Since 1993 the Rencontres du Vietnam have fostered exchanges between scientists in the Asia-Pacific region and colleagues from other parts of the world. The 15th edition, which brought together more than 50 physicists in Quy Nhon, Vietnam from 4–10 August, celebrated the 30th anniversary of the start of the Large Electron Positron collider (LEP) in 1989, which within a mere three weeks of running had established that the number of species of light active neutrinos is three (CERN Courier September/October 2019 p32). This was a great opportunity to emphasise the important role that colliders have played and will continue to play in neutrino physics. Before the three-neutrino measurement of LEP, the tau neutrino had been established in the years 1975–1986 by a combination of e+e–-collider observations of tau decays, pp collisions (the W → τντ decay was observed at CERN in 1985) and neutrino-beam experiments, where it was observed that taus are never produced by electron– or muon–neutrino beams (for example Fermilab’s E531 experiment in 1986).
A neutrino-oscillation industry then sprang into being, following the discovery that neutrinos have mass. An abundance of recent results on oscillation parameters were presented from accelerator-neutrino beams, nuclear reactors, and atmospheric and astrophysical neutrinos. Interestingly, the data now seem to indicate at > 3σ that neutrinos follow the natural (rather than inverted) mass ordering, in which the most electron-like neutrino has a mass smaller than that of the muon and tau neutrinos. The next 10 years should see this question resolved, as well as a determination of the CP-violating phase of the neutrino-mixing matrix, with a precision of 5–10 degrees.
The fact that neutrinos have mass requires an addition to the Standard Model (SM), wherein neutrinos are massless by definition. There are several solutions, of which a minimal modification is to introduce right-handed neutrinos in addition to the normal ones, which have left-handed chirality. The properties of these heavy neutral leptons would be very well predicted were it not that their mass can lie anywhere from less than an eV to 1010 GeV or more. Being sterile they only couple to SM particles via mixing with normal neutrinos. Consequently, they should be very rare and have long lifetimes, perhaps allowing a spectacular observation in either fixed-target or high-luminosity colliders at the electroweak scale. One possible low-energy indication could be the existence of neutrinoless double-beta decay. Such decays, currently being searched for directly in dedicated experiments worldwide, violate lepton–number conservation in the case where neutrinos possess a Majorana mass term that transforms neutrinos into antineutrinos.
For a fortunate combination of parameters, this could lead to a spectacular signature
The meeting reviewed the status of all aspects of massive neutrinos, from direct mass measurements of the sort successfully executed shortly after the conference by the KATRIN experiment (see KATRIN sets first limit on neutrino mass) to the search for heavy sterile neutrinos in ATLAS and CMS. A new feature of the field is the abundance of experimental projects searching for very weakly, or, to use the newly coined parlance, “feebly”, interacting particles. These range from CERN’s SHiP experiment to future LHC projects such as FASER and Mathusla (for masses from the pion to the B meson); proposed high-luminosity and high-energy colliders such as the Future Circular Collider would extend the search up to the Z mass for mixings between the heavy and light neutrinos down to 10–11. Until recently classified as exotic, these experiments could yield the long-sought-after explanation for the matter–antimatter asymmetry of the universe by combining CP violation with an interaction that transforms particles into antiparticles. For a fortunate combination of parameters, this could lead to a spectacular signature: the production of a heavy neutrino in a W decay, tagged by an associated charged lepton, and followed by its transformation into its antineutrino, which could then be identified by its decay into a lepton of the same sign as that initially tagged (and possibly of a different flavour).
The meeting was thus concluded in continuity with its initial commemoration: could the physics of neutrinos be one of the highlights of future high-energy colliders?
The 29th International Symposium on Lepton–Photon Interactions at High Energies was held in Canada from 5–10 August at the Westin Harbour Castle hotel, right on the Lake Ontario waterfront in downtown Toronto. Almost 300 delegates provided a snapshot of the entire field of particle physics and, for the first time, parallel sessions were convened from abstracts submitted by collaborations and individuals.
The symposium opened with a welcome from Chief Laforme of the Mississauga First Nation. It was followed by highlights from the LHC experiments and updates on plans for the CERN accelerator complex, the CEPC project in China and the recently inaugurated Belle II programme in Japan. The Belle-II collaboration showed early results from their first 6.5 fb–1 of SuperKEKb data, including measurements of previously studied Standard Model (SM) phenomena and a new limit on dark-photon production near 10 GeV. Further plenary sessions covered dark-matter searches, multi-messenger astronomy, Higgs, electroweak and top-quark physics, heavy-ion physics, QCD, exotic-particle searches, flavour physics and neutrino physics.
