Future Circular Collider
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The Future Circular Collider (FCC) is a proposed
particle accelerator A particle accelerator is a machine that uses electromagnetic fields to propel electric charge, charged particles to very high speeds and energies to contain them in well-defined particle beam, beams. Small accelerators are used for fundamental ...
with an energy significantly above that of previous circular
collider A collider is a type of particle accelerator that brings two opposing particle beams together such that the particles collide. Compared to other particle accelerators in which the moving particles collide with a stationary matter target, collid ...
s, such as the
Super Proton Synchrotron The Super Proton Synchrotron (SPS) is a particle accelerator of the synchrotron type at CERN. It is housed in a circular tunnel, in circumference, straddling the border of France and Switzerland near Geneva, Switzerland. History The SPS was d ...
, the
Tevatron The Tevatron was a circular particle accelerator (active until 2011) in the United States, at the Fermilab, Fermi National Accelerator Laboratory (called ''Fermilab''), east of Batavia, Illinois, and was the highest energy particle collider unt ...
, and the
Large Hadron Collider The Large Hadron Collider (LHC) is the world's largest and highest-energy particle accelerator. It was built by the CERN, European Organization for Nuclear Research (CERN) between 1998 and 2008, in collaboration with over 10,000 scientists, ...
(LHC). The FCC project is considering three scenarios for collision types: FCC-hh, for
hadron In particle physics, a hadron is a composite subatomic particle made of two or more quarks held together by the strong nuclear force. Pronounced , the name is derived . They are analogous to molecules, which are held together by the electri ...
-hadron collisions, including
proton A proton is a stable subatomic particle, symbol , Hydron (chemistry), H+, or 1H+ with a positive electric charge of +1 ''e'' (elementary charge). Its mass is slightly less than the mass of a neutron and approximately times the mass of an e ...
-proton and heavy ion collisions, FCC-ee, for
electron The electron (, or in nuclear reactions) is a subatomic particle with a negative one elementary charge, elementary electric charge. It is a fundamental particle that comprises the ordinary matter that makes up the universe, along with up qua ...
-
positron The positron or antielectron is the particle with an electric charge of +1''elementary charge, e'', a Spin (physics), spin of 1/2 (the same as the electron), and the same Electron rest mass, mass as an electron. It is the antiparticle (antimatt ...
collisions, and FCC-eh, for electron-hadron collisions. In FCC-hh, each beam would have a total energy of 560 MJ. With a centre-of-mass collision energy of 100 TeV (vs 14 TeV at LHC) the total energy value increases to 16.7 GJ. These total energy values exceed the present LHC by nearly a factor of 30.https://cds.cern.ch/record/2651300/files/CERN-ACC-2018-0058.pdf pg. 248, Beam Parameters gives GJ of total energy based on number of protons per bunch and number of bunches 0,400in FCC-hh: https://www.wolframalpha.com/input/?i=10400*1.0*(10%5E11)*100*(10%5E12)*1.602*(10%5E-19)
CERN The European Organization for Nuclear Research, known as CERN (; ; ), is an intergovernmental organization that operates the largest particle physics laboratory in the world. Established in 1954, it is based in Meyrin, western suburb of Gene ...
hosted an FCC study exploring the feasibility of different particle collider scenarios with the aim of significantly increasing the energy and
luminosity Luminosity is an absolute measure of radiated electromagnetic radiation, electromagnetic energy per unit time, and is synonymous with the radiant power emitted by a light-emitting object. In astronomy, luminosity is the total amount of electroma ...
compared to existing colliders. It aims to complement existing technical designs for proposed linear electron/positron colliders such as the
International Linear Collider The International Linear Collider (ILC) is a proposed linear particle accelerator. It is planned to have a collision energy of 500  GeV initially, with the possibility for a later upgrade to 1000 GeV (1 TeV). Although early propos ...
and the Compact Linear Collider. The study explores the potential of
hadron In particle physics, a hadron is a composite subatomic particle made of two or more quarks held together by the strong nuclear force. Pronounced , the name is derived . They are analogous to molecules, which are held together by the electri ...
and
lepton In particle physics, a lepton is an elementary particle of half-integer spin (Spin (physics), spin ) that does not undergo strong interactions. Two main classes of leptons exist: electric charge, charged leptons (also known as the electron-li ...
circular colliders, performing an analysis of infrastructure and operation concepts and considering the technology research and development programmes that are required to build and operate a future circular collider. A conceptual design report was published in early 2019, in time for a scheduled update of the European Strategy for Particle Physics.


