By Tom Lancaster and Stephen J Blundell Oxford University Press
Hardback: £65 $110
Paperback: £29.99 $49.95
Also available as an e-book, and at the CERN bookshop
Many readers of CERN Courier will already have several introductions to quantum field theory (QFT) on their shelves. Indeed, it might seem that another book on this topic has missed its century – but that is not quite true. Tom Lancaster and Stephen Blundell offer a response to a frequently posed question: What should I read and study to learn QFT? Before this text it was impossible to name a contemporary book suitable for self-study, where there is regular interaction with an adviser but not classroom-style. Now, in this book I find a treasury of contemporary material presented concisely and lucidly in a format that I can recommend for independent study.
Quantum Field Theory for the Gifted Amateur is in my opinion a good investment, although of course one cannot squeeze all of QFT into 500 pages. Specifically, this is not a book about strong interactions; QCD is not in the book, not a word. Reading page 308 at the end of subsection 34.4 one might expect that some aspects of quarks and asymptotic freedom would appear late in chapter 46, but they do not. I found the word “quark” once – on page 308 – but as far as I can tell, “gluon” did not make its way at all into the part on “Some applications from the world of particle physics.”
If you are a curious amateur and hear about, for example, “Majorana” (p444ff) or perhaps “vacuum instability” (p457ff, done nicely) or “chiral symmetry” (p322ff), you can start self-study of these topics by reading these pages. However, it’s a little odd that although important current content is set up, it is not always followed with a full explanation. In these examples, oscillation into a different flavour is given just one phrase, on p449.
Some interesting topics – such as “coherent states” – are described in depth, but others central to QFT merit more words. For example, figure 41.6 is presented in the margin to explain how QED vacuum polarization works, illustrating equations 41.18-20. The figure gives the impression that the QED vacuum-polarization effect decreases the Coulomb–Maxwell potential strength, while the equations and subsequent discussion correctly show that the observed vacuum-polarization effect in atoms adds attraction to electron binding. The reader should be given an explanation of the subtle point that reconciles the intuitive impression from the figure with the equations.
Despite these issues, I believe that this volume offers an attractive, new “rock and roll” approach, filling a large void in the spectrum of QFT books, so my strong positive recommendation stands. The question that the reader of these lines will now have in mind is how to mitigate the absence of some material.
Technologies developed for fundamental research in particle, astro-particle and nuclear physics have an enormous impact on everyday lives. To push back scientific frontiers in these fields requires innovation: new ways to detect one signal in a wealth of data, new techniques to sense the faintest signals, new detectors that operate in hostile environments, new engineering solutions that strive to improve on the best – and many others.
The scientific techniques and high-tech solutions developed by high-energy physics can help to address a broad range of challenges faced by industry and society – from developing more effective medical imaging and cancer diagnosis through positron-emission tomography techniques, to developing the next generation of solar panels using ultra-high vacuum technologies. However, it is difficult and costly not only for many organizations to carry out the R&D needed to develop new applications, products and processes, but also for scientists and engineers to turn their technologies into commercial opportunities.
The aim of the high-energy physics technology-transfer network – HEPTech – is to bring together leading European high-energy physics research institutions so as to provide academics and industry with a single point of access to the skills, capabilities, technologies and R&D opportunities of the high-energy physics community in a highly collaborative open-science environment. As a source of technology excellence and innovation, the network bridges the gap between researchers and industry, and accelerates the industrial process for the benefit of the global economy and wider society.
HEPTech is made up of major research institutions active in particle, astroparticle and nuclear physics. It has a membership of 23 institutions across 16 countries, including most of the CERN member states (see table). Detailed information about HEPTech member organizations and an overview of the network’s activities are published annually in the HEPTech Yearbook and are also available on the network’s website.
So, how was the network born? Jean-Marie Le Goff, the first co-ordinator and present chairman of HEPTech, explains: “Particle physics is a highly co-operative environment. The idea was to spread that spirit over to the Technology Transfer Offices.” So in 2008 a proposal was made to the CERN Council to establish a network of Technology Transfer Offices (TTOs) in the field of particle physics. The same year, Council approved the network for a pilot phase of three years, reporting annually to the European Strategy Session of Council. In the light of the positive results obtained over those three years, Council approved the continuation of the network’s activities and its full operation. “Since then it has grown – both in expanding the number of members and in facilitating bodies across Europe that can bring innovation from high-energy physics faster to industrial exploitation”, says Le Goff.
