Higgs self coupling measurement

A measurement of the Higgs self coupling from e+e- collisions in the International Linear Collider is presented. The impact of the detector performance in terms of $b$-tagging and particle flow is investigated.Comment: LCWS Proceedin

Modeling and Lyapunov-designed based on adaptive gain sliding mode control for wind turbines

In this paper, modeling and the Lyapunov-designed control approach are studied for the Wind Energy Conversion Systems (WECS). The objective of this study is to ensure the maximum energy production of a WECS while reducing the mechanical stress on the shafts (turbine and generator). Furthermore, the proposed control strategy aims to optimize the wind energy captured by the wind turbine operating under rating wind speed, using an Adaptive Gain Sliding Mode Control (AG-SMC). The adaptation for the sliding gain and the torque estimation are carried out using the sliding surface as an improved solution that handles the conventional sliding mode control. Furthermore, the resultant WECS control policy is relatively simple, meaning the online computational cost and time are considerably reduced. Time-domain simulation studies are performed to discuss the effectiveness of the proposed control strateg

Sveobuhvatan pregled LVRT mogućnosti i kliznog režima upravljanja vjetroagregata spojenog na mrežu s dvostruko napajanim asinkronim generatorom

In this paper, a comprehensive review of several strategies applied to improve the Low Voltage Ride-Through (LVRT) capability is presented for grid-connected wind-turbine-driven Doubly Fed Induction Generator (DFIG). Usually, the most proposed LVRT solutions in the literature based on: hardware solutions, which increase the system costs and software solutions, which increase the control system complexity. Therefore, the main objective of this study is to take into account grid requirements over LVRT performance under grid fault conditions using software solution based on Higher Order-Sliding Mode Control (HOSMC). Effectively, this control strategy is proposed to overcome the chattering problem and the injected stator current harmonics into the grid of the classical First Order Sliding Mode (FOSMC). Furthermore, the resultant HOSMC methodology is relatively simple; where, the online computational cost and time are considerably reduced. The LVRT capacity and effectiveness of the proposed control method, compared to the conventional FOSMC, are validated by time-domain simulation studies under Matlab on a 1.5 MW wind-turbine-driven DFIG.U ovom radu, prikazan je sveobuhvatan pregled strategija primjenjenih za poboljšanje sposobnosti rada tijekom prolaznih smetnji niskog napona mreže za vjetroagregat s dvostruko napajanim asinkronim generatorom (DFIG). Uobičajeno, većina predloženih LVRT rješenja u literaturi temelji se na: hardverskim rješenjima, što povećava troškove sustava i softverskih rješenja te složenost sustava upravljanja. Stoga je glavni cilj ovog istraživanja da se uključuje i zahtjevi mreže kroz ponašanje LVRTa u uvjetima mrežnih kvarova korištenjem softverskog rješenja zasnovanoga na kliznom režimu rada višeg reda (HOSMC). Efektivno, ova upravljačka strategija je predložena kako bi se prevladali oscilacije i ubacivanje harmonika struje statora u mrežu klasičnim metodama kliznog režima rada prvog reda (FOSMC). Nadalje, rezultantna metodologija HOSMC je relativno jednostavna; gdje su online računski zahtjevi i potrebno vrijeme značajno smanjeni. LVRT kapacitet i učinkovitost predložene metode upravljanja, u usporedbi s konvencionalnim FOSMC potvrđene su simulacijama u vremenskoj domeni u Matlabu na 1.5 MW vjetroagregatu s DFIG-om

Dual Robust Control of Grid-Connected DFIGs-Based Wind- Turbine-Systems under Unbalanced Grid Voltage Conditions

