CERN Accelerating science

Posters

Ostatnio dodane:
2014-04-17
11:24
LHCb : Measurement of the $B_c$ Lifetime in semileptonic decays at LHCb
Reference: Poster-2014-418
Keywords:  LHCb
Created: 2014. -1 p
Creator(s): Anderlini, Lucio

The lifetime of the $B_c^+$ meson is measured using semileptonic decays having a $J\!/\!\psi$ meson and a muon in the final state. The data, corresponding to an integrated luminosity of $2\mathrm{fb^{-1}}$, are collected by the LHCb detector in $pp$ collisions at a centre-of-mass energy of $8\,\mathrm{TeV}$. The measured lifetime is $$\tau = 509 \pm 8 \pm 12 \mathrm{~fs},$$ where the first uncertainty is statistical and the second is systematic.

Presented at 117th LHCC Meeting - Open Session Geneva, Switzerland 5 - 6 Mar 2014 2014 , (list conference papers) Related links:
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2014-04-15
09:35
A position sensitive silicon detector for AEgIS (Antimatter Experiment: Gravity, Interferometry, Spectroscopy)
Reference: Poster-2014-417
Keywords:  AEḡIS, silicon, antiproton, annihilation, pixel detector, antihydrogen
Created: 2014. -1 p
Creator(s): Gligorova, A

The AEḡIS experiment (Antimatter Experiment: Gravity, Interferometry, Spectroscopy) is located at the Antiproton Decelerator (AD) at CERN and studies antimatter. The main goal of the AEḡIS experiment is to carry out the first measurement of the gravitational acceleration for antimatter in Earth’s gravitational field to a 1% relative precision. Such a measurement would test the Weak Equivalence Principle (WEP) of Einstein’s General Relativity. The gravitational acceleration for antihydrogen will be determined using a set of gravity measurement gratings (Moiré deflectometer) and a position sensitive detector. The vertical shift due to gravity of the falling antihydrogen atoms will be detected with a silicon strip detector, where the annihilation of antihydrogen will take place. This poster presents part of the development process of this detector.

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2014-04-14
19:56
Study and Development of a Laser Based Alignment System
Reference: Poster-2014-416
Created: 2014. -1 p
Creator(s): Stern, G

CLIC (Compact Linear Collider) has tight requirements regarding pre-alignment of beam related components: 10 µm accuracy over a sliding window of 200 m along the 20 km of linac. To perform such an alignment, a new system is proposed combining laser beam as straight line reference and camera/shutter assemblies as sensors. The poster describes the alignment system and shows results regarding laser pointing stability with respect to time, shutter type, distance and environment. These results give a frame for future building and calibrating of sensors.

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2014-04-14
18:33
Benchmark of the SixTrack-Fluka Active Coupling Against the SPS Scrapers Burst Test
Reference: Poster-2014-415
Created: 2014. -1 p
Creator(s): Mereghetti, A; Appleby, R B; Cerutti, F

The SPS scrapers are a key ingredient for the clean injection into the LHC: they cut off halo particles quite close to the beam core (e.g.~3.5 sigma) just before extraction, to minimise the risk for quenches. The improved beam parameters as envisaged by the LHC Injectors Upgrade (LIU) Project required a revision of the present system, to assess its suitability and robustness. In particular, a burst (i.e. endurance) test of the scraper blades has been carried out, with the whole bunch train being scraped at the centre (worst working conditions). In order to take into account the effect of betatron and longitudinal beam dynamics on energy deposition patterns, and nuclear and Coulomb scattering in the absorbing medium onto loss patterns, the SixTrack and Fluka codes have been coupled, profiting from the best of the refined physical models they respectively embed. The coupling envisages an active exchange of tracked particles between the two codes at each turn, and an on-line aperture check in SixTrack, in order to estimate the local cleaning inefficiency of the system. In the framework of the LIU scraper studies, a benchmark between the SixTrack-Fluka coupling and the outcomes of the burst test is being carried out, comparing observables about material damage, beam intensity and losses.

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2014-04-14
16:35
Automated Formal Verification for PLC Control Systems
Reference: Poster-2014-414
Keywords:  PLC  Siemens  Formal Verification  Model Checking  Automata  NuSMV and nuXmv  UPPAAL  BIP
Created: 2014. -1 p
Creator(s): Fernández Adiego, Borja

Programmable Logic Controllers (PLCs) are widely used devices used in industrial control systems. Ensuring that the PLC software is compliant with its specification is a challenging task. Formal verification has become a recommended practice to ensure the correctness of the safety-critical software. However, these techniques are still not widely applied in industry due to the complexity of building formal models, which represent the system and the formalization of requirement specifications. We propose a general methodology to perform automated model checking of complex properties expressed in temporal logics (e.g. CTL, LTL) on PLC programs. This methodology is based on an Intermediate Model (IM), meant to transform PLC programs written in any of the languages described in the IEC 61131-3 standard (ST, IL, etc.) to different modeling languages of verification tools. This approach has been applied to CERN PLC programs validating the methodology.

