Misplaced Pages

#151848

169-731: The Future Circular Collider ( FCC ) is a proposed particle accelerator with an energy significantly above that of previous circular colliders , such as the Super Proton Synchrotron , the Tevatron , and the Large Hadron Collider (LHC). The FCC project is considering three scenarios for collision types: FCC-hh, for hadron -hadron collisions, including proton -proton and heavy ion collisions, FCC-ee, for electron - positron collisions, and FCC-eh, for electron-hadron collisions. In FCC-hh, each beam would have

338-482: A 40-year search , and the construction of one of the world's most expensive and complex experimental facilities to date, CERN 's Large Hadron Collider , in an attempt to create Higgs bosons and other particles for observation and study. On 4 July 2012, the discovery of a new particle with a mass between 125 and 127  GeV/ c was announced; physicists suspected that it was the Higgs boson. Since then,

507-411: A klystron and a complex bending magnet arrangement which produces a beam of energy 6–30  MeV . The electrons can be used directly or they can be collided with a target to produce a beam of X-rays . The reliability, flexibility and accuracy of the radiation beam produced has largely supplanted the older use of cobalt-60 therapy as a treatment tool. In the circular accelerator, particles move in

676-410: A 3 km long waveguide, buried in a tunnel and powered by hundreds of large klystrons . It is still the largest linear accelerator in existence, and has been upgraded with the addition of storage rings and an electron-positron collider facility. It is also an X-ray and UV synchrotron photon source. Higgs boson This is an accepted version of this page The Higgs boson , sometimes called

845-666: A belief generally exists among physicists that there is likely to be "new" physics beyond the Standard Model , and the Standard Model will at some point be extended or superseded. The Higgs discovery, as well as the many measured collisions occurring at the LHC, provide physicists a sensitive tool to search their data for any evidence that the Standard Model seems to fail, and could provide considerable evidence guiding researchers into future theoretical developments. Below an extremely high temperature, electroweak symmetry breaking causes

1014-406: 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

1183-402: A circle until they reach enough energy. The particle track is typically bent into a circle using electromagnets . The advantage of circular accelerators over linear accelerators ( linacs ) is that the ring topology allows continuous acceleration, as the particle can transit indefinitely. Another advantage is that a circular accelerator is smaller than a linear accelerator of comparable power (i.e.

1352-426: A comprehensive theory for particle physics. In the late 1950s, Yoichiro Nambu recognised that spontaneous symmetry breaking , a process where a symmetric system becomes asymmetric, could occur under certain conditions. Symmetry breaking is when some variable that previously didn't affect the measured results ( it was originally a "symmetry" ) now does affect the measured results ( it's now "broken" and no longer

1521-553: A constant frequency by a RF accelerating power source, as the beam spirals outwards continuously. The particles are injected in the center of the magnet and are extracted at the outer edge at their maximum energy. Cyclotrons reach an energy limit because of relativistic effects whereby the particles effectively become more massive, so that their cyclotron frequency drops out of sync with the accelerating RF. Therefore, simple cyclotrons can accelerate protons only to an energy of around 15 million electron volts (15 MeV, corresponding to

1690-455: 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

1859-646: A full relativistic model, independently and almost simultaneously, by three groups of physicists: by François Englert and Robert Brout in August 1964; by Peter Higgs in October 1964; and by Gerald Guralnik , Carl Hagen , and Tom Kibble (GHK) in November 1964. Higgs also wrote a short, but important, response published in September 1964 to an objection by Gilbert , which showed that if calculating within

SECTION 10

#1732764654152

2028-696: A hole in the plate, the polarity is switched so that the plate now repels them and they are now accelerated by it towards the next plate. Normally a stream of "bunches" of particles are accelerated, so a carefully controlled AC voltage is applied to each plate to continuously repeat this process for each bunch. As the particles approach the speed of light the switching rate of the electric fields becomes so high that they operate at radio frequencies , and so microwave cavities are used in higher energy machines instead of simple plates. Linear accelerators are also widely used in medicine , for radiotherapy and radiosurgery . Medical grade linacs accelerate electrons using