In this chapter, a comparative analysis is made for doubly-fed induction-generator (DFIG) low-voltage ride-through (LVRT) solutions. It is supposed to improve the LVRT capability of DFIG under unbalanced grid voltage conditions by hardware or software solutions. Therefore, this chapter proposes a low-cost software LVRT solution based on an efficient control scheme of DFIG driven by a wind turbine. The proposed control scheme is based on dual-sequence decomposition technique and Lyapunov-based robust control (RC) theory. Under an unbalanced grid voltage conditions, the proposed control strategy not only eliminates effectively the oscillations of the active and reactive powers exchanged between the generator and the grid but also achieves the symmetrical and sinusoidal grid currents injection. Simulation analysis under MATLAB®/Simulink® has been carried out on a 1.5 MW DFIG-based wind-turbine-systems, and the results are presented and discussed to demonstrate the feasibility and the efficiency of the control strategy for a grid-connected application under unbalanced voltage supply. The proposed dual control scheme is shown to be able to successfully mitigate torque, stator power and currents pulsations as compared with the conventional vector control based on the single control scheme

ATLAS Calorimeter: Run 2 performance and Phase-II upgrades

International audienceThe ATLAS detector was designed and built to study proton-proton collisions produced at the LHC at centre-of-mass energies up to 14 TeV and instantaneous luminosities up to $10^{34}cm^{−2}s^{−1}$. A Liquid Argon-lead sampling (LAr) calorimeter is employed as electromagnetic and hadronic calorimeters, except in the barrel region, where a scintillator-steel sampling calorimeter (TileCal) is used as hadronic calorimeter. This presentation gives first an overview of the detector operation and data quality, as well as of the achieved performances of the ATLAS calorimetry system. Additionally the upgrade projects of the ATLAS calorimeter system for the high luminosity phase of the LHC (HL-LHC) are presented. For the HL-LHC, the instantaneous luminosity is expected to increase up to $L≃7.5×10^{34}cm^{−2}s^{−1}$ and the average pile-up up to 200 interactions per bunch crossing. The major R&D item is the upgrade of the electronics for both LAr and Tile calorimeters in order to cope with longer latencies of up to 60 μs. The expected radiation doses will exceed the qualification range of the current readout system. The status of the R&D of the low-power ASICs (pre-amplifier, shaper, ADC, serializer and transmitters) and readout electronics for all the design options is discussed. Moreover, a High Granularity Timing Detector (HGTD) is proposed to be added in front of the LAr calorimeters in the end-cap region (2.4 <|η|< 4.2) for pile-up mitigation at Level-0 trigger level and offline reconstruction. The HGTD will correlate the energy deposits in the calorimeter to different proton-proton collision vertices by using TOF information with high time resolution (30 pico-seconds per readout cell) based on the Silicon sensor technologies. The current test beam results are presented in this document as well

Calibration and monitoring of the ATLAS Tile calorimeter

The ATLAS Tile Calorimeter (TileCal) is the central section of the hadronic calorimeter of the ATLAS experiment and provides important information for reconstruction of hadrons, jets, hadronic decays of tau leptons and missing transverse energy. This sampling calorimeter uses steel plates as absorber and scintillating tiles as active medium. The light produced by the passage of charged particles is transmitted by wavelength shifting fibres to photomultiplier tubes (PMTs). PMT signals are then digitized at 40~MHz and stored on detector and are only transferred off detector once the first level trigger acceptance has been confirmed. The readout is segmented into about 5000 cells (longitudinally and transversally), each of them being read out by two PMTs in parallel. To calibrate and monitor the stability and performance of each part of the readout chain, a set of calibration systems is used. The TileCal calibration system comprises Cesium radioactive sources, laser, charge injection elements and an integrator based readout system. Combined information from all systems allows to monitor and equalize the calorimeter response at each stage of the signal production, from scintillation light to digitisation. Calibration runs are monitored from a data quality perspective and used as a cross-check for physics runs. Data quality in physics runs is monitored extensively and continuously. Problems are reported and immediately investigated. The data quality efficiency achieved was 99.6\% in 2012, 100\% in 2015 and 98.9\% in 2016. Based on LHC Run~1 experience, several calibration systems were improved for Run~2. The lessons learned, the modifications, and the LHC Run~2 performance, between 2015 and 2017, are discussed, including the calibration, stability, absolute energy scale, uniformity and time resolution. These results show that the TileCal performance is within the design requirements and has given essential contributions to reconstructed objects and physics results

