122 research outputs found
Particle production in 158.A GeV Pb + Pb collisions
No full textThe production of neutral pions in 158.A GeV /sup 208/Pb+/sup 208/Pb collisions has been studied in the WA98 experiment. The centrality dependence of the neutral pion production is investigated. An invariance of the spectral shape and a simple scaling of the yield with the number of participating nucleons is observed for centralities with more than about 50 participants. The transverse mass spectrum is analyzed in terms of a thermal model with hydrodynamic expansion. The high accuracy and large kinematic coverage of the measurement constrains the extracted freeze-out parameters, and provides information on the freeze-out velocity profile. (18 refs)
Sistema de monitoreo multivariable para electrolizadores alcalinos de baja escala
No full textEn este estudio se enfatiza la relevancia de la transición hacia energías renovables mediante la implementación de electrolizadores alcalinos (AWEs) para la producción de hidrógeno verde. Los AWEs, desde su introducción en el siglo XVIII, han evolucionado desde capacidades iniciales de 0.08 Nm³/h hasta alcanzar 1.200 Nm³/h en configuraciones industriales modernas. Este trabajo introduce un sistema de monitoreo multivariable y modular (EMM) diseñado para AWEs de baja escala (hasta 2.5 kW), que incorpora una interfaz gráfica de usuario para facilitar una operación eficiente y segura. El EMM monitoriza en tiempo real las variables críticas incluyendo temperatura (T), presión (P), flujo de hidrógeno (Fh), voltaje (Vy), y corriente (C), lo que permite adaptaciones dinámicas a las condiciones operativas. Durante las pruebas, el sistema demostró un incremento del 250 % en la producción de hidrógeno al ajustar la temperatura en un 60 % y la presión en un 10 %. El diseño compacto del EMM, con dimensiones de 14 cm x 5 cm x 15 cm y un peso de 2 kg, junto con su capacidad de operar autónomamente por 18 horas, subrayan su aplicabilidad en diversos entornos operativos. Estos resultados destacan la importancia de sistemas de monitoreo integrados y adaptativos en la optimización de la producción de hidrógeno y la integración de AWEs con las redes de energía renovable.This study emphasizes the importance of transitioning to renewable energies through the deployment of alkaline water electrolyzers (AWEs) for green hydrogen production. AWEs, since their introduction in the 18th century, have evolved from initial capacities of 0.08 Nm³/h to modern industrial configurations reaching up to 1,200 Nm³/h. This work introduces a multivariable and modular monitoring system (EMM) designed for low-scale AWEs (up to 2.5 kW), incorporating a graphical user interface to facilitate efficient and safe operation. The EMM monitors critical variables in real-time including temperature (T), pressure (P), hydrogen flow (Fh), voltage (Vy), and current (C), allowing dynamic adaptations to operational conditions. During testing, the system demonstrated a 250 % increase in hydrogen production by adjusting the temperature by 60 % and the pressure by 10 %. The compact design of the EMM, with dimensions of 14 cm x 5 cm x 15 cm and a weight of 2 kg, along with its capability to operate autonomously for 18 hours, underscore its applicability in various operational environments. These results highlight the importance of integrated and adaptive monitoring systems in optimizing hydrogen production and integrating AWEs with renewable energy networks.Pregrad
Point-to-point readout for the ALICE EMCal detector
No full textAbstractIt is anticipated that the LHC will deliver Pb+Pb collisions at a minimum bias interaction rate of about 50kHz after the second long shutdown of the LHC in 2018. This will be roughly two orders of magnitude greater than the current data recording rate capability of the ALICE experiment. Therefore a major upgrade of the ALICE detector is planned for the next shutdown to enable ALICE to record data at the full Pb+Pb minimum bias interaction rate delivered by the LHC. A new point-to-point readout system for the electromagnetic calorimeter (EMCal) of ALICE has been developed, to replace the legacy readout bus, that essentially accomplishes this goal, and is being installed during the current LHC shutdown (2013–2014). The new readout uses the existing EMCal front end electronics yet provides more than an order of magnitude decrease in the readout time, to about 21μs, with modest cost and effort
Characterization of a new charge sensitive preamplifier (CSP) for the electromagnetic calorimeters of the ALICE experiment
