CERN Accelerating science

Posters

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2017-11-09
14:55
Silicon photomultiplier arrays for the LHCb scintillating fibre tracker
Reference: Poster-2017-604
Keywords:  SiPM  Scintillating fibre  LHCb  SciFi tracker  Multichannel array  Neutron irradiation  Single photon detection
Created: 2017. -1 p
Creator(s): Girard, Olivier Goran; Haefeli, Guido; Kuonen, Axel Kevin; Stramaglia, Maria Elena

For the LHCb detector upgrade in 2019, a large scale scintillating fibre tracker read out with silicon photomultipliers is under construction. The harsh radiation environment (neutron and ionising radiation), the 40MHz read-out rate of the trigger less system and the large detector surface of 320m2 impose many challenges. We present the results from lab tests with 1MeV electrons and from the SPS test facility at CERN for the mulitchannel SiPM array that combines peak photo-detection efficiency of 48% and extremely low correlated noise. The measurements were performed with detectors irradiated with neutrons up to a fluence of 12*1011 neq/cm2 and single photon detection was maintained. First results of the characterization of the pre-series of 500 detectors delivered by Hamamatsu and irradiation studies on a large sample will be included.

Related links:
IEEE NSS MIC 2017
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2017-11-03
15:42
Partially Reconstructed Beauty Decays at LHCb for the Phase-II Upgrade
Reference: Poster-2017-603
Keywords:  LHCb
Created: 2017. -1 p
Creator(s): Smith, Iwan Thomas

Semileptonic beauty decays provide a theoretically clean probe of CKM Unitarity since their decay rates factorise into leptonic and hadronic currents. At hadron colliders the full kinematic properties of these decays cannot be determined due to the unreconstructable neutrino. The kinematics can however be inferred through the conservation of momentum perpendicular to the flight direction that can be resolved by the LHCb Vertex Locator (VELO). The RF foil is an essential component of the LHCb vertex locator (VELO), separating the secondary vacuum of the VELO from the primary vacuum of the LHC. The foil protects the VELO modules from beam induced effects such as RF waves, and protects the LHC vacuum from hardware effects such as outgassing. The RF foil contributes to the material budget of the experiment and degrades the quality of tracks resulting in a worsened resolution for the reconstructed production and decay vertices. The phase-II upgrade can greatly improve the performance of semileptonic measurements at LHCb. The additional luminosity provided by the LHC coupled with advances in LHCb’s hardware and detector design will allow us to probe previously unobserved decays, while improving our understanding of decays currently under investigation. Improvements in the VELO design will improve the resolution of production and decay vertices, significantly improving the physics performance of semileptonic measurements. In addition, the removal, or thinning, of the RF foil can allow the resolution of measured vertices to be improved even further, while simultaneously improving background rejection, tracking efficiencies and reducing ghost rates. The physics performance increase, solely from improved resolution on semileptonic kinematics due to the removal of the RF foil is estimated.

Related links:
Workshop on the physics of HL-LHC, and perspectives at HE-LHC
© CERN Geneva

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2017-11-03
14:11
A Future Vertex Locator with Precise Timing for the LHCb Experiment
Reference: Poster-2017-602
Keywords:  LHCb
Created: 2017. -1 p
Creator(s): Mitreska, Biljana

The LHCb experiment is designed to perform high precision measurements of matter-antimatter asymmetries and searches for rare and forbidden decays, with the aim of discovering new and unexpected particles and forces. In 2030 the LHC beam intensity will increase by a factor of 50 compared to current operations. This means increased samples of the particles we need to study, but it also presents experimental challenges. In particular, with current technology it becomes impossible to differentiate the many (>50) separate proton-proton collisions which occur for each bunch crossing. A Monte Carlo simulation was developed to model the operation of a silicon pixel vertex detector surrounding the collision region at LHCb, under the conditions expected after 2030, after the second upgrade of the Vertex Locator (VELO). The main goal was studying the effect of adding '4D' detectors which save high-precision timing information, in addition to the usual three spatial coordinates, as charged particles pass through them. With the additional information on the particle timing, it is possible to separately reconstruct the individual 50+ collisions, allowing the next generation of high-precision measurements to be made at the LHCb.

Related links:
Workshop on the physics of HL-LHC, and perspectives at HE-LHC
© CERN Geneva

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2017-10-25
18:39
Single-Bunch Stability With Direct Space Charge
Reference: Poster-2017-601
Keywords:  PyHEADTAIL  Numerical Simulations  Accelerator Physics  Collective Effects  LHC  Impedances  TMCI  Head-tail instability  Space charge
Created: 2017. -1 p
Creator(s): Oeftiger, Adrian

Previous studies have shown the suppressing effect of direct space charge on impedance-driven head-tail instabilities. The present work investigates transverse stability for the HL-LHC scenario based on our macro-particle simulation tool PyHEADTAIL using realistic bunch distributions. The impact of selfconsistent modelling is briefly discussed for non-linear space charge forces. We study how space charge pushes the instability threshold for the transverse mode coupling instability (TMCI) occurring between mode 0 and -1. Next we consider finite chromaticity: in absence of space charge, the impedance model predicts head-tail instabilities. For a selected case below TMCI threshold at Q0 = 5, we demonstrate the stabilising effect of space charge. Finally, we compare simulation results to past LHC measurements.

