scholarly journals The evolution of the ALICE O2 monitoring system

2020 ◽  
Vol 245 ◽  
pp. 01042
Author(s):  
Adam Wegrzynek ◽  
Gioacchino Vino
Keyword(s):  
Monitoring System ◽  
Fault Tolerant ◽  
Heavy Ion ◽  
Tool Selection ◽  
Alice Experiment ◽  
The Core ◽  
Computing Model ◽  
Ion Collisions ◽  
Software Sensors ◽  
Component Failures

The ALICE Experiment was designed to study the physics of strongly interacting matter with heavy-ion collisions at the CERN LHC. A major upgrade of the detector and computing model (O2, Offline-Online) is currently ongoing. The ALICE O2 farm will consist of almost 1000 nodes enabled to read out and process on-the-fly about 27 Tb/s of raw data. To efficiently operate the experiment and the O2 facility a new monitoring system was developed. It will provide a complete overview of the overall health, detect performance degradation and component failures by collecting, processing, storing and visualising data from hardware and software sensors and probes. The core of the system is based on Apache Kafka ensuring high throughput, fault-tolerant and metric aggregation, processing with the help of Kafka Streams. In addition, Telegraf provides operating system sensors, InfluxDB is used as a time-series database, Grafana as a visualisation tool. The above tool selection evolved from the initial version where collectD was used instead of Telegraf, and Apache Flume together with Apache Spark instead of Apache Kafka.

CHARMONIUM PRODUCTION IN Pb–Pb COLLISIONS AT ALICE: FROM SUPPRESSION TO REGENERATION?

2013 ◽  
Vol 28 (21) ◽  
pp. 1330018 ◽  
Author(s):  
ENRICO SCOMPARIN
Keyword(s):  
Phase Transition ◽  
Cross Sections ◽  
Short Review ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Alice Experiment ◽  
Model Calculations ◽  
Ion Collisions ◽  
Quark Production ◽  
History Of

Heavy quarkonium states are considered as one of the key observables for the study of the phase transition from a system made of hadrons towards a Quark–Gluon Plasma (QGP). In the last 25 years, experiments at CERN and Brookhaven have studied collisions of heavy ions looking for a suppression of charmonia/bottomonia, considered as a signature of the phase transition. After an introduction to the main concepts behind these studies and a short review of the SPS and RHIC results, I will describe the results obtained in Pb – Pb collisions by the ALICE experiment at the LHC. The ALICE findings will be critically compared to those of lower energy experiments, to CMS results, and to model calculations. The large cross-sections for heavy-quark production at LHC energies are expected to induce a novel production mechanism for charmonia in heavy-ion collisions, related to a recombination of [Formula: see text] pairs along the history of the collision and/or at hadronization. The occurrence of such a process at the LHC will be discussed. Finally, prospects for future measurements will be shortly addressed.

THE ALICE EXPERIMENT AT CERN LHC: STATUS AND FIRST RESULTS

2011 ◽  
Vol 26 (03n04) ◽  
pp. 517-522
Author(s):  
◽  
ERMANNO VERCELLIN
Keyword(s):  
Data Analysis ◽  
Cosmic Rays ◽  
Dense Matter ◽  
Heavy Ion ◽  
Short Description ◽  
Alice Experiment ◽  
Ion Collisions ◽  
Physics Program ◽  
Accelerate Proton ◽  
First Results

The ALICE experiment is aimed at studying the properties of the hot and dense matter produced in heavy-ion collisions at LHC energies. In the first years of LHC operation the ALICE physics program will be focused on Pb - Pb and p - p collisions. The latter, on top of their intrinsic interest, will provide the necessary baseline for heavy-ion data. After its installation and a long commissioning with cosmic rays, in late fall 2009 ALICE participated (very successfully) in the first LHC run, by collecting data in p - p collisions at c.m. energy 900 GeV. After a short stop during winter, LHC operations have been resumed; the machine is now able to accelerate proton beams up to 3.5 TeV and ALICE has undertaken the data taking campaign at 7 TeV c.m. energy. After an overview of the ALICE physics goals and a short description of the detector layout, the ALICE performance in p - p collisions will be presented. The main physics results achieved so far will be highlighted as well as the main aspects of the ongoing data analysis.

Sudden increase in the degrees of freedom in dense QCD matter

2021 ◽  
Author(s):  
Aditya Nath Mishra ◽  
Guy Paić ◽  
C. Pajares ◽  
R. P. Scharenberg ◽  
B. K. Srivastava
Keyword(s):  
Charged Particle ◽  
Energy Density ◽  
Heavy Ion Collisions ◽  
Degrees Of Freedom ◽  
Initial Temperature ◽  
Heavy Ion ◽  
Particle Multiplicity ◽  
Sudden Increase ◽  
Alice Experiment ◽  
Ion Collisions

