Appearance / Disappearance of Magic Number in Light Nuclei

The shell structure of a nucleus is important to study their observed characteristic features. The classic magic numbers are successful in explaining the nuclear properties for nuclei lying near the stability line. The advent of radioactive ion beam facilities has permitted to examine nuclei in their extreme proton to neutron ratio. The light exotic nuclei were found to exhibit unique shell closure behaviour which is different from the medium mass nuclei near the stability line. The two nucleon separation energy difference systematics was used as a probe to study the magic character of light nuclei. New proton and neutron magic numbers were predicted among the available even Z isotopes and even N isotones. For certain systems, the classic magic numbers were found to be non-magic, while for some systems the magic property is retained even at the drip lines. The shell closure behaviour predicted is found to depend on the version of the mass table.

Supercritical behavior of magnetic and liquid model systems

The supercritical transitions are widely occurring. They include the supercritical transitions in the liquid-vapor system, ferromagnetic transitions, transitions in polymers, many transitions in liquid crystals, and some structural transitions. In the paper it is emphasized that the nature of the critical and supercritical transitions is the same – these are continuous fluctuation transitions. Above the critical temperature the system passes through a region of lowered stability, which leads to increase of fluctuations of energy and external parameters of the system. From the point of view of thermodynamic stability this indicates the existence of a continuous supercritical transition between supercritical mesophases. Knowing the basic stability characteristics of a system, we derive the equation of these mesophase transitions. Depending on a thermal equation type, we can get one or several such equations, which may not coincide. This approves the fact that a supercritical transition occurs in a certain interval of thermodynamic forces. In the paper the relations between the critical exponents of thermodynamic parameters of the system are obtained and the conditions of continuous conjugation of the lowered stability line to subcritical coexistence line are investigated. The results are applied to the Curie–Weiss and van der Waals models: we obtain the quasi-spinodal equation for these systems and analyze the critical and supercritical behavior of the stability characteristics.

Theoretical progress on production of isotopes in the multinucleon transfer process

As one promising approach for producing nuclei beyond the [Formula: see text]-stability line, the multinucleon transfer (MNT) process has been extensively investigated in past decades. An overview of the theoretical progress on production of isotopes in MNT process is presented. The dinuclear system model, one hybrid approach (GRAZING+DNS model), the improved quantum molecule dynamic model, and the model based on the Langevin equations are summarized. The nucleon transfer mechanisms, such as effects of quasi-elastic and deep inelastic collisions, energy dissipation, [Formula: see text] equilibration, and shell structure in collisions of two complex nuclei are discussed. We present the progress on production of the exotic nuclei near the neutron-drip line, the neutron-rich isotopes near [Formula: see text], and the transuranium nuclei.

