Praxis Archives – Page 179 of 181

The incomprehensible is always fresh

As we worry about how we will mark the passage of the millennium and whether its technology will survive that incremental year, fundamental physics has already embarked on its assault on the 21st century. Caught up in the jostle, it is hard to perceive this acceleration. But look back 100 years and it is clear how the prospect of the 20th century provided incentive right across the cultural spectrum.

The work of poverty-stricken artists who were humiliated by the drudgery of unrecognized creativity now trades for fortunes. Fresh influences that were to fire the popular music of the 20th century blazed only in the confines of the ghetto.

Physics too was poised on a launchpad. The decade spanning the 19th and 20th centuries brought a chain reaction of discovery: X-rays, radioactivity, the electron, quantum theory, special relativity…Before the century was much older, a full theory of relativity and the interpretation of empirical quantum theory in terms of quantum mechanics had revolutionized our understanding of the universe.

Rather than having been assimilated into the collective consciousness, these two monuments of human intellect quantum mechanics and relativity still remain obstacles to the public understanding of science. In his introduction to the first edition of his masterpiece The Principles of Quantum Mechanics, Paul Dirac said: “The methods of progress of theoretical physics have undergone a vast change during the present century [he wrote in 1930!]. The classical tradition has been to consider the world to be an association of observable objects (particles, fluids, etc) moving about according to definite laws of force, so that one could form a mental picture in space and time of the whole scheme…It has become increasingly evident…that nature works on a different plan. Her fundamental laws do not govern the world as it appears in our mental picture in any very direct way, but instead they control a substratum of which we cannot form a mental picture without introducing irrelevancies.”

Dirac was trying to encourage students who were about to embark on a difficult but rewarding book, warning them that they should loosen the straps on their 19th-century imagery of springs and gear-wheels and prepare to accept an unfamiliar “impressionist” physics.

Some 70 years later, many generations of physicists have learned to handle relativity and quantum mechanics in their sleep, but these concepts remain a foreign language for the uninitiated.

“The new theories, ” wrote Dirac, “if one looks apart from their mathematical setting, are built up from physical concepts which cannot be explained in terms of things previously known…which cannot even be explained adequately in words at all. Like the fundamental concepts which everyone must learn on their arrival into the world, the newer concepts of physics can be mastered only by long familiarity with their properties and uses.”

For the 21st century, physicists are venturing into even deeper conceptual water, painting ambitious new pictures that even Dirac would have shunned. Abandoning the “classical” concept of point particles in favour of two dimensional strings in many-dimensional spaces, new developments suggest that some of the mysteries of quarks and gluons could be inferred from quantum theories of gravity cast in many more dimensions than once was ever thought necessary. The microworld could be a hologram of an otherwise invisible structure of a larger universe.

Superstrings

Recent CERN Courier articles on superstrings by Gabriele Veneziano and Yaron Oz have pointed out how we could have been blindfolded by living in a four-dimensional spacetime lesion embedded in a much larger, but ironically indiscernible, scheme. Our limited experience might not be that of most of the rest of the universe, and another Copernican revolution might be round the corner.

These ambitious theories are not yet ready for any textbooks, but something will surely emerge from all of this intellectual industry. Such a reappraisal of our understanding could go on to parallel Planck’s introduction of the quantum concept 100 years ago.

If these new theories do bear fruit, then the problems underlined by Dirac 70 years ago will have been amplified. The preface to the ultimate 21st-century textbook The Principles of Superstrings will have to encourage students even more than Dirac did, and the public, blinkered by living in three dimensions, let alone four, could be even more in the dark and seek easier intellectual comfort.

The 21st-century public could find physics not to its taste unless a major effort goes into making the subject palatable. For physics, a key problem is to accomplish this while retaining the confidence and credibility of the scientists. Paraphrasing what can ultimately only be expressed with mathematical precision can attract heavy dogmatic firepower. Researchers accustomed to peer review frequently get hold of the wrong end of the stick when confronted with a popular market.

A successful play now running in London has shown that physics, given the right treatment, can have popular appeal. However, science communication ultimately has to come from scientists. Where Carl Sagan and Stephen Hawking whetted the public appetite for the incomprehensible, others have followed. With the prospect of fresh conceptual horizons, a new door is open.