No full textThe ALICE calorimeters PHOS and EMCal (including its extension DCal) are based on Avalanche Photo-Diode (APD) photosensors with Charge Sensitive Preamplifiers (CSPs) for readout of the scintillating elements. A new CSP has been developed on the basis of the design of the PHOS CSP, but modified to meet the requirements of the EMCal and DCal. Modifications were made specifically for a different APD choice with different characteristics, and also with the goals of less noise, faster rise time, and reduced cost. This paper presents a detailed description of the new CSP features and the test results
Spectra and ratios of identified particles in Au plus Au and d plus Au collisions at root s(NN)=200 GeV
No full textThe transverse momentum (p(T)) spectra and ratios of identified charged hadrons (pi(+/-), K-+/-, p, (p) over bar) produced in root s(NN) = 200 GeV Au + Au and d + Au collisions are reported in five different centrality classes for each collision species. The measurements of pions and protons are reported up to p(T) = 6 GeV/c (5 GeV/c), and the measurements of kaons are reported up to p(T) = 4 GeV/c (3.5 GeV/c) in Au + Au (d + Au) collisions. In the intermediate p(T) region, between 2 and 5 GeV/c, a significant enhancement of baryon-to-meson ratios compared to those measured in p + p collisions is observed. This enhancement is present in both Au + Au and d + Au collisions and increases as the collisions become more central. We compare a class of peripheral Au + Au collisions with a class of central d + Au collisions which have a comparable number of participating nucleons and binary nucleon-nucleon collisions. The p(T)-dependent particle ratios for these classes display a remarkable similarity, which is then discussed.Physics, NuclearSCI(E)0ARTICLE2null8
Azimuthal anisotropy of pi(0) and eta mesons in Au plus Au collisions at root s(NN)=200 GeV
No full textThe azimuthal anisotropy coefficients v2 and v4 of p 0 and. mesons are measured in Au + Au collisions at root s(NN) = 200 GeV as a function of transverse momentum p(T) (1-14 GeV/c) and centrality. The extracted v(2) coefficients are found to be consistent between the two meson species over the measured p(T) range. The ratio of v(4)/v(2)(2) for pi(0) mesons is found to be independent of p(T) for 1- 9 GeV/c, implying a lack of sensitivity of the ratio to the change of underlying physics with p(T). Furthermore, the ratio of v(4)/v(2)(2) is systematically larger in central collisions, which may reflect the combined effects of fluctuations in the initial collision geometry and finite viscosity in the evolving medium.Physics, NuclearSCI(E)0ARTICLE6null8
Heavy-flavor electron-muon correlations in p plus p and d plus Au collisions at root s(NN)=200 GeV
No full textBackground: Heavy-flavor modification in relativistic p(d) + A collisions are sensitive to different kinds of strong-interaction physics ranging from modifications of the nuclear wave function to initial- and final-state energy loss. Modifications to single heavy-flavor particles and their decay leptons at midrapidity and forward rapidity are well established at the Relativistic Heavy Ion Collider (RHIC). Purpose: This paper presents measurements of azimuthal correlations of electron-muon pairs produced from heavy-flavor decays, primarily c (c) over bar, in root s(NN) = 200 GeV p + p and d + Au collision using the PHENIX detector at RHIC. The electrons are measured at midrapidity while the muons in the pair are measured at forward rapidity, defined as the direction of the deuteron beam, in order to utilize the deuteron to probe low-x partons in the gold nucleus. Methods: This analysis uses the central spectrometer arms for electron identification and forward spectrometer arms for muon identification. Azimuthal correlations are built in all sign combinations for e-mu pairs. Subtracting the like-sign yield from the unlike-sign yield removes the correlations from light flavor decays and conversions. Results: Comparing the p + p results with several different Monte Carlo event generators, we find the results are consistent with a total charm cross section sigma(c (c) over bar) = 538 +/- 46 (stat) +/- 197 (data syst) +/- 174 (model syst) mu b. These generators also indicate that the back-to-back peak at Delta phi = pi is dominantly from the leading-order contributions (gluon fusion), while higher-order processes (flavor excitation and gluon splitting) contribute to the yield at all Delta phi. We observe a suppression in the pair yield per collision in d + Au. We find the pair yield suppression factor for 2.7 < Delta phi < 3.2 rad is J(dA) = 0.433 +/- 0.087 (stat) +/- 0.135 (syst). Conclusions: The e-mu pairs result from partons at x(Au) similar to 10(-2) at Q(2) = 10 GeV/c(2) at the edge of the shadowing region. The pair suppression indicates modification to c (c) over bar pairs for these kinematics in the cold nuclear medium at RHIC.Physics, NuclearSCI(E)[email protected]; [email protected]
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