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Abstract: The DRAGON facility for the study of radiative capture reactions has an extended gas target, surrounded by an array of BGO detectors. The distribution of detected gamma rays amongst the segmented array permits an estimate of the reaction position and consequently of the resonance energy. We report a study of the technique, using the 24Mg(p, )25Al reaction. Energy determination to better than 0.5% has been demonstrated. [Copyright &y& Elsevier]

Resonant scattering studies were performed using radioactive 20,21Na beams at ISAC between energies of 0.5 keV/u and 1.5 keV/u. Intensities of up to 1 × 108 /sec were used with thick CH2 targets, and elastic and inelastic proton resonances were observed corresponding to states in 21,22Mg by detecting recoil protons using the LEDA silicon array. A multichannel R-Matrix formalism was used to fit the excitation functions leading to the deduction of partial widths and spin-parity assignments. In certain cases definite spin-parity assignments could be made without fitting angular distributions due to the constraining nature of Coulomb-interfering resonances. Where possible, analogue assignments are made in the A=22, T=1, system based on the 21Na+p analysis. [Copyright &y& Elsevier]

A DT neutron yield diagnostic based on the reactions, 63Cu(n,2n)62Cu(β+) and 65Cu(n,2n) 64 Cu(β+), has been fielded at the National Ignition Facility (NIF). The induced copper activity is measured using a NaI γ-γ coincidence system. Uncertainties in the 14-MeV DT yield measurements are on the order of 7% to 8%. In addition to measuring yield, the ratio of activities induced in two, well-separated copper samples are used to measure the relative anisotropy of the fuel ρR to uncertainties as low as 5%. [ABSTRACT FROM AUTHOR]

In Wolf-Rayet and asymptotic giant branch (AGB) stars, the 26gAl(p,γ)27 Si reaction is expected to govern the destruction of the cosmic γ-ray emitting nucleus 26Al. The rate of this reaction, however, is highly uncertain due to the unknown properties of key resonances in the temperature regime of hydrogen burning. We present a high-resolution inverse kinematic study of the 26gAl(d,p)27Si reaction as a method for constraining the strengths of key astrophysical resonances in the 26gAl(p,γ)27Si reaction. In particular, the results indicate that the resonance at Er = 127keV in determines the entire 26gAl(p,γ)27Si reaction rate over almost the complete temperature range of Wolf-Rayet stars and AGB stars. [ABSTRACT FROM AUTHOR]

We report here a determination of the asymptotic normalization coefficient of the valence neutron in 8Li from a measurement of the angular distribution of the 7Li(8Li,7Li)8Li reaction at 11 MeV. Using isospin symmetry the 8B ANC has also been calculated and used to infer a value for S17(0) of 20.2 ± 4.4 eV b. [ABSTRACT FROM AUTHOR]

In stars, 16O represents the endpoint of the helium burning sequence due to the low rate of 16O(α,γ)20Ne. We present a new direct measurement of the total cross section of 16O(α,γ)20Ne at Ec.m. = 1.69 MeV employing the DRAGON recoil separator. In addition, the branching ratios and strength of the Ec.m. = 2.426 MeV 3- resonance were determined. [ABSTRACT FROM AUTHOR]

The 18Ne(α,p)21Na reaction provides one of the main HCNO-breakout routes into the rp process in x-ray bursts. The 18Ne(α,p0)21Na reaction cross section has been determined for the first time in the Gamow energy region for peak temperatures 7 ∼ 2 GK by measuring its time-reversal reaction 21Ne(p,α)18Ne in inverse kinematics. The astrophysical rate for ground-state to ground-state transitions was found to be a factor of 2 lower than Hauser-Feshbach theoretical predictions. Our reduced rate will affect the physical conditions under which breakout from the HCNO cycles occurs via the 18Ne(p,α)21Na reaction. [ABSTRACT FROM AUTHOR]

The 17O(p,γ)18F reaction plays an important role in hydrogen-burning nucleosynthesis. Conflicting values for the low-energy behavior of its cross section exist in the literature. We present direct measurements of the astrophysical S factor of the 17O(p,γ)18F reaction at center-of-mass energies between 250 and 500 keV. These measurements were conducted in inverse kinematics at the DRAGON recoil separator. [ABSTRACT FROM AUTHOR]

Abstract: The Nuclear Astrophysics program at TRIUMF, particular the one centered around the DRAGON and TUDA facilities, as well as some additional experiments will be discussed. In particular, measurements of the 12C(α,γ)16O, the 26Al(p,γ)27Si and the 40Ca(α,γ)44Ti reactions at DRAGON will be described. For the TUDA facility a measurement of 10B(α,p)13C as a test for the 18Ne(α,p)21Na measurement is presented. The development of the new cylindrical, large solid angle gas detector TACTIC will be described. In addition, new measurements refuting a temperature dependence of radioactive decay times in metals will be presented as well as GEANT4 simulations regarding the β-delayed α-spectrum of 16N will be given. [Copyright &y& Elsevier]

Abstract: Nuclear reactions play a key role in understanding nucleosynthesis in stars. Recoil mass spectrometers such as DRAGON are well suited to study reactions with respect to astrophysical production because of direct detection of reaction products. Here we present the first stage of an experiment running at the recoil mass spectrometer DRAGON at the ISAC/TRIUMF facility in Vancouver, Canada, to study the reaction 40Ca(α,γ)44Ti at astrophysically relevant energies. This reaction is one of the key reactions for production of 44Ti, which has been identified in young supernova remnants by space based γ-ray telescopes onboard COMPTEL and INTEGRAL. In this paper we focus on technical upgrade of DRAGON for 40Ca(α,γ)44Ti and preliminary results at resonances at E x ∼9.2MeV. [Copyright &y& Elsevier]

Abstract: Preliminary studies in preparation for an absolute cross-section measurement of the radiative capture reaction 3He()7Be with the DRAGON recoil separator have demonstrated beam suppression at the 90% confidence level. A measurement of this cross section by observation of 7Be recoils at the focal plane of the separator should be virtually background free. [Copyright &y& Elsevier]

This Letter reports a study of the highly debated 10Li structure through the d(9Li, p)10Li one-neutron transfer reaction at 100 MeV. The 10Li energy spectrum is measured up to 4.6 MeV and angular distributions corresponding to different excitation energy regions are reported for the first time. The comparison between data and theoretical predictions, including pairing correlation effects, shows the existence of a p1/2 resonance at 0.45 ± 0.03 MeV excitation energy, while no evidence for a significant s-wave contribution close to the threshold energy is observed. Moreover, two high-lying structures are populated at 1.5 and 2.9 MeV. The corresponding angular distributions suggest a significant s1/2 partial-wave contribution for the 1.5 MeV structure and a mixing of configurations at higher energy, with the d5/2 partial-wave contributing the most to the cross section. [ABSTRACT FROM AUTHOR]