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Trapped Charged Particles: A Graduate Textbook with Problems and Solutions

By M Knoop, N Madsen, and R C Thompson

World Scientific

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Electromagnetic trapping, which is the confinement of charged particles by the use of combined electric and magnetic fields, has emerged as a very versatile tool for manipulating charged particles. It is extremely useful for performing precise measurements, for mass spectroscopy, plasma physics, and antihydrogen creation, as well as for applications including atomic clocks and trapped-ion quantum computers.

The textbook collects lectures on charged-particle trapping given by the major experts in the field at the Les Houches Winter School in January 2015. It discusses both the fundamental physics of this technique and its different applications. The first lectures are dedicated to explaining how to trap charged particles and the basic properties of Penning and radio-frequency (RF) traps. Following chapters are dedicated to practical problems related to trapping – vacuum systems and cooling techniques (including laser cooling), in particular, are discussed. Simulations, plasma physics, antihydrogen physics and other applications are then explained.

Being the result of lectures given to young physicists, the book is targeted towards advanced undergraduate and graduate students who are new to the topic. All of the chapters are accompanied by worked problems to help students to check their understanding of the subjects.

An Introduction to Graphene Plasmonics

By P A D Gonçalves and N M R Peres

World Scientific

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Graphene plasmonics is a fast-developing area of research, for which no textbook yet exists. Previous books on plasmonics have focused on the use of conventional metals, while scientific articles on graphene plasmonics present the subject in a fragmented and not very pedagogical way. This book aims to fill this gap in the scientific literature.

A plasmon is a quantum of plasma oscillation – the minimum amount of oscillations of the electron density in conductive media. The world “plasmonics” is used to refer to the transfer of information through nanoscale structures by means of surface plasmons, which are plasmons – confined to the surface – that can be excited by photons and electrons.

In 2011 it was demonstrated that plasmonic effects in graphene (which is a two-dimensional material, therefore all surface) could be controlled optically by shining electromagnetic radiation onto a periodic grid of graphene micro-ribbons. This was the start of a new and intriguing branch of research at the interface between condensed-matter physics and photonics.

The authors have aimed to make their book as self-contained as possible, so they discuss all of the relevant aspects of the topic. Starting from graphene’s electronic properties, and plasmonics at metal–dielectric interfaces and in metal thin films, the book gradually dives into the field of graphene plasmonics. Several chapters are dedicated to different methods of inducing surface plasmon polaritons in this material, and there are appendices that give calculations and in-depth analysis on some of the topics covered.

The book is intended both for students of and newcomers to the field, but it could also be a reference for researchers already working on graphene plasmonics.

Macroscopic Electrodynamics: An Introductory Graduate Treatment

By W Wilcox and Chris Thron

World Scientific

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This book provides a comprehensive treatment of classical electrodynamics for graduate students of physics and engineering. The word “macroscopic” in the title refers both to the large-scale manifestations of the theory and to the applications of the so-called macroscopic Maxwell equations to idealised media, which are discussed in the book.

The topics are carefully explained, using precise but informal language that would appeal to younger students. On the mathematics side, a background in advanced calculus, linear algebra and variational methods is needed by the reader, as is a basic understanding of electrodynamics on the physics side. A large set of exercises is integrated into the text. They are designed to help students to get to grips with concepts and practical methods, but also to stimulate their intuition, rather than their ability in calculus.

After an introduction on the basic concepts of electrostatic and magnetostatic fields and interactions, the authors move on to extending such concepts to time-dependent phenomena. A whole section is then dedicated to the properties, interactions and applications of electromagnetic waves. Finally, a chapter covers relativity and electromagnetic formalism. Hints of many other topics are given in conclusion, both to stimulate the curiosity of student readers and guide them towards further studies.

Besides an appendix on units, a guide to problems is also included, in which the solutions to the exercises that are not integrated in the text are provided.

PWA90: A Lifetime Of Emergence

By P Chandra, P Coleman, G Kotliar, P Ong, D L Stein and C Yu (eds)

World Scientific

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In December 2013, a community of physicists gathered in Princeton on the occasion of Philip Warren Anderson’s 90th birthday to celebrate the achievements of his remarkable career. This book is the result of the event, and collects a number of intriguing and lively contributions from Anderson’s students, collaborators and distinguished colleagues, which will appeal to both high-energy and condensed-matter physicists.

