“Australia was involved in the design and testing, and a little bit of the construction, of the silicon tracker which is in the centre of the ATLAS detector. It basically shows where the particles go after they emerge from a collision.”

ATLAS has around 35 tonnes of copper shielding that was machined in Australia and shipped to the research facility near Geneva, which opened in 2008 as the world’s fastest particle accelerator.

Australia is involved in monitoring the ongoing experiment - which smashes together beams containing billions of protons traveling near the speed of light - and it also hosts one of the computer farms used to process its mountain of data.
ATLAS generates enough information to fill 100,000 CDs per second however it only records data that might show signs of new physics - which amounts to about 27 CDs-worth per minute.

“A lot of the actual number crunching is done in large computer farms – there is one in Australia attached to the University of Melbourne,” says Associate Professor Varvell.

“It used to be the case that these big experiments could be done in the CERN computer centre but with the LHC, the size of the task now is so large the data is farmed out all over the planet. It is very much a global effort these days.”

The ATLAS experiment has involved physicists from 174 institutions, and 38 countries.

Australia’s involvement in the LHC is co-ordinated by the CoEPP - a body which brings together experts in high energy particle physics from the University of Melbourne, Monash University, the University of Sydney and the University of Adelaide.

CoEPP director Professor Geoff Taylor says this signalled a new phase in Australia’s relationship with the LHC which has spanned more than 20 years and there was more work to do in the future.

“It was R&D in the beginning, then development of the prototypes and engineering then installation,” says Professor Taylor from the University of Melbourne. 

“Now we’re contributing to the operation of the detector and in the coming years we’ll start a project for the upgrade. We have played a relatively strong role for a small country, a small group.”

The latest batch of ATLAS data will be presented at the ICHEP 2012 conference in Melbourne (4 – 11 July).

It will presented along with data from the CMS experiment, also underway at the LHC and which is independently looking for signs of the Higgs boson.

There are hopes this data will enable physicists to conclusively prove, or rule out, its existence.

BACKGROUND INFORMATION
The ARC Centre of Excellence for Particle Physics at the Terascale (CoEPP) was established in February 2011, to work on global endeavors in high energy physics, advanced computing and accelerator science.

The Australian Research Council’s funding commitment is for $25 million over 7 years.

This currently supports the work of more than 20 senior investigators and 60 students or post-doctoral researchers.

Melbourne Node Director is Professor Ray Volkas
Monash Node Director is Associate Professor Csaba Balasz
Adelaide Node Director is Professor Anthony Thomas
Sydney Node Director is Associate Professor Kevin Varvell.

CoEPP Centre Director is Professor Geoff Taylor.

Register for ICHEP as press:
http://www.highenergyphysicsmedia.com

Follow the news as it breaks:
We’ll be tweeting on @pressichep, and you can follow the hashtag #ICHEP2012

Conference:
http://www.ichep2012.com.au
4–11 July, Melbourne Convention and Exhibition Centre

Key contact details:
Conference media director:
Niall Byrne, 0432 974 400, niall@scienceinpublic.com

Why is finding it so important?
Scientists have a developed a rule book of how elementary particles and forces interact in the universe – a “Standard Model” for particle physics.
This rule book stops short of explaining how matter gets its mass and so the Higgs boson theory is seen as the key missing piece of the puzzle.
The Standard Model would have to be rewritten, or junked altogether, if the Higgs boson was proven to not exist or found to operate in a different way than the theory suggests. 
Resolving this question would hand scientists a powerful new tool they could use to probe the universe’s other big mysteries – such as the nature of dark matter.

Where are scientists looking for proof of the Higgs boson?
The Higgs Boson cannot be easily observed.
Physicists have turned to experiments which involve smashing together beams containing billions of particles, at high speed and within a vacuum, and watching the results.
It is thought some of the new particles created during these collisions may be Higgs bosons, though they rapidly decay into well-understood particles.
This work is continuing in a bid to find conclusive proof.
More powerful particle accelerators have also been built to speed up the search, with the biggest to date being the Large Hadron Collider (LHC) which came online in 2008.
The LHC runs 27km in a circular tunnel, is built 100 metres underground near the Swiss - French border, and accelerates particles to speeds previously not obtainable.

What do we think the Higgs boson does?
One analogy used to explain how the theory of the Higgs field, and its Higgs bosons, operates involves a cocktail party and a popular hostess.
Guests at the party are uniformly distributed across the room, all talking to their nearest neighbours.
The hostess enters the room, and all those nearby are strongly drawn to her and cluster around her. 
As the hostess moves she attracts the guests she comes close to, while the ones she has left return to their even spacing.
Because of the knot of people always clustered around her she acquires a greater mass than normal - that is, she has more momentum for the same speed of movement across the room.
Once moving she is harder to stop, and once stopped she is harder to get moving again because the clustering process has to be restarted.
The guests at the party are Higgs bosons and the hostess is a particle of matter.

