Peter Jenni

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Peter Jenni
Peter Jenni
Born (1948-04-17) 17 April 1948 (age 71)
Residence Arzier-Le Muids , Switzerland
Nationality Swiss
Known forFormer Spokesperson of the ATLAS Collaboration
Awards1998 Swiss Greinacher Prize
1999 Slovak gold medal Comenius University in Bratislava
2001 Czech Charles University in Prague memorial silver medal
2012 Czech Academy of Sciences Ernst Mach Honorary Medal
2012 Julius Wess Award Karlsruhe Institute of Technology
2012 Special Fundamental Physics Prize
2013 EPS HEPP Prize
2017 APS Panofsky Prize
Honorary Degrees from the University of Stockholm, the University of Copenhagen, the ETHZ, the Pontifical Catholic University of Chile, the University of Nova Gorica, the University of Bern, the Aix Marseille University, the Tbilisi State University, and the Weizmann Institute of Science
Scientific career
Fields Physics (Particle physics)
Institutions CERN, Albert-Ludwigs-Universität Freiburg

Peter Jenni, (born 17 April 1948) is an experimental particle physicist working at CERN. [1] He is best known as one of the "founding fathers" of the ATLAS experiment [2] at the CERN Large Hadron Collider together with a few other colleagues. He acted as spokesperson (project leader) of the ATLAS Collaboration until 2009. [3] ATLAS is a world-wide collaboration which started in 1992 [4] involving roughly 3,000 physicists at 183 institutions in 38 countries. [5] Jenni was directly involved in the experimental work leading to the discoveries of the W and Z bosons in the 1980s and the Higgs boson in 2012. [6] [7] He is (co-)author of about 900 publications in scientific journals.

CERN International organization which operates the worlds largest particle physics laboratory

The European Organization for Nuclear Research, known as CERN, is a European research organization that operates the largest particle physics laboratory in the world. Established in 1954, the organization is based in a northwest suburb of Geneva on the Franco–Swiss border and has 23 member states. Israel is the only non-European country granted full membership. CERN is an official United Nations Observer.

ATLAS experiment CERN LHC experiment

ATLAS is one of the seven particle detector experiments constructed at the Large Hadron Collider (LHC), a particle accelerator at CERN in Switzerland. The experiment is designed to take advantage of the unprecedented energy available at the LHC and observe phenomena that involve highly massive particles which were not observable using earlier lower-energy accelerators. ATLAS was one of the two LHC experiments involved in the discovery of the Higgs boson in July 2012. It was also designed to search for evidence of theories of particle physics beyond the Standard Model.

Large Hadron Collider particle collider

The Large Hadron Collider (LHC) is the world's largest and most powerful particle collider and the largest machine in the world. It was built by the European Organization for Nuclear Research (CERN) between 1998 and 2008 in collaboration with over 10,000 scientists and hundreds of universities and laboratories, as well as more than 100 countries. It lies in a tunnel 27 kilometres (17 mi) in circumference and as deep as 175 metres (574 ft) beneath the France–Switzerland border near Geneva.


Early life and education

Peter Jenni, Swiss, born in 1948, obtained his Diploma for Physics at the University of Bern in 1973 and his Doctorate at the Swiss Federal Institute of Technology in Zürich (ETHZ) in 1976. His thesis examined very small angle elastic scattering in the Coulomb-nuclear interference region. Peter Jenni is married and has two adult children.

Research career

Peter Jenni participated in CERN experiments at the Synchrocyclotron (1972/3), at the Proton Synchrotron (1974/6), and as ETHZ Research Associate at the Intersecting Storage Rings (ISR) (1976/7), the first high-energy hadron collider. From 1974 to summer 1976 he worked as a CERN Fellow in the group of M. Ferro-Luzzi. The group measured the Coulomb nuclear interference scattering of π±, K± and p± on hydrogen and deuterium in two experiments at the CERN PS. The measured real parts of the forward scattering amplitudes were used in dispersion relations. One of these measurements was the subject of the doctoral thesis (H. Hofer).

Synchrocyclotron special type of cyclotron

A synchrocyclotron is a special type of cyclotron, patented by Edwin McMillan, in which the frequency of the driving RF electric field is varied to compensate for relativistic effects as the particles' velocity begins to approach the speed of light. This is in contrast to the classical cyclotron, where this frequency is constant.

Intersecting Storage Rings Former CERN infrastructure

The ISR was a particle accelerator at CERN. It was the world's first hadron collider, and ran from 1971 to 1984, with a maximum center of mass energy of 62 GeV. From its initial startup, the collider itself had the capability to produce particles like the J/ψ and the upsilon, as well as observable jet structure; however, the particle detector experiments were not configured to observe events with large momentum transverse to the beamline, leaving these discoveries to be made at other experiments in the mid-1970s. Nevertheless, the construction of the ISR involved many advances in accelerator physics, including the first use of stochastic cooling, and it held the record for luminosity at a hadron collider until surpassed by the Tevatron in 2004.

