Youbao Wang

Current progress of nuclear astrophysics study and BRNBF at CIAE

Abstract A secondary beam line (GIRAFFE) at the Beijing tandem accelerator lab was constructed for yielding low energy secondary beams. The current progress on the study of nuclear astrophysics and nuclear structure is presented. Up to now, we have carried out measurement of 7 Be(d,n) 8 B, 11 C(d,n) 12 N, 8 Li(d,n) 9 Be and 6 He(p,n) 6 Li reactions. The proposed Beijing radioactive nuclear beam facility and its current R&D progress are briefly introduced. This facility is based on the exist HI-13 tandem accelerator. A proton cyclotron will be built to provide 100 MeV 200 μA proton beam, together with an isotope separator on line system and a super-conducting heavy ion LINAC. By this facility, intensity of order of 10 9 pps radioactive nuclear beams for mass up to A =120 will be produced.

Measurement of the Angular distribution for the 7Be(d, n)8B reaction and determination of the astrophysical S factor for the 7Be(p, γ)8B reaction

Abstract The differential cross section for the 7Be(d, n)8B reaction at Ec.m.=5.8 MeV has been measured using a 7Be beam produced by the radioactive nuclear beam facility at the China Institute of Atomic Energy. The 8B ions were detected in full geometry with a two dimensional position sensitive ΔE-E counter telescope. The reaction cross section was determined to be 58±8 mb. The angular distribution data were analyzed with a distorted-wave Born approximation calculation. The astrophysical S17(0) factor for the 7Be(p, γ)8B reaction was derived to be 27.4±4.4 eV b through the asymptotic normalization constant extracted from the experimental data.

INDIRECT MEASUREMENTS OF NUCLEAR ASTROPHYSICS REACTIONS USING UNSTABLE NUCLEAR BEAMS

This paper described the nuclear astrophysical studies using the unstable ion beam facility GIRAFFE, by indirect measurements. We measured the angular distributions for some single proton or neutron transfer reactions, such as 7Be(d,n)8B, 11C(d,n)12N, 8Li(d,n)9Be, 8Li(d,p)9Li and 13N(d,n)14O in inverse kinematics, and derived the astrophysical S-factors or reaction rates of 7Be(p,γ)8B, 11C(p,γ)12N, 8Li(n,γ)9Li, 13N(p,γ)14O by asymptotic normalization coefficient, spectroscopic factor, and R-matrix approach at astrophysically relevant energies.

Experimental studies on the primordial lithium abundance

Lithium isotopes have attracted an intense interest because the abundances of both 6Li and 7Li from big bang nucleosynthesis (BBN) are the puzzles in nuclear astrophysics. Many investigations of astrophysical observation and BBN calculations have been carried out in order to solve the puzzles. Several nuclear reactions involving lithium have been determined at HI-13 tandem accelerator, Beijing, China. The BBN model calculations are then performed to investigate the primordial Lithium abundance. The result shows that these nuclear reactions have minimal effect on the primordial abundances of 6Li and 7Li.

Indirect Measurement of Astrophysical13C(α, n)16OS-Factors

The 13C(α, n)16O reaction is believed to be the main neutron source reaction for the s-process in asymptotic giant branch (AGB) stars. The astrophysical S-factors of this reaction have been determined based on an evaluation of the α spectroscopic factor of the 1/2+ subthreshold state in 17O (Ex = 6.356 MeV) by using the 13C(11B, 7Li)17O α transfer reaction. Our result confirms that the 1/2+ subthreshold resonance is dominant for the 13C(α, n)16O reaction at low energies of astrophysical interest.

Current progress of nuclear astrophysics experiments at CIAE

This paper described current progress of nuclear astrophysical studies using the unstable ion beam facility GIRAFFE. We measured the angular distributions for some low energy reactions, such as 11C(d,n)12N, 8Li(d,p)9Li and 17F(d,n)18Ne in inverse kinematics, and indirectly derived the astrophysical S‐factors or reaction rates of 11C(p,γ)12N, 8Li(n,γ)9Li, 8B(p,γ)9C at astrophysically relevant energies.

Indirect measurements of nuclear astrophysics reactions at CIAE

This paper described the nuclear astrophysical studies using the unstable ion beam facility GIRAFFE, by indirect measurements. We measured the angular distributions for some single proton or neutron transfer reactions, such as 7Be(d,n)8B, 11C(d,n)12N, 8Li(d,n)9Be, 8Li(d,p)9Li and 13N(d,n)14O in inverse kinematics, and derived the astrophysical S‐factors or reaction rates of 7Be(p,γ)8B, 11C(p,γ)12N, 8Li(n,γ)9Li, 13N(p,γ)14O by asymptotic normalization coefficient, spectroscopic factor, and R‐matrix approach at astrophysically relevant energies.