Some external neutron and gammasource experiments were carried out to study the origin of the background.
还应用外置伽玛源和中子源进行了实验，以判断本底的来源。
2
Sealed neutron source and gammasource used in nuclear logging have strong radioactivity which is harmful to operators.
核测井使用的密封中子源和伽马源具有较强的放射性，对操作人员有一定的辐射损伤。
3
It would seem sensible to seek the source of these in the universe's most conspicuous energy factories: quasars and gamma-ray bursts billions of light-years away from Earth.