Timing for the ATLAS Phase-II Upgrade

International audienceThe Large Hadron Collider (LHC) at CERN will deliver an integrated luminosity of up to $4000~{\rm fb}^{-1}$ in the high-luminosity phase (HL) thanks to an increased instantaneous luminosity that will reach up to $7.5 \times 10^{34}~{\rm cm}^{-2}{\rm s}^{-1}$. The ATLAS detector will be upgraded during Long Shutdown periods. This upgrade will allow the detector to cope with the high luminosity that will be accompanied by a high pileup. A powerful new way to mitigate the effects of pileup is to use high-precision timing information to distinguish between collisions occurring close in space but well-separated in time. A High-Granularity Timing Detector, based on low gain avalanche detector technology, is therefore proposed for the ATLAS Phase-II upgrade. This new detector will improve the detector physics performance in the forward region, in a pseudorapidity range of 2.4 to 4.0. Its design was optimised to associate a time to each track with a target average time resolution of $30~{\rm ps}$ for a minimum-ionising particle at the start of the detector lifetime, increasing to $50~{\rm ps}$ at the end of HL-LHC operation

ATLAS Tile calorimeter calibration and PMT response

The ATLAS Tile Calorimeter (TileCal) is the central section of the hadronic calorimeter of the ATLAS experiment. It provides important information for reconstruction of hadrons, jets, hadronic decays of tau leptons and missing transverse energy. This sampling calorimeter uses steel plates as absorber and scintillating tiles as active medium. Scintillating light is transmitted by wavelength shifting fibres to photomultiplier tubes (PMTs) in the rear girders of the wedge-shaped calorimeter modules. Photomultiplier signals are then digitized at 40 MHz and stored on detector in digital pipelines. Event data are transmitted off detector upon a first level trigger acceptance, at a maximum rate of 100 kHz). The readout is segmented into about 5000 cells, each read out by two PMTs on opposite sides of the cell. To calibrate and monitor the stability and performance of each part of the readout chain during the data taking, a set of calibration systems is used. The TileCal calibration system comprises Cesium radioactive sources, laser, charge injection elements and an integrator based readout system. Combined information from all systems allows to monitor and equalise the calorimeter response at each stage of the signal production, from scintillation light to digitisation. After exposure to scintillator light for almost 10 years, variations in gain have been observed when the PMTs are exposed to large light currents. These variations have been studied and correlated to some intrinsic properties of the PMTs, including the quantum efficiency, as well as operation conditions like the High Voltage. Latest results and conclusions will be presented

ATLAS Calorimeters: Run-2 performance and Phase-II upgrade

The ATLAS detector was designed and built to study proton-proton collisions produced at the LHC at centre-of-mass energies up to 14 TeV and instantaneous luminosities up to 10^{34} cm^{−2} s^{−1}. A liquid argon (LAr)-lead sampling calorimeter is employed as electromagnetic calorimeter and hadronic calorimter, except in the barrel region, where a scintillator-steel sampling calorimeter (TileCal) is used as hadronic calorimter. This presentation will give first an overview of the detector operation and data quality, as well as the achieved performance of the ATLAS calorimetry system. Additionally, the upgrade projects of the ATLAS calorimeter system for the high luminosity phase of the LHC (HL-LHC) will be presented. For the HL-LHC, the instantaneous luminosity is expected to increase up to L ≃ 7.5 × 10^{34} cm^{−2} s^{−1} and the average pile-up up to 200 interactions per bunch crossing. The major R&D item is the upgrade of the electronics for both LAr and Tile calorimeters in order to cope with longer latencies of up to 60 us. The expected radiation doses will exceed the qualification range of the current readout system. The status on the R&D of the low-power ASICs (pre-amplifier, shaper, ADC, selializer and transmitters) and readout electronics for all the design options will be discussed. Moreover, a High Granularity Timing Detector (HGTD) is proposed to be added in front of the LAr calorimeters in the end-cap region (2.4 <|eta|< 4.2) for pile-up mitigation at Level-0 trigger level and offline reconstruction. The HGTD will correlate the the energy deposits in the calorimeter to different proton-proton collision vertices by using TOF information with high time resolution (30 pico-second per readout cell) based on the Silicon sensor technologies. The current test beam results will be presented as well