Preface

Abstract

The papers in this special issue were presented at a three-day international symposium on `The Electronic and Defect Structure of Materials' held at the University of East Anglia, UK, on 26-28 March 1998. The occasion marked the sixtieth birthday of Professor Roy West, and was a celebration of Roy's many outstanding contributions to condensed matter physics. Many of the papers presented at the meeting were by Roy's present and former colleagues and by students, `grand-students' and by those whose work has been influenced by his contributions. Roy West gained his PhD at Birkbeck College under the supervision of Norman Cusack. Both moved to the University of East Anglia (UEA) where Roy was involved in experimental studies of electronic structure and positron states in metals and alloys using angular correlation and lifetime spectroscopies. In these early days Roy made pioneering contributions to his chosen field, for example the formulation in 1969 of the two-state trapping model - a cornerstone for the interpretation of positron-based defect studies. Roy is the `W' in the LCW theorem, which allows the transformation of the momentum density obtained by angular correlation (or Compton scattering) measurements into the projections of the occupation number n(k) in k space. The theorem has been widely applied since its publication (1973 J. Phys. F: Met. Phys. 3 561). It was especially pleasing to see Roy's students Dennis Lock and Vic Crisp (`L' and `C') at the symposium. Roy's authoritative book Positron Studies of Condensed Matter, published in 1974, has become a `bible' for several generations of graduate students entering the field, and is still quoted regularly in research papers. In the late 1970s Roy developed the use of medical gamma (Anger) cameras in two-dimensional angular correlation studies of Fermi surfaces in metals and alloys. An imaginative step forward at the time, typical of Roy's lateral but practical thinking, this approach is used widely to this day. In the 1980s Roy's interests broadened to include slow positron beams and their applications to surface and near-surface phenomena. He became a member of the positron consortium at Brookhaven National Laboratory, where the installation of two Anger cameras at either side of the intense positron beam line led to a number of important papers on surface electronic structure. In this same period Roy became Head of the School of Physics at UEA, approaching his administrative duties with the same zeal and fervour which have always been a feature of his scientific life. In 1987 Roy crossed the Atlantic to become Head of the Physics Department at the University of Texas at Arlington. There he continued his work on electronic structure and performed influential work on the fermiology of high-Tc materials. He continues to play a leading role in the field of electronic structure, contributing to the development of new and powerful data reduction techniques. Roy has always been a prominent member of the scientific community. He is justly proud to have contributed to every International Positron Annihilation Conference since the first in Detroit in 1965, and he serves on the International Committee for these triennial meetings. Roy's indomitable character is well known among all those who have known him, and his adventurous spirit has characterized all aspects of his life. At the symposium dinner it was a pleasure to hear Norman Cusack tell of Roy's tricycling prowess (a national record-holder, no less) in the days before he became a graduate student. Roy is still cycling, and still contributing in his lively, often colourful, way to condensed matter physics. Long may he continue to do so. The symposium also celebrated the sixtieth birthday of Professor Nobuhiro Shiotani, Tokyo University of Fisheries. Nobu has been one of the most significant contributors to the study of electronic structure in metallic systems using Compton scattering and positron annihilation. In recent years he has been one of the pioneers of synchrotron radiation based high resolution Compton scattering. M Ashraf Alam (University of Bristol) Paul G Coleman (University of East Anglia) Guest Editors