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Become a Particle Physicist in Eight Simple Moves

Become a Particle Physicist in Eight Simple Moves

Simone Ragoni is passionate about outreach. His Instagram page, quarktastic, has more than 10 thousand followers, and is one of the very few that successfully makes particle physics and academia relatable. He wrote Become a Particle Physicist in Eight Simple Moves while completing his PhD on the ALICE experiment. The first move is to sip his favourite beverage: coffee.

As a social-media manager and communicator, I’ve been following Ragoni for years. His main tool is humour. And I’m proof it works. I will always remember the basic structure of a proton, because life is indeed full of “ups” and “downs”.

Did I say gentle humour? Nah. Ragoni goes all the way. But he confesses that his humour can only be understood by a handful of people. Particle physics is esoteric – and readers will want to join the club. His book invites you into the world of a young particle physicist. Being a nerd is the new cool.

A highlight is when Ragoni describes how to keep those distributions fit. If you know, you know. There is a pun here and the author explains it very well. He next turns to the tedious work that goes into publishing a paper. “Monte Carlo simulations are our real playground,” he writes, “where we unleash all our fantasy, the perfect world where everything is nice.” But particle physicists are cautious. Five sigma is needed to claim a discovery – a one in 3.5 million chance of being wrong. The author concludes with encouragement to make your own measurements using CERN’s open data.

Ragoni’s book is a delightful gift for anyone whom you want to inspire to become a particle physicist of tomorrow or simply to convey the excitement of what you do, with a quirky bonus of being presented bilingually in English and Italian, should you be keen on improving your physics vocab in one of those languages. It is a gateway to the captivating world of particle physics, skilfully blending humour with profound insights, and inspiring readers to explore further and consider joining the ranks of future particle physicists.

I built a physics museum in my classroom

Teaching modern physics to high-school students presents many challenges: overpacked curricula focusing on classical physics; the depth of knowledge needed by students (and teachers) to understand these topics; and students being over-focused on grades and university admissions. By exposing my students to the work being done at major research laboratories around the world, I have managed to find a way to overcome many of those obstacles.

Some time ago, British Columbia removed provincial examinations, giving teachers a bit more freedom to make additions to their curricula. I chose to insert small one- or two-day units throughout the year, which give my students multiple exposure to modern physics topics. These short introductions over a two-year period mean that physics students don’t need to know all the fine details, which decreases their stress and concerns.

Knowledge sharing

Physics teachers are lucky to have access to high-quality professional development via workshops run by CERN, LIGO, the Perimeter Institute (which produces excellent resources for use in physics classes) and others. These often-week-long events give teachers an overview of how a given research facility works, in the hope that they will bring that knowledge back to their students. Along the way, the teachers attend lectures from leading researchers and see first-hand careers in the field that they can bring back to share with their class.

I have been fortunate enough to attend workshops at these facilities. I have also taken part in a research experience at SNOLAB, brought students on tours of TRIUMF and mentored my students as they conducted research at the Canadian Light Source. All these experiences have given me the knowledge and confidence to introduce the facilities and the work done at them to my students in a way that hopefully piques their curiosity.

The pieces provide a starting point for conversations around what these decommissioned parts were used for and the kind of science they supported

While at CERN for the 2019 international teacher programme, I had the opportunity to visit both the CMS and ALICE detectors and to attend lectures from renowned particle physicists. We spent time in S’Cool LAB and visited many of the behind-the-scenes parts of CERN. While all of these experiences left an imprint on my teaching, it was during quiet visits to what was then called the Microcosm garden – which hosts decommissioned pieces of accelerators and detectors as a form of art – that helped transform the physical space in my classroom.

In 2022 my school in British Columbia renovated a large, old classroom to become our new physics lab. Knowing that I had more space to work with than before, I was inspired to start building my own version of the Microcosm garden on my classroom walls. I soon connected with the outreach team at TRIUMF who were excited to help get my project started with a photomultiplier tube, a control panel from a xenon-gas handling system, a paddle scintillator and a light guide. Since then, I have added a Lucas cell from SNOLAB, a piece of the electron gun from the Canadian Light Source and, most recently, a small-strip half-gap prototype from the New Small Wheel upgrade of the ATLAS detector. The pieces provide a starting point for conversations with students around what these decommissioned parts were used for, and the kind of science they supported.