The primary objective of the HEPTech network is to enhance technology transfer (TT) from fundamental research in physics to society. Therefore, the focus is on furthering knowledge transfer (KT) from high-energy physics to other disciplines, industry and society, as well as on enhancing TT from fundamental research in physics to industry for the benefit of society. The network also aims to disseminate intellectual property, knowledge, skills and technologies across organizations and industry, and to foster collaborations between scientists, engineers and business. Another important task is to enable the sharing of best practices in KT and TT.
HEPTech’s activities are fully in line with its objectives. To foster the contacts with industry at the European level, the network organizes regular academia–industry matching events (AIMEs). These are technology-themed events that provide matchmaking between industrial capabilities and the needs of particle physics and other research disciplines. They are HEPTech’s core offering to its members and the wider community, and the network has an active programme in this respect. Resulting from joint efforts by the network and its members, the AIMEs usually attract about 100 participants from more than 10 countries (figures from 2014). Last year, the topics ranged from the dissemination of micropattern-gas-detector technologies beyond fundamental physics, through potential applications in the technology of controls, to fostering academia–industry collaboration for manufacturing large-area detectors for the next generation of particle-physics experiments, and future applications of laser technologies.
HEPTech has teamed up with the work package on relations with industry of the Advanced European Infrastructures for Detectors at Accelerators (AIDA) project
“The topics of the events are driven on the one hand by the technologies we have – it’s very much a push model. On the other hand, they are the results of the mutual effort between the network and its members, where the members have the biggest say because they put in a lot of effort”, says Ian Tracey, the current HEPTech co-ordinator. He believes that a single meeting between the right people from academia and industry is only the first step in the long process of initiating co-operation. To establish a project fully, the network should provide an environment for regular repetitive contact for similar people. To address this need, HEPTech looks at increasing the number of AIMEs from initially four up to eight events per year.
“The benefit of having HEPTech as a co-organizer of the AIMEs is clearly the European perspective”, says Katja Kroschewski, head of TT at DESY. “Having speakers from various countries enlarges the horizon of the events and allows coverage of the subject field across Europe. It is different from doing a local event – for instance, having companies only from Hamburg or just with the focus on Germany. As the research work concerned has an international scope, it absolutely makes sense to organize such events. It is good to have the input of HEPTech in shaping the programme of the event and to have the network’s support within the organizing committee as well.”
HEPTech has teamed up with the work package on relations with industry of the Advanced European Infrastructures for Detectors at Accelerators (AIDA) project (which was co-funded by the European Commission under FP7 in 2011–2014), to organize AIMEs on detectors, with a view to fostering collaboration with industry during the pre-procurement phase. A total of seven AIMEs were organized in collaboration with AIDA and the RD51 collaboration at CERN, covering most of the technology fields of importance for detectors at accelerators. HEPTech financed four of them. A total of 101 companies attended the events, giving an average of 14 companies per event. For technology topics where Europe could meet the needs of academia, the percentage of EU industry was about 90% or above, going down to 70% when the leading industry for a technology topic was in the US and/or Asia.
To help event organizers find pertinent academic and industrial players in the hundreds, sometimes thousands, of organizations active in a particular technology, CERN used graph-analysis techniques to develop a tool called “Collaboration spotting”. The tool automatically processes scientific publications, patents and data from various sources, selects pertinent information and populates a database that is later used to automatically generate interactive sociograms representing the activity occurring in individual technology fields. Organizations and their collaborations are displayed in a graph that makes the tool valuable for monitoring and assessing the AIMEs.
However, the findings from AIDA show that it is difficult to conduct an assessment of the impact on industry of an AIME. “To keep a competitive advantage, companies entering a partnership agreement with academia tend to restrict the circulation of this news as much as possible, at least until the results of the collaboration become commercially exploitable,” explains Le Goff. “Although it tends to take some years before becoming visible, an increase in the number of co-publications and co-patents among attendees is a good indicator of collaboration. Clearly some of them could have been initiated at preceding events or under other circumstances, but in any case, the AIME has contributed to fostering or consolidating these collaborations.”
