Praxis Archives – Page 134 of 181

Setting the record straight

Dan Brown’s novel Angels and Demons has been enormously popular. A secret brotherhood murders a physicist who managed to produce the first antimatter on Earth. You have surely heard about the book?

I have even read it. Indeed the author has me killed at the very beginning.

CCEint1_12-05 — Walter Oelert, holding a photomultiplier from the ATRAP antihydrogen experiment. Image: Courtesy Forschungszentrum Jülich.

Correct. You die and the antimatter stolen from CERN is used to blackmail the Vatican. CERN does produce antimatter, and the contact of antimatter with ordinary matter results in annihilation where large quantities of energy appear. Aren’t you scared that one day Brown’s scenario may become real?

No, since there is no way to produce and store a large quantity of antimatter.

What does “a large quantity” mean? Are we talking about kilograms?

No, not even about nanograms. I am talking about single atoms. We are not able to produce and store amounts of antimatter that would cause damage of any kind, e.g. that could be used as an explosive, as in the book.

You mean we are not able to now – or ever? Is that a problem of technology or perhaps a result of the laws of physics?

Both. Let us start with technological reasons, which are probably less convincing. Even if somebody could produce lots of antimatter, their main headache would be how to store it. First, they must place it in a vacuum – any other “container” would immediately annihilate, that is disappear! So antimatter must be kept in the very middle of a vacuum by a magnetic field. This is possible, we hope to do it at CERN, but for a few or a few tens of atoms only.

The vacuum must be of the best quality. What we call a vacuum in daily life is far from the ideal. An electric light bulb is not empty but contains a very, very diluted gas. In the CERN “antimatter trap” the gas pressure is 10⁻¹⁷ mbar. This means that on average there are a few tens of thousands of atoms per cubic metre. So even here we have annihilation with “stray” atoms. While it is possible to guard a few hundred antimatter atoms, protecting, say, 1 mg of antimatter from annihilation is practically impossible. And every act of annihilation results in the freeing of a certain amount of energy and degrading of the vacuum. This is a chain reaction.

The technical limit is not a real one. What is impossible today may very well be possible tomorrow. Surely we will learn how to get a better and better vacuum?

I agree that technical arguments may not be convincing. However, in one day CERN produces about 10¹² antiprotons. Renovations, equipment maintenance and upgrading, holidays and other interruptions limit the antiproton production to about 200 days a year. In 50 years of operation at CERN about 10¹⁶ antiprotons would be produced. Even if all of them made anti-atoms, we would arrive at about one millionth of a milligram of antihydrogen – I repeat, in 50 years!

I must add that in the process of antihydrogen production only a tiny percentage of antiprotons make anti-atoms. Once, I calculated that even if all the natural energy resources of our planet – coal, petrol, gas – were used to produce antimatter, it would be enough to drive about 15,000 km by car. This is physics. It does not depend on our technological development.

So we can forget about antimatter as a future energy source?

Of course! Until we find “natural resources” of antimatter (and I would not count on that), the production of antimatter on Earth for energy or, as in the book, for terrorism will never pay off. Much more energy would be used for its production than we could ever get back from annihilation.

**Would you agree that more people learned about CERN from Angels and Demons than from reading scientific information? Is CERN correctly described in Brown’s book?**

This question is a trap so my answer will be diplomatic. In my opinion antimatter, and thus CERN as the only place where we are able to produce it, came into the book by accident. They were just a background. An atomic bomb at the Vatican would have done as well. I do not want to speak on behalf of the author but I have the impression that he wanted to touch on the conflict between science and faith. History shows that sometimes such a conflict has indeed been seen by the church and the scientific community.

And what about CERN? Is CERN really working on a proof that God does not exist – that scientific knowledge is the real god?

A difficult question. For sure there are many people working at CERN who believe in God and their work actually confirms their convictions. There are also those who do not believe in God but believe in science. For them every discovery may be proof that God does not exist, but it is not true that we are working to prove that.

“Soon all gods will be proven to be false idols. Science has now provided answers to almost every question man can ask.” This statement is made in the book by Maximilian Kohler, the [fictional] director-general of CERN. Do you agree?

No, I do not agree. I am sure that science does not contradict faith. One person may say that he studies the laws of nature, another one that he wishes to understand how God initiated or created our world. In my opinion it is the same. Both are doing the same even if they believe in different things. The point of view represented by the head of CERN in the book was very popular in the 1950s and 60s. Not for the first time people believed then that science was close to completion; that technology would save the world. It seemed that building a sufficiently large number of nuclear reactors would solve the energy problem on Earth and so all other problems would disappear. However, people have not become happier and the old problems are still here. We continue to be dependent on nature, which dictates the conditions. I believe that despite more and more knowledge, ultimately it is nature that wins.

Production of the first antimatter atom on Earth brought you great recognition…

Antihydrogen production indeed led to extraordinary publicity. That is probably the reason that this work is considered to be one of 16 very important discoveries made at CERN. In my opinion, and from the scientific point of view, producing the first antihydrogen atom does not deserve such honour; the very production of antihydrogen is not a revolution in physics. It did not bring anything new and we do not care about the production itself but about studies of the antihydrogen atom. This is not at all simple. The first atoms produced moved with almost the speed of light. Indeed, one has to be fast to study such an object. Antihydrogen thus has to be cooled down and locked in a bottle; the slower it is, the better we can watch it. So the real goal is not the production of, but studies of, antimatter. I am sure that at some time physicists will manage to measure its gravitational interactions. That would really be something.

Why are antimatter studies so interesting to the public? Usually it is difficult to sell what physicists do in their large laboratories.