2197-449: 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 Nb 3 Sn 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

2366-427: A linac would have to be extremely long to have the equivalent power of a circular accelerator). Depending on the energy and the particle being accelerated, circular accelerators suffer a disadvantage in that the particles emit synchrotron radiation . When any charged particle is accelerated, it emits electromagnetic radiation and secondary emissions . As a particle traveling in a circle is always accelerating towards

2535-514: A magnetic field which is fixed in time, but with a radial variation to achieve strong focusing , allows the beam to be accelerated with a high repetition rate but in a much smaller radial spread than in the cyclotron case. Isochronous FFAs, like isochronous cyclotrons, achieve continuous beam operation, but without the need for a huge dipole bending magnet covering the entire radius of the orbits. Some new developments in FFAs are covered in. A Rhodotron

2704-444: A major unanswered problem in physics. The six authors of the 1964 PRL papers , who received the 2010 J. J. Sakurai Prize for their work; from left to right: Kibble , Guralnik , Hagen , Englert , Brout ; right image: Higgs . Particle physicists study matter made from fundamental particles whose interactions are mediated by exchange particles – gauge bosons  – acting as force carriers . At

2873-508: A non-zero value (or vacuum expectation ) everywhere . This non-zero value could in theory break electroweak symmetry. It was the first proposal capable of showing how the weak force gauge bosons could have mass despite their governing symmetry, within a gauge invariant theory. Although these ideas did not gain much initial support or attention, by 1972 they had been developed into a comprehensive theory and proved capable of giving "sensible" results that accurately described particles known at

3042-452: A physical massive vector field [gauge bosons with mass]. This is what happens in superconductivity , a subject about which Anderson was (and is) one of the leading experts. [text condensed] The Higgs mechanism is a process by which vector bosons can acquire rest mass without explicitly breaking gauge invariance , as a byproduct of spontaneous symmetry breaking . Initially, the mathematical theory behind spontaneous symmetry breaking

3211-424: A potential intermediate step towards the realisation of the hadron facility. Clean experimental conditions have given ee 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

3380-432: A reactor to produce tritium . An example of this type of machine is LANSCE at Los Alamos National Laboratory . Electrons propagating through a magnetic field emit very bright and coherent photon beams via synchrotron radiation . It has numerous uses in the study of atomic structure, chemistry, condensed matter physics, biology, and technology. A large number of synchrotron light sources exist worldwide. Examples in

3549-459: A result of these failures, gauge theories began to fall into disrepute. The problem was symmetry requirements for these two forces incorrectly predicted the weak force's gauge bosons ( W and Z ) would have "zero mass" (in the specialized terminology of particle physics, "mass" refers specifically to a particle's rest mass ). But experiments showed the W and Z gauge bosons had non-zero (rest) mass. Further, many promising solutions seemed to require

SECTION 20

#1732764654152

3718-524: A scheduled update of the European Strategy for Particle Physics . 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

3887-454: 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 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

4056-426: A shorter distance in each orbit than they would in a classical cyclotron, thus remaining in phase with the accelerating field. The advantage of the isochronous cyclotron is that it can deliver continuous beams of higher average intensity, which is useful for some applications. The main disadvantages are the size and cost of the large magnet needed, and the difficulty in achieving the high magnetic field values required at

4225-904: A special class of light sources based on synchrotron radiation that provides shorter pulses with higher temporal coherence . A specially designed FEL is the most brilliant source of x-rays in the observable universe. The most prominent examples are the LCLS in the U.S. and European XFEL in Germany. More attention is being drawn towards soft x-ray lasers, which together with pulse shortening opens up new methods for attosecond science . Apart from x-rays, FELs are used to emit terahertz light , e.g. FELIX in Nijmegen, Netherlands, TELBE in Dresden, Germany and NovoFEL in Novosibirsk, Russia. Thus there