Scattering general physical process where some forms of radiation, such as light, sound, or moving particles, are forced to deviate from a straight trajectory by one or more paths due to localized non-uniformities in the medium through which they pass

Scattering is a general physical process where some forms of radiation, such as light, sound, or moving particles, are forced to deviate from a straight trajectory by one or more paths due to localized non-uniformities in the medium through which they pass. In conventional use, this also includes deviation of reflected radiation from the angle predicted by the law of reflection. Reflections that undergo scattering are often called diffuse reflections and unscattered reflections are called specular (mirror-like) reflections.

From 1976 to 1977 Research Associate at the Swiss Federal Institute of Technology in Zürich (ETHZ) working in the CERN-ETH-Saclay collaboration R702 at the CERN Intersecting Storage Rings (P. Darriulat, B. Richter). The experiment covered studies on electron pair production, on e μ events as a signature for charmed particles, and on very high transverse momentum π0 production in pp reactions.

During 1978 and 1979, Research Associate at the Stanford Linear Accelerator Centre (SLAC), Stanford, USA, in B. Richter's group. Participated in the MARK II SLAC-LBL Berkeley experiment at the e+e– storage ring SPEAR. Mainly involved in the following physics analyses: two-photon reactions, meson form factors, and search for the charmed mesons.

SPEAR was a collider at the SLAC National Accelerator Laboratory. It began running in 1972, colliding electrons and positrons with an energy of 3 GeV. During the 1970s, experiments at the accelerator played a key role in particle physics research, including the discovery of the
meson, many charmonium states, and the discovery of the tau.

The first measurement of the two-photon widths of the η prime was giving further direct support to the quark model. In SLAC he also worked on operating the liquid-argon calorimeter for the MARK II experiment where his interest in high-performance calorimetry was developed.

Quark model

In particle physics, the quark model is a classification scheme for hadrons in terms of their valence quarks—the quarks and antiquarks which give rise to the quantum numbers of the hadrons. The quark model underlies "flavor SU(3)", or the Eightfold Way, the successful classification scheme organizing the large number of lighter hadrons that were being discovered starting in the 1950s and continuing through the 1960s. It received experimental verification beginning in the late 1960s and is a valid effective classification of them to date. The model was independently proposed by physicists Murray Gell-Mann, who dubbed them "quarks" in a concise paper, and George Zweig, who suggested "aces" in a longer manuscript. André Petermann also touched upon the central ideas from 1963 to 1965, without as much quantitative substantiation. Today, the model has essentially been absorbed as a component of the established quantum field theory of strong and electroweak particle interactions, dubbed the Standard Model.

Calorimeter instrument for measuring heat

A calorimeter is an object used for calorimetry, or the process of measuring the heat of chemical reactions or physical changes as well as heat capacity. Differential scanning calorimeters, isothermal micro calorimeters, titration calorimeters and accelerated rate calorimeters are among the most common types. A simple calorimeter just consists of a thermometer attached to a metal container full of water suspended above a combustion chamber. It is one of the measurement devices used in the study of thermodynamics, chemistry, and biochemistry.

He became a CERN staff member in 1980 working with the UA2 experiment at the Super Proton Synchrotron collider (major involvement in the discoveries of jets and the W and Z bosons). Worked on the design for the UA2 upgrade since 1984, with special motivation for missing transverse energy signatures. Project leader of the new end cap calorimeter constructed for the upgraded UA2 experiment. As from March 1987, also group leader of the CERN UA2 group. Coordinated calorimeter and trigger work for the upgraded UA2 experiment.

UA2 experiment CERN experiment leading to the discovery of W and Z bosons

The Underground Area 2 (UA2) experiment was a high-energy physics experiment at the Proton-Antiproton Collider — a modification of the Super Proton Synchrotron (SPS) — at CERN. The experiment ran from 1981 until 1990, and its main objective was to discover the W and Z bosons. UA2, together with the UA1 experiment, succeeded in discovering these particles in 1983, leading to the 1984 Nobel Prize in Physics being awarded to Carlo Rubbia and Simon van der Meer. The UA2 experiment also observed the first evidence for jet production in hadron collisions in 1981, and was involved in the searches of the top quark and of supersymmetric particles. Pierre Darriulat was the spokesperson of UA2 from 1981 to 1986, followed by Luigi Di Lella from 1986 to 1990.

