Search

The LHCb experiment at the LHC has collected more than 1 fb-1 of physics data during the first two years of operation at the LHC, reaching one of its most important milestones. This has allowed the experiment to already perform extensive world-class measurements in b and c-physics, in order to probe New Physics Beyond the Standard Model. In this paper, the status and excellent performance of the LHCb experiment are reviewed, focusing the attention on the most important aspects of the operation of the experiment. Moreover, several important physics results are highlighted together with their impact for the full physics program at the LHC. Finally, a description of the upgrade of the detector to collect more than 50 fb -1 starting in 2018 will be also given. [ABSTRACT FROM AUTHOR]

In this paper, a measurement of ? polarization in W? ?? decays is presented. It is measured from the energies of the decay products in hadronic ? decays with a single final state charged particle. The data, corresponding to an integrated luminosity of 24 pb, were collected by the ATLAS experiment at the Large Hadron Collider in 2010. The measured value of the ? polarization is ${P_{\tau}}= -1.06 \pm0.04\ (\mathrm{stat})\;^{+0.05}_{-0.07}\ (\mathrm{syst})$, in agreement with the Standard Model prediction, and is consistent with a physically allowed 95 % CL interval [?1,?0.91]. Measurements of ? polarization have not previously been made at hadron colliders. [ABSTRACT FROM AUTHOR]

The ALICE High Level Trigger comprises a large computing cluster, dedicated interfaces and software applications. It allows on-line event reconstruction of the full data stream of the ALICE experiment at up to 25 GByte/s. The commissioning campaign has passed an important phase since the startup of the Large Hadron Collider in November 2009. The system has been transferred into continuous operation with focus on the event reconstruction and first simple trigger applications. The paper reports for the first time on the achieved event reconstruction performance in the ALICE central barrel region. [ABSTRACT FROM PUBLISHER]

ALICE at the CERN LHC will investigate the physics of strongly interacting matter at extreme energy densities where the formation of the Quark Gluon Plasma is expected. Its properties can be studied from observations like the production of mesons with charm and beauty quarks. These signals have to be studied as a function of energy density, which is determined by the centrality of collisions. One of the physics observables that is closely related with the centrality of the collision is the number of spectator nucleons that can be measured by the Zero Degree Calorimeters (ZDC). Having a direct geometric interpretation allows to extract the impact parameter with minimal model assumptions. This paper describes the readout system of the ZDC. The ZDC readout consists of a VME system with a ZDC Readout Card, a VME Processor, Discriminators, a ZDC Trigger Card, scalers, QDCs and TDCs. The system was successfully tested during the 2009 ALICE data taking and is currently operational at the LHC. [ABSTRACT FROM PUBLISHER]

The Atlas muon spectrometer relies on Monitored Drift Tubes (MDTs) for track reconstruction in most regions. Expected count rates due to photons reach up to 1500 Hz/cm for the innermost MDTs. For a gas gain of 2middot104 this corresponds to an overall accumulated charge of up to 0.6 C/cm which the MDTs must be able to withstand in 10 years of LHC operation without a degradation in their performance. With the main MDT parameters and the design frozen and chamber production well under way the focus of present aging studies is on testing final Atlas chambers instead of using small, dedicated setups under very well controlled conditions as in the past. This paper summarizes the results of such a study performed at the CERN Gamma Irradiation Facility GIF, that aims to emulate LHC background conditions. One of the main goals was to evaluate the principle of gas recirculation and a prototype of the Atlas circulation system [ABSTRACT FROM PUBLISHER]

Abstract: The transition radiation tracker (TRT) is the outermost of the three sub-systems of the ATLAS inner detector at the Large Hadron Collider (LHC) at CERN. It is designed to combine the drift tube tracker with the transition radiation detector, providing an important contribution to the charged particles precise momentum measurement and particle (mainly electron) identification. The TRT consists of a barrel section at small pseudorapidity () and two separate end-cap partitions at large . The detector performance and its operational conditions were permanently monitored during all commissioning and data-taking stages using various software tools, one of which – TRTViewer – is described in the present paper. The TRTViewer is the dedicated program for monitoring the TRT raw data quality and detector performance at different hardware levels: individual straws, readout chips and electronic boards. The data analysis results can be presented on the event-by-event basis or in the form of color maps representing the operation parameters (efficiencies, timing, occupancy, etc.) according to the real geometrical position of the detector hardware elements. The paper describes the TRTViewer software package as the event displaying tool, raw data processor and histogram and operation parameters presenter, which works with the different sources of input information: raw data files, online monitoring histograms, offline analysis histograms and TRT DAQ Configuration database. The package proved to be one of the main instruments for the fast and effective TRT diagnostics during debugging and operation periods. [Copyright &y& Elsevier]