Tatsuya Nakada offered his views on flavour factories
The symposium ended with a progress report on the European strategy for particle physics and summaries on advances in particle detection and instrumentation, followed by a presentation on outreach and education initiatives from Kétévi Assamagan (Witwatersrand and BNL), and perspectives on future facilities. In the discussion on future flavour facilities, Tatsuya Nakada (EPFL) offered his views on flavour factories, emphasising their important role in guiding future experiments. He stressed the fact that yesterday’s discoveries (most recently the Higgs boson) become today’s workhorses, providing stringent tests of the SM. In the coming decades we are likely to have W and Higgs factories that will further illuminate the remaining shadows in the SM.
A packed public lecture by 2015 Nobel-Prize winner Art McDonald demonstrated the keen interest of the broader public in the continued developments in particle physics, including those in Canada at the SNOLAB underground laboratory, which now hosts several experiments engaged in neutrino physics and dark-matter searches, following the seminal results from the SNO experiment.
The 16th International Conference on Topics in Astroparticle and Underground Physics (TAUP 2019) was held in Japan from 9–13 September, attracting a record 540 physicists from around 30 countries. The 2019 edition of the series, which covered recent experimental and theoretical developments in astroparticle physics, was hosted by the Institute for Cosmic Ray Research of the University of Tokyo, and held in Toyama – the gateway city to the Kamioka experimental site.
Discussions first focused on gravitational-wave observations. During their first two observing runs, reported Patricia Schmidt from Radboud University, LIGO and Virgo confidently detected gravitational waves from 10 binary black-hole coalescenses and one binary neutron star inspiral, seeing one gravitational-wave event every 15 days of observation. It was also reported that, during the ongoing third observing run, LIGO and Virgo have already observed 26 candidate events. Among them is the first signal from a black hole–neutron star merger.
Guido Drexlin revealed the first measurement results on the upper limit of the neutrino mass
The programme continued with presentations from various research fields, a highlight being a report on the first result of the KATRIN experiment (KATRIN sets first limit on neutrino mass). Co-spokesperson Guido Drexlin revealed the first measurement results on the upper limit of the neutrino mass: < 1.1 eV at 90% confidence. This world-leading direct limit – which measures the neutrino mass by precisely measuring the kinematics of the electrons emitted from tritium beta decays – was obtained based on only four weeks of data. With the continuation of the experiment, it is expected that the limit will be reduced further, or even – if the neutrino mass is sufficiently large – the actual mass will be determined. Due to their oscillatory nature, it has been known since 1998 that neutrinos have tiny, but non-zero, masses. However, their absolute values have not yet been measured.
Diversity is a key feature of the TAUP conference. Topics discussed included cosmology, dark matter, neutrinos, underground laboratories, new technologies, gravitational waves, high-energy astrophysics and cosmic rays. Multi-messenger astronomy – which combines information from gravitational-wave observation, optical astronomy, neutrino detection and other electromagnetic signals – is quickly becoming established and is expected to play an even more important role in the future in gaining a deeper understanding of the universe.
The next TAUP conference will be held in Valencia, Spain, from 30 August to 3 September 2021.
Since joining in 1959, Austria has never stopped contributing to CERN. Associated in bygone days with the UA1 experiment at the SPS, where the W and Z bosons were discovered, and later with LEP’s DELPHI experiment, which helped to put the Standard Model on a solid footing, today hundreds of Austrian scientists contribute to CERN’s experimental programme, and its institutes participate in ALICE, ATLAS, CMS and in experiments at the Antiproton Decelerator. Two of the laboratory’s directors, Willibald Jentschke and Victor Frederick Weisskopf, were born in Austria.
To celebrate the 60th anniversary of Austria’s membership, the public were invited to “Meet the Universe” during a series of exhibitions and public events from 5–12 September, organised by the Institute of High Energy Physics (HEPHY) of the Austrian Academy of Sciences. CERN Director-General Fabiola Gianotti opened proceedings by discussing the role of particle colliders as tools for exploration. The following day, 2017 Nobel Prize winner Barry Barish presented his vision for gravitational-wave detectors and the dawn of multi-messenger astronomy. The programme continued with public lectures by Jon Butterworth of University College London, presenting the various experimental paths that could reveal hints for new physics, and Christoph Schwanda of HEPHY discussing the matter–antimatter asymmetry in the universe.
