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Nuclear Astrophysics Measurements with Radioactive Ion Beams
Oak Ridge National Lab.
We are using high-quality, intense beams of radioactive nuclei from the Holifield Radioactive Ion Beam Facility (HRIBF) to make precision measurements of crucial nuclear reactions which occur in stellar explosions such as novae and X-ray bursts. These explosions serve to synthesize heavy elements from light elements, generate enormous energies, and are responsible for the evolution of cataclysmic binary star systems. Accelerated radioactive nuclear beams are required for these studies because the extremely high temperatures and densities in stellar explosions lead to the synthesis of, and subsequent nuclear reactions with, radioactive isotopes. Direct measurements of these reactions with HRIBF beams provide an opportunity to advance our understanding of stellar element synthesis and stellar evolution.
These measurements are being carried out with a Silicon Detector Array (SIDAR), and we will soon begin measurements using the Daresbury Recoil Separator, a 90-ton, 13-meter mass separator coupled to a number of sophisticated detector systems. We are incorporating our nuclear physics measurements into state-of-the-art computer stellar models to help interpret the new generation of astrophysical observations (e.g., from the Hubble Space Telescope and Compton Gamma Ray Observatory) and to guide both future stellar observations and future nuclear measurements.
More details of our program are given in an articles describing our recent accomplishments and a program overview. The astrophysical implications of one of our measurements is described in this press release prepared for the American Astronomical Society. The utilization of radioactive ion beams for nuclear astrophysics studies is discussed in detail in the review article "Nuclear Astrophysics Measurements with Radioactive Beams", M.S. Smith & K.E. Rehm, Ann. Rev. Nucl. Part. Sci. 51, 91 (2001).
Recent Measurements
We have measured the following reactions at HRIBF to better understand stellar explosions such as novae, X-ray bursts, and supernovae:
* 17F(p,p)17F to determine the 17F(p,gamma)18Ne reaction rate
D.W. Bardayan et al., Phys. Rev. C62 (2000) 055804 Abstract Article
D.W. Bardayan et al., Phys. Rev. Lett. 83 (1999) 45 Abstract Article
Physical Review Focus Article, July 1999 Article
* 17F(p,alpha)14O, 17F(p,p)17F, and 17F(p,p')17F to determine the 14O(alpha,p)17F reaction rate
J.C. Blackmon et al., in preparation (2003)
J.C. Blackmon et al., Nucl. Phys. A718 (2003) 127 Abstract Article
J.C. Blackmon et al., Nucl. Phys. A688 (2001) 142 Abstract Article
R. Brummitt et al., Bull. American Phys. Soc. (2001) Abstract
* 18F(p,p)18F to determine the 18F(p,gamma)19Ne and 18F(p,alpha)15O reaction rates
D.W. Bardayan et al., in preparation (2003)
D.W. Bardayan et al., Phys. Rev. C62 (2000) 042802(R) Abstract Article
* 18F(p,alpha)15O to determine this reaction rate directly
D.W. Bardayan et al., Phys. Rev. Lett. 89 (2002) 262501 Abstract Article
D.W. Bardayan et al., Nucl. Phys. A718 (2003) 590 Abstract Article
D.W. Bardayan et al., Phys. Rev. C63 (2001) 065802 Abstract Article
D.W. Bardayan et al., Nucl. Phys. A688 (2001) 475 Abstract Article
* 28Si(p,t)26Si to determine the 25Al(p,gamma)26Si reaction rate
D.W. Bardayan et al., Nuc. Phys. A718 (2003) 505 Abstract Article
D.W. Bardayan et al., Phys. Rev. C65 (2002) 032801 Abstract Article
* 18F(d,p)19F to determine the 18F(p,gamma)19Ne and 18F(p,alpha)15O reaction rates
R.L. Kozub et al., in preparation (2003)
R.L Kozub et al., Bull. American Phys. Soc. (2003) Abstract
* 124Sn(d,p)125Sn to determine the 124Sn(n,gamma)125Sn reaction rate
R.L. Kozub et al., in preparation (2003)
* 17F(14N,13C)18Ne* to determine the direct capture 17F(p,gamma)18Ne reaction rate
J.C. Blackmon et al., in preparation (2003)
J.C. Blackmon et al., Nucl. Phys. A718 (2003) 587 Abstract Article
* 82Ge(d,p)83Ge to determine the level structure of 83Ge and the 82Ge(n,gamma)83Ge reaction rate
J.L. Thomas et al., in preparation (2003)
J.L. Thomas et al.,Bull. American Phys. Soc. (2003) Abstract
Planned Experiments
A number of nuclear astrophysics experiments with radioactive ion beams have been approved or are planned for the near future:
* 17F(p,gamma)18Ne
* 7Be(p,gamma)8B
* 7Be(p,p)7Be
* 18F(p,alpha)15O
* 132Sn(d,p)133Sn
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Nuclear Astrophysics Measurements