The forecast is for SNO+

Tue 29th March 2011

GridPP provides computing for UK particle physicists and this group extends well beyond people working on the LHC experiments. The collaboration has helped many other users get up and running on the grid including T2K, MICE and SuperB. Last week a new particle physics experiment, SNO+, made the first step on to the grid, setting up their Virtual Organisation.

Like the T2K experiment in Japan, SNO+ is interested in neutrinos, SNO actually stands for Sudbury Neutrino Observatory. Building on the success of a previous experiment, simply SNO, scientists hope to use SNO+ to investigate a wide range of physics including neutrino-less double beta decay – a process that probes the fundamental nature and mass of the neutrino.

Interest in the experiment is spread across the UK with Oxford, Sussex, Queen Mary, Liverpool, Leeds and Sheffield all being involved. Steve Biller, Professor of Physics at Oxford University is the UK Spokesperson for the project and is excited by the possible future discoveries “SNO opened the door on a new world of physics, it was the first experiment to establish the bizarre fact that neutrinos can transform into different varieties. SNO+ is the next logical step to further explore that world.”

The heart of SNO+ can be found in the Canadian countryside buried 2km below ground in a working nickel mine close to Sudbury, Ontario at SNOLab. In a cavern, created by the mining which has been going on there for over 100 years, sits a large hollow sphere 12m across. For 8 years, the sphere was filled with 1,000,000 kg of heavy water, borrowed from Atomic Energy of Canada Limited (AECL). When a neutrino interacted with heavy water it created a circular burst of light which could be detected by sensors on the inside of the container. The main benefit of heavy water is that it interacts with all flavours of neutrinos, unlike earlier experiments which only saw electron neutrinos.

The project was extremely successful and extended our knowledge of the “little neutral ones” but, even before SNO had finished, planning began for its successor, SNO+. Having returned the borrowed heavy water, the SNO+ team have begun the process of refurbishing the entire facility and preparing to fill the container with 780 tonnes of a new liquid, linear alkyl benzene (LAB), an organic compound which is less dense than water. The choice to move from heavy water was a simple one to make. For a neutrino to interact with heavy water it has to be pretty energetic and the team knew this meant that there was a whole series of neutrinos which they couldn’t see, including a lot of the ones created by the sun. The use of LAB extends the physics done by SNO into lower energies allowing even more areas to be investigated.
The SNO+ Detector

SNO+ is still being commissioned and is anticipated to take first data in 2012. SNO+ is a relatively small experiment compared to the monoliths like ATLAS but the geographical spread of the researchers and the processing power on offer makes the grid the perfect place to do their work. Dr Jeanne Wilson is the Analysis Coordinator for the experiment and is leading the work of porting their software over to the grid “SNO+ promises a lot of rich physics data but the experiment poses many technical challenges. We need to understand the detector to unprecedented accuracy and hope to use the grid to generate large quantities of accurate Monte Carlo simulations. I also work on T2K, another neutrino experiment that already uses the grid to good effect for sharing and processing data as well as Monte Carlo so realise the potential of this resource for SNO+.”

As 2012 approaches SNO+ can focus on the physics and know that the grid will be ready to process all the data and simulations they need to do now and beyond.

More in depth information on SNO+ can be found:


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