“We’d like to celebrate this important anniversary and continue to contribute to this long-term endeavour together with the other countries that participate in CERN’s research programme,” said Manfred Krammer, both of HEPHY and head of CERN’s experimental physics department.
The long-standing relationship with CERN has offered broad benefits to the Austrian scientific community, a noticeable example being the Vienna Conference on Instrumentation, and since 1993 the Austrian doctoral programme, which has now trained more than 200 participants, has been fully integrated with CERN’s PhD programme. Today, Austria’s collaboration with CERN extends far beyond particle physics. Business incubation centres were launched in Austria in 2015, and the MedAustron advanced hadron-therapy centre (CERN Courier September/October 2019 p10), which was developed in collaboration with CERN, is among the world’s leading medical research facilities.
“CERN is the place to push the frontiers, and scientists from Austria will contribute to make the next steps towards the unknown,” said HEPHY director Jochen Schieck.
The 2019 edition of New Trends in High Energy Physics took place in Odessa, Ukraine, from 12 to 18 May, with 84 participants attending from 21 countries. Initiated by the Bogolyubov Institute for Theoretical Physics at the National Academy of Sciences in the Ukraine and the Joint Institute for Nuclear Research (JINR) in Dubna, the series focuses on new ideas and hot problems in theory and experiment. The series started in 1992 in Kiev under the name HADRONS, changed its title to “New Trends in High-Energy Physics” at the turn of the millennium, took place for a decade in the Crimea, then moved to Natal (Brazil) and Becici (Montenegro), before coming back to Ukraine this year.
This year’s conference had an emphasis on heavy-ion physics and strong interactions, with aspects of the QCD phase diagram such as signatures of the transition from quark–gluon plasma to hadrons highlighted in several talks. The interpretation of recent experimental results on collectivity (the bulk motion of nuclear matter at high temperatures) in terms of the formation of a “perfect liquid” was also discussed. Future searches for glueballs and other exotic hadronic states will contribute to an improved understanding of non-perturbative aspects of QCD.
Many problems of low and intermediate energy physics are still unresolved
Parallel to the quest for the highest possible energies, many problems of low- and intermediate-energy physics are still unresolved, such as the critical behaviour of excited baryonic matter, the nature of exotic resonances and puzzles relating to spin. The construction of new facilities will help answer these questions, with high-luminosity collisions of particles ranging from polarised protons to gold ions at JINR–Dubna’s NICA facility, complemented by fixed-target antiproton and ion studies with unprecedented collision rates at FAIR, the new international accelerator complex at GSI Darmstadt.
Talks on general relativity and cosmology, dark matter and black holes explored the many facets of modern astrophysical observations. Future multi-messenger observations, combining the measurements of the electromagnetic radiation spectrum and neutrinos with gravitational wave signals, are expected to contribute significantly to an improved understanding of the dynamics of binary black-hole and neutron-star mergers. Such measurements are of great significance for a variety of open issues, for example, nuclear physics at densities far beyond the regime accessible in laboratory experiments.
The next edition of the conference will be held in Kiev from 27 June to 3 July 2021.
A team of researchers from the UK, Germany and the US has used data from the CLAS experiment at Jefferson Laboratory to confirm an anomalous measurement of ⍺– — a key parameter in the theoretical description of the non-leptonic decays of Λ hyperons. ⍺– describes the interference of parity-conserving and parity-violating amplitudes in the matrix element of the decay Λ → pπ–, and its Particle Data Group listing had remained unchanged for over 40 years. The new value will have consequences for heavy-ion physics, measurements of the transverse polarisation of Λ hyperons, the decays of heavier strange baryons, and kaon production.
Prior to this year, the best measurement of ⍺– was derived from π−p→ΛK0 interactions using liquid-hydrogen targets dating from the early 1970s. In May, however, the BESIII collaboration in Beijing published a new measurement ⍺– = 0.750 ± 0.009 (stat) ± 0.004 (syst) based on observations of the decays of ΛΛ pairs from electron-positron collisions at the J/ψ resonance. The collaboration also reported a measurement of the corresponding parameter ⍺+ = −0.758 ± 0.010 (stat) ± 0.007 (syst) for the charge-conjugate decay Λ → p̄π+, consistent with the conservation of CP symmetry — the most sensitive test with Λ baryons so far. The BESIII value is 17% (corresponding to more than five standard deviations) above the previously accepted value, ⍺– = 0.642 ± 0.013. “We suspect previous experiments underestimated some systematic biases in their analyses,” says BESIII spokesperson Yuan Changzheng, of the Institute for High-Energy Physics in Beijing.