Detectors for Particle Radiation by Konrad Kleinknecht

Cambridge University Press 0521 64854 8 (pbk $19.95/$34.95), 0 521 64032 6 (hbk £52.50/$80).

The second edition of this popular text has been updated with the inclusion of recent detector developments and a presentation of modern experimental facilities.

The excellent introduction provides a thorough discussion of the physics principles of detectors, including, for example, such modern treatments as the Photoabsorption Model for the energy loss. This recommendable approach provides the reader with a basis for understanding and evaluating detector behaviour.

The subsequent chapters focus in turn on different types of measurement (position, time, particle identification, momentum, energy). Within each broad topic the full range of the relevant detectors is analysed. The text is complete, yet compact and authoritative. A wealth of equations guides the reader to an analytical understanding of detectors.

One important subject energy measurement would merit a more extensive discussion. A more systematic analysis of the various contributions to the energy resolution would demonstrate that these detectors too can be understood from first principles.

One of the big successes of particle physics detectors is their increasing range of applications in other areas. The description of these applications, although short and less complete than this success merits, should be applauded.

The book is illustrated throughout with instructive diagrams of fine quality. Only the admittedly difficult illustration of large detector facilities will probably leave the novice unsatisfied. A complete list of references covering approximately 30 years of research and development provides ready access to the source literature.

This volume will serve the apprentice experimentalist as an attractive introduction and the seasoned physicist as a fine reference. The publishers should be congratulated for issuing this text in paperback.

Conceptual Foundations of Quantum Field Theory

edited by Tian Yu Cao, Cambridge University Press 0 521 63152 1 (hbk £60/$100).

books1_5-99 — Conceptual Foundations of Quantum Field Theory, edited by Tian Yu Cao, Cambridge University Press 0 521 63152 1 (hbk £60/$100).

Tian Yu Cao’s book Conceptual Developments of 20th Century Field Theories, published in 1997, was hailed in many quarters as a masterpiece. The same careful thinking is evident in this book, the result of a conference held at Boston University in 1996.

Boston (particularly Harvard) has long been a cradle of field theory, even during the dark years when the subject was not fashionable, and many key figures attended the event. The idea was for leading field theorists, philosophers and historians to present their insights and views. Participants included Sidney Coleman, David Gross, Sheldon Glashow, Steven Weinberg and Arthur Wightman.

All of these figures also participated in a lively concluding round-table discussion that was moderated by Stanley Deser. The following extract from this discussion underlines the scholarship and entertainment that the meeting provided.

Gross: Actually, I wanted to answer [the] question about what question I would ask God…There are two answers…The first is a kind of joke. I’d paraphrase Gertrude Stein and ask “What’s the question?’, because in some sense that’s really the hardest thing in physics: to ask the right question. In explaining to me the question, He would have to explain all the answers I would like to know.

Deser: He’s subtle. We don’t know what He would say.

Gross: The other question is one that from the point of view of particle physics seems to be the most mysterious…that is, “Why is the cosmological constant zero or so small?”

Weinberg: I think we all always keep raising the same question, which is why things are the way they are.

Deser: Sure, but there are some things which are more “the way they are” than others. And it’s not clear to me why the cosmological constant is picked on specifically as being

Weinberg: It’s a lot of orders of magnitude.

Deser: No, I understand that.

Coleman: 120 orders of magnitude between the rough order of magnitude and the experimental observation.

Deser: That should tell you that it can’t be the fundamental problem. But anyway, that would take longer to discuss. Shelly, what would you like to ask God, or do you know all the answers?

Glashow: I’m working at that…One question: “Why is the top quark so heavy?”

Deser: That’s a good question. You don’t care about the tau lepton?

Weinberg: Yeah, I would have said, you know, that’s the easy one, because that’s the mass you would expect.

Coleman: Why are the others so light?

Gross: Why is the neutrino so light?

Glashow: Yeah, well, you start off with the easy questions, see.

Weinberg: Why is the electron so light? That’s really hard. I mean, the electron is the mysterious particle, not the top quark.

Deser: Anyway, why is this difference of emphasis important?

Weinberg: Well, it does direct the way you think. I mean, some people think you have to give the top quark new kinds of interactions which are different from the other particles. And other people think you have to invent new symmetries that keep the light quarks light. I’m not sure, obviously, which is right, but there is a difference.

Glashow: Steve, we’re asking the same question: “Why is there this little, curious factor of 105 between the mass of the lightest particle and the mass of the heavier particle?”

