# LHCb Posters

Ultimi arrivi:
2022-12-01
16:12
LHCb - Simulation studies for gas injection into the SMOG2 storage cell at LHCb
 Reference: Poster-2022-1083 Created: 2022. -1 p Creator(s): Lucarelli, Chiara The LHCb experiment started during Run 2 a pioneering fixed-target program studying the collisions between LHC protons and gas targets injected into the LHC beam pipe through a system called SMOG. Since the gas was free to spread into the whole beam pipe of LHCb, only noble gases at low pressure where injectable. In the last few years, LHCb went through a complete upgrade of its detectors in preparation for LHC Run 3. In this context, the SMOG apparatus has been upgraded to SMOG2, introducing a storage cell that better confines the gas, allowing higher luminosity with the same injected gas flow and, potentially, the injection of non-noble gases, like Hydrogen and Deuterium. The impact on the performance of the NEG film, the coating that prevents surface emission phenomena when it is hit with accelerated electrons or ions, due to the non-noble gases flowing from the storage cell into the beam pipe must be carefully evaluated before injecting in order to set realistic limits to the flux and injection time; moreover, an accurate simulation of the gas profile inside the storage cell and its flow into the VELO RF foil is fundamental to the luminosity measurement, to take into account any deviation from the ideal profile due to the real geometry and injection system. This poster presents the first results of the gas flow simulation for hydrogen; the results show that the impact on the NEG coating after injecting Hydrogen for 100 hours with an average pressure of 1 × 10−5 mbar in the storage cell is well within the safety limits. A first comparison between the predicted longitudinal gas profile and the one observed in data during the first operation of SMOG2 is also presented. Related links:Conference 12th LHC students poster session © CERN Geneva Access to files

2022-12-01
16:07
LHCb - Measuring the CKM Angle γ Using B0 → DK+π− Decays at LHCb
 Reference: Poster-2022-1082 Created: 2022. -1 p Creator(s): Wiederhold, Aidan Richard; Shimizu, Yuya A measurement of the CKM angle $\gamma$ using $B^0 \to D K^+ \pi^-$, $D \to (K_S^0 h^+ h^-, h^+ h^-, h^+ h^- h^+ h^-)$ decays with $h=K, \pi$ is presented. A simultaneous binned fit is performed on all decays in both the B and D-decay phase space to optimise sensitivity to $\gamma$. Binned population distribution and strong-phase parameters are measured for the first time in the B-decay phase space. Current progress is described alongside preliminary background-inclusive pseudo-experiment study results to estimate the expected statistical sensitivity to $\gamma$. Related links:Conference 12th LHC students poster session © CERN Geneva Access to files

2022-11-15
09:27
LHCb - Quality assurance of the LHCb Simulation
 Reference: Poster-2022-1081 Created: 2022. -1 p Creator(s): Popov, Dmitry Monte Carlo simulation is a vital tool for all physics programmes of particle physics experiments. Their accuracy and reliability in reproducing detector response is of the utmost importance. For the LHCb experiment, which is embarking on a new data-take era with an upgraded detector, a full suite of verifications has been put in place for its simulation software to ensure the quality of the samples produced. The chain of tests exploits the LHCb infrastructure for software quality control. In this contribution we will describe the procedure and the tests that have been put in place. First-level verifications are performed as soon as new software is submitted for integration in the LHCb GitLab repository. They range from Continous Integration (CI) tests to, so called, 'nightlies': short jobs run overnight to verify the integrity of the software. More in-depth performance and regression tests are carried with dedicated infrastructure (LHCbPR), which compares samples of O(1000) events. Simulation data quality shifters look for anomalies and alert the authors in the case of unexpected changes. Work is also in progress to enable the automatic verification of important variable distributions from a small number of simulated events before the whole production is launched. Related links:21st International Workshop on Advanced Computing and Analysis Techniques in Physics Research © CERN Geneva Access to files

2022-11-14
10:24
LHCb - Quantum Computing Applications at LHCB
 Reference: Poster-2022-1080 Keywords:  LHCb Created: 2022. -1 p Given the recent developments and successes, Quantum Computing (QC) has seen a tremendous increase in relevance and interest. Particularly in the last years, QC algorithms have been developed to study their use in solving typical problems in High Energy Physics. In this poster, we present the recent QC applications to jet tagging and track reconstruction currently pursued by the “Data Processing and Analysis” project at the LHCb experiment. A recently published paper presents an application of Quantum Machine Learning to the identification of 𝑏-jets at the LHCb: a 16-qubit Variational Quantum Classifier trained on a noiseless quantum simulator has been used to distinguish 𝑏-jets from 𝑏¯-jets using the particle substructure of the jets. A similar model is currently being developed for 𝑏-jet versus 𝑐-jet classification, with the possibility of deploying these models on the IBM Q quantum computers. Focusing on track identification, the particles trajectories can be seen as a minimum for a suitable Ising-like Hamiltonian, and solved as a minimization problem. Two approaches based on quantum algorithms are currently under study: the first one involves the use of the Quantum Approximate Optimization Algorithm, solving track reconstruction as a combinatorial optimization problem; the second one uses the framework of Quantum Hopfield neural networks and the Harrow-Hassidim-Lloyd algorithm for solving linear systems of equations, mapping the track reconstruction task into a quantum linear algebra problem. Related links:International Conference on Quantum Technologies for High-Energy Physics (QT4HEP22) © CERN Geneva Access to files