Learning and sharing
Another area of activity is the HEPTech Symposium, which is dedicated to the support of young researchers in developing entrepreneurial skills and in networking. This annual event brings together researchers at an early stage in their careers who are working on potentially impactful technologies in fields related to astro-, nuclear and particle physics. For one week, HEPTech welcomes these Early Stage Researchers from around Europe, providing an opportunity for networking with commercially experienced professionals and TT experts and for developing their entrepreneurial potential.
The first HEPTech Symposium took place in June 2014 in Cardiff. The young researcher whose project attracted the greatest interest was awarded an expenses-paid trip around the UK to look for funding for his project. The 2015 symposium will be held in Prague on 31 May–6 June and will be hosted by Inovacentrum from the Czech Technical University in collaboration with ELI Beamlines and the Institute of Physics of the Academy of Sciences. HEPTech has established a competitive procedure for members that would like to host the event in future. Those interested have to demonstrate their capacity for organizing both a quality training programme and the entertainment of the participants.
CERN Council encouraged HEPTech to continue its activities and amplify its efforts
Providing opportunities for capacity-building and sharing best practice among its members is of paramount importance to HEPTech. The network is highly active in investigating and implementing novel approaches to TT. A dedicated workgroup on sharing best practices responds to requests from members that are organizing events on a number of subjects relevant to the institutions and their TT process. These include, for instance, workshops presenting cases on technology licensing, the marketing of science and technology ond others. Through workshops, the network is able to upscale the skills of its member institutions and provide capacity-building by sharing techniques and different approaches to the challenges faced within TT. These events – an average of four per year – are driven by the members’ enthusiasm to explore advanced techniques in KT and TT, and help to create a collaborative spirit within the network. The members provide significant assistance to the implementation of these events, including lecturers and workshop organization.
Bojil Dobrev, co-convener of the workgroup on best practices provides a recent example of best-practice transfer within the network, in which intellectual property (IP) regulations elaborated by a HEPTech workgroup were successfully used as a basis for development of IP regulations at Sofia University, Bulgaria. In 2013–2014, a survey focusing on the needs and skills of HEPTech members was conducted within the remit of this workgroup. The objectives were to identify the skills and potential of the HEPTech members and their requirement for support through the network, focusing mainly on the early stage (established recently) TTOs. The survey covered all aspects of a TTO’s operation – from organization and financing, through IP activities, start-ups, licensing and contacts with industry, to marketing and promotion. “The survey was used as a tool to investigate the demand of the TTOs. Its outcomes helped us to map HEPTech’s long-term strategy and to elaborate our annual work plan, particularly in relation to training and best-practice sharing”, explains Dobrev.
Taking into consideration the overall achievements of HEPTech and based on the annual reports of the network co-ordinator, CERN Council encouraged HEPTech to continue its activities and amplify its efforts in the update of the European Strategy for Particle Physics in May 2013. The following year, in September, the Council president gave strong support and feedback for HEPTech’s work.
HEPTech’s collaborative efforts with the European Extreme Light Infrastructure (ELI) project resulted in network membership of all three pillars of the project. Moreover, at the Annual Forum of the EU Strategy for the Danube Region, representatives of governments in the Danube countries acknowledged HEPTech’s role as a key project partner in the Scientific Support to the Danube Strategy initiative.
With its stated vision to become “the innovation access-point for accelerator- and detector-driven research infrastructures” within the next three years, HEPTech is looking to expand – indeed, three new members joined the network in December 2014. It also aims to take part in more European-funded projects and is seeking closer collaboration with other large-scale science networks, such as the European TTO Circle – an initiative of the Joint Research Centre of the European Commission, which aims to connect the TTOs of large European public research organizations.
In my journey as a migrant scientist, crossing continents and oceans to serve physics, institutions and nations wherever and whenever I am needed and called upon, CERN has always been the focal point of illumination. It has been a second home to whichever institution and country I have been functioning from, particularly at times of major personal and professional transition. Today, at the completion of yet another major transition across the seas, I am beginning to connect to the community from my current home at Fermilab and Northern Illinois University. Eight years ago, I wrote in this column on “Amazing particles and light” and, serendipitously, I am drawn by CERN’s role in shaping developments in particle physics to comment again in this International Year of Light, 2015.
