515664 research outputs found
Sort by
Recent flow and correlation measurements from ATLAS in Pb+Pb collisions
No full textThis proceeding report on ATLAS measuremnt of and flow coefficients for charged particles produced in \mbox{Pb+Pb} collisions at ~TeV collected with the ATLAS detector at the LHC. The and are obtained for high , 1--400~GeV and Pb+Pb centrality, 0--60\%. Two methods, the scalar product and multi-particle cumulants, were used to probe sensitivity to event-by-event fluctuations and non-flow effects. Positive values of and are observed up to a ~GeV and 25~GeV respectively. As jets are the primary source of high particles, the measurement is sensitive to jets' interaction with QGP and in particular to the jets' QGP path-dependent energy loss
High perveance electron gun with controllable current density
No full textThe possibility of controlling the electron current density in an EBIS without changing the actual beam current looks very attractive because it allows to maximize the ion intensity. Our previous publications [1,2] describe a method of controlling the electron cyclotron motion and non-adiabatic electron gun with variable current density. The gun design [2] requires an adjustment of the electron energy before the non-adiabatic element, in this case an iron ring. Our next step was to design an electron gun, which does not need such adjustment while still generating a laminar electron beam in a wide range of currents and densities, a so-called “broadband” electron gun. Furthermore, we aimed to double the perveance of the gun, to avoid beam retardation in the trapping region to attain the desired space charge capacity. To realize the broadband electron gun, we used an iron ring as a non-adiabatic element to create a modest local magnetic field modification. Even though this non-adiabatic magnetic field does not eliminate the beam oscillations completely, the result is sufficient for the electron beam to penetrate the magnetic mirror. Moreover, this non-adiabatic field configuration appears to reduce the amplitude of the cyclotron motion in a wide range of beam parameters (density, energy and current). In this paper we present the computer simulations of this broadband electron gun
Results of femtoscopic correlations at CMS
No full textThe two particle correlations as a function of relative momenta of identified hadrons involving KS0 and Λ, and Λ¯ are measured in PbPb collisions at sNN=5.02TeV with the data samples collected by the CMS experiment at the LHC. Such correlations are sensitive to the quantum statistics and possible final state interactions between the particles. The source radii are extracted from KS0KS0 correlations in different centrality regions and found to decrease from central to peripheral collisions. The strong interaction scattering parameters are extracted from ΛKS0⊕Λ¯KS0 and ΛΛ⊕Λ¯Λ¯ correlations using the Lednicky–Lyuboshits model, and compared with other experimental and theoretical results. In addition, for the first time, we present results for the source radii of charged hadrons considering the L’evy type source distributions in PbPb collisions at sNN=5.02TeV
2025 CERN openlab Certificate Ceremony - Disposable Camera
No full text2025 CERN openlab certificate ceremony through the summer students perspective using a disposable camera with pixel/computing/gaming effects
Searches for electroweak production of supersymmetric particles with the ATLAS detector
No full textThe direct production of electroweak SUSY particles, including sleptons, charginos, and neutralinos, is a particularly interesting area with connections to dark matter and the naturalness of the Higgs mass. The small production cross-sections and challenging experimental signatures, often involving compressed spectra, lead to difficult searches. This talk will highlight the most recent results of searches performed by the ATLAS experiment for supersymmetric particles produced via electroweak processes, including analyses targeting small mass splittings between SUSY particles, and including both in R-parity-conserving and R-parity-violating scenarios. Recent results involving the combination of searches are also presented
An Interferometric Multi-Sensor Absolute Distance Measurement System for Use in Harsh Environments
No full textFourier transform-based frequency sweeping interferometry (FT-FSI) is an interferometric technique that enables absolute distance measurement by detecting the beat frequencies from the interference of reflected signals. This method allows robust, simultaneous distance measurements to multiple targets and is largely immune to variations in the reflected optical signal intensity. As a result, FT-FSI maintains accuracy even when measuring reflectors with low reflectance. FT-FSI has recently been integrated into the full remote alignment system (FRAS) developed for the High-Luminosity Large Hadron Collider (HL-LHC) project at CERN. Designed to operate in harsh environments with electromagnetic interference, ionizing radiation and cryogenic temperatures, FRAS employs FT-FSI for the precise monitoring of the alignment of accelerator components. The system includes specialized interferometers and a range of sensors, including inclinometers, distance sensors, and leveling sensors. This paper presents a comprehensive review of the challenges associated with remote measurement and monitoring systems in harsh environments such as those of particle accelerators. It details the development and validation of the FT-FSI-based measurement system, emphasizing its critical role in enabling micrometric alignment accuracy. The developments and results presented in this work can be readily translated to other demanding metrology applications in harsh environments
The Phase-1 Upgrade of the ATLAS level-1 calorimeter trigger
No full textThe ATLAS level-1 calorimeter trigger is a custom-built hardware system that identifies events containing calorimeter-based physics objects, including electrons, photons, taus, jets, and missing transverse energy. In Run 3, L1Calo has been upgraded to process higher granularity input data. The new trigger comprises several FPGA-based feature extractor modules, which process the new digital information from the calorimeters and execute more sophisticated trigger algorithms. The design of the system will be presented along with an analysis of the improved performance of the upgrade in the increasingly challenging Run-3 LHC pile-up environment