Nuclear Data for Nuclear Astrophysics

Nuclear astrophysics involves study of the synthesis of elements and the evolution of cosmic sites where such syntheses occur. Systems as diverse as the early universe, the interstellar medium, red giant stars, and supernova explosions are currently the focus of intense studies utilizing sophisticated computer models -- models which require large quantities of nuclear data as input. Measurements in the nuclear laboratory form the empirical foundation for the current models of element synthesis. These models require, in general, the rates of and energy released in nuclear reactions occurring in astrophysical environments. The rates are derived from laboratory measurements of cross sections of relevant reactions -- primarily fusion, transfer, and decay reactions -- convoluted with a thermal (Maxwell-Boltzmann) relative velocity distribution; the released energies of the relevant reactions (Q-values) are derived from measurements and calculations of masses. Additionally, models require structural information on properties of relevant nuclei, such as one- and two-particle separation energies, single-particle energy levels, level densities, partition functions, and parameters of resonances near particle capture thresholds.

There are a number of existing evaluations of nuclear data important for astrophysical models. A comprehensive collection of available nuclear astrophysics datasets can be browsed at www.nucastrodata.org.

One dataset, the REACLIB reaction rate library, contains over 60,000 thermonuclear reaction rates. An online viewer RatePlotter for these reaction rates is also available.

Another very important collection of thermonuclear reaction rates was assembled by Willy Fowler and collaborators. The last in this series is by G.R. Caughlan & W.A. Fowler, published in At. Data Nucl. Data Tables, vol. 40 (1988) 283. With the permission of the journal, we have put these reaction rates online in the format as they appeared in print: a text file of reaction rates as analytic functions of temperature, and tables of rates values versus temperature for each reaction. Additionally, we have extended the utility of this compilation by creating a graphical interface to select rates using the table of isotopes, and by posting GIF and Postscript plots of each rate, a downloadable fortran subroutine of all the reaction rate formulae, analytic expressions for temperature derivatives of these rates, and a downloadable fortran subroutine of the reaction rate derivatives.

A number of reaction rates have been updated since the publication of the Caughlan and Fowler 1988 compilation. Most notably, the NACRE Collaboration revised the evaluations of approximately half of the rate collection. Additionally, we have posted a 1997 evaluation of the ¹⁴O(alpha,p)¹⁷F and ¹⁷F(p,gamma)¹⁸Ne Reaction Rates , a 1992 evaluation of Big Bang Nucleosynthesis Reaction Rates, along with information on other updated reaction rates.

We have also compiled a Nuclear Astrophysics Bibliography which contains over 1200 references for a wide range of topics in Nuclear Astrophysics. This list is meant to be complementary to the nuclear physics articles listed in the Nuclear Science References at the National Nuclear Data Center and to the astrophysics articles listed in NASA's NASA's Astrophysics Data System. The references are arranged alphabetically within subtopics.

An overview of the current status of nuclear data for nuclear astrophysics is given in M.S. Smith, Nuclear Physics A718 (2003) 339c.