The description of a single helium atom is familiar to any undergraduate student, but a collection of many helium atoms produces unexpected phenomena ranging from superfluidity to magnetic phases. This occurrence could be concisely summarised by saying that “more is different”, as Anderson (who shared the 1977 Nobel Prize in Physics with N Mott and J Van Vleck for their fundamental theoretical investigations of the electronic structure of magnetic and disordered systems) wrote in the title of a pedagogical article published in 1972. As Anderson would put it, “the ability to reduce everything to simple fundamental laws does not imply the ability to start from these laws and reconstruct the whole universe.” The so-called “emergentism” appears then as a possible synthesis between the thesis of the reductionism (often attributed to particle physics) and the antithesis of pure constructivism. This third perspective can be appreciated in this book.

Relatively short, it contains accurate and stimulating accounts of various hot topics that are popular in condensed-matter theory, starting from the ubiquitous mechanism of the localisation of waves in random media (often referred to as “Anderson localisation”). The connections between superfluidity, superconductivity and the way that massless gauge bosons acquire a mass are explored in the contribution of Frank Wilczek (who shared the 2004 Nobel Prize in Physics with David Gross and David Politzer, for the discovery of asymptotic freedom).

The historical origins of Anderson’s paper describing the relation between plasmons, gauge invariance and mass are masterly reviewed by Ed Witten (professor of mathematical physics at the Institute for Advanced Study in Princeton, US).

In a nutshell, Anderson’s idea was that the scalar zero-mass excitations of a superconducting neutral Fermi gas become longitudinal plasmon modes of finite mass when the gas is charged. Higgs described his mechanism as the relativistic analogue of Anderson’s idea, whose origin is instead conceptually motivated by a series of contributions by J Schwinger, speculating that gauge fields can become massive thanks to strong coupling effects in two space–time dimensions. This field theory in two dimensions is often used to introduce the concept of “bosonisation”.

The contributions contained in PWA90 can be considered as an extended introduction to a more technical treatise (very popular among practitioners in the late 1980s and early 1990s) entitled Basic Notions of Condensed Matter Physics (Benjamin-Cummings 1984) and edited by P W Anderson together with C C Yu. In that book, Anderson managed to stress the connection between symmetry breaking, emergent phenomena and condensed-matter theory. While more than 30 years separate the two books, their common goals and inspirations remain intact: different areas of physics can and must be cross-fertilised because, ultimately, physics is one.

Experimental Studies of Neutrino Oscillations

By Takaaki Kajita

World Scientific

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This book on neutrino oscillations is mainly of historic interest. It consists of seven chapters that reproduce review articles written by the 2015 Nobel laureate in physics, Takaaki Kajita, which were previously published between 2000 and 2009, either in journals or in international conference proceedings (all World Scientific publications). The articles describe experiments on solar and atmospheric neutrino interactions performed using the Kamiokande and SuperKamiokande water Cherenkov detectors installed in the Kamioka mine in Japan. These experiments resulted in the 1998 discovery of atmospheric muon-neutrino (νμ) oscillation by observing νμ disappearance over a flight-path length of the order of the Earth’s radius. In addition, they have provided important hints on the oscillation of solar neutrinos, which was conclusively demonstrated in 2002 by the SNO experiment in Canada (the 2015 Nobel Prize in Physics was also awarded to A B McDonald for his leading role in this experiment).

Chapter 1 includes a short description of results from experiments using neutrinos from accelerators. These include the K2K experiment in Japan and MINOS at Fermilab, which confirmed the atmospheric neutrino oscillation, and the KamLAND experiment (also located in the Kamioka mine), which has observed the disappearance of electron antineutrinos (νe) from nuclear reactors over an average baseline of 180 km, therefore verifying solar-neutrino oscillation with “man-made” neutrinos. Although not up to date, the values of the oscillation parameters Δm212, Δm223, θ12 and θ23 quoted in this book are quite precise and close to the current ones.

Future directions and plans in the study of neutrino oscillations are also described. In particular, methods and plans to measure the mixing angle θ13 (not yet measured in 2009) using neutrinos from both reactors and accelerators are discussed, as well as the impact of the θ13 value on the possible detection of CP violation in the neutrino sector. Although the book was published in 2016, on this subject it is obsolete because θ13 has been measured in the first half of the current decade by a number of experiments and is presently known to better than 10%.

Finally, chapter 2, written with four co-authors, addresses the physics capabilities of possible future experiments using a water Cherenkov detector with a mass of 1 Mton.