This is not completely true. There are at least a few problems that may be sold easily and in an interesting way even when drinking a good wine at a garden party. One example is relativistic physics – everybody is interested in the fact that the faster you move the younger you are. Another subject is astrophysics or the surrounding universe. It is fascinating to many, probably because we can make certain observations ourselves on a cloudless night. Besides, the astrophysical photographs are so impressive they are printed on the front pages of the daily papers. The curvature of time and space is also an extremely interesting problem. The shortest path between two points is not at all a straight line.

And what about antimatter?

When it comes to particle physics, the problem is complicated. People do not know what we really do. Antimatter is an exception, which is surely due to science-fiction films, where antimatter is very often a subject. Serials gather an audience. If every Monday evening we watch the adventures of the same heroes who conquer the universe in space vessels powered by antimatter, then television characters are quickly treated as one’s own family. In this way antimatter has become a family member.

Is your interest in antimatter also a result of those films?

No. I must admit that I have not seen many of them. Discussions on antimatter began much earlier than when the first episode of Star Trek was produced. The ancient Greeks had already discussed it – albeit under different names. One can read about it in the writings of Aristotle or Plato – writings that are rather philosophical according to our modern views. But 19th-century physicists also wrote about it, not yet knowing about the existence of its components.

I was always fascinated by the idea of symmetry, especially between the world and the antiworld. Does it exist at all? I think that studies of antimatter are so interesting because even in our everyday life we like asymmetry. Just have a look at an ancient Greek temple or a medieval church. But not only buildings – look at a Persian carpet. Only those that are factory-made display a full symmetry; the really expensive ones are handmade. Most appreciated are the very small breaks in symmetry, the subtle “faults” of the carpet weaver.

**It is said that as a young man you considered being an actor. Would you accept the role of Leonard Vetra, the creator of antimatter at CERN, if a film based on Angels and Demons was produced?**

Yes, but only on the condition that they do not take my eye or burn “Illuminati” across my chest with a hot iron. I think that from the acting point of view I would manage – after all Vetra is murdered on the first page of the novel. Does he say anything at all?

Oh yes, but only a little. Exactly four sentences.

Then I am sure I would manage.

High pT Physics at Hadron Colliders

by Dan Green, Cambridge University Press. Hardback ISBN 0521835097, £70 ($110).

Over the past several years, Fermilab physicist Dan Green has developed an excellent course on “High p_T Hadron Collider Physics”. This is now published as a Cambridge monograph that successfully traces the important past and future roles of hadron colliders in testing and probing the limits of the Standard Model for electroweak and strong interactions. In so doing, it provides an accessible and pedagogic introduction to key features of parton-parton collisions in pp or pbar p interactions. It is not, however, an up-to-date survey of the field. Rather, the centre-piece of Green’s book concerns the motivation and experimental strategy for detecting, and subsequently studying, the Higgs scalar particle (the last undetected element of the minimal Standard Model).

Written by an experimentalist, the book is qualitative in nature and can even be enjoyed by final-year undergraduates, although to profit from it formal introductions to particle-physics phenomenology and quantum field theory are essential. (Such courses are fortunately part of most relevant Master’s programmes, and the reader is directed to excellent texts on the subject.) A key feature is the use of dimensional (heuristic) arguments to estimate key production and decay processes in hadron collisions. In addition, and uniquely, the COMPHEP freeware program has been extensively used to back up the dimensional arguments with lowest order computations. Despite some incompatibilities of nomenclature, this innovation is (to the reviewer) extremely successful.

The first chapter presents a concise summary of the Standard Model particles and their couplings, as well as a description of the Higgs mechanism for mass generation of the W and Z bosons. It lays out the key properties of the Higgs boson, and concludes with a list of issues that are not answered by the Standard Model. These issues are (rather superficially) discussed in chapter six, with chapters two to five directed towards experimental and phenomenological issues relevant to the Higgs search.

Chapter two describes, in an extremely accessible way, the detector requirements for identifying key high-p,sub>T parton-parton collision processes and the associated instrumental or irreducible physics-related backgrounds. The treatment of jet energy reconstruction and di-jet mass reconstruction is excellent. Inevitably, given the author’s background in the D0 and CMS experiments at Fermilab, the book leans towards examples of these experiments. In a few cases, some important instrumental innovations are not given adequate space (e.g. the real-time selection of heavy quarks as in the CDF experiment). Students could also have benefited from a description of the relative merits of the CDF and D0 experiments, and of course of the future ATLAS and CMS detectors at CERN’s Large Hadron Collider (LHC).

The third chapter is good reading for any new graduate student. Green introduces key features of collider physics: the central rapidity plateau and its energy dependence; the basic parton-parton collision processes and their kinematics; the main gauge boson and gauge-boson pair production processes; and jet fragmentation. In all cases experimental data (usually not the latest) are used to justify heuristic arguments and COMPHEP calculations. A series of exercises complements the chapter.

Chapters four and five concentrate respectively on the more important results from Fermilab’s Tevatron and on the Higgs search strategy at the LHC experiments (for which chapter four’s material is invaluable as a guide to the experimental backgrounds to be expected from any Higgs signal at the LHC). As a reviewer, I enjoyed the experimental approach of these two chapters and their highly readable nature. However, the extremely important sections on heavy-quark (b and t quark) production were rather incomplete, given the unique measurements at the Tevatron and the important implications for the LHC. While the somewhat arbitrary choice of figures in chapter four (taken in most cases from the experiments) is adequate for lecture notes, it detracts from the book’s quality that an effort was not made to include the latest available data, and to combine data from the CDF and D0 experiments. Chapter five concerns the experimental strategy for detecting and studying the Standard Model Higgs particle at the LHC, and relies heavily on relevant preparatory studies from the ATLAS and CMS experiments.