Equipped with some knowledge of what modern research in the field looks like, I have successfully built a system where I am able to inspire students to want to study physics. Since attending my first major workshop in 2018, I have seen an increase in the number of students entering physics majors. Some of them have already gone on to internships at CERN and TRIUMF, after getting their first exposure to these organisations in my classes. My hope is that by having pieces of the facilities I talk about displayed on my classroom walls, this will further inspire more of my students to want to learn about them, possibly setting them on paths to careers in physics.

A new generation, a new vision

The 2024 Aspen Winter Conference, The Future of High Energy Physics: A New Generation, A New Vision, attracted 50 early-career researchers (ECRs) from across the world to the Aspen Center for Physics, 8000 feet above sea level in the Colorado Rockies, from 24 to 29 March. The conference built on the many new ideas that arose from the recent Snowmass process of the US particle physics community (CERN Courier January/February 2024 p7). The conference sought to highlight the role of ECRs in realising bold long-term visions for the field, covering theoretical questions, the experimental vision for the next 50 years and the technologies required to make it a reality. Students, postdocs and junior faculty are often the drivers of new ideas in science. Helping them transition new ideas to the mainstream requires enthusiasm, community support and time.

Crossing frontiers

85% of the matter in the universe at most minimally interacts with the electromagnetic force but provided the gravitational seed for large-scale structure formation in the early universe. Hugh Lippincott (University of California, Santa Barbara) summarised cross-frontier searches. Pursuing all possible scenarios via direct detection will require scaling up existing technology and developing new technologies such as quantum sensors to probe lighter dark-matter candidates. On the one hand, the 60 to 80 tonne “XLZD” liquid xenon detector will merge the expertise of the XENONnT, LUX-ZEPLIN and DARWIN collaborations; on the low-mass side, Reina Maruyama (Yale) discussed the ALPHA and HAYSTAC haloscopes, which seek to convert axions into photons in highly tuned resonant cavities. Indirect detection and collider experiments will also play an important role in closing in on minimal dark-matter models.

Delegates expressed a sense of urgency to probe higher energies. Cari Cesarotti (MIT) advocated R&D towards a future muon collider, arguing that muons offer a clean and power-efficient route to the 10 TeV scale and above. Recently, experts have estimated that challenges due to the finite muon lifetime could be overcome on a 20-year technically limited timeline. Both CERN and China have proposed building 100 km-circumference tunnels, initially hosting an electron–positron collider followed by a 100 TeV hadron machine, however, the timeline suggests that almost all of the conference attendees would be retired before hadron collisions come online. Elliot Lipeles (Pennsylvania) proposed skipping the electron-positron stage and immediately pursuing an intermediate-energy hadron collider: existing magnets in a 100 km tunnel could produce 37 TeV collisions, advancing measurements of the Higgs self-coupling and electroweak phase transition, dark matter and its mediators, and naturalness.

The energy, intensity and cosmic frontiers of particle physics target deeply connected questions

Neutrinos were discussed at length. Georgia Karagiorgi (Columbia University) argued that three short-baseline anomalies remain, potentially hinting at additional sterile neutrinos or dark-sector portals. Julieta Gruszko (North Carolina at Chapel Hill) presented an exciting future for experiments that seek to discern the fundamental nature of neutrinos. A new tonne-scale generation of detectors comprising LEGEND1000, nEXO and CUPID may succeed in confirming the Majorana nature of the neutrino if they observe neutrinoless double beta decay.

Talks on the importance of science communication and education provoked a great deal of discussion. Ethan Siegal, host of popular podcast “Starts with a Bang” spoke on public outreach, Kevin Pedro (Fermilab) on advocacy with policy­makers in Washington, DC, and Roger Freedman (University of California Santa Barbara) on educating the next generation of physicists. In public programming, Nausheen Shah (Wayne State) was the guest speaker at a screening of Hidden Figures, the inspiring true story of the black women who helped the US win the space race, and Philip Chang (University of California San Diego) lectured on “An Invitation to Imagine Something from Nothing”.

The energy, intensity and cosmic frontiers of particle physics target deeply connected questions. Dark matter, dark energy, cosmic inflation and baryogenesis have remained unexplained for decades, and the structure of the Standard Model itself provokes questions, not least in relation to the Higgs boson and neutrinos. Innovative and complementary experiments are needed across all areas of particle physics. Judging from the 2024 Aspen Winter Conference, the future of the field is in good hands.

