  Americium-beryllium (AmBe), a well-known tagged neutron source, is commonly
used for evaluating the neutron detection efficiency of detectors used in
ultralow background particle physics experiments, such as reactor neutrino and
diffuse supernova neutrino background experiments. In particular, AmBe sources
are used to calibrate neutron tagging by selecting the 4438-keV $\gamma$-ray
signal, which is simultaneously emitted with a neutron signal. Therefore,
analyzing the neutron and $\gamma$-ray emission properties of AmBe sources is
crucial. In this study, we used the theoretical shape of a neutron energy
spectrum, which was divided into three parts, to develop models of the energy
spectrum and verify the results using experimental data. We used an AmBe source
to measure the energy spectra of simultaneously emitted neutrons and
$\gamma$-rays and determine the emission ratio of the neutrons with and without
$\gamma$-ray emission. The measured spectrum was consistent with that obtained
from the simulated result, whereas the measured emission ratio was
significantly different from the corresponding simulated result. Here, we also
discuss the feasibility of determining the neutron emission rates from the
spectra divided into three parts.
