Where to ask questions

Last update: 14 Nov 2022 [History] [Edit]

Asking questions about software will likely be a frequent part of your work in ATLAS. The following are some of the few channels dedicated to answering users’ questions.

Mailing lists

The dedicated mailing lists are probably the best way to get a fast response from experts. There are dedicated lists for different topics. Don’t be shy about asking “beginner” questions, that is the purpose of these channels.

A good place to check before asking your question is the email archives for each group. These can be found at https://groups.cern.ch/Pages/atlas.aspx.

What to include

When contacting the mailing lists please be as detailed as possible. When asking for software help, you will never be accused of providing too much detail.

Include things such as:

  • A minimal example that reproduces the problem
  • Log files
  • Links to grid jobs
  • Exact command(s) used
  • Your source code (via GitLab)
  • Input files

If log files or input files are large, share them via CERNBox.


Mattermost is a team communication service very similar in functionality to Slack. This is supported at CERN and can be accessed by the Mattermost App or through the CERN Mattermost page. You should have access to the service by default if you have a CERN account.

CERN Mattermost has several “teams” you can join, each of which has multiple channels. A good place for software questions is the atlassoftware team.


Discourse is a question and answer forum very similar to a Stack Exchange platform. As users ask questions here the knowledge base contained will grow and become more useful.

There is a dedicated ATLAS Talk server as well as a general CERN server.

CERN Service Portal

The CERN Service Portal is the place to visit for all questions and problems with CERN infrastructure and services. These include things like account management, CERNBox, service outages, security, etc.


The CERN Code of Conduct

Please remember, the CERN Code of Conduct applies to all of these communication channels.