Abstract: For the experiments at the Large Hadron Collider at CERN the detectors in the vertex region and the tracking systems are very critical components for the success of the projects. Due to the harsh environment at the high intensity hadron collider these detectors are also the most challenging to construct. The design of the experiments started about 25 years ago. At this time silicon detectors as particle detectors for high energy physics experiments were still in their infancy. But, because of the huge progress made in developing this technology all LHC experiments finally employed silicon detectors and some experiments even constructed very large silicon systems. The LHC experiments went into operation in 2009, and after two years of operation the performance of the detectors can now be evaluated. This paper gives an overview of the different silicon detector systems at LHC and summarizes the installed silicon detector types and dimensions. [Copyright &y& Elsevier]

Abstract: TheATLASPixel Detectoristhe innermost detectoroftheATLASexperimentattheLarge Hadron CollideratCERN, providing high-resolution measurements of charged particle tracks in the high radiation environment close to the collision region. This capability is vital for the identification and measurement of proper decay times of long-lived particles such as b-hadrons, and thus vital for theATLASphysics program. The detector provides hermetic coverage with three cylindrical layers and three layers of forward and backward pixel detectors. It consists of approximately 80 million pixels that are individually read out via chipsbump-bonded to 1744 n-on-n silicon substrates. In this paper results from the successful operation of the Pixel Detector at the LHC will be presented, including calibration procedures, timing optimization and detector performance. The detector performance is excellent: approximately 97% of the pixels are operational, noise occupancyand hit efficiency exceed the design specification, and a good alignment allows high quality track resolution. [Copyright &y& Elsevier]

Abstract: High energy physics detectors span a wide range of applications with greatly differing requirements. Although the detector configurations are very different, the application of only a few basic signal acquisition principles is required. The LHC required novel designs, but built on a wide range of previous developments that had been completed for other experiments. The high luminosity drove up the event rates, but multiple interactions per bunch crossing also made occupancy a major challenge. The large scale of detector subsystems imposed efficient designs where cost was a major consideration, but the difficulty of accessing detector components added reliability to the list of more severe requirements. Radiation damage, especially in the inner detectors, added additional crucial constraints. This paper will discuss electronics requirements, the configurations of major LHC detectors, and the readout systems. After a discussion of front-end implementations and radiation effects, systems with extreme performance requirements are described in more detail, i.e. silicon strip and pixel systems. [Copyright &y& Elsevier]

Abstract: Multipurpose detectors are used widely in high energy physics experiments. They work on the same set of fundamental operating principles although specialized in their design goals and detection features. The Large Hadron Collider (LHC) has four major experiments exploiting these techniques, and in the future the International Linear Collider (ILC) will employ the detectors that are being designed presently and will utilize the particle-flow algorithms in order to obtain the desired dijet mass resolution. A complete understanding of the above mentioned detectors, their designs and the particle detection mechanisms can enable the prediction of the most desirable attributes of an ideal particle-detector design. In this introductory paper, we highlight the techniques used for radiation detection particularly at LHC, and the articles that follow in this volume. [Copyright &y& Elsevier]

Abstract: The Pixel Detector is the innermost part of the ATLAS experiment tracking device at the Large Hadron Collider, and plays a key role in the reconstruction of the primary vertices from the collisions and secondary vertices produced by short-lived particles. To cope with the high level of radiation produced during the collider operation, it is planned to add to the present three layers of silicon pixel sensors which constitute the Pixel Detector, an additional layer (Insertable B-Layer, or IBL) of sensors. 3D silicon sensors are one of the technologies which are under study for the IBL. 3D silicon technology is an innovative combination of very-large-scale integration and Micro-Electro-Mechanical-Systems where electrodes are fabricated inside the silicon bulk instead of being implanted on the wafer surfaces. 3D sensors, with electrodes fully or partially penetrating the silicon substrate, are currently fabricated at different processing facilities in Europe and USA. This paper reports on the 2010 June beam test results for irradiated 3D devices produced at FBK (Trento, Italy). The performance of these devices, all bump-bonded with the ATLAS pixel FE-I3 read-out chip, is compared to that observed before irradiation in a previous beam test. [Copyright &y& Elsevier]