“For the rest of my life I want to reflect on what light is!”, Albert Einstein exclaimed in 1916. A little later, in the early 1920s, S N Bose proposed a new behaviour for discrete quanta of light in aggregate and explained Planck’s law of “black-body radiation” transparently, leading to a major classification of particles according to quantum statistics. The “photon statistics” eventually became known as the Bose–Einstein statistics, predicting a class of particles known as “bosons”. Sixty years later, in 1983, CERN discovered the W and Z boson at its Super Proton Synchrotron collider, at what was then the energy frontier. In another 30 years, a first glimpse of a Higgs boson appeared in 2012 at today’s high-energy frontier at the LHC, again at CERN.
CERN has again taken the progressive approach of basing such colliders on technological innovation
Today, CERN’s highest-priority particle-physics project for the future is the High-Luminosity LHC upgrade. However, the organization has also taken the lead in exploring for the long-term future the scientific, technological and fiscal limits of the highest energy scales achievable in laboratory based particle colliders, via the recently launched Future Circular Collider (FCC) design effort, to be completed by 2018. In this bold initiative, in line with its past tradition, CERN has again taken the progressive approach of basing such colliders on technological innovation, pushing the frontier of high-field superconducting dipole magnets beyond the 16 T range. The ambitious strategy inspires societal aspirations, and has the promise of returning commensurate value to global creativity and collaboration. It also leaves room for a luminous electron–positron collider as a Higgs factory at the energy frontier, either as an intermediate stage in the FCC itself or as a possibility elsewhere in the world, and is complementary to the development of emerging experimental opportunities with neutrino beams at the intensity frontier in North America and Asia.
What a marvellous pursuit it is to reach ever higher energies via brute-force particle colliders in an earth-based laboratory. Much of the physics at the energy frontier, however, is hidden in the so-called “dark sector” of the vacuum. Lucio Rossi wrote in this column last month how light is the most important means to see, helping us to bridge reality with the mind. Yet even light could have a dark side and be invisible – “hidden-sector photons” could have a role to play in the world of dark matter, along with the likes of axions. And dark energy – is it real, what carries it?
All general considerations for the laboratory detection of dark matter and dark energy lead to the requirement of spectacular signal sensitivities with the discrimination of one part in 1025, and an audacious ability to detect possible dark-energy “zero-point” fluctuation signals at the level of 10–15 g. Already today, the electrodynamics of microwave superconducting cavities offers a resonant selectivity of one part in 1022 in the dual “transmitter–receiver” mode. Vacuum, laser and particle/atomic beam techniques promise gravimeters at 10–12 g levels. Can we stretch our imagination to consider eavesdropping on the spontaneous disappearance of the “visible” into the “dark”, and back again? Or of sensing directly in a laboratory setting the zero-point fluctuations of the dark-energy density, complementing the increasingly precise refinement of the nonzero value of the cosmological constant via cosmological observations?
The comprehensive skills base in accelerator, detector and information technologies accumulated across decades at CERN and elsewhere could inspire non-traditional laboratory searches for the “hidden sector” of the vacuum at the cosmic frontier, complementing the traditional collider-based energy frontier.
Like the synergy between harmony and melody in music – as in the notes of the harmonic minor chord of Vivaldi’s Four Seasons played on the violin, and the same notes played melodiously in ascending and descending order in the universal Indian raga Kirwani (a favourite of Bose, played on the esraj) – the energy frontier and the cosmic frontier are tied together intimately in the echoes of the Big Bang, from the laboratory to outer space.
By Miao Li, Xiao-Dong Li, Shuang Wang and Yi Wang World Scientific
Hardback: £56
E-book: £42
The first volume in the Peking University–World Scientific Advance Physics Series, this book introduces the current state of research on dark energy. The first part deals with preliminary knowledge, including general relativity, modern cosmology, etc. The second part reviews major theoretical ideas and models of dark energy, and the third part reviews some observational and numerical work. It will be useful for graduate students and researchers who are interested in dark energy.
By Alessandro Bettini Cambridge University Press
Hardback: £40 $75
Also available as an e-book, and at the CERN bookshop
The second edition of Alessandro Bettini’s Introduction to Elementary Particle Physics appeared on my doorstep just in time for me to plan my next teaching of the class for beginning graduate students. I liked the first edition very much, and used it for my classes. I like the second edition even better.
First, the level is not overburdened with mathematics, while still introducing enough theory to make meaningful homework assignments. Inspection of the 10 chapter titles – beginning with “Preliminary Notions” of kinematics and the passage of radiation through matter, and ending with the mixing and oscillation of “Neutrinos” – shows that it is clearly written by a knowledgeable experimentalist. The organization illustrates the critical interplay between experiment and theory, but leaves the reader with no doubts that physics is an experimental science.