A Lesson for the Future of Our Science: My Testimony on Lord Patrick M S Blackett

By A Zichichi

World Scientific

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The book is a tribute to the great experimental physicist Lord Patrick M S Blackett, written by one of his pupils at the Sphynx Observatory, Antonio Zichichi. Blackett is well known for his work on cloud chambers and cosmic rays, which earned him the Nobel Prize in Physics in 1948.

The author offers his personal testimony, from the first time he heard Blackett’s name to when he went to work with him, and then about the research he could be involved in. He provides a profile of his subject while giving an overview of Blackett’s work and, in particular, of his most significant discoveries, including the so-called vacuum-polarisation effect, the first example of “virtual physics”, and strange particles. The important implications of Blackett’s pioneering contribution to sub-nuclear physics are also discussed.

The book also presents a portrait of the world of physics during those times, and gives insights into life and research at CERN, as well as about Blackett’s ideas. He was very interested in the role of science in the culture of the time. He was convinced that physicists should be directly engaged with communicating to society, which should be informed about the contribution of science to the progress of our civilisation.

Rich in personal anecdotes, pictures and appendices, the book could appeal to physicists and students who are also interested in the history of science and in the human dimension of great scientists. As a final point, the layout and editing could be improved.

Neutrino Oscillations: A Practical Guide to Basics and Applications

By Fumihiko Suekane

Springer

Also available at the CERN bookshop

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This is a detailed and up-to-date textbook on neutrino oscillations. After a short historical introduction (chapter 1), chapter 2 contains a concise, yet quite complete, presentation of neutrino theory in the Standard Model, including neutrino interactions and production in pion, muon and nuclear beta decay. The basic ideas of particle oscillation in quantum mechanics are introduced in chapter 3, and a detailed theory of neutrino oscillations is presented in chapter 4 – first in a two-neutrino approximation, then generalised to the three neutrino flavours – for oscillations both in vacuum and matter. In addition to the usual neutrino description in terms of plane waves, this chapter includes the mathematical treatment of a wave-packet oscillation, which helps in understanding neutrino oscillations over astronomical distances.

Chapter 5 contains a description of past and present oscillation experiments and of the results published prior to 2014, including the measurement of θ13. These results are again summarised in chapter 6, where the current knowledge of three-neutrino oscillation parameters is described. Future experiments to measure the remaining oscillation parameters (the so-called neutrino mass hierarchy and the CP-violation phase) are discussed in chapter 7, together with oscillation anomalies observed by a number of experiments (LSND, MiniBoone, Gallium and recent re-analyses of old reactor experiments). These anomalies, if confirmed, would imply the existence of at least one additional “sterile” neutrino with a mass in the order of 1 eV, requiring a mixing matrix of larger dimensions and more oscillation parameters. Chapter 7 also includes a discussion of the difference between Dirac and Majorana neutrinos, and the implications of direct measurements of the effective νe mass and of searches for neutrinoless double beta decay. Finally, chapter 8 contains a useful appendix summarising all the symbols, abbreviations and formulae used in the book.

The textbook contains all of the information that anybody interested in neutrino oscillations would like to know. Physicists involved in neutrino experiments should each have a copy in their private libraries.

Romania becomes CERN Member State

Romania has become the 22nd Member State of CERN, having acceded to the Organization’s founding convention, which is deposited with UNESCO, on 17 July. The accession crowns a period of co-operation that stretches back 25 years. “This is a very special moment for Romania and its relationship with CERN,” says ambassador Adrian Vierita, Romania’s permanent representative to the United Nations in Geneva.

Bilateral discussions between the Romanian government and CERN began in 1991. Aspiring to become a Member State and therefore to contribute fully to the governance of the laboratory, Romania submitted its formal application to join CERN in April 2008.

Today, Romania has around 100 visiting scientists at CERN and a particularly strong presence in the LHC experiments ATLAS, ALICE and LHCb, in addition to the DIRAC, n_TOF and NA62 experiments. “The accession of Romania to full CERN membership underlines the importance of European research collaboration in the quest to understand nature at its most fundamental level,” says the president of CERN Council, Sijbrand de Jong. “United, we can do so much more than as individual countries.” The Romanian flag will be raised alongside 21 others at the CERN entrance on 5 September.

LHC experiments weigh up 2016 data

The 38th International Conference on High-Energy Physics (ICHEP 2016) took place on 3–10 August in Chicago, US. Among numerous results presented, the LHC experiments released their latest analyses of 13 TeV proton–proton collision data recorded in 2016.

