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ERNA: Measurement and R-Matrix analysis of 12C()16O
Daniel SchürmannUniversity of Notre Dame
Workshop on R-Matrix and Nuclear Reactions in Stellar Hydrogen and Helium BurningLa Fonda, Santa Fe, NM
April 21 – 23, 2008
1212C(C())1616OO„The holy grail of nuclear astrophysics“ (W. Fowler)„The holy grail of nuclear astrophysics“ (W. Fowler)
Cascades
E1,E2,E0 ?
6.05?
ERNA
- mea
sure
men
ts
Recoil Separator ERNA:an alternative approach to measure the reaction 12C()16O
Requirements• angular / energy acceptance• knowledge of charge state distribution• high purity of incoming 12C beam• suppression of 12C beam
ion source dynamitron
tandem accelerator
ion beam purification
Gastarget & Post-Stripper
singlet
60° magnet
E-E telescope
recoil separation
doublet
analysing magnet
recoil focussing
Wien filter
Wien filter Wien filter
Wien filter
magnetic quadrupole multiplets
triplet
side FC
Advantages•high efficiency ~pq
•measure tot•independent of ‘s•(mostly) background free•-ray coincidences possible
Nrecoils detected = Nprojectiles ntarget TERNA pq
Recoil Separator ERNA:an alternative approach to measure the reaction 12C()16O
Requirements• angular / energy acceptance• knowledge of charge state distribution• high purity of incoming 12C beam• suppression of 12C beam
ion source dynamitron
tandem accelerator
ion beam purification
Gastarget & Post-Stripper
singlet
60° magnet
E-E telescope
recoil separation
doublet
analysing magnet
recoil focussing
Wien filter
Wien filter Wien filter
Wien filter
magnetic quadrupole multiplets
triplet
side FC
Advantages•high efficiency ~pq
•measure tot•independent of ‘s•(mostly) background free•-ray coincidences possible
Nrecoils detected = Nprojectiles ntarget TERNA pq
Density Determination• Energy Loss (Stopping Power)• 7Li()11B• 7Li(´)7Li*
GastargetGastarget
Position [mm]-150 -100 -50 0 50 100 150
Aus
beut
e [a
.U.]
-510
-410
-310
-210
-110Messung upstream (d=2 mm)
Messung downstream (d=2 mm)
Messung ausserhalb (d=4 mm)
Integrand
Recoil Separator ERNA:an alternative approach to measure the reaction 12C()16O
Requirements• angular / energy acceptance• knowledge of charge state distribution• high purity of incoming 12C beam• suppression of 12C beam
ion source dynamitron
tandem accelerator
ion beam purification
Gastarget & Post-Stripper
singlet
60° magnet
E-E telescope
recoil separation
doublet
analysing magnet
recoil focussing
Wien filter
Wien filter Wien filter
Wien filter
magnetic quadrupole multiplets
triplet
side FC
Advantages•high efficiency ~pq
•measure tot•independent of ‘s•(mostly) background free•-ray coincidences possible
Nrecoils detected = Nprojectiles ntarget TERNA pq
Charge State DistributionCharge State Distribution
Charge State DistributionCharge State Distributionelectron losselectron loss
pressure p[mbar]0 1 2 3 4 5
prob
abili
ty
0
0.2
0.4
0.6
0.8
1
pressure p[mbar]0 1 2 3 4 5
prob
abili
ty
0
0.2
0.4
0.6
0.8
1
calculatedqrecoil = qcarbon
measured
qrecoil = qcarbon +2
12C3+ 16O6+
Ecm=3.2 MeV
pressure [mbar]
0 1 2 3 4 5
prob
abili
ty [%
]
0
10
20
30
40
50
60
70
80
90
100q=3+q=4+q=5+q=6+q=7+
16 3+ 4O 9.60 MeV in He
inte
grat
e
Solution:post-target stripper
Recoil Separator ERNA:an alternative approach to measure the reaction 12C()16O
Requirements• angular / energy acceptance• knowledge of charge state distribution• high purity of incoming 12C beam• suppression of 12C beam
ion source dynamitron
tandem accelerator
ion beam purification
Gastarget & Post-Stripper
singlet
60° magnet
E-E telescope
recoil separation
doublet
analysing magnet
recoil focussing
Wien filter
Wien filter Wien filter
Wien filter
magnetic quadrupole multiplets
triplet
side FC
Advantages•high efficiency ~pq
•measure tot•independent of ‘s•(mostly) background free•-ray coincidences possible
Nrecoils detected = Nprojectiles ntarget TERNA pq
AcceptanceAcceptance
Bad tuning
Good tuning
Matrix calculations:COSY INFINITY
These just give STARTING values:
Tune Separator with 16O pilot beam!
