CMS Open Data Workshop 2021

CERN (Virtual)


Jul 19-22, 2021

2:30 pm - 6:40 pm (CET)

Instructors: Matt Bellis, Edgar Carrera Jarrin, Julie Hogan, Clemens Lange, Kati Lassila-Perini

Helpers: Marcelo Anda, Sid Boros, Anniina Kinnunen, Sarah Markham, Nick Pervan, Andro Petkovic, Farrah Simpson, Julian Westerlund

General Information

Since 2014, the CMS Collaboration has pioneered the release of LHC research quality data for public use by making a significant amount of these data accessible through the CERN Open Data portal. In 2020, the collaboration initiated a first-of-its-kind CMS Open Data Workshop where theorists, phenomenologists, and other interested researchers can learn more about how to interact with and analyze these vast datasets. This is the second version of that workshop and should benefit both new participants and attendees of the first iteration. The workshop aims to bridge the technical gap that usually exists between the scientific creativity of an external analyst and the nuts-and-bolts details of a full analysis with CMS open data. All exercises will be hands-on and participants should be prepared to dive into the data right away. A set of pre-exercises and assignments are provided and required for participants so that they can make the most of the workshop. Time will also be spent brainstorming with attendees about how the entire process of accessing and analyzing the data could be made more useful for the broader HEP community.

Please visit the official Indico site for the workshop.

Who: This workshop is primarily aimed at students and scientists with prior knowledge of collider physics and a deep interest in learning the works and arts of conducting experimental analysis using CMS Open Data.

Where: This training will take place online. The instructors will provide you with the information you will need to connect to this meeting.

When: Jul 19-22, 2021. Add to your Google Calendar. [Central European Time (CET)].

Requirements: Participants must bring a laptop with a Mac, Linux, or Windows operating system (not a tablet, Chromebook, etc.) that they have administrative privileges on. They should have a working virtual machine or Docker container environment as listed in the pre-exercises section.

Accessibility: We are dedicated to providing a positive and accessible learning environment for all. Please notify the instructors in advance of the workshop if you require any accommodations or if there is anything we can do to make this workshop more accessible to you.

Contact: Please email for more information.

Code of Conduct

All workshop participants are expected to follow the CERN Code of Conduct.


All times are in CET (Central European Time)
Help is available through our Mattermost channel and/or the CMS Open Data Forum.


(Mandatory exercises must be completed before the start of the workshop)
(Submission of work assignments is required as explained in the Orientation below)
Mandatory 5 min Orientation (General guidance)
Optional (external lesson)The Unix Shell
Optional (external lesson)Version Control with Git
Optional (external lesson)Programming with Python
Mandatory 2hVirtual Machine or Docker container setup for CMS Open Data (General guidance)
Mandatory 2.5hC++ and ROOT basics (Analysis flow)
Mandatory 1hIntro to physics objects (Basic physics objects)
Mandatory 2hCMSSW fundamentals (Basic physics objects)
Mandatory 1.25hTrigger essentials (Basic physics objects)


14:30-15:10Welcome and Intro (General guidance)Kati Lassila-Perini
15:10-15:55Intro/demo (Datasets and access)Matt Bellis
16:10-16:50Hands-on (Datasets and access)Matt Bellis
16:50-17:35Demo/Q's (Basic physics objects)Julie Hogan
17:50-18:30Hands-on (Basic physics objects)Julie Hogan
OfflineChallenge (Datasets and access)
OfflinePrep-work (Advanced physics objects)


14:30-15:10Solution/Q's (Datasets and access)Matt Bellis
15:10-15:55Challenge (Basic physics objects)Julie Hogan
16:10-16:50Solution/Q's (Basic physics objects)Julie Hogan
16:50-17:35Demo/Q's (Advanced physics objects)Julie Hogan
17:50-18:30Hands-on (Advanced physics objects)Julie Hogan
OfflineChallenge (Advanced physics objects)
OfflinePrep-work (Analysis flow)
OfflinePrep-work (Cloud computing)


14:30-15:10Solution (Advanced physics objects)Julie Hogan
15:10-15:55Demo/Q's (Analysis flow)Edgar Carrera
16:10-16:50Hands-on (Analysis flow)Edgar Carrera
16:50-17:35Hands-on (Analysis flow)Edgar Carrera
17:50-18:30Demo/Q's (Cloud computing)Edgar Carrera,
Kati Lassila-Perini,
Clemens Lange
OfflineChallenge (Analysis flow)


14:30-15:10Solution/Q's (Analysis flow)Edgar Carrera
15:10-15:55Hands on (Cloud computing)Edgar Carrera,
Kati Lassila-Perini,
Clemens Lange
16:10-16:50Hands on (Cloud computing)Edgar Carrera,
Kati Lassila-Perini,
Clemens Lange
16:50-17:35Wrap-up discussionEveryone