The ceremony was attended by official delegations from 35 countries, while other events attracted people from CERN and in the surrounding area to listen to talks, hear music, and see science in the streets. At the same time, webcasts took many of the activities to a much wider “internet” audience, who could also participate in the celebrations via social media.
Celebrations will continue in many different places during the rest of the year. To find out more, visit http://cern60.web.cern.ch/.
The official CERN60 ceremony on 29 September featured the European Union Youth Orchestra, directed by Maestro Vladimir Ashkenazy, with 42 musicians covering all of CERN member and observer states.
An address by the president of the CERN Council, Agnieszka Zalewska, marked the culmination of speeches that had been given by official delegates from the UK, France, Switzerland, Italy, Germany and Portugal.
On 29 September, the German federal minister of education and research, Johanna Wanka, was one of the 35 official delegations to sign the guestbook, with Sigurd Lettow, CERN’s director for administration and general infrastructure.
On 19 September, during a week of CERN Council meetings, a symposium celebrated the 60th anniversary of the first Council session, held in October 1954, just one week after the CERN Convention entered into force. Speakers included CERN’s librarian, Jens Vigen, who presented highlights of Council’s history, here with a view of the Council chamber at CERN.
Croatian students of Gymnasium “Fran Galović” Koprivnica were just some of many who sent in images via social media, with the hashtag #MyCERN60, to wish CERN a happy 60th birthday. Through drawings, cakes, parties and more, people around the world contributed in beautiful and heart-warming ways.
On 17 September, a symposium on “60 years of CERN – 60 years of Science for Peace” took place in the Globe of Science and Innovation. It focussed on the human achievements throughout CERN’s history, and the role that the organization has played in promoting international co-operation. Talks included “SESAME: a parallel universe in the Middle East?” by Eliezer Rabinovici, of the Hebrew University in Jerusalem.
The United Nations Orchestra performed a concert at CERN on 19 September to celebrate the 60th anniversary. Under the baton of conductor and artistic director Antoine Marguier, the orchestra accompanied soloist Matteo Fedeli, who, under the patronage of the Permanent Mission of Italy to the United Nations, performed on a Stradivarius violin.
CERN took part in the annual European Researchers’ Night on 26 September with “Pop Science”, in which CERN researchers showcased their work at multiple venues in Geneva and neighbouring France. The event mixed arts, poetry, theatre, music and science, and included shows with liquid nitrogen, CERNLand games for young people and numerous talks and discussions.
The second TEDxCERN event took place on 24 September, with the theme “Forward: Charting the future with science”. Of the many inspirational talks, Jamie Edwards, now 14, received a standing ovation after he spoke about attempting to achieve nuclear fusion in his school lab by colliding the nuclei of hydrogen atoms via inertial electrostatic confinement.
Fifty years after the seminal discovery of CP violation by James Christenson, James Cronin, Val Fitch and René Turlay, Queen Mary University of London held a meeting on 10–11 July to celebrate the anniversary. This stimulating retrospective was attended by around 80 participants, many of whom had been involved in the numerous experimental and theoretical developments in CP-violation physics during the intervening half-century. The primary focus was to review the experimental and phenomenological aspects of CP violation during the past 50 years, but the meeting also included talks on the future of CP-violation experiments with heavy flavours as well as with neutrinos.
The meeting got off to a barnstorming start with talks by Nobel prize laureates Jim Cronin (1980) and Makoto Kobayashi (2008). Cronin explained that since René Turlay had sadly passed away in 2002, while Val Fitch was no longer able to travel and contact with Jim Christenson appeared to have been lost, he alone of the original team was available to attend such meetings. He carefully outlined the historical context in neutral-kaon physics surrounding the discovery of CP violation at Brookhaven in 1964, giving significant credit to Robert Adair, whose earlier experiment had discovered “anomalous regeneration of K0L mesons” in 1963. This in turn had stimulated Fitch to suggest to Cronin that the latter’s existing apparatus might be used to repeat and improve upon that measurement with 10 times the sensitivity. A search for CP violation in K0 decays to two charged pions would be an additional test that could be made as a by-product of the new experiment.
The proposal was made in 1963 and the experiment commenced within three weeks. Illustrating his talk with photographs of the original laboratory notebooks kept by the team, Cronin explained that it was Turlay alone who performed the analysis for the CP-violation signal, and found a signal corresponding to 40 two-pion K0L decays by Christmas 1963. This result implied that CP violation was manifest in the neutral-kaon system, corresponding, for example, to an admixture of the CP = +1 component in the long-lived K0 at the level of 2.3 × 10–3 – a result later confirmed by other experiments.
