In 2004, Theory Division (TH) and Experimental Physics Division (EP) merged to form Physics Department (PH). The PH Department carries out the basic research in the field of experimental and theoretical particle physics.

The Department is sub-divided into two units :

• The groups of the Experimental Physics unit are active in the domains of detector technologies, including mechanics, electronics and experiment related computing. They participate in the construction and running of experiments and in the physics analysis. They provide technical, administrative and logistics support for experimental teams performing experiments at CERN's accelerator facilities.
• The objective of the Theory unit is to develop new theoretical ideas aimed at understanding the fundamental constituents and forces of nature. To develop their relevance for the experimental programme of CERN and conversely to take full advantage of the stimulating environment of a large Laboratory. To contribute to the general scientific culture at CERN through active participation in the various training programmes and promotion of scientific events on site.

In 2009 the CERN management changed and adopted a new organizational structure. Physics (PH) and Information Technology (IT) Departments were grouped into the Research & Scientific Computing Sector.

• Theory Unit
• Administraion & General Services
• Detector Technology
• Electronic Systems for experiments
• Software Development for experiments
• ALICE, ATLAS, CMS, LHCb, TOTEM Teams
• Non-LHC programmes