Document The Third European Summer School on Experimental Nuclear Astrophysics
M. Busso, R.G. Pizzone, C. Rolfs, C. Spitaleri and A. Tumino (eds)
EAS Publications Series, 27 (2007) 171-183
DOI: 10.1051/eas:2007152
Indirect Methods in Nuclear Astrophysics: ANCs
R.E. TribbleCyclotron Institute, Texas A&M University, College Station, Texas 77843, USA
(Published online: 27 September 2007)
Abstract
Our understanding of stellar evolution depends on knowing beta-decay rates and reaction cross
sections for a wide range of nuclear capture reactions. Direct laboratory measurements of
important stellar reaction rates are hindered by low cross sections and, in some cases, the need
for radioactive targets. Indirect techniques have been developed to determine reaction rates for
systems that are particularly difficult to measure in a direct experiment. One of the indirect
techniques involves measurements of Asymptotic Normalization Coefficients (ANCs) which
determine the direct-capture contribution to a capture reaction. Also ANCs can be used to
understand the role of subthreshold states in stellar capture. This essay gives an introduction to
ANCs and describes how they are used in nuclear astrophysics. Examples are given of
measurements which have been carried out with both stable and radioactive beams.
© EAS, EDP Sciences 2007