CERN Public Computing Challenge 2015

Help scientists simulate particle collisions.
Contribute your computer's power.
Earn challenge credits and badges.
Learn about the origins of our Universe.

Help us translate the instructions into another language.
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About the Challenge

For the “CERN Public Computing Challenge 2015”, CERN is asking volunteers to contribute their spare computing power to help CERN scientists simulate billions of particle collisions, in order to compare theoretical models with experimental results from CERN’s Large Hadron Collider and other particle colliders.

In particular, this one-month challenge is a chance for scientists to test new technologies for distributing and running simulations for the LHC experiments, using publicly contributed computing power. Namely, we’ll be testing new ways of scheduling the simulations we’re sending out, using a CERN technology called Data Bridge, and a new, lightweight version of the CernVM technology which runs the simulations.

For this year’s challenge, CERN is also asking for your help with new communities and social networks, in order to achieve a better gender balance as well as greater linguistic diversity amongst those contributing to the challenge. To help with this, we’re testing a new credit and badging system called CreditPiggy, which we hope will motivate your participation with both individual and challenge-wide statistics about your contributions.

Below you can see the CreditPiggy goals for the whole challenge:

We’ll be sharing our progress towards these goals throughout the challenge, together with details about your own contribution. And if you have any questions, about the science, the software or the social aspects of this Challenge, don’t hesitate to post them in the forum at the bottom of this page.

A bit of history...

The first CERN Public Computing Challenge ran for 12 days in December 2014, as part of CERN’s 60th anniversary celebrations. We invited volunteers around the world to help CERN scientists simulate particle collisions in accelerators like the Large Hadron Collider (LHC), using their own computers. The challenge was an opportunity for us to test new, simpler approaches to distributing such computations, with the help of CERN’s own virtual machine technology, CernVM.

Thanks to efforts of the volunteers, we were able to simulate over 19 billion particle collisions. The results are being used in a new educational game called Virtual Atom Smasher. And thanks to detailed feedback from volunteers, we were able to make big improvements in the software used to manage the challenge.

Join the Challenge

Start Computing

Curious to know what happens when you click this button? Read below!

You install CernVM WebAPI

The first time you join the challenge, you will be prompted to install an application called “CernVM WebAPI”. This takes care of delivering the required software for the challenge to your machine.

What is this, really?

This is a tiny system service (about 1MB) which provides the interface between the web browser and a Virtual Machine in your computer.

CernVM WebAPI installs VirtualBox

We have packed all the scientific software required to run the challenge into a compact, virtual computer. Virtualbox is a free, open-source software that runs this virtual computer.

Why is this necessary?
The scientific software that we use runs only on Linux. That’s why we packed our Linux distribution in a virtual machine so it can run on almost any operating system.

You are now in control

After all this software is installed on your computer, just click “Start” on the Challenge Dashboard, wait for the software to load and join the challenge! You can press “Stop” at any time. Note that closing the Challenge Dashboard does not stop the Virtual Machine!

What can I control?
You can define how much CPU and RAM you allocate to the project, by clicking on the gear icon next to the start button. Remember to click Apply!

Frequently Asked Questions

About the challenge

A: No! In fact, to avoid wasting energy, you should only participate while you are doing other stuff on your computer. For example trying out some of the other CERN-related public participation projects.
A: None! The virtual machine in your computer takes care of everything and sends us results periodically. It restarts automatically every time you restart your computer.
A: You can run anonymously if you like and your contributions will still be used and appreciated. But you may identify yourself with one or more of your social media ID's including: Facebook, Google+, Twitter or Live. To do this use the green button "Log-in and keep track of your progress" at any time. (In addition you can also identify yourself with your BOINC ID if you run the Test4Theory BOINC project).
A: If you are logged-in (see Q3 above), by clicking on "Progress details" all your contributions are displayed by CreditPiggy, your personal Piggy-bank.
A: You can get in touch with us using this Disqus Forum. Several particle physicists who will use the data you produce will be answering science questions you may have in the forum, and the challenge team is there to answer any technology questions.