Cronin continued by reviewing the later experimental work in CP-violation physics with neutral kaons, confirming and building upon the original discovery, and culminating in the unequivocal demonstration, almost 40 years later, of direct CP violation in the kaon system. His talk stimulated several questions. One participant commented that the time from submission of the seminal paper to publication was very short. Another asked if there had been any expectation or indication of a CP-violation signal before the experiment. Cronin responded in the negative: “We did not even think CP violation was the most important thing – we really wanted to measure K0S regeneration.” A former student of Cronin commented that at the time he was “having lectures from these guys”, and that he “could tell that something exciting was going on behind the scenes”.
Towards a theory
The second talk was by Kobayashi, who together with Toshihide Maskawa had shown in 1973 how to accommodate CP violation into the gauge theory of electroweak interactions, albeit necessitating their bold suggestion of a third family of quarks – insight for which they were to receive the Nobel prize in 2008. Kobayashi carefully outlined the context in which his decisive work with Maskawa on CP violation was performed. He had entered graduate school in 1970 at Nagoya, where the theoretical physics group was led by Shoichi Sakata, and where Maskawa had completed his PhD in 1967. Kobayashi explained how their theoretical ideas had been influenced deeply by Sakata’s work, especially by his 1956 model of hadrons. This was a forerunner to the quark model that, in particular, stimulated the study of the SU(3) group in the context of particle physics. Moreover, a paper by Sakata together with Ziro Maki and Masami Nakagawa in 1962 had included a theory describing mixing in the lepton sector using a 2 × 2 matrix with a single mixing angle.
Maskawa had moved to Kyoto in 1970 and Kobayashi followed him there in 1972, at which point they started to work together on trying to incorporate CP violation into the recently formulated gauge theory of electroweak interactions. They quickly realized that it would not be possible to achieve this goal with only four quarks, and concluded that extra particles would be needed. Their paper enumerated several possibilities, including the six-quark model with their 3 × 3 mixing matrix, which would turn out to be correct. This work, as Kobayshi pointed out, “only took a couple of months”.
Two talks followed on the experimental search for CP-violating phenomena with neutral kaons – past and future – by Marco Sozzi of the University of Pisa and Taku Yamanaka of Osaka University. The search for direct CP violation had needed measurements of K0L decaying to two π0s. This was dubbed the “decay where nothing goes in and nothing comes out”, but successive experiments succeeded in studying it with staged experimental innovations. Between the first observation of CP violation and the eventual demonstration of direct CP violation in neutral kaons, the number of K0 decays observed increased by 5–6 orders of magnitude as a result of technological innovations. Much was made of the long drawn-out history of measurements of Re(ε’/ε) – the observable manifestation of direct CP violation in neutral kaons – with apparent fluctuations (albeit within experimental uncertainties) in its value throughout two generations of experiments on both sides of the Atlantic, before it settled down eventually to its current value of (1.65±0.26) × 10–3. One participant asked what value of η – Wolfenstein’s CP-violating imaginary parameter in the Cabibbo–Kobayashi–Maskawa (CKM) matrix – does the measured value of ε’ correspond to? Sozzi responded that the cancellations in the calculation of ε’ in terms of η are so complete that it is not possible to make such a one-to-one correspondence.
In considering the legacy of the neutral-kaon experiments, Cronin commented that although a great deal of work had been done during the years to measure the values of the elements of the CKM matrix, it was still a great mystery as to why their values are what they are, and he asked whether theory had left the field “in trouble” over this. However, Yamanaka could “only share his frustration”. The baton for CP-violation experiments with kaons now passes to the K0TO (K0 to Tokai) experiment at the Japan Proton Accelerator Research Complex (J-PARC), and the NA62 experiment at CERN.
The meeting moved on next to the B factories, with two historical talks by Jonathan Dorfan, now of the Okinawa Institute of Science and Technology, and Masanori Yamauchi of KEK, respectively, on the PEP-II storage rings at SLAC and the KEK-B collider. The large mixing among neutral B mesons and their relatively long lifetimes offered the possibility to observe large CP violation in their decays, but it was necessary to produce them in motion to allow their decay times to be resolved. The large cross-section in the region of the Υ(4S) made it the ideal production environment, but symmetric collisions would have implied near-stationary B mesons. Pier Oddone, together with Ikaros Bigi and Tony Sanda, proposed a solution in 1987 by suggesting the production of boosted neutral B mesons using asymmetric pairs of e+ and e− beams tuned to the Υ(4S) resonance. This approach has been vindicated by the success of the B factories in comparison with competing ideas, such as fixed-target production by a hadronic beam, for example, at the HERA-B project.