Background

The CERN study was initiated as a direct response to the high-priority recommendation of the updated European Strategy for Particle Physics, published in 2013 which asked that "CERN should undertake design studies for accelerator projects in a global context, with emphasis on proton-proton and electron-positron high-energy frontier machines. These design studies should be coupled to a vigorous accelerator R&D programme, including high-field magnets and high-gradient accelerating structures, in collaboration with national institutes, laboratories and universities worldwide". The goal was to inform the next Update of the European Strategy for Particle Physics (2019–2020) and the wider physics community for the feasibility of circular colliders complementing previous studies for linear colliders as well as other proposal for particle physics experiments. The launch of the FCC study was also in line with the recommendations of the United States’ Particle Physics Project Prioritization Panel (P5) and of the International Committee for Future Accelerators (ICFA). The discovery of the Higgs boson at the LHC, together with the absence so far of any phenomena beyond the Standard Model in collisions at centre of mass energies up to 8 TeV, has triggered an interest in future circular colliders to push the energy and precision frontiers complementing studies for future linear machines. The discovery of a "light"
Higgs boson The Higgs boson, sometimes called the Higgs particle, is an elementary particle in the Standard Model of particle physics produced by the excited state, quantum excitation of the Higgs field, one of the field (physics), fields in particl ...
with a mass of 125 GeV revamped the discussion for a circular lepton collider that would allow detailed studies and precise measurement of this new particle. With the study of a new 80–100 km circumference tunnel (see also VLHC), that would fit in the Geneva region, it was realized that a future circular lepton collider could offer collision energies up to 400 GeV (thus allowing for the production of top quarks) at unprecedented luminosities. The design of FCC-ee (formerly known as TLEP (Triple-Large Electron-Positron Collider)) was combining the experience gained by LEP2 and the latest B-factories. Two main limitations to circular-accelerator performance are energy loss due to
synchrotron radiation Synchrotron radiation (also known as magnetobremsstrahlung) is the electromagnetic radiation emitted when relativistic charged particles are subject to an acceleration perpendicular to their velocity (). It is produced artificially in some types ...
, and the maximum value of magnetic fields that can be obtained in bending magnets to keep the energetic beams in a circular trajectory. Synchrotron radiation is of particular importance in the design and optimization of a circular lepton collider and limits the maximum energy that can be reached as the phenomenon depends on the mass of the accelerated particle. To address these issues a sophisticated machine design along with the advancement of technologies like accelerating (RF) cavities and high-field magnets are needed. Future "intensity and luminosity frontier" lepton colliders like those considered by the FCC study would enable the study with very high precision of the properties of the
Higgs boson The Higgs boson, sometimes called the Higgs particle, is an elementary particle in the Standard Model of particle physics produced by the excited state, quantum excitation of the Higgs field, one of the field (physics), fields in particl ...
, the W and Z bosons and the
top quark The top quark, sometimes also referred to as the truth quark, (symbol: t) is the most massive of all observed elementary particles. It derives its mass from its coupling to the Higgs field. This coupling is very close to unity; in the Standard ...
, pinning down their interactions with an accuracy at least an order of magnitude better than today. The FCC-ee could collect 1012 Z bosons, 108 W pairs, 106 Higgs bosons and 4 · 105 top-quark pairs per year. As a second step, an "energy frontier" collider at 100 TeV (FCC-hh) could be a "discovery machine" offering an eightfold increase compared to the current energy reach of the
LHC The Large Hadron Collider (LHC) is the world's largest and highest-energy particle accelerator. It was built by the European Organization for Nuclear Research (CERN) between 1998 and 2008, in collaboration with over 10,000 scientists, and ...
. The FCC integrated project, combining FCC-ee and FCC-hh, would rely on a shared and cost effective technical and organizational infrastructure, as was the case with LEP followed by LHC. This approach improves by several orders the sensitivity to elusive phenomena at low mass and by an order of magnitude the discovery reach for new particles at the highest masses. This will allow to uniquely map the properties of the
Higgs boson The Higgs boson, sometimes called the Higgs particle, is an elementary particle in the Standard Model of particle physics produced by the excited state, quantum excitation of the Higgs field, one of the field (physics), fields in particl ...
and
Electroweak In particle physics, the electroweak interaction or electroweak force is the unified description of two of the fundamental interactions of nature: electromagnetism (electromagnetic interaction) and the weak interaction. Although these two forc ...
sector and broaden the exploration for different Dark Matter candidate particles complementing other approaches with neutrino beams, non-collider experiments and astrophysics experiments.