Finally, the concluding sixth chapter discusses extensions to the Standard Model such as supersymmetry, as well as some of the open questions alluded to in chapter one. While extensions relevant to the LHC physics programme must be discussed, it felt as if this was a hurried addition. Judy Garland’s quotation from The Wizard of Oz: “Toto, I’ve a feeling we’re not in Kansas anymore,” is rather appropriate.

Published at a time when the CDF and D0 experiments are increasing their data samples by more than an order of magnitude, and in advance of the LHC, Green’s book has limited shelf life in its present edition. However, despite some shortcomings, its core is an excellent introduction for any graduate student starting out in experimental hadron-collider physics and can be strongly recommended. Dan Green should be congratulated on the overall quality of his text. Presumably, any new edition beyond 2007 will provide some interesting updates.

From Fields to Strings: Circumnavigating Theoretical Physics (Ian Kogan Memorial Collection)

by Misha Shifman, Arkady Veinshtein and John Wheater (eds), World Scientific. Hardback ISBN 9812389555 (three volume set), £146 ($240).

On the morning of 6 June 2003, Ian Kogan’s heart stopped beating. It was the untimely departure of an outstanding physicist and a warm human being. Ian had an eclectic knowledge of theoretical physics, as one can easily appraise by perusing the list of his publications at the end of the third volume of this memorial collection.

The editors of these three volumes had an excellent idea: the best tribute that could be offered to Ian’s memory was a snapshot of theoretical physics as he left it. The response of the community was overwhelming. The submitted articles and reviews provide a thorough overview of the subjects of current interest in theoretical high-energy physics and all its neighbouring subjects, including mathematics, condensed-matter physics, astrophysics and cosmology. Other subjects of Ian’s interest, not related to physics, will have to be left to a separate collection.

The series starts with some personal recollections from Ian’s family and close friends. It then develops into a closely knit tapestry of subjects including, among many other things, quantum chromodynamics, general field theory, condensed-matter physics, the quantum-hole effect, the state of unification of the fundamental forces, extra dimensions, string theory, black holes, cosmology and plenty of “unorthodox physics” the way Ian liked.

These books provide a good place to become acquainted with many of the new ideas and methods used recently in theoretical physics. It is also a great document for future historians to understand, first hand, what physicists thought of their subject at the turn of the 21st century. There is much to learn and profit from this trilogy. Circumnavigating theoretical physics is indeed fun. It is unfortunate, however, that it had to be gathered in such sad circumstances.

50 Years of Yang-Mills Theory

by Gerardus ‘t Hooft (ed), World Scientific. Hardback ISBN 9812389342, £51 ($84). Paperback ISBN 9812560076, £21 ($34).

Anniversary volumes usually mark a significant birthday of an individual, or perhaps an institution. But this fascinating compilation celebrates the golden jubilee of a theory – namely, the type of non-Abelian quantum gauge field theory first published by Chen Ning Yang and Robert L Mills in 1954, and now established as a central concept in the Standard Model of particle physics. It was a brilliant idea (by the editor, Gerardus ‘t Hooft, I assume) to signal the 50th birthday of Yang-Mills theory by gathering together a wide range of articles by leading experts on many aspects of the subject. The result is a most handsome tribute of both historical and current interest, and a substantial addition to the existing literature.

There are 19 contributions, only two of which have been published elsewhere. They are grouped into 16 sections (“Quantizing Gauge Fields”, “Ghosts for Physicists”, “Renormalization” and so on), each accompanied by brief but illuminating comments from the editor. The style of the contributions ranges from an equation-free essay by Frank Wilczek, to a paper by Raymond Stora on gauge-fixing and Koszul complexes. Somewhere in between lie, for example, François Englert’s review of “Breaking the Symmetry”, and Stephen Adler’s exemplary account of “Anomalies to All Orders”.

One recurrent theme is how unfashionable quantum field theory was in the 1950s and 1960s. As ‘t Hooft puts it: “In 1954, most of those investigators who did still adhere to quantum field theory were either stubborn, or ignorant, or both. In 1967 Faddeev and Popov not only had difficulties getting their work published in Western journals; they found it equally difficult to get their work published in the USSR, because of Landau’s ban on quantized field theories in the leading Soviet journals.” One of the most interesting papers in the book is the 1972 English translation of their 1967 “Kiev Report”, produced via an initiative of Martinus Veltman and Benjamin Lee. It is more detailed than their famous 1967 paper in Physics Letters, and includes a discussion of the gravitational field.

Alvaro De Rújula inimitably brings to life the strong interactions between theorists and experimentalists in the heady days of 1973-1978. He includes a candid snap of Howard Georgi and Sheldon Glashow, circa 1975, which made me wish there were more such shots of the leading players from that era. De Rújula’s is the only contribution to address the experimental situation, despite the editor’s admission that the lasting impact of Yang-Mills theory depended on “numerous meticulous experimental tests and searches”. But, after all, this is a volume celebrating the birthday of a theory.

Many contributors look to the future, as well as the past. These include Alexander Polyakov on “Confinement and Liberation”, Peter Hasenfratz on “Chiral Symmetry and the Lattice”, and Edward Witten on “Gauge/String Duality for Weak Coupling”.

I have only had space enough to (I hope) whet the reader’s appetite. This unusual and elegant festschrift is a treat for theorists – and, as a bonus, you get a full-colour representation on the cover of a 17-instanton solution of the Yang-Mills field equations (designed by the editor).

New exhibition unites people and ideas

The 1st European Research and Innovation Exhibition – the Salon Européen de la Recherche et de l’Innovation – took place in Paris on 3-5 June 2005 under the patronage of Jacques Chirac, president of France. The aim of the exhibition, which is to become an annual event, is to provide a place for players from a broad sector of activities to come together, creating a crossroads where people and ideas from both the public sector and the corporate world can meet. This year, the 130 exhibitors included CERN, the Institut National de Physique Nucléaire et de Physique des Particules (IN2P3) of the Centre National de la Recherche Scientifique (CNRS), and the Dapnia laboratory of the Commissariat á l’Energie Atomique, who together presented a stand showing examples of technology transfer.

