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Measurements of jet cross-section ratios with ATLAS
No full textJet cross-section ratios between inclusive bins of jet multiplicity are measured differentially in variables that are sensitive to either the energy-scale or angular distribution of hadronic energy flow in the final state. Several improvements to the calibration of jets are described, which result in significant improvements in the overall jet energy scale uncertainty. The measurements are compared to state-of-the-art NLO and NNLO predictions, and used to determine the strong-coupling constant at the reference scale of the Z-boson mass and its running up to high energies
New techniques for reconstructing and calibrating hadronic objects with ATLAS
No full textThe precision and reach of physics analyses at the LHC is often tied to the performance of hadronic object reconstruction & calibration, with any incremental gains in understanding & reduced uncertainties being impactful on ATLAS results. Recent refinements to the reconstruction and calibration procedures for jets & missing energy by the ATLAS collaboration has resulted in reduced uncertainties, improved pileup stability and overall performance gains. In this contribution, highlights of these developments will be presented
LHCb RICH Fast-timing photon detection at the SPS charged particle beam
No full textThe use of a new optoelectronic readout chain with (100)ps time resolution is a major milestone in thedevelopment of RICH detectors for environments with a high number ofparticle interactions per bunch crossing, such as theHigh-Luminosity LHC. A prototype chain, based on MAPMT and SiPMphoton sensors coupled to readout electronics integrating the FastICASIC and a TDC-in-FPGA, is presented. The FastIC is an 8-channelASIC for analogue-to-digital conversion with 25 ps timeresolution. This ASIC is the predecessor of the FastRICH ASIC forthe LHCb RICH upgrades. The signals from the photon detectors aretimestamped in a custom multi-channel TDC-in-FPGA designed using amulti-phase clock sampling architecture with an average bin width of150 ps. The prototype optoelectronic readout chain was tested in acharged particle beam of 180 GeV/c hadrons at the CERN SPSfacility. The reference time-of-arrival of the particle tracks wasmeasured with about 100 ps time resolution and the number of tracksper event was registered using a particle tracking system. Thesingle-photon time resolution of the MAPMT sensors is extractedusing a binned method in order to correct for the calibrated TDC binwidths and detector time-walk. The resulting best estimate of σ = 182 ± 24 ps is in agreement with pulsed-laser measurementsin the lab and consistent with the expectations from themanufacturer.Abstract
The use of a new optoelectronic readout chain with
(100)ps time resolution is a major milestone in the
development of RICH detectors for environments with a high number of
particle interactions per bunch crossing, such as the
High-Luminosity LHC. A prototype chain, based on MAPMT and SiPM
photon sensors coupled to readout electronics integrating the FastIC
ASIC and a TDC-in-FPGA, is presented. The FastIC is an 8-channel
ASIC for analogue-to-digital conversion with 25 ps time
resolution. This ASIC is the predecessor of the FastRICH ASIC for
the LHCb RICH upgrades. The signals from the photon detectors are
timestamped in a custom multi-channel TDC-in-FPGA designed using a
multi-phase clock sampling architecture with an average bin width of
150 ps. The prototype optoelectronic readout chain was tested in a
charged particle beam of 180 GeV/c hadrons at the CERN SPS
facility. The reference time-of-arrival of the particle tracks was
measured with about 100 ps time resolution and the number of tracks
per event was registered using a particle tracking system. The
single-photon time resolution of the MAPMT sensors is extracted
using a binned method in order to correct for the calibrated TDC bin
widths and detector time-walk. The resulting best estimate of
σ = 182 ± 24 ps is in agreement with pulsed-laser measurements
in the lab and consistent with the expectations from the
manufacturer
Design and construction of the CMS Outer Tracker for the Phase-2 Upgrade
No full textThe High Luminosity LHC (HL-LHC) is expected to deliver an integrated luminosity of ~fb after 10 years of operation with peak instantaneous luminosity reaching about cms. During Long Shutdown 3, several components of the CMS detector will undergo major changes, called Phase-2 upgrade, to be able to operate in the challenging environment of the HL-LHC. The current CMS silicon strip tracker has to be replaced with a new detector. The Phase-2 Outer Tracker (OT) will have higher radiation tolerance, higher granularity, and the capability to handle higher data rates compared to the current system. Another key feature of the OT will be to provide tracking information to the Level-1 (L1) trigger, allowing trigger rates to be kept at a sustainable level without sacrificing physics potential. For this, the OT will be made out of modules with two closely spaced sensors read out by front-end ASICs, which can correlate hits in the two sensors creating short track segments called stubs. The stubs will be used for tracking in the L1 track finder. The modules come in two flavors: strip-strip (2S) and pixel-strip (PS), which contain different sensor configurations and multiple ASICs. In this contribution, the design of the CMS Phase-2 OT, the technological choices, and the quality assurance (QA) procedures used to ensure the functionality of the modules will be reported. The contribution will cover the first results with pre-production devices and the different aspects taken into account during the QA: from fulfilling the precision specification of the module assembly procedure to ensuring the proper communication between the different ASICs on the module. The module noise performance is also checked and the full module functionality is verified at different temperatures
HL-LHC TDE Preliminary Design Review
No full textA new Target Dumps External (TDE) design, compatible with HL-LHC beam parameters, has been developed for the HL-LHC. In this Design Review (DR), the design that has been developed to meet the requirements of HL will be presented in detail. The maturity of the design in each area is dependent on the subsequent timescales for procurement and implementation. In the areas of the core and vessel, the design will be fully defined, and this will act essentially as a manufacturing readiness review. In other areas, such as the cooling system, this will act as a preliminary design review as there may still be further refinements and detailed design aspects to develop
Physics case for low- QCD studies at FCC-ee
No full textMeasurements of hadronic final states in collisions at centre-of-mass (CM) energies below the Z peak can notably extend the FCC-ee physics reach in terms of precision quantum chromodynamics (QCD) studies. Hadronic final states can be studied over a range of hadronic energies \sqrt{s_\mathrm{had}} \approx 20\mbox{--}80\,\mathrm{GeV} by exploiting events with hard initial- and final-state QED radiation (ISR/FSR) during the high-luminosity Z-pole run, as well as in dedicated short (about one month long) runs at CM energies and . Using realistic estimates and fast detector simulations, we show that data samples of about hadronic events can be collected at the FCC-ee at each of the low-CM-energy points. Such datasets can be exploited in a variety of precision QCD measurements, including studies of light-, heavy-quark and gluon jet properties, hadronic event shapes, fragmentation functions, and nonperturbative dynamics. This will offer valuable insights into strong interaction physics, complementing data from nominal FCC-ee runs at higher center-of-mass energies, and
Projections for Key Measurements in Heavy Flavour Physics
No full textPrecision studies of flavour-changing processes involving quarks and leptons provide a number of ways to improve knowledge of the Standard Model and search for physics beyond it. There are excellent short- and mid-term prospects for significantly improved measurements in heavy flavour physics (involving and hadrons and leptons), with upgrades in progress or planned for the ATLAS, CMS and LHCb experiments exploiting proton-proton collisions at CERN’s Large Hadron Collider, and for the Belle II experiment operating with electron-positron collisions from the SuperKEKB accelerator in KEK. The expected sensitivities that can be achieved from these experiments for a number of key observables are presented, highlighting the complementarity of the different experiments and showing how the precision will improve with time. This international programme in heavy flavour physics will result in unprecedented capability to probe this sector of the Standard Model and, potentially, observe imprints of physics at higher energy scales than can be accessed directly