Weinberg: Yeah, that’s the right one to ask. And it really is an amazing thing.

Deser: And you have no leptonic questions?

Weinberg: Same question.

Historic hardware

news4_4-99 — A particle’s-eye view through the central detector of the UA1 experiment a feature of the new Hunting the Bosons exhibition at CERN’s Microcosm exhibition centre.

In 1983 the big UA1 and UA2 experiments at CERN revealed the long-awaited W and Z particles, the carriers of the weak force. UA1, UA2 and much of CERN’s antiproton infrastructure are no more, but CERN’s Microcosm exhibition centre is preserving some of this historic hardware and transforming it into the focus of a new Hunting the Bosons exhibition.

Pakistan creates national centre for physics

news1_3-99 — Distinguished theorist Riazuddin is director of the new National Centre for Physics (NCP) at Quaid-i-Azam University, Islamabad.

To promote research in physics and strengthen university capability in Pakistan, a National Centre for Physics (NCP) has been established at Quaid-i-Azam University, Islamabad. The director is distinguished theorist Riazuddin and the scientific activities formally began with a one-day symposium on 28 January.

The NCP will try to attract world-class physicists to the Centre throughout the year. Its basic mode of operation will be based on distinguished visiting scholars for periods ranging from a week up to a year.

The NCP will be a permanent focus for workshops, colleges, schools, conferences and seminars covering physics, mathematics and related subjects, and will encourage joint efforts in the relevant departments, institutions, and organizations in Pakistan.

The NCP will also enter into collaborative arrangements with institutions abroad, like CERN and the Abdus Salam International Centre for Theoretical Physics in Trieste.

The strong influence of the late Abdus Salam endowed Pakistan with a distinguished tradition in theoretical physics, and many Pakistani theorists hold important positions in overseas universities and research centres. Recently this tradition has extended to cover also the experimental sector, where Pakistani physicists are involved in the CMS experiment for CERN’s LHC proton collider.

The NCP will also try to use effectively expatriate Pakistani physicists by appointing them as “reverse” associates to enable them to spend some time every year at the Centre.

The Centre is also a natural development of the International Nathiagali Summer College, established in 1976 at the suggestion of Salam and which has been held annually ever since. The twin topics of this year’s school are CERN’s LHC collider and its research programme, and Non-Conventional Energy Resources.

NCP Director Riazuddin took his first research steps under Abdus Salam at Lahore and in the UK, obtaining his PhD in 1959 at Cambridge. After positions in Pakistan and in the US, in 1966 he became founding director of the Institute of Physics at the then new University of Islamabad, which gave Pakistani physics a research base in its own country. The institute is now a department of Quaid-i-Azam University. In 1982 he joined King Fahd University, Dhahran.

DEP and PSL sign distribution agreement

Photodetector supplier Delft Electronic Products (DEP), now in its 30th year of manufacturing for the worldwide image intensifier market, has signed a distributor agreement with Photonic Science Ltd (PSL) for the UK, Eire and France.

PSL, established in the UK in 1985, and with a French office since 1995, specializes in high-technology detector systems, covering imaging applications from X-ray diffraction to night vision. PSL incorporated specially developed DEP intensified tubes into a unique design for what is claimed to be the world’s smallest high resolution intensified camera.

ECFA in Poland

poland1_3-99 — Cracow – Mariacki Church in the market square.

Jagiellonian University’s tradition of natural sciences dates back to the 15th century, when its famous student Nicholas Copernicus revolutionized our view of the universe. Another student, five and a half centuries later, was Karol Wojtyla, Pope John Paul II, who had to receive clandestine education during the Second World War.

The ECFA participants were welcomed by the Dean of the Faculty of Mathematics and Physics of the University, Krzysztof Fialkowski, a theoretical particle physicist. The Jagiellonian University has a strong theoretical physics tradition and has some 40 theorists who carefully follow experimental results.

The University is also well known as the organizer of the Annual Cracow School of Theoretical Physics (Zakopane), that had its 38th session this year. Other schools of theoretical physics in southern Poland are the biennial Katowice School of Theoretical Physics and the annual Cracow Epiphany Conference on Particle Physics. These schools play an essential role in keeping Polish theorists at the forefront of knowledge. The international “Rochester” meeting, held in Warsaw in 1996, also helped put the nation on the world physics map.

