Exploring the Large Hadron Collider - The Discovery of the Higgs Particle : The World Machine Clearly Explained. PDF
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Michael Hauschild Exploring the Large Hadron Collider–The Discovery of the Higgs Particle The World Machine Clearly Explained essentials Springer essentials Springer essentials provide up-to-date knowledge in a concentrated form. They aim to deliver the essence of what counts as “state-of-the-art” in the current aca- demic discussion or in practice. With their quick, uncomplicated and comprehen- sible information, essentials provide: • an introduction to a current issue within your field of expertise • an introduction to a new topic of interest • an insight, in order to be able to join in the discussion on a particular topic Available in electronic and printed format, the books present expert knowledge from Springer specialist authors in a compact form. They are particularly suitable for use as eBooks on tablet PCs, eBook readers and smartphones. Springer essen- tials form modules of knowledge from the areas economics, social sciences and humanities, technology and natural sciences, as well as from medicine, psychol- ogy and health professions, written by renowned Springer-authors across many disciplines. More information about this subseries at https://link.springer.com/bookseries/16761 Michael Hauschild Exploring the Large Hadron Collider—The Discovery of the Higgs Particle The World Machine Clearly Explained Michael Hauschild Physics Department, CERN Geneva, Switzerland ISSN 2197-6708 ISSN 2197-6716 (electronic) essentials ISSN 2731-3107 ISSN 2731-3115 (electronic) Springer essentials ISBN 978-3-658-34382-8 ISBN 978-3-658-34383-5 (eBook) https://doi.org/10.1007/978-3-658-34383-5 This book is a translation of the original German edition „Neustart des LHC: die Entdeckung des Higgs-Teilchens“ by Hauschild, Michael, published by Springer Fachmedien Wiesbaden GmbH in 2018. The translation was done with the help of artificial intelligence (machine translation by the service DeepL.com). A subsequent human revision was done primarily in terms of con- tent, so that the book will read stylistically differently from a conventional translation. Springer Nature works continuously to further the development of tools for the production of books and on the related technologies to support the authors. © Springer Fachmedien Wiesbaden GmbH, part of Springer Nature 2021 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 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. 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The registered company address is: Abraham-Lincoln-Str. 46, 65189 Wiesbaden, Germany What You Can Find in This essential • Mass does it!—How the particles get their mass • From UFOs and more!—The LHC goes into the next round • The plan of the century!—Higgs, what next? v Preface The world machine, the Large Hadron Collider (LHC) at CERN, the European Organization for Nuclear Research near Geneva, is the largest particle accelerator in the world. The first ideas and concepts for the LHC were already made in the early 1980s. From these beginnings, however, it took more than a quarter of a century until the LHC was finally completed, a ring-shaped particle accelerator with a circumference of 27 km, 100 m below ground. When particle beams circu- lated in the LHC for the first time on September 10, 2008, the excitement among scientists was boundless. The launch of the LHC with live transmission from the LHC control room was in the top news media worldwide. The physicists were in each other’s arms. Only a few days later, on September 19, 2008, the big disillusionment came: during a test, one of over 10,000 cable connections could not withstand the high electric current and melted. No one was hurt, but the LHC was massively dam- aged and it took more than a year until it was finally possible to resume opera- tions in November 2009. In the accident investigations, the cable connections turned out to be a poten- tial weak point. It would have taken far more than a year to check and repair or even renew all the connections, so CERN management decided to run the LHC at half power for the time being to avoid overloading the connections. But even half the energy was enough to announce the discovery of a new ele- mentary particle on July 4, 2012 with the two large particle detectors ATLAS and CMS. And the LHC continued to run. In March 2013, the physicists from ATLAS and CMS were finally certain that the newly discovered particle was indeed the long-sought Higgs particle. More than 50 years ago, in 1964, theoretical physicists Robert Brout, François Englert, and Peter Higgs, among others, published ideas on how elementary vii viii Preface particles can acquire mass, that is, become heavy, and one consequence of their theories is the existence of a new particle, the Higgs particle, named after Peter Higgs. This particle was searched for at various particle accelerators and detec- tors around the world until the physicists finally found it at the LHC. Brout had already died in 2011 and could not live to see the triumph, but Englert and Higgs were awarded the Nobel Prize in Physics in autumn 2013 with great jubilation and the sympathy of the physicists involved at CERN. But this is not the end of research at the LHC, it is only the beginning. The newly discovered Higgs particle must be measured, its properties determined and compared with the