Heavy Experiments Research Articles

ϕ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\phi $$\\end{document} meson mass and decay width in magnetized strange hadronic matter

We investigate the medium modifications in mass and decay width of ϕ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\phi $$\\end{document} meson in the presence of an external magnetic field. The in-medium mass of ϕ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\phi $$\\end{document} meson has been calculated using the decay process ϕ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\phi $$\\end{document}→\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\rightarrow $$\\end{document}KK¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$K {\\bar{K}}$$\\end{document} at one-loop level. The medium modifications are introduced by using a chiral SU(3) model employing a mean-field effective approach. Due to the introduction of the magnetic field, masses of charged K+\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$K^+$$\\end{document} and K-\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$K^-$$\\end{document} increases with advancing magnetic field values. A negligible change in the value of neutral K0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$K^0$$\\end{document} and K¯0\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\bar{K}}^0$$\\end{document} has been observed for varying magnetic fields. Due to electromagnetic interactions with charged K and K¯\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$${\\bar{K}}$$\\end{document} mesons, there is a gradual augmentation in the effective mass of ϕ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\phi $$\\end{document} meson. The probability of the mentioned decay process ceases to be zero for low density and strangeness fraction values at higher magnetic field values. Investigating the decay width and effective mass of ϕ\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\phi $$\\end{document} meson under the influence of an external magnetic field is relevant to understanding the hadronic matter properties under extreme conditions achievable at heavy-ion collision experiments.

Lattice QCD estimates of thermal photon production from the QGP

Thermal photons produced in heavy-ion collision experiments are an important observable for understanding quark-gluon plasma (QGP). The thermal photon rate from the QGP at a given temperature can be calculated from the spectral function of the vector current correlator. Extraction of the spectral function from the lattice correlator is known to be an ill-conditioned problem, as there is no unique solution for a spectral function for a given lattice correlator with statistical errors. The vector current correlator, on the other hand, receives a large ultraviolet contribution from the vacuum, which makes the extraction of the thermal photon rate difficult from this channel. We therefore consider the difference between the transverse and longitudinal part of the spectral function, only capturing the thermal contribution to the current correlator, simplifying the reconstruction significantly. The lattice correlator is calculated for light quarks in quenched QCD at T=470 MeV (∼1.5Tc), as well as in 2+1 flavor QCD at T=220 MeV (∼1.2Tpc) with mπ=320 MeV. In order to quantify the nonperturbative effects, the lattice correlator is compared with the corresponding NLO+LPMLO estimate of correlator. The reconstruction of the spectral function is performed in several different frameworks, ranging from physics-informed models of the spectral function to more general models in the Backus-Gilbert method and Gaussian process regression. We find that the resulting photon rates agree within errors. Published by the American Physical Society 2024

Effectiveness of denoising diffusion probabilistic models for fast and high-fidelity whole-event simulation in high-energy heavy-ion experiments

Effectiveness of denoising diffusion probabilistic models for fast and high-fidelity whole-event simulation in high-energy heavy-ion experiments

The QCD phase diagram and Beam Energy Scan physics: A theory overview

We review recent theoretical developments relevant to heavy-ion experiments carried out within the Beam Energy Scan program at the Relativistic Heavy Ion Collider. Our main focus is on the description of the dynamics of systems created in heavy-ion collisions and establishing the necessary connection between the experimental observables and the QCD phase diagram.

Gate breakdown induced stuck bits in sub-20 nm FinFET SRAM

This paper discusses the stuck bits induced by the gate breakdown of PMOS in the sub-20 nm FinFET static random access memory (SRAM) device. After the heavy-ion experiment, several stuck bits are in the FinFET SRAM matrix, which cannot be set or reset. To investigate the factors that caused the stuck bit, we perform the electrical failure analysis (EFA) to measure the electric characteristics of the transistors in the stuck bits and normal cells separately. The measurement results show a clear gate breakdown at the PMOS pull-up (PPU) transistor in all of the measured SRAM cells. Meanwhile, the SPICE simulation based on the EFA results verifies the impact of the damaged PPU. Finally, considering all of the phenomena, the charge deposition from single events is the major mechanism that causes the stuck bits in FinFET SRAM. The experiment results alert a potential gate breakdown risk in the ultra-high-density FinFET SRAM applied in the space environment.

