Compact Muon Solenoid Trigger Research Articles

The CMS Calorimeter Trigger for LHC Run II

The Compact Muon Solenoid (CMS) experiment has implemented a sophisticated two-level online selection system that achieves a rejection factor of nearly 105. During Run II, the LHC has increased its centre-of-mass energy up to 13 TeV and will progressively reach an instantaneous luminosity of 2×1034cm−2s−1. In order to guarantee a successful and ambitious physics programme under this intense environment, the CMS Trigger and Data acquisition (DAQ) system has been upgraded. A novel concept for the L1 calorimeter trigger is introduced: the Time Multiplexed Trigger (TMT). In this design, which is similar to the CMS DAQ or High Level Trigger (HLT) architecture, nine main processors each receive all of the calorimeter data from an entire event via 18 pre-processors. The advantage of the TMT architecture is that a global view and full granularity of the calorimeters can be exploited by complex algorithms. The goal is to maintain the current thresholds for calorimeter objects and improve the performance for their selection. The introduction of new triggers based on the combination of calorimeter objects is also foreseen.

The CMS Level-1 trigger system for LHC Run II

The Compact Muon Solenoid (CMS) experiment implements a sophisticated two-level online selection system that achieves a rejection factor of nearly 105. During Run II, the LHC has increased the centre-of-mass energy of proton-proton collisions up to 13 TeV and may progressively reach an instantaneous luminosity of 2×1034 cm−2 s−1 or higher. In order to guarantee a successful and ambitious physics programme under this intense environment, the CMS Trigger and Data acquisition system has been upgraded. The upgraded CMS Level-1 (L1) trigger benefits from the recent μTCA technology and is designed to maintain the performance under high instantaneous luminosity conditions. More sophisticated, innovative algorithms are now the core of the first decision layer of CMS: this drastically reduces the trigger rate and improves the trigger efficiency for a wide variety of physics processes. In this document, we present the overall architecture of the upgraded Level-1 trigger system. The performance of single object triggers, measured on collision data recorded during the 2016 running period, are also summarised.

Triggering on electrons, jets and tau leptons with the CMS upgraded calorimeter trigger for the LHC RUN II

The Compact Muon Solenoid (CMS) experiment has implemented a sophisticated two-level online selection system that achieves a rejection factor of nearly 105. During Run II, the LHC will increase its centre-of-mass energy up to 13 TeV and progressively reach an instantaneous luminosity of 2 × 1034 cm−2 s−1. In order to guarantee a successful and ambitious physics programme under this intense environment, the CMS Trigger and Data acquisition (DAQ) system has been upgraded. A novel concept for the L1 calorimeter trigger is introduced: the Time Multiplexed Trigger (TMT) . In this design, nine main processors receive each all of the calorimeter data from an entire event provided by 18 preprocessors. This design is not different from that of the CMS DAQ and HLT systems. The advantage of the TMT architecture is that a global view and full granularity of the calorimeters can be exploited by sophisticated algorithms. The goal is to maintain the current thresholds for calorimeter objects and improve the performance for their selection. The performance of these algorithms will be demonstrated, both in terms of efficiency and rate reduction. The callenging aspects of the pile-up mitigation and firmware design will be presented.

Data-driven performance evaluation method for CMS RPC trigger system using 2011 data at LHC

The compact muon solenoid (CMS) is one of the four experiments which is getting and analysing the results of the collision of protons at LHC. The CMS trigger system is divided into two stages, the level-1 trigger and high-level triggers, to handle the large stream of data produced in collision. The information transmitted from the three muon subsystems (DT, CSC and RPC) are collected by the Global Muon Trigger (GMT) Board and merged. A method for evaluating the RPC system trigger efficiency with data from pp collision was developed using the features of GMT. The results of the study with the real data of 2011 are shown and discussed here along with the comparison of Monte Carlo results.