CCEint1_11-05 — Jean Audouze, chairman of the Scientific Committee of the European Research and Innovation Exhibition.

Jean Audouze, senior CNRS researcher, is the founder and chairman of the exhibition’s Scientific Committee. Consisting of scientific leaders in the world of research and innovation, this committee is responsible for the programme of events, in particular conferences and round-table discussions. Audouze himself has had a great deal of experience in communicating physics on the highest and broadest levels, as scientific adviser to the president of France (1989-1993) and as director of Paris’s well known science museum, the Palais de la Découverte (1998-2004).

How would you describe the role of research today, in the World Year of Physics?

Research is the driving force behind economic, cultural and social progress. The French government, much as the other European political leaders, has set a goal of devoting 3% of gross domestic product to research and development by 2010. Together, France and Europe are actively preparing for the future to meet the dynamic momentum of countries like the US, China and Japan, with whom competition is already very fierce. According to the OECD [Organization for Economic Co-operation and Development], gross domestic expenditure on research and development by member countries amounted to over $650 billion in 2001. The countries of the European Union contributed about $185 billion of this amount. France spent about $31 billion on research and development, which places it in second position in Europe and fourth worldwide, behind the US, Japan and Germany. Many researchers have started their own companies since 1999. Business incubators are playing a crucial role in the development of new companies, assisted by organizations that provide financing specifically for the creation of innovative companies. The biotechnology and nanotechnology sectors are at present leading in terms of the creation of new businesses

Can you explain the event’s objectives?

The exhibition combined information from fundamental research with its applications. It provided an opportunity for researchers, public and private institutions, universities and the top engineering and business schools in France (les grandes écoles), industrial and commercial companies, R&D departments, incubators, financing organizations, laboratory suppliers, local governments, technology parks (technopoles), research associations and foundations to meet. They could present their activities, develop contacts to encourage professional development, discuss the establishment of new projects, start new partnerships, and negotiate financing for new businesses or research programmes.

CCEint2_11-05 — The Technology Transfer stand of CERN, IN2P3 and Dapnia at the 1st European Research and Innovation Exhibition, held in Paris on 3-5 June 2005.

What was the outcome of the three days?

The final balance is very positive. A total of around 24,000 people attended the event. In addition, the presence of many visitors at the conferences, at the round tables concerning the European research programme and the diffusion of scientific culture in Europe, and at events with the participation of the Nobel laureates in physics has shown the strong interest the public has in scientific topics.

How have politicians reacted to the measures required to maximize the value of scientific research?

The politicians have responded well to the scientists’ needs, indeed a few programmes have received specific financing allocations. They appreciated the creative way the technological developments were presented to the public, and the debates on social impact to arouse awareness of the importance of science for everyday life.

What is the outlook for continuing the dialogue in research, education and industrial promotion?

The perspective for the future is to make this event an annual rendezvous with the participation of other European institutions and national stands.

The World Year of Physics 2005 is an international celebration of physics. Events throughout the year have been highlighting the vitality of physics and its importance in the coming millennium, and have commemorated Einstein’s pioneering contributions in 1905. How can the World Year of Physics bring the excitement and impact of physics, science and research to the public?

I am convinced that the World Year of Physics has been a success in terms of popularizing physics and in conveying enthusiasm for the subject among a large public. In each country, and especially in France, many very exciting events were set up with that goal and have attracted quite big audiences. We astrophysicists have a project to make 2009, the 400th anniversary of the use of the astronomical lens by Galileo, the World Year of Astronomy and Astrophysics.

How can worldwide collaborations and fundamental research laboratories such as CERN, CNRS and Dapnia inspire future generations of scientists?

This inspiration is induced by at least two factors: first, CERN, CNRS and Dapnia are involved in the most exciting aspects of fundamental research, e.g. the very nature of matter and the universe; second, their research programmes are planned for the coming decades: the forthcoming operation of the Large Hadron Collider at CERN and projects like VIRGO (which aims to detect gravitational waves) for CNRS and Dapnia should be very enticing for European newcomers to science.

• The CERN, IN2P3 and Dapnia stand showed examples of technology transfer and was prepared by CERN’s Technology Transfer and Communication groups. In addition, CERN’s Daniel Treille gave a talk “Miroirs brisés, antimatière disparue, mati&egravere cachée: le CERN mène l’enquête”.

Wisdom generation in the Alps: a student’s tale

“Seventy per cent of today’s successful particle physicists have attended this school – which means you have a high chance to be one of them in the future,” says a joyful Egil Lillestøl as he welcomes us to the 2005 European School for High Energy Physics. Instantly more than 100 glasses rise, accompanied by a cheerful applause. We all feel lucky to be here.

CCEsum1_11-05 — The school’s participants, including Sezen Sekmen, who is seated on the left, enjoy a day out in Salzburg.

We are in Kitzbühel, a peaceful town with green and beautiful surroundings in south-west Austria, to witness a curious learning experience and to contribute to its spirit as much as we can. The first evening’s dinner sweeps away any clouds of anxiety we might have, and observations of the first encounters have provided more than 5σ evidence of a great event.

On the first morning, just as rain is refreshing the beauty of the mountains outside, the overhead projector starts to light up the first fields and interactions on the screen. Wilfried Buchmüller from DESY provides us with the most fundamental piece of knowledge we will ever need – the Standard Model itself. The school’s academic programme is like a perfect PhD Student’s Guide to High-Energy Physics, as if to advise “don’t panic” in the wide and diverse realm of this exciting subject, “we will show you the route”.

