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No full text- How are LHC experiments and LHC Operations using Emittance scans today
- Is there a preference for early or late scans
- How frequently should they be run
- List improvements that either have been implemented in the analysis since Run II , or are definitely needed (e.g.: BB corrections, all expts), or are being dreamt about (e.g. characterization of long-range BB effects in the scans with trains
Multiple (multi-)strange hadron production in proton-proton collisions at = 5.02 TeV with ALICE at the LHC
No full textThe increased production of strange hadrons in heavy-ion collisions compared to minimum-bias pp collisions has historically been interpreted as one of the earliest signatures of the formation of a deconfined quark-gluon plasma. One of the most significant findings from Run 1 and Run 2 of the LHC is the observation by the ALICE Collaboration of an enhanced production of (multi-)strange to non-strange hadron yields, gradually rising from low-multiplicity to high-multiplicity pp and p–Pb collisions, reaching values close to those measured in peripheral Pb–Pb collisions. Despite these observations, the origin of this phenomenon in small collision systems remains unclear. Furthermore, none of the current QCD-inspired Monte Carlo generators can quantitatively describe the observed behavior. This emphasizes the need for additional experimental data, new observables and theoretical advancements to uncover the microscopic mechanisms driving strangeness enhancement. A deeper understanding of the mechanisms behind strangeness production, and hadronization more in general, could be achieved by measuring the (multi-)strange particle multiplicity distribution (P()). A novel method involving event-by-event count-ing of strange particles offers a promising approach. In this thesis, the first ALICE results of the multiplicity distributions for K, , , , , , and in pp collisions at = 5.02 TeV are presented as a function of charged particle multiplicity. These results provide a unique perspective on the correlation between charged and strange particles’ production. Furthermore, the measurement of P() enables the determination of the average yields of multiplets for each type of strange particle, widening the scope of strangeness production studies beyond average values and enabling the investigation of extreme cases where up to six strange quarks coalesce into hadrons in a single event. Additionally, by comparing hadron combinations with varying and quark compositions but identical total strange () quark content, it becomes possible to isolate the contributions to the enhancement pattern that arise from mechanisms unrelated to strangeness. These findings are compared with state-of-the-art phenomenological models implemented in commonly used Monte Carlo event generators, drastically enhancing the sensitivity to the different processes implemented in each approach. This thesis also provides an overview of the data quality of the MUon IDentifier (MID) during pp and Pb–Pb collisions in Run 3 (2022–2024), with a focus on monitoring the asynchronous quality control
Ion beams requirements for the North Area Experiments post-LS3
No full textThe Super Proton Synchrotron (SPS) delivers ion beams to Experimental Hall North 1 (EHN1) on the CERN Prévessin site typically over a period of four weeks per year. EHN1 is currently hosting one physics experiment using ion beams, the NA61/SHINE experiment approved until Long Shutdown 3 (LS3). For the longer term, proposals based on ion beams of different species and energies have been made. The current status of the study conducted by the CERN Physics Beyond Colliders (PBC) study group in collaboration with the Future Ions Working Group is presented, including considerations on beam requirements and upgrades, schedules and cost, as well as physics potential within the CERN and worldwide landscap
FASER2: Detector Design and Performance
No full textFASER2 is a proposed upgrade to the FASER experiment, and could be hosted in the Forward Physics Facility (FPF) suggested to be 620m to the west of the ATLAS interaction point, in the far-forward region of the LHC collisions. The upgrade involves a significantly enlarged volume compared to FASER, resulting in an increase in reach for various BSM signals of several orders of magnitude and allows sensitivity to models that were previously out of reach, such as Dark Higgs and Heavy Neutral Leptons. The experiment is specifically designed to have sensitivity to long-lived particles (LLPs) produced by rare meson decays that are candidates for light dark matter. Additionally, FASER2 will play an important role in the FPF neutrino physics program and will serve as a muon spectrometer for FLArE and FASER2. This document will present different possible designs and technologies for the FASER2 detector and compare their performances for momentum resolution, physics reach and geometrical acceptance to optimise the FASER2 detector both in physics performance and cost efficiency
Search for cascade decays of charged sleptons and sneutrinos in final states with three leptons and missing transverse momentum in collisions at TeV with the ATLAS detector
No full textA search for cascade decays of charged sleptons and sneutrinos using final states characterized by three leptons (electrons or muons) and missing transverse momentum is presented. The analysis is based on a dataset with 140 fb of proton-proton collisions at a center-of-mass energy of TeV recorded by the ATLAS detector at the Large Hadron Collider. This paper focuses on a supersymmetric scenario that is motivated by the muon anomalous magnetic moment observation, dark mattter relic density abundance, and electroweak naturalness. A mass spectrum involving light higgsinos and heavier sleptons with a bino at intermediate mass is targeted. No significant deviation from the Standard Model expectation is observed. This search enables to place stringent constraints on this model, excluding at the 95% confidence level charged slepton and sneutrino masses up to 450 GeV when assuming a lightest neutralino mass of 100 GeV and mass-degenerate selectrons, smuons and sneutrinos.A search for cascade decays of charged sleptons and sneutrinos