Foreword: Nuclear methods in magnetism

1998 ◽  
Vol 51 (2) ◽  
pp. 153
Keyword(s):  
Kondo Effect ◽  
Theoretical Work ◽  
Heavy Ion ◽  
Magnetic Behaviour ◽  
Special Importance ◽  
Electron Configuration ◽  
Distribution Method ◽  
Recoil Implantation ◽  
Recent Developments ◽  
Basic Features

Usually, the occurrence of magnetism on isolated, substitutional 3d, 4d and 5d impurity ions in metals is restricted to certain 3d ions (mainly Cr, Mn, Fe, Co, Ni) in alloying metallic systems. The application of the perturbed γ-ray distribution method following heavy ion reactions and recoil implantation has offered an experimental technique for producing and investigating new magnetic systems. Of special importance are nonalloying systems, which can exhibit extreme variations of e.g. density of states and atomic volume in the probe–host combinations produced by recoil implantation. Recent developments in this field include the following: Magnetism and the Kondo effect observed for 43Sc ions in alkali metal hosts are found to be consistent with a nearly localised, ionic 3d1 single-electron configuration, and parallel the behaviour observed in certain Ce systems. More generally, essential features of the magnetism of 3d and 4d ions in sp metal hosts are similar to those of 4f systems. Recent experimental and theoretical studies of 54Fe in d-band metal hosts are of key importance for an understanding of the basic features of local moment formation on substitutional Fe ions in transition metal hosts in general. In many nonalloying 54Fe probe-host combinations, (at least) two different magnetic responses have been detected. These components correspond to substitutional and interstitial sites of the implanted probes, as has been verified by in-beam Mössbauer spectroscopy of 57Fe in a series of host metals. This provides new insight into lattice site occupation as a function of host properties and allows directed investigations of the magnetic behaviour of Fe (and Mo) ions on interstitial lattice sites. Depending on the host metal, interstitial Fe is found to be nonmagnetic, e.g. in Zr, or magnetic, e.g. in Yb. Surprisingly, even the 4d ion Mo can be magnetic on interstitial sites. The experimental results for the substitutional as well as the interstitial sites can be compared to extensive theoretical work within the framework of local spin density calculations.

scholarly journals Magnetic Behaviour of Implanted Transition Metal Probes at Different Lattice Sites in Metals

1998 ◽  
Vol 51 (2) ◽  
pp. 157 ◽  
Author(s):  
D. Riegel ◽  
W. D. Brewer
Keyword(s):  
Transition Metal ◽  
Kondo Effect ◽  
Theoretical Work ◽  
Heavy Ion ◽  
Magnetic Behaviour ◽  
Special Importance ◽  
Electron Configuration ◽  
Distribution Method ◽  
Recoil Implantation ◽  
Basic Features

Usually, the occurrence of magnetism on isolated, substitutional 3d, 4d and 5d impurity ions in metals is restricted to certain 3d ions (mainly Cr, Mn, Fe, Co, Ni) in alloying metallic systems. The application of the perturbed γ-ray distribution method following heavy ion reactions and recoil implantation has offered an experimental technique for producing and investigating new magnetic systems. Of special importance are nonalloying systems, which can exhibit extreme variations of e.g. density of states and atomic volume in the probe–host combinations produced by recoil implantation. Recent developments in this field include the following: Magnetism and the Kondo effect observed for 43Sc ions in alkali metal hosts are found to be consistent with a nearly localised, ionic 3d1 single-electron configuration, and parallel the behaviour observed in certain Ce systems. More generally, essential features of the magnetism of 3d and 4d ions in sp metal hosts are similar to those of 4f systems. Recent experimental and theoretical studies of 54Fe in d-band metal hosts are of key importance for an understanding of the basic features of local moment formation on substitutional Fe ions in transition metal hosts in general. In many nonalloying 54Fe probe-host combinations, (at least) two different magnetic responses have been detected. These components correspond to substitutional and interstitial sites of the implanted probes, as has been verified by in-beam Mössbauer spectroscopy of 57Fe in a series of host metals. This provides new insight into lattice site occupation as a function of host properties and allows directed investigations of the magnetic behaviour of Fe (and Mo) ions on interstitial lattice sites. Depending on the host metal, interstitial Fe is found to be nonmagnetic, e.g. in Zr, or magnetic, e.g. in Yb. Surprisingly, even the 4d ion Mo can be magnetic on interstitial sites. The experimental results for the substitutional as well as the interstitial sites can be compared to extensive theoretical work within the framework of local spin density calculations.

