Yes, material concentration and composition. Isotope impurities are like a fingerprint.
More interesting is the question how they could find where the raw material is stored. This is a complete difficult and demanding task. I suppose X-37B is the key to that question.
Neutron bomb is a nuclear bomb…
Maybe just as a proof of concept.
It was designed to kill large infantry divisions - this type of warfare is over. Would be a total waste of fission material to build and use this type of weapon.
All these shills that claim it was used in Yemen or any other place - please go fuck yourself!
This kind of weapon wold definitely trigger any neutron detector - and there are many distributed all over earth and space. It is part of a network designed to find rouge nuclear weapon test.
EU providing technology and cover. EU is the middleman in all of this.