Our appetite for learning grows as cosmology slowly makes peace with precision in the lectures by Rocky Kolb from Fermilab. He calmly strides through the whole universe, from its brilliant but furious past to its settled and gloomy present, from its simply overwhelming dark side to its modest but comforting light side.

CCEsum4_11-05 — Rocky Kolb, from Fermilab, talks on spontaneous symmetry breaking during his lecture on astrophysics and cosmology.

Then enters Larry McLerran from Brookhaven, who introduces us to the colour glass condensate and the quark-gluon plasma, which happen to be two rather unusual forms of strongly interacting matter. He tells us the ancient tales of the good old days when quarks and gluons used to enjoy their freedom, and how the Relativistic Heavy Ion Collider came along at Brookhaven with the aim of capturing a few memories of such eras. On the other hand, Gerhard Ecker from Vienna draws a somewhat more familiar portrait of strong interactions as he systematically goes through quantum chromodynamics, explaining the usual quarks and gluons, and showing the remarkable detail hidden behind even the simplest approaches in this theory.

The evenings call for our creativity in the discussion sessions (which might also be considered as gentle warnings for us to stay awake during the lectures). Having received our daily lecture notes we are divided into six discussion groups, where we are supposed to make an account of the day’s learning and remove any obscurities in the lectures. Encouraged by the friendly attitudes of our discussion leaders, who are all young and willing theorists, and of the visiting lecturers, any shyness disappears and the first hints of inspiration begin to appear as ideas, questions and comments bravely make their way into the discussions.

It is now Thursday night and the poster session begins, transforming modest students into proud physicists who share the outcomes of their current research with great skill and enthusiasm. As well as discovering new ideas, we also see some different approaches to familiar subjects. For example, as someone who wrote an MSc thesis on the analysis of miniature black holes in the CMS experiment at CERN, I am delighted to come across a poster on a similar study for ATLAS. I discover that our friends from Oxford suffered the same problems we did, and so over discussions we decide to support each other in any future studies of these ruthless objects. Best of all though, is to have the vision that through all of these diverse contributions the goals of physics today can indeed be fulfilled.

The sound of music

But it’s not all work. We also have enough time to answer the irresistible call of the great Alps or to relax in the pleasant atmosphere of the historic town of Kitzbühel. On Saturday we visit Salzburg, the town enchanted by the graceful hand of Mozart.

The second week brings new lectures and new lecturers. After convincing us that Buchmüller’s Standard Model is fine but definitely insufficient, John Ellis from CERN goes on to reveal the vast worlds beyond, which are ruled by brilliant scientific imagination, with of course some rightful emphasis placed on the unavoidable elegance of supersymmetry. His presence is an invaluable gift, especially for me, as my current research happens to be on supersymmetric dark matter. Inspired by his lectures, as devoted experimentalists, we even go on a dangerous quest for dark matter on the nearby Schwarzsee at night.

Later, Robert Fleischer, also from CERN, explains how a nasty complex phase destroyed the beautiful CP symmetry and introduced some excitement into our universe, which would otherwise be less interesting; and how it also caused a few headaches among the physicists trying to explore the rich phenomenology of the Cabibbo-Kobayashi-Maskawa matrix and its unitarity triangles. We then discover some “CP violating terms” in the local organizing committee as two of its members from Vienna, Manfred Jeitler and Laurenz Widhalm, in addition to their efforts to offer us an outstanding experience, present lectures on experimental aspects of B- and K-physics, respectively. Then Manfred Lindner from Munich describes the ghostly neutrinos and the many consequences of their mischievous behaviour, and gives a long list of the global endeavours to discover their nature experimentally.

There are even some lectures not on particle physics. Wolfram Müller from Graz gives instructions on the physics of ski jumping, which seems quite appropriate in Kitzbühel, and Herbert Pietschmann from Vienna shows us our fate on the way to knowledge in his delightful lecture on physics and philosophy.

Meanwhile, the interactions increase, just as predicted by the famous “Summer Student Group Theory”. Although we have grown up under the strict hands of scientific work, the children within us still seek fun and adventure. We make the most of a colourful international community formed without prejudices and borders. The coffee breaks, which seemed a little long in the beginning, now fly swiftly by with cheerful conversations. I feel a significant improvement in my debating skills, especially after all the “SUSY and beyond” discussions with several expert theorist friends.

Grand finale

However, the inescapable end is close. In order to avoid becoming too melancholy and to create a glorious finale, we amalgamate all our creativity in preparing an unforgettable farewell night. This time we are on stage, giving so-called lectures on “serious subjects” (that cannot be mentioned here!), singing, acting and doing all sorts of things to entertain our audience. But finally we have to say difficult goodbyes to all of our friends (yes, we are friends now), and leave the cosy Hotel Kitzhof, where our hosts, through their patience and goodness, have somehow managed to survive our two-week occupation.

I know that all of us share the same feeling of gratitude towards everyone who made this school possible. I am especially indebted, as a student coming from an observer state who had the privilege of being supported through the generosity of CERN. We are greatly thankful for the endless support and kindness we received from Egil Lillestøl (CERN schools director), Danielle Métral (CERN schools secretary), Tatyana Donskova (JINR schools secretary), all the local organizers plus all the other representatives of CERN and JINR who were with us during the school. We have been thoroughly enriched as a result of their sincere efforts. This worthy tradition must continue, as long as physics has new puzzles to offer us and as long as we can respond through willing fresh minds.

CERN and Poland sign agreement

On 29 July, the rector of the AGH University of Science and Technology in Cracow, Ryszard Tadeusiewicz, and CERN’s director-general, Robert Aymar, signed a collaboration agreement relating to the commissioning of the instrumentation and monitoring equipment for the cryogenic system of the Large Hadron Collider (LHC). A team consisting of 12 physicists, engineers and technicians from the AGH University will assist teams at CERN in commissioning the cryogenic system in the tunnel.

