The measurement of the production of charm jets, identified by the presence of a D$^{0}$ meson in the jet constituents, is presented in proton–proton collisions at centre-of-mass energies of $ ...\sqrt{s} $ = 5.02 and 13 TeV with the ALICE detector at the CERN LHC. The D$^{0}$ mesons were reconstructed from their hadronic decay D$^{0}$ → K$^{−}$π$^{+}$ and the respective charge conjugate. Jets were reconstructed from D$^{0}$-meson candidates and charged particles using the anti-k$_{T}$ algorithm, in the jet transverse momentum range 5 < p$_{T,chjet}$< 50 GeV/c, pseudorapidity |η$_{jet}$| < 0.9 − R, and with the jet resolution parameters R = 0.2, 0.4, 0.6. The distribution of the jet momentum fraction carried by a D$^{0}$ meson along the jet axis $ \left({z}_{\Big\Vert}^{\textrm{ch}}\right) $ was measured in the range 0.4 <$ {z}_{\Big\Vert}^{\textrm{ch}} $< 1.0 in four ranges of the jet transverse momentum. Comparisons of results for different collision energies and jet resolution parameters are also presented. The measurements are compared to predictions from Monte Carlo event generators based on leading-order and next-to-leading-order perturbative quantum chromodynamics calculations. A generally good description of the main features of the data is obtained in spite of a few discrepancies at low p$_{T,chjet}$. Measurements were also done for R = 0.3 at $ \sqrt{s} $ = 5.02 and are shown along with their comparisons to theoretical predictions in an appendix to this paper.graphic not available: see fulltext
A broad-spectrum self-excited dust density wave is experimentally studied in a vertically extended nanodusty plasma consisting of in situ grown carbonaceous nanometer sized particles. The nanodusty ...plasma having high particle density (of the order of 10^12-10^13 m^(-3)) is created with vertical extension up to (40+-0.1) cm and radial extension up to (5+-0.1) cm. The propagation of the self-excited dust density wave under strong Havnes effect is examined over a large axial distance (19+-0.1) cm. Time-resolved Hilbert transformation and Fast Fourier transformation techniques are used to study the spatiotemporal evolution of frequency and wave numbers along three directions from the dust void viz. axial, radial and oblique. The propagation is found to be inhomogeneous throughout the dust cloud. The phase velocity of the wave is estimated to be quite low and decreasing along the direction of propagation. This effect is attributed to the strong reduction of particle charge due to a high Havnes parameter along the propagation direction. By the estimation of average particle charge, ion density and the finite electric field throughout the nanodust cloud, a quantitative analysis of the void formation in nanodusty plasma is presented. New insights are also made regarding wave merging phenomena using time-resolved Hilbert transformation.
The experimental observation of Peregrine solitons in a multicomponent plasma with the critical concentration of negative ions is reported. A slowly amplitude modulated perturbation undergoes ...self-modulation and gives rise to a high amplitude localized pulse. The measured amplitude of the Peregrine soliton is 3 times the nearby carrier wave amplitude, which agrees with the theory. The numerical solution of the nonlinear Schrödinger equation is compared with the experimental results.
The evolution of the multi-Peregrine soliton is investigated in a multicomponent plasma and found to be critically dependent on the initial bound state. Formation and splitting of Peregrine soliton, ...broadening of the frequency spectra provide clear evidence of nonlinear-dispersive focusing due to modulational instability, a generic mechanism for rogue wave formation in which amplitude and phase modulation grow as a result of interplay between nonlinearity and anomalous dispersion. We have shown that initial perturbation parameters (amplitude & temporal length) critically determine the number of solitons evolution. It is also found that a sufficiently long wavelength perturbation of high amplitude invoke strong nonlinearity to generate a supercontinuum state. Continuous Wavelet Transform (CWT) and Fast Fourier Transform (FFT) analysis of the experimental time series data clearly indicate the spatio-temporal localization and spectral broadening. We consider a model based on the frame work of Nonlinear Schrodinger equation (NLSE) to explain the experimental observations.
•The observation of multi-Peregrine soliton in multicomponent plasma is reported.•NLSE supports the evolution due to modulational instability of ion acoustic wave.•Soliton evolution and fission critically depend upon the initial perturbation.•Soliton fission and spectral broadening exhibit nonlinear dispersive self-focusing.
The electric charge on silica microparticles (5 µm in diameter) levitating in the sheath of an rf discharge plasma is determined in a newly installed device for dusty plasma experiments at the IASST. ...The sheath potential profile is measured using an emissive probe and the electric field is obtained in order to determine the dust charge. The measured dust charge in the pressure range 0.50-5.0 Pa using the electric field value at the levitation height is found to be of the order of 104 elementary charges. Dust charge is also examined using the vertical resonance method which gives a similar order of charges. The experimentally measured charge is compared with the estimated values based on the orbital motion limited charging model. The coupling strength between the particles forming a 2D plasma crystal lattice is estimated using the measured dust charge.
A magnetic filter plasma source has been designed to produce a low electron temperature (Te ~ 0.15 eV) and low electron density (ne ~ 106 cm-3) plasma volume. The parameters Te and ne are found to be ...controllable within a certain range by adjusting the discharge condition in the source. Charging of micrometre-sized dust grains in such a plasma has been investigated. The measured average charge on a dust grain (a few hundred electrons) is found to be very close to that observed in nature. When dust grains are allowed to enter perpendicularly into an external axial magnetic field applied to such a plasma, the average grain charge increases with increasing strength of the magnetic field (<150 G).
We report the observation of nonlinear propagation of ion acoustic wave packet in multi-component plasma with negative ions. The wavepacket which is purely amplitude modulated is found to undergo ...steepening leading to formation of a solitary pulse like structure. At large wave amplitude (
∂n
n
= 20%
) the wavepacket splits into two parts during propagation.
