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The 20Ne(p, γ)21Na reaction is the starting point of the NeNa cycle, which is an important process for the production of intermediate mass elements. The Ec.m. = 1113 keV resonance plays an important role in the determination of stellar rates for this reaction since it is used to normalize experimental direct capture yields at lower energies. The commonly accepted strength of this resonance, ωγ = 1.13 ± 0.07 eV, has been misinterpreted as the strength in the center-of-mass frame when it is actually the strength in the laboratory frame. This has motivated a new measurement of the Ec.m. = 1113 keV resonance strength in 20Ne(p, γ)21Na using the DRAGON recoil mass spectrometer. The DRAGON result, 0.972 ± 0.11 eV, is in good agreement with the accepted value when both are calculated in the same frame of reference. [ABSTRACT FROM AUTHOR]

Complete γ-decay in the 12C(12C,γ)24Mg and 12C(16O,γ)28Si reactions has been measured at energies close to the Coulomb Barrier using the DRAGON spectrometer and its associated BGO γ-array at the TRIUMF facility. The experimental data show an important feeding of doorway states around 10-11 MeV in both reactions. Comparisons with simulations allow to extract the full capture cross section and the main spin involved in the process. Different models are confronted to the results : completely statistical, semi-statistical with an unique entrance spin and cluster. The resolution of the BGO enables to eliminate a fully statistical scenario but is not enough to disentangle the two remaining scenarii. It is shown that the future PARIS array composed of the recently developed LaBr3 scintillators will have capabilities to distinguish between these two scenarii. [ABSTRACT FROM AUTHOR]

This paper discusses how the radiative capture process can shed light on the origin of the resonances observed in light heavy-ion collisions. The impact of resonant features on the fusion cross-sections is described from energies around the Coulomb barrier down to the Gamow energy in systems like 12C+12C and 12C+16O. [ABSTRACT FROM AUTHOR]

Abstract: The DRAGON facility at TRIUMF/ISAC detects reaction products following radiative capture of a hydrogen or helium target nucleus by an accelerated heavy ion. Capture reactions of interest in nuclear astrophysics may have reaction rates 10–14 orders of magnitude lower than the intensity of the incident beam: as well as efficiently transporting the heavy reaction product from the target to a suitable particle detector, the separator must provide most of the suppression of unreacted beam. We describe the features of beam background encountered in a range of proton- and alpha-capture experiments at the DRAGON facility. [Copyright &y& Elsevier]

Abstract: We present new measurements of the charge-state distribution (CSD) of a 1.068MeV/u C beam in He and of the 6+:5+ charge-state population ratio in the recoils of the 12C(α,γ)16O reaction, both measured at the DRAGON recoil mass spectrometer. A computer simulation to model the CSD of both beam and recoil particles in inverse-kinematics experiments is compared to data from this work and from previous work at ERNA. The simulation provides good agreement with both data sets. The results suggest that, for this fusion reaction on the J π =4+ resonance at E beam =1.064MeV/u, immediately after fusion, the recoil ions contain only the nucleons and not the electrons of the target He atom. [Copyright &y& Elsevier]

Abstract: The performance of the DRAGON recoil spectrometer at TRIUMF-ISAC has been studied using radiative capture reactions with stable beams of 12C, 20Ne, 21Ne, 23Na, 24Mg and 26Mg. Calibration of the deflection magnet measuring the beam energy was established and the beam suppression factors of the separator were investigated. Yields from six narrow resonances were measured and compared with previous results. For the 1,112.6keV resonance in our result is in disagreement with the NACRE database assignment but agrees with another previous result. [Copyright &y& Elsevier]

The heavy-ion radiative capture 12C(O16,γ28Si) was measured at the sub-Coulomb barrier bombarding energy Elab = 15.7 MeV, which corresponds to the lowest important resonance observed in the 12C+ O16 fusion excitation function. Thanks to combination of the bismuth germanate (BGO) γ-ray array and the 0° DRAGON electromagnetic spectrometer at TRIUMF, the γ-decay spectrum from the entrance channel down to the ground state of 28Si was measured. Comparisons of the experimental spectrum to γ spectrum extracted from Monte Carlo simulations of the complete setup suggest a Jπ = 2+ spin-parity assignment to the entrance channel and yield the radiative capture cross section ωRC = 0.22±0.04μb. Combining this present spin assignment with previous data on radiative capture, a J(J+1) systematics was constructed, and it indicated a moment of inertia commensurate with the 12C+O16 grazing angular momentum. Strong dipole transitions are observed from the entrance channel to T=1 states around 11.5 MeV and are found to result from enhanced M1IV transitions to states exhausting a large part of the M1 sum rule built on the ground state of 28Si. This specific decay was also reported at bombarding energies close to the Coulomb barrier in our previous study of the 12C(12C,γ24Mg) heavy-ion radiative capture reaction. Similarities between both systems are investigated. [ABSTRACT FROM AUTHOR]

The heavy-ion radiative capture reaction 12C(16O,γ)28Si has been studied at three energies Ec.m. = 8.5, 8.8, and 9 MeV which are close to the Coulomb barrier. The weak radiative capture process has been identified by measuring the 28Si recoils in the highly selective 0° spectrometer DRAGON at TRIUMF (Vancouver). The coincident γ rays have been recorded in the associated BGO array. This has allowed a complete measurement of the γ spectrum and the relative strength of all decay pathways. An important part of the decay through quasibound states close to the particle threshold and the feeding of bound states with particular deformation have been identified for the first time. Comparisons with Monte Carlo simulations allowed the extraction of the full experimental radiative capture cross section. Our results suggest an important contribution of spins Jπ = 5- and 6+ in the entrance channel. The surprisingly large cross sections from 12 μb at Ecm = 8.5 MeV to 25 μb at Ec.m.= 9.0 MeV for the heavy-ion radiative capture process are discussed in terms of the interplay between statistical and structural aspects of the process. [ABSTRACT FROM AUTHOR]