4394-474: A speed of roughly 10% of c ), because the protons get out of phase with the driving electric field. If accelerated further, the beam would continue to spiral outward to a larger radius but the particles would no longer gain enough speed to complete the larger circle in step with the accelerating RF. To accommodate relativistic effects the magnetic field needs to be increased to higher radii as is done in isochronous cyclotrons . An example of an isochronous cyclotron

4563-649: A straight line, or circular , using magnetic fields to bend particles in a roughly circular orbit. Magnetic induction accelerators accelerate particles by induction from an increasing magnetic field, as if the particles were the secondary winding in a transformer. The increasing magnetic field creates a circulating electric field which can be configured to accelerate the particles. Induction accelerators can be either linear or circular. Linear induction accelerators utilize ferrite-loaded, non-resonant induction cavities. Each cavity can be thought of as two large washer-shaped disks connected by an outer cylindrical tube. Between

4732-483: A symmetry ). In 1962 physicist Philip Anderson , an expert in condensed matter physics , observed that symmetry breaking played a role in superconductivity , and suggested it could also be part of the answer to the problem of gauge invariance in particle physics. Specifically, Anderson suggested that the Goldstone bosons that would result from symmetry breaking might instead, in some circumstances, be "absorbed" by

4901-452: A target or an external beam in beam "spills" typically every few seconds. Since high energy synchrotrons do most of their work on particles that are already traveling at nearly the speed of light c , the time to complete one orbit of the ring is nearly constant, as is the frequency of the RF cavity resonators used to drive the acceleration. In modern synchrotrons, the beam aperture is small and

5070-516: 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. CERN hosted an FCC study exploring the feasibility of different particle collider scenarios with the aim of significantly increasing the energy and luminosity compared to existing colliders. It aims to complement existing technical designs for proposed linear electron/positron colliders such as

5239-565: 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

Future Circular Collider - Misplaced Pages Continue

5408-402: Is 3 km (1.9 mi) long. SLAC was originally an electron – positron collider but is now a X-ray Free-electron laser . Linear high-energy accelerators use a linear array of plates (or drift tubes) to which an alternating high-energy field is applied. As the particles approach a plate they are accelerated towards it by an opposite polarity charge applied to the plate. As they pass through

5577-405: Is a circular magnetic induction accelerator, invented by Donald Kerst in 1940 for accelerating electrons . The concept originates ultimately from Norwegian-German scientist Rolf Widerøe . These machines, like synchrotrons, use a donut-shaped ring magnet (see below) with a cyclically increasing B field, but accelerate the particles by induction from the increasing magnetic field, as if they were

5746-413: Is a great demand for electron accelerators of moderate ( GeV ) energy, high intensity and high beam quality to drive light sources. Everyday examples of particle accelerators are cathode ray tubes found in television sets and X-ray generators. These low-energy accelerators use a single pair of electrodes with a DC voltage of a few thousand volts between them. In an X-ray generator, the target itself

5915-441: Is a manifestation of potential energy transferred to fundamental particles when they interact ("couple") with the Higgs field, which had contained that mass in the form of energy . The Higgs field is the only scalar (spin-0) field to be detected; all the other fundamental fields in the Standard Model are spin- ⁠ 1  / 2 ⁠ fermions or spin-1 bosons. According to Rolf-Dieter Heuer , director general of CERN when

6084-733: Is a power-intensive operation of cryogenic 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 . 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

6253-459: Is also very unstable, decaying into other particles almost immediately upon generation. The Higgs field is a scalar field with two neutral and two electrically charged components that form a complex doublet of the weak isospin SU(2) symmetry. Its " Sombrero potential " leads it to take a nonzero value everywhere (including otherwise empty space), which breaks the weak isospin symmetry of

6422-454: Is also very unstable, decaying into other particles almost immediately via several possible pathways. The Higgs field is a scalar field , with two neutral and two electrically charged components that form a complex doublet of the weak isospin SU(2) symmetry. Unlike any other known quantum field, it has a Sombrero potential . This shape means that below extremely high energies of about 159.5 ± 1.5  GeV such as those seen during

