Observation of non-homogeneous scenarios for different temperatures in hadron(nucleus)-nucleus collisions at RHIC and LHC energies
2022, Chinese Journal of Physics
We used the modified Hagedorn function and analyzed the experimental data measured by the BRAHMS, STAR, PHENIX, and ALICE Collaborations in Copper–Copper, Gold–Gold, deuteron–Gold, Lead–Lead, proton–Lead and proton–proton collisions, and extracted the related parameters (kinetic freezeout temperature, transverse flow velocity, kinetic freezeout volume, mean transverse momentum, and initial temperature) from the transverse momentum spectra of the particles (non-strange and strange particles). We observed that all the above parameters increase from peripheral to central collisions, except transverse flow velocity, which remains unchanged. The kinetic freezeout temperature depends on the particle’s interaction cross-section such that a larger cross-section corresponds to a smaller and reveals the two kinetic freezeout scenarios. Similarly, the initial temperature follows the mass dependency of the particle, and it increases with the particle mass. The transverse flow velocity and mean transverse momentum depend on the particle’s specie. The former decreases while the latter increases for the massive particles. Furthermore, different freezeout surfaces for different particles are observed as the kinetic freezeout volume decreases for the heavier particles. We also extracted the entropy index-parameter “” and the parameter , the former remains almost unchanged while the latter decreases from central collisions to the periphery. Furthermore, the kinetic freezeout temperature, transverse flow velocity, kinetic freezeout volume, initial temperature, mean transverse momentum and the parameter at LHC are larger than that of RHIC, showing their dependence on the collision cross-section and collision energy.
Decoupling of non-strange, strange and multi-strange particles from the system in Cu–Cu, Au–Au and Pb–Pb collisions at high energies
2022, Chinese Journal of Physics
Transverse momentum spectra of the non-strange, strange and multi-strange particles in central and peripheral Copper–Copper, Gold–Gold and Lead–Lead collisions are analyzed by the blast wave model with Boltzmann Gibbs statistics. The model results are approximately in agreement with the experimental data measured by BRAHMS, STAR, SPS, NA 49 and WA 97 Collaborations in special transverse momentum ranges. Bulk properties in terms of kinetic freeze-out temperature, transverse flow velocity and freeze-out volume are extracted from the transverse momentum spectra of the particles. Separate freeze-out temperature is observed for the non-strange, strange and multi-strange particles which may be due to different reaction cross-section of the interacting particles and it reveals the triple kinetic freeze-out scenario in collisions at BRAHMS, STAR, SPS, NA 49 and WA 97 Collaborations. However the transverse flow velocity and kinetic freeze-out volume are mass-dependent, and both of them decrease for the massive particles. Furthermore, the kinetic freeze-out temperature, transverse flow velocity and kinetic freeze-out volume in central nucleus–nucleus collisions are larger than those in peripheral collisions. Besides, the larger kinetic freeze-out temperature and kinetic freeze-out volume are observed in the heaviest nuclei collisions, indicating their dependence on the size of interacting system.
Comparing a few distributions of transverse momenta in high energy collisions
2019, Results in Physics
Transverse momentum spectra of particles produced in high energy collisions are very important due to their relations to the excitation degree of interacting system. To describe the transverse momentum spectra, one can use more than one probability density functions of transverse momenta, which are simply called the functions or distributions of transverse momenta in some cases. In this paper, a few distributions of transverse momenta in high energy collisions are compared with each other in terms of plots to show some quantitative differences. Meanwhile, in the framework of Tsallis statistics, the distributions of momentum components, transverse momenta, rapidities, and pasudorapidities are obtained according to the analytical and Monte Carlo methods. These analyses are useful to understand carefully different distributions in high energy collisions.