Super Proton Synchrotron Particle accelerator at CERN

The Super Proton Synchrotron (SPS) is a particle accelerator of the synchrotron type at CERN. It is housed in a circular tunnel, 6.9 kilometres (4.3 mi) in circumference, straddling the border of France and Switzerland near Geneva, Switzerland.

The W and Z bosons are together known as the weak or more generally as the intermediate vector bosons. These elementary particles mediate the weak interaction; the respective symbols are
, and
. The W bosons have either a positive or negative electric charge of 1 elementary charge and are each other's antiparticles. The Z boson is electrically neutral and is its own antiparticle. The three particles have a spin of 1. The W bosons have a magnetic moment, but the Z has none. All three of these particles are very short-lived, with a half-life of about 3×10−25 s. Their experimental discovery was a triumph for what is now known as the Standard Model of particle physics.

Already during the UA2 time, strong interest in the physics and instrumentation at future colliders, in particular LHC. Early involvement as convener of the jet study group at the ECFA-CERN LHC workshop 1984 (Lausanne, Geneva), member of the advisory panel on the physics potential and the feasibility of experiments at the multi-TeV energies (La Thuile workshop 1987), and calorimetry overview at the ECFA study week on instrumentation technology for high-luminosity hadron colliders (Barcelona 1989).

He more and more shifted [8] to the Large Hadron Collider (LHC). From 1991 the main activities concentrated on tasks related to the informal spokespersonship first of a proto-Collaboration. Peter Jenni was involved in the early phases of the calorimeter R&D projects RD1 and RD3, during 1990–1992. In 1995, after formal approval of the ATLAS project, he was elected Spokesperson of the experiment, which today comprises some 3000 scientists representing 183 Institutions from 38 countries. He was re-elected several times and retired from this duty in February 2009, with Fabiola Gianotti as his successor. He retained however a strong involvement in the operation and physics of the experiment. [9]

After his retirement as a CERN Senior Research Staff end of April 2013, Peter Jenni has become a Guest Scientist and Honorary Professor with the Albert-Ludwigs-Universität Freiburg, keeping his full engagement with the ATLAS experiment.

In 2014 he has been elected as corresponding member of the Bavarian Academy of Sciences.

Advisory roles - Major physics committee involvement

- Final two years of the ISRC, CERN (1982 and 1983)
- Four years LEPC, CERN (1986 – 1990)
- Almost five years PRC of DESY as referee on the HERA experiment calorimetry, DESY, Hamburg, Germany (1984 – 1989)
- First few years of SSC PAC, Dallas, U.S. (1989 – 1991)
- Joint Institute for Nuclear Research (JINR) Dubna Scientific Council (since 2008)
- Served, and still serves, in numerous advisory boards at institute, national, and international levels, in particular for the future HEP projects
- During 2012 and 2013 he was strongly involved in shaping the scientific input with the Preparatory Group for the Update of the European Strategy for Particle Physics, personally motivated to promote CERN’s future at the high energy frontier.

Invited lectures and outreach

Peter Jenni is frequently invited to give public lectures on experimental particle physics at the LHC. Jenni is well known for his efforts to involve also physicists from countries that are not CERN member states in the construction of the ATLAS experiment. As a Spokesperson he frequently interacted with scientists from all five continents as well as with many funding agencies and science authorities. Thanks to his efforts many universities and institutes from a wide variety of countries became members of the ATLAS Collaboration making it a truly international experiment. [10] He often says that the biggest reward for him is to see how enthusiastic and motivated young people are about physics and he constantly tries to help future generations to get the same or even more opportunities in high energy physics. [11] [12] It is in this spirit that he, together with his ATLAS co-laureat of the Special Fundamental Physics Prize, Fabiola Gianotti, donated all prize money for educational and humanitarian purposes, and created the ATLAS PhD Award sponsoring PhD students. [13] He is also a founding member of the CERN and Society Foundation, an independent non-profit organization to support and promote the dissemination of the benefits of CERN through education and outreach, innovation and knowledge exchange, and culture and art. [14]


Related Research Articles

Particle physics Branch of physics

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Compact Muon Solenoid One of the two main purposes experiment at the CERNs Large Hadron Collider

The Compact Muon Solenoid (CMS) experiment is one of two large general-purpose particle physics detectors built on the Large Hadron Collider (LHC) at CERN in Switzerland and France. The goal of CMS experiment is to investigate a wide range of physics, including the search for the Higgs boson, extra dimensions, and particles that could make up dark matter.

Large Electron–Positron Collider

The Large Electron–Positron Collider (LEP) was one of the largest particle accelerators ever constructed.

