Coupled-channels calculations ofO16+O16fusion

Fusion data for 16 O+ 16 O are analyzed by coupled-channels calculations. It is shown that the calculated cross sections are sensitive to the couplings to the 2 + and 3 - excitation channels even at low energies, where these channels are closed. The sensitivity to the ion-ion potential is investigated by applying a conventional Woods-Saxon potential and the M3Y+repulsion potential, consisting of the M3Y double-folding potential and a repulsive term that simulates the effect of the nuclear incompressibility. The best overall fit to the data is obtained with a M3Y+repulsion potential that produces a shallow potential in the entrance channel. The stepwise increase in measured fusion cross sections at high energies is also consistent with such a shallow potential. The steps are correlated with overcoming the barriers for the angular momenta L = 12, 14, 16, and 18. To improve the fit to the low-energy data requires a shallower potential and this causes a even stronger hindrance of fusion at low energies. It is therefore difficult, based on the existing fusion data, to make an accurate extrapolation to energies that are of interest to astrophysics.

[1]  G. Milburn,et al.  Beyond the coherent coupled channels description of nuclear fusion. , 2007, Physical review letters.

[2]  A. Chieffi,et al.  Implications of low-energy fusion hindrance on stellar burning and nucleosynthesis , 2007 .

[3]  K. Hagino,et al.  Existence of a one-body barrier revealed in deep subbarrier fusion , 2007, 0704.2825.

[4]  H. Esbensen,et al.  Signature of shallow potentials in deep sub-barrier fusion reactions , 2007, nucl-th/0702054.

[5]  B. Back,et al.  Expectations for {sup 12}C and {sup 16}O induced fusion cross sections at energies of astrophysical interest , 2007 .

[6]  B. Back,et al.  First evidence of fusion hindrance for a small Q-value system , 2006 .

[7]  T. L. Belyaeva,et al.  New γ-ray measurements forC12+C12sub-Coulomb fusion: Toward data unification , 2006 .

[8]  H. Esbensen,et al.  Hindrance of heavy-ion fusion due to nuclear incompressibility. , 2006, Physical review letters.

[9]  B. Back,et al.  Systematics of heavy-ion fusion hindrance at extreme sub-barrier energies , 2005, nucl-ex/0508001.

[10]  K. Hagino,et al.  Systematics of precise nuclear fusion cross sections: the need for a new dynamical treatment of fusion? , 2004 .

[11]  H. Esbensen.  Coupled-channels Calculations of Heavy-ion Fusion Reactions , 2004 .

[12]  G. Pollarolo,et al.  Investigating the nucleus-nucleus potential at very short distances , 2003 .

[13]  B. Back,et al.  Unexpected behavior of heavy-ion fusion cross sections at extreme sub-barrier energies. , 2002, Physical review letters.

[14]  W. Myers,et al.  Nuclear equation of state , 1998 .

[15]  A. Balantekin,et al.  Quantum tunneling in nuclear fusion , 1997, nucl-th/9708036.

[16]  C. Vries,et al.  Nuclear charge-density-distribution parameters from elastic electron scattering , 1987 .

[17]  Thomas,et al.  Sub-barrier fusion of the oxygen isotopes: A more complete picture. , 1986, Physical review. C, Nuclear physics.

[18]  C. Barnes,et al.  Fusion and elastic scattering cross sections for the ^(16)O+ ^(16)O reactions near the Coulomb barrier , 1984 .

[19]  P. Hodgson.  Heavy ion reactions , 1982 .

[20]  C. Rolfs,et al.  Comparison of the fusion reactions12C+20Ne and16O+16O near the Coulomb barrier , 1980 .

[21]  A. Gavron,et al.  Total fusion cross section for the /sup 16/O + /sup 16/O system , 1978 .

[22]  R. Broglia.  Heavy ion reactions , 1978, Nature.

[23]  B. Heusch,et al.  Reaction cross sections forC12+C12 , 1977 .

[24]  U. Mosel,et al.  Self-consistent heavy-ion potentials , 1976 .

[25]  K. Knöpfle,et al.  Evidence for the isoscalar giant quadrupole resonance in $sup 16$O , 1975 .

[26]  H. Spinka,et al.  Experimental determination of the total reaction cross section of the stellar nuclear reaction 16O + 16O☆ , 1974 .

[27]  R. Wieland,et al.  Entrance Channel Phenomena in Complex Nuclear Scattering , 1973 .

[28]  B. Nagorcka,et al.  Experimental investigation of 16O + 12C nuclear burning at stellar energies , 1971 .