These talks thoroughly reviewed many interesting details of the beam designs. PEP-II and KEK-B pioneered true “factory running” of colliders, with continuous injection used for the first time in these projects. In the end, PEP-II produced a total integrated luminosity of 557 fb–1 between 1999 and 2008, and KEK-B produced 1000 fb–1 by its shutdown in 2010. PEP-II was built by an innovative collaboration between the Lawrence Berkeley Laboratory, the Lawrence Livermore National Laboratory, and SLAC. Asked if this was a model for the future, Dorfan replied: “The time was right. The [US Department of Energy] let us manage ourselves. There was no messing with our budget by Congress, which was a great advantage. Physicists were very involved. It couldn’t be done now!”
BaBar and Belle
Next came talks on the experiments at the B factories, BaBar and Belle, in which their histories were given a thorough airing. The BaBar collaboration had asked Laurent de Brunhoff for permission to use the name and image of his father’s famous fictional elephant, which was duly given with certain conditions attached. (For example, the elephant can be shown holding something only if he is using his trunk, not his hands or feet.) The collaboration went on to pioneer the technique of blind analysis – not as the first experiment to exploit it, but the first to make it standard throughout its analyses. As David Hitlin of the California Institute of Technology, the first spokesperson of BaBar, recalled in his talk, one collaborator had insisted early on that “we don’t need a blind analysis because we know the answer already,” which had convinced Hitlin of the need for it.
The presentations gave a virtual tour of BaBar’s and Belle’s CP-violating and T-violating measurements with B mesons, probes of new physics, tests of penguin amplitudes, neutral-meson mixing with charm, and tests of CP violation in tau decays. Both experiments proved spectacularly that the CKM description of CP violation in the Standard Model is correct. In question time, one collaboration member reported a conversation with a journalist at a conference in Tokyo in 2000. “What’s it like to do a blind analysis? – It’s the scariest thing I’ve ever done in my life,” had been the candid response. The meeting then turned its attention to the Tevatron at Fermilab, where precise measurements of Bs oscillations and related observables gave valuable new constraints on the unitarity triangle, and again provided further detailed confirmation of the Standard Model.
Gilad Perez of the Weizmann Institute then gave a theoretical talk outlining how the physics of the top quark could offer new insights into the flavour problem in the future, especially at the LHC, with unique opportunities for flavour-tagging in top decays. The extremely large mass of the top quark makes it the only quark to decay before it forms hadrons, and this gives unique access in hadron physics to a decaying quark’s spin, charge and flavour. Another important effect of the top’s large mass is its importance for fine tuning the weak vacuum – had its mass been a mere 3% greater, the weak vacuum would have been unstable and there would have been no weak interaction in the form observed. The ATLAS and CMS experiments at the LHC have already collected more than five million tt- pairs, with many more to come. Semi-leptonic decays of t quarks provide a strong flavour-tagging of the resulting b quarks, making such decays akin to a new type of B factory, barely explored so far.
In an historical overview of the LHCb experiment’s genesis, the first spokesperson, Tatsuya Nakada, now of the École polytechnique fédérale de Lausanne, described how it was born out of the “shotgun marriage” of the three earlier proposals for B physics at the LHC: COBEX – a collider-mode forward-spectrometer concept to exploit the large bb cross-section in high-energy proton–proton collisions; LHB – using a bent crystal for extraction of the beam halo for a fixed-target B experiment; and GAJET – using the gas-jet target concept. The LHC Committee had reviewed the three ideas, and in its wisdom stipulated that there should be a collider-mode experiment, but redesigned under new management to allow the three proto-collaborations to merge into a single entity, which became LHCb. “The first time I think a committee was really clever,” Nakada commented. Approval was not trivial, but the impressive results to date have already vindicated the approach taken. A second talk on LHCb by Steve Playfer of Edinburgh University gave a detailed review of its physics output, where the cleanliness of the signatures has surprised even the participants. CP violation in B-baryon decays is a promise for the future.
There were also presentations on the contributions to CP-violation physics from ATLAS and CMS at the LHC. These experiments cannot measure CP violation in purely hadronic B decays because they do not have the required particle identification to reconstruct the exclusive final states. However, with the huge cross-sections available at these energies and the experiments’ good lepton-identification capabilities, they are well placed to surpass the B factories in sensitivity to CP violation in final states in which J/ψ particles decay to leptons.