6591-509: Is an industrial electron accelerator first proposed in 1987 by J. Pottier of the French Atomic Energy Agency (CEA) , manufactured by Belgian company Ion Beam Applications . It accelerates electrons by recirculating them across the diameter of a cylinder-shaped radiofrequency cavity. A Rhodotron has an electron gun, which emits an electron beam that is attracted to a pillar in the center of the cavity. The pillar has holes

6760-422: Is commonly used for sterilization. Electron beams are an on-off technology that provide a much higher dose rate than gamma or X-rays emitted by radioisotopes like cobalt-60 ( Co) or caesium-137 ( Cs). Due to the higher dose rate, less exposure time is required and polymer degradation is reduced. Because electrons carry a charge, electron beams are less penetrating than both gamma and X-rays. Historically,

6929-560: Is more often used for accelerators that employ oscillating rather than static electric fields. Due to the high voltage ceiling imposed by electrical discharge, in order to accelerate particles to higher energies, techniques involving dynamic fields rather than static fields are used. Electrodynamic acceleration can arise from either of two mechanisms: non-resonant magnetic induction , or resonant circuits or cavities excited by oscillating radio frequency (RF) fields. Electrodynamic accelerators can be linear , with particles accelerating in

Future Circular Collider - Misplaced Pages Continue

7098-571: Is one of the electrodes. A low-energy particle accelerator called an ion implanter is used in the manufacture of integrated circuits . At lower energies, beams of accelerated nuclei are also used in medicine as particle therapy , for the treatment of cancer. DC accelerator types capable of accelerating particles to speeds sufficient to cause nuclear reactions are Cockcroft–Walton generators or voltage multipliers , which convert AC to high voltage DC, or Van de Graaff generators that use static electricity carried by belts. Electron beam processing

7267-573: 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. A high-energy hadron collider housed in

7436-402: Is still extremely popular today, with the electrostatic accelerators greatly out-numbering any other type, they are more suited to lower energy studies owing to the practical voltage limit of about 1 MV for air insulated machines, or 30 MV when the accelerator is operated in a tank of pressurized gas with high dielectric strength , such as sulfur hexafluoride . In a tandem accelerator

7605-417: Is strongly supported. The presence of the field, now confirmed by experimental investigation, explains why some fundamental particles have (a rest) mass , despite the symmetries controlling their interactions, implying that they should be "massless". It also resolves several other long-standing puzzles, such as the reason for the extremely short distance travelled by the weak force bosons, and, therefore,

7774-468: Is that the curvature of the particle trajectory is proportional to the particle charge and to the magnetic field, but inversely proportional to the (typically relativistic ) momentum . The earliest operational circular accelerators were cyclotrons , invented in 1929 by Ernest Lawrence at the University of California, Berkeley . Cyclotrons have a single pair of hollow D-shaped plates to accelerate

7943-633: Is that the magnetic field need only be present over the actual region of the particle orbits, which is much narrower than that of the ring. (The largest cyclotron built in the US had a 184-inch-diameter (4.7 m) magnet pole, whereas the diameter of synchrotrons such as the LEP and LHC is nearly 10 km. The aperture of the two beams of the LHC is of the order of a centimeter.) The LHC contains 16 RF cavities, 1232 superconducting dipole magnets for beam steering, and 24 quadrupoles for beam focusing. Even at this size,

8112-604: Is the PSI Ring cyclotron in Switzerland, which provides protons at the energy of 590 MeV which corresponds to roughly 80% of the speed of light. The advantage of such a cyclotron is the maximum achievable extracted proton current which is currently 2.2 mA. The energy and current correspond to 1.3 MW beam power which is the highest of any accelerator currently existing. A classic cyclotron can be modified to increase its energy limit. The historically first approach

8281-501: Is the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory . Particle accelerators can also produce proton beams, which can produce proton-rich medical or research isotopes as opposed to the neutron-rich ones made in fission reactors ; however, recent work has shown how to make Mo , usually made in reactors, by accelerating isotopes of hydrogen, although this method still requires