Particle species and energy dependencies of freeze-out parameters in high-energy proton-proton collisions
2022, arXiv
Particle species and energy dependencies of freeze-out parameters in high-energy proton–proton collisions
2022, European Physical Journal Plus
Centrality dependence of kinetic freeze-out temperature and transverse flow velocity in high energy nuclear collisions
2022, Indian Journal of Physics
Research article
Effect of guide vane height on the performance and emissions of a compression ignition (CI) engine run with biodiesel through simulation and experiment
Applied Energy, Volume 136, 2014, pp. 431-444
This research investigated the effect of guide vanes installed in front of the intake runner of a compression ignition (CI) engine run with biodiesel. Firstly, the simulation method used SolidWorks and ANSYS-CFX to determine the optimum vane height of the guide vane from among 10 variation models with different vane heights between 0.10 and 1.00 times the radius of the intake runner (R) (called 0.10R for 0.10 times R, etc.). The simulation results of in-cylinder turbulence kinetic energy (TKE), velocity, vorticity and swirling strength were presented and discussed. Based on these results, 0.70R was found to be the optimum guide vane height as it improved TKE, mostly improved velocity and partly improved vorticity, swirling strength within the fuel injection region from crank angles before the start of injection up to the first part of expansion stroke. Five guide vane models (0.10R, 0.30R, 0.50R, 0.70R, and 0.90R) were then fabricated and tested on a CI generator diesel engine run with biodiesel coupled with a load bank. Based on the experimental results, 0.70R guide vane model showed the most improvements as it reduced the brake-specific fuel consumption (BSFC), carbon monoxide (CO) and hydrocarbons (HC) as well as increased engine efficiency compared to the run without the guide vanes when ran with biodiesel. Hence, this research found that using guide vanes can improve the performance and reduce the emissions of CI engine run with biodiesel.
Research article
Pseudo-critical enhancement of thermal photons in relativistic heavy-ion collisions?
Nuclear Physics A, Volume 933, 2015, pp. 256-271
We compute the spectra and elliptic flow of thermal photons emitted in ultrarelativistic heavy-ion collisions (URHICs) at RHIC and LHC. The thermal emission rates are taken from complete leading-order rates for the QGP and hadronic many-body calculations including baryons and antibaryons, as well as meson-exchange reactions (including Bremsstrahlung). We first update previous thermal fireball calculations by implementing a lattice-QCD based equation of state and extend them to compare to recent LHC data. We then scrutinize the space–time evolution of Au–Au collisions at RHIC by employing an ideal hydrodynamic model constrained by bulk- and multistrange-hadron spectra and elliptic flow, including a non-vanishing initial flow. We systematically compare the evolutions of temperature, radial flow, azimuthal anisotropy and four-volume, and exhibit the temperature profile of thermal photon radiation. Based on these insights, we put forward a scenario with a “pseudo-critical enhancement” of thermal emission rates, and investigate its impact on RHIC and LHC direct photon data.
Research article
Compact 5-LEDs illumination system for multi-spectral surface plasmon resonance sensing
Sensors and Actuators B: Chemical, Volume 209, 2015, pp. 208-211
In this contribution, we quantify the performances of a low-cost, compact, multi-spectral illumination system allowing spectral interrogation to be performed in surface plasmon resonance imaging (SPRI) systems. Previous work demonstrated the feasibility of spectral interrogation based on a discrete number of scanning wavelengths using a white source and monochromator. Here, we expand this concept by building a multi-spectral SPRI system with five light-emitting diodes (LEDs). The development focuses on the improvement of the illumination stability, which is a critical parameter for the precision of the spectral interrogation measurement. The obtained prototype exhibits sensitivity and resolution properties comparable with reflectivity-interrogation-based SPRI systems, with the advantages of spectral interrogation, i.e. increased dynamical range and robustness towards solution index variations. These performances, as well as the real-time and 2-dimensional imaging modalities of the five-LEDs setup, are illustrated by a standard experiment of DNA–DNA interaction monitoring on a biochip format.
Research article
Improvement in patient-reported outcomes after rituximab in rheumatoid arthritis patients: An open-label assessment of 175patients
Joint Bone Spine, Volume 82, Issue 6, 2015, pp. 451-454
Patient-reported outcomes (PROs) reflect treatment efficacy from the patients’ perspective. The objective was to assess PROs improvement with rituximab in rheumatoid arthritis.
Patients with long-standing rheumatoid arthritis received rituximab 1000mg twice at 2weeks interval, and were assessed over 6months. PROs including physical PROs (pain, functional assessment, physical quality of life) and mental or mixed aspects (fatigue, sleep and mental quality of life) were assessed. Standardized response means were calculated. Early improvement in PROs was used to predict EULAR response at 6months.
For the 175patients (mean age 54.6±10.6years, mean disease duration 12.9±9.3years), the plateau of efficacy of rituximab on PROs was reached at week12, and the effect was more prominent on physical PROs (e.g., pain standardized response means −0.75 [95% confidence interval −0.91; −0.60]), than on sleep (−0.43; [−0.56; −0.29]). It was not possible to accurately predict 6-month EULAR response by early improvement in PROs.