Abstract: A new ATLAS pixel chip FE-I4 is being developed for use in upgraded LHC luminosity environments, including the near-term Insertable B-Layer (IBL) upgrade. FE-I4 is designed in a 130nm CMOS technology, presenting advantages in terms of radiation tolerance and digital logic density compared to the CMOS technology used for the current ATLAS pixel IC, FE-I3. The FE-I4 architecture is based on an array of 80×336 pixels, each , consisting of analog and digital sections. In the summer 2010, a first full scale prototype FE-I4A was submitted for an engineering run. This IC features the full scale pixel array as well as the complex periphery of the future full-size FE-I4. The FE-I4A contains also various extra test features which should prove very useful for the chip characterization, but deviate from the needs for standard operation of the final FE-I4 for IBL. In this paper, focus will be brought to the various features implemented in the FE-I4A submission, while also underlining the main differences between the FE-I4A IC and the final FE-I4 as envisioned for IBL. [Copyright &y& Elsevier]

Abstract: This paper gives a detailed description of the acquisition and trigger electronics especially designed for the V0 detector of ALICE at LHC. A short presentation of the detector itself is given before the description of the Front End Electronics (FEE) system, which is completely embedded within the LHC environment as far as acquisition (DAQ), trigger (CTP), and detector control (DCS) are concerned. It is able to detect on-line coincident events and to achieve charge (with a precision of 0.6 pC) and time measurements (with a precision of 100ps). It deploys quite a simple architecture. It is however totally programmable and fully non-standard in discriminating events coming from Beam–Beam interaction and Beam-Gas background. Finally, raw data collected from the first LHC colliding beams illustrate the performance of the system. [ABSTRACT FROM AUTHOR]

Abstract: The CMS pixel detector was installed in July 2008 in the innermost region of CMS. It consists of 66 million pixels of by size over 3 barrel layers and 2 forward disks. The pixel system has been successfully commissioned. Over 80K muon tracks were taken during the CMS cosmic runs and the detector is ready for the first physics run. The pixel detector, so close to the interaction point, will be exposed to a very high radiation dose. The estimation is that the first barrel layer, located at 4.3cm from the beam pipe, after 3 years of LHC running at full luminosity will become inefficient for position reconstruction. For this reason, a susbstitution of a new pixel detector in 2014 has been already scheduled. At the same time an LHC luminosity upgrade is also planned. While a simple rebuild of the current detector could be done, the expectation is to design a new one, optimized for higher luminosity. This paper describes the present system and its performance as well as possible solutions for the upgrade. [ABSTRACT FROM AUTHOR]

Abstract: The Fibre Active Scintillator Target (FAST) experiment is a novel imaging particle detector currently operating in a high-intensity π+ beam at the Paul Scherrer Institute (PSI), Villigen, Switzerland. The detector is designed to perform a high precision measurement of the μ+ lifetime, in order to determine the Fermi constant, G f, to 1ppm precision. A dedicated second level (LV2) hardware trigger system has been developed for the experiment. It performs an online analysis of the π/μ decay chain by identifying the stopping position of each beam particle and detecting the subsequent appearance of the muon. The LV2 trigger then records the muon stop pixel and selectively triggers the Time-to-Digital Converters (TDCs) in the vicinity. A detailed description of the trigger system is presented in this paper. [Copyright &y& Elsevier]

Abstract: A complementary physics to the LHC subjects comes from the neutrino sector which has already opened a window beyond the standard model. Neutrino oscillations have already proved that neutrinos have non zero masses. But, neutrino nature and absolute mass scale are still major questions which answers could have big effects at the cosmological level. Several neutrinoless double beta decay experiments are underway or planed for the near future trying to address the above questions. These experiments mainly use bolometric techniques or gaseous counters coupled with scintillator detectors. Energy resolution is significantly better in bolometric experiments but experiments coupling tracking with calorimetry have much better background rejection by identifying the two electrons produced by the double beta decay process. Another technique of detecting the electrons with reasonable energy resolution without using electronic detectors is the utilisation of nuclear emulsions. This technique has the advantage of precise tracking and vertexing even for low energy electrons, allowing a high background rejection. This possibility is presented in this paper. [Copyright &y& Elsevier]