In this paper, we analyzed charged particle transverse momentum spectra in high multiplicity events in proton–proton and nucleus–nucleus collisions at LHC energies from the ALICE experiment using the color string percolation model (CSPM). The color reduction factor and associated string density parameters are extracted for various multiplicity classes in [Formula: see text] collisions and centrality classes for heavy-ion collisions at various LHC energies to study the effect of collision geometry and collision energy. These parameters are used to extract the thermodynamical quantities temperature and the energy density of the hot nuclear matter. A universal scaling is observed in initial temperature when studied as a function of charged particle multiplicity scaled by transverse overlap area. From the measured initial energy density [Formula: see text] and the initial temperature T, a dimensionless quantity [Formula: see text] is constructed which is used to obtain the degrees of freedom (DOF) of the deconfined phase. A two-step behavior and a sudden increase in DOF of [Formula: see text]47 for the ideal gas, above the hadronization temperature (T [Formula: see text] 210[Formula: see text]MeV), are observed in case of heavy-ion collisions at LHC energies.

scholarly journals Correlation of Heavy and Light Flavors in Simulations

Universe ◽  
2019 ◽  
Vol 5 (5) ◽  
pp. 118
Author(s):  
Eszter Frajna ◽  
Róbert Vértesi
Keyword(s):  
Large Hadron Collider ◽  
Heavy Ion Collisions ◽  
Hadron Collider ◽  
D Meson ◽  
Heavy Ion ◽  
High Energy ◽  
Secondary Vertex ◽  
Alice Experiment ◽  
Ion Collisions ◽  
B Quarks

The ALICE experiment at the Large Hadron Collider (LHC) ring is designed to study the strongly interacting matter at extreme energy densities created in high-energy heavy-ion collisions. In this paper we investigate correlations of heavy and light flavors in simulations at LHC energies at mid-rapidity, with the primary purpose of proposing experimental applications of these methods. Our studies have shown that investigating the correlation images can aid the experimental separation of heavy quarks and help understanding the physics that create them. The shape of the correlation peaks can be used to separate the electrons stemming from b quarks. This could be a method of identification that, combined with identification in silicon vertex detectors, may provide much better sample purity for examining the secondary vertex shift. Based on a correlation picture it is also possible to distinguish between prompt and late contributions to D meson yields.

scholarly journals JET AND HIGH PT MEASUREMENTS WITH THE ALICE EXPERIMENT

2011 ◽  
Vol 20 (07) ◽  
pp. 1533-1538
Author(s):  
◽  
CHRISTIAN KLEIN-BÖSING
Keyword(s):  
Particle Production ◽  
Center Of Mass ◽  
Heavy Ion ◽  
First Year ◽  
Alice Experiment ◽  
Elementary Reactions ◽  
Ion Collisions ◽  
New Energy ◽  
First Results ◽  
Medium Influence

Since the beginning of 2010 the LHC provides p + p collisions at the highest center of mass energies to date, allowing to study high p T particle production and jet properties in a new energy regime. For a clear interpretation and the quantification of the medium influence in heavy-ion collisions on high p T observables a detailed understanding of these elementary reactions is essential. We present first results on the observation of jet-like properties with the ALICE experiment and discuss the performance of jet reconstruction in the first year of data taking.

scholarly journals Heavy-Flavor Measurements with the ALICE Experiment at the LHC

Universe ◽  
2019 ◽  
Vol 5 (5) ◽  
pp. 130 ◽  
Author(s):  
Róbert Vértesi
Keyword(s):  
Heavy Ion ◽  
Gluon Plasma ◽  
Heavy Quarks ◽  
Heavy Flavor ◽  
Successful Completion ◽  
Alice Experiment ◽  
Ion Collisions ◽  
State Of Matter ◽  
Heavy Flavor Quarks ◽  
Dense State

Heavy quarks (charm and beauty) are produced early in the nucleus–nucleus collisions, and heavy flavor survives throughout the later stages. Measurements of heavy-flavor quarks thus provide us with means to understand the properties of the Quark–Gluon Plasma, a hot and dense state of matter created in heavy-ion collisions. Production of heavy-flavor in small collision systems, on the other hand, can be used to test Quantum-chromodynamics models. After a successful completion of the Run-I data taking period, the increased luminosity from the LHC and an upgraded ALICE detector system in the Run-II data taking period allows for unprecedented precision in the study of heavy quarks. In this article we give an overview of selected recent results on heavy-flavor measurements with ALICE experiments at the LHC.

scholarly journals Recent results from the ALICE Experiment at LHC

2018 ◽  
Vol 191 ◽  
pp. 01004
Author(s):  
Catalin Ristea
Keyword(s):  
System Size ◽  
Heavy Ion ◽  
Dense Medium ◽  
Production Flow ◽  
Alice Experiment ◽  
Final State ◽  
Proton Proton ◽  
Ion Collisions ◽  
Flow Phenomena ◽  
Nuclear Modification Factors

ALICE (A Large Ion Collider Experiment) at the LHC performed high statistics measurements in Pb-Pb collisions at the top LHC energy, complemented with large recent reference datasets in elementary proton-proton collisions at the same energy. Elementary pp collisions are serving as baseline for testing QCD properties and allow the study of the changes induced by the hot and dense medium produced in heavy ion collisions. Key observables like nuclear modification factors, jet production, flow phenomena and spectra for identified particles, related to the different stages of collision evolution, are presented and compared with the most recent results from p-Pb and Xe-Xe collisions, thus allowing to probe both initial cold nuclear matter and final state effects, combined with the system size dependence of the measurements.

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