Threshold moment for medical photon counting

7th Workshop on Medical Applications of Spectroscopic X-ray Detectors participants

The seventh workshop on Medical Applications of Spectroscopic X-ray Detectors was held at CERN from 15 to 18 April. This year’s workshop brought together more than 100 experts in medical imaging, radiology, physics and engineering. The workshop focused on the latest advancements in spectroscopic X-ray detectors and their applications in medical diagnostics and treatment. Such detectors, whose origins are found in detector R&D for high-energy physics, are now experiencing a breakthrough moment in medical practice.

Spectroscopic X-ray detectors represent a significant advancement in medical imaging. Unlike traditional X-ray detectors that measure only the intensity of X-rays, these advanced detectors can differentiate the energies of X-ray photons. This enables enhanced tissue differentiation, improved tumour detection and advanced material characterisation, which may lead in certain cases to functional imaging without the need for radioactive tracers.

The technology has its roots in the 1980s and 1990s when the high-energy-physics community centred around CERN developed a combination of segmented silicon sensors and very large-scale integration (VLSI) readout circuits to enable precision measurements at unprecedented event rates, leading to the development of hybrid pixel detectors (see p37). In the context of the Medipix Collaborations, CERN has coordinated research on spectroscopic X-ray detectors including the development of photon-counting detectors and new semiconductor materials that offer higher sensitivity and energy resolution. By the late 1990s, several groups had proofs of concept, and by 2008, pre-clinical spectral photon-counting computed-tomography (CT) systems were under investigation.

Spectroscopic X-ray detectors offer unparalleled diagnostic capabilities, enabling more detailed imaging and earlier and precise disease detection

In 2011, leading researchers in the field decided to bring together engineers, physicists and clinicians to help address the scientific, medical and engineering challenges associated with guiding the technology toward clinical adoption. In 2021, the FDA approval of Siemens Healthineers’ photon-counting CT scanner marked a significant milestone in the field of medical imaging, validating the clinical benefits of spectroscopic X-ray detectors. The mobile CT scanner, OmniTom Elite from NeuroLogica, approved in March 2022, also integrates photon counting detector (PCD) technology. The 3D colour X-ray scanner developed by MARS Bioimaging, in collaboration with CERN based on Medipix3 technology, has already shown significant promise in pre-clinical and clinical trials. Clinical trials of MARS scanners demonstrated its applications for detecting acute fractures, evaluation of fracture healing and assessment of osseous integration at the bone–metal interface for fracture fixations and joint replacements. With more than 300 million CT scans being performed annually around the world, the potential impact for spectroscopic X-ray imaging is enormous, but technical and medical challenges remain, and the need for this highly specialised workshop continues.

The scientific presentations in the 2024 workshop covered the integration of spectroscopic CT in clinical workflows, addressed technical challenges in photon counting detector technology and explored new semiconductor materials for X-ray detectors. The technical sessions on detector physics and technology discussed new methodologies for manufacturing high-purity cadmium–zinc–tellurium semiconductor crystals and techniques to enhance the quantum efficiency of current detectors. Sessions on clinical applications and imaging techniques included case studies demonstrating the benefits of multi-energy CT in cardiology and neurology, and advances in using spectroscopic detectors for enhanced contrast agent differentiation. The sessions on computational methods and data processing covered the implementation of AI algorithms to improve image reconstruction and analysis, and efficient storage and retrieval systems for large-scale spectral imaging datasets. The sessions on regulatory and safety aspects focused on the regulatory pathway for new spectroscopic X-ray detectors, ensuring patient and operator safety with high-energy X-ray systems.

Enhancing patient outcomes

The field of spectroscopic X-ray detectors is rapidly evolving. Continued research, collaboration and innovation to enhance medical diagnostics and treatment outcomes will be essential. Spectroscopic X-ray detectors offer unparalleled diagnostic capabilities, enabling more detailed imaging and earlier and precise disease detection, which improves patient outcomes. To stay competitive and meet the demand for precision medicine, medical institutions are increasingly adopting advanced imaging technologies. Continued collaboration among researchers, physicists and industry leaders will drive innovation, benefiting patients, healthcare providers and research institutions.

