128 research outputs found
CW Pump Fluid Induced Vibration Troubleshooting Methodology
No full textAbstractFluid-machines experience a variety of forces during their operation result in different type of dynamic vibration behavior. Fluid induced instability phenomena are one such issue that typically manifests itself as a large amplitude sub-synchronous vibration of the pump shaft and pump structure due to whirl or vortex. When a pump is not operated at its Best Efficiency Point the part of mechanical energy is transferred to the fluid that develops Vortices. It occur in shear layers between the main flow and the re-circulating fluid. This rotating fluid (Vortex) having very low pressure in its centre and forms vapor bubbles at very high rate this vapor bubbles formation and collapse (cavitation) produce hammering effect that begins to participate in the system dynamics and can lead to fluid induced vibration and sound under certain machine state & operating regime favorable to the same. It should be avoided as it can lead to machine failures due to stress-cycle fatigu
The polarized deuteron target at COMPASS in 2022
No full textThe COMPASS experiment at CERN used a upgraded transversely polarized deuteron target with a muon beam of 160 GeV/c for SIDIS measurements in 2022. The deuteron target material of 6LiD installed in 3 cells was polarized by the DNP method with a 2.5 T magnet, a dilution refrig- erator and three 70 GHz microwave oscillators. During the data-taking the target operates in a transversely oriented magnetic dipole field at 0.6 T. This frozen spin operation mode without DNP process leads to a slow depolarization. Nevertheless, it was important to reach 40 % polarization that is sufficient for spin asymmetry measurement. The newly installed 3 microwave oscillators played a significant role to increase the polarization. We obtained deuteron polarizations of more than 40 % in each cell for two days. The relaxation time of the deuteron polarizations during the data taking period was measured to be about 5000 h at 0.6 T and below 100 mK
Nanodiamond photocathodes for MPGD-based single photon detectors at future EIC
Get PDFWe are developing gaseous photon detectors for Cherenkov imaging applications in the experiments at the future Electron Ion Collider. CsI, converting photons in the far ultraviolet range, is, so far, the only photoconverter compatible with the operation of gaseous detectors. It is very delicate to handle due to its hygroscopic nature: the absorbed water vapour decomposes the CsI molecule. In addition, its quantum efficiency degrades under ion bombardment. These are the key reasons to quest for novel, less delicate materials for photocathodes adequate for gaseous photon detectors. Layers of hydrogenated nanodiamond particles have recently been proposed as an alternative material and have shown promising characteristics. The performance of nanodiamond photocathodes coupled to thick GEM-based detectors is the objects of our ongoing R&D. The first phase of these studies includes the characterization of thick GEM coated with nanodiamond layers and the robustness of its photoconverting properties with respect to the bombardment by ions from the multiplication process in the gaseous detector. The approach is described in detail as well as all the results obtained so far within these exploratory studies
Cultura e società in India
Get PDFIl volume offre in forma sintetica e accessibile tutte le informazioni necessarie per capire l’India contemporanea: accanto ai capitoli sulla politica e l’economia, sulla società e la religione, il lettore troverà dunque saggi dedicati alla poesia e alla narrativa, alla pittura e all’architettura, al cinema e al teatro.- Indice #9- Prefazione, Marcello Pacini #13- La cultura politica dello Stato indiano, Ashis Nandy #17- Il passato e il presente: un dialogo indiano, Ravinder Kumar #43- L’impresa indiana oggi, Rajni Kothari #65- Libertà di vignetta, libertà di parola, R. K. Laxman #81- Il pubblico, il privato e il sacro, Charles Correa #105- La religione in India, T. N. Madan #125- Autorità e identità in India, T. G. Vaidyanathan #155- La pittura indiana contemporanea, Gieve Patel #179- La narrativa indiana contemporanea, Anita Desai #213-Un’intervista con R. K. Narayan, Stephen R. Graubard #243- Raccontar fiabe, A. K. Ramanujan #249- Voci di bambini, Veena Das #271- Sedici poesie indiane moderne a cura di Vinay Dhanoadker e A. K. Ramanujan #301- Il teatro in India, Girish Karnad #331- L’India, gli indiani e la scienza, Pushpa M. Bhargava e Chandana Chakrabarti #353- Lo sviluppo dell’India: ammaestramenti, Amartya K. Sen #365- Glossario #389- Cronologia #415- Bibliografia #48
D0-meson-tagged jet axes difference in proton-proton collisions at sqrt(s) = 5.02 TeV
No full textHeavy-flavor quarks produced in proton-proton (pp) collisions provide a unique opportunity to
investigate the evolution of quark-initiated parton showers from initial hard scatterings to final-state
hadrons. By examining jets that contain heavy-flavor hadrons, this study explores the effects of both
perturbative and nonperturbative QCD on jet formation and structure. The angular differences between
