Inelastic neutron scattering is a well established and important technique for studying the dynamical properties of condensed matter at the atomic level. Often, as is the case of experiments designed to study motions of hydrogen atoms, or magnetic excitations, it may yield information obtainable in no other way. Our aim in assembling this book is to produce an overview of some research topics which have come to the fore recently with the development of high neutron fluxes and high performance inelastic scattering spectrometers. The topics dis cussed here are, by and large, developing rapidly and have not reached the stage at which definitive accounts are always possible. Authors have not therefore attempted to make an extensive review of their topic, and the papers quoted in the text are, in general, those which are seen as having been important in its develop ment (they date, roughly, from the 1971 IAEA conference on neutron scattering held in Grenoble). Basic phenomena are illustrated for the most part by the discussion of one, or two, typical examples. The authors hope that the book will be useful to researchers who are not yet fully aware of the diverse range of problems to which the technique can be applied, and to students beginning research work. For this reason, the first chapter by S. w.

An international workshop on Elementary Excitations and Fluctuations in Magnetic Systems was held in San Miniato, Italy, for five days beginning 28 May, 1984. The workshop comprised eight working sessions that contai- ned a total of 43 invited talks, and 58 scientists were in attendance from 14 countries. Our aim was to review some topics of current interest in the statistical physics of magnetic materials and models, with an emphasis on theoretical studies and confrontations between these and experimental and computer simulation data. book contains summary papers written by the invited speakers, and This the material will be of immediate interest to graduate students and resear- chers engaged in studies of magnetic properties. There is, perhaps, no ef- fective way to record and convey the benefit of the numerous discussions between the participants that are a significant integral feature of a work- shop. The magnificent .venue of the workshop, I Cappuccini, was made availa- ble to us by the.Cassa di Risparmio San Miniato. Financial support for the workshop was received from Consiglio Nazionale delle Ricerche, Universita degli Studi di Firenze and the Gruppo Nazionale Struttura,della Materia. Our administrative load and the burden of preparing the proceedings for publication was made light by the talents of Carla Pardini (CNR, Florence), and Caroline Monypenny and Jane Warren (Rutherford Appleton Laboratory). Fina 11y, we wish to thank all the participants for their attendance and individual contributions to the success of the workshop.

This is the first book devoted to the use of X-ray beam techniques to study magnetic properties of materials. It covers both experimental and theoretical issues. The three main topics are dichroism, elastic scattering (both non-resonant and resonant diffraction) and spectroscopy. In the past decade there has been an expansion of activity in the field, driven by the availability of intense, tuneable and highly polarized X-ray beams from synchrtron facilities. The pace of events is likely to continue with the start of new (3rd generation) facilities, including the European Synchrotron Radiation Facility, Grenoble, and the Advanced Light Source, Argonne National Laboratory. USA.