theoretical predictions. Other new particles may be waiting to be found in the next few years, and each newly discovered particle could trigger a revolution in our understanding of the world and the universe. In 2013 and 2014, the LHC and the particle detectors have been made fit for the new challenges. The 2-year break was used to eliminate all weak points in the cable connections, install new security systems and improve the detectors in order to discover even more of nature’s secrets with higher energy. As more than 6 years earlier, the first circulating particle beams were eagerly awaited in March 2015 when the LHC was put back into operation. Two months later, on June 3, 2015, the first collisions took place with almost twice the energy as before: 13 TeV, comparable to the energy of two colliding mosquitoes, but highly concentrated on two tiny particles, and once again a new world record. The world machine is running again! In the coming years, particle physicists will look more intensively than ever before into their collected data from count- less collisions to see if there are any indications of new particles and new phe- nomena beyond the so-called Standard Model. This essential is part of a series on the restart of the LHC in spring 2015. You will follow how the initially bumpy start of the LHC was followed by the discov- ery of a new particle, the long-sought Higgs boson. The restart at higher energy and the prospects for future projects conclude this essential. In other essentials of this series you will learn more about the beginnings of CERN, one of the most fascinating research centers of all, its history, its people, and its accelerators. You will learn about the operation of particle accelerators and how the first ideas were used to build the LHC, today’s world machine. You will learn about the experiments at the LHC, how particle detectors work, the theory behind the Higgs and the Standard Model, and the theoretical approaches beyond the Standard Model. Michael Hauschild CERN, Geneva Contents 1 The Discovery of a New Particle .............................. 1 1.1 The Origin of Mass—The Field and the Particle ................ 2 1.2 Higgs Hunting—Before the LHC ........................... 4 1.3 Statistics is Everything .................................... 7 1.4 Is it a Higgs? ............................................ 10 1.5 The Nobel Prize ......................................... 16 2 The Restart ................................................ 19 2.1 A Long Stop ............................................ 19 2.2 The First Beam .......................................... 21 2.3 UFOs in the LHC ........................................ 22 2.4 A New World Record ..................................... 23 3 The Plan of the Century ...................................... 27 3.1 LHC, the Second ........................................ 27 3.2 Bigger, Faster, Further—Future Projects ...................... 29 4 Outlook .................................................... 33 References .................................................... 37 ix The Discovery of a New Particle 1 In the late 1950s and even more so in the early 1960s, new particles were discov- ered almost monthly. This was the birth of the Standard Model of particle phys- ics, which, like the periodic table of the chemical elements, brought order to the particle zoo, which had previously been growing in number. The Standard Model made it possible to trace the diversity of particles back to only a few elementary particles, which, like the chemical elements, could form the most diverse bonds and combinations. This also raised the question of how the mass of the elemen- tary particles came about. Although all the elementary particles in the Standard Model could be described excellently in theory, they were initially all massless in theory. A yet unknown additional mechanism had to take care of for their mass. As is so often the case in the sciences, there were several theoretical physicists who came up with a solution to the mass problem almost simultaneously and inde- pendently of each other, and who in turn built on preliminary work by others. In 1960, the Japanese Yoichiro Nambu (1921–2015) was actually working on a com- pletely different branch of physics, superconductivity, but in doing so he discov- ered a phenomenon that would eventually become decisive for particle physics. Solid-state bodies usually have a very regular structure: the atoms are arranged in a crystal lattice and exhibit certain symmetries, which manifest themselves particularly beautifully in snow crystals and countless crystal shapes and types, much sought after by collectors. Under certain circumstances, however, the inter- nal symmetry is disturbed, for example, when the tiny elementary magnets in a piece of iron are uniformly aligned by an external magnetic field. The formation of a preferred direction by the magnetic field causes a so-called spontaneous sym- metry breaking. Nambu and, 2 years later, the British theorist Jeffrey Goldstone were able to show that waves are created in the iron as a result of small oscillations of the elementary magnets. And since in the microscopic quantum world waves © Springer Fachmedien Wiesbaden GmbH, part of Springer Nature 2021 1 M. Hauschild, Exploring the Large Hadron Collider—The Discovery of the Higgs Particle, essentials, https://doi.org/10.1007/978-3-658-34383-5_1
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