Particle Physics

Abstract

A few years ago, when some of us were working to introduce particle physics into A-level courses, I exchanged letters with a professor of particle physics who expressed the view that we would not succeed in our aims, on the grounds that there were no textbooks that treated particle physics at an appropriate level. Our opinion at the time was that the professor had got his causality back to front, as history has indeed shown. The establishment of A-level particle physics options has prompted authors and publishers to produce several texts for sixth-formers, of which this is one. This book is a companion to Patrick Fullick's Physics in the Heinemann Advanced Science series, and it has the same general design features: full colour, many photographs, attractive layout, boxes containing detailed information and extension material, questions, summaries. These features make it more attractive than some of its rivals. It also covers the current syllabuses comprehensively, with chapters on High energy physics (i.e. accelerating particles), Detectors, Leptons, Antimatter, The nucleus, Hadrons and quarks, The forces of nature, Particle physics and cosmology, and Nuclear power. A short Introduction `In search of perfect symmetry' sets the tone for the rest of the book and illustrates what are, in my view, its main strengths and weaknesses. Following a discussion of reflection and rotation, there are accounts of Noether's Theorem (which shows that momentum and energy conservation arise from symmetry in the mathematical description of the universe), CPT invariance (illustrated with Feynman diagrams), and supersymmetry and superstrings. There are appeals to symmetry throughout the book, notably in a discussion of Dirac's prediction of antimatter. This is both a strength and a weakness. Symmetry offers insights not normally found in A-level work, but I suspect that the majority of sixth-form physicists will find it hard to engage with. The Feynman diagrams in the Introduction illustrate a recurrent problem, namely that some unfamiliar and quite difficult ideas are used before they are explained. Feynman diagrams are `done' in chapter 4; terms such as hadron and strong force are used in chapters 2 and 3 but not really explained until chapter 6. (In a variation on this theme, some ideas, e.g. energy-time uncertainty, are introduced from scratch in two different chapters.) Also, while there are boxes summarizing some key areas of physics (charged particles in electric and magnetic fields, for example), a lot of general A-level physics knowledge is assumed without comment (e.g. projection of vectors, frames of reference, the Planck equation). The book is thus most likely to be useful in a nuclear or particle physics option taught quite late in an A-level course, and would be best used for additional support and information after a topic has been introduced in class rather than for introductory reading. The inclusion of superstrings and supersymmetry illustrates another strength: the book is up to date. The discovery of the top quark is in, as are the scrapping of the American Superconducting Super Collider project and the development of the Large Hadron Collider at CERN, and the as yet undiscovered Higgs particle (but no WIMPs). Further strengths include a good discussion of forces (`one end of an interaction'), a nice summary of the ways matter and radiation can interact and a helpful explanation of why heavy nuclei are relatively neutron rich - to name but a few. This is, in summary, a worthwhile book, which should appeal particularly to students (and teachers) with a theoretical turn of mind. The professor should approve.