About the software

A: The current prototype supports the following platforms :
  • MacOSX: 10.8 and later
  • Windows: XP SP3+ including Win7 and Win8
  • Linux: Ubuntu 13.0+ and SLC6 (Red Hat)
Browsers supported are :
  • Internet Explorer: 10+
  • Firefox: 11+
  • Chrome: 14+
  • Safari: 6+
  • Opera: 12.1+
  • SeaMonkey : 12.10.1+
A: When the Challenge Dashboard is open, and the virtual machine is running, you will see a Stop button at the bottom of the webpage. Click it to stop the virtual machine.
If you close the Challenge Dashboard, the virtual machine keeps running. You can always stop it by opening the Challenge Dashboard again. To do this, click the Start Computing button on this web page. The Challenge Dashboard will open. Then press the "Stop" button.
A: If the VM will not stop, even after doing the steps mentioned in Q2, it's probably because it is in a state called Guru Mediation. This means that VirtualBox encountered a critical problem and it paused the Virtual Machine in order for a "Guru" to have a look. The only way to get over this error is to kill the VBoxHeadless process and refresh the challenge website:
  • Windows
    • Start the Windows Task Manager
    • Locate the "VBoxHeadless.exe" process and click "End process"
  • Linux
    • Open a terminal
    • Assuming that you are not running any other Virtual Machine in your computer, type:
      killall VBoxHeadless
      and hit enter.
  • MacOSX
    • Close the challenge and WebAPI websites
    • Open the "Activity Monitor" application from the Utilities
    • Locate the "VBoxHeadless" process and double-click to open the details. If it does'nt quit, click "Force Quit".
    • Now open the challenge website and click Start Computing. The VM should start running again.
In all the above cases, If you are still encountering errors, destroy your Virtual Machine using the trash icon at the bottom of the configuration panel and then refresh the interface. To open this panel, click on the gear symbol at the bottom of the Challenge Dashboard. If the VM still doesn’t work after removing it and restarting, then remove it again, restart your computer, and try again. In certain rare cases, you may need to restart your computer a second time. If none of the above works for you, contact us through the forum or via with details of what is going wrong.
A: You need to force a restart of the running process cernvm-webapi as follows :
    • Windows:
      • Start the Windows Task Manager
      • Locate the "cernvm-webapi.exe" process and click "End process"
      • Open the run prompt (WinKey + R), paste the following and hit enter :
         ”C:\Program Files (x86)\CERN\CernVMWebAPI\cernvm-webapi.exe" service 
    • Linux:
      • Open a terminal
      • Type the following command and hit enter
         killall cernvm-webapi  
      • Type the following command and hit enter
         cernvm-webapi &  
    • Max OSX:
      • Open a terminal
      • Type the following command and hit enter
         killall cernvm-webapi  
      • The process will restart automatically… alternatively :
        • Open the "Activity Monitor" application from the Utilities
        • Locate the "cernvm-webapi" process, double-click to open the details, and click “Quit”. If it doesn’t quit, click “Force Quit”
A: To uninstall the app cernvm-webapi, follow the following procedures for the respective platforms:
    • Windows:  There is an uninstall link on the start menu
    • Mac OSX:
      • start a line-command terminal by opening Finder, opening the folder Utilities and clicking on Terminal, then write the following command and press Return(Enter):
         launchctl unload ~/Library/LaunchAgents/cern.cernvm.webapi.service.plist 
      • Then you can drag the CernVM WebAPI from the applications to the trash can.
    • Linux (Ubuntu)
       sudo apt-get remove cernvm-webapi 
    • Linux (SLC6 Red Hat)
       sudo yum remove cernvm-webapi 

    Residual Files
    The application keeps cache and other files required for normal operaion in a folder in the user's directory. If you want to fully uninstall the remaining files too, you should remove the following directory:
    • Windows: %appdata%/CernVM/WebAPI
    • Linux: ~/.cernvm/WebAPI
    • MacOSX: ~/Library/Application Support/CernVM/WebAPI
A: The only data about you that we keep on our server is a unique identifier for your computer, which we use to attribute your contributions, and your login username, but not the password.

We are using Google Analytics on the Computing Challenge and Web API pages, in order to gather detailed statistics about the website's traffic and the system's behavior. This information allows us to evaluate our technology, and continue improving it. In particular, we are curious to discover where people may get stuck with the instructions, and what other projects they may click through to, from this site.

This data is being gathered for research purposes in the Citizen Cyberlab project, where we’re trying to understand what people learn about science from participating in such initiatives, and how we might improve the learning experience in future. According to the Google Analytics terms of service, we do not track, collect or upload any data that personally identifies an individual (such as name or email).

A: Yes, just make sure you login with the same account everywhere, so you can aggregate your results.
  • This website is provided for information purposes only. The EU project Citizen Cyberlab makes every effort to ensure that the information is accurate and up-to-date.
  • Volunteer computing is an established approach with a long track-record of millions of users. The software you are downloading has been used on a wide range of computers by thousands of volunteers in the past. However, neither Citizen Cyberlab nor CERN makes any warranties as to the quality of the software, nor its suitability for any particular purpose, nor are Citizen Cyberlab and CERN liable for any damages whatsoever arising out of, or in connection with, the use of the site, or the downloaded software.
  • You agree to use this site and associated software only for lawful purposes, and in a manner that does not infringe the rights of, or restrict or inhibit the use and enjoyment of this site by, any third party. Every effort will be made to ensure a continuous service of this site and the associated software, but neither Citizen Cyberlab nor cannot guarantee that the service will be uninterrupted or error-free.

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