Wonderstruck wanderings

An illustration of a flea from Robert Hooke’s Micrographia

The wonder and awe that we sense when we look at the starry skies is a major motivation to do science. Both Plato (Theaetetus 155d) and Aristotle (Metaphysics 982b12) wrote that philosophy starts in wonder. Plato went even further to declare that the eye’s primary purpose is none other than to see and study the stars (Timaeus 47c). But wonder and awe also play a wider role beyond science, and are fundamental to other endeavours of human civilisation, such as religion. In Wonderstruck: How Wonder and Awe Shape the Way We Think, Helen De Cruz (Saint Louis University) traces the relationship between wonder and awe and philosophy, religion, magic and science, and the development of these concepts throughout history.

Essential emotion

De Cruz’s book is rich in content, drawing from psychology, anthropology and literature. Aptly for particle physicists, she points out that it is not only the very largest scales that fill us with awe, but also the very smallest, as for example in Robert Hooke’s Micrographia, the first book to include illustrations of insects and plants as seen through a microscope. Everyday things may be sources of wonder, according to philosopher and rabbi Abraham J Heschel, who has written on religion as a response to the awe that we feel when we look at the cosmos. Even hard-nosed economists recognise the fundamental role of wonder, she observes: Adam Smith, the famous economist who wrote The Wealth of Nations, believed that wonder is an essential emotion that underlies the pursuit of science, as it prompts people to explore the unknown and seek knowledge about the world. Although particle physics is not mentioned explicitly in the book – the closest instance is a quote from Feynman’s Lectures on Physics – the implications are clear. And while the sources quoted are mostly Western, other traditions are not ignored, with references to Chinese and Japanese culture present, among others.

Wonderstruck

The book also motivates questions that it does not address, some of which are especially interesting for funda­mental physics. For example, modern human beings who live and work in cities spend most of their lives in an environment that alienates them from nature, and nature-induced awe must compete with technology-driven amazement. One can maybe glimpse that in outreach, where curiosity about technology sometimes, though not always, eclipses interest about the fundamental questions of science. While the book discusses this topic in the context of climate change – a reality that reminds us that we cannot ignore nature – there is more one can do with respect to the effects of such an attitude in motivating fundamental science.

At a time when large scientific projects, such as CERN’s proposed Future Circular Collider, are being considered, generating a lot of discussions about cost and benefit, this book reminds us that the major motivation of a new telescope or collider is to push into the frontiers of the unknown – a process that starts and finishes with wonder and awe. As such, the book is very useful reading for scientists doing fundamental research, especially those who engage with the public.

Near-detector upgrade in place at T2K

Neutrino physics requires baselines both big and small, and neutrinos both artificial and astrophysical. One of the most prominent experiments of the past two decades is Tokai-to-Kamioka (T2K), which observes electron–neutrino appearance in an accelerator-produced muon–neutrino “superbeam” travelling coast to coast across Japan. To squeeze systematics in their hunt for leptonic CP violation, the collaboration recently brought online an upgraded near detector.

“The upgraded detectors are precision detectors for a precision-physics era,” says international co-spokesperson Kendall Mahn (Michigan State). “Our current systematic constraint is at the level of a few percent. To make progress we need to be able to probe regions we’ve not probed before.”

T2K studies the oscillations of 600 MeV neutrinos that have travelled 295 km from the J-PARC accelerator complex in Tokai to Super-Kamiokande – a 50 kton gadolinium-doped water-Cherenkov detector in Kamioka that has also been used to perform seminal measurements of atmospheric neutrino oscillations and constrain proton decay. Since the start of data taking in 2010, the collaboration made the first observation of the appearance of a neutrino flavour due to quantum-mechanical oscillations and the most precise measurement of the θ23 parameter in the neutrino mixing matrix. As well as placing limits on sterile-neutrino oscillation parameters, the collaboration has constrained a wide range of the parameters that describe neutrino interactions with matter. The uncertainties of such measurements typically limit the precision of fits to the fundamental parameters of the three-neutrino paradigm, and constraining neutrino-interaction systematics is the main purpose of near detectors in superbeam experiments such as T2K and NOvA, and the future ones Hyper-Kamiokande and DUNE.

T2K’s near-detector upgrade improves the acceptance and precision of particle reconstruction for neutrino interactions. A new fine-grained “SuperFGD” detector (see pink rectangle, left, on “New and improved” image) serves as the target for neutrino interactions in the new experimental phase. Comprised of two million 1 cm3 cubes of scintillator strung with optical fibres, SuperFGD lowers the detection threshold for protons ejected from nuclei to 300 MeV/c, improving the reconstruction of neutrino energy. Two new time-projection chambers flank it above and below to more closely mimic the isotropic reconstruction of Super-Kamiokande. Finally, six new scintillator planes suppress particle backgrounds from outside the detector by measuring time of flight.

