Praxis Archives – Page 129 of 183

Physics of Intensity Dependent Beam Instabilities

by K Y Ng, World Scientific. Hardback ISBN 9812563423, £52 ($86).

This book comprehensively covers intensity-dependent particle-beam instabilities in accelerating rings. It briefly reviews the concept of wake potentials and coupling impedances in the vacuum chamber, and then discusses static and dynamic solutions to their effects on particle beams. It separately emphasizes proton and electron machines. Other topics include Landau damping, Balakin–Novokhatsky–Smirnov damping, Sacherer’s integral equations, saw-tooth instability, Robinson stability criteria, beam loading, transition crossing and collective instability issues of isochronous rings. It provides a thorough description of experimental observations and discusses cures for the instabilities.

Laser-driven Particle Accelerators: New Sources of Energetic Particles and Radiation

by Keith Burnett, Dino Jaroszynski and Simon Hooker (eds), The Royal Society. Paperback ISSN 1364503X, £100 ($170).

The strong electromagnetic fields that are generated when intense laser pulses interact with plasma could produce a new generation of extremely compact particle accelerators. Laser-driven plasma accelerators are potentially versatile sources of energetic particle beams and coherent radiation that ranges from terahertz frequencies to X-rays. This issue of Philosophical Transactions of the Royal Society A contains papers by leading experts, beginning with basic concepts in plasma accelerators and the status and evolution of plasma-wakefield particle accelerators. It includes inverse free-electron lasers, high-intensity laser-driven proton acceleration and femtosecond electron diffraction.

An Invitation to Astrophysics

by Thanu Padmanabhan, World Scientific. Hardback ISBN 9812566384, £38 ($66). Paperback ISBN 9812566872, £21 ($36).

This book describes several aspects of astrophysics and cosmology in a way that a physicist or beginner in astrophysics can understand. It emphasizes current research and exciting new frontiers, and introduces complex results with simple, novel derivations, which strengthen the conceptual understanding of the subject. The book has more than 100 exercises, which will benefit students. Undergraduate and graduate physics and astrophysics students, as well as physicists who are interested in quickly grasping astrophysical concepts, will find this book useful.

Analytical Mechanics

by Antonio Fasano and Stefano Marmi, Oxford University Press. Hardback ISBN 9780198508021, £49.50 ($89.50).

Analytical mechanics is the investigation of motion with the rigorous tools of mathematics – a classical subject with fascinating developments and still rich with open problems. This book is intended to fill a gap between elementary expositions and more advanced material, explaining ideas and showing applications using plain language and “simple” mathematics. Basic calculus is enough for the reader to understand this volume; any further mathematical concepts are fully introduced in simple language.

Time and Matter: Proceedings of the International Colloquium on the Science of Time

by Ikaros I Bigi and Martin Faessler (eds), World Scientific. Hardback ISBN 9812566341, £56 ($98).

Time and matter are the most fundamental concepts in physics and in any science-based description of the world around us. Quantum theory has, however, revealed many novel insights into these concepts in non-relativistic, relativistic and cosmological contexts. The implications of these novel perspectives have been realized and, in particular, probed experimentally only recently. The papers in this publication discuss these issues in an interdisciplinary fashion from philosophical and historical perspectives. The leading contributors, including Nobel laureates T W Hänsch and G ‘t Hooft, address both experimental and theoretical issues. Physicists, philosophers, historians of science, and graduate physics students will find this an interesting read.

Handbook on Secondary Particle Production and Transport by High-energy Heavy Ions

by Takashi Nakamura and Lawrence Heilbronn, World Scientific. Hardback ISBN 9812565582, £33 ($58).

This handbook is a timely resource for the rapidly growing field of heavy-ion transport-model theory and its applications in accelerator development, heavy-ion radiotherapy and shielding of accelerators, as well as in space. Data from more than 20 years of experiments in the production of secondary neutrons and spallation products are contained in the handbook and on the accompanying CD. Transport modellers and experimentalists will find the detailed descriptions of the experiments and subsequent analyses valuable in utilizing the data for their applications.

Adventures in Theoretical Physics: Selected Papers with Commentaries

by Stephen L Adler, World Scientific. Hardback ISBN 9812563709 £62, ($108). Paperback ISBN 9812565221 £33, ($58).