In the first version, I already liked the presentation of the core material such as the quantum numbers of the pion and their measurement, as well as the more sophisticated presentation of material such as the Lamb shift and the resulting development of quantum electrodynamics. Fortunately, the best of this material has also propagated into the second edition, not always the case even in famous physics texts such as those by Jackson and by Halliday and Resnick, where at least to me, the first editions are better than what followed.
Bettini weaves in a good amount of history of the pivotal discoveries that shaped the Standard Model. Beginning students were not even born when the LHC was designed, and their parents were toddlers when the W and Z bosons were discovered. I was on a bus tour at a recent physics meeting in Europe, when a young postdoc asked me what I had worked on in the past. When I told him UA1, he asked “What’s that?” I was speechless, as were the more senior colleagues around us who overheard our conversation. Bettini gives a must-read, whole and balanced introduction to particle physics, appropriate for a first course.
A companion website from Cambridge University Press has some nice slides of plots and figures. I generally do not like to lecture from my laptop, but sometimes data are essential to the presentation, so this is a real time saver. There is also a new solutions manual for all of the end-of-chapter problems – available only to instructors. I like many of these problems, and will use a mix of them together with my own. Best of all, for the current version, there are some timely additions, most notably the discovery of the Higgs boson and an expanded chapter on neutrino oscillations. I will need to supplement this material with the latest measurements, but I am happy to do that because it reminds me that although progress at the frontier of knowledge is painfully slow, it is not zero. Let us hope that Run 2 at the LHC will necessitate the writing of a third edition of this wonderful book.
By A Campa, T Dauxois, D Fanelli and S Ruffo Oxford University Press
Hardback: £55 $94.95
Also available as an e-book
This book deals with an important class of many-body systems: those where the interaction potential decays slowly for large inter-particle distances and, in particular, systems where the decay is slower than the inverse inter-particle distance raised to the dimension of the embedding space. Gravitational and Coulomb interactions are the most prominent examples, although long-range interactions are more common than thought previously. Intended for Master’s and PhD students, the book tries to acquaint the reader with the subject gradually. The first two parts describe the theoretical and computational instruments needed to study both equilibrium and dynamical properties of systems subject to long-range forces. The third part is devoted to applications to the most relevant examples of long-range systems.
By Lars Brink (ed.) World Scientific
Hardback: £51
Paperback: £22
E-book: £17
This volume is a collection of lectures delivered by the Nobel prizewinners in physics, together with their biographies and the presentation speeches by Nobel Committee members, for the years 2006–2010. The lectures provide detailed explanations of the phenomena for which the laureates were awarded the Nobel prize. The volume includes John Mather and George Smoot, honoured “for their discovery of the blackbody form and anisotropy of the cosmic microwave background radiation”, as well as Yoichiro Nambu “for the discovery of the mechanism of spontaneous broken symmetry in subatomic physics”, and Makoto Kobayashi and Toshihide Maskawa “for the discovery of the origin of the broken symmetry, which predicts the existence of at least three families of quarks in nature”.
The biannual series of international symposia on spin physics plays a leading role at the interface of nuclear and particle physics on one hand, and the study of spin-dependent phenomena in experiment and theory on the other. The series grew from the merger of the five-yearly symposia on polarization phenomena in nuclear reactions, first held in Basel in 1960, and the symposia on high-energy spin, which started in 1974 and had reached the 13th edition by 1998. The joint meetings began as the 14th International Symposium on Spin Physics in 2000. The 21st International Symposium on Spin Physics (SPIN2014) is the first in the series that China has hosted – taking place on the 40th anniversary of the first high-energy spin meeting at Argonne National Laboratory in 1974.
The scientific programme of the symposium series today is based on physics with photons and leptons, spin phenomena in nuclei and nuclear reactions, and new physics beyond the Standard Model. It also includes new technologies related to accelerators, storage rings, polarized targets and polarized beams, and spin physics in medicine is also included. In addition, SPIN2014 extended the topics to incorporate spin in condensed matter, quantum communication and their related applications.
