Praxis Archives – Page 29 of 181

New directions at DESY

**Beate Heinemann** took over as DESY’s director of particle physics in February, and is also professor of experimental particle physics at the Albert Ludwig University of Freiburg. Credit: DESY

What attracted you to the position of DESY director of particle physics?

DESY is one of the largest and most important particle-physics laboratories in the world. I was born and grew up in Hamburg and took my first career steps at DESY during my university studies. I received my PhD there in 1999 and returned as a scientist in 2016, so I know the lab very well. It is a great lab and department, with many opportunities and so many excellent people. I am sure it will be fun to work with all of them and to develop a strategy for the future.

What previous management roles do you think will serve you best at DESY?

Being ATLAS deputy spokesperson from 2013 to 2017 was one of the best roles I’ve had in my career, and I benefitted hugely from the experience. I was fortunate to have an excellent spokesperson in Dave Charlton and I learned a lot from him, as well as from many others I worked with. I try to understand enough details to make educated decisions but not to micromanage. I also think motivating people, listening to them and promoting their talents is key to achieving common goals.

What are the current and upcoming experiments at DESY?

The biggest on-going experimental activities in particle physics are the ATLAS and CMS experiments. We have large groups in both, and for each we are building a tracker end-cap based on silicon-strip detectors at our detector assembly facility, primarily together with German universities. This is a huge undertaking that is currently ongoing for the HL-LHC. Another important activity is to build a vertex detector to be installed in 2023 at the Belle II experiment running at KEK in Japan. We also have a significant programme of local experiments covering axion searches. One of the big projects next summer will be the start of the ALPS II experiment, which will look for axion-like particles by shining an intense laser on a “wall” and seeing if any laser photons appear on the other side, having been transformed into axions by a large magnetic field. We have two other axion experiments planned: BabyIAXO, which looks for axion-like particles coming from the Sun, for which construction is now starting; and MadMax, which looks for axions in the dark-matter halo. Axions were postulated by Peccei and Quinn to solve the strong-CP problem but are also a good candidate for dark matter if they exist. A further experiment, which DESY theorist Andreas Ringwald and I proposed, LUXE, would deliver the European XFEL 16.5 GeV electron beam into a high-intensity laser so that the beam electrons experience a very strong electromagnetic field within their rest frame. LUXE would reach the so-called Schwinger limit, and allow us to see what happens when QED becomes strong and transitions from the perturbative to the non-perturbative regime.

There are many accelerators at DESY, such as PETRA, where the gluon was discovered in the 1970s. Today, PETRA is one of the best synchrotron-radiation facilities in the world and is used for a wide range of science, for example imaging of small structures such as viruses. It is an application of accelerators where the impact on society is more direct and obvious than it is in particle physics.

How can we increase the visibility of particle physics to society?

This is a very important point. The knowledge we get from particle physics today is clear, but it is less clear how we can transfer this knowledge to help solve pressing problems in society, such as climate change or a pandemic. Humankind desires to increase its knowledge, and it is important that we continue with fundamental research purely to increase our knowledge. We have already come so far in the past 5000 years. And, many technical innovations were made for that purpose alone but then resulted in transformative changes. Take the idea of the accelerator. It was developed at Berkeley during the 1930s with no particular application in mind, but today is used routinely around the world to prolong life by irradiating tumours. Or the transistor, without which there would not be any computers, which was developed in the 1920s based on the then-emerging understanding of atoms. It is important to promote both targeted research that directly addresses problems as well as fundamental research, which every now and again will result in groundbreaking changes. When thinking about our projects and experiments we need to keep in mind if and how any of our technical developments can be made in a way that addresses big societal problems.

It is important that we inspire the general public, in particular the young, about science. Educational programmes are key, such as Beamline for Schools, which is one of CERN’s flagship schemes. This was hosted by DESY during Long Shutdown 2 and a team at DESY will continue the collaboration.

CERN recently launched its Quantum Technology Initiative. Does DESY have plans in this area?

DESY received funding from the state of Brandenburg to build a centre for quantum computing, the CTQA, which is located at DESY’s Zeuthen site. Karl Jansen, one of our scientists there, has spent most of his life working on lattice QCD calculations and is leading this effort. I myself am involved in research using quantum computing for particle tracking at the LUXE experiment. The layout of the tracker for this experiment is simpler compared to the LHC experiments, which is why we want to do it here first. We have to understand how to use quantum computers in conjunction with classical computers to solve actual problems efficiently. There is no doubt that quantum computing solves questions that are otherwise not possible, and we also think they will be able to solve problems more efficiently by using less resources compared to classical machines. That could also contribute to reducing the impact of computing on climate change.

What was your participation in the 2020 update of the European strategy for particle physics (ESPPU) and how have things progressed since?

It was exciting to be part of the ESPPU drafting process. I was very impressed by the sincerity and devotion of the people in the hall in Bad Honnef when the process concluded. There was a lot of respect and understanding of the different views on how to balance the scientific ambitions with the realities of funding, R&D needs and other factors.

