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The O-14(alpha, p)F-17 reaction is one of the key reactions involved in the breakout from the hot-CNO cycle to the rp-process in type-I x-ray bursts (XRBs). The resonant properties in the compound nucleus Ne-18 have been investigated through resonant elastic scattering of F-17 + p. The radioactive F-17 beam was separated by the Center for Nuclear Study radioactive ion beam separator (CRIB) and bombarded a thick H-2 gas target at 3.6 MeV/nucleon. The recoiling light particles were measured by three Delta E-E silicon telescopes at laboratory angles of theta(lab) approximate to 3 degrees, 10 degrees, and 18 degrees. Five resonances at E-x = 6.15, 6.28, 6.35, 6.85, and 7.05 MeV were observed in the excitation functions, and their spin-parities have been determined based on an R-matrix analysis. In particular, J(pi) = 1(-) was firmly assigned to the 6.15-MeV state which dominates the thermonuclear O-14(alpha, p)F-17 rate below 2 GK. As well, a possible new excited state in Ne-18 was observed at E-x = 6.85 +/- 0.11 MeV with tentative J = 0 assignment. This state could be the analog state of the 6.880 MeV (0(-)) level in the mirror nucleus O-18, or a bandhead state (0(+)) of the six-particle four-hole (6p-4h) band. A new thermonuclear O-14(alpha, p)F-17 rate has been determined, and the astrophysical impact of multiple recent rates has been examined using an XRB model. Contrary to previous expectations, we find only a modest impact on predicted nuclear energy generation rates from using reaction rates differing by up to several orders of magnitude.

Two reactions of 14O(α,p)17F and 18Ne(α,p)21Na provide the pathways for breakout from the hot CNO cycles to the rp-process in type I X-ray bursts. To better determine their astrophysical reaction rates, resonance parameters of the compound nuclei 18Ne and 22Mg have been investigated by the resonant elastic scattering of 17F+p and 21Na+p, respectively. The 17F and 21Na radioactive ion beams were produced at the CNS Radioactive Ion Beam Separator and impinged on the thick proton targets. The excitation functions were obtained with a thick-target method over a wide excitation energy range. The resonance parameters in the compound nuclei 18Ne and 22Mg have been determined through an R-matrix analysis. New reaction rates of these two (α,p) reactions are recalculated. The astrophysical impact for the 18Ne(α,p)21Na reaction has been investigated through one-zone postprocessing X-ray burst calculations.

The 18Ne(alpha, p)Na-21 reaction provides a pathway for breakout from the hot CNO cycles to the rp process in type-l x-ray bursts. To better determine this astrophysical reaction rate, the resonance parameters of the compound nucleus Mg-22 have been investigated by measuring the resonant elastic scattering of Na-21 + p. An 89 MeV Na-21 radioactive ion beam was produced at the CNS Radioactive Ion Beam Separator and bombarded an 8.8 mg/cm(2) thick polyethylene target. The recoiled protons were measured at scattering angles of theta(c.m.) approximate to 175 degrees and 152 degrees by three Delta E-E silicon telescopes. The excitation function was obtained with a thick-target method over energies Ex (Mg-22) = 5.5-9.2 MeV. The resonance parameters have been determined through an R-matrix analysis. For the first time, the J(pi) values for ten states above the a threshold in Mg-22 have been experimentally determined in a single consistent measurement. We have made three new J(pi) assignments and confirmed seven of the ten tentative assignments in the previous work. The Ne-18(alpha, p)Na-21 reaction rate has been recalculated, and the astrophysical impact of our new rate has been investigated through one-zone postprocessing x-ray burst calculations. We find that the Ne-18(alpha, p)Na-21 rate significantly affects the peak nuclear energy generation rate and the onset temperature of this breakout reaction in these phenomena.

The elastic scattering of ${}^{8}$B by a ${}^{\mathrm{nat}}$Pb target was measured at an incident energy of 170.3 MeV. Special care was taken with the limited intensity and broad profile of the secondary beam. The measured angular distribution of the differential cross section shows that the Coulomb-nuclear interference peak (CNIP) is not suppressed in this system, in contrast to what was observed in the scattering of neutron halo nuclei by heavy targets at energies around the Coulomb barrier. Analyses of the angular distribution were performed both in terms of the optical model using a single-folding-type potential and the continuum discretized coupled-channels (CDCC) method, which explicitly takes into account the breakup-channel couplings to the elastic scattering. The overall pattern of the differential cross section is well reproduced by the CDCC calculations. The calculations show that the effect of breakup-channel couplings on the elastic scattering is small in the present case.

Astrophysical 18Ne(α,p)21Na reaction is one of the most probable breakout routes, which lead to the rp-process from the hot-CNO cycle, converting the initial CNO elements into heavier elements in Type I x-ray bursters. Presently, there is no much experimental cross-section data reported at the energy of astrophysical interest, and resonant spectroscopic information in compound 22Mg is scarce as well. The experiment has been carried out by using the CNS radioactive ion beam separator (CRIB). Resonant properties in 22Mg have been studied via the resonant elastic scattering of 21Na+p, and cross section of the time-reversal reaction of 21Na(p,α)18Ne been measured simultaneously. A wide excitation energy region up to Ex ∼ 9.5 MeV in 22Mg has been scanned with a thick-target method. Some preliminary results will be reported.

Resonant properties in 18Ne relevant to the stellar reaction of 14O(α,p)17F have been investigated through a resonant elastic scattering of 17F+p. The 17F RI beam was produced via a projectile-fragmentation reaction, and subsequently separated and purified by a Radioactive Ion beam Line in Lanzhou (RIBLL). After a series of energy degradation, a 4.21 AMeV 17F beam bombarded a thick (CH2)n target at T2 terminal. Energy and angle of the recoiled protons were measured by two sets of ΔE-E silicon telescope at θlab ≈ 0°, 14° respectively. Several resonances in 18Ne were observed, and their resonant parameters including energy, spin-parity and decay width have been determined by an R-Matrix analysis of the experimental excitation function.

Angular distributions for the elastic scattering of 7Be and 8B by an enriched 208Pb target were measured at the Radioactive Ion Beam Line at Lanzhou (RIBLL). The incident energies of the radioactive beams were about three times the respective Coulomb barriers. A suppressed Coulomb-nuclear Interference Peak (CNIP) is not observed for 8B, a pronounced proton halo nucleus. Optical model fits were performed using Woods-Saxon potentials and the total reaction cross sections deduced. The results are discussed.