The trigger system of the CMS experiment and its upgrade
by
DrManfred Jeitler(HEPHY Vienna)
→
Europe/Rome
131 (INFN edificio C)
131
INFN edificio C
Description
The CMS experiment at CERN's Large Hadron Collider (LHC) in Geneva, Switzerland, has to cope with high collision rates and big data volumes. This is only possible by using a powerful trigger system, which in the case of CMS consists of a hardware-based Level-1 trigger and a High-Level Trigger based on a computer farm.
This system has been used successfully since LHC started operation but the higher event rates due to the increase in collision energy and luminosity have made an upgrade indispensable. The upgrade of the Level-1 trigger makes it possible to use more selective trigger conditions at the hardware level and improve the reliability of the system. Many trigger subsystems use FPGAs (Field Programmable Gate Arrays) in the electronics and are benefitting from developments in this technology, allowing developers to place much more logic into a single FPGA chip, thus reducing the number of chips, electronic boards and interconnections and in this way improving reliability. A number of subsystems are switching from the old VME bus to the new microTCA crate standard. Using similar approaches, identical modules and common software wherever possible reduces costs and manpower requirements and improves the serviceability of the whole trigger system. The computer-farm based High-Level Trigger is not only being extended by using increasing numbers of more powerful PCs but also the software has been improved, making it easier to maintain and resulting in a better efficiency of the whole system.