Search Results (253)

The discovery of the Higgs boson in 2012 at the Large Hadron Collider marked a major milestone in our understanding of electroweak symmetry breaking. Since then, increasingly precise measurements by the ATLAS and CMS Collaborations, based primarily on proton–proton collision data at \(\sqrt{s}\) = 13 TeV corresponding to about 140 fb−1 per experiment, have confirmed its compatibility with Standard Model predictions within current uncertainties. The Higgs boson mass is now measured with a precision of about 0.08%, while its couplings to fermions and bosons are determined at the 7–20% level. The completion of the LHC programme and the High-Luminosity LHC, will probe Higgs boson couplings at the fewpercent level. However, sub-percent precision is required for stringent tests of the Standard Model, as any deviation would signal new physics beyond it. This strongly motivates future collider facilities, designed both as high-precision Higgs factories and, in many cases, as energy-frontier machines. Within the framework of the update of the European Strategy for Particle Physics, we discuss the physics case and main characteristics of the proposed particle collider options, highlighting their complementarity, technological challenges, and expected performance. The 2026 Strategy Update identifies the FCC-ee collider as the preferred next flagship project at CERN. Operating at the Z pole and at centre-of-mass energies between 240 and 365 GeV, it would enable model-independent, per-mille-level precision on Higgs boson couplings, while providing a pathway to a future high-energy hadron collider. The Higgs sector thus constitutes a central laboratory for precision tests of the Standard Model and for exploring the fundamental structure of our universe. Full article

The development of modern high-energy astrophysics has been deeply intertwined with advances in particle detector technology. Guido Barbiellini Amidei (1943–2024) played a pivotal role in bridging experimental particle physics and astrophysical observation. His scientific career spanned over four decades, from early electron–positron collider experiments at ADONE and LEP (DELPHI) to space-based missions such as AGILE, Fermi, and PAMELA. This memorial paper reviews the evolution of high-energy astrophysics as a detector-driven science, highlighting key domains where Barbiellini left an indelible mark: gamma-ray astronomy, cosmic-ray physics, and antimatter studies. We discuss his personal contributions to silicon tracking, calorimetry, data analysis, and his leadership in international collaborations. The conceptual impact of his interdisciplinary approach is examined, and future perspectives in the observation of the high-energy universe are outlined, recognizing that the path forward is built on the foundations he helped lay. Full article

The introduction of autonomous mobile robotic systems into ground handling operations at airports has been limited by aviation safety requirements and the high costs associated with a robot colliding with an aircraft. To ensure safety, traditional robotic navigation methods use static buffer zones, which limit the functionality of robotic systems working near the aircraft fuselage. A probabilistic risk assessment model was developed in this study to simulate close-in operation of heterogeneous mobile robotic systems around an aircraft. The proposed model employs a hybrid framework that integrates an extended Kalman filter, Monte Carlo simulations, and a Bayesian network to consider the kinematic uncertainty of a robot, random environmental conditions, and sensor data for real-time evaluation of collision probabilities. The modeling of near-aircraft inspection scenarios conducted in MATLAB demonstrated the feasibility of the proposed approach: the system successfully completed 49 out of 50 simulated missions while testing landing gear inspection scenarios. In addition, the modeling reduced the minimum distance to the inspection object to 0.48 m, compared with a baseline safe distance of 2 m. These results are interpreted as a simulation-based verification of the feasibility of the proposed approach rather than as an operational validation. Experiments, including hardware modeling, data from real sensors, and controlled tests on the airport apron, are required before implementing the approach in real-world conditions. Full article

Resonant transfer and excitation (RTE) is a correlated two-electron ion–atom collision process mediated by the two-center electron–electron interaction: a projectile electron is excited while a target electron is captured, forming doubly excited states. These states decay via X-ray (RTEX) or Auger (RTEA) emission. For sufficiently fast collisions with light targets, RTE becomes analogous to dielectronic capture (DC)—a key plasma process—and is successfully described by the impulse approximation (IA). Early (1983–1992) RTEX and more stringent, state-selective RTEA measurements provided essential indirect DC cross-section information before direct electron–ion measurements became available. A 1992 review by the first author, focusing on zero-degree Auger projectile spectroscopy (ZAPS) of state-selective KLL D states, validated the IA for low-$Z_p$ ($Z_p\le 9$) projectile ions, yet a puzzling systematic discrepancy remained: IA RTEA cross-sections were consistently larger than experimental, with the disagreement increasing as $Z_p$ decreased. The present article reviews RTEA progress since 1992, including new refinements to IA calculations, an exact analytic IA formulation, and instrumental ZAPS improvements. A methodical analysis demonstrates impressive agreement across measurements spanning both pre- and post-1992 eras, including new experimental results, effectively eliminating previous systematic discrepancies. IA validity is confirmed down to boron ions, with He⁺ and certain Li-like ions remaining the only notable exceptions. Recently, a rigorous quantum mechanical ion–atom collision treatment has emerged: nonperturbative close-coupling calculations of transfer excitation for He-like carbon ions colliding with He confirm the dominance of RTE via two-center electron–electron interactions at large impact parameters, yielding RTEA results in excellent agreement with experiments. Full article