Based on a data set of 12 fb–1, ATLAS released many new results including 50 conference notes. Highlights included new and highly precise measurements of WZ production that constrain anomalous boson couplings. ATLAS also searched in many final states for signs of direct production of supersymmetric and other new particles from beyond the Standard Model. No compelling evidence was found. In particular, the intriguing hint of a possible new state with a mass of 750 GeV decaying into photon pairs seen in the 2015 data has not reappeared. The larger data set  also allowed ATLAS to “rediscover” the Higgs boson with high statistical significance.

The CMS collaboration presented more than 70 new results based on an integrated luminosity of 13 fb–1, also including a rediscovery of the Higgs. In line with the findings from ATLAS, an updated search for a 750 GeV diphoton resonance by CMS did not confirm the excess observed previously, setting a limit on its cross-section of 1.5 fb at the 95% CL. Searches for supersymmetric and exotic particles also showed no significant excesses, allowing mass limits to be increased by a few hundred GeV. New massive Z bosons up to 4 TeV and string resonances decaying into pairs of jets up to 7.4 TeV have now been excluded, while searches for dark matter exclude mediator masses up to 2 TeV in several standard scenarios.

LHCb presented many interesting new results in the domain of flavour physics. A particular highlight was the discovery of the decay mode B0 K+K, which is the rarest B-meson decay into a hadronic final state ever observed, as well as searches for CP violation in the charm system. Another first was a measurement of the photon polarisation in radiative decays of Bs mesons, and determinations of the production cross-sections of several key processes at a collision energy of 13 TeV – some of which at first sight are at variance with current predictions.

Based on lead–lead collisions with an energy of 5 TeV per nucleon pair, the ALICE collaboration presented new measurements of the properties of the quark–gluon plasma. These included fundamental measurements of the production of quarkonium at the highest collision energy ever reached at an accelerator. ALICE also measured the viscosity of the plasma at the new energy, showing that the system still behaves almost as an ideal liquid.

• CERN Courier went to press as ICHEP 2016 got under way. A full report will appear in the next issue.

New bunch-production scheme breaks luminosity record

The LHC relies on the injector complex to deliver proton beams with well-defined transverse and longitudinal characteristics, which fold directly into luminosity performance. On 16 July, LHC Operations made use of a new bunch-production scheme called Batch Compression Merging and Splitting (BCMS) which offers significantly lower transverse beam size. Although the LHC has already broken several performance records this year, the new scheme increased the peak luminosity of the LHC by around 20% and set a new record of 1.2 × 1034 cm–2s–1.

Proton beams emerging from Linac2 in the LHC’s accelerator chain are injected sequentially into each of the four rings of the Proton Synchrotron Booster (PSB) using a multiturn injection process. The total beam intensity per ring is controlled by varying the number of PSB turns during which beam is injected. The transverse emittance (a combined measure of the beam’s transverse size and angular divergence) is also determined by the multiturn nature of the injection process, and in general more injected protons translates to a larger transverse emittance. The eventual number of bunches and their temporal spacing are governed by radio-frequency (RF) gymnastics in the Proton Synchrotron (PS), which injects protons into the Super Proton Synchrotron (SPS) – from where they are fed into the LHC.

The nominal scheme for LHC beam production is based on injecting four and then two bunches from the PSB into the PS. The six PSB bunches are injected into the PS RF “harmonic 7”. The harmonic number is the number of bunch slots – or RF buckets – available in the full circumference of the ring, and this parameter is fully controlled by the RF system. Each of the six bunches is then split into three to reach harmonic 21, and then split into two twice more to result in 72 bunches spaced by 25 ns. To reduce the emittance, it is desirable to inject fewer turns from Linac2 into the PSB and to reduce the bunch-splitting factor in the PS, while still delivering nominal bunch population for 25 ns beam.

The new BCMS scheme makes maximal use of the PSB rings by taking eight bunches (four plus four) into the PS on harmonic 9. A batch compression is then performed by incrementing the harmonic number from harmonic 9 to 14, after which a bunch-merging puts the harmonic number back to 7 (see figure). From this point onwards, the RF gymnastics are similar to those used for the nominal beam but the number of bunches produced is different: eight bunches are merged into four, split by three, two and two again. This results in 48 bunches spaced by 25 ns being injected into the SPS, which is less than the nominal 72 bunches. The scheme wins by taking lower intensities and thus smaller bunches into the PS, and then establishing the basis for the nominal bunch population in the compression and merging process.

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