**Chasing axions** The ALPS II experiment, which will start operating next summer, will search for conversions of photons to axions and back in a strong magnetic field provided by former HERA dipoles. Credit: DESY/Heiner Müller-Elsner

The ESPPU recommended first and foremost to complete the HL-LHC upgrade. This is a big undertaking and demands our focus. For the future, an electron-positron Higgs factory is the highest priority, in addition to ramping up accelerator R&D. Last year an accelerator R&D roadmap was prepared following the ESPPU recommendation. Very different directions are laid out, and now the task is to understand how to prioritise and streamline the different directions, and to ensure the relevant aspects are progressing significantly by the next update (probably in 2026). For instance CERN’s main focus is R&D on the next generation of magnets for a new hadron machine, while DESY has a strong progamme in plasma-wakefield accelerators for electron machines. But both DESY and CERN are also contributing to other aspects and there are other labs and universities in Europe which make important contributions. At DESY we also try to exploit synergies between developing new accelerators for photon science and high-energy physics.

What is the best machine to follow the LHC?

The next machine needs to be a collider that can measure the Higgs properties at the per-cent and even in some cases the per-mille level – a Higgs factory. In addition to the excellent scientific potential, factors to consider are timescale and cost, but also making it a “green” accelerator and considering its innovation potential. Finding a good balance there is not easy, and there are several proposals that were studied as part of the ESPPU.

What are your three most interesting open questions in particle physics?

Mine are related to the Higgs boson. One is the matter–antimatter asymmetry, because the exact form of the electroweak phase transition is closely related to the Higgs field. If it was a smooth transition, it cannot explain the matter–antimatter asymmetry; if it was violent, it could potentially be able to explain it. We should be able to learn something about this with the HL-LHC, but to know for sure we need a future collider. The second question is why is there a muon? Flavour physics fascinates me, and the Higgs-boson is the only particle that distinguishes between the electron, the muon and the tau, which is why I would like to study it extensively. The third question is what is dark matter? One intriguing possibility is that the Higgs boson decays to dark-matter particles, and with a Higgs factory we could measure this, even if it only happens for 0.3% of all Higgs bosons. The Higgs boson is so important for understanding our universe, that’s why we need a Higgs factory, although we will already learn a lot from the LHC and HL-LHC.

Today, women make up more than 30% of the scientists at DESY, whereas in 2005 it was less than 10%

Is the community doing a good job in communicating beyond the field?

It is crucial that scientists communicate scientific facts, especially now when there are “post-truth” tendencies in society. We have a duty as people who are publicly funded to communicate our work to the public. Many people are excited about the origin of the universe and the fundamental laws of physics we are studying. Activities such as the CERN and DESY open days attract many visitors. We also see really good turnouts at public lectures as well as during our “science on tap” activity in Hamburg. I gave a talk about the first minutes of the universe, and the bar was packed and people had many questions during one of these events. We should all spend some of our time communicating science. Of course, we have to mostly do the actual research, otherwise we do not have anything to communicate.

You are the first female director in DESY’s 60-year history. What do you think about the situation for women in physics, for instance the “25 by ‘25” initiative?

The 25 by ‘25 initiative is good. We have been fortunate at DESY that there was a strong drive from the German government. Research funding has increased a lot during the past 10–15 years and there was dedicated funding available to attract women to large research centres. Today, women make up more than 30% of the scientists at DESY, whereas in 2005 it was less than 10%. Having special programmes unfortunately appears to be necessary as change happens too slowly by itself otherwise. Having women in visible roles in science is important. I myself was inspired by several women in particle physics, such as Beate Naroska, the only female professor at the physics department when I was a student, Young-Kee Kim, who was spokesperson of the CDF experiment when I was a postdoc and later deputy-director of Fermilab, and last but not least Fabiola Gianotti, who was spokesperson of ATLAS when I joined and is now the Director-General of CERN.

Standing up for sustainability

Logo of the International Year of Basic Sciences for Sustainable Development 2022. Credit: IYBSSD.

The COVID-19 pandemic has cost more than five million lives and disrupted countless more. Without the results of decades of curiosity-driven research, however, the situation would have been much worse. The pandemic therefore serves as a stark and brutal reminder of the links between basic science and the balanced, sustainable and inclusive development of our planet.

The International Year of Basic Sciences for Sustainable Development (IYBSSD), proclaimed by the United Nations (UN) general assembly on 2 December 2021, is a key moment of mobilisation to convince economic and political leaders, as well as the public, of the critical links between basic research and the 2030 Agenda for Sustainable Development adopted by all UN member states in 2015. Due to their evidence-based nature, universality and openness, basic sciences not only contribute to expanding knowledge and improving societal welfare, but also help to reduce societal inequality, improve inclusion and foster intercultural dialogue and peace. They are thus central in achieving the UN Agenda’s 17 Sustainable Development Goals.

Virtuous circle

Many examples of basic sciences’ transformative contribution to society are so widespread that they are taken for granted. The web was born at CERN from the needs of global particle physics; general relativity underpins the global positioning system; search engines and artificial intelligence rely on brilliant mathematics and statistical methods; mobile phones derive from the discovery of transistors; and Wi-Fi from developments in astronomy. The discovery of DNA, positron emission tomography, magnetic resonance imaging and radiotherapy have transformed medical diagnostics and treatments, while advances in basic physics, chemistry and materials science are reducing pollution and revolutionising the generation and storage of renewable energy.