This study proposes a novel physical effect arising in radioactive matter: initiation and control of a nuclear chain reaction through high hydrostatic pressure. We present the design of a compression-assisted reactor consisting of a titanium chamber with a cylindrical channel, which can be filled with Deuterium in which Uranium ₉₂U²³⁵ clusters are dissolved. External energy is introduced gradually via a hydraulic piston, which considerably simplifies the reactor mechanics. As hydrostatic pressure increases, the effective interatomic distance decreases due to the overlap of inner electron shells, significantly raising the probability that neutrons released from fissile nuclei will collide with neighboring atoms rather than escape the medium. The safety mechanism is intrinsic to the design: when pressure is reduced, the reactor shuts down autonomously without external intervention. The technical feasibility of the chamber was validated using a weakly compressible inert fluid mixture of kerosene and transformer oil, confirming that the required pressure regime of 200,000 atm is mechanically achievable. The principal anticipated advantage of this effect is the possibility for reduction in the critical mass required to sustain a chain reaction. It corresponds with diminution in the quantity of nuclear fuel needed. Future experiments with radioactive materials could be conducted to develop the proposed phenomenon. Full article

We investigate whether short-range nucleon–nucleon correlations (NN-SRC) and cluster configurations in nuclei can be explored by studying spectator neutrons produced in high-energy nucleus–nucleus collisions. In particular, we propose to measure the multiplicity distributions of forward spectator neutrons in symmetric ¹²C–¹²C and ⁴⁰Ca–⁴⁰Ca collisions at $\sqrt{s_{\mathrm{NN}}}=11$ GeV with the Spin Physics Detector (SPD) at the NICA facility. To assess this method, we simulate the production of spectator nucleons in these reactions using the Abrasion–Ablation Monte Carlo for Colliders model with MST clustering (AAMCC-MST). Short-range nucleon–nucleon correlations inside ¹²C and ⁴⁰Ca are implemented via a Monte Carlo rejection sampling procedure. Our results indicate that spectator production exhibits only a weak dependence on the specific features of NN-SRC. We also observe that including $\alpha$-cluster configurations in ¹²C leads to a reduction of the average multiplicity of spectator neutrons as a function of collision centrality. Full article

This paper describes two front-end architectures developed in a 28 nm CMOS process for the readout of pixel detectors in future high-energy physics (HEP) colliders and advanced X-ray imaging instrumentation. The front-end channels have been developed in the framework of the PiHEX project, funded by the Italian Ministry of University and Research. PiHEX aims to improve the state of the art of pixel readout chip technology in high-luminosity colliders and X-ray imagers in the next generation of free electron lasers (FELs) by developing, in 28 nm CMOS technology, the fundamental microelectronic building blocks for pixel readout chips. Such blocks, also implementing innovative circuit ideas, will enable, in future applications, the integration of large-scale readout chips, meeting a set of challenging requirements, such as high spatial resolution, high signal-to-noise ratio, very wide dynamic range and the capability to withstand unprecedented radiation levels. Two different front-end channels were designed, integrated into two prototype chips, and tested. One architecture, featuring a pixel size of 25 µm × 100 µm, was optimized for tracking applications in high-energy physics experiments, like the ones that take place at CERN in the high-luminosity upgrade of the Large Hadron Collider (LHC), while the second one, featuring a pixel size of 110 µm × 55 µm, was devised for X-ray imaging applications in FELs. Full article

The Large Hadron Collider forward (LHCf) experiment studies the production of neutral particles in the very forward region of high-energy hadronic collisions at the LHC. These measurements provide essential calibration data for hadronic interaction models used in simulations of extensive air showers initiated by ultra-high-energy cosmic rays. The LHCf experiment measures forward-produced neutral particles, such as neutrons, photons, ${\pi }^0$, and $\eta$ mesons, which play a key role in the development of extensive air showers. Proton–proton collisions at the LHC reach center-of-mass energies up to 13.6 TeV, corresponding in the fixed-target frame to cosmic-ray interactions at energies close to 10¹⁷ eV in the Earth’s atmosphere. LHCf has collected data in proton–proton collisions at several energies, as well as in proton–lead collisions, enabling detailed comparisons between experimental results and predictions of hadronic interaction models. This contribution reviews the most significant LHCf results, with emphasis on Run II proton–proton data at $\sqrt{s}=13\mathrm{TeV}$, including measurements of forward neutron, photon, and $\eta$ meson production. Finally, future prospects are discussed, focusing on ongoing analyses of Run III proton–proton data at $\sqrt{s}=13.6\mathrm{TeV}$ and on the final LHCf operation in proton-oxygen collisions at $\sqrt{s_{NN}}=9.6\mathrm{TeV}$, which best reproduces cosmic-ray interactions with nuclei of the Earth’s atmosphere. Full article

