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Virtual atom smasher in LHC@Home 2.0

“When I learned that if successful, LHC@home 2.0 would allow BOINC users to participate in physics experiments being done at CERN - and ultimately perhaps even the search for the Higgs Boson itself - I jumped at the chance to be a part of it,” said Tony De Bari.

What is BOINC?

BOINC (Berkeley Open Infrastructures for Network Computing) is an open-source software platform for computing with volunteered resources. It was first developed at the University of California Berkeley to manage the SETI@Home project, and uses the unused CPU and GPU cycles on a computer for scientific computing.

De Bari, who is from New Jersey, USA, joined the project in February 2011, after finding out about it from forum posts online and emailing the developers to ask for an invitation code.

De Bari now has three computers, at work and at home, contributing time to the LHC@Home 2.0 project. “Even though I do not have a formal physics background, I am a self-proclaimed ‘science geek’ with a particular interest in physics. While pursuing my computer science degree, I took as many elective physics courses as time would permit, and I try to read as much about the subject as I can.” 

The developers hope LHC@Home 2.0 will be used for several research projects in the future. The first project, called Test4Theory, has been in the alpha testing phase since October 2010, and now has more than 100 volunteers just like De Bari. Even at this early stage, volunteers have already provided about 10% of the total computing resources currently available to theoretical physicists at CERN according to Anton Karneyeu, one of the developers on the project who also works on the CMS experiment.

Sharing computing power

CERN may be the epicenter of the Worldwide LHC Computing Grid (WLCG), one of the largest distributing computing networks in the world - containing about 250,000 processing cores distributed across 36 countries – but the resource is almost exclusively for the use of the experiments (ATLAS, CMS, ALICE and LHCb) which pump data out of their detectors at about 300 MB per second.

The computational power available to the theoretical physicists, by comparison, is minor: about 50 theoretical physicists at CERN share a small computing cluster.

“I think we can get 10,000 or maybe more [people participating in Test4Theory]. This would make a real difference to the resources available to theoretical physicists,” said Peter Skands, the theoretical physicist who, together with the developers of LHC@home 2.0, came up with the idea for Test4Theory about a year ago.

simulating events in particle physics using Monte Carlo simulations

Image courtesy Wikicommons

Generating random events

Skands uses Monte Carlo simulations to determine the rate at which specific events should occur in the experiments. Monte Carlo simulations, named after the area in Monaco famous for its casinos, generate explicit random numbers. For example, you could use a Monte Carlo simulation to generate a string of one million dice rolls, and for each roll you know you would get a number between 1 and 6, but it could also be random and independent of the other rolls.

Similarly, in relativistic quantum field theory - the theory that combines quantum mechanics with special relativity and describes the particle physics being explored at the LHC - the particles are governed by probabilities, the probability of being in a certain state or the probability of interacting in a certain way.

The Monte Carlo simulations generate specific events randomly, based on the probabilities that define the interactions. The simulation can also be extended to include hypothetical new laws of nature, and results compared to data, to find which hypothesis fits best.

If a particular event is extremely rare – like rolling a die a million times and getting a one every single time – then a lot of simulations are required in order to find it. And “generating these random events to find that one-in-a-million, exceptionally rare one requires a lot of computing power,” said Skands.

Extremely rare events in particle collisions

Unfortunately for physicists, it is the rare events that are the most interesting in the study of particle interactions. For example, in April this year, Fermilab’s Tevatron in Illinois, USA, reported a mysterious bump in their data that, as claimed at the time, could point to new elementary particles or even a new force of nature.

Two protons colliding can create bottom (beauty) and anti-bottom (anti-beauty) quarks. Gluons can interact, making some interactions rarer.

In a proton-proton (grey circle, 'p') collision, the color force is mediated by gluons (curly lines). Gluons can produce a quark and an anti-quark (b and anti-b). Unlike the electrically neutral photons that mediate the electric force, gluons actually carry a color charge themselves and so they can interact with other gluons, as illustrated by the lower diagram. This makes quantum chromodynamics much more difficult to simulate and to analyze than quantum electrodynamics. Image courtesy Peter Skands and Jacqui Hayes.