Why could the Higgs boson be found soon?
After years of searching, an end appears to be in sight.
In December 2011, the first full year of data arising from particle smashing experiments at the LHC was released.
These results – combined from two major studies ATLAS and CMS - provided tantalising signs of the Higgs boson but fell short of conclusive proof.
The research has continued at the LHC this year, and another major batch of data has been added to the earlier analysis.
The updated result will be made public in Melbourne at the 36th International Conference on High Energy Physics (ICHEP 2012, 4 – 11 July).
It may conclusively point to the Higgs boson or something altogether different. 
A mystery that has withstood almost 50 years of scientific inquiry could soon be solved.

Why was the Higgs boson data released last year not conclusive? 
Physicists are doing everything they can to rule out the likelihood of random chance leading them down the wrong path.
Analysis of the LHC data available in December last year, which pointed to a possible Higgs boson, was deemed to be inconclusive because chance could not be sufficiently ruled out as a factor affecting the result.
The analysis had a “three-sigma” confidence rating  - meaning the result has a 0.13% possibility of being due to chance.
Physicists generally wait for a “five-sigma” confidence rating – 0.000028% possibility of a chance result – before they declare a discovery.
The data set that will be analysed and presented in Melbourne has more than doubled in size since the December 2011 result, so chance is much less likely to be an issue this time around.  

Either outcome would have major ramifications for our understanding of the basic laws which govern the universe, explains Professor Geoff Taylor from the School of Physics at the University of Melbourne .

“The existence or not of the Higgs is an absolutely pivotal moment and so what-ever happens, the importance of this announcement cannot be understated,” says Prof Taylor, who is also director of the ARC Centre of Excellence for Particle Physics at the Tera-Scale.

“The data also has implications for our understanding of other unexplained questions, like how gravity operates at the quantum level and the nature of dark matter and energy, so this is a major step along the way to even bigger questions.”

The Higgs boson is named after theoretical physicist Peter Higgs who, in the 1960s and along with other scientists, came up with a theory to explain how the fundamental building blocks of matter in our universe have mass.

Finding it would not only confirm this theory but also fill in a major missing piece of the “Standard Model” of particle physics - the book of fundamental rules the universe is thought to operate by but which has remained silent on how particles gain their mass.

Conversely, ruling out the Higgs boson would require physicists to “start looking for something exotic”, Prof Taylor says, and “a major revision to the Standard Model which is also big news”.

The LHC  - a particle accelerator built in a 27km loop underground near Geneva - was completed in 2008 though teething problems have hindered researchers in their particle smashing efforts to find the Higgs boson.

Its first full year of data was presented in late 2011, and Prof Taylor says this offered “tantalizing evidence but it was not really enough to make a strong statement”.

“This year, the LHC has been operating very well again, and we have more than doubled the total data set and at a higher energy level,” Prof Taylor also says.

“So we’re very sure that the results that we’re going to see at the conference will be vastly improved over the tantalizing results of December.”

The results will include all data captured and analysed to date from two separate Higgs boson-probing experiments (ATLAS and CMS) underway at the LHC.

The data is compiled via a “black box” process that keeps the ultimate finding a secret until needed, and to ensure the physicists involved cannot unintentionally sway the result.

“It’s a “double-blind” analysis and we haven’t opened the box yet so we don’t know what we’re going to get,” Prof Taylor said.

“… but there are indications that it is going to be an important result, and we have a major result on our hands whichever way it goes.”

ICHEP is the preeminent physics conference. Held once every two years, this is its first visit to Australia.

Recent ICHEPs have been held in Paris (2010), Philadelphia (2008), Moscow (2006) and Beijing (2004). The first conference was held in Rochester, New York in 1950.

Register for ICHEP as press: http://www.highenergyphysicsmedia.com

Follow the news as it breaks: We’ll be tweeting on @pressichep, and you can follow the hashtag #ICHEP2012

Conference: http://www.ichep2012.com.au

4–11 July, Melbourne Convention and Exhibition Centre

Key contact details: Science in Public will be assisting run the media program for the conference.

For more information, contact Niall Byrne on +61 (417) 131 977, or on niall@scienceinpublic.com.au  or AJ Epstein on +61 (433) 339 141 or aj@scienceinpublic.com.au

ARC Centre of Excellence for Particle Physics at the Terascale

Caroline Hamilton, 0478 402 765, hamc@unimelb.edu.au