David Ireland of the University of Glasgow, and colleagues at George Washington University, the University of Bonn and Forschungszentrum Jülich, have now confirmed the BESIII measurement using kaon photo-production (γp→KΛ) data from the CLAS detector, which operated from 1998 to 2012. Their analysis exploited CLAS measurements of polarisation observables that describe the decay of the recoiling Λ→ pπ– to infer the value of α– using a theoretical tool known as Fierz identities. The value found, α– = 0.721 ± 0.006 (stat) ± 0.005 (syst), is near to, but noticeably below, the BESIII value.
Any experiment that has used this value as part of their analysis should look again
David Ireland
“These data were not measured specifically to evaluate ⍺–,” said Ireland, a former spokesperson of CLAS, “but when the BES result was reported, we realised that they represented a unique opportunity to make an independent estimate of the decay parameter.” Any experiment that has used this value as part of their analysis should look again, he continued. “It would be sensible for the time being to use both the BES and CLAS results to give a range of possible systematic uncertainty.”
The new analysis confirms the BESIII result “very nicely”, concurs Yuan, given that it is based on completely different data and a different technique. “BESIII has now accumulated another 8.7 billion J/ψ events, and the same process will be analysed to
further improve the precision, both statistical and systematic.”
Accelerators of unstable or non-naturally occurring particles, such as the proton–antiproton colliders with which the W, Z and top quark were discovered, famously rely on “beam-cooling” techniques, which reduce the beam’s phase-space volume in order to achieve sufficient interaction rates. Cooling techniques continue to improve, enhancing current and future experiments using low-energy antiprotons, heavy ions and molecular beams, and enabling future muon colliders. The community of scientists and engineers developing and applying beam cooling has been meeting to exchange ideas for more than 20 years at the COOL workshops.
It was gratifying to see the proliferation and progress of beam-cooling technologies at the 12th biennial international workshop on beam cooling and related topics, held from 23–27 September at the Budker Institute of Nuclear Physics (BINP) in Novosibirsk , Russia. Electron-cooling R&D platforms were represented in profusion, including in the US (RHIC at Brookhaven and the planned EIC at Brookhaven and JLab), Germany (COSY at the Forschungszentrum Jülich, the CSR at MPI-K Heidelberg, and R&D at HIM Mainz), China (EICC and HIAF at IMP Lanzhou), CERN (the AD and ELENA), and Russia (NICA at JINR Dubna). Most of these are joint efforts with BINP, which continues to be the primary source for high-voltage, electron-gun and solenoid systems for such coolers. Also represented were stochastic cooling installations, tests of coherent electron cooling, and, at long last, results from the Muon Ionisation Cooling Experiment – notably, the first observation of muon ionisation cooling (first conceived at BINP almost 50 years ago), and a measurement of multiple scattering in a lithium-hydride energy absorber. Results with liquid hydrogen, and a wedge-shaped plastic absorber designed to demonstrate emittance exchange between the transverse and longitudinal planes, are expected soon.
It was unfortunate that no one from a US national laboratory was able to travel to Novosibirsk in person – apparently a casualty of anti-Russia sanctions
Another highlight of the workshop was the report from Brookhaven, “Cooling commissioning results of the first RF-based electron cooler LEReC,” which was delivered remotely by Alexei Fedotov. It was unfortunate that no one from a US national laboratory was able to travel to Novosibirsk in person – apparently a casualty of anti-Russia sanctions. Even at the height of the Cold War, US–USSR scientific contacts in particle and accelerator physics were successfully pursued. The argument that by cutting off such contacts one is shooting oneself in the foot seems quite plausible – after all, we go in order to learn.
Physics-based industries generate over 16% of total turnover and more than 12% of overall employment in Europe, topping contributions from the financial services and retail sectors, according to a report published by the European Physical Society (EPS). The analysis, carried out by UK consultancy firm Cebr (Centre for Economics and Business Research), reveals that physics makes a net contribution to the European economy of at least €1.45 trillion per year, and suggests that physics-based sectors are more resilient than the wider economy.
“To give some context to these numbers, the turnover per person employed in the physics-based sector substantially outperforms the construction and retail sectors, and physics-based labour productivity (expressed as gross value added per employee) was significantly higher than in many other broad industrial and business sectors, including manufacturing,” stated EPS president Petra Rudolf of the University of Groningen. “Our hope is that the message conveyed by the EPS through the study performed by Cebr will be inspiring for the future, both at the European and national levels, making a convincing case for the support for physics in all of its facets, from education to research, to business and industry.”