Motivation

The LHC has advanced the science of
matter In classical physics and general chemistry, matter is any substance that has mass and takes up space by having volume. All everyday objects that can be touched are ultimately composed of atoms, which are made up of interacting subatomic pa ...
and the
Standard Model The Standard Model of particle physics is the Scientific theory, theory describing three of the four known fundamental forces (electromagnetism, electromagnetic, weak interaction, weak and strong interactions – excluding gravity) in the unive ...
(SM). The discovery of the
Higgs boson The Higgs boson, sometimes called the Higgs particle, is an elementary particle in the Standard Model of particle physics produced by the excited state, quantum excitation of the Higgs field, one of the field (physics), fields in particl ...
completed the particle-related component of the
Standard Model of Particle Physics The Standard Model of particle physics is the theory describing three of the four known fundamental forces (electromagnetic, weak and strong interactions – excluding gravity) in the universe and classifying all known elementary particles. It ...
, the theory that describes the laws governing most of the known Universe. Yet the Standard Model cannot explain several observations, such as: * evidence for
dark matter In astronomy, dark matter is an invisible and hypothetical form of matter that does not interact with light or other electromagnetic radiation. Dark matter is implied by gravity, gravitational effects that cannot be explained by general relat ...
, * prevalence of matter over
antimatter In modern physics, antimatter is defined as matter composed of the antiparticles (or "partners") of the corresponding subatomic particle, particles in "ordinary" matter, and can be thought of as matter with reversed charge and parity, or go ...
, * the
neutrino A neutrino ( ; denoted by the Greek letter ) is an elementary particle that interacts via the weak interaction and gravity. The neutrino is so named because it is electrically neutral and because its rest mass is so small ('' -ino'') that i ...
masses. The LHC has inaugurated a new phase of detailed studies of the properties of the Higgs boson and the way in which it interacts with the other SM particles. Future colliders with a higher energy and collision rate will largely contribute in performing these measurements, deepening our understanding of the Standard Model processes, test its limits and search for possible deviations or new phenomena that could provide hints for new physics. The Future Circular Collider (FCC) study develops options for potential high-energy frontier circular colliders at CERN for the post-LHC era. Among other things, it plans to look for dark matter particles, which account for approximately 25% of the energy in the observable universe. Though no experiment at colliders can probe the full range of dark matter (DM) masses allowed by astrophysical observations, there is a very broad class of models for
weakly interacting massive particles Weakly interacting massive particles (WIMPs) are hypothetical particles that are one of the proposed candidates for dark matter. There exists no formal definition of a WIMP, but broadly, it is an elementary particle which interacts via gravity an ...
(WIMPs) in the GeV – tens of TeV mass scale, and which could be in the range of the FCC. FCC could also lead the progress in precision measurements of Electroweak precision observables (EWPO). The measurements played a key role in the consolidation of the Standard Model and can guide future theoretical developments. Moreover, results from these measurements can inform data from astrophysical/cosmological observations. The improved precision offered by the FCC integrated programme increases the discovery potential for new physics. Moreover, FCC-hh will enable the continuation of the research programme in ultrarelativistic heavy-ion collisions from RHIC and LHC. The higher energies and luminosities offered by FCC-hh when operating with heavy-ions will open new avenues in the study of the collective properties of quarks and gluons. The FCC study also foresees an interaction point for electrons with protons (FCC-eh). These deep inelastic scattering measurements will resolve the parton structure with very high accuracy providing a per mille accurate measurement of the strong coupling constant. These results are essential for a programme of precision measurements and will further improve the sensitivity of search for new phenomena particularly at higher masses.


