Leon Lederman 1922–2018
Leon Lederman, a pioneering US experimental particle physicist who shared the Nobel Prize in Physics for the discovery of the muon neutrino, passed away on 3 October at the age of 96. Lederman’s career spanned more than 60 years and had a major impact in putting the Standard Model of particle physics on empirical ground.
Lederman was born in New York City on 15 July 1922 to Russian–Jewish immigrant parents. He graduated from City College of New York with a degree in chemistry in 1943, but had already fallen under the influence of future physicists including Isaac Halpern and Martin Klein. After graduating he spent three years in the US Army, where he rose to the rank of 2nd lieutenant in the signal corps. In 1946 he entered the graduate school of physics at Columbia University, chaired by I I Rabi, and in 1951 he received his PhD in particle physics.
During the 1950s Lederman contributed to two major physics results: the discovery of the long-lived neutral K meson at Brookhaven National Laboratory’s 3 GeV Cosmotron in 1956; and, in 1957, the observation of parity violation in the pion–muon–electron decay chain at the Nevis 385 MeV synchrocyclotron at Columbia University. The latter experiment provided the first measurement of the muon magnetic moment, opening a path to the “g-2” experiment at CERN’s first accelerator, the synchrocyclotron. In 1958, shortly after he was promoted to professor, Lederman took his first sabbatical at CERN where he contributed to the organisation of the g-2 experiment. This programme lasted for almost two decades and involved many prominent CERN physicists, including Georges Charpak, Emilio Picasso, Francis Farley, Johannes Sens and Antonino Zichichi.
Lederman’s crowning achievement came in 1962 with the co-discovery of the muon neutrino at Brookhaven’s Alternating Gradient Synchrotron (AGS). For this work, he shared the 1988 Nobel Prize in Physics with Jack Steinberger and the late Melvin Schwartz “for the neutrino beam method and the demonstration of the doublet structure of the leptons through the discovery of the muon neutrino.” The experiment used a spark chamber to show that the neutrinos from beta decay and the neutrinos from muon decay were different, leading to the first direct observation of muon neutrinos and marking a key step in the understanding of weak interactions. Steinberger, who joined CERN six years after the muon-neutrino discovery and is now 97, has fond memories of his collaboration with Lederman. “What I remember about Leon is that we worked together at the same labs, at Nevis and at Brookhaven, and we got the Nobel Prize together, with Mel Schwartz. It was for a non-trivial experiment. He was a good friend. I’m very sad that he’s gone.”
At the end of the 1960s, in another experiment at the AGS, Lederman discovered the production of muon pairs with a continuous mass distribution in proton–nucleon collisions – an unexpected phenomenon that was soon interpreted as the result of quark–antiquark annihilation. As a follow-up to this experiment, in collaboration with physicists from CERN, Columbia and Rockefeller universities, Lederman proposed to study the production of electron–positron pairs at CERN’s Intersecting Storage Rings (ISR), which started operation in 1971. The experiment, known as R-103, discovered the production of neutral pions at high transverse momentum with a yield several orders of magnitude larger than expected. The result was again interpreted in terms of hard collisions between point-like proton constituents, demonstrating that these constituents also feel the strong interaction. “I had the privilege of working with Leon at Columbia in 1969–1970, when the R-103 experiment was proposed, and during the first years of ISR operation when he came to CERN,” says Luigi Di Lella of CERN. “I remember Leon as a physicist with enormous imagination, a boundless source of stimulating and often unconventional new ideas, which he always presented in a friendly and joyful atmosphere.”
As leader of the E70 and E288 experiments at Fermilab in the 1970s, Lederman also drove the effort that led to the discovery of the upsilon, the bound state of a bottom quark and antiquark, in 1977 (CERN Courier June 2017 p35). But his influence on the field of particle physics permeates far beyond his specific areas of research. In particular, he was a passionate advocate of education and worked with government and schools to create opportunities for students and better integrate physics into public education. He also had the rare quality to not take himself too seriously. Concerning the Higgs boson, he famously coined the term “God Particle” by using it in the title of his 1993 popular-science book The God Particle: If the Universe Is the Answer, What Is the Question? – though legend has it that he had originally wanted to call it the “God-dammed particle” because the Higgs boson was so difficult to find.
Lederman was director of the Nevis Laboratories at Columbia from 1961 to 1978. In 1979 he became director of Fermilab, where his vision and strategic planning led to the construction of the Tevatron (which operated from 1987 to 2011 and was the world’s highest-energy accelerator before the Large Hadron Collider came along). He stepped down as Fermilab director in 1989 and joined the faculty of the University of Chicago and, later, the Illinois Institute of Technology.
“Leon Lederman provided the scientific vision that allowed Fermilab to remain on the cutting edge of technology for more than 40 years,” says Nigel Lockyer, Fermilab’s current director. “Leon’s leadership helped to shape the field of particle physics, designing, building and operating the Tevatron and positioning the laboratory to become a world leader in accelerator and neutrino science. Leon had an immeasurable impact on the evolution of our laboratory and our commitment to future generations of scientists, and his legacy will live on in our daily work and our outreach efforts.”