using final states characterized by three leptons (electrons or muons) and missing transverse momentum is presented. The analysis is based on a dataset with 140 fb-1 of proton-proton (pp) collisions at a center-of-mass energy of s=13 TeV recorded by the ATLAS detector at the Large Hadron Collider. This paper focuses on a supersymmetric scenario that is motivated by the muon anomalous magnetic moment observation, dark-mattter relic density abundance, and electroweak naturalness. A mass spectrum involving light Higgsinos and heavier sleptons with a bino at intermediate mass is targeted. No significant deviation from the Standard Model expectation is observed. This search enables us to place stringent constraints on this model, excluding at the 95% confidence level charged slepton and sneutrino masses up to 450 GeV when assuming a lightest neutralino mass of 100 GeV and mass-degenerate selectrons, smuons and sneutrinos.A search for cascade decays of charged sleptons and sneutrinos using final states characterized by three leptons (electrons or muons) and missing transverse momentum is presented. The analysis is based on a dataset with 140 fb of proton-proton collisions at a center-of-mass energy of =13 TeV recorded by the ATLAS detector at the Large Hadron Collider. This paper focuses on a supersymmetric scenario that is motivated by the muon anomalous magnetic moment observation, dark mattter relic density abundance, and electroweak naturalness. A mass spectrum involving light higgsinos and heavier sleptons with a bino at intermediate mass is targeted. No significant deviation from the Standard Model expectation is observed. This search enables to place stringent constraints on this model, excluding at the 95% confidence level charged slepton and sneutrino masses up to 450 GeV when assuming a lightest neutralino mass of 100 GeV and mass-degenerate selectrons, smuons and sneutrinos
Forecasting constraints on scalar-induced gravitational waves with future pulsar timing array observations
No full textPulsar timing arrays are playing a crucial role in the ongoing gravitational wave astronomy revolution. The current evidence for a stochastic gravitational wave background at nHz frequencies offers an opportunity to discover cosmological signals and threatens the observability of other subdominant gravitational waves (GWs). We explore prospects to constrain second-order scalar-induced GWs (SIGWs) associated with enhanced curvature perturbations in the primordial universe, forecasting realistic future pulsar timing array datasets. We assess how the currently observed signal could eventually limit future capabilities to search for GW relics of primordial phenomena and associated phenomenological consequences such as primordial black hole (PBH) formation. Given the sensitivity of PBH abundance to spectral parameters, measuring it remains a challenge for realistic signals. However, future observation could still rule out nearly subsolar mass PBHs formed through standard formation scenarios in some cases. Future progress in constraining PBH models is expected to stem from theoretical advancements in PBH computations, which should help resolve the tension between different computational methods. The analysis is based on and extends the python code fastpta.Pulsar Timing Arrays are playing a crucial role in the ongoing gravitational wave astronomy revolution. The current evidence for a stochastic gravitational wave background (SGWB) at nHz frequencies offers an opportunity to discover cosmological signals and threatens the observability of other subdominant GWs. We explore prospects to constrain second-order scalar-induced GWs (SIGWs) associated with enhanced curvature perturbations in the primordial universe, forecasting realistic future PTA datasets. We assess how the currently observed signal could eventually limit future capabilities to search for GW relics of primordial phenomena and associated phenomenological consequences such as primordial black hole (PBH) formation. Given the sensitivity of PBH abundance to spectral parameters, measuring it remains a challenge for realistic signals. However, future observation could still rule out nearly subsolar mass PBHs formed through standard formation scenarios in some cases. Future progress in constraining PBH models is expected to stem from theoretical advancements in PBH computations, which should help resolve the tension between different computational methods. The analysis is based on and extends the Python code
CWDM-based radiation-tolerant high-speed optical links
No full textThe consolidation of the Large Hadron Collider (LHC) Beam Instrumentation requires the digitisation of the analogue signals from the detectors within the radiation areas. Subsequently, the digital data are transmitted via the existing fibre plant to the back-end area for processing. In order to manage the increased volume of data with the existing infrastructure, the proposed Coarse Wavelength Division Multiplexing (CWDM) link project merges four optical carrier signals of different wavelengths into a single optical fibre through two high-speed radiation-tolerant optical twin transmitters. This paper outlines the project's current status and radiation tolerance of the constituent components
The High-Granularity Timing Detector for ATLAS at HL-LHC
No full textThe increased particle flux expected at the HL-LHC poses a serious challenge for the ATLAS 1 detector performance, especially in the forward region which has reduced detector granularity. The High-Granularity Timing Detector (HGTD), featuring novel Low-Gain Avalanche Detector silicon technology, will provide pile-up mitigation and luminosity measurement capabilities, and augment the new all-silicon Inner Tracker in the pseudo-rapidity range from 2.4 to 4.0. Two double-sided layers will provide a timing resolution better than 50ps/track for MIPs throughout the HL-LHC running period, and provide a new timing-based handle to assign particles to the correct vertex. The LGAD technology provides suitable gain to reach the required signal-to-noise ratio, and a granularity of 1.3 × 1.3 mm2 (3.6 M channels in total). This paper presents the overall status of the HGTD project with emphasis on the sensor development and module results