CCEnew2_10-05 — Robert Aymar and Ryszard Tadeusiewicz in the LHC tunnel after signing the agreement.

This is the first in a series of agreements that will relate to the commissioning of the LHC’s various systems. From the end of this year until the summer of 2007, CERN will enlist the aid of physicists, engineers and technicians from many different institutes in order to complete the tasks associated with the start-up of the accelerator.

Masterclass spreads the word for physics

The videoconference between centres in different countries created an authentic feeling of international collaboration.

Particle-physics masterclasses began in the UK in 1997, the centenary of J J Thomson’s discovery of the electron. It was then that Ken Long of Imperial College and Roger Barlow of Manchester devised a series of one-day events for 16- to 19-year-old pupils and their teachers. Run by particle physicists at various institutes all over the UK and coordinated by the High Energy Particle Physics Group of the Institute of Physics, each year the programme offers a very popular combination of exciting talks and hands-on experience of the interactive graphical display programs that particle physicists use at CERN. More recently, the concept of the particle-physics masterclasses has been successfully adopted by several institutes in Belgium, Germany and Poland on a regular basis.

The World Year of Physics 2005, commemorating Einstein’s annus mirabilis, was the inspiration for the particle-physics masterclasses to spread even further. It was just enough to mention the idea of a Europe-wide version of this programme for all the members of the European Particle Physics Outreach Group (EPOG) to come on board and try to get institutes in their countries involved. EPOG promotes the outreach activities of particle-physics institutes and laboratories in CERN’s member states and acts as a forum for the exchange of ideas and experiences related to particle-physics outreach. Fifty-eight institutes in 18 countries across Europe, from Athens to Bergen and from Lisbon to Helsinki, participated in the masterclass event, which was centrally coordinated at Bonn University.

The basic idea of the pan-European event was to let the students work as much as possible like real scientists

As with the original masterclasses, the basic idea of the pan-European event was to let the students work as much as possible like real scientists in an authentic environment at a particle-physics institute, not only to feel the excitement of dealing with real data, but also to experience the difficulties of validating the scientific results. After lectures from practising scientists they performed measurements on real data from particle-physics experiments, and at the end of each day, like in an international collaboration, they joined in a videoconference for discussion and combination of the results.

The measurement of the branching ratios of Z boson decays at CERN’s Large Electron-Positron Collider (LEP) was chosen as the main common task at all sites. For this the students had to identify the final states of quark-jets, electron pairs, muon pairs and the notoriously difficult tau pairs from the tracks and signals in various components of LEP detectors. Interactive computer material for this task was available using data from OPAL in the Identifying Particles package from Terry Wyatt at Manchester, or alternatively using DELPHI data in A Keyhole to the Birth of Time by James Gillies and Richard Jacobsson at CERN or in the well known Hands-on-CERN package developed by Erik Johansson of Stockholm.

To simplify students’ access to the unfamiliar world of particle physics, EPOG and the national institutes undertook the immense effort of translating the material into various languages. By the beginning of March, each package was available in at least one of 16 languages, with Hands-on-CERN now covering 14 languages, from Catalan to Slovak. This material, including real data for performing the measurements and several extra teaching and learning packages, lays the basis for regularly performing masterclasses at a European level, and is also of valuable use outside the masterclasses. It is available on the Internet and on a CD that was given to each masterclass participant.

Graph of Students Feedback — The students’ feeling that they had learned more about the organization of scientific research contributed significantly to a general increase in interest in physics. The points and error bars show the average change of interest; responses from “strongly decreased” up to “strongly increased” were possible.

The skills required to become a “particle detective” were taught in the morning lectures at each institute. Since in most countries particle physics is not normally taught at school, the talks had to go all the way from basic explanations to the world of quarks and leptons. “Easy-to-follow explanations of scientific research” was the immediate reaction of one of the students at Berlin. After some brief training by young researchers from the institute, the students made the fascinating discovery that they were indeed able to identify the elementary particles on the event displays themselves, at least in most cases; it was even more fascinating for them to learn that professional scientists cannot be completely sure either on an event-by-event basis that their identification is right. The exercise was in fact usually performed quite quickly: “What next?” was a frequent demand once the Z-decays were measured.

Another innovative idea of the EPOG European Masterclasses was to hold an international videoconference at the end of each day using the same Virtual Room Videoconferencing System (VRVS) technology as practising scientists. CERN’s IT Department and the Slovak group of the Caltech VRVS team provided valuable technical help for the many institutes that had never used this tool before. The link-up was centrally moderated by two inspiring young researchers at CERN: Silvia Schuh from ATLAS, and Dave Barney from CMS (who recently received the 2005 Outreach Prize of the High Energy and Particle Physics Division of the European Physical Society). Using English as a common language, the students discussed why, for instance, classes in Helsinki and Vienna found significantly more taus than those in Innsbruck, Heidelberg, Bonn or Bergen. They then assigned systematic errors derived from the differences and ended up with combined measurements, confirming (happily!) the results from LEP. In addition invited scientists at CERN were ready to answer further questions on topics ranging from antimatter and Big Bang cosmology to the daily life of a CERN researcher.

The videoconferences made the students aware that the masterclasses were taking place in other countries, and created the feeling of an international collaboration of researchers. It was “interesting to learn how scientific information is exchanged around the globe”, according to one of the comments on the feedback questionnaires, which are currently being evaluated by the Leibniz Institute for Science Education (IPN) at the University of Kiel.

How was it for you?