Basic science, together with applied scientific research and technological applications, is thus one of the key elements of the virtuous circle that allows the sustainable development of society. Yet, basic sciences are often not as prominent as they should be in discussions concerning societal, environmental and economic development. The aims of the IYBSSD are to focus global attention on the enabling role of basic science and to improve the collaboration between basic sciences and policy-making.

Particle physics has a major role to play in making the IYBSSD a success

The IYBSSD, led by the International Union of Pure and Applied Physics – which will celebrate its centenary in 2022 – has received strong support from around 30 international science unions and organisations active in physics, mathematics, chemistry, life science and social science, along with 70 national and international academies of sciences, and 30 Nobel laureates and Fields medallists. A series of specific activities coordinated at local, national and international levels will aim to promote inclusive collaboration (with special attention paid to gender balance), enhance basic-science training and education, and encourage the full implementation of open-access publishing and open data in the basic sciences.

The IYBSSD inauguration ceremony will take place at UNESCO on 8 July, and a closing ceremony is planned to take place at CERN in 2023, hopefully timed with the completion of the Science Gateway building. Events of all sorts proposed by countries, territories, scientific unions, organisations and academies endorsed by the steering committee will occur throughout the year.

The role of particle physics

As one of the most basic sciences of all, particle physics has a major role in making the IYBSSD a success. The high-energy physics community should use all the available opportunities in 2022 and 2023, be it through conferences, workshops, collaboration meetings or other activities, to place our field under the auspices of the IYBSSD. We need to show how this community advances science for the benefit of society, how much it re-enchants our world and therefore makes it worth sustaining, how much it contributes in its practice to openness, equity, diversity and inclusion, and to multicultural dialogue and peace. The CERN model is emblematic of these contributions. Many of the programmes of the CERN & Society foundation also promote these values in line with the IYBSSD objectives.

The need for humanity to maintain and develop high levels of interest and participation in basic sciences makes awareness-raising initiatives such as the IYBSSD critical. Following the recent international years of physics, chemistry, mathematics and astronomy, it is now time for us to get behind this unprecedented, global interdisciplinary initiative

Luciano Girardello 1937–2022

Luciano_Girardello_2022 — Luciano was interested in all aspects of fundamental physics, from quantum field theory to gravity. Credit: Family photograph

Italian theoretical physicist Luciano Girardello passed away in January, aged 84. He made important contributions to quantum field theory, supersymmetry and supergravity, and will always be remembered by friends and colleagues for his irony, vision and great humanity.

Born on 10 September 1937, Luciano graduated at the University of Milano. After a first postdoctoral fellowship at Boulder, Colorado, he worked at many institutions across the world, including Harvard University, the École normale supérieure in Paris and CERN. Upon his return to Italy, he became professor at the University of Milano, where he spent several years, and in 2000 he moved to the new University of Milano-Bicocca, contributing to the creation of its physics department, where he remained for the rest of his career.

Luciano was one of the first to study the mechanisms of supersymmetry breaking, rooting the theory in reality

Luciano was interested in all aspects of fundamental physics, from quantum field theory to gravity, and made seminal contributions to the foundations of supersymmetry and supergravity in their early days. In a fruitful collaboration with other pioneers of the subjects, including Eugène Cremmer, Sergio Ferrara and Antoine Van Proeyen, he investigated the coupling of matter in supergravity, which is fundamental for the experimental search for supersymmetry, the modern theory of gravitation and the effective theories of string compactifications. Luciano was one of the first to study the mechanisms of supersymmetry breaking, rooting the theory in reality. In the final part of his career, he applied the AdS/CFT correspondence, or gauge/gravity duality, to the understanding of fundamental problems in quantum field theory. He was not interested in theoretical speculations or mathematical tricks but rather in understanding the nature of things and in the cross-fertilisation of fields and ideas. Many of his contributions to physics were born in the corridors of the CERN theory division, in long days and endless nights spent with friends and collaborators.

Luciano’s wide and original lectures on different topics at the universities of Milano and Milano-Bicocca inspired students for more than 30 years. His deep thoughts, vision and culture also informed and educated many generations of talented young physicists who are now active in the international arena. Greatly admired as a physicist, he will be remembered by those who had the good fortune to know him well as a great human being, a cultivated and refined person, and an old-time gentleman.

Patricia McBride elected next CMS spokesperson

patty-mcbride-08-0297-11D — Patricia McBride. Credit: Fermilab

Patricia McBride, distinguished scientist at Fermilab, has been elected as the next spokesperson of the CMS collaboration. She will take over from current spokesperson Luca Malgeri in the autumn, becoming the first woman to lead the 3000-strong collaboration.