Theoretical Perspectives on Viscous Nature of Strongly Interacting Systems

Matter prevailing during the early stages of the Universe or under extreme conditions in high-energy heavy-ion experiments supposedly possesses a rich phase structure. During the evolution of such a system, the complicated pictures of transitions among various phases are studied as part of hydrodynamics. This system, on most occasions, is considered to be non-viscous. However, various theoretical studies reveal the importance of incorporating viscous effects into the analysis. Here, the paper discusses the behavioral patterns of transport coefficients with varying temperatures and chemical potentials to obtain a qualitative, if not quantitative, picture of the same. Discussions are also shared regarding their impacts on such an exotic system for different energies, as explored in the experimental domain. This theoretical analysis, made using the structure of the Polyakov–Nambu–Jona-Lasinio (PNJL) model with a 2+1-flavor quark–antiquark system reveals important aspects of the inclusion of viscous effects in the hydrodynamic studies of QGP.

ALICE upgrades during the LHC Long Shutdown 2

A Large Ion Collider Experiment (ALICE) has been conceived and constructed as a heavy-ion experiment at the LHC. During LHC Runs 1 and 2, it has produced a wide range of physics results using all collision systems available at the LHC. In order to best exploit new physics opportunities opening up with the upgraded LHC and new detector technologies, the experiment has undergone a major upgrade during the LHC Long Shutdown 2 (2019–2022). This comprises the move to continuous readout, the complete overhaul of core detectors, as well as a new online event processing farm with a redesigned online-offline software framework. These improvements will allow to record Pb-Pb collisions at rates up to 50 kHz, while ensuring sensitivity for signals without a triggerable signature.

Chiral magnetic waves in strongly coupled Weyl semimetals

Propagating chiral magnetic waves (CMW) are expected to exist in chiral plasmas due to the interplay between the chiral magnetic and chiral separation effects induced by the presence of a chiral anomaly. Unfortunately, it was pointed out that, because of the effects of electric conductivity and dissipation, CMW are overdamped and therefore their signatures are unlikely to be seen in heavy-ion collision experiments and in the quark gluon plasma. Nonetheless, the chiral anomaly plays a fundamental role in Weyl semimetals and their anomalous transport properties as well. Hence, CMW could be potentially observed in topological semimetals using table-top experiments. By using a holographic model for strongly coupled Weyl semimetals, we investigate in detail the nature of CMW in presence of Coulomb interactions and axial charge relaxation and estimate whether, and in which regimes, CMW could be observed as underdamped collective excitations in topological materials.

Death Wishes, Aging Patients, and Euthanasia

The authors are searchers in psychopathology and communicate here about the dead wishes in relation to euthanasia. In Europe, the question comes regularly up to know if the law should be changed concerning the prohibition of euthanasia. The health system obeys progressively a modern idea of comfort and the “good life”. The authors are psychotherapists and their methodology is based mainly on phenomenological psychology, psychoanalysis, and psychopathology. Statistics of the French Ministry of Health will support their statements. Different clinical experiences with young patients, aging patients, or near-to-death patients are crossed and compared to those marked by heavy experiences like rape or amputation. The unbearable nature of their suffering makes them ask frequently to stop the pain. They would prefer being dead. This contribution examinates this kind of demand to find a helpful position for the caregiver and the patient. We should consider that near-death patients may often be at the climax of anxiety and depression is likely to switch over to dementia. In asking to finish with life, this purpose may change one day to another – sometimes it just highlights the wish to see things changed. The position of society and the medical staff has a high influence as well. Asking for euthanasia shows the variety of the same words that have different meanings from a medical, psychological, or psychopathological viewpoint. The purpose is to consider these aspects with the patient’s demand.