Gas-filled discharge capillaries are widely used in the field of plasma-based particle accelerators, due to their compactness, cost-effectiveness and versatility for different applications. Technological improvement of such plasma sources is necessary to enable high energy gain acceleration at the meter scale, as required for next-generation particle colliders and light sources. Beam quality preservation within such an acceleration length involves accurate tuning of the plasma properties. In particular, precise tailoring of the plasma density distribution is required to control the emittance growth of particle bunches during the acceleration process. In this context, this paper presents a scalable and versatile approach for the design of meter-scale discharge capillaries, aimed at achieving fine tuning of the plasma density distribution, with the possibility of locally controlling the density profile by acting on the source geometry. Forty-centimeter-long capillaries are designed using numerical fluid dynamics simulations and tested in a dedicated plasma module. Different arrangements of the gas inlets are tested, with their number and diameter varied, to assess the effect of the capillary geometry on the plasma properties. Plasma density measurements show that a higher number of inlets with variable diameter along the plasma formation channel provides an enhancement in the homogeneity of the electron plasma density distribution. Longitudinal density plateaus are observed along most of the plasma channel length, with a center-to-end density uniformity of up to 80%. The experimental results highlight the proposed approach’s capability to modulate the longitudinal plasma density distribution by acting on the capillary geometry, thus providing uniform density profiles over the meter scale, as required for plasma-based acceleration experiments. Full article

Satellites supporting IoT connectivity may need to serve a large population of LoRa terminals, where collisions among packets using the same spreading factor (SF) can severely degrade uplink reliability. The ALOHA-based access used in LEO-IoT leads to frequent collisions under massive terminal access, which limits system capacity. Conventional signal separation methods that rely on the capture effect typically require a sufficiently large power difference between colliding signals. However, due to the channel characteristics of LEO links, this condition is often difficult to satisfy. We propose ConvLoRa, a collision demodulation method for co-SF LoRa uplink signals in LEO-IoT based on a fully convolutional neural network (FCN). To improve robustness to synchronization deviations, ConvLoRa uses an up-chirp in the preamble as a reference for feature matching, and employs data augmentation to emulate synchronization deviations during training. In addition, a multi-task design is adopted to estimate the payload length with minimal introduction of extra network parameters. Experiments show that ConvLoRa achieves lower demodulation bit error rate (BER) under collision conditions compared with baselines, including CoRa and SIC-based receivers. Under the condition of a two-signal collision with SNR = −9 dB and SF = 8, the BER of the proposed method is 21% that of CoRa and 28% that of the SIC-based method. Full article

With the conclusion of proton–proton collision data-taking in 2025, the ATLAS experiment has now integrated a luminosity exceeding 300 ${\mathrm{fb}}^{-1}$ during the Run 3 period, which began in July 2022 following Long Shutdown 2 (LS2). During LS2, a series of detector upgrades were implemented, including the installation of the New Small Wheel (NSW) in the innermost stations of the Muon Spectrometer end-caps. The ATLAS Muon Spectrometer, the largest muon system ever built at a collider, now comprises both established gaseous detectors—Monitored Drift Tubes, Thin Gap Chambers, and Resistive Plate Chambers—and newer detectors like Micromegas and small-strip TGCs in the NSW. These new systems are now in stable operation following an extensive phase of construction and commissioning, providing enhanced muon tracking and trigger capabilities. This presentation covers the performance of the muon system, focusing on the stability of the established detectors over time, their ability to handle increasing luminosity and associated irradiation levels, and studies on detector aging. Emphasis will be placed on the NSW upgrade, including the strategies adopted for alignment, track reconstruction, and trigger. The performance results presented in this contribution are based on Run 3 data collected up to 2024. Full article