McBride graduated in physics at Carnegie Mellon University, and completed a PhD at Yale analysing charm decays at Fermilab’s E630 experiment. After a postdoc at Harvard working on the Crystal Ball experiment at DESY and the L3 experiment at CERN, she joined Fermilab in 1994, later becoming head of its scientific computing programmes and head of the Particle Physics Division. Since joining CMS in 2005, she has served as deputy head of CMS Computing, head of the CMS Center at Fermilab and as US CMS Operations programme manager. She was deputy CMS spokesperson from 2018 to 2020.

It will be a challenging, but exciting time for the collaboration
Patricia McBride

Among other appointments, McBride was chair of the American Physical Society (APS) Division of Particles and Fields, the US Liaison Committee of the International Union of Pure and Applied Physics (IUPAP) and the IUPAP Commission for Particles and Fields. In 2009 she was elected as an APS fellow for her original contributions to flavour physics at LEP and the Tevatron, and for the development of major new initiatives in B physics and collider physics.

McBride’s love for particle physics started at the end of middle school when her mother gave her a book about particle accelerators. She will take up the leadership of CMS soon after LHC Run 3 gets under way, and is therefore looking forward to exciting times ahead: “CMS is looking forward to the Run-3 physics programme and at the same time will be pushing to keep the detector upgrades for the HL-LHC on track,” she says. “It will be a challenging, but exciting time for the collaboration.”

David Saxon 1945–2022

Experimental particle physicist David Saxon passed away on 23 January. A native of Stockport, south of Manchester, where his father was a parish minister, he attended the University of Oxford and obtained his doctorate measuring pion–nucleon scattering at the Rutherford Laboratory, followed by a short postdoc there. His doctoral research took him to Paris and Berkeley, where in both cases he reported that his arrival was marked by the onset of student riots.

After a period at Columbia University, he moved to Illinois to work in Leon Ledermann’s group at the newly built Fermilab. Here he helped to develop electron and muon identification techniques, which would prove fruitful in future electroweak experiments. The group did not discover the W and Z, but did find a signal that was later associated with charm mesons. Returning to Rutherford, soon to be Rutherford Appleton Laboratory (RAL), in 1974 David was quickly promoted to senior researcher. Realising that the future lay in “counter” physics, rather than bubble chambers, he worked on hadron–proton scattering in the resonance region. With the PETRA collider at DESY announced soon afterwards, David helped to form the UK contribution to the TASSO experiment, which made important measurements of electron–positron scattering. The PETRA experiments would go on to discover the gluon, enabling the Standard Model to be constructed with confidence.

After PETRA came HERA, which remains the world’s only high-energy electron–proton collider. David first led the RAL team working on the central tracking detector for the ZEUS experiment, but it was not long before he was invited to the newly reinstituted Kelvin professorship at the University of Glasgow, where he arrived in 1990 and spent the remainder of his academic career. He built the group significantly, its present healthy state founded on what he achieved. In addition to taking Glasgow into ZEUS, he nurtured many other activities – in particular involvement in the ALEPH experiment at LEP – and was instrumental in the design of central tracking systems for projects that eventually combined to become ATLAS.

David was instrumental in the design of central tracking systems for projects that eventually combined to become ATLAS

He was hardly installed in Glasgow before being appointed for several years as chair to the UK’s former Particle Physics Committee. There was no more important position to hold at the time, and David’s good sense, insight and intelligence helped to enable the subject to survive and prosper during a time when funding was tight and the UK funding system was being reorganised. Undaunted, he convinced the group in Glasgow that now was an excellent opportunity to host the 1994 edition of ICHEP.

David was one of the most sociable of people, always a good team player and invariably provocative and stimulating in conversation. Inevitably, the call came to move higher up in the university, first as a highly regarded head of department and later as dean of the science faculty – a post he occupied until shortly before his retirement. Meanwhile, he served on numerous local, national and international committees, including the UK CERN delegation and CERN policy committees, where his perceptiveness was always in demand. The UK recognised his distinguished and important contributions to science with the award of an OBE.

It was a sadness that his final years were marked by Parkinson’s disease, but he still participated in CERN Council meetings. He was at all times supported by his wife Margaret, with whom he had a son and a daughter, and found strength and comfort in his church membership. Those who were fortunate enough to know and work with David will never forget his positive and energetic character, always fair-minded, competitive without being aggressive, and caring. He will be much missed, and inspirational memories will remain.

Commemorating Bruno Touschek’s centenary

touschek_featured_img — Bruno Touschek, pictured here in the 1950s, was one of the first physicists in Europe who was
skilled in elementary particle theory and in functioning of accelerators. Credit: F Touschek

Bruno Touschek was born in Vienna on 3 February 1921. His mother came from a well-to-do Jewish family and his father was a major in the Austrian Army. Bruno witnessed the tragic consequences of racial discrimination that prevented him from both completing his high school and university studies in Austria. But he also experienced the hopes of the post-war era and played a role in the post-war reconstruction. With the help of his friends, he continued his studies in Hamburg, where he worked on the 15 MeV German betatron proposed by Rolf Widerøe and learnt about electron accelerators. After the war he obtained his PhD at the University of Glasgow in 1949 , where he was involved in theoretical studies and in the building of a 300 MeV electron synchrotron. Touschek emerged from the early-post war years as one of the first physicists in Europe endowed with a unique expertise in the theory and functioning of accelerators. His genius was nurtured by close exchanges with Arnold Sommerfeld, Werner Heisenberg, Max Born and Wolfgang Pauli, among others, and flourished in Italy, where he arrived in 1953 called by Edoardo Amaldi, his first biographer and first Secretary-General of CERN.

