arXiv subjects

W. Dong

Publications and source records attributed to W. Dong.

7 recordsLinked to original sources

arXiv2026

A prototype gas cell for the stopping, extraction and neutralization of radioactive nuclei from the SPIRAL2 Super Separator Spectrometer (S$^3$)

We present the design and simulation of a prototype gas cell for in-gas-jet laser-ionization and spectroscopy studies using the low energy branch of the SPIRAL2-S$^3$ radioactive-ion-beam facility. The prototype aims to demonstrate the possibility to reduce the extraction time of radioactive ions from the gas cell, while implementing a controlled neutralization mechanism, necessary for laser-spectroscopy studies. Different simulation methods of ion processes in gas are comparatively discussed. Design considerations and detailed simulations of the ion extraction time and efficiency are presented. A study of the dynamics of electrons obtained in the gas cell by ionization is also performed to assess the achievable electron densities.

physics.ins-det↗

arXiv2025

An experimental setup for the study of gas-cell processes for the S$^3$-Low Energy Branch

We present an experimental setup dedicated to the study of in-gas ion processes and characterization of gas stopping cells for the Low Energy Branch of the Super Separator Spectrometer (S$^3$) at SPIRAL2-GANIL. The first application is the development of a new gas stopper with a neutralization mechanism designed for faster extraction of the radioactive ions. This development should enable in-gas-jet laser spectroscopy and other low-energy experiments with shorter lived radioactive isotopes. We discuss in detail the motivation and objectives of these developments and we present the results of simulations performed in the design phase, as well as the first experimental results.

physics.ins-det↗

arXiv2025

Incompatibility of rank-one POVMs and quantum uncertainty relations

The incompatibility of quantum measurements is a fundamental feature of quantum mechanics with profound implications for uncertainty relations and quantum information processing. In this paper, we extend the notion of {\em $s$-order incompatibility} of measurements, introduced by Xu (inspired by De Bi\`evre's ``complete incompatibility" ), to more general rank-one POVMs, and establish novel uncertainty relations. Furthermore, we investigate the incompatibility of multiple POVMs and its connection to support uncertainty relations. These results may have applications in quantum cryptography, quantum state reconstruction, and quantum compressed sensing.

quant-ph↗

arXiv2017

Model charged cylindrical nanopore in a colloidal dispersion: charge reversal, overcharging and double overcharging

Using the hypernetted-chain/mean spherical approximation (HNC/MSA) integral equations we study the electrical double layer inside and outside a model charged cylindrical vesicle (nanopore) immersed into a primitive model macroions solution, so that the macroions are only present outside the nanopore, i.e., the vesicle wall is impermeable only to the external macroions. We calculate the ionic and local linear charge density profiles inside and outside the vesicle, and find that the correlation between the inside and outside ionic distributions causes the phenomena of overcharging (also referred to as surface charge amplification) and/or charge reversal. This is the first time overcharging is predicted in an electrical double layer of cylindrical geometry. We also report the new phenomenon of double overcharging. The present results can be of consequence for relevant systems in physical-chemistry, energy storage and biology, e.g., nanofilters, capacitors and cell membranes.

cond-mat.mes-hall↗

arXiv2013

Phase behavior under the averaging over disorder realizations

Effects of the averaging over disorder realizations (samples) on the phase behavior are analyzed in terms of the mean field approximation for the random field Ising model with infinite range interactions. It is found that the averaging is equivalent to a drastic modification in the statistics of the quenched variables. In its turn, this lowers the critical temperature of a second-order phase transition or, depending on the sampling, even suppresses the ordered phase. Possible first order transitions are shown to be softened by the sample averaging. Common issues and differences in the interpretation of these effects in the context of the simulation and experimental studies are discussed.

cond-mat.stat-mech↗

arXiv2012

One-dimensional hard rod fluid in a disordered porous medium: scaled particle theory

The scaled particle theory is applied to a description of thermodynamic properties of one-dimensional hard rod fluid in disordered porous media. To this end, we extended the SPT2 approach, which had been developed previously. Analytical expressions are obtained for the chemical potential and pressure of a hard-rod fluid in hard rod and overlapping hard rod matrices. A series of new approximations for SPT2 are proposed. It is shown that apart from two well known porosities such as geometrical porosity and specific probe particle porosity, a new type of porosity defined by the maximum value of packing fraction of fluid particles in porous medium should be taken into account. The grand canonical Monte-Carlo simulations are performed to verify the accuracy of the SPT2 approach in combination with the new approximations. It is observed that the theoretical description proposed in this study essentially improves the results up to the highest values of fluid densities.

cond-mat.soft↗

arXiv2005

On the double criticality of fluids adsorbed in disordered porous media

The phase transition of a fluid adsorbed in a heterogeneous system is studied with two simple lattice gas models within the framework of a mean-field theory. Despite the different origin of the heterogeneity (spatial variation of binding energy or fluid coordination numbers), the fluid can undergo two phase transitions if the hosting system is sufficiently heterogeneous. It is clearly shown that such a polymorphism in the confined fluid results from the successive condensations in distinct spatial regions of the host. We have found the precise conditions at which one two phase transitions occur. The insight gained from the present study allows one to understand better some recent puzzling simulation results.

cond-mat.stat-mech↗