8450-412: 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

8619-412: The 1964 PRL symmetry breaking papers . All three groups reached similar conclusions and for all cases, not just some limited cases. They showed that the conditions for electroweak symmetry would be "broken" if an unusual type of field existed throughout the universe, and indeed, there would be no Goldstone bosons and some existing bosons would acquire mass . The field required for this to happen (which

SECTION 50

#1732764654152

8788-645: The Cockcroft–Walton generator and the Van de Graaff generator . A small-scale example of this class is the cathode-ray tube in an ordinary old television set. The achievable kinetic energy for particles in these devices is determined by the accelerating voltage , which is limited by electrical breakdown . Electrodynamic or electromagnetic accelerators, on the other hand, use changing electromagnetic fields (either magnetic induction or oscillating radio frequency fields) to accelerate particles. Since in these types

8957-946: The Diamond Light Source which has been built at the Rutherford Appleton Laboratory in England or the Advanced Photon Source at Argonne National Laboratory in Illinois , USA. High-energy X-rays are useful for X-ray spectroscopy of proteins or X-ray absorption fine structure (XAFS), for example. Synchrotron radiation is more powerfully emitted by lighter particles, so these accelerators are invariably electron accelerators. Synchrotron radiation allows for better imaging as researched and developed at SLAC's SPEAR . Fixed-Field Alternating Gradient accelerators (FFA)s , in which

9126-486: The Higgs mechanism , a way for some particles to acquire mass . All fundamental particles known at the time should be massless at very high energies, but fully explaining how some particles gain mass at lower energies had been extremely difficult. If these ideas were correct, a particle known as a scalar boson should also exist (with certain properties). This particle was called the Higgs boson and could be used to test whether

9295-476: The Higgs particle , 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. In the Standard Model, the Higgs particle is a massive scalar boson with zero spin , even (positive) parity , no electric charge , and no colour charge that couples to (interacts with) mass. It

9464-574: The International Linear Collider and the Compact Linear Collider . The study explores the potential of hadron and lepton 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

9633-502: The LEP and LHC , 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,

9802-591: The Nobel Prize in Physics in 2013 for their theoretical predictions. Although Higgs's name has come to be associated with this theory, several researchers between about 1960 and 1972 independently developed different parts of it. In the media, the Higgs boson has often been called the " God particle " after the 1993 book The God Particle by Nobel Laureate Leon Lederman . The name has been criticised by physicists, including Peter Higgs . Physicists explain

9971-443: The Standard Model through the mechanism of mass generation . As more precise measurements of its properties are made, more advanced extensions may be suggested or excluded. As experimental means to measure the field's behaviours and interactions are developed, this fundamental field may be better understood. If the Higgs field had not been discovered, the Standard Model would have needed to be modified or superseded. Related to this,

10140-451: The Sun . The Higgs field is responsible for this symmetry breaking. The Higgs field is pivotal in generating the masses of quarks and charged leptons (through Yukawa coupling) and the W and Z gauge bosons (through the Higgs mechanism). The Higgs field does not "create" mass out of nothing (which would violate the law of conservation of energy ), nor is the Higgs field responsible for

10309-783: The electromagnetic force and the weak nuclear force – and then to unify these interactions , were still unsuccessful. One known problem was that gauge invariant approaches, including non-abelian models such as Yang–Mills theory (1954), which held great promise for unified theories, also seemed to predict known massive particles as massless. Goldstone's theorem , relating to continuous symmetries within some theories, also appeared to rule out many obvious solutions, since it appeared to show that zero-mass particles known as Goldstone bosons would also have to exist that simply were "not seen". According to Guralnik , physicists had "no understanding" how these problems could be overcome. Particle physicist and mathematician Peter Woit summarised

SECTION 60

#1732764654152

10478-511: The electroweak interaction and, via the Higgs mechanism , gives a rest mass to all massive elementary particles of the Standard Model, including the Higgs boson itself. The existence of the Higgs field became the last unverified part of the Standard Model of particle physics, and for several decades was considered "the central problem in particle physics". Both the field and the boson are named after physicist Peter Higgs , who in 1964, along with five other scientists in three teams, proposed