Angular acceptanceAngular acceptance
Ecm = 2.4 MeV qrec = 6+
Angular AcceptanceAngular Acceptance
[mrad]ϑ-40 -30 -20 -10 0 10 20 30 40
Tran
smis
sion
0
0.2
0.4
0.6
0.8
1
Bext. Triplet changed by 0.7% !
Energy AcceptanceEnergy Acceptance
-20 -15 -10 -5 0 5 10 15 200.0
0.2
0.4
0.6
0.8
1.0
trans
mis
sion
E / E0 [ % ] experimentalcalculated
by variation of beam energy
Recoil Separator ERNA:an alternative approach to measure the reaction 12C()16O
Requirements• angular / energy acceptance• knowledge of charge state distribution• high purity of incoming 12C beam• suppression of 12C beam
ion source dynamitron
tandem accelerator
ion beam purification
Gastarget & Post-Stripper
singlet
60° magnet
E-E telescope
recoil separation
doublet
analysing magnet
recoil focussing
Wien filter
Wien filter Wien filter
Wien filter
magnetic quadrupole multiplets
triplet
side FC
Advantages•high efficiency ~pq
•measure tot•independent of ‘s•(mostly) background free•-ray coincidences possible
Nrecoils detected = Nprojectiles ntarget TERNA pq
Typical E-E Spectra
Ecm = 2.2 MeVsuppression ~ 1·1011
Ecm = 4.4 MeVsuppression ~ 3·109
1212C(C())1616O total cross sectionO total cross section
[MeV]cmE2 2.5 3 3.5 4 4.5 5
[nb]
σ
-110
1
10
210
310
410
-1
+2+4 +4
+2
+0
Comparison ERNA <-> Calculation Kunz. et al. (Kunz R. et al., ApJ 567, 643-650 2002)
Basic resonance properties well reproducedClear need for improved (new) R-Matrix calculation
New R-Matrix codeNew R-Matrix code
rewritten from scratchrewritten from scratch utilizing classical formalism ORutilizing classical formalism OR
C. Brune’s alternative C. Brune’s alternative parameterizationparameterization
all relevant channels includedall relevant channels included-decay (-decay (1616N), (N), (), (), (,,)) [external (direct) [external (direct) capture]capture]
Acrobat-Dokument
[MeV]E0.5 1 1.5 2 2.5
N
1
10
210
310
410
510
16N decay
[MeV]cmE0.5 1 1.5 2 2.5 3
[keV
-bar
n]E
1S
1
10
210
E1 calcFey (Turntable)Fey (Eurogam)Kunzouellet
Fit to E1 groundstate data Assuncao et al.
Scattering data taken from:D’Agostino Bruno M. et al.,Nuovo Cimento A27, 1 (1975)
Plaga R. et al.,Nucl. Phys. A465, 291 (1987)
Calculation with parameters from:Tischhauser P. et al.,Phys. Rev. Lett. 88, 072501 (2002)
ResultsResults
(E)=S(E)·E-1 · e-2
•Compare to old R-Matrix calculation [Kunz et al., APJ 567, 643-650 (2002)]
•New data available: capture to Ex=6.05 MeV Level (DRAGON)
•No sign of „missing amplitude“
• total cross section data available in broad energy range fit needs improvements fit to total data should correlate different amplitudes
• Monte Carlo Error Estimate• Normalization (e.g. different E1 GS data sets)
Outlook
ERNA CollaborationERNA CollaborationBochumBochumA. Di LevaA. Di LevaR. KunzR. KunzD. RogallaD. RogallaC. RolfsC. RolfsF. SchümannF. SchümannD. SchürmannD. SchürmannF. StriederF. StriederH.-P. TrautvetterH.-P. Trautvetter
Naples & CasertaN. De CesareL. GialanellaA. D’OnofrioG. ImbrianiC. LubrittoA. OrdineV. RocaM. RomanoF. Terrasi
Thank you!