scholarly journals The First Moment of Azimuthal Anisotropy in Nuclear Collisions from AGS to LHC Energies

2016 ◽  
Vol 2016 ◽  
pp. 1-16 ◽  
Author(s):  
Subhash Singha ◽  
Prashanth Shanmuganathan ◽  
Declan Keane
Keyword(s):  
Quark Gluon Plasma ◽  
Charged Particles ◽  
Theoretical Work ◽  
Heavy Ion ◽  
Gluon Plasma ◽  
Azimuthal Anisotropy ◽  
Flow Focusing ◽  
Nuclear Collisions ◽  
Ion Collisions ◽  
First Moment

We review topics related to the first moment of azimuthal anisotropy (v1), commonly known as directed flow, focusing on both charged particles and identified particles from heavy-ion collisions. Beam energies from the highest available, at the CERN LHC, down to projectile kinetic energies per nucleon of a few GeV per nucleon, as studied in experiments at the Brookhaven AGS, fall within our scope. We focus on experimental measurements and on theoretical work where direct comparisons with experiment have been emphasized. The physics addressed or potentially addressed by this review topic includes the study of Quark Gluon Plasma and, more generally, investigation of the Quantum Chromodynamics phase diagram and the equation of state describing the accessible phases.

scholarly journals QUANTUM GRAVITY BY THE COMPLEX CANONICAL FORMULATION

1992 ◽  
Vol 01 (03n04) ◽  
pp. 439-523 ◽  
Author(s):  
HIDEO KODAMA
Keyword(s):  
General Relativity ◽  
Quantum Gravity ◽  
Conventional Treatment ◽  
Quantum States ◽  
Hamiltonian Constraint ◽  
Canonical Formulation ◽  
Recent Developments ◽  
Canonical Approach ◽  
New Formulation ◽  
Basic Features

The basic features of the complex canonical formulation of general relativity and the recent developments in the quantum gravity program based on it are reviewed. The exposition is intended to be complementary to the review articles already available and some original arguments are included. In particular the conventional treatment of the Hamiltonian constraint and quantum states in the canonical approach to quantum gravity is criticized and a new formulation is proposed.

Electron cloud in accelerators

2014 ◽  
Vol 29 (17) ◽  
pp. 1430023 ◽  
Author(s):  
Roberto Cimino ◽  
Theo Demma
Keyword(s):  
Beam Quality ◽  
Theoretical Work ◽  
Mitigation Strategies ◽  
Cloud Formation ◽  
Predictive Capability ◽  
Physical Origin ◽  
Low Energy Electrons ◽  
Science Laboratories ◽  
Basic Features ◽  
Positively Charged

Low energy electrons in accelerators are known to interact with the circulating beam, giving rise to the formation of a so-called e- cloud. Such e- cloud may induce detrimental effects on the accelerated beam quality and stability. Those effects have been observed in most accelerators of positively charged particles. A longstanding effort has been so far devoted to understand in detail the physical origin of such e- cloud, its build-up and its interaction with the circulating beam. We will first describe the origin and the basic features causing e- cloud formation in accelerators, then we review some of the theoretical work produced to simulate and analyze such phenomenon. In selected cases, theoretical expectations and experimental observations will be compared, to address the importance of benchmarking codes versus observations to reach the required predictive capability. To this scope, codes need realistic input parameters which correctly describe material and surface properties at the basis of such e- cloud formation and build-up. The experimental efforts, performed worldwide in many surface and material science laboratories, to measure such essential parameters will then be presented and critically reviewed. Finally, we will describe some of the e- cloud mitigation strategies adopted so far and draw some conclusions.

scholarly journals Recent developments of ion sources for life-science studies at the Heavy Ion Medical Accelerator in Chiba (invited)

2016 ◽  
Vol 87 (2) ◽  
pp. 02C107 ◽  
Author(s):  
A. Kitagawa ◽  
A. G. Drentje ◽  
T. Fujita ◽  
M. Muramatsu ◽  
K. Fukushima ◽  
...  
Keyword(s):  
Life Science ◽  
Science Studies ◽  
Heavy Ion ◽  
Ion Sources ◽  
Recent Developments

scholarly journals Angular momentum transport in accretion disks: a hydrodynamical perspective

2019 ◽  
Vol 82 ◽  
pp. 391-413 ◽  
Author(s):  
S. Fromang ◽  
G. Lesur
Keyword(s):  
Angular Momentum ◽  
Accretion Disk ◽  
Accretion Disks ◽  
Dynamical Evolution ◽  
Theoretical Work ◽  
Momentum Transport ◽  
Angular Momentum Transport ◽  
Recent Developments ◽  
The Many ◽  
The Universe