Polish theoretical particle physics is very healthy, with about 160 tenured staff, with large concentrations in the Cracow and Warsaw regions, working on many different topics such as electroweak interactions, QCD, neutrino masses and mixing, physics at future accelerators, baryogenesis and cosmology.

In the Cracow region, experimental activities are carried out at the Henryk Niewodniczanski Institute of Nuclear Physics as well as at the Faculty of Physics and Nuclear Techniques of the University of Mining and Metallurgy,
one of the largest academic schools of technology in Poland. These Institutes take part in several high-energy physics experiments at CERN: ATLAS, DELPHI, ALICE, and NA49 as well as EMU13. Moreover, the Cracow groups contribute to both the major experiments at the HERA accelerator at DESY and are in the PHOBOS Collaboration at RHIC, Brookhaven.

Another major centre for experimental research is Warsaw. The researchers from University of Warsaw, Warsaw University of Technology, the Andrzej Soltan Institute for Nuclear Studies, together with colleagues from Bialystok and Kielce, are contributing to several experiments at CERN: DELPHI, NA48, NA49, and WA98 as well as to CMS and ALICE. At DESY, researchers from Warsaw take part in ZEUS and in the TESLA project for the construction of an electronpositron linear collider.

About 190 Polish experimentalists, engineers and technicians are working at CERN and DESY. Around 50 more are involved in a large variety of experiments elsewhere, the biggest groups among them participating in heavy ion experiments to be carried out at RHIC and in the Pierre Auger Observatory air-shower project currently under construction.

A characteristic feature of Polish experimental groups has been their rather large number of highly qualified engineers and technicians. Polish scientists have therefore been able to contribute significantly to detector construction, maintenance and operation. Developing software for event simulation and reconstruction is another speciality. In a number of cases, Poles have made outstanding contributions to physics analysis.

Funding structure and academia

Polish universities are funded by the Ministry of National Education. However, to obtain research grants Polish physicists usually have to apply to the State Committee for Scientific Research (KBN), created in 1991. For institutes outside universities, the KBN may also cover salaries. KBN is independent and objective as it has no institutions of its own to finance. The main disadvantage is, however, that it has too little money for the wide spectrum of activities that fall within its responsibility. Polish scientists are unhappy that the percentage of the GNP allocated to research and development has been steadily decreasing, from 0.76% in 1991 to 0.47% in 1998.

A third major source of funding is the National Atomic Energy Agency (PAA) that supervises a number of Institutes in the atomic, nuclear and plasma physics sectors. It is also responsible for signing agreements with organizations such as CERN and DESY. From 1999 this body will be in charge of paying for the Polish participation in the Joint Institute for Nuclear Research (JINR), Dubna, and CERN. Unfortunately state funding has been insufficient: “We are only getting 40% of what we need.”

Poles working at DESY have also had resources from the PolishGerman Foundation as well as from the German Ministry of Research and Technology, which have made it possible for Polish scientists to work at DESY.

Low salaries

A particularity of the Polish system is that there are practically no fixed-term positions for researchers. A researcher is either a graduate student or is tenured. Low salaries are a major problem. Young people offered a permanent position in the academic sector find it difficult to make ends meet. Graduate students tend to accept hardship for four or five years as an investment in a more profitable future elsewhere. There are also serious difficulties in keeping technical staff. The Warsaw groups, for example, have lost a major proportion of their young and dynamic technical personnel. Another serious problem is that it is expensive to send graduate students to work at CERN.

Some of these points were stressed in a talk by PhD student Anna Stasto. She is a theorist working on QCD, structure functions and neutrino physics. A PhD student earns $200 monthly, about 40% of subsistence level, so many have to find part-time jobs. In spite of this, the number of students has increased. Most of them go on to find jobs at banks, computer and mobile phone companies etc. Only a minority end up as teachers at schools. Some international programmes for student mobility, particularly from Germany and sometimes from national funds, are a boon.

Naturally, the international collaboration in high-energy physics has been very important for raising the level of education of young people, including engineers, and for technology transfer.

Experimental work has led to interesting new partnerships. In Cracow, for example, researchers from the Institute of Nuclear Physics are collaborating with faculty specialists in electronics as well as with specialists in physics and nuclear techniques from the University of Mining and Metallurgy.