2022-10-28
15:27
LHCb - Quality assurance of the LHCb Simulation
 Reference: Poster-2022-1079 Keywords:  LHCb Created: 2022. -1 p Creator(s): Popov, Dmitry Monte Carlo simulation is a vital tool for all physics programmes of particle physics experiments. Their accuracy and reliability in reproducing detector response is of the utmost importance. For the LHCb experiment, which is embarking on a new data-take era with an upgraded detector, a full suite of verifications has been put in place for its simulation software to ensure the quality of the samples produced. The chain of tests exploits the LHCb infrastructure for software quality control. In this contribution we will describe the procedure and the tests that have been put in place. First-level verifications are performed as soon as new software is submitted for integration in the LHCb GitLab repository. They range from Continous Integration (CI) tests to, so called, 'nightlies': short jobs run overnight to verify the integrity of the software. More in-depth performance and regression tests are carried with dedicated infrastructure (LHCbPR), which compares samples of O(1000) events. Simulation data quality shifters look for anomalies and alert the authors in the case of unexpected changes. Work is also in progress to enable the automatic verification of important variable distributions from a small number of simulated events before the whole production is launched. Related links:Conference ACAT 2022 © CERN Geneva Access to files

2022-10-28
15:18
LHCb-Lamarr: LHCb ultra-fast simulation based on machine learning models
 Reference: Poster-2022-1078 Keywords:  LHCb Created: 2022. -1 p Creator(s): Barbetti, Matteo About 90% of the computing resources available to the LHCb experiment has been spent to produce simulated data samples for Run 2 of the Large Hadron Collider. The upgraded LHCb detector will operate at much-increased luminosity, requiring many more simulated events for the Run 3. Simulation is a key necessity of analysis to interpret data in terms of signal and background and estimate relevant efficiencies. The amount of simulation required will far exceed the pledged resources, requiring an evolution in technologies and techniques to produce simulated data samples. In this conference contribution, we discuss Lamarr, a Gaudi-based framework to speed-up the simulation production parametrizing both the detector response and the reconstruction algorithms of the LHCb experiment. Deep Generative Models powered by several algorithms and strategies are employed to effectively parameterize the high-level response of the single components of the LHCb detector, encoding within neural networks the experimental errors and uncertainties introduced in the detection and reconstruction phases. Where possible, models are trained directly on real data, statistically subtracting any background components through the application of weights. Embedding Lamarr in the general LHCb simulation framework (Gauss) allows to combine its execution with any of the available generators in a seamless way. The resulting software package enables a simulation process completely independent of the detailed simulation used to date. Related links:Conference ACAT 2022 © CERN Geneva Access to files

2022-08-10
14:25
LHCb New measurements in fixed-target collisions at LHCb
 Reference: Poster-2022-1077 Created: 2022. -1 p Creator(s): Okamura, Shinichi The LHCb spectrometer has the unique capability to function as a fixed-target experiment by injecting gas into the LHC beampipe while proton or ion beams are circulating. The resulting beam+gas collisions cover a poorly explored energy range that is above previous fixed-target experiments, but below the top RHIC energy for AA collisions. Here we present new results on antiproton and charm production from $p$He, $p$Ne, and PbNe fixed-target collisions at LHCb. Comparisons with various theoretical models of particle production and transport through the nucleus will be discussed. Related links:LHCb poster © CERN Geneva Access to files

2022-07-14
15:39
Probe for Luminosity Measurement at LHCb
 Reference: Poster-2022-1076 Created: 2022. -1 p Creator(s): Spedicato, Eugenia A new detector capable of measuring the LHC luminosity has been installed at the interaction point of LHCb. It is named Probe for LUminosity MEasurement - PLUME. This detector is undergoing commissioning and will operate throughout LHC Run 3. It will enable real time monitoring of beam condition parameters such as luminosity, number of visible interactions per bunch crossing, background; it will cross-check the LHC filling scheme in real time, and contribute to the centrality determination for the LHCb fixed-target programme. The detector is based on the detection of Cherenkov light produced in quartz material by charged particles coming upstream from the LHCb collision region. PLUME is charged with providing both online and offline measurements with a time response that can be as fast as a fraction of a second, and it will ensure the vital luminosity-levelling procedure at LHCb and act as real-time alarm for LHC. © CERN Geneva Access to files

2022-07-14
15:34
The NTuple Wizard An NTuple production service for accessing LHCb Open Data
 Reference: Poster-2022-1075 Created: 2014. -1 p Creator(s): O'Neil, Ryunosuke Making the large datasets collected at the LHC accessible to the public is a considerable challenge given the complexity and volume of data. Yet to harness the full scientific potential of the facility, it is essential to enable meaningful access to the data by the broadest physics community possible. Here we present a tool, the LHCb NTuple Wizard, which leverages the existing computing infrastructure available to the LHCb collaboration in order to enable third-party users to request derived data samples in the same format used in LHCb physics analysis. An intuitive web interface allows for the discovery of accessible datasets and guides the user through the process of specifying a request for producing NTuples: an ordered set of particle or decay candidates cataloging measured quantities chosen by the user. Issues of computer security and access control arising from offering this service are addressed within its design, while still offering datasets suitable for scientific research through the CERN Open Data Portal. © CERN Geneva Access to files

2022-06-17
14:48
New measurements in fixed-target collisions at LHCb
 Reference: Poster-2022-1074 Created: 2022. -6 p Creator(s): Sellam, Sara The LHCb spectrometer has the unique capability to function as a fixed-target experiment by injecting gas into the LHC beampipe while proton or ion beams are circulating. The resulting beam+gas collisions cover an unexplored energy range that is above previous fixed-target experiments, but below the top RHIC energy for AA collisions. Here we present new results on antiproton and charm production from pHe, pNe, and PbNe fixed-target collisions at LHCb. Comparisons with various theoretical models of particle production and transport through the nucleus will be discussed. © CERN Geneva Access to files