Scope

The FCC study originally put an emphasis on proton-proton (hadron or heavy-ion) high-energy collider that could also house an electron/positron (ee) high-intensity frontier collider as a first step. However after assessing the readiness of the different technologies and the physics motivation the FCC collaboration came up with the so-called FCC integrated programme foreseen as a first step FCC-ee with an operation time of about 10 years at different energy ranges from 90 GeV to 350 GeV, followed by FCC-hh with an operation time of about 15 years. The FCC collaboration has identified the technological advancements required for reaching the planned energy and intensity and performs technology feasibility assessments for critical elements of future circular colliders (i.e. high-field magnets, superconductors, Radio-frequency cavities cryogenic and vacuum system, power systems, beam screen system, a.o). The project needs to advance these technologies to meet the requirements of a post-LHC machine but also to ensure the large-scale applicability of these technologies that could lead to their further industrialization. The study also provides an analysis of the infrastructure and operation cost that could ensure the efficient and reliable operation of a future large-scale research infrastructure. Strategic R&D has been identified in the CDR over the coming years will concentrate on minimising construction costs and energy consumption, whilst maximising the socio-economic impact with a focus on benefits for industry and training. Scientists and engineers are also working on the detector concepts needed to address the physics questions in each of the scenarios (hh, ee, he). The work programme includes experiment and detector concept studies to allow new physics to be explored. Detector technologies will be based on experiment concepts, the projected collider performances and the physics cases. New technologies have to be developed in diverse fields such as cryogenics, superconductivity, material science, and computer science, including new data processing and data management concepts.


Colliders

The FCC study developed and evaluated three accelerator concepts for its conceptual design report.


FCC-ee (electron/positron)

A lepton collider with centre-of-mass collision energies between 90 and 350 GeV is considered a potential intermediate step towards the realisation of the hadron facility. Clean experimental conditions have given e+e storage rings a strong record both for measuring known particles with the highest precision and for exploring the unknown. More specifically, high luminosity and improved handling of lepton beams would create the opportunity to measure the properties of the Z, W, Higgs, and top particles, as well as the strong interaction, with increased accuracy. It can search for new particles coupling to the Higgs and electroweak bosons up to scales of Λ = 7 and 100 TeV. Moreover, measurements of invisible or exotic decays of the Higgs and Z bosons would offer discovery potential for dark matter or heavy neutrinos with masses below 70 GeV. In effect, the FCC-ee could enable profound investigations of electroweak symmetry breaking and open a broad indirect search for new physics over several orders of magnitude in energy or couplings. Realisation of an intensity-frontier lepton collider, FCC-ee, as a first step requires a preparatory phase of nearly 8 years, followed by the construction phase (all civil and technical infrastructure, machines and detectors including commissioning) lasting 10 years. A duration of 15 years is projected for the subsequent operation of the FCC-ee facility, to complete the currently envisaged physics programme. This makes a total of nearly 35 years for construction and operation of FCC-ee


FCC-hh (proton/proton and ion/ion)