The Cebr analysis examined public-domain data in 31 European countries for the six-year period 2011-2016. It defined physics-based industries as those where workers with some training in physics would be expected to be employed and where the activities rely heavily on the theories and results of physics to achieve their commercial goals, following the statistical classification of economic activities in the European community (NACE).
Germany showed the highest percentage of turnover from physics-based industries
Based on several different measures of economic growth and prosperity, the analysis found that physics-based goods and services contributed and average of 44% of all exports from the 28 European Union countries during the relevant period. The three major contributions were from manufacturing (42.5%), information & communication (14.1%), followed by professional, scientific & technical activities in physics-based fields such as architecture, engineering and R&D (14.1%). Distributions in employment data were found to be broadly similar, with professional, scientific & technical activities showing the strongest employment growth. Germany showed by far the highest percentage of turnover from physics-based industries (29%), followed by the UK (14.2%), France (12.9%) and Italy 10.4(%).
Taking into account “multiplier impacts” that capture the knock-on effect of goods and services on the wider economy, the analysis found that for every €1 of physics-based output, a total of €2.49 output is generated throughout the EU economy. The employment multiplier is higher still, meaning that for every job in physics-based industries, an average of 3.34 jobs are supported in the economy as a whole by these industries.
The report also found the European physics-based sector to be highly R&D intensive, with expenditure exceeding €22 billion in every year. “However, what seems to be difficult to comprehend for policy makers and for the general public that elects them is that keeping the physics-based sector in the economy strong and addressing global societal challenges is a process of a very long-term nature,” comments Rudolf. “Indeed, it will not suffice to develop technologies on the basis of the current knowledge: new paths and new knowledge will be needed, which can only be generated by open-ended research.”
While the report does not assess the impact of different sub-fields of physics, it is clear that high-energy physics is a major contributor, says former EPS president Rüdiger Voss of CERN. “The sheer scale and technological complexity of big-science projects, and the thousands of highly-skilled people that they produce, makes particle physics, astronomy and other research based on large-scale facilities significant contributors to the European economy – not to mention the fact that these are the subjects that often draw young people into science in the first place.”
The 18th International Conference on Hadron Spectroscopy and Structure, HADRON2019, took place in Guilin, China, from 16 to 21 August, co-hosted by the Guangxi Normal University and the Institute of Theoretical Physics of the Chinese Academy of Sciences. The conference brought together more than 330 experimental and theoretical physicists from more than 20 countries to discuss topics ranging from meson and baryon spectroscopy to nucleon structure and hypernuclei. The central issue was exotic hadrons: the strongly interacting particles that deviate from the textbook definitions of mesons and baryons. Searches for exotic hadrons and studies of their properties have been a focus for many high-energy physics experiments, and many fascinating results have been reported since 2003 when the first particles of this sort were discovered: the hidden-charm X(3872) and the open-charm Ds*0 (2317) observed by Belle and BaBar, respectively. The most cited physics papers of Belle and BESIII and the second most cited of BaBar and LHCb are reports of the discoveries of exotic hadron candidates.
The conference began with a report on LHCb measurements of the doubly charmed Ξ++cc baryon, and the discovery of pentaquark particles called Pc. The higher statistics of the LHC Run-2 data have resolved the Pc(4450) reported by LHCb in 2015 into two narrower structures, Pc(4440) and Pc(4457). In addition, a third hidden-charm pentaquark, Pc(4312), with a smaller mass, was observed for the first time. These Pc structures are very likely exotic baryons consisting of at least five quarks, including a charm quark–antiquark pair. Many theorists believe that these pentaquarks can be described as hadronic molecules of a charmed meson and a charmed baryon, analogous to the deuteron, which is a bound state of a neutron and a proton. A series of parallel talks described theoretical predictions that will be useful in motivating further measurements, such as searches for the decay to a charmed baryon and a charmed meson, and searches for the various new pentaquarks predicted by theoretical models.