The first results from the evaluation show that, independent of country and gender, some 70% of about 400 female and 900 male students felt strongly or very strongly that they had learned at the masterclasses how scientific research is organized and carried out. More than 81% liked the masterclasses “much” or “very much”, again independent of gender. Moreover, there was significantly higher enthusiasm in Finland, Portugal and the Czech Republic with 96% choosing “much” or “very much”, which can mostly be attributed to particularly interesting lectures and a bigger increase in knowledge of particle physics.

Graph of students feelings — A clear majority of students would like more modern physics – such as particle physics – to feature in their science lessons at school, a response that is somewhat correlated with the perceived difficulty of the masterclass programme.

The impact on the student’s interest showed greater spread between the countries. On average 58% of both male and female students felt that they were generally more interested in physics after the masterclasses, and only 6% were less interested. Again, the masterclasses had a significantly stronger impact in Portugal and Finland, with 86% and 95% of students respectively reporting increased interest. In two countries the female participants benefited especially. While the male participants showed no significant deviation from the average, 78% of the Italian girls and all seven female students in Sweden reported an increased interest in physics. The Swedish girls unanimously marked the highest possible increase in their knowledge of particle physics, and felt more strongly than average that they had learned about the organization of scientific research. For all students both factors correlated very strongly with positive answers to the question on increased general interest in physics (see figure 1). Apart from this, the reactions of the female and male students to the masterclass programme were nearly identical, although in all countries the girls said they thought they knew significantly less about physics than the boys and were significantly less familiar with computers.

Finally, regardless of whether they like their current physics lessons at school, 65% of the students thought that modern physics, like particle physics, should play a bigger part in their science lessons (see figure 2). This question showed the largest variation between the countries. The majority was significantly higher, for example, in Germany, with 75% of the students responding positively, and Portugal with 91%. In Switzerland and Norway, by contrast, not even 30% of the students clearly supported this statement. In the latter two countries more than half of the students found the level of the masterclasses rather difficult, while on average only 19% shared this opinion.

“I got the feeling that I did something which physicists do every day in their experiments, and I felt involved.” This statement from a 17-year-old girl shows that the authentic surroundings and the measurements with real data were indeed able to bring modern physics close to the hearts of young people.

• For more details about the event and materials see http://wyp.teilchenphysik.org. The European Masterclasses were sponsored by the High Energy Physics Board of the European Physical Society and the Bundesministerium für Bildung und Forschung (BMBF), and received organizational help from the German Science-on-Stage Executive Office. The EU has acknowledged the success of the first European Masterclasses by nominating the project leader, Michael Kobel, for a Descartes Prize for Excellence in Science Communication for 2005. The project is now competing with 22 other nominees for up to five Descartes Communication Prizes, to be awarded in December in London.

HELEN network unites Europe and Latin America

After I became director-general of CERN in 1999, I had the chance to meet Juan Antonio Rubio, a well known experimental physicist and former collaborator of Carlo Rubbia and Samuel Ting, who is now the director-general of CIEMAT, Spain. In addition to his other good qualities, Rubio has a deep knowledge of Latin America – her people, schools and traditions. We understood that the Large Hadron Collider (LHC) being built at CERN offered a great opportunity to renew old ties with Latin America and to attract to Europe and CERN a new generation of experimental physicists.

CCEhel1_10-05 — The website for the HELEN project, which was launched on 1 August 2005.

In the past, ties between European and Latin American particle physics had been very strong, involving well known physicists such as Cesar Lattes, José Leite Lopez, Roberto Salmeron and many others. Lately, however, Latin American experimental physicists had turned to the US, and Fermilab in particular, as their main point of contact in particle physics. The US had opened up to them and to their students under the enlightened action of Nobel prize-winners such as Richard Feynman, whose stay in Brazil had an enormous influence on the development of fundamental physics there, and Leon Lederman. On the other hand, theoretical physicists in Latin America had always considered CERN as one of their main poles of interest (together with the International Centre for Theoretical Physics, Trieste) with physicists of the calibre of John Ellis, Alvaro de Rújula and Luis Alvarez Gaumé being particularly friendly to Latin Americans.

CCEhel2_10-05 — Mobility of physicists going from Latin America to Europe during the three years of the HELEN project. Total number of fellowships is 322; number of months is 1002.

The first step towards rebuilding the relationship with Latin America was launching a biannual CERN-Latin American school of physics. I discussed the matter with Egil Lillestol at the 1999 European School of High-Energy Physics in Bratislava, and we concluded that the conditions were right to go ahead. The first Latin American school, modelled on CERN’s long-standing European School of High Energy Physics, was held two years later in Itacuruça, Brazil. It was a clear success, demonstrating the interest of the younger Latin American generation in European physics, CERN and the LHC.

CCEhel3_10-05 — Movement in the other direction, with in total 94 fellowships and 164.5 months.

At the same school, I also saw first-hand a strong interest going in the other direction, with European physicists curious about the Pierre Auger Observatory, the ultra-high-energy cosmic-ray detector being built in Argentina. Indeed, as I learned at Itacuruça, the sum of contributions to the project from CERN member states was already larger than the contribution made by the US via the Department of Energy, a nation historically considered the main partner of Latin American countries.

The first Latin American School of High Energy Physics marked the beginning of a new collaboration, but during the following years the problem was how to keep the collaboration going, in view of the difficulties that were arising from financing the LHC. In late summer 2003, Philippe Busquin, the EU commissioner for research whom I had asked for support, pointed out that a programme from the EU Commission, América Latina – Formación Académica (ALFA), was the natural framework for stabilizing relations between CERN and Latin America, by taking advantage of the potential for training young physicists that the LHC offered.