Hosted by Peking University, Beijing, and supported by many renowned research institutions and universities, both inside and outside of China, SPIN2014 took place on 20–24 October 2014. Nearly 300 participants attended from more than 20 countries. With 28 plenary talks and 177 parallel talks, the symposium provided a platform to communicate new results in the field of spin physics and to reinforce academic collaborations with colleagues. It was also an important platform to advertise the academic achievements of Chinese researchers, and to strengthen the importance of Chinese involvement in spin physics. The following gives an overview of the scientific programme.
Hadrons, nucleons and symmetries
A key highlight was the excellent opening plenary talk on the spin structure of the nucleon by Xiangdong Ji of Shanghai Jiao Tong University and the University of Maryland. The quest to determine the origin of nucleon spin challenges the understanding of QCD. There is a worldwide experimental programme underway using spin observables to gain insight into this fundamental question in hadronic physics. The conference also heard more than 50 reports from experiments carried out at Brookhaven, CERN, DESY, Jefferson Lab and KEK on measurements that included inclusive lepton scattering (quark and gluon contributions), proton–proton scattering (gluon contribution, quark flavour decomposition using W-boson production), semi-inclusive deep-inelastic scattering (quark flavour decomposition, transverse-momentum distributions), deeply virtual Compton scattering (quark orbital angular momentum) and fragmentation in electron–positron collisions. There were also discussions on future possible experiments, including polarized Drell–Yan scattering, at Fermilab, the Japan Proton Accelerator Research Complex, the Nuclotron-based Ion Collider fAcility (NICA) in Dubna, and Brookhaven’s Relativistic Heavy-Ion Collider (RHIC). Keh-Fei Liu of the University of Kentucky gave an overview of the exciting developments in lattice QCD in a plenary talk. This was followed by more than 20 presentations on theoretical research into the spin structure of hadrons.
The plenary programme on “Spin Physics in Nuclear Reactions and Nuclei” included a report by Andro Kacharava from the Forschungszentrum Jülich on results from the Cooler Synchrotron (COSY) on nucleon–nucleon scattering using polarization degrees of freedom to probe nuclear forces. Mohammad Ahmed of North Caroline Central University described the latest results on few-body reactions from the High Intensity Gamma-Ray Source Facility at the Triangle Universities Nuclear Laboratory, where both polarized beam and polarized targets were employed, as well as results on Compton scattering from 6Li and 16O. Fifteen talks in the parallel programme were related to spin physics in nuclear reactions and nuclei.
Spin physics plays an important role in studies of fundamental symmetries
Spin physics plays an important role in studies of fundamental symmetries and searches for new physics beyond the Standard Model of particle physics. Plenary talks included reports on the latest result on the weak charge of the proton from parity-violating electron scattering by Dave Mack of Jefferson Lab. Mike Snow of Indiana University presented recent results on hadronic parity-violating experiments such as np → dγ, while Brad Filippone of Caltech provided an overview of the worldwide effort on searches for particle electric-dipole moments (EMDs). Frank Maas described the latest results on dark-photon searches from the University of Mainz and elsewhere. From China, Wei-Tou Ni of National Tsinghua University discussed the role of spin experiments in probing the structure and origin of gravity. Thirteen talks relating to fundamental symmetries were presented in the associated parallel sessions.
Current tools and future facilities
The methods to study spin-dependent effects are fundamental for the spin-physics community. At SPIN2014, the two main areas of interest were acceleration, storage and polarimetry of polarized beams, and sources of polarized ion and lepton beams and polarized targets. Nearly all of these disciplines formed part of the exciting plenary of Annika Vauth of DESY, who discussed the status of beam polarization and the International Linear Collider that could be built in Japan. Nearly 20 parallel talks were devoted to accelerator aspects, among them studies in the US and in China on electron–ion colliders (EICs), at JINR on the use of NICA as a polarized-ion collider, on storage rings for searches for ion EDMs, and on the new tools to be developed to meet these challenges. The operation of existing rings with polarized beams and the steady improvement of their operational parameters were also covered, with RHIC and its amazing performance as the only double-polarized ion collider built so far, and with COSY, which is famous for its stored polarized beams in the medium-energy range and the variety of internal targets.