The radial transport of angular momentum in accretion disk is a fundamental process in the universe. It governs the dynamical evolution of accretion disks and has implications for various issues ranging from the formation of planets to the growth of supermassive black holes. While the importance of magnetic fields for this problem has long been demonstrated, the existence of a source of transport solely hydrodynamical in nature has proven more difficult to establish and to quantify. In recent years, a combination of results coming from experiments, theoretical work and numerical simulations has dramatically improved our understanding of hydrodynamically mediated angular momentum transport in accretion disk. Here, based on these recent developments, we review the hydrodynamical processes that might contribute to transporting angular momentum radially in accretion disks and highlight the many questions that are still to be answered.

scholarly journals Recent developments in particle yield fluctuation measurements

2019 ◽  
Vol 204 ◽  
pp. 03003
Author(s):  
Igor Altsybeev
Keyword(s):  
Heavy Ion ◽  
Relativistic Heavy Ion Collisions ◽  
Initial State ◽  
Average Transverse Momentum ◽  
Correlation Studies ◽  
Ion Collisions ◽  
Particle Yield ◽  
Different Types ◽  
Recent Developments ◽  
Dynamical Fluctuations

In relativistic heavy-ion collisions, properties of the initial state and effects arising during evolution of the medium, such as a transition between the hadronic and partonic phases, should reflect themselves in event-by-event fluctuations of the number of produced particles. In this paper, recentmeasurements of several event-by-event observables, namely, dynamical fluctuations of relative particle yields and forwardbackward correlations of different types, are discussed. Also, new observables for forward-backward correlation studies are proposed: correlations between ratios of identified particle yields in two separated acceptance intervals and the correlation between the ratio in one interval and average transverse momentum in another.

scholarly journals Investigation on magne-crystallic action VI. Further studies on paramagnetic crystals

1939 ◽  
Vol 238 (788) ◽  
pp. 125-148 ◽  
Keyword(s):  
Single Crystals ◽  
Electric Fields ◽  
Low Temperatures ◽  
Theoretical Work ◽  
Magnetic Behaviour ◽  
Magnetic Studies ◽  
Angular Momenta ◽  
Recent Theoretical Work ◽  
Paramagnetic Ions ◽  
Van Vleck

In some of the earlier papers in this series (Part II, 1933; Part IV, 1936; Part V, 1938) we gave an account of magnetic studies on single crystals of several paramagnetic salts of the rare earth and the iron groups, and a discussion of the results on the basis of the recent theoretical work of Van Vleck (1932 a, b ), and Penney and Schlapp (1932), on the influence of the strong local electric fields acting on the paramagnetic ions in the crystals on their magnetic behaviour. Paramagnetic studies on single crystals are of interest because of the variety of information one can obtain from them under favourable conditions—on such widely different topics as the magnitude and the asymmetry of the electric field acting on the paramagnetic ion in the crystal; the geometry of distribution of the negatively charged atoms immediately surrounding the paramagnetic ion, and hence the co-ordination number of the ion; the strength of coupling between the orbital and the spin angular momenta of the electrons in the incomplete shell of the ion; and in those crystals in which the paramagnetic ions are all in the S-state, the magnitude of the Stark separation of the S-levels, which plays an important part in determining the thermal properties of the crystal at very low temperatures ( = 0T °K ); etc. Several examples were given, in the papers referred to, to illustrate these various aspects of the magnetic studies on paramagnetic crystals.

Approaches to Residential Location Modelling 2: Urban Economic Models and Some Recent Developments (A Review)

1974 ◽  
Vol 6 (4) ◽  
pp. 369-409 ◽  
Author(s):  
M L Senior
Keyword(s):  
Predictive Models ◽  
Critical Appraisal ◽  
Spatial Interaction ◽  
Theoretical Work ◽  
Recent Model ◽  
Economic Theories ◽  
Spatial Interaction Models ◽  
Urban Economic ◽  
Recent Developments ◽  
Operational Models

This is the second half of a two part paper reviewing models of the residential subsystem. Part 1 (Senior, 1973)(1) covered urban ecological and spatial interaction models, and concluded on the theme that improved operational predictive models may result from an increased awareness of theoretical work. The theme is continued here with a critical appraisal of economic theories of the housing market and the operational models that urban economists have devised. This provides the basis for a wider ranging review of the ties between existing theories and some recent model developments.

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