NARRATION
September 11 had a profound effect on our lives in many ways.

Dr Graham Phillips
One of the legacies of those horrific events is of course airport security.

NARRATION
We are now subjected to more scans and checks than ever before. But what about air cargo? Eighty percent of air freight travels on passenger planes, with us. Does it get subjected to the same level of security?

Dr Nick Cutmore
The scanning of air cargo is a pressing problem that's been around for a very long time. A lot of sea cargo does get scanned around the world. In terms of air cargo, not a lot.

NARRATION
Since 9/11, scientists at CSIRO have been developing an air freight scanner to address this security gap.

Dr Graham Phillips
So this is the first system you put together?

Dr Nick Cutmore
Yep no this is the first scanner that we built. What's special about this scanner is that it combines neutrons and x-rays together to give you a much clearer picture of the, what's inside the cargo containers.

Dr Graham Phillips
So traditional ones only use x-rays is that right?

Dr James Tickner
Yes normal systems will be based around x-ray alone.

Dr Graham Phillips
Oh okay. So how do you generate the neutrons? Where does that happen?

Dr James Tickner
They're made using a system called a neutron generator. That's actually buried deep inside this concrete block which just shields the radiation from getting out. This uses a fusion reaction. It's very similar to the reaction that goes on in the heart of the sun.

Dr Graham Phillips
So x-rays out of one, neutrons out of the other?

Dr James Tickner
Yep that's correct. So the, the skinnier slot's where the x-rays come out, the wider slot there is the neutrons. 

Dr Graham Phillips
So it's just sort of shooting out beams of these?

Dr James Tickner
Yep. So we get one line as it were one, one row in an image and then as we move the cargo through the beam, row by row we build up a picture of what's inside the container.

NARRATION
The neutrons are sensed by a bank of detectors within the scanner.

Dr Graham Phillips
These are components of the detector?

Dr James Tickner
Yep that's correct. So we start off with a piece of this. This is the scintillator material. So we fire a neutron in here and the neutron gets turned into a little flash of light that we can then pick up with our electronics. Here we have a bank of sixteen and then we have the electronics that converts the light into an electrical pulse, we have a digital chip to count those pulses and then that connects through to a computer. It's quite similar to a, a digital camera. We have these scintillators making the light, we have a whole array of pixels and that's what we use to build up the image.

Dr Graham Phillips
So if we just had x-rays, that's what the image would look like?

Dr James Tickner
Yep. It shows the shapes of the objects in the cargo quite clearly but you have no idea what they're actually made from. But if we bring in the neutron information then we get a full colour image.

Dr Graham Phillips
Oh look at that yeah.

Dr James Tickner
Now the way it works is the neutrons and the x-rays together lets us pick out different classes of material, different types of material in the cargo and then we use different colours to show those materials to the operator.

NARRATION
With the neutrons, the scanner can distinguish up to two hundred and fifty different types of substances. 

Dr James Tickner
So for example we've got some computer equipment here on the left showing up sort of green from the glass in, in the old fashioned computer monitor there, we've got metal parts, steel parts showing up in blue and then we've got some food stuff showing in red and we've got paper and files showing up in orange.

Dr Graham Phillips
So you could pick the difference between say a bag of explosives and a bag of flour?

Dr James Tickner
Yep no they'd show up quite clearly as being different colours.

NARRATION
Ironically, it's using nuclear technology to make the world a safer place.

Dr Nick Cutmore
Neutrons bring a new dimension into the, the areas that we've formed, we're able to better identify objects that are not meant to be in the cargo, various contraband items.

NARRATION
Two of the scanners are in operation at Abu Dhabi and Belgrade airports, and the team is about to roll out their latest version, the Mark 3. 

Dr Nick Cutmore
It's made in China by our partner, Nutech. The technology really is fundamentally the same. The things that have changed are in the shielding. We're using recycled rubber rather than concrete, we're using smaller neutron generators and we're now using a whole system that we put in place a lot quicker and is easier to maintain.

Dr Graham Phillips
So we now have a device that will help close the gap in air security. Let's hope it comes to an airport near you and me soon.

STORY CONTACTS

Dr Nick Cutmore 
Project Leader
CSIRO, NSW

Dr James Tickner 
Science Leader
CSIRO