In 1960 he proposed and built the first electron-positron storage ring, Anello di Accumulazione (AdA), which started operating in Frascati in February 1961. The following year, in order to improve the injection efficiency, a Franco-Italian collaboration was born that brought AdA to Orsay. It was here that the “Touschek effect“, describing the loss and scattering of charged particles in storage rings, was discovered and the proof of collisions in an electron-positron ring was obtained.

AdA paved the way to the electron-positron colliders ADONE in Italy, ACO in France, VEPP-2 in the USSR and SPEAR in the US. Bruno spent the last year of his life at CERN, from where – already quite ill – he was brought to Innsbruck, Austria, where he passed away on 25 May 1978 aged just 57.

touschek_sketch — Bruno Touschek’s playful portrayal of T D Lee and parity violation. Credit: F Touschek

Bruno Touschek’s life and scientific contributions were celebrated at a memorial symposium from 2 to 4 December, held in the three institutions where Touschek has left a lasting legacy: Sapienza University of Rome, INFN Frascati National Laboratories and Accademia Nazionale dei Lincei. Contributions also came from the Irène Joliot-Curie Laboratoire, and sponsorship from the Austrian Embassy in Italy.

In addition to Touschek’s impact on the physics of particle colliders, the three-day symposium addressed the present-day landscape. Carlo Rubbia and Ugo Amaldi gave a comprehensive overview of the past and future of particle colliders, followed by talks about physics at ADONE and LEP, and future machines, such as a muon collider, the proposed Future Circular Collider at CERN and the Circular Electron Positron Collider in China, as well as new developments in accelerator techniques. ADONE’s construction challenges were remembered. Developments in particle physics since the 1960s – including the quark model, dual models and string theory, spontaneous symmetry breaking and statistical physics – were described in testimonies from the universities of Rome, Frascati, Nordita and Collège de France.

Touschek’s direct influence was captured in talks by his former students, from Rome and the Frascati theory group, which he founded in the mid 1960s. His famous lectures on statistical mechanics, given from 1959 to 1960, were remembered by many speakers. Giorgio Parisi, who graduated with Nicola Cabibbo, recollected the years in Frascati after the observation of a large hadron multiplicity in e⁺ e^– annihilations made by ADONE, and the ideas leading to QCD.

The final day of the symposium, which took place at the Accademia dei Lincei where Touschek had been a foreign member since 1972, turned to future strategies in high-energy physics, including neutrinos and other messengers from the universe. Also prominent were the many benefits brought to society by particle accelerators, reaffirming the intrinsic broader value of fundamental research.

Touschek’s life and scientific accomplishments have been graphically illustrated in the three locations of the symposium, including displays of his famous drawings on academic life in Roma and Frascati. LNF’s visitor center was dedicated to Touschek, in the presence of his son Francis Touschek.

Costas Kounnas 1952–2022

Renowned Cypriot–French theoretical physicist Costas Kounnas passed away suddenly on 21 January, two days before his 70th birthday. Born in Famagusta, Cyprus, Costas did his undergraduate studies at the National and Kapodistrian University of Athens before moving to Paris for his advanced degree. His studies were interrupted by military service during the events in Cyprus in 1974, after which he completed his PhD at the École polytechnique, carrying out important calculations of QCD effects in deep inelastic scattering and jets. He joined the CNRS in 1980, and later took up a postdoctoral fellowship at CERN, where he made seminal contributions to models of supersymmetry and supergravity. In particular, he helped develop supergravity models in which supersymmetry was broken spontaneously without generating any vacuum energy – a bugbear of globally supersymmetric theories. Working with Costas on these models was one of our most exhilarating collaborations.

Costas then moved to Berkeley where he became a world expert in the construction of string models, showing in particular how they could be formulated directly in four dimensions, without invoking the compactification of extra dimensions. In 1987 he took up a position at the École normale supérieure in Paris, where he remained for the rest of his career, apart from a CERN staff position between 1993 and 1998. Many of his best-known papers during these periods concerned cosmological aspects of string models, loop corrections and the breaking of supersymmetry – topics in which he was a world leader. He was also director of the theoretical physics group at the École normale supérieure between 2009 and 2013.

Costas showed how string models could be formulated directly in four dimensions

Among his accolades, Costas was awarded the Paul Langevin Prize of the French Physical Society in 1995 and the Gay-Lussac Humboldt Prize in 2013 for outstanding scientific contributions, especially to cooperation between Germany and France. In addition, he received a prestigious Research Award from the Adolf von Humboldt Foundation in 2014.

