Disarmament contracts often make it unclear whether weapons have been destroyed. Researchers at MIT developed a measurement method using neutron beams to analyze nuclear weapons without revealing any military relevant details.
At the beginning of 2019 and according to estimates by various non-governmental organizations, there were almost 13,900 nuclear weapons spread across nine countries. The two military superpowers Russia and USA have by far the largest arsenal of around 6,000 warheads. France (300), China (290), Pakistan (155), India (135), Israel (85). North Korea (25) have deployed these weapons of mass destruction on site and yet we are not certain about final numbers.
The Stockholm Peace Research Institute SIPRI is observing two trends: Many states with nuclear weapons modernizing their arsenals. The same time, the total number of nuclear warheads is falling. But how do weapon inspectors check whether an atomic bomb has been dismantled? For the most part when countries sign agreements, usually don’t give inspectors full access to their nuclear technologies for fear of revealing military secrets. Researchers at the Massachusetts Institute of Technology (MIT) closing this gap with a new test method based on neutron beams.
Disarmament: No proven measuring method
Politicians use dubious methods to check whether disarmament treaties are being followed. For example, earlier agreements between the United States and Russia agreed to destroy launchers for nuclear warheads, such as missiles and aircraft, but not to deactivate the warheads themselves. For example, to comply with the START contract, the United States destroyed and released B-52 bombers back in the Arizona desert, where Russia could confirm this via satellite images.
MIT researchers have now tested a new high-tech measuring technique that inspectors use to prove the destruction of nuclear weapons. Her method works with neutron beams to determine certain facts about the warheads in question and crucially uses an isotope filter that physically encodes information in the measured data. Inspectors get basic facts without revealing military secrets.
Typical properties of plutonium
Nuclear warheads contain various plutonium isotopes. In order for weapons to actually work various roughly known geometries must be included. The experiments consisted of first sending a horizontal neutron beam through a proxy functional pattern of the warhead. Molybdenum and tungsten are two metals that share important properties with plutonium, were suitable for the simulation. Actually is really simple soluotion: the signal of the beam is sent to a lithium glass detector where a signature of individual data is recorded.
The test works mainly because the neutron beam identifies the isotope in question. “In the low energy range, interactions of neutrons with the material are extremely isotope-specific, so you take a measurement that gives you information about the isotopes and the geometry. But you take an additional step that physically encrypts data.
More acceptance through new encryption method?
The physical encryption of information from the neutron beam called by Danagoulian enables scientists to recognize essential details and carry out comparisons. However, militarily relevant secrets remain hidden: an argument why the nuclear researcher hopes to gain more acceptance from politicians compared to the past.
It would theoretically be possible to send the neutron beam through a warhead, record all information and then digitally encrypt it. We are touching main problem when computers are known for vulnerabilities. They can be hacked while the laws of physics are immutable. The presented physical process is also not reversible.
Local inspectors unmask dummy warheads
During a weapons inspection, the host country gives experts a warhead. Then follow neutron beam tests to see if it is really part of a nuclear weapon. Before and after comparisons of the physical signatures show the success of dismantling. The Commission can also distinguish genuine from counterfeit components. It’s already happened that the military presented an original warhead, but only dummies were destroyed afterwards.