Following construction and testing at CERN’s neutrino platform, the new detectors were successfully integrated in the experiment’s global DAQ and slow-control system. The first neutrino-beam data with the fully upgraded detector was collected in June, with the collaboration also benefitting from an upgraded neutrino beam with 50% greater intensity. Beam intensity is set to increase further in the coming years, in preparation for commissioning the new 260 kton Hyper-Kamiokande water Cherenkov detector. Cavern excavation is underway in Kamioka, with first data-taking planned for 2027.

But much can already be accomplished in the new phase of the T2K experiment, says the team. As well as improving precision on θ23 and another key mixing parameter Δm223, and refining the theoretical models used in neutrino generators, T2K will improve its fit to δCP, the fundamental parameter describing CP violation in the leptonic sector. Measuring its value could shed light on the question of why the  universe is dominated by matter.

“T2K’s current best fit to δCP is –1.97,” says Mahn. “We expect to be able to observe leptonic CP violation at 3σ significance if the true value of δCP is –π/2.”

The full spectra of particle physics

All aspects of particle physics

This textbook for advanced undergraduate and graduate students, written by experimental particle-physicist Pascal Paganini of Ecole Polytechnique, aims to teach Standard Model calculations of quantities that are relevant for modern experimental research. Each chapter ends with a collection of unsolved problems to help the student practice the discussed calculations. The level is similar to the well-known textbook Quarks and Leptons by F Halzen and A D Martin (Wiley, 1984), but with a broader introduction and including more up-to-date material. The notation is also similar, and shared with several other popular textbooks at the same level, making it easy for students to use it along with other resources.

Comprehensive

Fundamentals of Particle Physics starts with a general introduction that is around 50 pages long and includes information on detectors and statistics. It continues with a recap of relativistic kinematics, quantum mechanics of angular momentum and spin, phase–space calculations for cross sections and decays as well as symmetries. The main part of the book begins with a discussion of relativistic quantum mechanics, covering the equations of motion of spin 0, 1 and ½ particles along with a detailed description of Dirac spinors and their properties. Then, it addresses quantum electrodynamics (QED), including the QED Lagrangian, standard QED cross-section calculations and a section dedicated to magnetic moments (g-2). About 100 pages are devoted to hadronic physics: deep inelastic scattering, parton model, parton-distribution functions and quantum chromodynamics (QCD). Calculations in perturbative QCD are discussed in some detail and there is also an accessible section in non-perturbative QCD that can serve as a very nice introduction to beginner graduate students.

Fundamentals of Particle Physics

The book continues with weak interactions, covering the Fermi theory, W-boson exchange, CKM matrix, neutrinos, neutrino mixing and CP-violation. The following chapter presents the electroweak theory and introduces gauge-boson interactions. A dedicated chapter is reserved for the Higgs boson. This includes a nice section about the discovery of the particle and the measurements that are performed at the LHC, as well as some comments about the pre-history (LEP and Tevatron) and the future (HL-LHC and FCC). A clear discussion about naturalness and several other conceptual issues offers a light and useful read for students of any level. The final chapter goes through the Standard Model as a whole, including a very useful evaluation of its successes and weaknesses. In terms of beyond-Standard Model physics, only dark matter and neutrino masses are covered.

Although this is not a quantum field-theory textbook, some of its elements are introduced; in particular second quantisation, S-matrix, Dyson’s expansion and a few words about renormalisation are included. These are very useful in bridging the gap between practical calculations and their theoretical background, also serving as a quick reference.

There are several useful appendices, most notably a 30-page introduction to group theory that can serve as a guide for a short standalone course in the subject or as a quick reference. The book also includes elements of the Lagrangian formalism, which could have been a bit more expanded to include a more detailed presentation of Noether’s theorem, probably in an additional appendix.

Overall the book achieves a good balance between calculations and more conceptual discussions. All students in the field can benefit from the sections on the Higgs-boson discovery and the Standard Model. Being concise and not too long, Fundamentals of Particle Physics can easily be used as a primary or secondary textbook for a particle-physics course that introduces calculations using Feynman diagrams in the Standard Model to students.