His many friends mourn the passing, not just of a distinguished theoretical physicist, but also of a warm colleague with a great heart that he was not shy of wearing on his sleeve. Costas enjoyed participating exuberantly in scientific discussions, always with the overriding aim of uncovering the truth. We remember a joyful and energetic friend who was passionate about many other aspects of life beyond science, including his many friendships and his home island of Cyprus. He was active in efforts to develop its relations with CERN, where it is now an Associate Member on its way towards full membership.

Ronald Shellard 1948–2021

2021-12-07-1169 Shellard — Ronald Shellard was a long-time proponent of Brazil joining CERN as an Associate Member State. Credit: LIP

Ronald Shellard began his journey in physics in the 1970s at the University of São Paulo, where he took his undergraduate degree, and at the Institute of Theoretical Physics of São Paulo State University, where he completed his master’s in 1973. He received his doctorate, titled “Particle physics field theory, dynamical symmetry breakdown at the two loop and beyond”, from the University of California, Los Angeles in 1978 after also spending time at the University of California, Santa Barbara.

After a period working in theoretical particle physics, Shellard devoted himself to experimental and astroparticle physics. He joined the DELPHI collaboration at the former LEP collider at CERN in 1989, and in 1995 he joined the Pierre Auger Observatory, where he made an outstanding contribution both as a researcher and as an articulator of Brazilian collaboration. Remaining in the astroparticle field, during the past decade he was also involved in the Cherenkov Telescope Array, the Large Array Telescope for Tracking Energetic Sources and the Southern Wide Field Gamma-Ray Observatory.

Shellard played a key role in efforts to make Brazil an official member of CERN

From 2009 to 2013, Shellard was vice president of the Brazilian Physical Society. He participated tirelessly on various initiatives to promote Brazilian physics, such as the establishment of the exchange programme with the American Physical Society, the strengthening of the Brazilian physics Olympiad, the in-depth study of physics and national development, the establishment of the internship programme of high-school teachers at CERN, and the initiative to create a professional master’s degree in physics teaching. He was a member of the Brazilian Academy of Science since 2017, director of the Centro Brasileiro de Pesquisas Físicas since 2015 and president of the Brazilian network of high-energy physics since 2019. He played a key role in efforts to make Brazil an official member of CERN – a process that appears to be reaching a successful conclusion, with the CERN Council voting in September 2021 to grant to Brazil the status of Associate Member State, pending the signature of the corresponding agreement and its ratification by Brazilian authorities. Active until a few days before he passed away on 7 December, Ron was very excited about this news and was making plans for the next steps of the accession procedure.

Ron Shellard had an innovative and sensibly optimistic spirit, with a comprehensive and progressive vision of the crucial role of physics, and science in general, for the progress of Brazilian society. He exerted a great influence on the formation of the research community in high-energy physics. He was the advisor of several graduate students and had a permanent commitment to the training of new scientists and the dissemination and popularisation of science in the country.

Connecting CERN and South Asia

The decision by CERN in 2010 to introduce a policy of geographical enlargement to attract new Member States and Associate Member States, including from outside Europe, marked a prominent step towards the globalisation of high-energy physics. It aimed to strengthen relations with countries that can bring scientific and technological expertise to CERN and, in return, allow countries with developing particle-physics communities to build capacity. From South Asia, researchers have made significant contributions to pioneering activities of CERN over the past decades, including the construction of the LHC.

The first CERN South Asian High Energy Physics Instrumentation (SAHEPI) workshop, held in Kathmandu, Nepal, in 2017, came into place shortly after Pakistan (July 2015) and India (January 2017) became CERN Associate Member States and follows similar regional approaches in Latin America and South-east Asia. Also, within the South Asia region, CERN has signed bilateral international cooperation agreements with Bangladesh (2014), Nepal (2017) and Sri Lanka (2017). The second workshop took place in Colombo, Sri Lanka, in 2019. SAHEPI’s third edition took place virtually on 21 October 2021, hosted by the University of Mauritius in collaboration with CERN. Its aim was to consolidate the dialogue from the first two workshops while strengthening the scientific cooperation between CERN and the South Asia region.

“SAHEPI has been very successful in strengthening the scientific cooperation between CERN and the South Asia region and reinforcing intra-regional links,” said Emmanuel Tsesmelis, head of relations with Associate Members and non-Member States at CERN. “SAHEPI provides the opportunity for countries to enhance their existing contacts and to establish new connections within the region, with the objective of initiating new intra-regional collaborations in particle physics and related technologies, including the promotion of exchange of researchers and students within the region and also with CERN.”

Rising participation

Despite its virtual mode, SAHEPI-3 witnessed the largest participation yet, with 210 registrants. Representatives from Afghanistan, Bangladesh, Bhutan, India, Maldives, Mauritius, Nepal, Pakistan, and Sri Lanka attended, with at least one senior scientist and one student from each country. The workshop brought together physicists and policy makers from the South Asia region and neighbouring countries, together with representatives from CERN. Societal applications of technologies developed for particle physics were key highlights of SAHEPI-3, explained Archana Sharma, senior advisor for relations with international organisations at CERN:

“In this decade, disruptive innovation underpinning the importance of science and technology is making a huge impact towards the United Nations Sustainable Development Goals. CERN plays its role at the forefront, whether it is advances in science and technology or dissemination of that knowledge with an emphasis on inclusive engagement. We see the percolation of this initiative with increasing engagement from the region in CERN programmes.”