The discovery of CP violation in neutrinos would be the crowning achievement of neutrino-oscillation studies
Further talks reviewed the theoretical and experimental status of CP violation in charm and the prospects for its discovery, as well as future prospects at the planned upgrades to both Belle and LHCb, and also at neutrino facilities. The discovery of CP violation in neutrinos would be the crowning achievement of neutrino-oscillation studies. There were also two detailed reviews of the history of T violation, first in kaon physics and then in B decays.
A final talk by Marco Ciuchini of INFN/Roma Tre University reviewed the theoretical implications and future perspectives on CP violation. Again, Cronin wondered why the community is not yet in a position to understand the spectra of fermion masses and mixings, including CP violation. The speaker responded that “this is the hardest problem”. One questioner asked if a deviation from the Standard Model were to be observed with the upgraded LHCb or Belle II, thereby indicating some new physics in virtual-loop processes, what energy machine would be needed to observe such physics directly? The answer, said Ciuchini, would depend on the details of the new physics.
The conference dinner took place at the Law Society in the City of London, in grand surroundings appropriate for a 50th anniversary. During the past six years, BaBar and Belle have been collaborating on a grand review of Physics at the B Factories, and the occasion was used to announce the completion of this monumental tome. It was also a fitting opportunity to present complimentary copies to Cronin and Kobayashi, in honour of their personal contributions to the current understanding of CP violation.
One of my most memorable experiences of CERN is from an early morning in the summer of 1966. I drove to CERN with my two small children, one and three years of age, to fetch their dad who had been on a night shift – there were no guards at the entrance in those days. I found him outside the experimental hall being interviewed by a friendly looking gentleman, who after greeting us continued asking questions and taking notes. The gentleman, as I found out afterwards, was the director-general of CERN, Bernard Gregory. This was for me an inspiring and instructive experience. Since then, CERN has grown a great deal, and attracts so many more people that the probability of a young visiting PhD student being interviewed alone by the director-general must not be so large. For me, there are other exciting new features of CERN these days, such as encountering crowds of enthusiastic young people from across the world.
The young CERN has now turned 60, its official foundation being on 29 September 1954. Its creation was a unique act, based on an unprecedented common effort by a number of distinguished scientists from several countries, not only from Europe but also from the US, among them Robert Oppenheimer and Isidor Rabi. We are all impressed by their dedication and commitment, and are grateful to them for the creation of this organization for basic research in science for peace. Since its creation, CERN has served as a “standard model” for several other international scientific organizations.
However, while CERN has just celebrated its 60th anniversary, there is one part of it that is a little older. The CERN “Group of Theoretical Studies” was created through a resolution passed by the CERN Interim Council in Amsterdam in May 1952. It was possible to form this group very quickly and for it to start work, in Copenhagen, even before the decision had been made as to where CERN would be located. Copenhagen had already been a world centre for theoretical physics for several decades. It was clear that CERN Theory would thrive there, owing to the presence of the great and incredibly influential theoretical physicist Niels Bohr, and his competent local staff. Victor Weisskopf, who was director-general of CERN in the years 1960–1964, knew Bohr well, and used to refer to him as the greatest founder of CERN. CERN Theory in Copenhagen was a lively place, and attracted many distinguished international scientists.
The CERN Annual Report for 1955 informs us that: “The Theoretical Study Division is located in the Theoretical Physics Institute, University of Copenhagen. The work of the Division has proceeded according to the programme fixed during the interim period and includes: a) scientific research on fundamental problems of nuclear physics, including theoretical problems related to the focusing of ion beams in high energy accelerators; b) training of young theoretical physicists; c) development of active co-operation with the laboratories of Liverpool and Uppsala, whose machines and equipment have been placed at the disposal of CERN.” This was what CERN’s “founding fathers” had in mind that the theorists should be doing. But, of course, except for b, that was not what the theorists actually did.
Theory went on to flourish at CERN, and the subsequent history of the Theory Division deserves a book of its own
The 1955 CERN Annual Report also informs us that the Theoretical Study Division in Copenhagen had two full-time senior staff members: Gunnar Källén and Ben R Mottelson (who was to receive the 1975 Nobel Prize in Physics). Note that these “leaders”, both born in 1926, were at the time below the age of 30. This was a general feature of the young CERN – even the accelerators were built by people who many of us would now consider as “youngsters”.
