Don Hunter

Nuclear astrophysics at ISAC with DRAGON: Initial studies

Abstract The new DRAGON recoil separator facility, designed and built to measure directly the rates of radiative proton and alpha capture reactions important for nuclear astrophysics, is now in operation at the TRIUMF-ISAC radioactive beams facility in Vancouver, Canada. Experiments have been conducted for the first time on the 21 Na(p,γ) 22 Mg reaction. The evolution of nova explosions, and particularly their 22 Na abundance, depends sensitively on this reaction rate. Commissioning studies using the well-known stable beam reactions 21 Ne(p,γ) 22 Na, 20 Ne(p,γ) 21 Na, and 24 Mg(p,γ) 25 Al have shown that the recoil separator performs within its design specifications both in suppression power and acceptance. The first radioactive beam studies were done using a beam of 5 × 10 8 21 Na atoms/s. Yield measurements recording simultaneously singles and coincident heavy-ion and gamma signals were performed, scanning in energy over the known resonance reported previously in 22 Mg at E cm = 212 keV, and in addition, over a strong resonance observed at E cm ≈822 keV.

Testing the ISAC radioactive ion accelerator beam specifications using the H(15N,αγ)12C reaction

Important ion beam parameters like energy spread and stability of the new isotope separator and accelerator accelerator at TRIUMF were determined during the first beamtime with the detector of recoils and gammas of nuclear gas target and BGO array. For this purpose a variation of the nuclear resonance method, using a geometrical scan over the resonance as placed in an extended gas target cell, as well as time-of-flight correlations were employed.

Nuclear astrophysics studiesat dragon: The 21Na(p,γ)22Mg reaction and oxygen-neon novae

Abstract The rate of the 21 Na(p,γ) 22 Mg reaction is expected to play a major role in the nucleosynthesis of 22 Na in Oxygen-Neon novae, leading to the emission of a characteristic 1.28 MeV gamma-line. This paper reports on preliminary results of the first direct measurements of this reaction and its astrophysical implications.

Nuclear Astrophysics at ISAC with DRAGON: Initial Studies

The new DRAGON recoil separator facility, designed and built to measure directly the rates of radiative proton and alpha capture reactions important for nuclear astrophysics, is now in operation at the TRIUMF‐ISAC radioactive beams facility in Vancouver, Canada. Experiments have been conducted for the first time on the 21Na(p,γ)22Mg reaction. The evolution of nova explosions, and particularly their 22Na abundance, depends sensitively on this reaction rate. The radioactive 21Na beam with an intensity of up to 5 × 108 /s was directed onto a windowless hydrogen gas target (3.8 × 1018 H atoms/cm2). Prompt reaction gamma rays were detected using a BGO array and separated reaction products detected using a silicon strip detector at the end of the 20.8 m recoil mass separator. Yield measurements recording simultaneously singles and coincident signals were performed by scanning in energy over the known resonance reported previously in 22Mg at Ecm = 212 keV, and in addition, over a strong resonance observed at Ecm...