What the proton-antiproton collisions had produced is called a W-jet-jet (Wjj) event: two jets of lightweight particles, called hadrons, and a heavy-force-carrying particle called the W boson (about 85 times heavier than the proton). However, extremely rare events in quantum chromodynamics can mimic such a signal, and must be accurately understood to determine if there is really a signal of something new in the data. The physicists are still studying these events, and the jury is still out.

Another event modeled with computationally expensive Monte Carlo simulations is the generation of beauty and anti-beauty quarks after a proton-proton collision, as detected in the LHCb experiment; LHCb is designed to study the asymmetry between matter and anti-matter apparent in the universe. After LHCb detects and records the quark pairs, the physicists compare these measurements to what is predicted by theory.

The CERN 'virtual machine'

To help with these simulations, volunteers must first download VirtualBox, which is free software from Oracle to allow a virtual machine to run on their home computer. The virtual machine is a ‘computer within a computer’, complete with its own operating system.

The VirtualBox system allows someone with a Mac operating system or Windows on their home computers to run a Scientific Linux virtual machine (VM) called CernVM, which runs the software that almost all the experiments and theorists at CERN use. This virtual machine can then communicate directly with the CERN experiments and theoreticians using software called Co-Pilot, developed by Artem Harutyunyan at CERN.

“The best thing about this set-up,” said Ben Segal, one of the lead developers behind LHC@Home 2.0, “is that the physicists themselves don’t have to port their programs or understand BOINC. They see all the volunteer machines as part of a Volunteer Cloud. It can support all the LHC experiments as well as the theorists.”

How to get involved in LHC@home 2.0 and Test4Theory

Volunteers can download a package, compressed to about 200 MB, which consists of BOINC software, a CERN virtual machine and some ‘wrapping’ code that acts as the interface between the home computer and the virtual machine.

Volunteers helped beam design

This is not the first volunteer computing project from CERN. The first, called SixTrack, was deployed in 2004 as part of the first version of LHC@home, and would typically simulate about 60 particles whizzing around the collider’s ring for 10 seconds, or up to million loops. SixTrack helped the engineers at CERN design stable beam conditions for the LHC, so today the beams stay on track and don’t fly off course into the walls of the vacuum tube, causing serious damage.

The wrapping code, previously developed by several CERN students and currently coordinated by Daniel Lombraña González, from the Citizen Cyberscience Centre at CERN, then opens up the virtual machine on the home computer and runs CERN jobs, typically event simulations, via the Co-Pilot link for 24 hours at a time – some jobs may take only and hour or two, and occasionally a single job may take up the entire 24 hours.

Though computing some of the events may have taken several hours, it ends up taking only few minutes to transfer the final files back to CERN. Every 24 hours the volunteers receive BOINC credit for their work.

New opportunities for BOINC

The use of virtual machines is new for BOINC projects. The wrapping code will likely be used for future projects at CERN and elsewhere, said Lombraña González.

The volunteers were encouraged to actively participate in this part of the project as well. “The most exciting thing for me is that for the first time in my distributed computing ‘life’, I have the opportunity to help build a project from the ground up, and to help take the BOINC platform into areas where it couldn't go before,” said De Bari.

“[When] a new iteration of the BOINC worker app or virtual machine image are released, not only do we get to find the bugs, but we are encouraged to help develop the solutions as well.  For someone with my background, it doesn't get much better than that,” he said. 

Can volunteers create a virtual atom smasher?

“We would never be able to simulate as many events as the LHC,” Skands said. “The fastest Monte Carlo I have would produce one collision per millisecond, on average. But the LHC produces 40 million per second.”

At this point of our interview, Skands paused and leant back in his chair. “How many volunteers would we need to produce as many events as the LHC?” He shrugged as he said it, and he meant it merely as a rhetorical question, a nod to the incomprehensible size and speed of the LHC. But, as he started to answer his own question, it suddenly dawned on him that he could actually produce a fully-fledged virtual atom smasher if just 40,000 volunteers ran his Monte Carlo simulations at the same time.