More than a dozen parallel talks on sources and targets were presented, introduced by Dmitriy Toporkov of the Budker Institute of Nuclear Physics in his plenary on experiments with polarized targets in storage rings, in which he showed the potential of this technique. The review on polarized sources by Anatoli Zelenski of Brookhaven and other parallel talks covered a wide span of polarized beams, from high-intensity electrons for an EIC, to protons, as in H– ions for RHIC, to deuterons for COSY and 3He ions for eRHIC. Chris Keith of Jefferson Lab and other speakers in the parallel sessions covered solid targets polarized by dynamic nuclear polarization or by the brute-force method in several lepton-scattering experiments. Gas targets for H, D and 3He atoms were also discussed.
The conference heard reports on major upgrades of spin capabilities at existing facilities. The status and plans for Jefferson Lab’s 12 GeV upgrade were presented in a plenary talk by associate director Rolf Ent, and Wolfgang Lorenzon of the University of Michigan described the possibility of polarizing the Fermilab proton beam and mounting a programme of polarized Drell–Yan measurements. In Europe, the Mainz Energy-Recovering Superconducting Accelerator provides a high-intensity low-energy polarized electron facility, while COSY has embarked on a major development of new polarized proton- and deuteron-beam capabilities, motivated by experiments to look for nonzero EDMs in light nuclei.
In the US, the QCD community is pursuing a high-luminosity polarized EIC
Alexander Nagaytsev of JINR described the new accelerator NICA under construction in Dubna, together with the planned spin-physics programme, including measurements of polarized Drell–Yan and J/ψ production. In the US, the QCD community is pursuing a high-luminosity polarized EIC. This could be implemented at Brookhaven or Jefferson Lab. The concept has driven R&D in both high-intensity polarized electron guns and a polarized 3He source. In the European Physical Journal A plenary lecture, Zein-Eddine Mezziani of Temple University gave a compelling presentation on the spin science that motivates this new machine. Physicists in China have recently become interested in a similar facility.
Further features
As a novelty, SPIN2014 included a significant programme on spintronics – low-dimensional solid-spin systems exhibiting different quantum effects that can be employed, for example, in quantum computers, metrology, information technology and more. This ambitious field of research and technology is being pursued actively at Tsinghua and Peking Universities, and many other Chinese institutes, and was presented in a public lecture (see below) as well as in parallel sessions that included 20 talks. Apart from spintronics themes, medical applications such as imaging were discussed, a highlight being the beautiful talk by Warren Warren of Duke University on “Imaging with Highly Spin-Polarized Molecules”. There were also two talks on the application of polarized fuel for fusion reactors.
Besides the communication of recent results at the physics frontier, SPIN2014 also organized a lecture on popular science by Qi-Kun Xue from Tsinghua University on “Quantum Anomalous Hall Effect and Information Technology”, attended by more than 100 people from Peking University, Tsinghua University, Beijing University of Posts and Telecommunications, Beihang University and others. A memorial session devoted to the memory of CERN’s Michel Borghini was organized by Alan Krisch of Michigan and Akira Massike of Kyoto, highlighting Borghini’s contributions to the development of solid polarized targets.
A poster session for presenting new research results included Outstanding Poster Awards, sponsored by the Hanscom endowment from Duke University. From 14 posters, three young researchers from the China Institute of Atomic Energy, Tsinghua University and the Institute of Modern Physics of the Chinese Academy of Sciences received awards. The hope is that the poster session and awards will inspire young researchers to work with passion in the area of spin physics. A reception and banquet, and a visit to the nearby Summer Palace, served to bring all of the participants together, enhancing close discussions. They will surely remember SPIN2014 as a stimulating meeting that demonstrated the beauty and vitality of the field – and look forward to the next in the series, which will take place on 26–30 September 2016 at the University of Illinois Urbana-Champaign.
• For more about the organizers and sponsors of SPIN2014, and details of the full programme, visit www.phy.pku.edu.cn/spin2014/.
Seeing has always been a trigger for curiosity – the desire to know reality – and light is a means for bridging reality with our minds. It is not the only means, but probably the most important. Sight conveys the most information, the most detail about the world around us. Think, for example, of the richness of detail in today’s high-definition (HD) or 3D images. Now, to remind us of light’s importance and how useful it is in our lives, the UN has declared 2015 as the International Year of Light.