A future energy-frontier hadron collider will be able to discover force carriers of new interactions up to masses of around 30 TeV if they exist. The higher collision energy extends the search range for dark matter particles well beyond the TeV region, while supersymmetric partners of quarks and gluons can be searched for at masses up to 15–20 TeV and the search for a possible substructure inside quarks can be extended down to distance scales of 10−21 m. Due to the higher energy and collision rate billions of Higgs bosons and trillions of top quarks will be produced, creating new opportunities for the study of rare decays and flavour physics. A hadron collider will also extend the study of Higgs and gauge boson interactions to energies well above the TeV scale, providing a way to analyse in detail the mechanism underlying the breaking of the electroweak symmetry. In heavy-ion collisions, the FCC-hh collider allows the exploration of the collective structure of matter at more extreme density and temperature conditions than before. Finally, FCC-eh adds to the versatility of the research programme offered by this new facility. With the huge energy provided by the 50 TeV proton beam and the potential availability of an electron beam with energy of the order of 60 GeV, new horizons open up for the physics of
deep inelastic scattering In particle physics, deep inelastic scattering is the name given to a process used to probe the insides of hadrons (particularly the baryons, such as protons and neutrons), using electrons, muons and neutrinos. It was first attempted in the 196 ...
. The FCC-he collider would be both a high-precision
Higgs factory A Higgs factory is a particle accelerator designed to produce Higgs bosons at a very high rate, allowing precision studies of this particle. A Higgs factory was identified as the highest future priority of particle physics in the 2020 European St ...
and a powerful microscope that could discover new particles, study quark/gluon interactions, and examine possible further substructure of matter in the world. In the FCC integrated scenario, the preparatory phase for an energy-frontier hadron collider, FCC-hh, will start in the first half of the FCC-ee operation phase. After the stop of FCC-ee operation, machine removal, limited civil engineering activities and an adaptation of the general technical infrastructure will take place, followed by FCC-hh machine and detector installation and commissioning, taking in total about 10 years. A duration of 25 years is projected for the subsequent operation of the FCC-hh facility, resulting in a total of 35 years for construction and operation of FCC-hh. The staged implementation provides a time window of 20–30 years for R&D on key technologies for FCC-hh. This could allow alternative technologies to be considered e.g. high-temperature superconducting magnets, and should lead to improved parameters and reduced implementation risks, compared to immediate construction after HL-LHC.


High-Energy LHC

A high-energy hadron collider housed in the same tunnel but using new FCC-hh class 16T dipole magnets could extend the current energy frontier by almost a factor of 2 (27 TeV collision energy) and delivers an integrated luminosity of at least a factor of 3 larger than the HL-LHC. This machine could offer a first measurement of the Higgs self-coupling and directly produce particles at significant rates at scales up to 12 TeV – almost doubling the HL-LHC discovery reach for new physics. The project reuses the existing LHC underground infrastructure and large parts of the injector chain at CERN. It is assumed that HE-LHC will accommodate two high-luminosity interaction-points (IPs) 1 and 5, at the locations of the present
ATLAS An atlas is a collection of maps; it is typically a bundle of world map, maps of Earth or of a continent or region of Earth. Advances in astronomy have also resulted in atlases of the celestial sphere or of other planets. Atlases have traditio ...
and
CMS CMS may refer to: Computing * Call management system * CMS-2, a programming language implemented for and used by the United States Navy * Code Morphing Software, a technology used by Transmeta * Collection management system for a museum coll ...
experiments while it could host two secondary experiments combined with injection as for the present LHC. The HE-LHC could succeed the HL-LHC directly and provide a research programme of about 20 years beyond the middle of the 21st century.


Technologies

As the development of a next generation particle accelerator requires new technology the FCC study has studied the equipment and machines that are needed for the realization of the project, taking into account the experience from past and present accelerator projects. The foundations for these advancements are being laid in focused R&D programmes: * a 16 tesla high-field accelerator magnet and related super-conductor research, * a 100 MW radiofrequency acceleration system that can efficiently transfer power from the electricity grid to the beams, * a highly efficient large-scale cryogenics infrastructure to cool down superconducting accelerator components and the accompanying refrigeration systems. Numerous other technologies from various fields (accelerator physics, high-field magnets, cryogenics, vacuum, civil engineering, material science, superconductors, ...) are needed for reliable, sustainable and efficient operation.


Magnet technologies

High-field superconducting magnets are a key enabling technology for a frontier hadron collider. To steer a 50 TeV beam over a 100 km tunnel, 16 tesla dipoles will be necessary, twice the strength of the magnetic field of the LHC. The main objectives of R&D on 16 T dipole magnets for a large particle accelerator is to prove that these types of magnets are feasible in accelerator quality and to ensure an adequate performance at an affordable cost. Therefore the goals are to push the conductor performance beyond present limits, to reduce the required "margin on the load line" with consequent reduction of conductor use and magnet size and the elaboration of an optimized magnet design maximizing performance with respect to cost. The magnet R&D aims to extend the range of operation of accelerator magnets based on low-temperature superconductors (LTS) up to 16 T and explore the technological challenges inherent to the use of high-temperature superconductors (HTS) for accelerator magnets in the 20 T range.