10647-534: The electroweak interaction to manifest in part as the short-ranged weak force , which is carried by massive gauge bosons . In the history of the universe , electroweak symmetry breaking is believed to have happened at about 1 picosecond (10 s) after the Big Bang , when the universe was at a temperature 159.5 ± 1.5  GeV/ k B . This symmetry breaking is required for atoms and other structures to form, as well as for nuclear reactions in stars, such as

10816-486: The fundamental particles and forces of our universe in terms of the Standard Model – a widely accepted framework based on quantum field theory that predicts almost all known particles and forces aside from gravity with great accuracy. (A separate theory, general relativity , is used for gravity.) In the Standard Model, the particles and forces in nature (aside from gravity) arise from properties of quantum fields known as gauge invariance and symmetries . Forces in

10985-441: The inflaton responsible for this exponential expansion of the universe during the Big Bang . Such theories are highly tentative and face significant problems related to unitarity , but may be viable if combined with additional features such as large non-minimal coupling, a Brans–Dicke scalar, or other "new" physics, and they have received treatments suggesting that Higgs inflation models are still of interest theoretically. In

11154-407: The inflaton  – a hypothetical field suggested as the explanation for the expansion of space during the first fraction of a second of the universe (known as the " inflationary epoch "). Some theories suggest that a fundamental scalar field might be responsible for this phenomenon; the Higgs field is such a field, and its existence has led to papers analysing whether it could also be

11323-408: The speed of light in vacuum seems to give the identical result, whatever the location in time and space, and whatever the local gravitational field . In these kinds of theories, the gauge is an item whose value we can change. The fact that some changes leave the results we measure unchanged means it is a gauge invariant theory, and symmetries are the specific kinds of changes to the gauge which have

11492-467: The "Higgs Field", was hypothesized to exist throughout space, and to break some symmetry laws of the electroweak interaction , triggering the Higgs mechanism. It, therefore, would cause the W and Z gauge bosons of the weak force to be massive at all temperatures below an extremely high value. When the weak force bosons acquire mass, this affects the distance they can freely travel, which becomes very small, also matching experimental findings. Furthermore, it

11661-499: 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. The Large Hadron Collider at CERN with its High Luminosity upgrade

11830-530: 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". Particle accelerator Large accelerators include the Relativistic Heavy Ion Collider at Brookhaven National Laboratory in New York and

11999-614: 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

12168-794: The HL-LHC directly and provide a research programme of about 20 years beyond the middle of the 21st century. 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: 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. High-field superconducting magnets are

12337-435: 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 and CMS experiments while it could host two secondary experiments combined with injection as for the present LHC. The HE-LHC could succeed

12506-464: The Higgs boson suggest that our universe lies within a false vacuum of this kind, then it would imply – more than likely in many billions of years  – that the universe's forces, particles, and structures could cease to exist as we know them (and be replaced by different ones), if a true vacuum happened to nucleate . It also suggests that the Higgs self-coupling λ and its β λ function could be very close to zero at

12675-402: The Higgs boson was discovered, this existence proof of a scalar field is almost as important as the Higgs's role in determining the mass of other particles. It suggests that other hypothetical scalar fields suggested by other theories, from the inflaton to quintessence , could perhaps exist as well. There has been considerable scientific research on possible links between the Higgs field and

12844-403: The Higgs field and its properties has been extremely significant for many reasons. The importance of the Higgs boson largely is that it is able to be examined using existing knowledge and experimental technology, as a way to confirm and study the entire Higgs field theory. Conversely, proof that the Higgs field and boson did not exist would have also been significant. The Higgs boson validates

13013-432: The Higgs field and the presently observed vacuum energy density of the universe has also come under scientific study. As observed, the present vacuum energy density is extremely close to zero, but the energy densities predicted from the Higgs field, supersymmetry, and other current theories are typically many orders of magnitude larger. It is unclear how these should be reconciled. This cosmological constant problem remains