Collisionless electron dynamics in the expanding solar wind

<p><span>Observations of solar wind electron properties, as displayed in the T</span><sub><span>perp</span></sub><span>/T<sub>par</sub> vs β<sub>par</sub> plane, appear to be constrained both in the T<sub><span>perp</span></sub>/T<sub>par</sub></span><span> <1 and in the T<sub><span>perp</span></sub>/T<sub>par</sub></span><span> >1 regimes by the electron firehose instability (EFI) and by the whistler instability respectively [</span><span>Štverák 2008</span><span>]. The onset mechanism of the EFI is established: solar wind expansion results in an electron thermal anisotropy, which in turns promotes the development of the instability that contributes to limit that same anisotropy [Innocenti 2019a]. However, if this were the only mechanism at work in the expanding solar wind, electron observations would pool at the EFI marginal instability line. Instead, they populate the “stable” interval bound by EFI and whistler marginal instability lines. It is not fully clear which role fully kinetic processes have in lifting the observed data points above the EFI marginal stability line and into the “stable” area. Other competing processes redistributing excess parallel energy into the perpendicular direction, such as collisions, may be at work as well [Yoon 2019].</span></p><p><span>We investigate this issue with Particle In Cell, Expanding Box Model<span>  </span>simulations [Innocenti 2019b] of EFI developing self consistently in the expanding solar wind. Our results show that after the EFI marginal stability line is reached, further collisionless evolution brings our simulated data points in the “stable” area. We thus demonstrate that, at least under certain circumstances, purely collisionless processes may explain observed solar wind observations, without the need of invoking collisions as a way to channel excess parallel energy into the perpendicular direction.</span></p><p> </p><p><span>Štverák, Štěpán, et al. "Electron temperature anisotropy constraints in the solar wind." <em>Journal of Geophysical Research: Space Physics</em> 113.A3 (2008).</span></p><p><span>Innocenti, Maria Elena, et al. "Onset and Evolution of the Oblique, Resonant Electron Firehose Instability in the Expanding Solar Wind Plasma." <em>The Astrophysical Journal</em> 883.2 (2019): 146.</span></p><p><span>Yoon, P. H., et al. "Solar Wind Temperature Isotropy." <em>Physical review letters</em> 123.14 (2019): 145101.</span></p><p><span>Innocenti, Maria Elena, Anna Tenerani, and Marco Velli. "A Semi-implicit Particle-in-cell Expanding Box Model Code for Fully Kinetic Simulations of the Expanding Solar Wind Plasma." <em>The Astrophysical Journal</em> 870.2 (2019): 66.</span></p>

KdV–Berger solution and local cluster effect of two-sided lateral gap continuum traffic flow model

This study proposes a new nonlane-based continuum model derived from a two-sided lateral gap-following theory using the relation between microscopic and macroscopic variables. The model considers the effect of lateral gaps of the leading vehicles available on both sides of the following vehicle in multilane scenario. Linear stability analysis is performed to establish the neutral stability condition for the stable traffic flow. Nonlinear analysis is carried out at neutral stability line to derive the KdV–Berger equation, which describes density wave propagation. For that, one of the traveling wave solutions is also obtained. Numerical simulation results show that the two-sided lateral gap in the model improves the stability of the traffic flow by suppressing the traffic jams even at high-density conditions. The results implies that the proposed model is successful in replicating the properties of actual traffic jams in nonlane-based traffic environment.

Direct measurement of fission barrier height of unstable heavy nuclei at ISOL facilities

Fission barrier height is one of the least known nuclear parameters, with experimental data, acquired decades ago, existing only close to beta-stability line. Availability of heavy radioactive beams offers possibility to investigate fission of more exotic nuclei and using the state of the art detection technique such as the active target we can even probe their fission barriers heights with precision has not been reached so far. The present status of fission barrier measurement is going to be explained in this paper. We are going to discuss the possibilities to stage experimental studies of fission barrier heights at new generation of ISOL facilities such as HIE-ISOLDE and active target ACTAR TPC. As an example we select the experiment IS581, being prepared for execution at the HIE-ISOLDE facility (CERN).

Study of Grodzins relation of B(E2) with E(21+) in A = 130, 100 and 80 regions

The nuclei in the [Formula: see text] [Formula: see text] and [Formula: see text] regions, lying on both sides of the [Formula: see text]-stability line, continue to be of interest for their complex nuclear structures. The Grodzins product rule (GPR) viz. [Formula: see text], for the ground bands of even-[Formula: see text] even-[Formula: see text] nuclei provides a useful approach to study these structures. The utility of our method, displaying the linear relation of [Formula: see text] to [Formula: see text], is illustrated for the [Formula: see text] Zn to [Formula: see text] Cd series of isotopes. The spread of the data on the linear plots enables a quick view of the shape phase transitions. The role of the shells and the subshells, at spherical and deformed shell gaps for neutrons and protons, with their mutual re-inforcement and the shape phase transition are vividly visible on our plots. The development of collectivity in this region is also linked to the effective number of valence nucleons above the magic number of [Formula: see text], and 28 rather than [Formula: see text], for Mo to Cd isotopes for a microscopic calculation.