High precision time-of-flight measurements of neutron resonance energies in carbon and oxygen between 3 and 30 MeV

Abstract

An essentially improved time-of-flight device has been set up at the Karlsruhe isochronous cyclotron. Transmission measurements on carbon and oxygen in the energy range from 3–30 MeV with a spectrometer resolution of 5.5 ps m −1 allowed neutron resonance energies of some narrow resonances to be determined with an accuracy of 1.2 × 10 −5. The present results are in many cases more accurate than previously published values by more than two orders of magnitude. Above 10 MeV measured excitation energies of various T = 3 2 states in 17O have an order of magnitude higher accuracy than the most precise determinations from charged particle reactions. Resonance energies and widths of narrow neutron resonances are presented and two sets of data suitable as high precision energy standards are proposed. For the 16O+n system energies and total widths are given of four T = 3 2 states in the range 7⩽ E n⩽11 MeV.