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First neon-neon collisions recorded by the ATLAS Experiment
No full textEvent displays of a neon-neon collisions recorded by the ATLAS experiment on 8 July 2025, with a centre-of-mass energy per nucleon pair of 5.36 TeV
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 total 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
A Prototype Hybrid Mode Cavity for Heterodyne Axion Detection
No full textIn the heterodyne approach to axion detection, axion dark matter induces transitions between two modes of a microwave cavity, resulting in a parametrically enhanced signal power. We describe the fabrication and characterization of a prototype normal conducting cavity specifically optimized for heterodyne detection. Corrugations on the cavity walls support linearly polarized hybrid modes which maximize the signal power while strongly suppressing noise. We demonstrate tuning mechanisms which allow one mode's frequency to be scanned across a 4 MHz range, while suppressing cross-coupling noise by at least 80 dB. A future superconducting cavity with identical geometry to our prototype would have the potential to probe orders of magnitude beyond astrophysical bounds
The LHC as Lepton-Proton Collider: Search for the Resonant Production of Leptoquarks
No full textSearches for leptoquarks are a key component of the LHC program probing physics beyond the Standard Model. These hypothetical particles couple to a lepton and a quark and are predicted by many extensions of the Standard Model such as Grand Unified Theories. The existing leptoquark searches at the LHC currently mostly consider production modes via quark and/or gluon interactions. However, the small but non-zero lepton content of the proton allows to also study the significantly less explored s-channel, resonant leptoquark production. This production mode gives rise to lepton-plus-jet signatures. Thus, leptoquarks would emerge as distinctive peaks over the smoothly falling Standard Model background in the invariant mass spectrum of the lepton-plus-jet system. The poster will give an overview of the first ATLAS analysis searching for this new process in four separate final states involving light leptons plus either jets originating from light quarks or from bottom quarks. It will especially focus on the details of the search for the electron-plus-jet signature. The general analysis strategy and the results of this search will be discussed. Probing the resonant, s-channel production shows competitive and complementary sensitivity to existing searches for e.g. the pair production of leptoquarks, particularly for leptoquarks with a high coupling to fermions. To maximize the sensitivity reach, the full ATLAS Run2 dataset is combined with the partial Run3 dataset of 2022 and 2023 for this search
Performance, Calibration and Optics Robustness of the ATLAS Tile Calorimeter
No full textThe Tile Calorimeter (TileCal) is a sampling hadronic calorimeter covering the central region of the ATLAS experiment, operating at the Large Hadron Collider (LHC) at CERN. TileCal is made of steel as absorber and plastic scintillators as active medium. The scintillators are read-out by wavelength shifting fibres coupled to photomultiplier tubes (PMTs). The analogue signals from the PMTs are amplified, shaped, digitized by sampling the signal every 25 ns and stored on detector until a trigger decision is received. The TileCal front-end electronics reads out the signals produced by about 10000 channels measuring energies ranging from about 30 MeV to about 2 TeV. During LHC runs, high-momentum isolated muons have been used to study and validate the electromagnetic scale, while hadronic response has been probed with isolated hadrons. The calorimeter time resolution has been studied with multi-jet events. Besides, the integrated cells signals from minimum bias events provide auxiliary information on the response stability from the whole detector during proton-proton collisions. The calibration systems are used to estimate the radiation damage suffered by the active media of the detector, the scintillators and the wavelengths shifting optical fibres that collect the light into the photodetectors readout. First results using early LHC Run-3 data will be shown. A summary of the performance results, including the calibration, stability, absolute energy scale, uniformity, time resolution and the plastic scintillators light output loss due to integrated dose will be presented
Electromagnetic energy calibration of the SoLid detector with horizontal muons