various jet axes, ΔRaxis , offer insight into the radiation patterns and fragmentation of charm quarks. The
first measurement of D0-tagged jet axes differences in pp collisions at ffiffiffi
s
p 1⁄4 5.02 TeV by the ALICE
experiment at the LHC is presented for jets with transverse momentum pch jet
T ≥ 10 GeV=c and D0 mesons
with pD0
T ≥ 5 GeV=c. In this D0-meson-tagged jet measurement, three jet axis definitions, each with
different sensitivities to soft, wide-angle radiation, are used: the standard axis, soft drop groomed axis, and
winner-takes-all axis. Measurements of the radial distributions of D0 mesons with respect to the jet axes,
ΔRaxis-D0 , are reported, along with the angle, ΔRaxis , between the three jet axes. The D0 meson emerges as
the leading particle in these jets, closely aligning with the winner-takes-all axis and diverging from the
standard jet axis. The results also examine how varying the sensitivity to soft radiation with grooming
influences the orientation of the soft drop jet axis and uncover that charm-jet structure is more likely to
survive grooming when the soft drop axis is further from the D0 direction, providing further evidence of the
dead-cone effect recently measured by ALICE
Coherent J/ψ photoproduction at midrapidity in Pb−Pb collisions at sNN=5.02 TeV
No full textThe coherent J/ ψ photoproduction cross section is measured for the first time at midrapidity in peripheral to semicentral Pb−Pb collisions at sNN=5.02 TeV. The centrality differential cross section d σ /d y is reported for the centrality range 40–90%, together with the doubly-differential cross section d2 σ /d y d p T, extracted in two peripheral centrality classes. The J/ ψ mesons are reconstructed in the dielectron channel, in the rapidity interval | y | < 0.9 using the ALICE central barrel detectors. The J/ ψ cross section at midrapidity is statistically compatible to the earlier ALICE measurement at forward rapidity and at the same centre-of-mass energy, and shows only a mild centrality dependence over the covered range. Several sets of theoretical calculations taking into account the hadronic overlap in the collisions but ignoring possible final-state effects from a hot expanding medium are found to give a fairly good description of the current measurements within uncertainties
Femtoscopic study of the proton-proton and proton-deuteron systems in heavy-ion collisions at the LHC
No full textThis work reports femtoscopic correlations of p-−p(p ̅-−p ̅) and p−−d(p ̅-−d ̅) pairs measured in Pb–Pb collisions at center-of-mass energy per nucleon sNN = 5.02 TeV in the ALICE Collaboration. A fit to the measured proton-proton correlation functions allows one to extract the dependence of the nucleon femtoscopic radius of the particle-emitting source on the pair transverse mass (mT) and on the average charge particle multiplicity 〈dNch/dη〉1/3 for three centrality intervals (0–10%,10−−30%,30−−50%). In both cases, the expected power-law and linear scalings are observed, respectively. The measured p–d correlations can be described by both two- and three-body calculations, indicating that the femtoscopy observable is not sensitive to the short-distance features of the dynamics of the p-(p-n) system, due to the large inter-particle distances in Pb–Pb collisions at the LHC. Indeed, in this study, the minimum measured femtoscopic source sizes for protons and deuterons have a minimum value at 2.73−0.05+0.05 and 3.10−0.86+1.04 fm, respectively, for the 30–50% centrality collisions. Moreover, the m T-scaling obtained for the p–p and p–d systems is compatible within 1 σ of the uncertainties. These findings provide new input for fundamental studies on the production of light (anti)nuclei under extreme conditions
Search for Quasiparticle Scattering in the Quark-Gluon Plasma with Jet Splittings in <i>pp</i> and Pb-Pb Collisions at √<i>S</i><sub>NN</sub>=5.02 TeV
No full textThe ALICE Collaboration reports measurements of the large relative transverse momentum (k(T)) component of jet substructure in pp and Pb-Pb collisions at center-of-mass energy per nucleon pair root S-NN = 5.02 TeV. Enhancement in the yield of such large-k(T) emissions in head-on Pb-Pb collisions is predicted to arise from partonic scattering with quasiparticles of the quark-gluon plasma. The analysis utilizes charged-particle jets reconstructed by the anti-kT algorithm with resolution parameter R = 0.2 in the transverse-momentum interval 60 < p(T,ch,jet) < 80 GeV/c. The soft drop and dynamical grooming algorithms are used to identify high transverse momentum splittings in the jet shower. Comparison of measurements in Pb-Pb and pp collisions shows medium-induced narrowing, corresponding to yield suppression of high-k(T) splittings, in contrast to the expectation of yield enhancement due to quasiparticle scattering. The measurements are compared to theoretical model calculations incorporating jet modification due to jet-medium interactions ("jet quenching"), both with and without quasiparticle scattering effects. These measurements provide new insight into the underlying mechanisms and theoretical modeling of jet quenching
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