Experimental results are reported to explore the role of release location and release volume on the dispersion of a dense gas cloud around an isolated cubic building. The experiments are analogous to the Thorney Island dense gas dispersion field tests, and the results are qualitatively similar to those of the full-scale tests. Water bath experiments were used in this study with fresh water in a flume representing the atmospheric wind and dyed saltwater representing the dense gas. Results are presented for different relative density flows, quantified using the Richardson number (Ri), for five different release volumes ranging from 10% to 60% of the building volume. Results are also presented for different upstream release distances ranging from 50% to 150% of the building height. Measurements show that there is a complex interaction between release volume, release distance, and Richardson number, and the resulting flow over and around the building. For releases close to the building, the cloud has little distance over which to adjust before being swept around the building and into the building wake. However, for larger release distances, there is adequate distance for the cloud to adjust, with the nature of the adjustment being a function of the Richardson number. For small Ri (low density difference), the cloud spreads out as it moves downstream, mixes with the ambient fluid, and increases in volume such that the volume of the cloud interacting with the building is larger than the initial release. For higher Ri flows (larger density difference), the dense cloud collapses down onto the channel bed, where it spreads out radially as it is advected downstream. The clouds are, therefore, much shallower than the building height when they collide with the building. This competition between the collapse of the cloud and its advection downstream is parameterized using a novel ‘adjusted Richardson number’ $R{i}^{*}$. Full article

Brazilian women’s migration to Portugal has increased in recent years, driven by hopes of safety, improved living conditions, and professional opportunities. Yet these aspirations frequently collide with structural barriers and experiences of discrimination that generate profound psychological distress. Drawing on intersectional feminist epistemology and social constructionism, this qualitative study examines how social markers of difference—gender, class, race, and nationality—intersect to shape the psychological well-being of Brazilian immigrant women in Portugal. Semi-structured interviews were conducted with fifteen women who sought psychological support after migration. Reflexive thematic analysis revealed three interrelated themes: the migration journey, exposing the gap between idealised expectations and the realities of bureaucracy, precarity, and exclusion; inhabiting a new territory, marked by social isolation, racism, xenophobia, and professional devaluation; and the mental-health impacts of migration, showing how structural vulnerabilities and institutional racism underpin depression, anxiety, and, in some cases, suicidal ideation. The findings challenge the individualisation of suffering, showing that psychological distress stems not from personal fragility but from systems of exclusion and enduring colonial legacies. This study underscores the need for culturally responsive and rights-based mental health care and public policies that recognise migration as a human experience demanding dignity, ethical commitment, and social justice. Full article

Soil salinization has become a major threat affecting global arable productivity. Rice cultivation with amendment application is considered an important approach for saline–sodic soil reclamation. Saline–sodic soil without vegetation was selected as the study subject to investigate the effects of amendments in rice cultivation on salinity and sodicity through a pot experiment. The results revealed that the application of desulfurization gypsum combined with aluminum sulfate to saline–sodic soil significantly contributed to decreases in soil salinity and sodicity. The soil pH in the 0–10 cm, 10–20 cm and 20–30 cm soil layers decreased from 9.41–9.84 to 8.06–9.24, whereas the exchangeable sodium percentage (ESP) decreased from 28.98–33.24% to 19.76–30.82%, respectively. The increase in soil exchangeable Ca²⁺ was accompanied by a decrease in soil exchangeable Na⁺. Additionally, the application of desulfurization gypsum combined with aluminum sulfate to saline–sodic soil resulted in significant decreases in total alkalinity (TA) and the sodium adsorption ratio (SAR) and an increase in soluble Ca²⁺. The analysis indicated that soluble Ca²⁺ derived from desulfurization gypsum is the predominant factor affecting the variation in the soil pH, ESP, SAR, and exchangeable Na⁺ and Ca²⁺. The reductions in salinity and sodicity are attributed to the replacement of Ca²⁺ derived from desulfurization gypsum with Na⁺ on soil collides. Simultaneously, H⁺ formed by the hydrolysis of aluminum sulfate neutralizes HCO₃⁻ and CO₃²⁻ in the water layer. Full article

In phenomenological studies of multiparticle production, transverse-momentum spectra measured in experiments frequently display an approximately power-law falloff, for which the Tsallis-type functional form is commonly employed as an effective parametrization. Within this framework, the emergence of such spectra is interpreted as a manifestation of nonextensive statistical behavior. An analogous power-law structure, however, can be reproduced without explicitly postulating Tsallis statistics by assuming the presence of intrinsic fluctuations of the local temperature (T) in the hadronizing medium; in that case, the observed deviations from a purely exponential spectrum are encapsulated by the nonextensivity index (q). We show that temperature fluctuation mechanisms capable of generating Tsallis-like power-law distributions in multiparticle production necessarily induce nontrivial inter-particle correlations among the emitted hadrons. Building on this observation, we outline a strategy to discriminate fluctuations realized on an event-by-event basis from those arising predominantly through event-to-event variability. Such a separation may be particularly pertinent for the characterization of high-multiplicity (high-density) final states produced at the Large Hadron Collider. Full article