Abstract: The ATLAS experiment (A Toroidal LHC ApparatuS) is one of the two general purpose detectors (CMS is the other) at the Large Hadron Collider, at CERN (Geneva). It is designed to study p–p collision at a center of mass energy of and at a luminosity of . ATLAS with its dimensions, 46m long, 25m in diameter and a weight of about 7000ton is the biggest collider experiment ever built. The project has involved roughly 2000 scientists and engineers of 165 institutions in 35 countries. The installation in the underground cavern is scheduled to be completed in July 2008 to be ready for the initial p–p collisions at a center of mass energy of by late summer 2008. The detector design has been optimized to cover the largest possible search of new physics at the LHC energy: Higgs bosons and alternative schemes for the spontaneous symmetry-breaking mechanism; supersymmetric particles, new gauge bosons, leptoquarks, quark and lepton compositeness, extra dimensions. At the same time high-precision measurements of Standard Model processes will be performed and this will allow more stringent tests of the present electroweak theory and an indirect search for physics beyond the Standard Model. This paper presents a comprehensive overview of the ATLAS detector prior to the first LHC collisions. [Copyright &y& Elsevier]

Abstract: Resistive Plate Chambers (RPC) have been chosen as dedicated trigger muon detectors for the Compact Muon Solenoid [CMS collaboration, Technical Design Report, CERN/LHCC 94-38, 1994. ] experiment at the Large Hadron Collider [The LHC project at CERN, LHC-project-report-36, 1996. ] at CERN. Four Italian groups from Bari, Frascati, Napoli and Pavia and two Bulgarian groups from Sofia have participated in designing and constructing the RPC barrel system. A sophisticated and complex production line has been organized by the collaboration to build the 480 RPC chambers, with a quality assurance (QA) test, made by 3 consecutive steps, in order to assure full functionality of the chambers. A final certification of the chambers has been made at ISR (CERN) with a month-long test. After that the RPCs have been coupled to the Drift Tube chamber and installed in the iron return yoke of the CMS solenoid. The first chamber was produced in 2002 and last was installed in October 2007. The system is now completely installed and commissioning has been going on since the second half of 2005 to complete the Large Hadron Collider (LHC) startup in the summer of 2008. The chamber construction, the test made, the main results achieved and a short description of all the services needed to run the RPC barrel system will be described in this paper. [Copyright &y& Elsevier]

Abstract: Presently, PHENIX is developing a fast muon trigger system based on resistive plate chambers (RPCs) combined with an upgrade of the existing muon tracker electronics. The primary goal of the PHENIX muon trigger system upgrade is to study the flavor dependent quark and antiquark polarizations in the proton by tagging high momentum muons from the W decay. For the production of the PHENIX muon trigger RPCs, we take advantage of the existing facilities and expertise that have been accumulated by the Korea Detector Laboratory (KODEL), Korea University, during the development of the forward muon trigger system for the CMS collaboration at the LHC. In this paper, we first summarize the physics motivation of the fast muon trigger system for PHENIX, and introduce the procedure for gas gap production and quality assurance plan. [Copyright &y& Elsevier]

Abstract: The ATLAS BPTX stations are composed of electrostatic button pick-up detectors, located 175m away along the beam pipe on both sides of ATLAS. The pick-ups are installed as a part of the LHC beam instrumentation and used by ATLAS for timing purposes. The usage of the BPTX signals in ATLAS is twofold: they are used both in the trigger system and for LHC beam monitoring. The BPTX signals are discriminated with a constant-fraction discriminator to provide a Level-1 trigger when a bunch passes through ATLAS. Furthermore, the BPTX detectors are used by a stand-alone monitoring system for the LHC bunches and timing signals. The BPTX monitoring system measures the phase between collisions and clock with a precision better than 100ps in order to guarantee a stable phase relationship for optimal signal sampling in the sub-detector front-end electronics. In addition to monitoring this phase, the properties of the individual bunches are measured and the structure of the beams is determined. On September 10, 2008, the first LHC beams reached the ATLAS experiment. During this period with beam, the ATLAS BPTX system was used extensively to time in the read-out of the sub-detectors. In this paper, we present the performance of the BPTX system and its measurements of the first LHC beams. [ABSTRACT FROM AUTHOR]

Abstract: The CMS experiment at the CERN Large Hadron Collider has placed great emphasis on precise calorimetry for electrons and photons. The electromagnetic calorimeter (ECAL) contains about 75000 scintillating lead tungstate crystals that are read out using sophisticated electronics. This paper will describe the ECAL and the experimental factors that influenced the choice of the technologies used in the detector design. The barrel ECAL has been installed into the experiment and installation of the endcaps will commence in early 2008. The pre-calibration and commissioning of these detectors will be described and the current status of the ECAL reviewed. The prospects for the initial operation period in 2008, when beams are first collided in the LHC, will be discussed. [Copyright &y& Elsevier]

