Measurement of 4.438 MeV γ-ray to Neutron Intensity Ratio for Am-Be Neutron Source

The present research concerns in the accurate measurement of the 4.438 MeV γ-ray to total neutron intensity ratio, namely R=S_γ/S_n, for homemade Am-Be neutron source. The neutron strength of the source relative to a previously standardized source was determined by the manganese bath technique. The γ-ray spectra of the source were measured using a Φ75 mm×75 mm NaI(Tl） detector. The background induced by neutrons and the absolute full energy peak efficiency of the detector were calculated using the MCNP code. The experimental ratio obtained agrees well with the calculated value. A synthetic evaluated and recommended value of R=0.575（1±4.8%） was given. The experimental R value appears an important characteristic for the Am-Be source.