Neutron Capture Cross-Section Measurement of 99Tc by Linac Time-of-Flight Method and the Resonance Analysis

Abstract

The neutron capture cross section of 99Tc has been measured relative to the 10B(n,αγ) standard cross section by the neutron time-of-flight (TOF) method in the energy range of 0.005 eV to 47 keV using a detection assembly of Bi4Ge3O12 scintillators and a 46-MeV electron linear accelerator at the Kyoto University, Research Reactor Institute. The relative measurement has been normalized at 0.0253 eV to the reference value (22.9 ± 1.3 b) measured by Harada et al. The energy-dependent experimental data and the evaluated data in ENDF/B-VI, JENDL-3.2, JENDL-3.3, and JEF-2.2 are in general agreement with the current measurement. In particular, the JENDL-3.3 data, which have been released recently, show better agreement with the measurement in the lower-energy region.The resonance parameters at 5.6 and 20.3 eV have been analyzed by the KALMAN system using the current TOF data. The resonance integral calculated with the parameters obtained is derived to be 330 ± 19 b, which is close to the data obtained from JENDL-3.3 and evaluated by Mughabghab, although the resonance integrals from JENDL-3.2, ENDF/B-VI, and JEF-2.2 are smaller by ~6 to 8% than the current value. The resonance integral data measured by Harada et al. is larger by ~20%.