New calculations of matter radii for neutron-rich C nuclei

We have used a simple model to re-calculate matter radii for ^14–20C, using updated information on the relevant nuclear structure. Agreement with experiment is improved, but some small differences remain.     

Processes following thermalization of positive particles in condensed matter

In previous discussions of the details of the processes which can lead to the formation of muonium, Mu, and positronium, Ps, the two fields of study have often been compared. In this communication we discuss the various mechanisms of Mu and Ps formation and particular attention is given to some of the more important differences between the physical properties of muons and positrons in condensed matter. Also, we discuss possible Mu and Ps reactions with some of the transient species created during the slowing down of the muon or positron. The effect of these latter processes may be that part of the formed Mu or Ps will not be recognized by the normal experimental techniquies. Furthermore, it is emphasized that the kinetics of the various muon and positron reactions are those of non-homogeous-kinetics.     

碰撞锁模环形染料激光器动力学过程的研究

本文在建立碰撞锁模(CPM)激光器数学模型的基础上,对碰撞锁模激光器中激光锁模脉冲形成的动力学过程进行了计算机模拟计算,并对其结果进行了理论分析和讨论,得到了脉冲宽度、脉冲波形及对称性与泵浦速率、腔长、增益介质和可饱和吸收介质在腔内的相对位置等因素间的关系。     

An effective pair potential for liquid semiconductor, Se: Structure and related dynamical properties

The effective pair potential of liquid semiconductor Se is extracted from its experimental structure factor data using an accurate liquid state theory and this shows important basic features. A model potential incorporating the basic features of the structure factor extracted potential is suggested. This model potential is then used to describe through low-order perturbation theory, the structure and related dynamical properties like self-diffusion coefficient and shear viscosity of this complex liquid over a wide range of temperatures.     

Wetting phase transitions and critical phenomena in condensed matter

Equilibrium wetting phase transitions and critical phenomena are discussed from a phenomenological point of view. The ubiquitous character of the wetting phase transition is illustrated through its occurrence in a variety of condensed matter systems, ranging from classical fluids to superconductors and Bose-Einstein condensates. The intriguing behaviour of the three-phase contact line and its line tension, at wetting, is an example of a fundamental problem in this field on which much progress has been made.     

Synchronization phenomena for a pair of locally coupled chaotic electrochemical oscillators: a survey

Chaotic synchronization of two locally coupled electrochemical oscillators is studied numerically. Both bidirectional and unidirectional couplings are considered. For both these coupling scenarios, varying the characteristics of the coupling terms (functional form and/or strength) reveals a wide variety of synchronization phenomena. Standard diagnostic tests are performed to verify and classify the different types of synchronizations observed.     

Suppression of band crossing in the neutron-rich nuclei 172, 173Yb due to the absence of a static pair field

High-spin states in the neutron-rich nuclei ^172,173Yb have been populated in a ¹⁷⁰Er(⁷Li,(p,d,t)xn) incomplete-fusion reaction and the emitted γ-radiation was detected with the GASP array. The signature partners of the 7/2⁺[633] rotational band of the odd-N ¹⁷³Yb isotope have been newly established and were observed up to spin values of (45/2⁺) and (43/2⁺), respectively. The ground-state band of the even-even nucleus ¹⁷²Yb has been observed up to a spin value of (22⁺). No band crossings were found in these bands. To explain this observation, it is proposed that the static pair field is absent, considering that the neutron odd-even mass differences reach for these nuclei very small values and that the band crossing is absent in cranked shell modell calculations without pairing. The results indicate, however, that strong dynamic correlations are still present.     

Atomic collapse,Lorentz boosts,Klein scattering,and other quantum-relativistic phenomena in graphene

Electrons in graphene, which behave as massless relativistic Dirac particles, provide a new perspective on the relation between condensed matter and high-energy physics. We discuss atomic collapse, a phenomenon in which discrete energy levels of superheavy atoms are transformed into resonant states. Charge impurities in graphene provide a convenient condensed matter system in which this effect can be explored. Relativistic dynamics also manifests itself in graphene p–n junctions. We show how the transport problem in the presence of a magnetic field can be solved with the help of a Lorentz transformation, and use it to investigate magnetotransport in p–n junctions. Finally, we review a recent proposal to use Fabry–Pérot resonances in p–n–p structures as a vehicle to investigate Klein scattering, another hallmark phenomenon of relativistic dynamics.     

