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Register a new userMesonic Super v{C}erenkov-like effects in hadronic and nuclear media
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Generalized mesonic Super-v{C}erenkov Radiations (Sv{C}R) are investigated. The energy behavior of the pionic refractive index in the low energy pionic SCR-sector is presented. We estimated that the true coherent SCR-pion emission is possible mainly in the SCRS-energy bands 190-315 MeV for all pions; 910-960 MeV only for positive pions, and 80-1000 GeV for all pions, in certain nuclear reactions. We predicted that Sv{C}R-pionic band will be enlarged for the pion energies higher than 80 GeV. The strong correlations between angle of SCR-pion emission and (meson and projectile)-energies are evidentiated. The spectral distributions of the SCR-pions are presented and the position of their maxima are estimated. The agreement with the available experimental data is discussed.
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Generalized Super-v{C}erenkov Radiations (Sv{C}R), as well as their Sv{C}R-signatures are investigated. Two general Sv{C}R-coherence conditions are found as two natural extremes of the same spontaneous particles decays in (dielectric, nuclear or hadronic) media. The main results on the experimental test of the super-coherence conditions, obtained by using the experimental data from BNL, are presented. The interpretation of the observed anomalous v{C}erenkov rings as experimental evidence for the HE-component of the Sv{C}R is discussed.
We report on the design, construction, commissioning, and performance of a threshold gas v{C}erenkov counter in an open configuration, which operates in a high luminosity environment and produces a high photo-electron yield. Part of a unique open geometry detector package known as the Big Electron Telescope Array, this v{C}erenkov counter served to identify scattered electrons and reject produced pions in an inclusive scattering experiment known as the Spin Asymmetries of the Nucleon Experiment E07-003 at the Thomas Jefferson National Accelerator Facility (TJNAF) also known as Jefferson Lab. The experiment consisted of a measurement of double spin asymmetries $A_{parallel}$ and $A_{perp}$ of a polarized electron beam impinging on a polarized ammonia target. The v{C}erenkov counters performance is characterised by a yield of about 20 photoelectrons per electron or positron track. Thanks to this large number of photoelectrons per track, the v{C}erenkov counter had enough resolution to identify electron-positron pairs from the conversion of photons resulting mainly from $pi^0$ decays.
The properties of the nuclear isoscaling at finite temperature are investigated and the extent to which its parameter $alpha$ holds information on the symmetry energy is examined. We show that, although finite temperature effects invalidate the analytical formulas that relate the isoscaling parameter $alpha$ to those of the mass formula, the symmetry energy remains the main ingredient that dictates the behavior of $alpha$ at finite temperatures, even for very different sources. This conclusion is not obvious as it is not true in the vanishing temperature limit, where analytical formulas are available. Our results also reveal that different statistical ensembles lead to essentially the same conclusions based on the isoscaling analysis, for the temperatures usually assumed in theoretical calculations in the nuclear multifragmentation process.
We use a three-body Continuum Discretized Coupled Channel (CDCC) model to investigate Coulomb and nuclear effects in breakup and reaction cross sections. The breakup of the projectile is simulated by a finite number of square integrable wave functions. First we show that the scattering matrices can be split in a nuclear term, and in a Coulomb term. This decomposition is based on the Lippmann-Schwinger equation, and requires the scattering wave functions. We present two different methods to separate both effects. Then, we apply this separation to breakup and reaction cross sections of 7Li + 208Pb. For breakup, we investigate various aspects, such as the role of the alpha + t continuum, the angular-momentum distribution, and the balance between Coulomb and nuclear effects. We show that there is a large ambiguity in defining the Coulomb and nuclear breakup cross sections, since both techniques, although providing the same total breakup cross sections, strongly differ for the individual components. We suggest a third method which could be efficiently used to address convergence problems at large angular momentum. For reaction cross sections, interference effects are smaller, and the nuclear contribution is dominant above the Coulomb barrier. We also draw attention on different definitions of the reaction cross section which exist in the literature, and which may induce small, but significant, differences in the numerical values.
A unified theoretical model reproducing charge radii of known atomic nuclei plays an essential role to make extrapolations in the regions of unknown nuclear size. Recently developed new ansatz which phenomenally takes into account the neutron-proton short-range correlations (np-SRCs) can describe the discontinuity properties and odd-even staggering (OES) effect of charge radii along isotopic chains remarkably well. In this work, we further review the modified rms charge radii formula in the framework of relativistic mean field (RMF) theory. The charge radii are calculated along various isotopic chains that include the nuclei featuring the $N=50$ and $82$ magic shells. Our results suggest that RMF with and without considering correction term give almost similar trend of nuclear size for some isotopic chains with open proton shell, especially the shrink phenomena of charge radii at strong neutron closed shells and the OES behaviors. This suggests that the np-SRCs has almost no influence for some nuclei due to the strong coupling between different levels around Fermi surface. The weakening OES behavior of nuclear charge radii is observed generally at completely filled neutron shells and this may be proposed as a signature of magic indicator.
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