From Euclid, who first put down the principles of geometric optics in 300 BC, to Alhazen, whose first real theory of light and sight around 1000 AD was so influential in Europe, to Francesco Maurolico who in the 16th century developed a modern theory of sight and the functioning of the eyes – light and sight have long fascinated scientists. Indeed, light is fundamentally linked to the birth of modern science. In 1609–1610, Galileo Galilei was able to perfect the lens and telescope, making the first modern scientific instrument. The “canone occhiale” or “spectacles cannon” – the words at the root of the Italian for telescope – allowed him to see “things never seen beforehand”, as he wrote in his “instant book” Sidereus Nuncius. Thanks to an instrument based on light, he was able to discover the moons of Jupiter and make the Empyrean Heaven a place where change happens, and therefore worthy of investigation by physicists.
Later in the 17th century, Francesco Grimaldi first observed diffraction – soon formalized by Christiaan Huygens in a complete physics theory – and in 1873 Ernst Abbe showed that this limits the detail of what we can see. The resolution of our vision depends on the wavelength of the light or any other wave used for detection, such as sound waves, as in bats, or electromagnetic waves of different wavelengths. So, if we use millimetre-range infrared waves, the image is inevitably less well resolved than with submicrometre visible light. That is why our vision is so good and we can appreciate the splendour of HD images.
For more than a century, physicists have been able to see with finer wavelength “light” – for example, X-rays with wavelengths 100–1000 times shorter – and today, being able to “see” atoms at the nanometre scale, daily life is invaded by “nanotechnology”. Nevertheless, we can peer down to much smaller scales. Just 90 years ago, Louis de Broglie put forward the unimaginable idea that a particle can behave like a wave, with a wavelength inversely proportional to its momentum. This completed the particle–wave duality initiated by Albert Einstein in his annus mirabilis, when he realized that waves behave like particles and introduced the concept of light quanta, the photons.
The High-Luminosity LHC project is already on the starting blocks to be ready 10 years from now
In this way, particle accelerators can generate the finest “light”. The cyclotrons and synchrotrons of the 1950s and 1960s were capable of illuminating entities such as protons, but were limited by diffraction in the femtometre range. Each new, more powerful accelerator joined the race for the finest light, allowing the best resolving power. Most recently, with the LHC, the simple relation λ = h/p tells us that at 1 TeV (the average collision energy of a quark–quark interaction) we can resolve the attometre, or 10–18 m, scale. However, thanks to higher energy in some collisions and to sophisticated experimental techniques, the LHC has shown that quarks are point-like at the level of 5 × 10–20 m, or 50 zeptometres.
But light is only a means, a bridge between reality and our minds, where the image is formed and vision occurs. Indeed the light generated by the LHC would be useless without “eyes” – the LHC detectors that collect the collision events to record the detail illuminated by the light. As with the eyes, the collected information is then transmitted to the mind for image formation. At the LHC, the computers, the physics theory, the brains of the experimentalists and theoretical physicists – all of these form the “mind” where the wonderful images of, for example, the Higgs boson, are formed and, finally, known. Exactly as with sight, some signals (most of them, in fact) are first treated “unconsciously” (by the trigger) and only a selected part is treated consciously on a longer time scale.
Now the LHC is restarting and we will be able to generate light almost as twice as fine, thanks to the 13 TeV collision energy. Moreover, the High-Luminosity LHC project is already on the starting blocks to be ready 10 years from now (see A Luminous future for the LHC). Why high luminosity? Just as in a room where we might ask for more light to investigate finer details and measure the properties of objects more precisely, with the LHC we are planning to increase luminosity by a factor of five (instantaneous) or 10 (integrated) to make more precise measurements and so extend our sight, i.e., the physics reach of the collider and the detectors.
With our accelerators, detectors, computing facilities, physics analysis and theory, we really do reproduce the act of sight, generating the finest light and therefore perceiving a reality that is unimaginable to our normal senses: the frontier of the infinitely small.
By Thibault Damour, Ivan Todorov and Boris Zhilinskii (eds) World Scientific
Hardback: £83
Reflecting the oeuvre of “a man of two cultures: the culture of pure mathematics and the culture of theoretical physics”, this volume is centred around the notion of symmetry and its breaking. Starting with particle physics, the content proceeds to symmetries of matter, defects and crystals. The mathematics of group extensions, non-linear group action, critical orbits and phase transitions is developed along the way. The symmetry principles and general mathematical tools provide unity in the treatment of different topics. The papers and lecture notes are preceded by a lively biography of Louis Michel, and a commentary that relates his selected works both to the physics of his time and to contemporary trends.
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