CERN Theory was expected to move gradually to Geneva. However, this took in total about five years, until 1 October 1957, when the Theory Group in Copenhagen was officially closed. The theorists who came to Geneva had their offices first at the University of Geneva, then in barracks at Geneva Airport, until they moved to the current CERN site in Meyrin. Theory went on to flourish at CERN, and the subsequent history of the Theory Division deserves a book of its own.
In 1971, I became the first female fellow of the CERN Theory Division, in 1982 the first female member of CERN’s Scientific Policy Committee, and in 1988 this committee’s first female “old boy”. Later, in the years 1998–2004, I was the adviser on member states to CERN’s director-general. I have enjoyed CERN’s international atmosphere enormously, which has given me ample opportunity to meet and talk with inspiring physicists from across the world. I also feel fortunate to have lived in a period when the amount of information revealed about the nature of the elementary constituents of matter and their interactions has been mind-boggling. CERN has been an important contributor in this respect. Who could have imagined that we would arrive at the Standard Model so “soon” – a highly successful theory of weak, electromagnetic and strong interactions?
In 2004, during the mandate of Robert Aymar as director-general, the CERN Theory Division turned into the Theory Unit, under the CERN Physics Department. Does this imply that CERN wishes to guide the theorists to work on the “focusing of ion beams”, and machines as well as equipment, as envisaged by the founding fathers in 1952? Fortunately, during my visits to CERN since, I have seen no such trend. Long live theory at CERN.
This year sees the 50th anniversary not only of the proposal of quarks, but also of what is arguably one of the most groundbreaking theoretical findings in physics: Bell’s theorem (Bell 1964).
To celebrate the theorem and the work of the Irish physicist John Stewart Bell, who was on leave from CERN when he wrote his seminal paper, the university of Vienna held the conference Quantum [Un] Speakables II on 19–22 June. Distinguished invited specialists in the question of non-locality brought up by Bell’s theorem discussed the impacts of the theorem and the future of scientific investigations, together with 400 participants.
John Clauser, who was the first to investigate Bell’s theorem experimentally, mentioned the difficulties he had in acquiring money for his experiments. The breakthrough did not come until the 1980s, when Alain Aspect measured a clear violation of Bell’s proposed inequalities. The philosophical debate between Niels Bohr and Albert Einstein on whether quantum mechanics is complete or not thus seemed also to be settled experimentally – in favour of Bohr. In his talk, Aspect stressed Bell’s ingenious idea to discover the practical implications of what had until then been merely a philosophical debate.
An important further development of Bell’s theorem was the Greenberger– Horne–Zeilinger experiment, in which the entanglement of three instead of only two particles was considered. Another important contribution was achieved with the Kochen–Specker Theorem – next to Bell’s theorem, this is the second important “no-go” theorem for hidden variables in quantum mechanics. In their talks, Daniel Greenberger, Michael Horne and Simon Kochen focused on current questions in their research. Anton Zeilinger, who was co-chair of the conference with Reinhold Bertlmann, stressed the huge impact of Bell’s theorem for technical applications: quantum computing, quantum teleportation and quantum cryptography, which are based on the concept of non-locality as outlined by Bell.
More personal remarks came from Bertlmann, who had worked with Bell as a postdoc at CERN and is the protagonist of his famous paper “Bertlmann’s socks and the nature of reality”, and from Bell’s widow Mary Bell, an accelerator physicist.
The conference title refers to a paper that Bell wrote in 1984, in which he identified what he called “unspeakables”. These are notions that he wanted to eliminate from the vocabulary of physics, because for him they did not qualify as well defined – among them measurement, apparatus and information. However, the title also allowed for another meaning. After 50 years, many important implications of Bell’s theorem have been found, but there is much that follows from the theorem that no one talks or even thinks about yet, and so is still to discover.
By Martina Knoop, Niels Madsen and Richard C Thompson (eds) World Scientific
Hardback: £78
Paperback: £36
E-book: £27
This is a collection of articles on physics with trapped charged particles, by speakers at the Les Houches Winter School in January 2012. They cover all types of physics with charged particles, and are aimed at introducing the basic issues as well as the latest developments in the field. Topics range from detection and cooling techniques for trapped ions to antihydrogen formation and quantum information processing with trapped ions. The level is appropriate for PhD students and early career researchers, or interested parties new to the subject.
