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Derniers ajouts:
2019-05-28
16:31
CP-violation in B-meson decays
Reference: Poster-2019-693
Created: 2019. -1 p
Creator(s): Koliiev, Serhii

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Conference LHCb Poster
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2019-05-23
14:45
Search for time-dependent CP violation in Charm at LHCb
Reference: Poster-2019-692
Keywords:  LHCb  CP violation  Charm
Created: 2019. -1 p
Creator(s): Pajero, Tommaso

A measurement of the time-dependent $CP$ asymmetries in the decay of $D^{0}$ mesons into $K^{+}K^{-}$ and $\pi^{+}\pi^{-}$ final states, using the data collected by LHCb during 2015—2016, is presented. Its average with the LHCb Run 1 results is the most precise measurement of the $CP$ violation parameter $A_\Gamma$ to date. No evidence of $CP$ violation is found.

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2019-05-23
10:57
Time-dependent CP violation in $B^0_s$ decays at LHCb
Reference: Poster-2019-691
Keywords:  LHCb  CP Violation
Created: 2019. -1 p
Creator(s): Gabriel, Emmy Pauline Maria

Time-dependent CP-violation measurements of beauty mesons allow the determination of the mixing-induced CP-violating phases phi_s and beta. The measurement of the phase phi_s in the Bs-Bsbar system is one of the key goals of the LHCb experiment due to the sensitivity to physics beyond the Standard Model (BSM). The CP-violating phase is of interest in penguin dominated b->s transitions, in addition to that of tree-level decays, which test the flavour changing neutral current interaction describing B mixing. Both are sensitive to BSM phases and provide valuable tests and constraints. We present new results of time-dependent CP violation using data collected at LHCb between 2011 and 2016.

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Conference LHCb Poster
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2019-05-14
15:55
THE NEW INJECTION REGION OF THE CERN PS BOOSTER
Reference: Poster-2019-690
Keywords:  PSB  PS Booster  Charge exchange Injection  Stripping  H-
Created: 2019. -1 p
Creator(s): Weterings, Wim; Bracco, Chiara; Jorat, Louise Olivia; Meddahi, Malika; Noulibos, Remy [...]

During the Long Shutdown 2 (LS2) at CERN, the new Linac4 (L4) accelerator will be connected to the PS Booster (PSB) to inject 160 MeV H− beam into the 4 superposed PSB rings. In order to achieve this, we have designed, built and pre-assembled a completely new H− charge-exchange injection chicane system, with a carbon stripping foil unit to convert the negative hydrogen ions into protons by stripping off the electrons. In parallel, we have built and installed a test stand in the L4 transfer line enabling us to gain valuable experience with operation of the stripping foil system and to evaluate different foil types during the L4 reliability runs. This paper describes the final design of the new PSB injection region and reports on the important test results obtained with the stripping foil test stand.

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2019-05-13
11:24
DESIGN AND CONSTRUCTION OF THE CERN SPS EXTRACTION PROTECTION ELEMENTS FOR LIU
Reference: Poster-2019-689
Created: 2019. -1 p
Creator(s): Balhan, Bruno

At CERN, the SPS synchrotron is equipped with two fast extraction channels towards the LHC. As a part of the LHC injector upgrade project (LIU), the protection devic- es upstream of the septa in both extraction channels will be upgraded. Various failure scenarios have been studied and presented in the past, but the definitive approach for the equipment protection upgrade for each channel has now been determined. This paper describes the consequences of the most significant failure scenarios and the impact of the heat deposition in the diluter. The resulting material stresses are evaluated. The detailed layout for the extraction protection equipment for each extraction channel is outlined. The final layout consists of a extended diluter in Long Straight Section (LSS) 6 (TPSG6) and the installation of an additional mov- able absorber (TPSC4) upstream of the quadrupole in front of the existing protection equipment in LSS 4. The detailed mechanical design of the TPSC4 and the construction status of both TPSC4 and TPSG6 are discussed.