Compact Linear Collider

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Lyn Evans Welsh physicist

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Higgs boson Elementary particle related to the Higgs field giving particles mass

The Higgs boson is an elementary particle in the Standard Model of particle physics, produced by the quantum excitation of the Higgs field, one of the fields in particle physics theory. It is named after physicist Peter Higgs, who in 1964, along with five other scientists, proposed the mechanism which suggested the existence of such a particle. Its existence was confirmed in 2012 by the ATLAS and CMS collaborations based on collisions in the LHC at CERN.

Joseph "Joe" Incandela is an American particle physicist, a professor of physics at the University of California, Santa Barbara and currently based at CERN, where he spent two years as the spokesperson for the Compact Muon Solenoid experiment at the Large Hadron Collider.

Search for the Higgs boson

The search for the Higgs boson was a 40-year effort by physicists to prove the existence or non-existence of the Higgs boson, first theorised in the 1960s. The Higgs boson was the last unobserved fundamental particle in the Standard Model of particle physics, and its discovery was described as being the "ultimate verification" of the Standard Model. In March 2013, the Higgs boson was officially confirmed to exist.

Guido Tonelli Particle physicist

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Tejinder Virdee British physicist

Sir Tejinder Singh Virdee,, is an experimental particle physicist and Professor of Physics at Imperial College London. He is best known for originating the concept of the Compact Muon Solenoid (CMS) with a few other colleagues and has been referred to as one of the 'founding fathers' of the project. CMS is a world-wide collaboration which started in 1991 and now has over 3500 participants from 45 countries.

Sau Lan Wu is a Chinese American particle physicist and the Enrico Fermi Distinguished Professor of Physics at the University of Wisconsin-Madison. She made important contributions towards the discovery of the J/psi particle, which provided experimental evidence for the existence of the charm quark, and the gluon, the vector boson of the strong force in the Standard Model of physics. Recently, her team located at the European Organization for Nuclear Research (CERN), using data collected at the Large Hadron Collider (LHC), was part of the international effort in the discovery of a boson consistent with the Higgs boson.

Ashutosh Kotwal

Ashutosh Vijay Kotwal is an American particle physicist of Indian origin. He is the Fritz London Professor of Physics at Duke University, and conducts research in particle physics related to W bosons and the Higgs boson and searches for new particles and forces.

James E. Brau

James E. Brau is an American physicist at the University of Oregon (UO) who conducts research on elementary particles and fields. He founded the Oregon experimental high energy physics group in 1988 and served as director of the UO Center for High Energy Physics from 1997–2016. Prior to joining the Oregon faculty, he served in the Air Force and held positions at the Stanford Linear Accelerator Center and the University of Tennessee. He is a fellow of both the American Physical Society and also the American Association for the Advancement of Science. In 2006 he was appointed the Philip H. Knight Professor of Natural Science, an endowed professorship.

Stephanie A. Majewski is an American physicist at the University of Oregon (UO) researching high energy particle physics at the CERN ATLAS experiment. She worked as a postdoctoral research associate at the Brookhaven National Laboratory prior to joining the faculty at UO in 2012. She was selected for the Early Career Research Program award of the U.S. Department of Energy (DOE), one of 35 scientists in all DOE-supported fields to receive this national honor in 2014.

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  1. "CERN official website".
  2. "Monica Dunford and Peter Jenni (2014) The ATLAS experiment. Scholarpedia, 9(10):32147".
  3. del Rosso, Antonella (May 2009). "ATLAS makes a smooth changeover at the top". CERN Courier. 49 (4): 31–32.
  4. del Rosso, Antonella (September 2008). "ATLAS: the making of a giant". CERN Courier.
  5. "ATLAS collaboration records". CERN Scientific Information Service. ATLAS collaboration. Archived from the original on 6 July 2011. Retrieved 2011-06-15.
  6. "The Higgs Boson 338 (2012)1558-1559".
  7. "M. Della Negra, P. Jenni, and T. S. Virdee, Journey in the Search for the Higgs Boson: The ATLAS and CMS Experiments at the Large Hadron Collider, Science 338 (2012) 1560-1568". Science.
  8. "P. Grannis and P. Jenni, The evolution of hadron-collider experiments, Physics Today 66(6),(38) 2013". Physics Today.
  9. "CERN Courier Article: Towards a Higgs boson: first steps in an incredible journey". CERN Courier. 22 May 2013.
  10. "CERN Courier Article: The strength of worldwide collaboration". CERN Courier. 23 July 2014.
  11. "The LegacyProject Interview 499".
  12. "PH Newsletter: Interview with Peter Jenni". PH newsletter. 3 June 2013.
  13. "Fundamental Physics Prize - News".
  14. "CERN and Society Foundation".
  15. "Greinacher Stiftung".
  16. "Julius Wess Award".
  17. "European Physical Society High Energy Physics Prize".
  18. "APS Panofsky Prize".