Int. J. Mod. Phys. E, 20, 1071 (2011)
S. Almaraz-Calderon et al., Phys. Rev. Lett. 112, 152701 (2014) 18
Reaction Rates
<σv> (cm3s-1mole-1)
Y-Title
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10
3
10
2
10
1
10
0
10
-1
10
-2
10
-3
1.0
This work
This work upper and lower limits
Non-Smoker
1.5
2.0
2.5
Temperature (GK)
X-Title
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Non-Smoker rate taken from JINA REACLIB
19
Ratios to Non-Smoker rate
Ratio to Non-Smoker rate
Y-Title
n
1.5
This work
This work upper and lower limits
Non-Smoker
1.0
0.5
1.5
n
2.0
Temperature
(GK)
X-Title
2.5
20
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Conclusions
★The cross sec>ons are much lower than those reported by Almaraz-­‐Calderon et al. ★At temperatures relevant for 26Al produc>on in C/Ne convec>ve burning shell have limits on the reac>on rate are 0.4 -­‐ 1.3 >mes the Non-­‐Smoker rate used by Iliadis et al. ★
The effect of the 23Na(α,p)26Mg reac>on rate uncertainty on the amount of 26Al produced in the Ne/C convec>ve burning shell can be constrained to conserva>ve limits of 0.71 and 1.3 >mes the amount produced with the Non-­‐Smoker rate. ★
More experimental data is now needed to reduce the uncertainty on the other rates
Measurement ofn23Na(α,p)26Mg with TUDA
Jessica Tomlinson
21
n
University of York, UK A.M. Laird, S.P. Fox, B.R. Fulton, M. A. Bentley University of Edinburgh, UK T. Davinson, A. St. J. Murphy, A. C. ShoHer TRIUMF, Canada J. Fallis, C. Akers, G. ChrisKan, B. Davids, N. Galinski, C. Ruiz, A. Rojas M. Shen IPN Orsay, France N. de Sereville Measurement n
of 23Na(α,p)26Mg with TUDA
Jessica Tomlinson