- His friends and colleagues at CERN, with additional input from Fermilab.
Paul Kunz 1942–2018
After completing a PhD in physics at Princeton University, Kunz began his illustrious 35 year-long career at the Stanford Linear Accelerator Center (SLAC) in 1974 as a research associate in David Leith’s experimental physics Group B. As well as being an accomplished particle physicist, he quickly took an interest in one of the computing challenges facing experiments at the time – how to increase offline data-processing capability at a reasonable cost.
Using his deep understanding of computer architecture, software and hardware, he proposed a novel solution well beyond the norms of the time: the construction of a “farm” of interconnected processors each capable of executing IBM 370/168 instructions generated from standard FORTRAN code by an intermediate translator. In effect, the collection of interconnected computers in the farm would emulate, at a much lower cost, a single mainframe, distributing tasks to the individual processors, which became known as emulators. Each emulator would process entire events from particle interactions. Thus a simple parallel processing algorithm that did not require special programming or intricate modification to an experiment’s existing software was born.
After forming a small team at SLAC and building a prototype emulator known as the 168/E, Paul met CERN computer specialists David Lord and Adolfo Fucci. They immediately expressed a desire to join forces. In fact, they were looking for an online filter processor that would execute standard offline FORTRAN code to make a selection of events for fast analysis by CERN’s UA1 experiment, the so-called express line. Exhibiting his usual selfless interest in sharing ideas, Paul agreed to join forces, thereby establishing one of the first “real time” intercontinental collaborations by using the European Academic Research Network (EARN) and BITNET, courtesy of IBM.
The CERN/SLAC collaboration successfully constructed offline processing farms, notably for UA1. In parallel, one of the members of Paul’s original team, Hanoch Brafman, went on to build a complementary 370/E emulator at the Weizmann Institute of Science in Israel. Subsequently, the CERN/SLAC teams developed the next-generation emulator, the 3081/E, which was used by UA1 and the Large Electron–Positron Collider (LEP) experiments in online and offline environments. The farms were inherently extendable by simply adding processors, and are arguably the inspiration for today’s distributed offline computing facilities. The success of the emulator-based UA1 third-level trigger facility pioneered the use of a processor farm for the so-called high-level trigger system, which has since been employed by most collider experiments (at LEP, the Tevatron and the LHC), albeit with commercial processors.
In the 1990s, Paul turned his attention to the challenges of software development and became a guru and advocator of object-oriented programming. He was a passionate user of Steve Job’s NeXT computer and on an historic visit to CERN where he had regularly been giving courses on C++ programming, Paul immediately recognised the potential of the Web as demonstrated by Tim Berners-Lee and Robert Cailliau. Returning to SLAC, Paul not only installed the software on his NeXT, thereby establishing the first Web server in the US, he also connected it to the SPIRES database, giving the Web development team a “killer app”, which demonstrated the huge potential of their project.
In his personal life, Paul was a champion BMW autocross driver and president of the Bay Area BMW club, at which he was also, along with his wife, a driving instructor for teenagers. When travelling to CERN, he would often land in Frankfurt, hire a BMW, and take it for a spin round the Nuremberg ring. He loved Chinese food and liked nothing better than to enjoy dinner in one of the many Chinese restaurants in the SLAC area with visiting friends and colleagues, often speaking French with his unique accent, a legacy of time spent at CEA Saclay in the 1970s.
Paul Kunz was a computing visionary and pioneer, and a great communicator who loved to share his ideas with irrepressible energy.
Thank you for all the bytes and bites, Paul.
- Mick Storr, Adolfo Fucci and Paris Sphicas, assisted by other friends and colleagues of Paul.
Karlheinz Meier 1955–2018
Karlheinz’s career began at the University of Hamburg in Germany, where he studied physics. He completed his PhD there in 1984, with Gus Weber and Wulfrin Bartel as his supervisors, working for the JADE experiment at the PETRA electron–positron collider at DESY. During the following six years, he worked at CERN for the UA2 project, for two years as a CERN fellow and then as staff scientist. Returning to DESY in 1990, he joined the H1 collaboration. In 1992 he accepted a full professorship at Heidelberg University, where in 1994 he founded the Heidelberg ASIC Laboratory for Microelectronics and later, in 1999, the Kirchhoff Institute for Physics; during this period he also joined the ATLAS collaboration at CERN’s Large Hadron Collider (LHC). He was vice-rector at Heidelberg University from 2001 to 2004, chair of the European Committee for Future Accelerators (ECFA) from 2007 to 2009, and a member of the governing board of the German Physical Society (DPG) from 2009 to 2013. Within the Human Brain Project – a major 10 year-long effort harnessing cutting-edge research infrastructure for the benefit of neuroscience, computing and brain-related medicine – he initiated the European Institute for Neuromorphic Computing (EINC) at Heidelberg. Sadly, the completion of the facility cannot be witnessed by him anymore.
