Measurement of the Thermal Neutron Capture Cross Section and the Resonance Integral of the ¹⁰⁹Ag(n, γ)^110m Ag Reaction

Abstract

In order to develop a neutron flux monitor for long-term neutron irradiation, the thermal neutron(2,200 m/s neutron) capture cross section (≤σ₀) and the resonance integral (I ₀)of the ¹⁰⁹Ag(n,γ)^110mAg reaction were measured by the activation and γ-ray spectroscopic methods. Silver foils were irradiated with and without a Cd shield capsule at the Rikkyo Research Reactor. The Co/A1 and Au/A1 alloy wires were irradiated together with silver foils in order to monitor the thermal neutron flux and the fraction of the epi-thermal neutron part (Westcott's index). A high purity Ge detector was used for the γ-ray measurements of the irradiated samples. The σ₀ and the I ₀ of the ¹⁰⁹Ag(n,γ)^110mAg reaction are 4.12±0.10 b and 67.9±3.1 b, respectively. The σ₀ is 12% smaller than the tabulated one (4.7±0.2 b). On the other hand, the I ₀ is in agreement with the tabulated one (72.3±4.0 b) within the limits of error.

KEYWORDS:

• neutron flux monitor
• thermal neutron capture cross section
• resonance integral
• silver 109
• silver 110m activation method gamma-ray spectroscopy long-term neutron irradiation