No full textSoLid is a neutrino experiment at very-short baselinesearching for active-to-sterile oscillations of reactorantineutrinos. The detection principle is based on the pairing oftwo types of solid scintillators: polyvinyl toluene and Li:ZnS(Ag), which is a new technology used in this field ofPhysics. In addition to good neutron-gamma discrimination, thissetup allows the detector to be highly segmented; the basicdetection unit is a 5 cm cube. High segmentation provides numerousadvantages including precise localisation of the Inverse Beta Decay(IBD) products, the derivation of an antineutrino energy estimatorbased on the isolated positron energy, and a powerful backgroundreduction tool that relies on the topological signature of thesignal. Finally, the system is read out by a network ofwavelength-shifting fibres coupled to photosensors. A relativeelectromagnetic calibration is performed with horizontal cosmicmuons. This source poses the simplest calibration problem in which asingle detection unit is involved. In addition, large muon energydeposits allow us to perform a calibration at the most detailedlevel (i.e. per fibre) and to accurately define the fraction ofenergy escaping to neighbouring detection cells. A statisticalprecision at the sub-percent level is reached. The paper alsodiscusses two methods to calibrate the absolute energy scale andpresents their implementation and results. The first method relieson horizontal muons, though the precision is limited to around 10%because of the uncertainty in the energy distribution of suchmuons. A novel, alternative method based on the radioactiveamericium-beryllium source is proposed. It takes advantage of theelectron-positron pair-production process and provides a calibrationpoint at 3.4 MeV (i.e. in the core of the IBD positronspectrum). The paper is concluded with various cross-check includinga determination of the energy spectrum of the standard cosmogenicbackground candle: B.SoLid is a neutrino experiment at very-short baseline searching for active-to-sterile oscillations of reactor antineutrinos. The detection principle is based on the pairing of two types of solid scintillators: polyvinyl toluene and Li:ZnS(Ag), which is a new technology used in this field of Physics. In addition to good neutron-gamma discrimination, this setup allows the detector to be highly segmented; the basic detection unit is a 5 cm cube. High segmentation provides numerous advantages including precise localisation of the Inverse Beta Decay (IBD) products, the derivation of an antineutrino energy estimator based on the isolated positron energy, and a powerful background reduction tool that relies on the topological signature of the signal. Finally, the system is read out by a network of WLS fibres coupled to photosensors. A relative electromagnetic calibration is performed with horizontal cosmic muons. This source poses the simplest calibration problem in which a single detection unit is involved. In addition, large muon energy deposits allow us to perform a calibration at the most detailed level (i.e. per fibre) and to accurately define the fraction of energy escaping to neighbouring detection cells. A statistical precision at the sub-percent level is reached. The paper also discusses two methods to calibrate the absolute energy scale. The first method relies on horizontal muons, though the precision is limited to around 10% because of the uncertainty in the energy distribution of such muons. A novel, alternative method based on the radioactive AmBe source is proposed. It takes advantage of the electron-positron pair-production process and provides a calibration point at 3.4 MeV (i.e. in the core of the IBD positron spectrum). The paper is concluded with various cross-check including a determination of the energy spectrum of the standard cosmogenic background candle: B
Precision and rare ElectroWeak processes
No full textThis proceeding summarizes recent measurements of electroweak boson and diboson production. The results, based on data from LHC Run 2 at √s = 13 TeV and Run 3 at √s = 13.6 TeV, probe the Standard Model with unprecedented precision. These include inclusive and differential cross- section measurements of W, Z, W Z, WW, and Z Z final states, constraints on Parton Distribution Functions, and interpretations within Effective Field Theories. A consistent picture with theory predictions emerges, laying the groundwork for future precision studie
Heavy flavour production and decay in ATLAS
No full textThis talk will present the recent results from ATLAS experiments on open-charm meson production measurements and various studies of b hadron decays, including the most precise measurement of the lifetime
Status of the ALICE Fast Interaction Trigger in RUN 3
No full textThe Fast Interaction Trigger (FIT)—a hybrid system of three ALICE forward detectors—has participated in each data-taking session since the beginning of LHC Run 3 in July 2022. FIT is essential for ALICE operation and provides the fastest online trigger, measures precision collision time, charged-particle multiplicity and centrality, and determines the online vertex position. It also serves as the primary online luminometer used by the LHC for beam levelling at ALICE