Institute for Structure and Nuclear Astrophysics Nuclear Science Laboratory E381: Search of potential resonances in the 12 C+ 12 C fusion reaction using charged- particle decays from the 24 Mg( ,  ’) 24 Mg* 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, USA University of Kyoto, Japan Texas A&M University, USA Osaka University, Japan Istanbul University, Turkey University of Birmingham, UK

Institute for Structure and Nuclear Astrophysics Nuclear Science Laboratory Outline Why do we need resonance information from indirect measurement? Is it possible to get resonance information from 24 Mg( ,  ’)? How to select the 24 Mg states relevant to the 12 C+ 12 C fusion reaction? Rate estimation.

Institute for Structure and Nuclear Astrophysics Nuclear Science Laboratory Detect Fusion Residues Detect light charged particles Detect gamma rays E x ( 24 Mg)~E cm ( 12 C+ 12 C)+14 MeV

Institute for Structure and Nuclear Astrophysics Nuclear Science Laboratory Carbon burning in the universe The 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 Astrophysics Nuclear Science Laboratory Challenge for Laboratory nuclear-Astrophysics in Underground and Surface 2009: CLAUS2009 R. Cooper et al., APJ (2009) 702, 660 Gasques et al. PRC 72 (2005) Jiang et al. PRC 75 (2007) ? ? Hindrance? Large uncertainties in 12 C+ 12 C

Institute for Structure and Nuclear Astrophysics Nuclear Science Laboratory The proposed resonances at E cm =1.5 MeV (E x =15.5 MeV) T. Spillane et al., Strong resonance at 2.14 MeV with width <12keV; PRL98 (2007) ; dismissed by a recent experiment at Naples. R. Cooper et al., APJ (2009) 702, 660

Institute for Structure and Nuclear Astrophysics Nuclear Science Laboratory 24 Mg(a,a’) inelastic Search the possible resonances Direct measurement The exact cross section 12 C+ 13 C 13 C+ 13 C Provide potential to model the smooth behavior 12 C+ 13 C 13 C+ 13 C Provide potential to model the smooth behavior 12 C+ 13 C 13 C+ 13 C 12 C+ 12 C 12 C( 12 C,n) 23 Mg 12 C( 12 C,p) 23 Na 12 C( 12 C,a) 20 Ne 12 C( 12 C, 8 Be) 16 O 12 C( 12 C,a) 20 Ne

Institute for Structure and Nuclear Astrophysics Nuclear 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 Clover array at ANL Georgina at ND

Institute for Structure and Nuclear Astrophysics Nuclear Science Laboratory 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 Astrophysics Nuclear Science Laboratory Impact of the potential resonances to astrophysical reaction rate Carbon core burning Carbon shell burning Explosive Carbon burning Super-burst

Institute for Structure and Nuclear Astrophysics Nuclear Science Laboratory 16O   12C 12 C+ 12 C cluster components in 24 Mg (g.s.) Therefore, the 12 C+ 12 C resonant states could be strongly populated by the 24 Mg( ,  ’)! AMD+GCM calculation by Y. Kanada-Enyo

Institute for Structure and Nuclear Astrophysics Nuclear Science Laboratory (a) /2+ E x (MeV) Arbitrary unit /2+ E x (MeV) counts (b) Identified states coincide with 12C+12C ?? RCNP:+0.18 MeV; KVI:+0.10 MeV Preliminary Spectrum at 0 deg from E308 KVI

Institute for Structure and Nuclear Astrophysics Nuclear Science Laboratory Grand Raiden at RCNP, Osaka University Precise energy calibration (<20 keV)  confirm the correlation Excellent energy resolution (<50 keV)  Resolving states Measurement of angular distribution  Check spin assignment

Institute for Structure and Nuclear Astrophysics Nuclear Science Laboratory The predicted nuclear structure for the candidate states (14MeV<E x <17 MeV) J  should be 0 + /2 +. Decay mainly by p,  or 8 Be 12 C decay branching ratio (BR): BR<1E-5 (Ecm<3 MeV) BR~10% (Ecm=6 MeV)

Institute for Structure and Nuclear Astrophysics Nuclear Science Laboratory Decay spectroscopy: p,  and 8 Be 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). Preliminary Data 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 Astrophysics Nuclear Science Laboratory The 12 C( 12 C, 8 Be) 16 O channel

Institute for Structure and Nuclear Astrophysics Nuclear Science Laboratory 8 Be decay dominates? 24Mg(a,a’+8Be): new way to investigate the clustering state

Institute for Structure and Nuclear Astrophysics Nuclear Science Laboratory Decay detector setup Decay eff: 3.6% (p and a) 0.9% (8Be)

Institute for Structure and Nuclear Astrophysics Nuclear Science Laboratory 5mb/sr; 20% background; 10 enA 388 MeV  beam; 2 mg/cm^2 Rate: 3.8x10 4 cnt/hr GR 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/cm 2 Decay eff: 3.6% (p and  ) 0.9% ( 8 Be) p/a: ~3000 cnt/day (12000 cnt/4 days) 8Be:~3000 cnt/4 days 12C/16O contamination: 1 day Total: 3 days+12 hours+1day+4 days+1 day~9 days + 12 hours

Institute for Structure and Nuclear Astrophysics Nuclear Science Laboratory Budget