An X-ray interferometry technique using an X-ray microfocus laboratory source for thin-film structure research based on compound refractive lenses has been proposed. The main advantage of this ...technique is to use a very simplified experimental setup where a focused X-ray beam reflected from parallel flat surfaces creates an interference pattern in a wide angular range. Due to this, the interference pattern can be obtained in a single shot without the need to rotate the specimen or the detector. The applicability of this technique has been demonstrated using the MetalJet Excillium micro-focus laboratory source, which has GaKα emission line at 9.25 keV. As a result, a series of interference patterns for test sample a free-standing thin-film membrane, thickness 500 nm, was observed. Based on the obtained results the main advantages of this technique such as high spatial and temporal resolution are shown, and also possible application of the reflecto-interferometry both at the laboratory and synchrotron radiation X-ray sources are proposed.
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High-accuracy and high-luminosity measurements of anisotropic flow for various hadron types over full NICA energy range will provide important constraints on the early dynamics of heavy-ion ...reactions under the conditions where a first-order quark-hadron phase transition may occur. The statistical reach for elliptic flow measurements at NICA is estimated with HYDJET++ heavy-ion event generator.
The production of same-sign W-boson pairs from double parton scatterings (DPS) in proton–lead (p–Pb) collisions at the CERN Large Hadron Collider is studied. The signal and background cross sections ...are estimated with next-to-leading-order perturbative QCD calculations using nuclear parton distribution functions for the Pb ion. At sNN=8.8 TeV the cross section for the DPS process is about 150 pb, i.e. 600 times larger than that in proton–proton collisions at the same centre-of-mass energy and 1.5 times higher than the p–Pb→W±W±+2-jets single-parton background. The measurement of such a process, where 10 events with fully leptonic Wʼs decays are expected after cuts in 2 pb−1, would constitute an unambiguous DPS signal and would help determine the effective σeff parameter characterising the transverse distribution of partons in the proton.
It is shown that the factorization hypothesis, which is usually applied to two-parton distributions at the present time in analyzing experimental data on double parton scattering, is in an obvious ...contradiction with the QCD evolution equations. The predictions of QCD for basic properties of two-parton distribution are discussed.
Nuclear geometry of jet quenching Lokhtin, I.P.; Snigirev, A.M.
The European physical journal. C, Particles and fields,
09/2000, Letnik:
16, Številka:
3
Journal Article
Recenzirano
Odprti dostop
The most suitable way to study jet quenching as a function of the distance traversed is varying the impact parameter b of the ultrarelativistic nucleus–nucleus collision (the initial energy density ...in the nuclear overlapping zone is almost independent of b up to \(b \sim R_A\)). It is shown that the b-dependences of the medium-induced radiative and collisional energy losses of a hard parton jet propagating through dense QCD matter are very different. The experimental verification of this phenomenon could be performed for a jet with non-zero cone size based on the essential difference between the angular distributions of the collisional and radiative energy losses.
Fluctuations of anisotropic flow in lead-lead collisions at LHC energies arising in HYDJET++model are studied. It is shown that intrinsic fluctuations of the flow which appear mainly because of the ...fluctuations of particle multiplicity, momenta and coordinates are insufficient to match the measured experimental data, provided the eccentricity of the freeze-out hypersurface is fixed at any given impact parameter b. However, when the variations of the eccentricity in HYDJET++ are taken into account, the agreement between the model results and the data is drastically improved. Both model calculations and the data are filtered through the unfolding procedure. This procedure eliminates the non-flow fluctuations to a higher degree, thus indicating a dynamical origin of the flow fluctuations in HYDJET++ event generator.
•· The paper presents studies of deposits produced by QSPA-Be machine. · Characterization of the deposits revealed PC-BeO stricture of the films. · The deposits were found to be ...similar to those obtained in JET-ILW outer divertor.· The one pulse of QSPA-Be provided deposition of ∼7 nm contaminant layer. · Test plasma cleaning of DTS protective window mock-ups is discussed.
Studies of contaminants obtained by spraying ITER-grade Be on a quasi-stationary plasma gun facility QSPA-Be are presented. Contaminating films, consisting mainly of Be and O in approximately equal proportions, were deposited on substrates of quartz, sapphire, single crystalline silicon (SC-Si) and NaCl crystal. Characterization of the deposits was performed using SEM, XPS, EBS, AFM, SE, TEM&SAED and micro-interferometry showing polycrystalline BeO films similar as found in JET-ILW. Films on SC-Si and NaCl were used to characterize their composition and morphology. The cleaning rates in the 81.36 MHz RF discharges in He or D2 at 2 Pa were measured on the SC-Si target. The measured etching rate of the deposited films was several times higher than the rate calculated from the theoretical value of beryllium oxide sputtering yield. Test cleaning of these contaminants was carried out in a capacitively coupled RF discharge (CCRF) from the surface of sapphire and quartz plates, which were considered as a mock-ups of the protective window of the first mirror unit (FMU) designed for ITER divertor Thomson scattering diagnostic system (DTS).
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