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:
824
Journal Article
Recenzirano
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.
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.
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.
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 describes the novel, unique in High Energy Physics, real-time alignment and calibration of the full LHCb detector. The LHCb experiment has been designed as a dedicated heavy flavour ...physics experiment focused on the reconstruction of c and b hadrons. The LHCb detector is a single-arm forward spectrometer, which measures proton-proton interactions at the LHC. The operational bunch crossing rate is several orders of magnitude above the current abilities of data recording and storage. Therefore, a trigger system has been implemented to reduce this rate to an acceptable value. The LHCb trigger system has been redesigned during the 2013–2015 long shutdown,achieving offline-quality alignment and calibration online. It also allows analyses to be performed entirely at the trigger level. In addition, having the best performing reconstruction in the trigger gives the possibility to fully use the particle identification selection criteria and greatly increases the efficiency, in particular for the selection of charm and strange hadron decays. This results in enhancing the physics programme of the LHCb experiment.
Purpose
In this study, the functional mid-term outcomes of the modified Grammont and Langenskiöld technique was assessed in skeletally immature patients with habitual patellar dislocation, with ...emphasis on knee function, pain, and other possible post-surgical complications. This is the first study concerning the application of the modified Grammont and Langenskiöld technique in habitual patellar dislocations.
Methods
This retrospective cohort study considered 10 patients (15 knees), ranging from 7 to 11 years old, who underwent the modified Grammont and Langenskiold procedure between 2015 and 2018. History of dislocation, patellar stability and range of motion (ROM) were analysed. To assess functional improvement and knee pain, the Kujala Anterior Knee Pain Scale and KOOS-Child Knee Survey were used before and after surgical treatment.
Results
No history of dislocation was noted after surgical treatment. All 15 knees showed full ROM. There were no signs of genu recurvatum and no length discrepancies were found. The subjective assessment revealed significant improvement in the scores of the KOOS-Child questionnaire in all five sections (
p
< 0.001), as well as in The Kujala Anterior Knee Pain Scale (
p
= 0.001).
Conclusion
The modified Grammont and Langenskiöld technique yields remarkable results in terms of knee stability and knee function, while decreasing recurrence risk and intensity of pain in patients with challenging cases of patellofemoral joint dislocation. This surgical technique is most effective in cases where the patella remains dislocated continuously; however, it may also be used in immature patients with recurrent instability.
Level of evidence
IV.
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