Quark Clusters, QCD Vacuum and the Cosmological 7Li, Dark Matter and Dark Energy Problems

We propose a non-exotic electromagnetic solution (within the standard model of particle physics) to the cosmological 7Li problem based upon a narrow 2 MeV photo-emission line from the decay of light glueballs (LGBs). These LGBs form within color superconducting quark clusters (SQCs), which are tens of Fermi in size, in the radiation-dominated post-BBN epoch. The mono-chromatic line from the LGB→γ+γ decay reduces Big Bang nucleosynthesis (BBN) 7Be by 2/3 without affecting other abundances or the cosmic microwave background (CMB) physics, provided the combined mass of the SQCs is greater than the total baryonic mass in the universe. Following the LGB emission, the in-SQC Quantum ChromoDynamics (QCD) vacuum becomes unstable and “leaks” (via quantum tunneling) into the external space-time (trivial) vacuum, inducing a decoupling of SQCs from hadrons. In seeking a solution to the 7Li problem, we uncovered a solution that also addresses the Dark Energy (DE) and dark matter (DM) problem, making these critical problems intertwined in our model. Being colorless, charge-neutral, optically thin, and transparent to hadrons, SQCs interact only gravitationally, making them a viable cold DM (CDM) candidate. The leakage (i.e., quantum tunneling) of the in-SQC QCD vacuum to the trivial vacuum offers an explanation of DE in our model and allows for a cosmology that evolves into a ΛCDM universe at a low redshift with a possible resolution of the Hubble tension. Our model distinguishes itself by proposing that the QCD vacuum within SQCs possesses the ability to tunnel into the exterior trivial vacuum, resulting in the generation of DE. This implies the possibility that DM and hadrons might represent distinct phases of quark matter within the framework of QCD, characterized by different vacuum properties. We discuss SQC formation in heavy-ion collision experiments at moderate temperatures and the possibility of detection of MeV photons from the LGB→γ+γ decay.

The development of segmented electrode thin-film parallel plate avalanche counter (PPAC)

In order to improve the counting rate and position resolution of the Parallel Plate Avalanche Counter (PPAC) within the Compact Spectrometer for Heavy Ion Experiment, a new strip film-structured PPAC has been developed. The developped PPAC detector consists of three layers of film electrodes. The upper and lower layers which serve as the anodes are comprised of self-developed strip film electrodes, oriented perpendicularly to each other. The middle layer utilizes double-sided aluminized Mylar film as the cathode. There is a 3 mm gap between each layer, and the detector has an effective area of 76 mm× 76 mm. Operating in a low-pressure environment with isobutane gas as the working medium, the performance of the PPAC has been measured using a 5.486 MeV α radiation source. The measurement results indicate that the overall position resolution of the PPAC attains approximately 380 μm, and the position resolution improves to 300 μm when using slit width correction. Finally, the Monte Carlo simulation has been performed to simulate the distribution of electrons generated by the detector's ionization under the same conditions on the anode readout strip. The simulation results closely matches the observed multiplicity of hit anode readout strips in measurement.

Finite volume effects near the chiral crossover

The effect of a finite volume presents itself both in heavy ion experiments as well as in recent model calculations. The magnitude is sensitive to the proximity of a nearby critical point. We calculate the finite volume effects at finite temperature in continuum QCD using lattice simulations. We focus on the vicinity of the chiral crossover. We investigate the impact of finite volumes at zero and small chemical potentials on the QCD transition though the chiral observables.

What ultracold atoms tell us about the real-time dynamics of QCD in extreme conditions

I review developments of how compact table-top setups with ultracold atoms can help us to understand the more complex real-time dynamics of QCD probed in heavy-ion collision experiments.

