Prompt Gamma Rays Emitted in Thermal-neutron Capture Reaction by ⁹⁹Tc and Its Reaction Cross Section

Abstract

We have studied the primary and secondary γ rays (a total of ~1,100) in ¹⁰⁰Tc following thermal-neutron capture by the radioactive ⁹⁹Tc isotope. A fraction of these γ rays have been incorporated into the corresponding level scheme consisting of 36 levels in ¹⁰⁰Tc. The determined neutron separation energy (S_n) for ¹⁰⁰Tc is 6,765.20±0.04keV. By summing the cross sections of all ground-state transitions, we have obtained 21,37±0.68 b as a lower limit of the thermal-neutron capture cross section for ⁹⁹Tc. We have also determined the capture cross section by examining the 540-and 591-keV γ rays in ¹⁰⁰Ru emitted following the β⁻ decay of ¹⁰⁰Tc. The inferred thermal-neutron capture cross section for ⁹⁹Tc is 22.8±1.8b.

KEYWORDS:

• thermal neutron
• capture reaction
• cross section
• technetium 99
• prompt gamma ray
• ground-state transitions
• primary gamma rays
• separation energy