Daniel Teyssier

CMS is a general purpose experiment, designed to study the physics of pp collisions at 14 TeV at the Large Hadron Collider (LHC). It currently involves more than 2000 physicists from more than 150 institutes and 37 countries. The LHC will provide extraordinary opportunities for particle physics based on its unprecedented collision energy and luminosity when it begins operation in 2007.

During summer 2006 a fraction of the CMS silicon strip tracker was operated in a comprehensive slice test called the Magnet Test and Cosmic Challenge (MTCC). At the MTCC, cosmic rays detected in the muon chambers were used to trigger the readout of all CMS sub-detectors in the general data acquisition system and in the presence of the 4 T magnetic field produced by the CMS superconducting solenoid. This document describes the operation of the Tracker hardware and software prior, during and after data taking. The performance of the detector as resulting from the MTCC data analysis is also presented.

In March 2007 the assembly of the Silicon Strip Tracker was completed at the Tracker Integration Facility at CERN. Nearly 15% of the detector was instrumented using cables, fiber optics, power supplies, and electronics intended for the operation at the LHC. A local chiller was used to circulate the coolant for low temperature operation. In order to understand the efficiency and alignment of the strip tracker modules, a cosmic ray trigger was implemented. From March through July 4.5 million triggers were recorded. This period, referred to as the Sector Test, provided practical experience with the operation of the Tracker, especially safety, data acquisition, power, and cooling systems. This paper describes the performance of the strip system during the Sector Test, which consisted of five distinct periods defined by the coolant temperature. Significant emphasis is placed on comparisons between the data and results from Monte Carlo studies.

The results of the CMS tracker alignment analysis are presented using the data from cosmic tracks, optical survey information, and the laser alignment system at the Tracker Integration Facility at CERN. During several months of operation in the spring and summer of 2007, about five million cosmic track events were collected with a partially active CMS Tracker. This allowed us to perform first alignment of the active silicon modules with the cosmic tracks using three different statistical approaches; validate the survey and laser alignment system performance; and test the stability of Tracker structures under various stresses and temperatures ranging from +15 °C to −15 °C. Comparison with simulation shows that the achieved alignment precision in the barrel part of the tracker leads to residual distributions similar to those obtained with a random misalignment of 50 (80) μm RMS in the outer (inner) part of the barrel.

The barrel region of the Compact Muon Solenoid (CMS) experiment at the Large Hadron Collider is instrumented with Drift Tube (DT) detectors. This paper describes in full details the calibration of the DT hit reconstruction algorithm. After inter-channel synchronization has been verified through the appropriate hardware procedure, the time pedestals are extracted directly from the distribution of the recorded times. Further corrections for time-of-flight and time of signal propagation are applied as soon as the three-dimensional hit position within the DT chamber is known. The different effects of the time pedestal miscalibration on the two main hit reconstruction algorithms are shown. The drift velocity calibration algorithm is based on the meantimer technique. Different meantimer relations for different track angles and patterns of hit cells are used. This algorithm can also be used to determine the uncertainty on the reconstructed hit position.

We present the results and prospects for searches beyond the Standard Model (SM) at the LHC by the ATLAS and CMS collaborations. The minimal supersymmetric extension of the SM has been investigated in various configurations and lower limits are set on the s-particle masses. The searches for other scenarios of physics beyond the SM are also presented and lower limits on the mass scale are derived in a large variety of models (new heavy gauge bosons, extra-dimensions, compositeness or dark matter). The prospects for physics using 300 /fb and 3000 /fb of data at the high luminosity LHC are also shown.

The CMS muon barrel drift tubes system has been recently fully installed and commissioned in the experiment. The performance and the current status of the detector are briefly presented and discussed.

The drift velocity is a key parameter of drift chambers. Its value depends on several parameters: electric field, pressure, temperature, gas mixture, and contamination, for example, by ambient air. A dedicated Velocity Drift Chamber (VDC) with 1-L volume has been built at the III. Phys. Institute A, RWTH Aachen, in order to monitor the drift velocity of all CMS barrel muon Drift Tube chambers. A system of six VDCs was installed at CMS and has been running since January 2011. We present the VDC monitoring system, its principle of operation, and measurements performed.

General two Higgs doublet models allow for five scalar bosons, three of which being neutral. No signal is found in the data collected by the L3 detector in e + e - collisions at 189 – 202 GeV center-of-mass energies. Limits are set on the couplings of the h and A Higgs bosons to the Z boson.

The ETscope detector designed for the ULTRA experiment is a small array made of 7 particle detection stations. Operating simultaneously with an optical telescope it detects the Extensive Air Showers in coincidence with the ˇ Cerenkov light, diffused by the impact on the ground. The main goal of the detector is the characterization of the impinging shower by the measurement of size and arrival direction. These informations, together with the UV light measurement and an accurate MC simulation, will allow the determination of the diffusing features of the ground. Since it must be placed on different surfaces including sea, it has been optimized as portable, floating and waterproof detector. First test has been performed during October 2002 at Mont-Cenis in the Alps region, at the France-Italy border. Detector performances and preliminary results will be discussed here. 1. The ETscope Detector The ETscope array of the ULTRA project [1] was located at Mont-Cenis site (1970 meters a.s.l, 45.3 North, 6.9 East) at an equivalent atmospheric depth of 805 g/cm 2 . In the used configuration 3 stations were placed at vertexes of a triangle, each one 23 m from the central fourth station (see fig. 2.). Each station includes a plastic NE102A scintillator 80 × 80 cm 2 wide and 4 cm thick seen by two photomultipliers XP3462. They are contained in a pyramidal shape box made with thin stainless steel, coated with white diffusing paint and placed in a 1 m 3 PVC container. A standard NIM and CAMAC electronics, controlled by a PC under LabView software, is used for data read-out. PMT calibration and gain stability are obtained through the measurement of single muon spectra from which the Vertical Equivalent Muon charge (VEM) is defined. Therefore the measured analog signal of each station converted in VEM units gives the particle density yield. A 3-fold, 150 ns coincidence between 3 external stations is required to trigger the DAQ. The hardware trigger threshold is set to 0.3 VEM/module and the dynamic range allows to measure particle densities up to 40 VEM.