The X(3872) discovered by Belle 16 years ago is still the subject of intensive investigations
Illustrating the difficulty of understanding the inner structure of hadrons, the X(3872) discovered by Belle 16 years ago is still the subject of intensive investigations. Its mass is extremely close to the sum of the masses of two charmed mesons, D0 and D*0, and its decay width (< 1.2 MeV) is anomalously small for a hadron of such a mass. New results on its decays into lighter particles were reported by BESIII. Alongside proposals for precise measurements of its mass, width and polarisation at Belle-II, PANDA and the LHC experiments, a deeper understanding of the X(3872) may be just around the corner. A close collaboration between experimentalists and theorists is required, and this conference provided a valuable opportunity to exchange ideas. Interesting discussions will continue at the next HADRON conference, to be held in Mexico in 2021.
Marie Curie once described the laboratory she shared with her husband Pierre as “just a clapboard hut with an asphalt floor and glass roof giving incomplete protection against the rain, without any amenities”. Even her colleagues abroad were shocked by their paltry resources. German chemist Wilhelm Ostwald noted: “The laboratory was a cross between a stable and a potato shed, and if it hadn’t been for the chemical apparatus, I would have thought it a practical joke.” In the 1920s, newspapers showed the desperate situation the French laboratories were in. “There are some in attics, others in cellars, others in the open air…” the Petit Journal newspaper reported in 1921. Increasing research funding to elevate France to the level of countries like Germany became a rallying point for the nation.
In the inter-war years, Jean Perrin, winner of the 1926 Nobel Prize in Physics for his work showing the existence of atoms, championed the development of science and had the support of many other scientists. Thanks to financial support from the Rothschild Foundation, he founded the Institute of Physico-Chemical Biology, the first place to employ researchers full-time. In 1935 he managed to get the National Scientific Research Fund set up to fund academic projects and research fellowships. One of its first fellows was the young Lew Kowarski in 1937, who had joined Frédéric Joliot-Curie’s laboratory at the Collège de France. In May 1939, together with Hans von Halban, they filed patents via the fund that outlined the production of nuclear power and the principle of the atomic bomb.
Around 32,000 people currently work at CNRS in collaboration with universities, private laboratories and other organisations
A new government under Léon Blum took office in 1936, and with it came the appointment of France’s first under-secretary of state for scientific research. Another first was the inclusion of three women in the government at a time when women still did not have the vote in France. Irène Joliot-Curie took up her post for three months in support of women’s rights and scientific research. During this short period, she set out major objectives: an increase in research budgets, salaries and grants for research fellows.
After her resignation, Perrin took over. This sexagenarian with the appearance of a dishevelled scientist “immediately showed the ardour of a young man and the enthusiasm of a beginner, not for the prestige, but for the means of action the post provided”, Jean Zay, the very young minister of national education at the time, noted in his memoirs. Over the next four years, his achievements included the opening of laboratories such as the Paris Institute of Astrophysics and culminated in the decree founding CNRS, published in October 1939. Six weeks after the outbreak of the Second World War, Perrin announced: “Science is not possible without freedom of thought, and freedom of thought cannot exist without freedom of conscience. You cannot require chemistry to be Marxist and expect to produce great chemists; you cannot require physics to be 100% Aryan and expect to keep the greatest physicists in your country… Each of us can die, but we want our ideals to live on.”
The founding principle of the CNRS “to identify and conduct, alone or with its partners, every type of research in the interest of science and the technological, social and cultural advancement of the country” stands strong today. Around 32,000 people, including 11,000 academics and researchers, currently work at CNRS in collaboration with universities, private laboratories and other organisations. Most of the 1100 CNRS laboratories are co-directed with a partner institution and host CNRS personnel and, in the majority of cases, faculties and academics. These “mixed research units”, which were introduced in 1966, form the backbone of French research and allow cutting-edge research to be done whilst being rooted in teaching and contact with students.
Under the auspices of the national ministry of higher education, research and innovation, CNRS is France’s largest research institution. With an annual budget of €3.4 billion, it covers the whole gamut of scientific disciplines, from the humanities to natural and life sciences, the science of matter and the universe, and from fundamental to applied research. The disciplines are organised thematically into 10 institutes, which manage the scientific programmes and a significant share of the investment in research infrastructure. CNRS plays a coordination role, particularly through its three national institutes, the National Institute of Nuclear and Particle Physics (IN2P3), together with the National Institute of Sciences of the Universe and the National Institute for Mathematical Sciences and their Interactions.