Until that point, Skands had been hoping for perhaps 10,000 volunteers on his project.“I never even considered that a possibility before now,” said Skands. “Honest to God, that would be a fun thing to do!”

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this link goes to the lhc@home2 project page

No, that link does not go the LHC@home 2.0 project. That link goes to the old LHC@home project.

For the LHC@home 2.0 project go to and click the NEW! link. The Test4Theory@home project, which is the foundation of the LHC@home 2.0 project, is at Visit that page once in a while and watch the News section of that page. There will be an announcement in the News when they open the doors to more members. You can also subscribe to the news via RSS feed (scroll to the bottom of that page for RSS link).

In the meantime you could install BOINC and join one of the many other BOINC projects to see how BOINC works. The BOINC home page is Click the Download link to download the BOINC software. Click the Documentation link to go to the BOINC wiki to learn how to use BOINC. Careful, there are 2 Documentation links on that page, you want the one at the top of the page. BOINC is NOT your average software. You MUST read the documentation to learn how to use it properly and understand how it works.

When you join more than 1 BOINC project, use the same email address to register at each one. That way your BOINC credits from each project you join will be added to the same account. So, remember the email address you use at the first project you join and use that same address for all the other projects you join.

Happy crunching!

hi how i most help you.?

IT is NOT accepting new accounts, what is the problem??

The server saturated for a while. The developers say they will open for new accounts soon. See the notice about "overwhelming interest" on the project web page

Dear all,

If you want to join the project, please, visit the official web site (, and read the FAQ section if you have any problem. There are step by step instructions on how you can join the project.



I would like to help out with giving up some of my computers spare time. But can't even register for the last 3 days for a new account! On here -

Hi, would like to help, but was told that no new accounts were being accepted.


I just asked the developers and they said they are still accepting new accounts. I am not sure howor why you got that message (perhaps the old LHC@Home project?) but I suggest you try again.

Here is a link to the instructions for LHC@Home 2.0:

Jacqui Hayes
European Editor, iSGTW

Hi, the url you provided worked. I had been selecting the lhc@home project from the boinc list.

Thanks for letting me know, I'll tell the developers. They have been getting multiple queries about this, so they'll be glad to know the source.

Jacqui Hayes
European Editor, iSGTW

I started with Boinc back in 1999 because physics is my main interest and I started with the LHC back in 2004 for a subject that seems more important to me and was there every day even though not much was getting done.

But when I heard about Test4Theory I had to start working on this right away and have been there every day since March 1st checking each task to see how well each version was working and trying to help with this as much as possible.

And Daniel Lombraña González and Ben Segal have been great to work with.

-Samson Ben Yoseph-

I got an invitation to join after I asked for it. I committed six machines to work on the project. One is running nothing but T4T. The others work on a variety of projects using BOINC software. T4T limits any one machine to one Work Unit at a time. I feel that I am a part of and near the birth of something great. Working on a project at this early stage can be painful. Sometimes I get up in the middle of the night to check progress on the machines.

I am grateful to Ben and Daniel for allowing me to be a part of this project and I hope and pray for its success.

Could you supply me the contact. I would like to get an invitation code to get access to the forum.

Hi Guys,
I'm one of the few volunteer testers and I can tell I'm pretty excited about it.
Guess all of the LHC@Home volunteer has been waiting for a long time to see CERN finally harness the full power of volunteer distributed computing and BOINC and it's finally (almost) there.

Working with the CERNVM is not yet so straightforward as it is with any other BOINC-project, but reading this article I came to think it is worth the pain.

Hope CERN will release further science applications!


Very fascinating science indeed!

Are you renaming Test4Theory LHC@Home 2.0 ?

Test4Theory will receive a "proper" name some time during the beta testing (probably with input from volunteers). The LHC@home 2.0 platform is bigger than T4T. We are just the first test project to use it. (Peter Skands, project scientist)

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