The LHCb trigger and its upgrade Dziurda, A.
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
07/2016, Letnik:
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Journal Article
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The current LHCb trigger system consists of a hardware level, which reduces the LHC inelastic collision rate of 30MHz, at which the entire detector is read out. In a second level, implemented in a ...farm of 20k parallel-processing CPUs, the event rate is reduced to about 5kHz. We review the performance of the LHCb trigger system during Run I of the LHC. Special attention is given to the use of multivariate analyses in the High Level Trigger. The major bottleneck for hadronic decays is the hardware trigger. LHCb plans a major upgrade of the detector and DAQ system in the LHC shutdown of 2018, enabling a purely software based trigger to process the full 30MHz of inelastic collisions delivered by the LHC. We demonstrate that the planned architecture will be able to meet this challenge.
An evolved real-time data processing strategy is proposed for high-energy physics experiments, and its implementation at the LHCb experiment is presented. The reduced event model allows not only the ...signal candidate firing the trigger to be persisted, as previously available, but also an arbitrary set of other reconstructed or raw objects from the event. This allows for higher trigger rates for a given output data bandwidth, when compared to the traditional model of saving the full raw detector data for each trigger, whilst accommodating inclusive triggers and preserving data mining capabilities. The gains in physics reach and savings in computing resources already made possible by the model are discussed, along with the prospects of employing it more widely for Run 3 of the Large Hadron Collider.
An evolved real-time data processing strategy is proposed for high-energy physics experiments, and its implementation at the LHCb experiment is presented. The reduced event model allows not only the ...signal candidate firing the trigger to be persisted, as previously available, but also an arbitrary set of other reconstructed or raw objects from the event. This allows for higher trigger rates for a given output data bandwidth, when compared to the traditional model of saving the full raw detector data for each trigger, whilst accommodating inclusive triggers and preserving data mining capabilities. The gains in physics reach and savings in computing resources already made possible by the model are discussed, along with the prospects of employing it more widely for Run 3 of the Large Hadron Collider.
A group of Early-Career Researchers (ECRs) has been given a mandate from the European Committee for Future Accelerators (ECFA) to debate the topics of the current European Strategy Update (ESU) for ...Particle Physics and to summarise the outcome in a brief document 1. A full-day debate with 180 delegates was held at CERN, followed by a survey collecting quantitative input. During the debate, the ECRs discussed future colliders in terms of the physics prospects, their implications for accelerator and detector technology as well as computing and software. The discussion was organised into several topic areas. From these areas two common themes were particularly highlighted by the ECRs: sociological and human aspects; and issues of the environmental impact and sustainability of our research.
The LHCb collaboration has redesigned its trigger to enable the full offline detector reconstruction to be performed in real time. Together with the real-time alignment and calibration of the ...detector, and a software infrastructure to make persistent the high-level physics objects produced during real-time processing, this redesign enabled the widespread deployment of real-time analysis during Run 2. We describe the design of the Run 2 trigger and real-time reconstruction, and present data-driven performance measurements for a representative sample of LHCb's physics programme.
Background Aspirin-exacerbated respiratory disease (AERD) is recognized as a distinct asthma phenotype. It usually has a severe course accompanied by chronic hyperplastic eosinophilic sinusitis with ...nasal polyps, blood eosinophilia, and increased concentrations of urinary leukotriene E4 (LTE4 ). More insightful analysis of individual patients shows this group to be nonhomogeneous. Objective We sought to identify any likely subphenotypes in a cohort of patients with AERD through the application of latent class analysis (LCA). Methods Clinical data from 201 patients with AERD (134 women) were collected from questionnaires. Standard spirometry, atopy traits, blood eosinophilia, and urinary LTE4 concentrations were evaluated. LCA was applied to identify possible AERD subphenotypes. Results Four classes (subphenotypes) within the AERD phenotype were identified as follows: class 1, asthma with a moderate course, intensive upper airway symptoms, and blood eosinophilia (18.9% of patients); class 2, asthma with a mild course, relatively well controlled, and with low health care use (34.8% of patients); class 3, asthma with a severe course, poorly controlled, and with severe exacerbations and airway obstruction (41.3% of patients); and class 4, poorly controlled asthma with frequent and severe exacerbations in female subjects (5.0% of patients). Atopic status did not affect class membership. Patients with particularly intensive upper airway symptoms had the highest levels of blood eosinophilia and the highest concentrations of urinary LTE4. Conclusions LCA revealed unique AERD subphenotypes, thus corroborating the heterogeneity of this population. Such discrimination might facilitate more individualized treatment in difficult-to-treat patients.
This document reports the first measurements of the time-dependent CP violating observables in Bs0→Ds∓K± decays. The measurements are performed using data corresponding to an integrated luminosity of ...1fb−1 collected in 2011 by the LHCb detector. The CP violating observables: Cf=0.53±0.25±0.04, AfΔΓ=0.37±0.42±0.20, Af‾ΔΓ=0.20±0.41±0.20, Sf=1.09±0.33±0.08, Sf‾=0.36±0.34±0.08 are found, where the uncertainties are statistical and systematic. Later, these observables are used to deterimine the CKM angle γ from Bs0→Ds∓K± decays. A γ value of (115−43+28)° modulo 180° at 68% CL is found, where the uncertainty contains both statistical and systematic components.
So far, the legal representation of the State Treasury has raised serious doubts in Polish law. They were eliminated by the Act of 16 December 2016 on the principles of state property management. It ...aligned the provisions on legal (material) representation of the State Treasury with those concerning representation before courts and other authorities.
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