Participants reviewed the status and operation of present facilities in particle physics, and the scientific experimental programme, including the LHC and its high-luminosity upgrade at CERN, while John Ellis captivated participants with his talk “Answering the Big Question: From the Higgs boson to the dark side of the Universe”. Sanjaye Ramgoolam topped off the workshop with a public lecture on “the simple and the complex” in elementary particle physics.

SAHEPI has been very successful in strengthening the scientific cooperation between CERN and the South Asia region and reinforcing intra-regional links
Emmanuel Tsesmelis

Country representatives presented several highlights of the ongoing experimental programmes in collaboration with CERN and other international projects. India’s contributions across the ALICE experiment (such as the development of the photon multiplicity detector), its plans to join the IPPOG outreach group, its activities for the Worldwide LHC computing grid, industrial involvement and contributions to CMS – where it is the seventh-largest country in terms of the number of members – were presented. For Afghanistan, representatives described the participation of the country’s first student in the CERN Summer Student School (2019) and the completion of master’s degrees by two faculty members based on measurements at ATLAS. The country hopes to team up with particle physicists outside Afghanistan to teach online courses at the physics faculty at Kabul University, provide postgraduate scholarships to students and involve more female faculty members at ICTP – the International Centre for Theoretical Physics.

Pakistan shared its contributions to the LHC experiments as well as accelerator projects such as CLIC/CTF3 and Linac4 and its role in the tracker alignment of CMS and Resistive Plate Chambers. Nepal representatives described the development of supercomputers at Kathmandu University (KU) and acknowledged the donation agreement between KU and CERN receiving servers and related hardware to set up a high-performance computing facility. In Sri Lanka, delegates highlighted a rising popularity of the CERN Summer Student Programme among university physics students following honours degrees. The country also mentioned its initiative of an island-wide online teacher training programme to promote particle physics. The representative from Bangladesh reported on the country’s long tradition in theoretical particle physics and plans for developing the experimental particle physics community in partnership with CERN. Maldives and Bhutan continue to be growing members from South Asia at CERN, with Bhutan preparing to host the second South Asia science education programme in a hybrid-mode this year.

Strengthening relations
Chief guest Leela Devi Dookun-Luchoomun, the Vice-Prime Minister and Minister of Education, Tertiary Education, Science and Technology of Mauritius, informed the audience about the formation of a research and development unit in her ministry and gave her strong support to a partnership between CERN and Mauritius. The Vice-Chancellor of the University of Mauritius, Dhanjay Jhurry, expressed his deep appreciation of SAHEPI and indicated his support for future initiatives via a partnership between CERN and the University of Mauritius.

The workshop and the initiative to reinforce particle-physics capacity in the region also form part of broader efforts for CERN to emphasise the role of fundamental research in development, notably to advance the United Nations Sustainable Development Goals agenda. In this regard, discussions took place for a follow-up on the first-of-its-kind professional development programme for high-school teachers of STEM subjects from South Asia, held in New Delhi in 2019, with Bhutan volunteering to host the next event in 2023 pandemic permitting. A poster competition engaged students from South Asia, and three prizes were announced to encourage further participation in big-science projects and towards capacity building in the local regions.

The motivation and enthusiasm of SAHEPI-participants was notable, and the efforts in support of research and education across the region were clear. Proceedings of the workshop will be presented to representatives of the governments from the participating countries to raise awareness at the highest political level of the growth of the community in the region and its value for broader societal development.

Discussions will follow in 2023 at SAHEPI-4, helping CERN continue to engage further with particle physics research and education across South Asia for the benefit of the field as a whole.

Roadmaps set a path to post-LHC facilities

The AWAKE plasma-wakefield experiment at CERN is one of a handful of technologies recommended for further study and optimisation. Credit: CERN-PHOTO-201910-349-7

In setting out a vision for the post-LHC era, the 2020 update of the European strategy for particle physics (ESPPU) emphasised the need to ramp up detector and accelerator R&D in the near and long term. To this end, the European Committee for Future Accelerators (ECFA) was asked to develop a global detector R&D roadmap, while the CERN Council invited the European Laboratory Directors Group (LDG) to oversee the development of a complementary accelerator R&D roadmap.

After more than a year of efforts involving hundreds of people, and comprising more than 500 pages between them, both roadmaps were completed in December. In addition to putting flesh on the bones of the ESPPU vision, they provide a rich and detailed snapshot of the global state-of-the-art in detector and accelerator technologies.

Future-proof detectors

Beyond the successful completion of the high-luminosity LHC, the ESPPU identified an e⁺e^– Higgs factory as the highest priority future collider, and tasked CERN to undertake a feasibility study for a hadron collider operating at the highest possible energies with a Higgs factory as a possible first stage. The ESPPU also acknowledged that construction of the next generations of colliders and experiments will be challenging, especially for machines beyond a Higgs factory.