Related links:
ICFA mini-workshop on Impedances and Beam Instabilities in Particle Accelerators
© CERN Geneva

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2017-09-29
19:03
Extending the search for high-energy muon neutrinos from GRBs with ANTARES
Reference: Poster-2017-598
Keywords:  ANTARES  point-like sources  GRBs  neutrinos  hadronic emission
Created: 2017. -1 p

Gamma-ray bursts (GRBs) are transient sources, potential sites of cosmic-rays acceleration: they are expected to produce high-energy neutrinos in pγ interactions through the decay of charged mesons, thus they constitute promising targets for neutrino telescopes. A search for muon neutrinos from GRBs using 9 years of ANTARES data is here presented, assuming particle acceleration at internal shocks, as expected in the fireball model.

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2017-09-27
15:08
ALICE COLLABORATION - POSTER BOARDS
COLLABORATION ALICE - POSTER

Reference: Poster-2017-597
Created: 2017. -1 p
Creator(s): Gouriou, Nathalie

ALICE

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2017-09-26
16:51
Pressure Profile in the experimental area of FCC-hh and FCC-ee calculated by an analytical code
Reference: Poster-2017-596
Keywords:  FCC simulation  analytical method  vacuum  computer code  PyVasco
Created: 2017. -1 p
Creator(s): Aichinger, Ida

Ultra high vacuum in the beam pipe is a basic requirement for the Future Circular Colliders (FCC). The dimension of the FCC and the high energy of the particles will make this requirement challenging. Simulations that predict the vacuum quality due to material and beam induced effects will allow to evaluate different designs and to choose an optimal solution. The mathematical model behind the simulations will be shown. Four coupled differential equations describe the mass conservation of the residual gas particles in the beam pipe. The sinks include all kind of distributed and local pumping. The sources are caused by synchrotron radiation, electron clouds, thermal outgassing and ion-induced desorption. The equation system is solved by an analytical method. This requires a transformation to first order equations for which a general valid solution exists. Adding a particular solution and the inclusion of appropriate boundary conditions define the solution function. The big advantage here is that an analytical simulation delivers fast results over large systems. The model has been implemented in a Python environment. It has been cross checked with programs like VASCO and MolFlow. Additionally, data obtained from the Large Hadron Collider’s (LHC) gauges were compared to the simulation output. This validates the program and gives trust to produce accurate vacuum forecasts for the FCC. Finally, simulations will be shown for the hadron-hadron collider FCC-hh. Possible designs will be evaluated for the long straight sections including an interaction point.

© CERN Geneva

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2017-08-29
09:14
Real-time alignment and reconstruction : performance and recent developments at the LHCb experiment
Reference: Poster-2017-595
Created: 2017. -1 p
Creator(s): Sokoloff, Michael David; Dziurda, Agnieszka; Grillo, Lucia

Pending.

Related links:
LHCb poster
© CERN Geneva

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2017-08-29
09:06
Machine learning based global particle indentification algorithms at LHCb experiment
Reference: Poster-2017-594
Created: 2017. -1 p
Creator(s): Derkach, Denis; Hushchyn, Mikhail; Likhomanenko, Tatiana; Rogozhnikov, Aleksei; Ratnikov, Fedor

One of the most important aspects of data processing at LHC experiments is the particle identification (PID) algorithm. In LHCb, several different sub-detector systems provide PID information: the Ring Imaging CHerenkov (RICH) detector, the hadronic and electromagnetic calorimeters, and the muon chambers. To improve charged particle identification, several neural networks including a deep architecture and gradient boosting have been applied to data. These new approaches provide higher identification efficiencies than existing implementations for all charged particle types. It is also necessary to achieve a flat dependency between efficiencies and spectator variables such as particle momentum, in order to reduce systematic uncertainties during later stages of data analysis. For this purpose, "flat” algorithms that guarantee the flatness property for efficiencies have also been developed. This talk presents this new approach based on machine learning and its performance.

Related links:
LHCb poster
© CERN Geneva

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2017-07-24
10:10
Publication Life Cycle at CERN Document Server
Reference: Poster-2017-593
Keywords:  Open Repositories  Invenio  CDS
Created: 2017. -1 p
Creator(s): Witowski, Sebastian; Gonzalez Lopez, Jose Benito; Costa, Flavio; Gabancho, Esteban; Marian, Ludmila [...]

This presentation guides listeners through all the stages of publication life cycle at CERN Document Server, from the ingestion using one of the various tools, through curation and processing, until the data is ready to be exported to other systems. It describes different tools that we are using to curate the incoming publications as well as to further improve the existing data on CDS. The second part of the talk goes through various challenges we have faced in the past and how we are going to overcome them in the new version of CDS.

Related links:
Open Repositories
© CERN Geneva

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Open Days 2013 Posters (58)