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The fifty trillion particle question

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David Gregory | 10:04 UK time, Wednesday, 20 January 2010

This is a computer display showing the path taken by a neutrino through a detectorThanks to CERN we're used to the idea of physicists sending stuff whizzing about in giant circles. And thanks to journalistic cliché we know they want to do this to "unlock the secrets of the Universe."

But CERN isn't the only place in the world where scientists gather, pushing particles to the limit to expand what we know.

Researchers from the University of Warwick are taking part in a £15m experiment to study mysterious fundamental particles called neutrinos. They're part of an experimental group involving scientists from the Rutherford and Daresbury Laboratories and Queen Mary, Imperial College, Sheffield, Lancaster and Liverpool Universities. You can read more about it here.

There are a lot of neutrinos about, but we know remarkably little about them. As you read this 50 trillion neutrinos from our sun are passing through you every single second and there are more streaming through you from elsewhere. But despite the fact there are so many you've never noticed them of course which gives you some idea of just how hard they are for scientists to detect.

Diagram of the neutrino beam between two Japanese labs 295km apartBut what if you could generate a beam of neutrinos rather than relying on studying the ones from the sun? That would give you a degree of control that would help your research.

And that's what's happening in Japan at a laboratory on the coast called J-Parc. Here they accelerate protons into a target and use them to produce a beam of neutrinos. The scientists then measure the behaviour of the beam at another laboratory almost 300 kilometres away towards the centre of the country called Super-KAMIOKANDE.

As you can see from this diagram because the beam of neutrinos that J-Parc produces travels in a straight line it actually passes right through the earth. At its deepest point a kilometre under ground.

Detector crated up to begin its journeyThe aim of the experiment of is to measure neutrinos at the start of their journey and then again at the end 300 kilometres away and see how they've changed. The result will tell us much about the universe including helping to answer the vexed question of why things are usually made of matter rather than anti-matter.

The team at Warwick have built the detectors which measure the beam as it starts on its journey through Japan. These pictures show the detectors crated up and starting out on their long journey. As you can see it was a squeeze getting them out of the lab at Warwick.

It was a tight squeeze getting the new detector out of the labThe detector on the other end of the neutrino beam at Super-KAMIOKANDE is even bigger though. It's a cylindrical tank, over 40m tall, which contains 50,000 tonnes of ultra-pure water located a kilometre underground in a disused mine. You need a rubber dingy to cross it!

At the moment not all the detectors built by Warwick are in place but the scientists believe they will get useful results in the next run of experiments. Unlike most large scale physics experiments (CERN I'm looking at you) once it's all working we should get a result in a few months. So I can confidently predict in a years time we will know much more about how the universe works.

Or at the very least, we'll know we have to build an even bigger experiment!


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