When CNRS was founded, French physicists were among the world-leading: Irène and Frédéric Joliot-Curie, Jean Perrin, Louis de Broglie and Pierre Auger are among the names that have entered the history books from this time. Frédéric Joliot-Curie’s laboratory at the Collège de France played a crucial role thanks to its cyclotron, as did Irène Joliot-Curie’s Radium Institute, Louis Leprince-Ringuet’s laboratory at the École polytechnique and Jean Thibaud’s in Lyon. The newly established CNRS put up the funds for facilities, research fellows, technical personnel and chairs of nuclear physics at universities and the elite Grandes Écoles. The war broke out the same year CNRS was founded, bringing everything to a halt: researchers either went into exile or tried to continue running their laboratories in inevitable isolation.
Frédéric Joliot-Curie, buoyed by his involvement in the Resistance, took up the reins of CNRS in August 1944 and strove to help France catch up again after the war, particularly in nuclear physics. After atomic bombs were dropped on Hiroshima and Nagasaki, General de Gaulle asked Frédéric Joliot-Curie and Raoul Dautry, who was minister for reconstruction and urbanism, to set up the Commissariat à l’Energie Atomique (CEA). Frédéric Joliot- Curie saw this organisation as a means of bringing together and coordinating all fundamental research in nuclear physics, including research undertaken in university laboratories. From 1946, all the big names – Auger, Joliot-Curie, Perrin and Kowarski – joined CEA. CNRS was therefore not greatly involved in this area. In 1947 the decision was taken to build a facility in Saclay combining fundamental and applied research. André Berthelot was the director of the nuclear physics division at Saclay and installed several accelerators there.
Founding CERN
In the 1950s French physicists played a key role in the establishment of CERN: Louis de Broglie, the first well-known scientist to call for the creation of a multinational laboratory; Auger, who was director of the department of exact and natural sciences at UNESCO; Dautry, director-general of CEA; Perrin, the high commissioner; and Kowarski, one of CERN’s first staff members who later became director of scientific and technical services. He is credited with the construction of the first bubble chamber at CERN and the introduction of computers. Joliot-Curie, relieved of his duties at CEA owing to his political beliefs, was very upset not to be appointed to the CERN Council – unlike Perrin, who succeeded him at CEA. Alive to CERN’s potential, Louis Leprince-Ringuet shifted the focus of his teams’ research from cosmic rays to accelerators. He became the first French chair of the scientific policy committee (SPC) in 1964 and his laboratory contributed greatly to the involvement of French physicists at CERN.
Another CNRS recruit of the post-war period who also made a name for himself at CERN was Georges Charpak. Securing a research position at CNRS in 1948, he wrote his thesis under the supervision of Frédéric Joliot-Curie, who had wanted to nudge Charpak towards nuclear physics. But he picked his own area: detectors. He was hired at CERN by Leon Lederman in 1963 and went on to develop the multiwire proportional chamber, which replaced bubble chambers and spark chambers by enabling digital processing of the data. The invention won him the 1992 Nobel Prize in Physics.
When he returned to the Collège de France, Frédéric Joliot-Curie joined forces with Irène to create the Orsay campus. Given the prospect of new facilities at CERN, they felt that France needed to develop its own infrastructure to enable French physicists to train and prepare their experiments for CERN. “Helping to create and sustain CERN whilst letting fundamental nuclear-physics research fizzle out in France would be to act against the interests of our country and those of science,” Irène Joliot-Curie wrote in Le Monde. The government under Pierre Mendès France made research a priority and in 1954 granted funds for the construction of two accelerators, a synchrocyclotron at Irène Joliot-Curie’s Radium Institute and a linear accelerator for Yves Rocard’s Physics Laboratory at the École normale supérieure. Irène Joliot-Curie secured the plots required in Orsay for the construction of the Orsay Institute of Nuclear Physics (IPNO) and the Linear Accelerator Laboratory (LAL). Irène Joliot-Curie did not live to see the new laboratory, but Frédéric Joliot-Curie became the IPNO’s first director, while Hans Halban was called back from England to manage LAL. These two emblematic institutes still play a major role in French contributions to CERN.
From strength to strength
During the 1950s and 1960s CNRS went from strength to strength and set up more laboratories for high-energy and nuclear physics. A Cockroft-Walton accelerator, built in Strasbourg by the Germans during the war, was the seed that grew into the Nuclear Research Centre directed by Serge Gorodetsky. Maurice Scherer’s chair in nuclear physics in Caen, created in 1947, evolved into the Corpuscular Physics Laboratory. One of its first doctoral students, Louis Avan, founded the eponymous laboratory in Clermont-Ferrand in 1959. Louis Néel laid the foundations for important physics research in Grenoble, and CEA set up a centre for nuclear studies there in 1956. The Franco-German research reactor was built at the “Institut Laue-Langevin” in Grenoble in 1967. In the same year, the Grenoble Nuclear Science Institute was established, hosting a cyclotron used in particular for the production of radioisotopes for medicine. Its director, Jean Yoccoz, later became a director of IN2P3. The Centre of Nuclear Studies of Bordeaux-Gradignan was established in a disused Bordeaux château in 1969.