QCD material parameters at zero and non-zero chemical potential from the lattice

Using an eighth-order Taylor expansion in baryon chemical potential, we recently obtained the (2+1)-flavor QCD equation of state (EoS) at nonzero conserved charge chemical potentials from the lattice. We focused on strangeness-neutral, isospin-symmetric QCD matter, which closely resembles the situation encountered in heavy-ion collision experiments. Using this EoS, we present here results on various QCD material parameters; in particular we compute the specific heat, speed of sound, and compressibility along appropriate lines of constant physics. We show that in the entire range relevant for the beam energy scan at RHIC, the specific heat, speed of sound, and compressibility show no indication for an approach to critical behavior that one would expect close to a possibly existing critical endpoint.

Optical Response of Various Heavy Metal Ions-Based Carbon Dots Photoluminescent Quenching Effect

Carbon nanodots (Cdots) are a type of semiconductor carbon-based nanomaterial that is gaining popularity due to its excellent characteristics (e.g., biocompatibility, unique optical properties, low cost, eco-friendly, and high stability). In terms of physicochemical properties for an environmentally friendly sensor application, this material also has an excellent ability to detect heavy metal ions in the biosphere. In this study, we proposed a comprehensive optical characterization to examine the sensitivity of the Cdots probe for three heavy metal ions (i.e., Mn, Pb, and Cr ions) and compare the performance. The results of the experiment revealed that each heavy metal ion reacted differently to the physical properties of Cdots. With the addition of Cr, Mn, and Pb metal ions from the original Cdot solution, which is only 1.45 ns, the lifetime of quenched Cdots is 2.55 ns, 3.15 ns, and 2.15 ns, respectively, according to the TRPL experiments. With additional Cr, Mn, and Pb discovered, the intensity of PL dropped by 5.7%, 14.2%, and 21.4%, respectively. Among these various heavy metal ions, Pb ions show the most affected by the quenching effect in Cdots-based photoluminescence, FTIR, and ultraviolet-visible light absorption characterization. Based on the results of three heavy metal ion experiments, this study can be implemented as the heavy metal ion sensor-based luminescence quenching effect of Cdots.

Total ionizing dose and single event effect response of 22 nm ultra-thin body and buried oxide fully depleted silicon-on-insulator technology

The test chip including transistors and Static Random Access Memory (SRAM) is proposed and fabricated by an advanced 22 nm Ultra-Thin Body and Buried Oxide Fully Depleted Silicon-on-Insulator (UTBB FD-SOI) technology. Experimental results of Co-60 irradiation and heavy ion experiments are presented. Total Ionizing Dose (TID) experiment results show that the threshold voltage shift of the transistor is about 100 mV when the dose is 500 krad(Si) and the SRAM irradiated to a dose of at least 300 krad(Si) can maintain its functionality, which means that 22 nm UTBB FD-SOI devices exhibit significantly improved total dose tolerance performance compared to the previous generation process. TID-induced threshold voltage shift in conventional-well nMOSFET can be mitigated by applying biasing to back-gate, while back-gate biasing is invalid for TID mitigation of the conventional-well pMOSFET. Heavy ion experimental results make known that 22 nm UTBB FD-SOI technology has contributions to Single Event Effect (SEE) hardness and the hardened SRAM has higher single event upset (SEU) tolerance and even SEU immunity. The research indicates that the circuits manufactured by 22 nm UTBB FD-SOI technology have great potential space applications in harsh radiation environments.

