Upgrade of the CMS resistive plate chambers for the high luminosity LHC

During the upcoming High Luminosity phase of the Large Hadron Collider (HL-LHC), the integrated luminosity of the accelerator will increase to 3000 fb−1. The expected experimental conditions in that period in terms of background rates, event pileup, and the probable aging of the current detectors present a challenge for all the existing experiments at the LHC, including the Compact Muon Solenoid (CMS) experiment. To ensure a highly performing muon system for this period, several upgrades of the Resistive Plate Chamber (RPC) system of the CMS are currently being implemented. These include the replacement of the readout system for the present system, and the installation of two new RPC stations with improved chamber and front-end electronics designs. The current overall status of this CMS RPC upgrade project is presented.

Unified Phase Field Theory Based on the Interaction of Positive and Negative Magnetic poles and Analysis of ATLAS, CMS Experiment at the LHC

This article assumes that the elementary particle is a magnetic poles field formed by the interaction of positive and negative magnetic pole, believes that the gravity, the electromagnetic force, the strong force and the weak force are all produced by the interaction of positive and negative magnetic pole. The collision of the high-energy elementary particles appears as a strong force, and the decay of the high-energy elementary particles appears as a weak force, the cohesive force of the high-energy elementary particle magnetic pole field (the gravitational field) to its magnetic pole is the gravity, and the spin force of the high-energy elementary particle magnetic pole field in the external field (the gravitational field) is the electromagnetic force. This article discuss the high-energy proton-antiproton collision experiment based on the interaction of positive and negative magnetic pole, reveals the production mechanism of the protonium, tauium, muonium, positronium, three generation of leptons and neutrinos, and final state. This article explains unify of the strong force, weak force, electromagnetic force and gravity with unified phase field theory, and tested with the data of ATLAS and CMS experiment at the LHC. The data of ATLAS and CMS experiment at the LHC is completely consistent with the calculated data of the phase field curvature tensor equation; Differential geometric variables are covariant with physical variables; The Lagrangian function of Einstein's mass-energy equation, the Lagrangian function of Schrodinger particle differential motion wave function based on the theory of relativity, the Lagrangian density of Young-Mills gauge field equation, and the planets phase difference momentum-energy tensor of the curvature tensor equation is completely consistent in the high-energy proton-antiproton collision experiment. These fully prove that the unified phase field theory is more in line with the physical reality of the high-energy proton-antiproton collision experiment.

Beam test results of silicon sensor module prototypes for the Phase-2 Upgrade of the CMS Outer Tracker

The start of the High-Luminosity LHC (HL-LHC) in 2027 requires upgrades to the Compact Muon Solenoid (CMS) experiment. In the scope of the upgrade program the complete silicon tracking detector will be replaced. The new CMS Tracker will be equipped with silicon pixel detectors in the inner layers closest to the interaction point and silicon strip detectors in the outer layers. The new CMS Outer Tracker will consist of two different kinds of detector modules called PS and 2S modules. Each module will be made of two parallel silicon sensors (a macro-pixel sensor and a strip sensor for the PS modules and two strip sensors for the 2S modules). Combining the hit information of both sensor layers, it is possible to estimate the transverse momentum of particles in the magnetic field of 3.8 T at the full bunch-crossing rate of 40 MHz directly on the module. This information will be used as an input for the first trigger stage of CMS. It is necessary to validate the Outer Tracker module functionality before installing the modules in the CMS experiment. Besides laboratory-based tests several 2S module prototypes have been studied at test beam facilities at CERN, DESY and FNAL. This article concentrates on the beam tests at DESY during which the functionality of the module concept was investigated using the full final readout chain for the first time. Additionally the performance of a 2S module assembled with irradiated sensors was studied. By choosing an irradiation fluence expected for 2S modules at the end of HL-LHC operation, it was possible to investigate the particle detection efficiency and study the trigger capabilities of the module at the beginning and end of the runtime of the CMS experiment.

Selection of the silicon sensor thickness for the Phase-2 upgrade of the CMS Outer Tracker

During the operation of the CMS experiment at the High-Luminosity LHC the silicon sensors of the Phase-2 Outer Tracker will be exposed to radiation levels that could potentially deteriorate their performance. Previous studies had determined that planar float zone silicon with n-doped strips on a p-doped substrate was preferred over p-doped strips on an n-doped substrate. The last step in evaluating the optimal design for the mass production of about 200 m2 of silicon sensors was to compare sensors of baseline thickness (about 300 μm) to thinned sensors (about 240 μm), which promised several benefits at high radiation levels because of the higher electric fields at the same bias voltage. This study provides a direct comparison of these two thicknesses in terms of sensor characteristics as well as charge collection and hit efficiency for fluences up to 1.5 × 1015 neq/cm2. The measurement results demonstrate that sensors with about 300 μm thickness will ensure excellent tracking performance even at the highest considered fluence levels expected for the Phase-2 Outer Tracker.