Ilario Boscolo 1940–2024

Ilario Boscolo

Ilario Boscolo, who was one of the proponents of the AEgIS experiment at CERN, passed away on 16 April 2024 at the age of 84.

Ilario Boscolo was born in Codevigo, Italy in 1940 and graduated from the nearby University of Padua. In 1968 he joined the University of Lecce, where he initiated research in accelerator physics, high-intensity electron beams and free electron lasers (FELs), and far-infrared and CO2 lasers. Among his important scientific contributions at that time were the development of a prototype electrostatic accelerator, investigations on far-infrared lasers optically pumped in a cavity, and a much-cited theoretical proposal for a two-stage FEL for coherent harmonic amplification (an optical klystron). Ilario spent long periods of study in international research institutes, including the ENEA fusion energy centre in Frascati and the University of California Santa Barbara, where he collaborated with world-leading FEL researchers Luis Elias and William Colson.

In 1987 Ilario was called to the University of Milan, where he became full professor, to participate in the INFN project ELFA (electron laser facility for acceleration) and was responsible for the photocathode emission. His interest then turned to other topics, including efficient electron sources based on field emission from carbon nanotubes or ferroelectric ceramics and, within CERN, pulsed laser phase coding systems for new acceleration facilities. Within the INFN SPARC–SPARX initiative, started in 2003 and based in Frascati, he focused on laser applications for the development of pulsed, high-brightness UV and X-ray FEL sources. In particular, he showed that the high beam quality of the electron sources depends on suitable shaping of comb laser pulses, the study of which was realised in a dedicated laser laboratory at Milan founded by Ilario.

In 2007 Ilario was one of the proponents of the AEgIS experiment at the CERN Anti­proton Decelerator, which aimed to investigate the properties of antimatter, in particular its gravitational interactions. This required the production of a low-energy beam of antihydrogen atoms, obtained by a charge-exchange process with positronium atoms laser-excited at Rydberg levels. Led by Ilario, the Milan laser laboratory was responsible for the laser system that was required to make this pairing possible. AEgIS demonstrated the first pulsed-production of antihydrogen atoms in 2018, enabling a series of antimatter studies that are ongoing.

In all his activities, Ilario showed great passion and enthusiasm for both science and its applications. This positive attitude was also widely displayed through his didactical activity in various courses at the University of Milan. He was responsible for a new physics laboratory for the biology programme and for the laser laboratory for the physics programme. In addition, his greatest success was the complete reconstruction of the general physics laboratory for first-year students. By encouraging students to practice and elaborate on their own, with only little guidance from the teacher, this laboratory left an indelible mark on their training as physicists.

Another strong passion of Ilario was civil commitment, reflected in his constant engagement with university governance and studies of politics and economics, to which he dedicated himself with his usual inexhaustible enthusiasm, particularly after his retirement.

Ilario is remembered by his collaborators and students as a person of great culture, of brilliant insights, of a willingness to discuss physics and politics with anyone, and as an exquisite friend. He was a true scientist, leaving a deep mark on physics and a bright memory for everyone who had the honour of knowing him.

Alec Geoffrey Hester 1928–2024

Alec Hester, a former editor of CERN Courier and later physics subject specialist at the CERN library for nearly 30 years, passed away in Geneva on 9 March at the age of 96.

Born in Hatfield, to the north of London, in 1928, Alec graduated in physics from Imperial College London in 1949. He continued there for his PhD, building a Van de Graaff accelerator to study (p, alpha) reactions in light nuclei. Yes, in those days postgraduate students built their own accelerators! One of his older fellow students was Don Perkins, who passed away in 2022.

In 1952 Alec interrupted his studies to take a job in the publicity department of General Electric at its site in Kent, England. Nine years later he came to CERN to take over the editorship of CERN Courier from Roger Anthoine. The Courier was then just two years old, and it was during Alec’s period as editor that it began to move beyond its initial role as the house journal for CERN staff to one that communicated the work of CERN and other laboratories to a wider scientific and technical readership. Marking the end of Alec’s editorship in the December 1965 issue, Anthoine wrote: “The editing and production of our periodical, with limited means, requires not only very definite intellectual qualities, for collecting and processing information from all over the Laboratory, but also considerable physical and moral toughness to cope with the many dictates of production, which are the lot of every editor… It is mainly thanks to [Alec’s] drive that CERN Courier, which now has a circulation of 6000 copies (French and English versions combined), has risen from the rank of ‘internal information journal’ to that of ‘world spokesman for European sub-nuclear physics’.”

