ERNA: Measurement and R-Matrix analysis of 12 C( ) 16 O Daniel Schürmann University of Notre Dame Workshop on R-Matrix and Nuclear Reactions in Stellar

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




tandem accelerator



singlet

60° magnet

E-E telescope

recoil separation

doublet

analysing magnet

recoil focussing

Wien filter


Wien filter


triplet

side FC




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




tandem accelerator



singlet

60° magnet

E-E telescope

recoil separation

doublet

analysing magnet

recoil focussing

Wien filter


Wien filter


triplet

side FC




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




tandem accelerator



singlet

60° magnet

E-E telescope

recoil separation

doublet

analysing magnet

recoil focussing

Wien filter


Wien filter


triplet

side FC




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




tandem accelerator



singlet

60° magnet

E-E telescope

recoil separation

doublet

analysing magnet

recoil focussing

Wien filter


Wien filter


triplet

side FC




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!

Documents

ERNA: Measurement and R-Matrix analysis of 12 C( ) 16 O Daniel Schürmann University of Notre Dame Workshop on R-Matrix and Nuclear Reactions in Stellar