institute for structure and nuclear astrophysics nuclear science laboratory e381: search of...
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Institute for Structure and Nuclear AstrophysicsNuclear Science Laboratory
E381: Search of potential resonances in the 12C+12C fusion reaction using charged-
particle decays from the 24Mg(,’)24Mg* reaction
X. Tang( 唐暁東 ), G. P. Berg, T. Kawabata, B. Bucher, F. Xiao, D. Patel, R. Talwar, A. Long, N. Yokota, U. Garg, M. Wiescher, Y.-W. Lui, K. Hatanaka, A. Tamii, Y. Fujita, E. Ganioglu, G.
Susoy, B. Bilgier, H.C. Kozer, M. Freer
University of Notre Dame, USAUniversity of Kyoto, Japan
Texas A&M University, USAOsaka University, Japan
Istanbul University, TurkeyUniversity of Birmingham, UK
Institute for Structure and Nuclear AstrophysicsNuclear Science Laboratory
Outline
• Why do we need resonance information from indirect measurement?
• Is it possible to get resonance information from 24Mg(,’)?
• How to select the 24Mg states relevant to the 12C+12C fusion reaction?
• Rate estimation.
Institute for Structure and Nuclear AstrophysicsNuclear Science Laboratory
•Detect Fusion Residues •Detect light charged particles•Detect gamma rays
Ex(24Mg)~Ecm(12C+12C)+14 MeV
Institute for Structure and Nuclear AstrophysicsNuclear Science LaboratoryCarbon burning in the
universeThe extrapolation to low energy is uncertain … and more experimental and theoretical studies are urgently needed.
Fowler, Nobel Lecture (1983)
NSAC Long Range Plan 2007
Institute for Structure and Nuclear AstrophysicsNuclear Science Laboratory
Challenge for Laboratory nuclear-Astrophysics in Underground and Surface 2009: CLAUS2009
R. Cooper et al., APJ (2009) 702, 660Gasques et al. PRC 72 (2005) 025806Jiang et al. PRC 75 (2007) 015803
? ?Hindrance?
Large uncertainties in 12C+12C
Institute for Structure and Nuclear AstrophysicsNuclear Science Laboratory
1.E+15
1.E+16
1.E+17
1.E+18
1.E+19
1.E+20
1 2 3 4 5 6 7
Ec.m. (MeV)
S*
(Me
V*b
)
No-coupling Limit Coupling Limit
resonance 1 resonance 2
this work Becker
Patterson Aguilera
Spillane
The proposed resonances at Ecm=1.5 MeV (Ex=15.5 MeV)
T. Spillane et al., Strong resonance at 2.14 MeV with width <12keV; PRL98 (2007) 122501; dismissed by a recent experiment at Naples. R. Cooper et al., APJ (2009) 702, 660
Institute for Structure and Nuclear AstrophysicsNuclear Science Laboratory
24Mg(a,a’) inelasticSearch
the poss
ible
resonance
s
Direct measurement
The exact cross section
12C+13C13C+13C
Provide potential to
model the smooth
behavior
12C+13C13C+13C
Provide potential to
model the smooth
behavior
12C+13C13C+13C 12C+12C
12C(12C,n)23Mg
12C(12C,p)23Na
12C(12C,a)20Ne
12C(12C,8Be)16O
12C(12C,a)20Ne
Institute for Structure and Nuclear AstrophysicsNuclear Science Laboratory
Notre Dame-ANL-IU carbon fusion experiment
A 5 MV Pelletron with ECR source in terminal. Will be installed at the end of 2011.
Clover array at ANLGeorgina at ND
Institute for Structure and Nuclear AstrophysicsNuclear Science Laboratory
1.0E-20
1.0E-18
1.0E-16
1.0E-14
1.0E-12
1.0E-10
1.0E-08
1.0E-06
1.0E-04
1.0E-02
1.0E+00
0.00 1.00 2.00 3.00 4.00 5.00
Ecm (MeV)
xs
ec
(b
)
Cooper(res1)
Cooper(res2)
ND_estimation
Naples : 10 puA beam; 1.5% eff.; proton channel only ; 0.5 evt/days;ND-ANL-IU: >40 puA beam; 45% eff.; both proton and alpha; 4*30*2 evt/days;
If add particle + gamma coincidence: 240*8% evt/days
Institute for Structure and Nuclear AstrophysicsNuclear Science Laboratory
Impact of the potential resonances to astrophysical reaction rate
0.00
1.00
2.00
3.00
4.00
5.00
6.00
0.00 0.50 1.00 1.50 2.00
Temperature (x1E9 K)
Re
ac
tio
n R
ate
Ra
tio Er=1.5 MeV,G=0.1MeV
Er=1.6 MeV,G=0.1 MeV
Er=1.5 MeV,G=0.05MeV
Carbon core burning
Carbon shell burning
Explosive Carbon burning
Super-burst
Institute for Structure and Nuclear AstrophysicsNuclear Science Laboratory
16O
12C12C
12C+ 12C cluster components in 24Mg (g.s.)