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2014-04-14
15:34
CLIQ – Coupling-Loss Induced Quench System for Protecting Superconducting Magnets
Reference: Poster-2014-413
Keywords:  Superconducting Magnet  Magnet Protection  CLIQ  Modelling  AC Losses
Created: 2014. -1 p
Creator(s): Ravaioli, E; Datskov, V I; Kirby, G; ten Kate, H H J; Verweij, A P

The recently developed Coupling-Loss-Induced Quench (CLIQ) protection system is a new method for initiating a fast and voluminous transition to the normal state for protecting high energy density superconducting magnets. Upon quench detection, CLIQ is triggered to generate an oscillating current in the magnet coil by means of a capacitive discharge. This in turn introduces a high coupling loss in the superconductor which provokes a quick transition to the normal state of the coil windings. The system is now implemented for the protection of a two meter long superconducting quadrupole magnet and characterized in the CERN magnet test facility. Various CLIQ configurations with different current injection points are tested and the results compared to similar transients lately measured with a not optimized configuration. Test results convincingly show that the newly tested design allows for a more global quench initiation and thus a faster discharge of the magnet energy. Moreover, the performance of CLIQ for reducing the hot spot temperature after a quench is compared to what can be achieved with conventional quench heaters. In addition, the measured transients are reproduced by means of a lumped-element dynamic electro-thermal model developed with Simulink©. After its validation, the model is now in use for simulating various discharges in order to find the optimum CLIQ configuration and operating parameters for the most homogeneous transition to the normal state of the coil windings and hence the lowest hot spot temperature. Finally, the integration of the new CLIQ system with conventional protection systems like quench heaters and energy extraction is thoroughly discussed for incompatibilities and effective synergies.

Presented at 10th International Conference on Web Information Systems and Technologies Barcelona, Spain 3 - 5 Apr 2014 2014 , (list conference papers) Related links:
https://jobs.web.cern.ch/after-selection/info-activities
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2014-04-14
15:24
Space Charge Mitigation by Hollow Bunches
Reference: Poster-2014-412
Keywords:  beam dynamics  space charge  hollow bunches  high luminosity
Created: 2014. -1 p
Creator(s): Oeftiger, AO

To satisfy the requirements of the HL-LHC (High Luminosity Large Hadron Collider), the LHC injector chain will need to supply a higher brightness, i.e. deliver the same transverse beam emittances \epsilon_{x,y} while providing a higher intensity N. However, a larger number of particles per bunch enhances space charge effects. One approach to mitigate the impact of space charge is to change the longitudinal phase space distribution: hollow bunches feature a depleted bunch centre and a densely populated periphery. Thus, the spatial line density maximum is depressed which ultimately decreases the tune spread imposed by space charge. Therefore, a higher intensity can be accepted while keeping the same overall space charge tune shift. 3 different methods to create hollow bunches in the PSBooster are simulated.

Related links:
Doctoral Poster Session 2014
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2014-03-18
16:15
Observation of photon polarization in $B^\pm \to K^\pm\pi^\mp\pi^\pm\gamma$ decays
Reference: Poster-2014-411
Keywords:  Flavor Physics  B Physics  polarization  rare decay
Created: 2014. -1 p
Creator(s): Veneziano, G

A study of the flavor-changing neutral current radiative $B^{\pm} \to K^{\pm}\pi^{\mp}\pi^{\pm}\gamma$ decays performed using data collected in proton-proton collisions with the LHCb detector at $7$ and $8\,$TeV center-of-mass energies is presented. In this sample, corresponding to an integrated luminosity of $3\,\text{fb}^{-1}$, nearly $14\,000$ signal events are reconstructed and selected, containing all possible intermediate resonances with a $K^{\pm}\pi^{\mp}\pi^{\pm}$ final state in the $[1.1, 1.9]$\,GeV/$c^{2}$ mass range. The distribution of the angle of the photon direction with respect to the plane defined by the final-state hadrons in their rest frame is studied in intervals of $K^{\pm}\pi^{\mp}\pi^{\pm}$ mass and the asymmetry between the number of signal events found on each side of the plane is obtained. The first direct observation of the photon polarization in the $b \to s\gamma$ transition is reported with a significance of $5.2\,\sigma$.

Presented at 117th LHCC Meeting - Open Session Geneva, Switzerland 5 - 6 Mar 2014 2014 , (list conference papers) Related links:
LHCb conference poster
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2014-03-17
12:24
Trigger tracking for the LHCb upgrade
Reference: Poster-2014-410
Keywords:  LHCb  trigger  upgrade
Created: 2014. -1 p
Creator(s): Dungs, K

This poster presents a trigger system for the upgraded LHCb detector, scheduled to begin operation in 2020. The proposed trigger system is implemented entirely in software. We show that track reconstruction of a similar quality to that available in the offline algorithms can be performed on the full inelastic pp-collision rate. A track finding efficiency of 98.8% relative to offline can be achieved for good trigger tracks. The CPU time required for this reconstruction is less than 60% of the available budget.

Presented at 117th LHCC Meeting - Open Session Geneva, Switzerland 5 - 6 Mar 2014 2014 , (list conference papers) Related links:
LHCb Conference poster
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2014-03-17
12:11
Measurements of inclusive Z and Z plus D production at $\sqrt{s}=7$ TeV at LHCb
Reference: Poster-2014-409
Keywords:  LHCb  Measurements  inclusive  production
Created: 2014. -1 p
Creator(s): Ronan, W

Measurements of Z boson production provide important tests of the Standard Model as well as being inputs for determining the parton density functions (PDFs) of the proton. Here we examine the inclusive production as well as production in association with D mesons, which can be produced via a double parton scattering mechanism. Datasets of 1 fb$^{-1}$ recorded with the LHCb detector at $\sqrt{s}=7$ TeV are used.

Presented at 117th LHCC Meeting - Open Session Geneva, Switzerland 5 - 6 Mar 2014 2014 , (list conference papers) Related links:
LHCb conference poster
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Open Days 2013 Posters (58)