Superconducting radiofrequency cavities

The beams that move in a circular accelerator lose a percentage of their energy due to
synchrotron radiation Synchrotron radiation (also known as magnetobremsstrahlung) is the electromagnetic radiation emitted when relativistic charged particles are subject to an acceleration perpendicular to their velocity (). It is produced artificially in some types ...
: up to 5% every turn for electrons and positrons, much less for protons and heavy ions. To maintain their energy, a system of radiofrequency cavities constantly provides up to 50 MW to each beam. The FCC study has launched dedicated R&D lines on novel superconducting thin-film coating technology will allow RF cavities to be operated at higher temperature (CERN, Courier, April 2018), thereby lowering the electrical requirement for cryogenics, and reduce the required number of cavities thanks to an increase in the accelerating gradient. An ongoing R&D activity, carried out in close cooperation with the linear collider community, aims at raising the peak efficiency of klystrons from 65% to above 80%. Higher-temperature high-gradient Nb- Cu accelerating cavities and highly-efficient RF power sources could find numerous applications in other fields.


Cryogenics

Liquefaction of gas is a power-intensive operation of
cryogenic In physics, cryogenics is the production and behaviour of materials at very low temperatures. The 13th International Institute of Refrigeration's (IIR) International Congress of Refrigeration (held in Washington, DC in 1971) endorsed a univers ...
technology. The future lepton and hadron colliders would make intensive use of low-temperature superconducting devices, operated at 4.5 K and 1.8 K, requiring very large-scale distribution, recovery, and storage of cryogenic fluids. As a result, the cryogenic systems that have to be developed correspond to two to four times the presently deployed systems and require increased availability and maximum
energy efficiency Energy efficiency may refer to: * Energy efficiency (physics), the ratio between the useful output and input of an energy conversion process ** Electrical efficiency, useful power output per electrical power consumed ** Mechanical efficiency, a rat ...
. Any further improvements in cryogenics are expected to find wide applications in medical imaging techniques. The cryogenic beam vacuum system for an energy-frontier hadron collider must absorb an energy of 50 W per meter at cryogenic temperatures. To protect the magnet cold bore from the head load, the vacuum system needs to be resistant against electron cloud effects, highly robust, and stable under superconducting quench conditions. It should also allow fast feedback in the presence of impedance effects. New composite materials have to be developed to achieve these unique thermo-mechanical and electric properties for
collimation A collimated beam of light or other electromagnetic radiation has parallel rays, and therefore will spread minimally as it propagates. A laser beam is an archetypical example. A perfectly collimated light beam, with no divergence, would not disp ...
systems. Such materials could also be complemented with the ongoing exploration of thin-film NEG coating that is used in the internal surface of the copper vacuum chambers.


Collimation

A 100 TeV hadron collider requires efficient and robust collimators, as 100 kW of hadronic background is expected at the interaction points. Moreover, fast self-adapting control systems with sub-millimeter collimation gaps are necessary to prevent irreversible damage of the machine and manage the 8.3 GJ stored in each beam. To address these challenges, the FCC study searches for designs that can withstand the large energy loads with acceptable transient deformation and no permanent damage. Novel composites with improved thermo-mechanical and electric properties will be investigated in cooperation with the FP7 HiLumi LHC DS and EuCARD2 programmes.


Timescale

The Large Hadron Collider at CERN with its High Luminosity upgrade is the world's largest and most powerful particle accelerator and is expected to operate until 2036. A number of different proposals for a post-LHC research infrastructure in particle physics have been launched, including both linear and circular machines. The FCC study explores scenarios for different circular particle colliders housed in a new 100 km circumference tunnel, building on the tradition of the LEP and
LHC The Large Hadron Collider (LHC) is the world's largest and highest-energy particle accelerator. It was built by the European Organization for Nuclear Research (CERN) between 1998 and 2008, in collaboration with over 10,000 scientists, and ...
, which are both housed in the same 27 km circumference tunnel. A time-frame of 30 years is appropriate for the design and construction of a large accelerator complex and particle detectors. The experience from the operation of LEP and LHC and the opportunity to test novel technologies in the High Luminosity LHC provide a basis for assessing the feasibility of a post-LHC particle accelerator. In 2018, the FCC collaboration published the four volume Conceptual Design Report (CDR) as input to the next European Strategy for Particle Physics. The four volumes focus on: (a) "Vol. 1 Physics Opportunities"; (b) "Vol. 2 FCC-ee: The lepton collider"; (c) "Vol. 3 FCC-hh: The hadron collider"; and (d) "Vol. 4 The High-Energy LHC".