High-energy physics has also contributed in some unexpected ways. For example, the former Mayor of Cracow contributed to design work for the HI detector at DESY and the Vice-Mayor was responsible for the mechanical construction of the forward RICH detector in DELPHI.

There seems to be a great public interest in particle physics. A CERN Microcosm exhibition, “From Quarks to Stars”, organized in Cracow and Warsaw three years ago, was a tremendous success. In Cracow, it was visited by more than 25 000 people. Several leading Polish scientists are actively popularizing particle physics, and such efforts are greatly appreciated.

Curie effect

The spirit of Marie Sklodowska Curie (1867-1934) seems to prevail. She was the only person ever to receive Nobel prizes both in physics and in chemistry, in 1903 and 1911 respectively. That was a long time ago, yet Polish women still constitute a large fraction of physicists working in the field of experimental high energy physics – a Curie effect?

Particle and nuclear astrophysics and cosmology committee

A new committee, PaNAGIC (Particle And Nuclear Astrophysics and Gravitational International Committee), was created last October by IUPAP (International Union of Pure and Applied Physics) to support the international exchange of ideas and to nurture the emerging field of particle and nuclear astrophysics and cosmology.

Against the need for larger experiments with increasing costs, the Committee will promote worldwide collaboration and ensure the organization of future experiments.

The Committee will cover the following fields: basic constituents of matter and their interactions by non accelerator means; sources, acceleration mechanisms and the propagation of high-energy particles in the universe; nuclear and particle properties and processes of astrophysical interest in the universe; gravity, including sources of gravitational waves.

The President is Alessandro Bettini, Director of Gran Sasso Laboratories, Underground Physics. Contact “Alessandro.Bettini@lngn.infn.it” or see “http://www.lngs.infn.it“.

Physicists enjoy the CERN School of Computing

The annual CERN School of Computing displays the continual close symbiosis between computing and physics. For the 1998 (21st) CERN School of Computing in Madeira, the programme was organized around four themes: agent and distributed computing technology; intelligent monitoring and control; petabyte storage (databases); and software evolution.

The School was organized by CERN in collaboration with LIP, Lisbon and the University of Madeira. 67 students (from 45 institutes, 22 countries and of 22 nationalities) attended, of which 14 were funded by the European Commission and by UNESCO.

After general lectures in the first week, the second week was oriented towards computing problems for particle physics and the LHC programme.

Practical exercises are an important part of the programme and require a complex computing infrastructure. Computing and peripheral equipment was provided by and via CERN. Equipment lent by various manufacturers was delivered to CERN where it was set up, tested, dismantled and shipped to Funchal, Madeira. Portuguese colleagues ensured the provision of the necessary network connection from Funchal via the University of Madeira, Lisbon and CERN and, together with students from Madeira, helped in the installation. Setting up this complex computing facility, even if only needed for a short time, needed close collaboration and was widely appreciated.

The 22nd CERN School of Computing will take place in Stare Jablonki, Poland, from 12-25 September, organized in collaboration with Warsaw University (IFD) and the Department “Internet For Schools” of the Foundation in Support of Local Democracy (IdS). The themes for 1999 are: advanced topics; LHC experiments data communication and data processing systems; software building; and Internet software technologies.

The School is open to postgraduate students and research workers with a few years’ experience in elementary particle physics, computing or related fields. The number of participants will be about 80, mostly from the CERN Member States or from laboratories closely associated with CERN, but a few may come from elsewhere.

ATLAS of the world

The LHC will collide protons at higher energies (7 TeV per beam) than ever achieved before under laboratory conditions to penetrate still further into the structure of matter and recreate the conditions of the universe just 10¹²seconds after the Big Bang when the temperature was 10¹⁶ degrees. Designing and building a particle physics detector like ATLAS – 7000 tonnes of high technology equipment involves more than just following a sheet of instructions. In a modern-day parallel of a potential Tower of Babel scenario, scientists have to work together as a team while remaining thousands of miles apart.

What is the balance between individual creativity and being part of such a large collaboration?

The successful design and construction of a large and complex state-of-the-art detector requires the creative participation of many people. It is not the collaboration that is creative, but the sum of its individual members. There are many subsystems, so that people mostly work in small groups, contributing creatively. Ensuring that all systems fit and work together, and are affordable, constrains the creative process, but good ideas will make their way!