Semi-empirical parameterization of HI/p L-shell X-ray production cross section ratios in Bi for Heavy Ion PIXE

Quantitative analysis of materials from Heavy Ion PIXE spectra remains impeded by the lack of reliable X-ray production cross section (XPCS) data. Although efforts at experimental Heavy Ion induced XPCS measurements still continue, Multiple Ionisation (MI) effects, which are not fully described by theory, render simulations of heavy ion PIXE data unreliable for large Z1/Z2 collisions, especially at low energies. This is also exacerbated by the random selection of projectile-target combinations for measured and reported experimental data available to validate theory. This study explored heavy ion induced X-ray production cross section deviations from those induced by protons at the same ion velocity. This enabled evaluations of the degree to which cross sections are enhanced through MI effects, with the aim of predicting XPCS due to heavy ion impact. The evaluation was carried out through the scaling of experimental heavy ion to theoretical proton cross section ratios (R), which were then used for the interpolation of XPCS in the same target element for ‘missing’ projectiles within the range of evaluation. Here we present measurements of heavy ion induced total L-shell XPCS in Bi, carried out to determine HI/p MI induced deviations due to C, F, Cl and Ti projectiles at an ion velocity range of (0.2–1.0) MeV/nucleon.

An aerogel RICH detector for the next generation heavy-ion experiment at LHC

The ALICE collaboration is proposing a new apparatus, ALICE 3, to investigate the Quark Gluon Plasma (QGP) properties. In this context, conceptual studies for the development of a RICH detector for ALICE 3 are ongoing. The proposed baseline layout is a proximity-focusing RICH, using aerogel (refractive index n= 1.03 at λph= 400 nm) as Cherenkov radiator and a layer of Silicon Photomultipliers (SiPM) for the photon detection. A multi-layer (focusing) aerogel layout, with increasing refractive index, is also considered. If good time resolution of ≈ 20 ps can be achieved in the SiPM photons detectors, they can be able to identify charged hadrons via TOF measurements. The detector specifications and performance, obtained by means of dedicated Monte Carlo simulation, are presented. The R&D challenges related to the proposed design are also discussed.

Functional characterization of modules for the Silicon Tracking System of the CBM experiment

The CBM experiment is a fixed-target heavy-ion physics experiment at the future FAIR facility, designed to explore the QCD phase diagram at high baryon-net densities and moderate temperatures. To address its complex physics program, the experiment is conceived to operate at beam–target interaction rates up to 10 MHz with self-triggered front-end electronics and free-streaming readout architecture. The Silicon Tracking System (STS) of CBM is the main charged-particle tracker, capable of delivering time-stamped hits for online tracking and event building, and momentum measurement inside a superconducting dipole magnet. The functional unit of the STS is the detector module, a device assembled from a double-sided silicon microstrip sensor connected via a stack of microcables to a pair of front-end boards carrying the readout electronics. The assembly and successful operation of STS modules, produced with close-to-final components, was an important milestone achieved in recent years. The systematic study of the modules’ performance is also necessary for optimizing the assembly procedure and ensuring high production yield. This work reports a series of tests, which aim to evaluate the module’s operation and establish the basic criteria for quality control. It summarizes the procedures and results of different measurements performed with the modules, starting with noise estimation and charge amplitude calibration, resulting in the linearization of the channel’s ADC and a homogeneous threshold distribution. Those results were verified using a radioactive source. Additionally, first conclusions concerning the assembly yield in terms of number of functional channels were obtained. These studies represent a fundamental step towards the series production readiness for the final STS detector.

A Neural-Network-Based Competition between Short-Lived Particle Candidates in the CBM Experiment at FAIR

Fast and efficient algorithms optimized for high performance computers are crucial for the real-time analysis of data in heavy-ion physics experiments. Furthermore, the application of neural networks and other machine learning techniques has become more popular in physics experiments over the last years. For that reason, a fast neural network package called ANN4FLES is developed in C++, which will be optimized to be used on a high performance computer farm for the future Compressed Baryonic Matter (CBM) experiment at the Facility for Antiproton and Ion Research (FAIR, Darmstadt, Germany). This paper describes the first application of ANN4FLES used in the reconstruction chain of the CBM experiment to replace the existing particle competition between Ks-mesons and Λ-hyperons in the KF Particle Finder by a neural network based approach. The raw classification performance of the neural network reaches over 98% on the testing set. Furthermore, it is shown that the background noise was reduced by the neural network-based competition and therefore improved the quality of the physics analysis.