6 June 2011

Induction Accelerators
By Ken Takayama and Richard Briggs (eds.)
Hardback: €126.55 £108 $169

Of the nearly 30,000 particle accelerators now operating worldwide, few types are as unfamiliar to most physicists and engineers as induction accelerators. This class of machine is likewise poorly represented in technical monographs. Induction Accelerators, a volume of 12 essays by well known experts, forms a structured exposition of the basic principles and functions of major technical systems of induction accelerators. The editors have arranged the essays in the logical progression of chapters in a textbook. Nonetheless, each has been written to be useful as a stand-alone text.

Apart from the two chapters about induction synchrotrons, the book is very much the product of the “Livermore/Berkeley school” of technology of induction linear accelerators (linacs) started by Nicholas Christofilos and led for many years by Richard Briggs as the Beam Research Program at the Lawrence Livermore National Laboratory. The chapters by Briggs and his colleagues John Barnard, Louis Reginato and Glen Westenskow are masterful expositions marked by the clarity of analysis and physics motivation that have been the hallmarks of the Livermore/Berkeley school. A prime example is the presentation of the principles of induction accelerators that, despite its brevity, forms an indispensable introduction by the master in the field to a discussion (together with Reginato) of the many trade-offs in designing induction cells.

One application of induction technology made important by affordable, solid-state power electronics and high-quality, amorphous magnetic materials is the induction-based modulator. This application grew from early investigations of magnetic switching by Daniel Birx and his collaborators; it is well described by Edward G Cook and Eiki Hotta in the context of a more general discussion of high-power switches and power-compression techniques.

Invented as low-impedance, multistage accelerators of high-current electron beams, induction machines have always had the central challenge of controlling beam instabilities and other maladies that can spoil the quality of the beam. Such issues have been the focus of the major scientific contribution of George Caporaso and Yu-Jiuan Chen, who – in the most mathematical chapter of the book – discuss beam dynamics, the control of beam break-up instability and the suppression of emittance growth resulting from the combination of misalignment and chromatic effects in the beam transport.

In ion induction linacs proposed for use as inertial-fusion energy drivers, an additional class of instabilities is possible, namely, unstable longitudinal space–charge waves. These instabilities are analysed in a chapter by Barnard and Kazuhiko Horioka titled “Ion Induction Linacs”. It is followed by a description of the applications of ion linacs, especially to heavy-ion-driven inertial fusion and high-energy density research. These chapters contain the most extensive bibliographies of the book.

The use of induction devices in a synchrotron configuration was studied at Livermore and at Pulsed Sciences Inc in the late 1980s. However, it was not until the proof-of-concept experiment by Takayama and his colleagues at KEK, who separated the functions of acceleration and longitudinal focusing, that applications of induction accelerators to producing long bunches (super-bunches) in relativistic-ion accelerators became a possibility for an eventual very large hadron collider. These devices and their potential applications are described in the final chapters of the book.

Both physicists and engineers will find the papers in Induction Accelerators well written with ample – though not exhaustive – bibliographies. While the volume is not a textbook, it could profitably be used as associated reading in a course about accelerator science and technology. Induction Accelerators fills a void in the formal literature on accelerators. It is a tribute to Nicholas Christofilos and Daniel Birx, the two brilliant technical physicists, to whom this volume is dedicated. I recommend it highly.

William Barletta, director of the US Particle Accelerator School and adjunct professor of physics at MIT and UCLA.

Exploring Fundamental Particles
By Lincoln Wolfenstein and João P Silva
Taylor & Francis; CRC Press 2011
Paperback: £30 $49.95
E-book: $49.95

Writing a book is no easy task. It surely requires a considerable investment of time and effort (it is difficult enough to write short book reviews). This is especially true with books about complex scientific topics, written by people who are certainly not professional writers. I doubt that the authors of the books reviewed in the CERN Courier have taken courses on how to write bestsellers. Being such hard work, the authors must have good reasons to embark on the daunting challenge of writing a book.

When I started reading Exploring Fundamental Particles, I immediately wondered what could have been the reasons that triggered Lincoln Wolfenstein and João Silva to write such a book. After all, there are already many “textbooks” about particle physics, both in generic terms and in specific topics. For instance, the puzzling topic of CP violation is described in much detail in the book CP Violation (OUP 1999), by Gustavo Branco, Luís Lavoura and João Silva (the same João Silva, despite the fact that João and Silva are probably the two most common Portuguese names). There are also many books about particle physics that address the “general public”, such as the fascinating Zeptospace Odyssey (OUP 2009), by Gian Giudice (CERN Courier April 2010 p40), which is a nice option for summer reading, despite the somewhat weird title (the start-of-section quotations are particularly enjoyable).

Exploring Fundamental Particles follows an intermediate path. It addresses a broad spectrum of physics topics all of the way from Newton (!) and basic quantum mechanics to the searches for the Higgs boson at the LHC – building the Standard Model along the way. And yet, despite its wide scope, the book focuses with particularly high resolution on a few specific issues, such as CP violation and neutrino physics, which are not exactly the easiest things to explain to a wide audience. The authors must have faced difficult moments during the writing and editing phases, trying hard to keep the text readable for non-experts, while giving the book a “professional touch”.

This somewhat schizophrenic style can be illustrated by the fact that while the book is submerged in Feynman diagrams, some of them are quite hard to digest (“Penguins” and other beasts), it has no equations at all (not even the ubiquitous E=mc2) – maybe for fear of losing the reader – until we reach the end of the book (the fifth appendix, after more than 250 pages, where we do see E=mc2). The reading is not easy (definitely not a “summertime book”) so, for an audience of university students and young researchers, adding a few equations would have improved the clarity of the exposition.

I also found it disturbing to see the intriguing discussions of puzzling subjects interrupted by trivial explanations on how to pronounce “Delta rho”, “psi prime” etc. These parenthetical moments distract the readers who are trying to remain concentrated on the important narrative and are useless to the other readers. (If you do not know how to pronounce a few common Greek letters, you are not likely to survive a guided tour through the CKM matrix.)

I hope the authors (and editor) will soon revise the book and publish a second edition. In the meantime, I will surely read again a few sections of this edition; for certain things, it is really quite a useful book.

Carlos Lourenço, CERN.

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