Small Business Q&A: Nobel Prize Winner for Physics, Arthur McDonald

This week Kehlan talks with the 2015 Nobel Prize Winner for Physics, Arthur McDonald, about winning the award and how he got it for his ground-breaking work with neutrinos - one of the least-known sub-atomic particles.
Small Business Q&A: Nobel Prize Winner for Physics, Arthur McDonald

You’re a Nobel prize winner; how does that feel?

Well, it’s a little bit different; we’re still pinching ourselves here. It’s certainly been interesting.

You won the prize along with Takaaki Kajita from Japan, what was your research?

Well, actually they were two separate experiments, one taking place in Canada and the other taking place in Japan.

They were large international collaborations.

In our case it was an involvement of Canada, the US and the UK.

About a hundred and something scientists worked on the project at any given time, plus the total number of authors on the final paper was 262.

So it’s been a big consortium carrying out the research.

What we measured was the properties of neutrinos which are, as you can imagine, outside the realm of what we see and consider every day.

They are, alongside electrons and quarks, the basic building blocks of matter.

And our research measured these basic properties.

Give us a quick physics lesson, what are neutrinos and why are they important?

They were first proposed because there was a missing element in a certain form of radioactivity.

So the effect was to have an unknown particle, which is very difficult to detect.

Neutrinos only feel the very weakest of all forces of nature which is, believe it or not, called ‘The Weak Force’.

This means they can pass through an enormous amount of material without interacting with it.

They only stop if they hit the nucleus of an atom or an electron going around it.

So, in our case we had to build detectors the size of a ten-storey building, two kilometres underground in order to get rid of interference from cosmic rays and radiation that we get on the surface.

This was needed just to detect one neutrino an hour.

They are very difficult to detect even though we know they are made extensively within the nuclear reactions that power the sun.

To give some kind of context — if you hold out your thumb and count to three, by the time you reach three, two hundred billion neutrinos will have gone through your finger.

We were able to measure the fact that neutrinos actually change from one type to another.

This cannot happen unless they have a finite mass, a mass greater than zero.

And that is actually outside what we know of the standard model of physics.

So, now we have some clues as to how this theory can be extended to try and explain our universe.

Was the discovery like a ‘eureka’ moment or putting the pieces of a jigsaw together?

It was a little bit of both.

We had been working on this for 20 years and in that time we had built a big detector underground in a mine and tried to keep that detector itself as radiation free as possible.

But when it came to actually making the measurements we purposely put in extra unknown elements into the analysis of the data.

This meant that our analysers had to work out the data and couldn’t be led by the nose to the data that gave us the conclusion we were looking for.

Then one day we pulled those unknown elements from the criterion and ended up with a ‘eureka’ moment.

The discovery was significant and was clear to all involved what it meant.

Neurtrinos change from one type to another and have a finite mass.

So, over a hundred different physicists all at once shared in this ‘eureka’ moment.

Is this part of a lifelong work for you?

I’ve been interested in science since I was a kid.

I’ve done physics and research since I was in University and also became a University Professor.

Two thirds of those involved in the project were university students and post-doc students coming through the research experience.

So what’s next with this research?

I’m involved in a number of other measurements that are taking place at an expansion of our underground laboratories.

It’s been recognised, now, that this type of physics is a very important part of particle physics.

For example, the whole of Fermilab, a major accelerator in Chicago, is devoted to measurements of neutrinos and their properties.

They’re trying to understand how they fit into our universe as a whole.

But, in our case we’re looking at further properties of the neutrinos in this very low radioactivity background.

We’re looking for rare types of decays which happen once every few million years, but you have to collect more than that in atoms in order to create viable research.

That means many tonnes of materials and then wait for a number of years in order to see these decays working.

The importance of this is in looking at our early universe.

We need to see what influence they had in the forming of matter.

We believe that our universe was born with matter and what is known as antimatter.

However, what seems to have happened is that antimatter seems to have decayed away and so we are left with matter and building blocks to the matter we see around us.

The other research we’re looking at also involves that mass we talked about earlier.

So, now that we know these tiny particles, neutrinos, have a finite mass it is still too small a mass to explain what is holding our galaxies together.

The smaller we go, the bigger the machines to detect them get, is that scale and cost a big stumbling block to this kind of research?

That’s very true. One the big missions of CERN, these days, is to try to create, for the first time, those heavier particles — or dark matter particles — which haven’t been created since the Big Bang.

So there is a great complement to what we’re doing and also what they are doing in their research too.

But it turns out that the way in which things happen in research, you really have to increase the energy of what you’re dealing with in order see the resolution better.

It’s the reason why the likes of electron microscopes are much better at observing than microscopes that use light to see.

The effect is that the smaller you the more power you need in order to view properly what your trying to see.

That is why international collaboration is so important to science, where the cost is burdened by many rather than one country or a few countries.

Follow Kehlan on twitter at @KehlanK

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