Rituximab was effective on PROs with an early effect. PROs reflecting physical aspects were more modulated by this biologic than other PROs (fatigue, sleep or mental quality of life). Links between sleep difficulties, fatigue and RA should be further studied.
Research article
Origin of the large Pliocene and Pleistocene debris flows on the Algarve margin
Marine Geology, Volume 377, 2016, pp. 58-76
The base of the Faro contouritic drift (IODP Site U1386) on the northern margin of the Gulf of Cádiz (Algarve margin) is characterized by two sequences of frequent gravity deposits with different ages and compositions. Among these gravity deposits, several relatively thick debrites (up to 12m) have been observed and studied in detail.
Sedimentological analyses have been performed and because of non-turbulent behavior of debris flows, detailed micropaleontological studies could be realized. Planktonic foraminifera thus allowed establishing a detailed biostratigraphy of these deposits. Benthic foraminifer and ostracod assemblages were used to evaluate the origin of the sediment composing these debris flows and estimate their run-out distance.
These debrites are dated from Early Pliocene and early Pleistocene, and were deposited in a mesobathyal environment. They comprise silty mud clasts and matrixes with sand content up to 34%. The Early Pliocene debrites are bioclast-rich whereas the Early Pleistocene debrite is enriched in terrigenous particles. The data indicates that these debrites were triggered on the continental shelf and traveled less than 100km, eroding the seafloor all along their path for the Early Pliocene debrites and only the first part of their path for the early Pleistocene debrite. Matrixes originate from failure areas whereas eroded sediments along the flow pathway are incorporated into the flow as clasts.
High abundance of shelf fauna during the Early Pliocene and great supply of terrigenous particles from rivers during the early Pleistocene in the south-western Iberian margin have favored gravity flows from the continental shelf to the slope. The contouritic paleo-moat of the Faro drift has been a determining channeling feature for gravity flows along the Algarve margin during the early Pleistocene, testifying of the strong interaction between MOW circulation and down-slope processes. Tectonic and diapiric activities were significant during Early Pliocene and early Pleistocene on the Algarve margin and could have been triggering parameters of failures related to these debris flows.
Research article
Constraints on the noble gas composition of the deep mantle by bubble-by-bubble analysis of a volcanic glass sample from Iceland
Chemical Geology, Volume 417, 2015, pp. 173-183
Contamination of samples by air-derived noble gases is a well-known problem in noble gas geochemistry, and, as a result, determining the true neon and argon isotopic ratios of the mantle is not straightforward. Here, we directly target individual bubbles in an Icelandic volcanic glass, DICE 11, with a 193nm excimer laser in order to reduce air-contamination, and analyze He and Ar isotopes, plus 22Ne abundances, on a Helix SFT mass-spectrometer. The CO2 content of the bubbles was measured with a capacitance manometer. In addition, new He, Ne and Ar compositions obtained by crushing on similar samples (DICE 10 and DICE 11) are presented.
Our analyses show that 3He/4He ratios are homogeneous in all the vesicles in this glass sample at 17.4±0.4 Ra and are consistent with analyses by crushing. Precise 40Ar/36Ar isotopic ratios were obtained on the largest vesicles only, due to high blank contributions to the smallest vesicles, and are 8600±700, i.e. the highest values measured so far in primitive basalts from Iceland. Considering that the Ar and He isotopic compositions obtained for individual vesicles (by laser ablation) are representative of the true mantle source values, not contaminated by air, we can precisely correct the Ne isotopic analyses obtained by crushing for air contamination; the corrected 20Ne/22Ne ratios are consistent with the presence of neon-B in the sub-Icelandic mantle, which is consistent with the hypothesis that neon in the OIB source region has an irradiated meteorite origin rather than purely solar. In contrast to He and Ar isotopic compositions (which are homogeneous), the relative He–Ne–Ar–CO2 abundances in the different bubbles are heterogeneous and show strong correlations which are compatible with equilibrium degassing of the magma. Because He and CO2 do not fractionate during this degassing, we can precisely constrain the CO2/3He ratio of the mantle source at 6.7±0.5∗108, at the lower end of the MORB range. Therefore the deep mantle below Iceland is not enriched in carbon compared to the upper mantle (via recycling, for example).
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