Study of giant pairing vibrations with neutron-rich nuclei

We investigate the possible signature of the presence of giant pairing states at an excitation energy of about 10 MeV via two-particle transfer reactions induced by neutron-rich weakly bound projectiles. Performingparticle-particle RPA calculations on ²⁰⁸Pb and BCS + RPA calculations on ¹¹⁶Sn, we obtain the pairing strength distribution for two-particle addition and removal modes. Estimates of two-particle transfer cross sections can be obtained in the framework of the macroscopic model. The weak-binding nature of the projectile kinematically favors transitions to high-lying states. In the case of the (⁶He, ⁴He) reaction, we predict a population of the Giant Pairing Vibration with cross sections of the order of a millibarn, dominating over the mismatched transition to the ground state.     

Quantum chaos, thermalization and dissipation in nuclear systems

Nuclei have complex energy-level sequence with statistical properties in agreement with canonical random matrix theory. This agreement appears when the one-particle one-hole states are mixed completely with two-particle two-hole states. In the transition, there is a new universality which we present here, bringing about a relation between dynamics and statistics. We summarize also the role of chaos in thermalization and dissipation in isolated systems like nuclei. The methods used to bring forth this understanding emerge from random matrix theory, semiclassical physics, and the theory of dynamical systems.     

Haloes and clustering in light, neutron-rich nuclei

Clustering is a relatively widespread phenomenom which takes on many guises across the nuclear landscape. Selected topics concerning the study of halo systems and clustering in light, neutron-rich nuclei are discussed here through illustrative examples taken from the Be isotopic chain. The production and detection of multineutron clusters is also briefly presented. Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002 RID="a" ID="a"e-mail: orr@caelav.in2p3.fr     

Defining under and over-doping as bond order phenomena in the pair plaid model

Within the rules of a pair plaid model charge-lattice lock-in patterns are identified, which are responsible for the trends to characteristic hole values for a variety of features in the doping curves [onsets, kinks or optima,] of cuprates and related materials. Examples are the prevalence of optimal hole values of 0.16, 0.22 or 0.25. Selection of one of these values depends on the degree of isolation of the plane. Periods of pair plaid represent a central aspect for an algorithm of T_c or doping curve predictions when combined with the plane isolation model. Aspects of the theoretical concept of pair plaids have been made visible in recent STM graphs indicating electronic crystal behavior for the related pseudo-gap region. Pair plaids are in competition with stripes of non-superconducting singles and can be transformed into them. This competition is further elucidated with emphasis on the regions, where both orders can coexist. This further defines over and under-doping.     

A four-thirds law for phase randomization of stochastically perturbed oscillators and related phenomena

LetI be a set of invariants and be a set of angle variables for a system of differential equations with anO() vector field. When time dependent stochastic perturbations, also ofO(), are added to the system, we have shown that under suitable conditionsI becomes a stochastic adiabatic invariant satisfying a diffusion equation on time scales of order 1/², in the limit as »0. Here we show that the angle variables converge weakly to a Gaussian Markov process on an O(^-4/3) time scale, and thus the phase becomes randomized at these times. Application to nearly integrable Hamiltonian systems is considered.Supported by NSF grant DMR-8704348     

Atomic quantum diffusion,tunnelling states and some related phenomena in condensed systems

This article presents a review of some basic problems and results in the theory of atomic quantum diffusion, atomic tunnelling states and some related phenomena in condensed systems: crystals and amorphous materials.General concepts, including the defecton concept, are reviewed in the introduction. The first part of this paper considers the principal ideas, results and problems in the quantum diffusion theory for both underbarrier and overbarrier transitions of atomic particles in solids. Much attention is given to the fundamental role of the interactions between a weakly tunnelling particle and its environment, i.e. defects, other tunnelling particles and thermal fluctuations of atomic configurations.The second part of this review deals with the theory of atomic tunnelling states, their peculiar origin and low-temperature effects and, particularly, the origin and effects of the intrinsic atomic low-energy excitations in amorphous materials. The third part of this article discusses some related low-temperature phenomena. Some experimental data associated with the phenomena under consideration are presented. Finally, some actual problems of the theory are discussed in the Concluding Remarks.The review contains a discussion of results mainly coming to our attention by the summer of 1982.