Organisation

The FCC study, hosted by CERN is an international collaboration of 135 research institutes and universities and 25 industrial partners from all over the world. The FCC study was launched following a response to the recommendation made in the update of the European Strategy for Particle Physics 2013, adopted by
CERN The European Organization for Nuclear Research, known as CERN (; ; ), is an intergovernmental organization that operates the largest particle physics laboratory in the world. Established in 1954, it is based in Meyrin, western suburb of Gene ...
's council. The study is governed by three bodies: the International Collaboration Board (ICB), the International Steering Committee (ISC), and the International Advisory Committee (IAC). The ICB reviews the resource needs of the study and finds matches within the collaboration. It so channels the contributions from the participants of the collaboration aiming at a geographically well-balanced and topically complementary network of contributions. The ISC is the supervisory and main governing body for the execution of the study and acts on behalf of the collaboration. The ISC is responsible for the proper execution and implementation of the decisions of the ICB, deriving and formulating the strategic scope, individual goals and the work programme of the study. Its work is facilitated by the Coordination Group, the main executive body of the project, which coordinates the individual work packages and performs the day-to-day management of the study. Finally, the IAC reviews the scientific and technical progress of the study and shall submit scientific and technical recommendations to the International Steering Committee to assist and facilitate major technical decisions.


Criticism

The FCC's proposed particle accelerator has been criticized for costs, with the cost for the energy-frontier hadron collider (FCC-hh) variant of this project projected to be over 20 billion US dollars. Physicist, author, content creator Sabine Hossenfelder criticized a relevant promotional video for outlining a wide range of open problems in physics, despite the fact that the accelerator will likely only have the potential to resolve a small part of them. She noted that () there is "no reason that the new physical effects, like particles making up dark matter, must be accessible at the next larger collider". Research from experimental data on the
cosmological constant In cosmology, the cosmological constant (usually denoted by the Greek capital letter lambda: ), alternatively called Einstein's cosmological constant, is a coefficient that Albert Einstein initially added to his field equations of general rel ...
,
LIGO The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a large-scale physics experiment and observatory designed to detect cosmic gravitational waves and to develop gravitational-wave observations as an astronomical tool. Prior to LIG ...
noise Noise is sound, chiefly unwanted, unintentional, or harmful sound considered unpleasant, loud, or disruptive to mental or hearing faculties. From a physics standpoint, there is no distinction between noise and desired sound, as both are vibrat ...
, and
pulsar timing Methods of detecting exoplanets usually rely on indirect strategies – that is, they do not directly Astrophotography, image the planet but deduce its existence from another signal. Any planet is an extremely faint light source compared to its ...
, suggests it's very unlikely that there are any new particles with masses much higher than those which can be found in the standard model or the LHC. However, other research has also suggested that
quantum gravity Quantum gravity (QG) is a field of theoretical physics that seeks to describe gravity according to the principles of quantum mechanics. It deals with environments in which neither gravitational nor quantum effects can be ignored, such as in the v ...
or
perturbative In quantum mechanics, perturbation theory is a set of approximation schemes directly related to mathematical perturbation for describing a complicated quantum system in terms of a simpler one. The idea is to start with a simple system for which ...
quantum field theory In theoretical physics, quantum field theory (QFT) is a theoretical framework that combines Field theory (physics), field theory and the principle of relativity with ideas behind quantum mechanics. QFT is used in particle physics to construct phy ...
will become strongly coupled before 1 PeV, leading to other new physics in the TeVs. Response to this criticism came both from within the physics community as well as from philosophers and historians of science who emphasized the exploratory potential of any future large-scale collider. A detailed physics discussion is included in the first volume of the FCC Conceptual Design Report. Gian Giudice, Head of CERN's Theoretical Physics Department wrote a paper on the "Future of High-Energy Colliders" while other commentary came from
Jeremy Bernstein Jeremy Bernstein (born December 31, 1929) is an American theoretical physicist and popular science writer. Early life Bernstein's parents, Philip S. Bernstein, a Reform rabbi, and Sophie Rubin Bernstein named him after the biblical Jeremiah, the ...
,
Lisa Randall Lisa Randall (born June 18, 1962) is an American theoretical physicist and Frank B. Baird, Jr. Professor of Science at Harvard University. Her research includes the fundamental forces of nature and dimensions of space. She studies the Standa ...
, James Beacham, Harry Cliff and Tommaso Dorigo among others. In a recent interview theorist for the
CERN Courier ''CERN Courier'' (or sometimes ''CERN Courier: International Journal of High Energy Physics'') is a bi-monthly trade magazine covering current developments in high-energy physics and related fields worldwide. It was established in 1959. From Octo ...
,
Nima Arkani-Hamed Nima Arkani-Hamed (; born April 5, 1972) is an Iranian-American-Canadian
described the concrete experimental goal for a post-LHC collider: "While there is absolutely no guarantee we will produce new particles, we will definitely stress test our existing laws in the most extreme environments we have ever probed. Measuring the properties of the Higgs, however, is guaranteed to answer some burning questions. ..A Higgs factory will decisively answer this question via precision measurements of the coupling of the Higgs to a slew of other particles in a very clean experimental environment." Moreover there has been some philosophical responses to this debate, most notably one from Michela Massimi who emphasised the exploratory potential of future colliders: "High-energy physics beautifully exemplifies a different way of thinking about progress, where progress is measured by ruling out live possibilities, by excluding with high confidence level (95%) certain physically conceivable scenarios and mapping in this way the space of what might be objectively possible in nature. 99.9% of the time this is how physics progresses and in the remaining time someone gets a Nobel Prize for discovering a new particle."