Rubio and I quickly got the message and started to prepare an application to ALFA. Fortunately, another lucky circumstance made the enterprise possible. Verónica Riquer, a former student of Marcos Moshinsky (a well known nuclear theorist from Universidad Nacional Autónoma de México, UNAM), was a postdoctoral fellow in CERN’s theory division. A good friend of Rubio, Riquer somehow knows everybody doing physics anywhere in Latin America, and even has a clear idea of what they are actually doing.

Riquer enthusiastically adopted the project that was going to have a big impact on her for the next few years (“HELEN nos va matar” she warned me in the difficult periods – “HELEN is going to kill us!”). Indeed, she proved the crucial person to connect with high-energy physics groups in Latin America, to get them involved in the hard work of preparing a valid application to the (notoriously difficult) EU Commission and, finally, to convince so many people on a different continent to persuade 22 rectors to sign an agreement with the EU at very short notice. Eventually, the full application was finished during the night of 29 April 2004, and taken by hand to Brussels the following morning, complying exactly with the deadline of 30 April 2004. Riquer left CERN to see her family in Mexico, and Rubio and I could relax. The High Energy Physics Latin-American-European Network (HELEN) now existed.

HELEN is a big project. Over three years, it will involve stays in Europe totalling 1002 months (70% at CERN) for students and young researchers from 22 institutions across eight countries in Latin America, and stays in Latin America totalling 164 months for physicists from seven European countries (about 50% at the Pierre Auger Observatory). In addition, some 15% of the budget is dedicated to visits from professors in the network, to give seminars, oversee students and start new collaborations. Each institution has one reference person (the “interlocutor”), among them Arnulfo Zepeda in Mexico, Alberto Santoro in Brazil and Teresa Dova in Argentina. All in all, we expect a whole new generation of Latin American physicists to be trained in particle physics at the most advanced facilities in the world, and to establish new ties with their European peers.

On a happy day last February, we received the news that HELEN had been approved and that we could start discussing the practical implementation of the contract. In fact, at the time I was in Mexico, spending two months at the Centro de Investigación y Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV). There, I could see first-hand the enthusiasm that HELEN was raising in Latin America. In the few months since HELEN’s approval, we have had to refine the project and make it suitable for a contract between the EU and the Università di Roma “La Sapienza”, the coordinating institution of HELEN. However, at last, the contract was signed on 28 July and the project officially started on 1 August.

When physics needs the public

Decision-making in high-energy elementary particle-physics research is usually highly technical, sometimes political, and often very passionate. And now, in the 21st century, scientists have come to realize that the public not only has the right to know what science we do, but should also be involved in many decisions of that scientific work. This is precisely what the particle-physics community has set out to accomplish with the design process and creation of the world’s next big particle accelerator.

CCEvie1_10-05 — Image: Fermilab Visual Media Services.

Outside of space exploration, it is sometimes assumed that large populations are not interested in science, but the International Linear Collider (ILC) is an accelerator that will collide particles of matter and antimatter to help solve some of the true mysteries of the quantum universe. So how can the public be involved in the design of such a complex facility?

In August, I was among the nearly 700 participants in the 2005 International Linear Collider Physics and Detector Workshop held in Snowmass, Colorado. A number of my colleagues around the world engaged in the global design effort have been studying the technical issues and understanding the limitations of the proposed facility for some years. Now, in addition to the physics, a communications group is focusing on how this facility will affect the public when completed, and how physicists should communicate our work to decision-makers and the public.

In many scientific disciplines, the research community often communicates to the public on laboratory experiments by reporting the benefits after the designs are completed, during the building of the apparatus (if any), and after the research results are assembled. For the ILC project, communication was a high priority from the very beginning. At the ILC workshop, Judy Jackson of the Fermilab Office of Public Affairs and a member of the ILC Communication Group invited Douglas Sarno, head of The Perspectives Group, Inc. of Alexandria, Virginia, to lead a seminar on the public-participation process.

At the seminar, Sarno instructed us on elements of the process: identify members of the public and the “stakeholders”; examine and include the public values; and seek input from all sides when issues arise. He helped us recognize the benefits of this effort in general, and showed how real participation in the process leads to decisions.

There can be a range of participation in this process, from minimal participation where the public is informed only of the general scientific goals and information, to the other end of the spectrum where the final decision on the project implementation is in the hands of the public. The former can be accomplished by reading materials, websites, public lectures and personal contacts, while the latter might additionally require ballots, elections, citizen referendums or chief-executive initiatives. For the ILC, the specifics of the ideal public-participation process lie somewhere in between, and of course input from the public is required to find the right level. When we think about access to materials, land use, ecology and economic impacts due to the resources that are required, large scientific projects are never isolated from the public.

I am now convinced that the ILC project will benefit from a high level of public participation. Because of the very long tradition of international participation in particle-physics research, and the international character of this project, the public-participation process should include all the countries and regions contributing to the project, taking into account the role of local communities. I believe our discussion helped those participating in this seminar gain a broader view of how the decisions concerning the ILC might include a public perspective, independent of region.

However, the ILC is a complex facility and the science that motivates the need for this facility is equally complex, which of course means that decisions are multifaceted and interwoven primarily with physics issues. Nevertheless, a host of other considerations and opportunities will include resource and design issues, communication, organization, a construction timeframe, the world-community effort and – usually before any actions – a decision. The level at which the public is included in this decision process could also be viewed as a complex question.

My experience in public communication leads me to conclude that involving the public early in the design and description of our scientific research, and continuing that involvement, is crucial to an effective partnership between the public and the scientific proponents of our research. Although it is a noble goal to teach particle physics to the public and government leaders, this may not always be necessary. It is important to convey the excitement and the impact of the ILC project on society, and to earnestly listen to the response of policy-makers and members of the public about all of our science. It is vital to gain and sustain the trust of the public, so that the inevitable changes in this research project will be embraced and perhaps even understood as a regular component of fundamental research.

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