The physicists at these laboratories played an active role in CERN experiments, thanks in particular to the flexible secondment policy at CNRS. Among them was Bernard Gregory, who worked at Leprince-Ringuet’s laboratory and focused on the construction of a large, 81 cm liquid-hydrogen bubble chamber in Saclay in preparation for the impending commissioning of the Proton Synchrotron (PS) at CERN. It produced more than 10 million pictures of particle interactions, which were shared all over Europe. In 1965 Gregory became the Director-General of CERN. Five years later, he replaced Louis Leprince-Ringuet as the head of the École polytechnique laboratory, and then became director general of CNRS. He was elected President of the CERN Council in 1977.
Managing expansion
In the 1960s research facilities were becoming so large that the idea came about within CNRS to create national institutes to coordinate the laboratories’ resources and programmes. LAL director André Blanc-Lapierre campaigned for a National Institute of Nuclear and Particle Physics, following the example of the Italian INFN founded in 1951. The aim was to organise the funding allocated to the various laboratories by CNRS, the universities and CEA. Discussions between the partners then began.
In parallel, French physicists were engaged in another debate. After the construction of the 3 GeV proton accelerator SATURNE at CEA in Saclay in 1958 and the 1.3 GeV electron linear accelerator at LAL in Orsay in 1962, as well as the later ACO collider at ALA in Orsay, opinions were divided about building a national machine that would complement CERN’s experimental capabilities and strengthen the French scientific community. Two options were in the running: a proton machine and an electron machine. This decision was especially important since other machines were springing up elsewhere in Europe. In Italy, the electron–positron collider AdA was followed by ADONE in 1969. In Hamburg, Germany, the electron synchrotron DESY was commissioned in 1964.
France’s priority, however, was construction at the European level with CERN, so neither of the two proposed projects ever got off the ground. Jean Teillac, who succeeded Frédéric Joliot-Curie as head of the IPNO, founded IN2P3 in 1971, federating the laboratories and the universities of CNRS. It was only later, in 1975, that CEA and IN2P3 decided to collaborate in building a national machine in Caen, the Large Heavy Ion National Accelerator (“Grand Accélérateur National d’Ions Lourds”, GANIL), which specialised in nuclear physics. Despite the fact that the CEA laboratories involved were not part of IN2P3, the physicists of the two organisations collaborated extensively.
In this context, André Lagarrigue, who had been the director of LAL since 1969, proposed the construction of a new bubble chamber, Gargamelle, on a neutrino beam at CERN. The scientist had previously investigated the feasibility of bubble chambers containing heavy liquids that would favour interactions with neutrinos instead of hydrogen at the École polytechnique. After its construction at Saclay, the chamber filled with liquid freon was installed at CERN and detected neutral currents in 1973. This was a major discovery, which certainly would have won Lagarrigue a Nobel prize had he not died of a heart attack in 1975.
Today, IN2P3 has around 20 laboratories and some 3200 staff, including 1000 academics and researchers in nuclear physics, particle physics, astroparticle physics and cosmology. The institute contributes to the development of accelerators, detectors and observation instruments and their applications to societal needs. Its data centre in Lyon plays an important role in processing and storing large volumes of data, as well as housing the digital infrastructure for other disciplines.
IN2P3 has had strong links with CERN through many projects and experiments. These include: the discovery of the W and Z bosons by UA1 and UA2; contributions to ALEPH, DELPHI and L3 at LEP; the discovery of the Higgs boson by ATLAS and CMS at the LHC; flavour studies at LHCb and heavy-ion physics at ALICE; neutrino physics; CP violation; antimatter experiments, as well as nuclear physics. These joint ventures also involve other CNRS institutes like the INP (Institute of Physics), with its specialists in quantum physics and lasers, as well as in strong magnetic fields.
Future CERN projects are currently being discussed in the update of the European strategy for particle physics. They offer the prospect of new collaborations between CERN and CNRS in high-energy physics, but also in engineering, computing, biomedical applications and even the humanities and social sciences. No doubt the synergy between these two organisations, with their exceptionally rich scientific knowledge, will continue to give birth to exciting new research.
A French version of this article is available here.
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