Karlheinz was an extremely enthusiastic, visionary and energetic scientist. He made fundamental contributions to the instrumentation and data analysis of large particle-physics experiments, especially concerning calorimeter systems. Early on, during his PhD, he developed advanced algorithms for identifying photons with the lead-glass calorimeter of JADE, an essential ingredient for his analysis of the inclusive production of photons, pions and η-mesons in multi-hadronic final states, but also for many studies of hadronisation and jet production, which JADE became famous for. Later, at CERN’s UA2 experiment, he participated in the first analyses of the newly discovered W and Z bosons.
Back at DESY, he was one of the advocates and initiators of the H1 scintillating fibre “spaghetti” calorimeter, which was decisive for precise measurements of the proton structure. In addition, his research group built another specialised backward calorimeter for H1, the VLQ; by analysing the VLQ data, he was able to refute the then theoretical predictions on special multi-gluon states, such as the odderon (CERN Courier April 2018 p9). Karlheinz recognised early on the need for developing highly integrated electronic circuits for experimental physics, and his group – together with colleagues from the Heidelberg ASIC Laboratory – developed the pre-processor system of the ATLAS level-1 calorimeter trigger, which played a pivotal role in the discovery of the Higgs boson.
Since 2001, Karlheinz became increasingly interested in fundamental questions related to the physics of complex systems and information processing, with a focus on the development of neuromorphic hardware for decoding the functioning of the brain. In contrast to normal, programme-oriented Turing machines, neuromorphic systems are extremely energy efficient, error tolerant and self-adaptive – just like the human brain. His research results received special international recognition through the Human Brain Project, which he initiated together with Henry Markram and Richard Frackowiak, and which was selected by the European Union in 2012 as one of two so-called Flagship Projects of European research funding.
Karlheinz was also exceptional in supervising and motivating young researchers. He was a highly gifted teacher, whose lectures and seminars were loved by his students. Through his renowned “Team-Anderthalb” 90-second movies on a wide variety of basic physics topics, he became known to the wider public; they are available, like many other of his lectures and talks, on YouTube.
Curiosity for the fundamental questions of physics and technological innovation were the two driving forces that accompanied Karlheinz throughout his research life. He not only contributed significantly to the expansion of our knowledge about nature, but also gave new impetus to technological development, especially in the field of microelectronics and computing. His commitment to both research and teaching was outstanding and special. His passion, humanity, humour, overall guidance and inspiration will be sorely missed and not forgotten.
- Siggi Bethke, Eckhard Elsen and Hans-Christian Schultz-Coulon, for his colleagues and friends worldwide.
Ferenc Niedermayer 1945–2018
Ferenc was born on 6 March 1945 in Budapest, Hungary. After obtaining a master’s degree from Leningrad State University in 1968, where he met his future wife Tamara, he received his PhD in 1971 from Eötvös University in Budapest. Following a three-month stay at CERN’s theory division in 1979, he worked at the Joint Institute for Nuclear Research in Dubna in 1980–1985 and at the University of California in San Diego in 1985–1986. Since 1989, he was a member of the Institute for Theoretical Physics at the University of Bern. In addition, he was a regular long-term visitor at the Max Planck Institute in Munich and at Eötvös University.
Ferenc was famous for possessing an extraordinarily broad knowledge of physics. During the early stages of his career, he worked on a variety of phenomenological topics, ranging from polarised lepton–hadron scattering to J/ψ production in hadron–nucleus collisions and to neutrino oscillations. When he came to Bern, Ferenc began to work in a more theoretical direction, particularly on the novel discipline of lattice field theory – the study of lattice discretisations of quantum field theories such as QCD. Over the years, he obtained numerous results of lasting value in this and related fields, some of them in collaboration with his old friends János Balog, Péter Hasenfratz and Peter Weisz. One famous result, which he obtained in collaboration with Hasenfratz and Michele Maggiore and made use of the intricate Wiener–Hopf technique, was the derivation of the mass gap of the two-dimensional O(3) model from its conjectured exact S-matrix. This model is often used as a prototypical solvable theory displaying many QCD-like features. Another celebrated result, which he achieved in collaboration with Hasenfratz and Victor Laliena and made use of the famous Ginsparg–Wilson relation, was the rigorous establishment of the Atiyah–Singer index theorem in a fully non-perturbative framework. This theorem plays a key role in the understanding of the vacuum structure and chiral symmetry properties of QCD.
After his retirement in 2010, Ferenc continued to work vigorously, both with new generations of students at Bern but in particular in a fruitful collaboration with Peter Weisz. This work continued and even accelerated after he received a diagnosis of liver cancer a few years ago. Ferenc talked openly about his illness. He always had a wonderful attitude towards work and life in general, and it was very inspiring to see how efficiently he spent his time.
Towards the end of his life, Ferenc visited Hungary to bid farewell to many old friends and colleagues. He died peacefully a few days after returning to Bern. Many of his friends and colleagues, both from Switzerland and Hungary, honoured a great scientist and a wonderful man at his funeral.
- His friends and colleagues.