How are important decisions made? How are individuals heard?

Many important decisions involve just one or two subsystems. They are discussed initially in the subsystem plenary meetings, where everybody can participate and make their voices heard. Recommendations are then discussed in the ATLAS Executive Board, and presented in plenary meetings which play a primary role in forming a consensus when decisions are required. The leadership can only “lead” the collaboration to decisions which are understandable to all, or at least to a large majority. Practical constraints costs, schedule, the availability of manpower etc also come into the equation. There is a clear sequence of steps from subsystem to systems, with the vote by the Collaboration Board being the ultimate step for major decisions.

How is such a large and far-flung collaboration managed?

Each subsystem has its own management team. At the same time, the Executive Board and Spokesperson maintain general oversight.

The Technical Coordination team is responsible for making sure that all subsystems fit together. In parallel, there are national representatives who monitor the use of resources from their respective countries and make sure they are well used.

The Collaboration Board sets out policy issues, and is not involved with execution, which is a management responsibility. However, frequent contacts, between for example the Spokesperson and the Collaboration Board Chair, ensure that policy issues are properly handled, and that fair solutions are found for difficult problems. Finally, direct contacts between individuals and teams with the collaboration management also play an important role.

How do 1800 people communicate among themselves? How do you bridge large distances and overcome time differences?

Electronic communication (e-mail, Web, telephone, video conferencing) is obviously very important. However, regular direct human contacts are crucial. Meetings play a significant role.

How are tasks apportioned?

By trying to match the interests and resources of the participating teams to the tasks. This can succeed only if everyone is also willing to share the less interesting but necessary tasks such as building support structures, contributing to buying cables, writing utility software etc. This works because the physicists are motivated by the prospect of exciting results, which depend on having a complete, working detector system. Of course it is not always easy to arrive at an optimal task-sharing to everyone’s satisfaction, with all tasks assigned.

How are the costs apportioned?

There is no absolute formula. Large teams from wealthy countries are expected to carry a larger share of the costs than small teams from countries with developing economies. Matching the possible contributions of teams and countries to the overall effort is a central part of forming the collaboration.

Where does the money come from?

Mostly from the funding agencies of the various participating countries. There are also significant contributions from CERN, and some resources from individual universities.

How do people join?

Teams interested in ATLAS may contact the Spokesperson, and their interest is then brought to the attention of the Collaboration Board (CB). After examining their resources, their potential share of the work, their relationships with other teams already working on ATLAS etc, the CB votes on their admission.

atlas2_2-99 — Assembling a tile calorimeter for the ATLAS experiment at CERN.

How do you ensure that all the detector pieces fit together?

The Technical Coordinator, supported by the Technical Coordination Team, works with all the subsystem groups to ensure that the separate pieces will fit together without interfering with each other, and that the full detector can be assembled.

How will data analysis be shared among 1800 people?

The data will provide experimental input for many separate research topics. ATLAS scientists will pursue these research areas mostly in small groups working at their home institutions. All collaborators will be invited to analyse the data by being part of analysis teams.

In some respects data analysis by individual ATLAS physicists can be compared to data analysis by astronomers using the Hubble Space Telescope. In both cases, scientists choose the research areas and data that interest them most.

How does a collaborator get credit for his/her contributions?

This is of course a major question. Internal publications within the collaboration, usually with one or a few authors, will document individual contributions. These can be made known to the whole scientific community. Also, leading contributions are often recognized by asking the person to speak at conferences. However, the large collaborations still have to learn how to handle this question. Major results are obtained collectively, because people are willing to share the tasks. It is not only the final analysis which counts, but all the work which makes it possible to collect the data, and calibrate and prepare it for final analysis.

What is the impact of the global spread of the collaboration? How does one contribute from 6000 miles away?

The global spread implies that factors such as transport of components need to be taken into account during the construction, and that communication logistics play a major role. Full information, eventually including data analysis, must be available simultaneously all over the world. Nevertheless, it also implies that scientists from outside Europe have to travel long distances to participate in discussions and meetings, in the detector assembly and testing, and eventually in the operation of the experiment. They may have to spend extended periods away from their homes and home institutions. However, all ATLAS scientists are after the same goal of doing frontline LHC physics, and are therefore willing to endure these inconveniences to achieve that goal. But being away from home is not necessarily always a disadvantage. In particular young people are stimulated by such experience.

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