Novel Method to Study Neutron Capture of U-235 and U-238 Simultaneously at keV Energies

作者：Wallner A^*; Belgya T; Bichler M; Buczak K; Dillmann I; Kaeppeler F; Lederer C; Mengoni A; Quinto F; Steier P; Szentmiklosi L

来源：Physical Review Letters, 2014, 112(19): 192501.

DOI：10.1103/PhysRevLett.112.192501

The neutron capture cross sections of the main uranium isotopes, U-235 and U-238, were measured simultaneously for keV energies, for the first time by combining activation technique and atom counting of the reaction products using accelerator mass spectrometry. New data, with a precision of 3%-5%, were obtained from mg-sized natural uranium samples for neutron energies with an equivalent Maxwell-Boltzmann distribution of kT similar to 25 keV and for a broad energy distribution peaking at 426 keV. The cross-section ratio of U-235(n,gamma)/U-238(n,gamma) can be deduced in accelerator mass spectrometry directly from the atom ratio of the reaction products U-236/U-239, independent of any fluence normalization. Our results confirm the values at the lower band of existing data. They serve as important anchor points to resolve present discrepancies in nuclear data libraries as well as for the normalization of cross-section data used in the nuclear astrophysics community for s-process studies.

• 出版日期2014-5-14