The CMS experiment at the LHC collected in 2011 around 5 /fb of integrated luminosity at 7 TeV center-of-mass energy. The CMS detector has shown an excellent data taking efficiency. The global CMS and several subdetector performances will be sented. The goal of the 2012 operations is to collect again 5 /fb by the end of June finally more than 15 /fb at the end of 2012, with a new center-of-mass energy at 8 TeV and higher luminosity. The CMS detector should cope with these new conditions and first results from 2012 data will be given.

We present the results and prospects for searches beyond the Standard Model (SM) at the LHC by the ATLAS and CMS collaborations. The minimal supersymmetric extension of the SM has been investigated in various configurations and lower limits are set on the s-particle masses. The searches for other scenarios of physics beyond the SM are also presented and lower limits on the mass scale are derived in a large variety of models (new heavy gauge bosons, extra-dimensions, compositeness or dark matter). The prospects for physics using 300 /fb and 3000 /fb of data at the high luminosity LHC are also shown.

The CMS muon system is taking cosmic data since 2006 and is using them to study the performance of the three different detector technologies and triggers (drift tube, cathode strip chambers and resistive plate chambers). The muon system is described placing emphasis on the software tools that were developed and used to take data and to study, online and offline, the performance of the muon system. The results obtained analyzing up to 300 millions of cosmics acquired with the CMS detector will be described.

The results of the CMS tracker alignment analysis are presented using the data from cosmic tracks, optical survey information, and the laser alignment system at the Tracker Integration Facility at CERN. During several months of operation in the spring and summer of 2007, about five million cosmic track events were collected with a partially active CMS Tracker. This allowed us to perform first alignment of the active silicon modules with the cosmic tracks using three different statistical approaches; validate the survey and laser alignment system performance; and test the stability of Tracker structures under various stresses and temperatures ranging from $+15^circ$C to $-15^circ$C. Comparison with simulation shows that the achieved alignment precision in the barrel part of the tracker leads to residual distributions similar to those obtained with a random misalignment of $50$ ($80$)~$mu$m in the outer (inner) part of the barrel.

New studies of the CMS collaboration are presented on the sensitivity to searches for non‐standard signatures of particular SUSY scenarios. These signatures include non‐pointing photons as well as pairs of prompt photons as expected GMSB SUSY models, as well as heavy stable charged particles produced in split supersymmetry models, long lived staus from GMSB SUSY and long lived stops in other SUSY scenarios. Detailed detector simulation is used for the study, and all relevant Standard Model background and detector effects that can mimic these special signatures are included. It is shown that with already with less than 100 pb−1 the CMS sensitivity will probe an interesting as yet by data unexplored parameter range of these models.

The ULTRA experiment [4] has been designed in the framework of the EUSO project to measure the reflected/diffused signal produced by the EAS impacting on the Earth surface. EUSO will detect the EECRs measuring the fluorescent light produced by the interaction with the Earth atmosphere. With this method, the particle track can be measured together with its relative depth, but not its absolute position. ˇ Cerenkov light associated to the EAS is emitted in a narrow cone and hits the Earth surface, being partially absorbed and partially diffused. This signal will give an absolute reference for the track, allowing the measurement of the shower maximum and making also easier the separation between neutrino and hadronic showers. Moreover, ˇ Cerenkov light can give an independent estimation of the shower energy if the reflectivity of the shower impinging surface is known. The ULTRA detector includes a UV optical device to collect the ˇ Cerenkov light diffused by various surfaces and an array of scintillators to detect, in coincidence, cosmic ray showers. First tests have been done last October in Mont-Cenis (France, 1970 m a.s.l.); next measurement campaign is

Cette these effectuee au sein du groupe Higgs de la collaboration L3 porte sur la recherche d'une signature Higgs, pour des energies dans le centre de masse comprises entre 192 et 209 GeV, constituant l'un des enjeux majeurs a LEP2. Elle consiste en une contribution aux analyses recherchant le boson de Higgs du Modele Standard, particulierement dans le canal jets plus energie manquante. L'etat final pour ce canal, note H_nu_nubar, est caracterise par la production d'une paire de quarks b issus du boson de Higgs, et d'une paire de neutrinos issus du boson Z, pour le processus dominant de Higgs-Strahlung. La limite inferieure observee, obtenue avec ce seul canal H_nu_nubar, est de 96 GeV a un niveau de confiance de 95%. De plus, les recherches de production de scalaires neutres sont developpees, dans les modeles generaux a deux doublets de Higgs de type II, au moyen d'une analyse dite independante de saveur. On presente aussi les recherches concernant le boson de Higgs invisible, ou le boson Z se desintegre en une paire de fermions et le boson de Higgs en particules indetectables. L'utilisation de ces derniers resultats permet de contraindre les parametres des modeles supersymetriques minimaux non-universels (sans unification de masse des jauginos).