Therefore, the 12C+12C resonant states could be strongly populated by the 24Mg(,’)!
AMD+GCM calculation by Y. Kanada-Enyo
Institute for Structure and Nuclear AstrophysicsNuclear Science Laboratory
(a)
4+
2+2+
2+0+
4+/2+
Ex (MeV)
Arb
itra
ry u
nit
4+
2+2+
2+0+
4+/2+
Ex (MeV)
co
un
ts
(b)
Identified 0+
2+ statescoincide with 12C+12C
??
2+
3-
4+
RCNP:+0.18 MeV; KVI:+0.10 MeV
PreliminarySpectrum at 0 degfrom E308
KVI
Institute for Structure and Nuclear AstrophysicsNuclear Science Laboratory
Grand Raiden at RCNP, Osaka UniversityPrecise energy calibration (<20 keV) confirm the correlationExcellent energy resolution (<50 keV) Resolving statesMeasurement of angular distribution Check spin assignment
Institute for Structure and Nuclear AstrophysicsNuclear Science Laboratory
1.E-16
1.E-12
1.E-08
1.E-04
1.E+00
1.E+04
1.E+08
0.00 2.00 4.00 6.00 8.00
Ecm (MeV)
reso
nan
ce s
tren
gth
(eV
)
Predition
Exp
The predicted nuclear structure for the candidate states (14MeV<Ex<17 MeV)
• J should be 0+/2+.
• Decay mainly by p, or 8Be
• 12C decay branching ratio (BR):BR<1E-5 (Ecm<3 MeV)
BR~10% (Ecm=6 MeV)
Institute for Structure and Nuclear AstrophysicsNuclear Science Laboratory
Decay spectroscopy:
•p, and 8Be
•Probe nuclear structure
•Enhance spin selection
Goal: Try to find the signature for the 12C+12C states at Ecm> 3MeV(Ex>17 MeV) and then apply it to the states with Ecm<3 MeV (Ex<17MeV).
PreliminaryData from E308
The p/ decay spectroscopy has been studied at 0 deg by E308.
We will perform the decay measurement at the angle where the 2+ reach its maximum.
Institute for Structure and Nuclear AstrophysicsNuclear Science Laboratory
The 12C(12C,8Be)16O channel
Institute for Structure and Nuclear AstrophysicsNuclear Science Laboratory
8Be decay dominates?
24Mg(a,a’+8Be): new way to investigate the clustering state
Institute for Structure and Nuclear AstrophysicsNuclear Science Laboratory
Decay detector setup
Decay eff: 3.6% (p and a) 0.9% (8Be)
Institute for Structure and Nuclear AstrophysicsNuclear Science Laboratory
5mb/sr; 20% background; 10 enA 388 MeV beam;
2 mg/cm^2Rate: 3.8x104 cnt/hrGR dispersion matching set up to get resolution < 50 keV (x 3 days)
Energy calibration ( 400 MeV x 1% = 40 MeV, 3 magnetic field setting) determine resonance energy with uncertianty < 20 keV (3 hr)Angular calibration (8 hr)Angular distribution (0, 2.5, 3.7, 5, 6, 7.4, 8.8, 10.2, and 11.6 (9 angles) (24 hours)
Decay measurement (4 days)Thin target: 0.2 mg/cm2
Decay eff: 3.6% (p and ) 0.9% (8Be) p/a: ~3000 cnt/day (12000 cnt/4 days)8Be:~3000 cnt/4 days12C/16O contamination: 1 day
Total: 3 days+12 hours+1day+4 days+1 day~9 days + 12 hours
Institute for Structure and Nuclear AstrophysicsNuclear Science Laboratory
Budget
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