13182-558: The Higgs field does not actually resist particles, and the effect of mass is not caused by resistance. In the Standard Model, the Higgs boson is a massive scalar boson whose mass must be found experimentally. Its mass has been determined to be 125.35 ± 0.15 GeV/ c by CMS (2022) and 125.11 ± 0.11 GeV/ c by ATLAS (2023). It is the only particle that remains massive even at very high energies. It has zero spin , even (positive) parity , no electric charge , and no colour charge , and it couples to (interacts with) mass. It

13351-493: The Higgs field was the correct explanation. After a 40-year search , a subatomic particle with the expected properties was discovered in 2012 by the ATLAS and CMS experiments at the Large Hadron Collider (LHC) at CERN near Geneva , Switzerland. The new particle was subsequently confirmed to match the expected properties of a Higgs boson. Physicists from two of the three teams, Peter Higgs and François Englert , were awarded

13520-484: The LHC is limited by its ability to steer the particles without them going adrift. This limit is theorized to occur at 14 TeV. However, since the particle momentum increases during acceleration, it is necessary to turn up the magnetic field B in proportion to maintain constant curvature of the orbit. In consequence, synchrotrons cannot accelerate particles continuously, as cyclotrons can, but must operate cyclically, supplying particles in bunches, which are delivered to

13689-451: The LHC. Various analogies have been used to describe the Higgs field and boson, including analogies with well-known symmetry-breaking effects such as the rainbow and prism , electric fields , and ripples on the surface of water. Other analogies based on the resistance of macro objects moving through media (such as people moving through crowds, or some objects moving through syrup or molasses ) are commonly used but misleading, since

13858-465: The Planck scale, with "intriguing" implications, including theories of gravity and Higgs-based inflation. A future electron–positron collider would be able to provide the precise measurements of the top quark needed for such calculations. More speculatively, the Higgs field has also been proposed as the energy of the vacuum , which at the extreme energies of the first moments of the Big Bang caused

14027-435: The Standard Model are transmitted by particles known as gauge bosons . Gauge invariant theories are theories which have a useful feature, i.e.: some kinds of changes to the value of certain items do not make any difference to the outcomes or the measurements we make. For example: changing voltages in an electromagnet by +100 volts does not cause any change to the magnetic field it produces. Similarly, measuring

14196-516: The Standard Model provides an accurate description of particle physics up to extreme energies of the Planck scale , then it is possible to calculate whether the vacuum is stable or merely long-lived. A Higgs mass of 125–127 GeV/ c seems to be extremely close to the boundary for stability, but a definitive answer requires much more precise measurements of the pole mass of the top quark. New physics can change this picture. If measurements of

14365-443: The Standard Model, there exists the possibility that the underlying state of our universe – known as the "vacuum" – is long-lived, but not completely stable . In this scenario, the universe as we know it could effectively be destroyed by collapsing into a more stable vacuum state . This was sometimes misreported as the Higgs boson "ending" the universe. If the masses of the Higgs boson and top quark are known more precisely, and

14534-496: 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 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

14703-609: The Tevatron, LEP , and LHC may deliver the particle bunches into storage rings of magnets with a constant magnetic field, where they can continue to orbit for long periods for experimentation or further acceleration. The highest-energy machines such as the Tevatron and LHC are actually accelerator complexes, with a cascade of specialized elements in series, including linear accelerators for initial beam creation, one or more low energy synchrotrons to reach intermediate energy, storage rings where beams can be accumulated or "cooled" (reducing

14872-687: The U.S. are SSRL at SLAC National Accelerator Laboratory , APS at Argonne National Laboratory, ALS at Lawrence Berkeley National Laboratory , and NSLS-II at Brookhaven National Laboratory . In Europe, there are MAX IV in Lund, Sweden, BESSY in Berlin, Germany, Diamond in Oxfordshire, UK, ESRF in Grenoble , France, the latter has been used to extract detailed 3-dimensional images of insects trapped in amber. Free-electron lasers (FELs) are