Abstract: The ALICE Trigger electronics (TRG) has been installed in the experimental cavern and tested with each of the detectors, both individually (‘standalone’ mode) and in ‘global’ runs, i.e. those involving other detectors. Global runs were performed with cosmic ray triggers, and also during the LHC startup period in September 2008. In this paper the status of the trigger system will be reviewed, in particular describing recent extensions to the system. [Copyright &y& Elsevier]

A search for supersymmetric particles in final states with zero, one, and two leptons, with and without jets identified as originating from b-quarks, in 4.7 fb of $\sqrt{s}=7\mbox{ TeV}$ pp collisions produced by the Large Hadron Collider and recorded by the ATLAS detector is presented. The search uses a set of variables carrying information on the event kinematics transverse and parallel to the beam line that are sensitive to several topologies expected in supersymmetry. Mutually exclusive final states are defined, allowing a combination of all channels to increase the search sensitivity. No deviation from the Standard Model expectation is observed. Upper limits at 95 % confidence level on visible cross-sections for the production of new particles are extracted. Results are interpreted in the context of the constrained minimal supersymmetric extension to the Standard Model and in supersymmetry-inspired models with diverse, high-multiplicity final states. [ABSTRACT FROM AUTHOR]

The uncertainty on the calorimeter energy response to jets of particles is derived for the ATLAS experiment at the Large Hadron Collider (LHC). First, the calorimeter response to single isolated charged hadrons is measured and compared to the Monte Carlo simulation using proton-proton collisions at centre-of-mass energies of $\sqrt{s} = 900~\mbox{GeV}$ and 7 TeV collected during 2009 and 2010. Then, using the decay of K and ? particles, the calorimeter response to specific types of particles (positively and negatively charged pions, protons, and anti-protons) is measured and compared to the Monte Carlo predictions. Finally, the jet energy scale uncertainty is determined by propagating the response uncertainty for single charged and neutral particles to jets. The response uncertainty is 2-5 % for central isolated hadrons and 1-3 % for the final calorimeter jet energy scale. [ABSTRACT FROM AUTHOR]

Abstract: The ATLAS Pixel Detector is one of the largest silicon pixel hybrid detectors in the world. It has a total active area of 1.7m2 of silicon read out every 25ns by approximately 80 million electronic channels. It is the innermost tracking detector of the ATLAS experiment at the Large Hadron Collider (LHC) at CERN, designed to measure particle tracks and decay vertices with a very high precision and efficiency. Since August 2008, after more than 10 years of development and construction, the whole detector has been operated together. After tuning, calibration and timing-in the detector has demonstrated excellent noise occupancy of 10−10 and a tracking hit efficiency greater than 99.7%. The paper will describe the detector performance and discuss the studies performed with cosmic ray data, such as alignment and the Lorentz angle measurement. [Copyright &y& Elsevier]

Abstract: In this paper, we summarize the perspectives on quarkonia detection in the ALICE experiment at the CERN LHC, both in the dielectron and dimuon decay channels. [Copyright &y& Elsevier]

I review the latest heavy flavor measurements at RHIC experiments. Measurements from RHIC together with preliminary results from LHC offer us an opportunity to systematically study the sQGP medium properties. In the end, I will outlook a prospective future on precision heavy flavor measurements with detector upgrades at RHIC. [ABSTRACT FROM AUTHOR]

Thanks to its unique capabilities the ALICE experiment can measure the production of identified particles and resonances over a wide momentum range both in pp and Pb--Pb collisions at the LHC. In this report, particle-identification detectors and techniques, as well as achieved performance, are shortly reviewed. The current results on hadron transverse momentum spectra measured in pp collisions at √s = 0.9TeV and 7TeV, and in Pb--Pb collisions at √SNN = 2.76TeV are shown. In particular, proton-- proton results on particle production yields, spectral shapes and particle ratios are presented as a function of the collision energy and compared to previous experiments and commonly-used Monte Carlo models. Particle spectra, yields and ratios in Pb--Pb are measured as a function of the collision centrality and the results are compared with published RHIC data in Au--Au collisions at √SNN = 0:2TeV and predictions for the LHC. [ABSTRACT FROM AUTHOR]