From 1964–1972, Stephen L Adler wrote seminal papers on high-energy neutrino processes, current algebra, soft pion theorems, sum rules and perturbation-theory anomalies, which helped lay the foundations for the current Standard Model of elementary-particle physics. These papers are reprinted here with detailed historical commentaries describing how they evolved, their relation to other work in the field and their connection to recent literature. The commentaries and reprints also cover later important work by Adler on a range of topics in fundamental theory, phenomenology and numerical methods. This book is a valuable resource for graduate students and researchers, and for historians of physics in the final third of the 20th century.

Linear Collider Physics in the New Millennium

by Keisuke Fujii, David J Miller and Amarjit Soni (eds), World Scientific. Hardback ISBN 9812389083, £60 ($98).

The high-energy electron–positron linear collider is expected to provide crucial clues to many of the fundamental questions of our time. What is the nature of electroweak symmetry breaking? Does a Standard Model Higgs boson exist or does nature take the route of supersymmetry, technicolour, extra dimensions or none of the these? This book contains articles by experts on many of the most important topics on which the linear collider will focus. It is aimed primarily at graduate students but will be useful to any researcher interested in the physics of the next-generation linear collider.

Mather and Smoot share Nobel for precise observations of the CMB

The Nobel Prize in Physics 2006 recognizes research that studies the young universe, before the first stars were born and before galaxies began to form. John Mather of the NASA Goddard Space Flight Center (GSFC) and George Smoot of the Lawrence Berkeley National Laboratory share the prize “for their discovery of the blackbody form and anisotropy of the cosmic microwave background (CMB) radiation”. Both physicists’ work involved the Cosmic Background Explorer (COBE) satellite, which in the early 1990s provided an exciting new view of CMB radiation. This carries the imprint of the universe as it was some 300,000 years after the Big Bang, when radiation and matter decoupled and atoms began to form. COBE’s findings strongly supported the Big Bang and began to turn cosmology into a precise observational science.

CCEnew3_11-06 — John Mather during a press conference held at NASA headquarters in Washington, DC. Image: NASA/Bill Ingalls.

Mather and Smoot share a long-standing interest in cosmology. For Smoot this followed a PhD in 1970 in particle physics, and he soon concentrated on producing experimental data about the early universe – in particular to study the CMB, the discovery of which by Arno Penzias and Robert Wilson in 1964 had, in Steven Weinberg’s words, shown that there was such a thing as an early universe to study. (Penzias and Wilson went on to share the Nobel prize in 1978.) By 1974, Smoot had submitted a proposal to NASA to measure and map the CMB in search of imprints of what had happened at earlier epochs.

At the same time, Mather, with an interest in infrared astronomy, led efforts for the first proposal for COBE. After moving to the GSFC, he became study scientist (1976) and then project scientist (1988) for COBE, as well as principal investigator for the Far Infrared Absolute Spectrophotometer (FIRAS) on board COBE. Smoot, meanwhile, became principal investigator of COBE’s Differential Microwave Radiometer (DMR).

The original plan was for a space shuttle to launch COBE, but shuttle operations came to a standstill in 1986 after Challenger‘s horrific accident. However, Mather and his collaborators negotiated the use of a rocket and launched the satellite in November 1989. The FIRAS, designed to measure the CMB radiation spectrum with unprecedented precision, soon revealed a blackbody spectrum perfect to within 50 ppm, corresponding to 2.725±0.002 K, formidable evidence for the Big Bang.

CCEnew4_11-06 — Joint Nobel prize-winner George Smoot enjoys the accolades at a press conference held at Lawrence Berkeley National Laboratory. Image: Peg Skorpinski.

More slowly, Smoot and his colleagues analysed the DMR measurements to create maps of the sky that revealed tiny temperature variations (about 10 ppm) in the generally uniform radiation. These indicated density variations in the primordial universe, which would eventually lead to regions of galaxies and clusters of galaxies separated by empty space. The data proved invaluable in constraining models of the early universe.

A thousand physicists, engineers and others involved in the project both before and after the satellite’s launch contributed to COBE’s success. The satellite took data until the end of 1993, and in 2003 its successor, the Wilkinson Microwave Anisotropy Probe, provided an even more detailed look, measuring temperature fluctuations to millionths of a degree.