The development of cost-effective detectors that match the precision-physics potential of a Higgs factory is one of four key challenges in implementing the ESPPU vision, states the ECFA roadmap report. The second is to push the limitations in radiation tolerance, rate capabilities and pile-up rejection power to meet the unprecedented requirements of future hadron-collider and fixed-target experiments, while a third is to enhance the sensitivity and affordably expand the scales of both accelerator and non-accelerator experiments searching for rare phenomena. The fourth challenge identified by ECFA is to vigorously expand the technological basis of detectors, maintain a nourishing environment for new ideas and concepts, and attract and train the next generation of instrumentation scientists.

To address these challenges, ECFA set up a roadmap panel, chaired by Phil Allport of the University of Birmingham, and defined six task forces spanning different instrumentation topics (gaseous, liquid, solid state, particle-identification and photon, quantum, calorimetry) and three cross-cutting task forces (electronics, integration, training), with the most crucial R&D themes identified for each. Tasks are mapped to concrete time scales ranging from the present to beyond 2045, driven by the earliest technically achievable experiment or facility start-dates. The resulting picture reveals the potential synergies between concurrent projects pursued by separate communities, as well as between consecutive projects, which was one of the goals of the exercise, explains ECFA chair Karl Jakobs of the University of Freiburg: “It shows the role of earlier projects as a stepping stone for later ones, opening the possibility to evaluate and to organise R&D efforts in a much broader strategic context and on longer timescales, and allowing us to suggest greater coordination,” he says.

Attracting R&D experts and recognising and sustaining their careers is one of 10 general strategic recommendations made by the report. Others include support for infrastructure and facilities, industrial partnerships, software, open science, blue-sky research, and recommendations relating to international coordination and strategic funding programmes. Guided by this roadmap, concludes the report, concerted and “resource-loaded” R&D programmes in innovative instrumentation will transform the ability of present and future generations of researchers to explore and observe nature beyond current limits.

“Ensuring the goals of future collider and non-collider experiments are not compromised by detector readiness calls now for an R&D collaboration programme, similar to that initiated in 1990 to better manage the activities then already underway for the LHC,” adds Allport. “These should be focused on addressing their unmet technology requirements through common research projects, exploiting where appropriate developments in industry and synergies with neighbouring disciplines.”

Accelerating physics

Although accelerator R&D is necessarily a long-term endeavour, the LDG roadmap focuses on the shorter but crucial timescale of the next five-to-ten years. It concentrates on the five key objectives identified in the ESPPU: further development of high-ﬁeld superconducting magnets; advanced technologies for superconducting and normal-conducting radio-frequency (RF) structures; development and exploitation of laser/plasma-acceleration techniques; studies and developments towards future bright muon beams and muon colliders; and the advancement and exploitation of energy-recovery linear accelerator technology. Expert panels were convened to examine each area, which are at different stages of maturity, and to identify the key R&D objectives.

The high-field-magnets panel supports continued and accelerated progress on both niobium-tin and high-temperature superconductor technology, placing strong emphasis on its inclusion into practical accelerator magnets and warning that final designs may have to reﬂect a compromise between performance and practicality. The panel for high-gradient RF structures and systems also identified work needed on basic materials and construction techniques, noting signiﬁcant challenges to improve efﬁciency. Longer term, it flags a need for automated test, tuning and diagnostic techniques, particularly where large-scale series-production is needed.

Energy consumption and sustainability are key considerations in defining R&D priorities and in the design of new machines

In the area of advanced plasma and laser acceleration, the panel focused on rapidly evolving plasma-wakeﬁeld and dielectric acceleration technologies. Further developments require reduced emittance and improved efﬁciency, the ability to accelerate positrons and the combination of accelerating stages in a realistic future collider, the panel concludes, with the goal to produce a statement about the basic feasibility of such a machine by 2026. The panel exploring muon beams and colliders also sets a date of 2026 to demonstrate that further investment is justiﬁed, focusing on a 10 TeV collider with a 3 TeV intermediate-scale facility targeted for the 2040s. Finally, having considered several medium-scale projects under way worldwide, the energy-recovery linacs panel identifies reaching the 10 MW power level as the next practical step, and states that future sustainability rests on developing 4.4 K superconducting RF technology for a next-generation e⁺e^– collider.

In addition to the technical challenges, states the report, new investment will be needed to support R&D and test facilities. Energy consumption and sustainability are explicitly identified as key considerations in defining R&D priorities and in the design of new machines. Having identified objectives, each panel set out a detailed work plan covering the period to the next ESPPU, with options for a number of different levels of investment. The aim is to allow the R&D to be pushed as rapidly as needed, but in balance with other priorities for the field.

Like its detector R&D counterpart, the report concludes with 10 concrete recommendations. These include the attraction, training and career management of researchers, observations on the implementation and governance of the programme, environmental sustainability, cooperation between European and international laboratories, and continuity of funding.

“The accelerator R&D roadmap represents the collective view of the accelerator and particle-physics communities on the route to machines beyond the Higgs factories,” says Dave Newbold, LDG chair and director of particle physics for STFC in the UK. “We now need to move swiftly forwards with an ambitious, cooperative and international R&D programme – the potential for future scientific discoveries depends on it.”

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