By Yasumichi Aoki, Toshihide Maskawa and Koichi Yamawaki (eds) World Scientific
Hardback: £109
E-book: £82
The proceedings of the KMI-GCOE Workshop held in Nagoya in December 2012 contain contributions that are focused mainly on strong coupling gauge theories and the search for theories beyond the Standard Model, as well as new aspects in hot and dense QCD. These include many of the latest, important reports on walking technicolour and related subjects in the general context of conformality, discussions of phenomenological implications with the LHC, as well as theoretical implications of lattice studies.
By V Alan Kostelecký (ed.) World Scientific
Hardback: £76
E-book: £57
The Sixth Meeting on CPT and Lorentz Symmetry held in 2013 focused on tests of these fundamental symmetries and on related theoretical issues, including scenarios for possible violations. Topics covered at the meeting include searches for CPT and Lorentz violations in a range of experiments from atomic, nuclear, and particle decays to high-energy astrophysical observations. Theoretical discussions included physical effects at the level of the Standard Model, general relativity, and beyond, as well as the possible origins and mechanisms for Lorentz and CPT violations.
By Andrew Sessler and Edmund Wilson World Scientific
Hardback: £58
Paperback: £32
E-book: £24
Also available at the CERN bookshop
The first edition of Engines of Discoverywas published seven years ago to wide acclaim. Since then, particle physics has seen the dramatic start up of the LHC and the subsequent discovery of a Higgs boson – a long-awaited missing piece in the Standard Model of particles and their interactions. At the same time, the field of accelerators has seen further developments to push back frontiers in energy, intensity and brightness, together with growth in the use of accelerators in other areas of science, medicine and industry.
In the revised and expanded edition of their book, Sessler and Wilson have aimed to match this growth, in particular through a number of essentially new chapters. These naturally cover the work that is going into developing new machines for fundamental physics, from high-intensity super-beams and factories for neutrino physics, to future high-energy linear colliders, and back to the low energies of rare-isotope facilities and, lowest of all, the production of antihydrogen. However, most of the new chapters focus on applications beyond the confines of particle and nuclear physics, with dedicated chapters on the use of accelerators in isotope production and cancer therapy, industry, national security, energy and the environment. Here, for example, spallation neutron sources have been promoted to merit a chapter of their own.
Last, the authors have brought the future and the young more into focus by directing all of the final chapter, rather than only the last paragraph, “mainly to the young”. Sadly, Andrew Sessler – a visionary leader in the field of accelerator science – died earlier this year, but this book will stand as part of his legacy to future generations. It would have appealed greatly to me when I was young, and the hope is that it will inspire budding young scientists and engineers today, for they are the future of the field.
By Jaan Einasto World Scientific
Hardback: £82
E-book: £61
This book describes the contributions that led to a paradigm shift from the point of view of a scientist from behind the “Iron Curtain”. It describes the problems with the classical view, the attempts to solve them, the difficulties encountered by those solutions, and the conferences where the merits of the new concepts were debated. Amid the science, the story of scientific work in a small country – Estonia – occupied by the Soviet Union, and the tumultuous events that led to its break up, are detailed as well.
By Tom Francke and Vladimir Peskov IGI Global
Hardback: $215
E-book: $215
Research in nuclear physics is inconceivable without the Geiger counter. This gas-filled instrument allows both the presence and the energy of ionizing particles and radiation to be measured. It is now 100 years since Hans Geiger designed the arrangement of its electrodes, but this construction is still used in most current gaseous detectors. In this arrangement, the electrons produced by collision and ionization of the gas atoms are multiplied in the electric field around a thin wire, and the resulting avalanche of electrons delivers an easily detectable signal.
It is only recently that other electrode arrangements for gas counters have been proposed and tested. Besides offering improved properties such as higher counting rates, a certain number of prior conceptions of the electron amplification process had to be revised. These new counters are called “micro-pattern gaseous detectors” because the same lithographic technique is used for their production as is employed in the semiconductor industry.
In their book, Francke and Peskov describe the complete historical development of these counters and discuss the properties and special features of each type. Smaller detectors with a sensitive window of up to 30 × 30 cm2 can be built using the lithographic technique exclusively. These are mainly detectors in a hermetically sealed housing filled with high-pressure gas. Detectors of this type are very stable for many years. For example, the detector of the two-axis diffractometer D20 at the Institut Laue–Langevin has been operating for 14 years. Detectors with larger sized windows work at normal gas pressure and with constant gas current. Their electrodes still have to be assembled precisely by hand.
This handbook should allow every research scientist to choose and produce the best detector possible for a specific application. Numerous pictures with descriptions and many diagrams assist in making a good choice, while the detailed bibliography is particularly helpful.
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