The old Trigger home page, quite obsolete, can be accessed here.

The LHCb Trigger has three levels:

• Level-0, a hardware level reducing the rate to 1 MHz in 4 μs
• Level-1, a software level using selected data, reducing the rate to 40 kHz with about 1 ms processing time.
• HLT, a software level running on the whole event, with an output rate up to 2 kHz and 10 ms processing time.

Three projects (or sub-projects) are working together to provide the LHCb trigger.

• The L0 Project handles the hardware and software of the Level 0 trigger.
• The Reconstruction (sub-project of the Computing project) handles the tracking and PID reconstruction both for Level-1 and HLT.
• The Trigger Project handles the selection and monitoring algorithms, and optimize the working point of all triggers.