Hawking brings the origins of the universe to CERN

Stephen Hawking is the best known physicist alive. His book A Brief History of Time was a bestseller around the world, but sometimes his star status obscures his continued activity at the frontiers of theoretical physics. For some 40 years his research has centred on theoretical cosmology and black holes. When he started work as a theoretical physicist in the 1960s, particle physics and cosmology seemed to be separate worlds, but now these topics are increasingly intertwined. So it was not surprising that Hawking should want to visit the Theory Unit at CERN, to meet fellow theorists and give a seminar on his current work.

CCEhaw1_11-06 — Dwarfed by CMS, Hawking talks to CMS spokesperson-elect Jim Virdee, left, and theorist Thomas Hertog, right, who works with Hawking on quantum cosmology.

In the 1960s, Hawking and Roger Penrose developed the famous singularity theorems in general relativity, which provided a precise set of general conditions under which the existence of gravitational collapse is inevitable, leading to black holes. In particular Hawking provided a fairly complete theory of black holes and their classical properties, which led to intriguing analogies with the laws of thermodynamics. An important application of this work led to the theory that our universe began with a Big Bang, with an initial singularity.

Perhaps more famously, however, in the early 1970s Hawking shocked the world by showing that if one considered quantum mechanics (quantum field theory) in the presence of black holes, these are not black after all, but rather they emit radiation with a thermal spectrum and a temperature that depends only on the basic characteristics of the black-hole state: namely, its mass, angular momentum and charge. In the simplest case, the temperature is inversely proportional to the mass. This phenomenon is known as black-hole evaporation.

CCEhaw2_11-06 — Hawking during his tour of the ATLAS cavern, with, from left to right, theorist Thomas Hertog, ATLAS spokesperson Peter Jenni and ATLAS deputy spokesperson Fabiola Gianotti.

Hawking went even further, however, and made the provocative proposal that the laws of quantum mechanics must be changed in the presence of black holes. Specifically, quantum information and quantum coherence are irreversibly lost in the formation and evaporation of black holes. This proposal has generated much work in the past 30 years, and we are only now beginning to understand that quantum mechanics does not after all need to be modified. However, many aspects of the theory of quantum gravity need to be understood in detail before we can claim that the paradox has been resolved.

The Hawking evaporation phenomenon also has basic observational consequences. If a black hole has a small mass, then it will radiate more copiously, so we can put an observational limit on the size of remnant black holes from the origin of the universe. Furthermore, if CERN’s Large Hadron Collider (LHC) produces mini black holes we know that they will evaporate with a nearly thermal spectrum, an important characteristic in identifying them.

CCEhaw3_11-06 — In the general colloquium that he delivered at CERN, Hawking talked on one of his favourite topics: the origin of the universe.

Currently Hawking is working on quantum cosmology. He is studying a top-down approach to cosmology that combines the string landscape with the scenario of no-boundary initial conditions. The theory seminar that he presented at CERN was based on this work in collaboration with Thomas Hertog, who is currently a fellow with the Theory Unit.

In his general colloquium, which attracted an audience of 850, Hawking discussed one of his favourite topics – the origin of the universe. He argued that thanks to what we have learned over the past 100 years we may finally have a scientific way to address this subject. General relativity predicts that the universe, and time itself, would have begun in a Big Bang. It also predicts that time ends in black holes. The discoveries of the cosmic microwave background radiation and of black holes support these conclusions; adding in quantum mechanics begins to yield the rudiments of a theory of structure in the observed universe. However, much still remains to be understood on this subject, although as Hawking argued in his seminar, a scientific cosmogony is both possible and within reach of theoretical and experimental work.

During his stay at CERN, Hawking also visited the ATLAS and CMS experiments, as well as the tunnel of the LHC, where installation work proceeds rapidly. He was interested in the details of the experiments, and in the possible discovery of mini black holes. He also met with the director-general, Robert Aymar, and their discussion covered topics ranging from open-access publishing to the start-up of the LHC. Congratulating Aymar and the CERN community on their scientific work, he commented “You have an exciting two years ahead of you.”

Topics

Reset your password

Registration complete