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2019-04-05
14:12
The LHCb Vertex Detector Upgrade. The prototypes study with the Timepix3 Telescope
Reference: Poster-2019-688
Created: 2019. -1 p
Creator(s): Rachwal, Bartlomiej

A dedicated irradiation programme with a particle beam followed by detailed studies are essential for proper evaluation of detector prototypes and predict their performance after accumulating the predicted particle fluence at the end of their lifetime. In order to perform precise measurements with the LHCb VELO (Vertex Locator) detector prototypes a dedicated high-resolution pixel beam telescope was developed based on 8 Timepix3 detector planes. This telescope has been taking data at CERN in the PS and SPS facilities since 2014. The Timepix3 can operate in a trigger less mode (data driven readout) with very precise timestamps. The data produced by the telescope can easily incorporate the signals from the Device Under Test (DUT) and in particular for Timepix3 devices the analysis is straight forward. The offline analysis compares the performance after irradiation with several fluences of protons or neutrons from 2 to 8 $\times 10^{15}$ 1-MeV $n_{eq}/cm^2$ ; different silicon substrates (n-on-p or n-on-n), distances from last pixel to the edge, guard rings designs and different vendors. Charge collection efficiencies, track resolution, eta correction are of particular interest as function of fluence. The presentation will describe the detailed LHCb VELO upgrade design choices as well as with some highlights of the Timepix3 Telescope operational performance.

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VIII International Course "Detectors and Electronics for High Energy Physics, Astrophysics, Space Applications and Medical Physics"
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2019-03-29
13:42
CERN Knowledge Transfer Posters
Reference: Poster-2019-686
Created: 2016. -18 p
Creator(s): Tvede, Linn

CERN's various areas of expertise translates into impact across industries beyond CERN. Find out more at kt.cern

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2019-03-15
09:54
Machine Learning approach to boosting neutral particles identification in the LHCb calorimeter
Reference: Poster-2019-685
Keywords:  Electromagnetic Calorimeter  Neutral particles identification  Machine learning
Created: 2019. -1 p
Creator(s): Boldyrev, Alexey

We present a new approach to identification of boosted neutral particles using Electromagnetic Calorimeter (ECAL) of the LHCb detector. The identification of photons and neutral pions is currently based on expected properties of the objects reconstructed in the calorimeter. This allows to distinguish single photons in the electromagnetic calorimeter from overlapping photons produced from high momentum $\pi^0$ decays. The proposed approach is based on applying machine learning techniques to primary calorimeter information, that are energies collected in individual cells around the energy cluster. The machine learning model employs extreme gradient boosting trees approach which is widely used nowadays, and separates $\pi^0$ and photon responses from "first principles". This approach allowed to significantly improve separation performance score on simulated data, reducing primary photons fake rate by factor of four. In this presentation we will present the approach, evaluate its performance obtained on MC samples, and discuss specific issues when transferring discriminative models from simulation to real world.

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ACAT 2019
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2019-03-15
09:51
Tracking performance for long-lived particles at LHCb
Reference: Poster-2019-684
Keywords:  LHCb  Data-driven  Downstream  Tracking  Efficiency
Created: 2019. -1 p
Creator(s): Garcia Martin, Luis Miguel

The LHCb experiment is dedicated to the study of the $c$- and $b$-hadrons decays, including long living particles such as $K_s$ and strange baryons ($\Lambda$, $\Xi$, etc... ). These kind of particles are difficult to reconstruct from LHCb tracking systems since they escape the detection in the first tracker. A new method to evaluate the performance in terms of efficiency and throughput of the different tracking algorithms for long living particles have been developed. Special emphasis is laid on particles hitting only part of the tracking system of the new LHCb upgrade detector.

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ACAT 2019
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2019-03-15
09:11
Physics and computing performance of reconstruction algorithms for the GPU High Level Trigger 1 of LHCb
Reference: Poster-2019-683
Keywords:  CERN LHC  LHCb  HLT1  GPU
Created: 2019. -1 p
Creator(s): Vom Bruch, Dorothea

Beginning in 2021, the upgraded LHCb experiment will use a triggerless readout system collecting data at an event rate of 30 MHz. A software-only High Level Trigger will enable unprecedented flexibility for trigger selections. During the first stage (HLT1), a sub-set of the full offline track reconstruction for charged particles is run to select particles of interest based on single or two-track selections. After this first stage, the event rate is reduced by at least a factor 30. Track reconstruction at 30 MHz represents a significant computing challenge, requiring a renovation of current algorithms and the underlying hardware. In this talk we present work based on an R&D project in the context of the LHCb Upgrade I exploring the approach of executing the full HLT1 chain on GPUs. This includes decoding the raw data, clustering of hits, pattern recognition, as well as track fitting. We will discuss the development of algorithms optimized for many-core architectures. Both the computing and physics performance of the full HLT1 chain will be presented.

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ACAT 2019
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