Nuclear astrophysics measurements with DRAGON
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Nuclear astrophysics measurements with DRAGON Jennifer Fallis
Published online: 23 October 2013 © Springer Science+Business Media Dordrecht 2013
Abstract The DRAGON facility in ISAC-I at TRIUMF was designed to measure radiative capture reactions of importance for astrophysics in inverse kinematics. This work will provide a short summary of experiments to date, outline the status of the separator and its detectors, as well as discuss recent developments. Keywords Recoil mass separator · Radiative capture · Nucleosynthesis · Novae · Supernovae
1 Introduction DRAGON, the Detector of Recoils And Gammas Of Nuclear reactions, located in the medium energy area of the ISAC facility at TRIUMF, has been designed with the specific purpose of measuring radiative capture reactions, predominantly reactions of astrophysical importance. The range of beam energies that can be delivered by ISAC-I, in combination with the availability of both stable and radioactive beams, allows for measurements of reactions of interest in a large variety of different astrophysical environments. Astrophysically motivated studies to date have included measurements of importance to: –
production of isotopic observables in nova, such as the contribution of 21 Na( p, γ )22 Mg to the production of 22 Na (γ -ray astronomy) [1, 2], 26g Al( p, γ )27 Si to the destruction of 26g Al (γ -ray astronomy) [3], 33 S( p, γ )34 Cl
ISAC and ARIEL: The TRIUMF Radioactive Beam Facilities and the Scientific Program. J. Fallis (B) TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3, Canada e-mail: [email protected]
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to the production of 34 Cl (γ -ray astronomy) and destruction of 33 S (presolar grains) [4, 5], as well as 17 O( p, γ )18 F [6] and 18 F( p, γ )19 Ne [7] to determine the abundance of 18 F (γ -ray astronomy), important nucleosynthesis pathways in novae such as a measurement of 23 Mg( p, γ )24 Al which is an important link between the Ne-Na and Mg-Al cycles [8], stellar He burning through the investigation of both 12 C(α, γ )16 O [9], and 16 O(α, γ )20 Ne [10, 11], to study the production and destruction of 16 O, 44 Ti production in core-collapse supernova explosions via 40 Ca(α, γ )44 Ti [12], s-process abundances in massive stars by measuring 17 O(α, γ )21 Ne which is potentially a significant neutron poison [13], and stellar and big bang nucleosynthesis through the study of the 3 He(α, γ )7 Be reaction at higher energies [14].
Additionally, non-astrophysically motivated reactions, such as 16 O(12 C,γ )28 Si to explore the 12 C−16 O cluster structure in 28 Si [15], have been studied.
2 Experimental Reactions at DRAGON are studied in inverse kinematics to take advantage of the radioactive beams delivered by ISAC, nearly all of which are too short-lived to ever be used as a target for measurements in regular kinematics. As astrophysical reactions of interest typically involve the capture of protons and alpha particles, a windowless gas target is used. Gas targets have certain advantages: they are uniform, free of impurity layers,
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