Studies for linear colliders

A high-luminosity upgrade of the LHC L-LHChas been approved to extend its operation lifetime into the mid-2030s. The upgrade will facilitate the detection of rare processes and improve statistical measurements. The Future Circular Collider study complements previous studies for linear colliders. The Compact Linear Collider (CLIC) was launched in 1985 at CERN. CLIC examines the feasibility of a high-energy (up to 3 TeV), high-luminosity lepton (electron/positron) collider. The
International Linear Collider The International Linear Collider (ILC) is a proposed linear particle accelerator. It is planned to have a collision energy of 500  GeV initially, with the possibility for a later upgrade to 1000 GeV (1 TeV). Although early propos ...
is a similar to CLIC project, planned to have a collision energy of 500 GeV. It presented its Technical Design Report in 2013. In 2013, the two studies formed an organisational partnership, the Linear Collider Collaboration (LCC) to coordinate and advance the global development work for a linear collider.


See also

* Compact Linear Collider – a post-LHC linear particle accelerator proposed at CERN *
International Linear Collider The International Linear Collider (ILC) is a proposed linear particle accelerator. It is planned to have a collision energy of 500  GeV initially, with the possibility for a later upgrade to 1000 GeV (1 TeV). Although early propos ...
– a proposed linear particle accelerator in Japan *
Circular Electron Positron Collider The Circular Electron Positron Collider (CEPC) is a proposed Chinese electron positron collider for experimenting on the Higgs boson. It would be the world's largest particle accelerator with a circumference of . CEPC was proposed by the Chinese ...
– a proposed circular collider in China *
Superconducting Super Collider The Superconducting Super Collider (SSC), nicknamed Desertron, was a particle accelerator complex under construction from 1991 to 1993 near Waxahachie, Texas, United States. Its planned ring circumference was with an energy of 20 TeV per proto ...
– a US circular collider project with a circumference of 87 km, abandoned in 1993


References


External links


Future Circular Collider Website
* {{authority control Particle physics facilities Proposed particle accelerators CERN particle accelerator studies