Spectral Shape Discrimination for Radiation Detection

A team of nanomaterials researchers at Sandia National Laboratories has developed a new technique for radiation detection that could make radiation detection in cargo and baggage more effective and less costly for homeland security personnel. Known as spectral shape discrimination (SSD), the method takes advantage of a new class of nanoporous materials known as metal-organic frameworks (MOFs). In this video, Sandia materials scientists Mark Allendorf and Patrick Doty discuss their work and the advances in radiation detection it could mean.

Transcript

00:00:16 spectral shape discrimination is a new technique that we've invented that allows us to tell the difference between high energy neutron particles and gamma rays quickly and inexpensively the main application for this is for detecting what we call special nuclear materials that would be

00:00:36 highly enriched uranium and plutonium things that emit neutrons the reason we want to find those things is homeland security we don't want people smuggling those materials but they also have applications in treaty verification and safeguards metal organic frameworks are a little bit like a

00:00:55 chemist's set of tinker toys they are crystalline materials which means that all of the atoms in the crystal are in very specific well-known positions and these moths as we call them have very tiny pores in them nanoporous materials what that allowed us to do in radiation detection is to fill those pores with this other

00:01:16 molecule that emits light out in the red and the green and it allows us to put it in there in a way where we understand exactly how it's interacting with the organic scintillator which has been built into this crystal what we're doing is fundamentally different from the traditional approach because we're actually introducing an

00:01:36 extrinsic dopant into the scintillator material when a high energy particle interacts with an organic material it excites the material that ionized state then collapses back to its ground state and some light is emitted in the blue part of the spectrum what we do is add a second molecule to this material

00:01:58 that interacts with this excited material and emits light of another color the addition of the second luminescent state enables us to do two things one we can manipulate the pulse shape that hasn't been really possible to do before so we can actually engineer the exact pulse shapes that we

00:02:17 think are going to give the best performance the other is because it's two different states we can also make use of the two different wavelengths so we can do color based particle discrimination not just timing based discrimination we've been able to show spectral shape discrimination

00:02:33 by mixing these floors into plastics which are cheap and very standard radiation detection materials so we're looking for partners right now who can help us scale up the synthesis and then actually incorporate that into real detector geometries and test them in the field