Particle Accelerators: from Big Bang Physics to Hadron Therapy

Particle Accelerators: From Big Bang Physics to Hadron Therapy Ugo Amaldi Particle Accelerators: From Big Bang Physics to Hadron Therapy ThiS is a FM Blank Page Ugo Amaldi Particle Accelerators: From Big Bang Physics to Hadron Therapy With the Collaboration of Adele La Rana Translated by Geoffrey Hall Ugo Amaldi CERN Europ. Organization for Nuclear Research Geneva 23 Switzerland The translation of this work has been funded by SEPS SEGRETARIATO EUROPEO PER LE PUBBLICAZIONI SCIENTIFICHE, Via Val d’Aposa 7, 40123 Bologna, Italy; e-mail: [email protected]; www.seps.it. Translation from the Italian language edition of: Sempre piu` veloci, Copyright © 2012 Zanichelli editore S.p.A., Bologna [6331]. Authorized translation from Italian language edition published by Zanichelli. All Rights Reserved. ISBN 978-3-319-08869-3 ISBN 978-3-319-08870-9 (eBook) DOI 10.1007/978-3-319-08870-9 Springer Cham Heidelberg New York Dordrecht London Library of Congress Control Number: 2014955693 © Springer International Publishing Switzerland 2015 This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmission or information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilar methodology now known or hereafter developed. Exempted from this legal reservation are brief excerpts in connection with reviews or scholarly analysis or material supplied specifically for the purpose of being entered and executed on a computer system, for exclusive use by the purchaser of the work. Duplication of this publication or parts thereof is permitted only under the provisions of the Copyright Law of the Publisher’s location, in its current version, and permission for use must always be obtained from Springer. Permissions for use may be obtained through RightsLink at the Copyright Clearance Center. Violations are liable to prosecution under the respective Copyright Law. The use of general descriptive names, registered names, trademarks, service marks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. While the advice and information in this book are believed to be true and accurate at the date of publication, neither the authors nor the editors nor the publisher can accept any legal responsibility for any errors or omissions that may be made. The publisher makes no warranty, express or implied, with respect to the material contained herein. Cover figure: Three images showing the three aspects of particle accelerators discussed in the book: machines, particle physics and medical applications. Credits: 1) Digital painting, “In search of the Higgs boson: H -> ZZ”: Xavier Cortada (with the participation of physicist Pete Markowitz), digital art, 2013; 2) Artistic view of LHC (Geneva): © CERN; 3) Proton treatment room at the Massachusetts General Hospital Francis H. Burr Proton Beam Treatment Center (Boston, USA): Courtesy IBA Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com) To Clelia ThiS is a FM Blank Page Preface The idea for this book grew gradually over time, taking shape from a long-standing enthusiasm for particle accelerators which originated when I took my first steps in the world of research. How to approach this theme became clear to me when, many years ago, I read what had been written by “Viki” Weisskopf, Director General of CERN from 1961 to 1965: “There are three kinds of physicists, namely the machine builders, the experimental physicists, and the theoretical physicists. The machine builders are the most important ones, because if they were not there, we would not get into this small-scale region of space. If we compare this with the discovery of America, the machine builders correspond to captains and ship builders who really developed the techniques at that time. The experimentalists were those fellows on the ships who sailed to the other side of the world and then landed on the new islands and wrote down what they saw. The theoretical physicists are those who stayed behind in Madrid and told Columbus that he was going to land in India.” The scientific adventures and discoveries I recount in this book have thus as main characters the machine builders, neglected heroes of the history of physics who rarely appear in the many excellent books on particle physics and cosmology published so far. During my career, I carried out experiments in fundamental physics at six different particle accelerators (two in Italy and four at CERN), and I have also published many papers dedicated to this type of instruments and have taught the subject in university courses as well. I have had the great good fortune to meet, and in some cases to work side by side with, several among those persons who laid the foundation of these extraordinary machines, which are capable of breaking down matter into its fundamental constituents but also serve as an invaluable means of diagnosis and treatment of cancer. This double aspect of instruments, at the service of knowledge on the one hand and in the service of health on the other, renders them a perfect example of how pure science and applied science are intimately interre- lated and indivisible. The first edition of this book was published as a pocket-sized paperback in Italy in October 2012. The following year, it took second place in the National Prize for vii viii Preface Scientific Communication awarded by the Italian Book Association, an event which encouraged me to expand the content for a successor edition, including material and personalities which I had to regretfully omit from the first. The result is that the English version has grown to become a volume twice the size of the Italian one, with many more figures and citations. For both editions, the collaboration of Adele La Rana, physicist and scientific writer, has been invaluable; she provided attentive and critical rereading and innumerable suggestions for much improved explanatory clarity and took responsibility for the search for artwork and the various editorial phases. The English edition has been much enhanced by the sensitive translation of Geoffrey Hall, who not only rendered with clarity the spirit of the text but also contributed – with helpful criticisms and suggestions – to correct errors and inaccuracies and to make the text more comprehensible. My gratitude is also extended to Alvaro De Rujula, Frank Close and Gino Segre`, who as scientists and communicators have provided me with important external perspectives; to Marco Durante, Michael Goitein and Gerhard Kraft, for their accurate and valuable criticisms of the chapters dedicated to accelerators for medical applications; to Guido Altarelli, Giorgio Brianti, Roberto Orecchia and Sandro Rossi, for the careful readings and suggestions; and to Federico Tibone, former editor of the series in which the Italian edition was included, who contributed with corrections and advice to the later improvement of the English version. I am particularly thankful to Ramon Khanna, my editor at Springer, who believed in the project from the outset and who provided many suggestions and has been patient with me during my many delays. Finally, I would like to thank Paolo Magagnin, for having helped me produce several complex, previously unpublished figures included in this book, and Daniele Bergesio, who lent his enthusiasm for photography to depict the CERN locations cited at the start of each chapter. Geneva, Switzerland Ugo Amaldi Prologue The athletes who participate in the Olympic Games run and swim ever faster, even if, with the passing of time, it becomes ever more challenging to beat former records. The same can be said of the particles that travel at (almost!) the speed of light in accelerators, those microscopes of the infinitely small. Everyone under- stands the motivations of athletes and Olympic organisers; physicists’ reasons are instead much less clear to non-experts. The question “why accelerate particles?” has become even more frequent since – in July 2012 – physicists from the Large Hadron Collider (or LHC) at the CERN laboratory near Geneva announced the discovery of the Higgs boson. It is a question which I will try to answer in this book, beginning with the history of a few important physical discoveries and some of the main characters involved. As we will see, it is a story in which research on fundamental aspects of nature – from the structure of matter to the origin of the universe – is interwoven with applications of great practical value, in particular for diagnosis and treatment of our illnesses. Subatomic Microscopes, Particle Factories The important development of particle accelerators, devices that usually have a circular shape, began about 80 years ago. Initially, for some decades, they were used to study the structure of matter: fast particles, once accelerated, were directed onto a target, for example a small piece of metal. Observing the products of the collisions provided information on the structure of atomic nuclei in the bombarded material. It was rather like exploring the contents of a darkened room by throwing a lot of marbles into it and observing the rebounds. Subsequently, the attention of physicists turned to the new particles produced in the collision between a fast particle and an atomic nucleus. Energy can be transformed into mass, as predicted by the relationship E ¼ mc2 discovered by ix x Prologue Einstein, and the energy released in collisions frequently gave rise to the creation of new particles. Most of these particles are ‘unstable’ in the sense that they live very briefly and then give rise to two, three, four..

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