The compact muon solenoid (CMS) detector at the large hadron collider (LHC) is ideal to measure the heavy flavor production, especially, in the dimuon channels in high-multiplicity environment. Compared to the pp data scaled by the number of binary collisions, the yields of prompt and non-prompt J/ψ and ϒ(1S) in Pb-Pb collisions are strongly suppressed at √SNN = 2.76 TeV. In addition, the excited ϒ(2S+3S) states are also suppressed relative to the ground ϒ(1S) state in Pb-Pb collisions. These results consistently indicate a significant medium effect on the heavy-flavor production in heavy-ion collisions at LHC. [ABSTRACT FROM AUTHOR]

We discuss the implementation of the 'minimal' type III seesaw model, i.e. with one fermionic triplet, in FeynRules/MadGraph. This is the first step in order to realize a real study of LHC data recorded in the LHC detectors. With this goal in mind, we comment on the possibility of discovering this kind of new physics at the LHC running at 7 TeV with a luminosity of few fb. [ABSTRACT FROM AUTHOR]

The Level-1 Trigger plays a major role in the CMS experiment allowing the reduction of the raw event rate at the Large Hadron Collider. Its decision is based on information from the electromagnetic and hadronic calorimeters as well as the muon detectors. The electronics of the electromagnetic calorimeter generate and deliver basic quantities called “Trigger Primitives” which correspond to local energy deposits created by electromagnetic showers. In order to ensure the correct generation of the trigger primitives by the electronics, a special software called an emulator has been implemented. It is able to reproduce the ECAL trigger functionalities at the bit level using the same inputs and identical output format. It is configured in exactly the same way as the hardware. [ABSTRACT FROM PUBLISHER]

The upgrade of the Large Hadron Collider (LHC) experiments at CERN sets new challenges for the powering of the detectors. One of the powering schemes under study is based on DC-DC buck converters mounted on the front-end modules. The hard environmental conditions impose strict restrictions to the converters in terms of low volume, radiation and magnetic field tolerance. Furthermore, the noise emission of the switching converters must not affect the performance of the powered systems. A study of the sources and paths of noise of a synchronous buck converter has been made for identifying the critical parameters to reduce their emissions. As proof of principle, a converter was designed following the PCB layout considerations proposed and then used for powering a silicon strip module prototype for the ATLAS upgrade, in order to evaluate their compatibility. [ABSTRACT FROM AUTHOR]

A process of central exclusive π+π- production in proton-proton collisions and its theoretical description is presented. A possibility of its measurement, during the special low luminosity LHC runs, with the help of the ATLAS central detector for measuring pions and the ALFA stations for tagging the scattered protons is studied. A visible cross-section is estimated to be 21 μb for √s = 7 TeV, which gives over 2000 events for 100 μb-1 of integrated luminosity. Differential distributions in pion pseudorapidities, pion and proton transverse momenta as well as π+π- invariant mass are shown and discussed. [ABSTRACT FROM AUTHOR]

The thermal neutron SEU cross-section of the Toshiba SRAM memory used in the LHC RadMon system was measured at different voltages. A method using the difference in its response compared to mixed particle energy field is proposed to be used as a discriminator between thermal neutron and high-energy hadron fluences. For test purposes, the proposed method was used at the CNGS and CERF facilities to estimate the field composition by counting SEUs at two different voltages and the results were compared to simulations. [ABSTRACT FROM AUTHOR]

In 2010, the Compact Muon Solenoid (CMS) experiment at LHC recorded over 45 pb-1 of pp collision data at $\sqrt{s} = 7~{\rm TeV}$. The large collected datasets are of very high quality and have been used to commission and calibrate the CMS detector, with the achieved performance close to the TDR specifications. CMS has re-established all the major Standard Model processes in the 2010 Run and is entering new territory in searches for New Physics, with sensitivity already exceeding that at LEP and TeVatron. [ABSTRACT FROM AUTHOR]

The cascade mass reconstruction approach was used for mass reconstruction of the lightest $$ \tilde \tau $$ produced at the LHC in the cascade decay $$ \tilde g \to \tilde bb \to \tilde \chi _2^0 bb \to \tilde \tau _1 \tau bb \to \tilde \chi _1^0 \tau \tau bb $$. The $$ \tilde \tau _1 $$ mass was reconstructed assuming that masses of gluino, bottom squark, and two lightest neutralinos were reconstructed in advance. SUSY data sample sets for the SU(3) model point containing 160k events each were generated which corresponded to an integrated luminosity of about 8 fb at 14 TeV. These events were passed through the AcerDET detector simulator, which parametrized the response of a generic LHC detector. The mass of the $$ \tilde \tau _1 $$ was reconstructed with a precision of about 20% on average. [ABSTRACT FROM AUTHOR]