In 1966 Alec moved to the CERN scientific information service as the physics subject specialist, remaining there until his retirement in February 1993. His accurate and painstaking work developing the library’s bibliographic databases provided the nucleus for those searchable on the CERN Document Server today.

Alec leaves behind Annemarie, his wife for over 70 years, his daughters Barbara and Dagmar, and his four grandchildren.

Rudolf Bock 1927–2024

Rudolf Bock

Renowned experimental physicist and co-initiator of relativistic heavy-ion physics, Rudolf Bock, passed away on 9 April 2024 aged 96.

Rudolf Bock was born in Mannheim, Germany in May 1927 and obtained his diploma in physics from the University of Heidelberg in 1954. He conducted his doctoral thesis on deuteron-induced nuclear reactions at the cyclotron of the Max Planck Institute for Medical Research in Heidelberg and received his doctorate from Heidelberg University in 1958. He then investigated nuclear reactions at the newly founded MPI for Nuclear Physics (MPIK) at the tandem accelerators there, initially with light ions and from 1963 with heavier ions.

In 1967 he was appointed full professor at the University of Marburg and was involved in the development of a joint accelerator project for heavy-ion research, ultimately leading to the UNILAC accelerator project. On 17 December 1969, the research centre GSI (Gesellschaft für Schwerionenforschung) was founded in Darmstadt–Wixhausen. As one of its founding fathers and subsequently as a long-standing member of the GSI board of directors, Rudolf Bock played a decisive role in the development of nuclear physics with heavy ions. At the same time, he maintained his contacts with Heidelberg as an honorary professor and as an external scientific member of the MPIK. In 2000 he was awarded an honorary doctorate from Goethe University Frankfurt.

Research with relativistic heavy-ion beams soon led to great successes. From 1974 Rudolf Bock established a working group at GSI under the leadership of Hans Gutbrod and Reinhard Stock, who set up and successfully carried out two major experiments at the Berkeley Bevalac accelerator. These resulted in the discovery of compressed, hot nuclear matter with hydrodynamic flow behaviour and thus formed the basis for his later experiments on quark–gluon plasma at CERN.

From the mid-1980s, the heavy-ion synchrotron SIS18 was set up at GSI under the leadership of director Paul Kienle. Thanks to Rudolf Bock’s guidance and in cooperation with surrounding universities, three new experiments (FOPI, KAOS and TAPS) were created, which focused on the formation of compressed nuclear matter as well as on hadron production and in particular the formation of light atomic nuclei. Around the same time, he was working on plans for experiments at much higher energies, which could ultimately only be realised at the CERN
SPS accelerator, with decisive contributions from GSI and LBL Berkeley. This led to the development of today’s global programme in ultra-relativistic nuclear–nuclear collisions, which has been pursued since the 1990s at the AGS and SPS, from 2000 with four experiments at RHIC and, since 2010, has been led by ALICE at the LHC at the highest energies.

The cooperation between GSI and LBL Berkeley was not only the beginning of relativistic heavy-ion physics. Supported by Hermann Grunder, then head of the LBL accelerator department, Rudolf Bock started the inertial confinement fusion programme in Germany. He also laid an important foundation for ion-beam therapy by supporting the secondment of Gerhard Kraft from GSI to the cancer-therapy programme at LBL. After his retirement in December 1995, Rudolf Bock maintained his scientific activities at GSI, his primary interest being the development of experiments on plasma physics and inertial-confinement fusion with high-intensity ion and laser beams.

Throughout the course of his scientific career, Rudolf Bock established numerous new research collaborations with institutes in Germany and abroad. As he himself had taken part in the Second World War and had spent several years as a prisoner of war in Russia, the idea of international understanding and peacekeeping was an important concern for him. As early as 1969 he invited many Russian scientists to the nuclear-physics conference at MPIK, and from the 1970s he promoted many collaborations between GSI and Russian institutes. He also pushed for Russia to become the largest member state in the GSI/FAIR project. The Russian invasion of Ukraine in February 2022 was therefore a great disappointment for him and for all of us.

Rudolf Bock was regularly present at GSI until his last days and continued to take an interest in current research and developments on campus. His advice and foresight will be sorely missed.

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