15041-606: The Yang–Mills theory, that "considering the superconducting analog ... [t]hese two types of bosons seem capable of canceling each other out ... leaving finite mass bosons"), and in March 1964, Abraham Klein and Benjamin Lee showed that Goldstone's theorem could be avoided this way in at least some non-relativistic cases, and speculated it might be possible in truly relativistic cases. These approaches were quickly developed into

15210-436: The accuracy of its predictions led scientists to believe the theory might be true. By the 1980s, the question of whether the Higgs field existed, and therefore whether the entire Standard Model was correct, had come to be regarded as one of the most important unanswered questions in particle physics . The existence of the Higgs field became the last unverified part of the Standard Model of particle physics, and for several decades

15379-532: 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 W and Z bosons and the top quark , pinning down their interactions with an accuracy at least an order of magnitude better than today. The FCC-ee could collect 10 Z bosons, 10 W pairs, 10 Higgs bosons and 4 · 10 top-quark pairs per year. As

15548-494: The beam is handled independently by specialized quadrupole magnets , while the acceleration itself is accomplished in separate RF sections, rather similar to short linear accelerators. Also, there is no necessity that cyclic machines be circular, but rather the beam pipe may have straight sections between magnets where beams may collide, be cooled, etc. This has developed into an entire separate subject, called "beam physics" or "beam optics". More complex modern synchrotrons such as

15717-419: The beginning of the 1960s a number of these particles had been discovered or proposed, along with theories suggesting how they relate to each other, some of which had already been reformulated as field theories in which the objects of study are not particles and forces, but quantum fields and their symmetries . However, attempts to produce quantum field models for two of the four known fundamental forces –

15886-460: The center of the circle, it continuously radiates towards the tangent of the circle. This radiation is called synchrotron light and depends highly on the mass of the accelerating particle. For this reason, many high energy electron accelerators are linacs. Certain accelerators ( synchrotrons ) are however built specially for producing synchrotron light ( X-rays ). Since the special theory of relativity requires that matter always travels slower than

16055-493: 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

16224-613: The disks is a ferrite toroid. A voltage pulse applied between the two disks causes an increasing magnetic field which inductively couples power into the charged particle beam. The linear induction accelerator was invented by Christofilos in the 1960s. Linear induction accelerators are capable of accelerating very high beam currents (>1000 A) in a single short pulse. They have been used to generate X-rays for flash radiography (e.g. DARHT at LANL ), and have been considered as particle injectors for magnetic confinement fusion and as drivers for free electron lasers . The Betatron

16393-547: The effect of leaving measurements unchanged. Symmetries of this kind are powerful tools for a deep understanding of the fundamental forces and particles of our physical world. Gauge invariance is therefore an important property within particle physics theory. They are closely connected to conservation laws and are described mathematically using group theory . Quantum field theory and the Standard Model are both gauge invariant theories – meaning they focus on properties of our universe, demonstrating this property of gauge invariance and

16562-480: 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. Liquefaction of gas

16731-435: The electrons can pass through. The electron beam passes through the pillar via one of these holes and then travels through a hole in the wall of the cavity, and meets a bending magnet, the beam is then bent and sent back into the cavity, to another hole in the pillar, the electrons then again go across the pillar and pass though another part of the wall of the cavity and into another bending magnet, and so on, gradually increasing

16900-499: The electrons moving at nearly the speed of light in a relatively small radius orbit. In a linear particle accelerator (linac), particles are accelerated in a straight line with a target of interest at one end. They are often used to provide an initial low-energy kick to particles before they are injected into circular accelerators. The longest linac in the world is the Stanford Linear Accelerator , SLAC, which

17069-455: The energy and precision frontiers complementing studies for future linear machines. The discovery of a "light" Higgs boson 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

17238-461: The energy of the beam until it is allowed to exit the cavity for use. The cylinder and pillar may be lined with copper on the inside. Ernest Lawrence's first cyclotron was a mere 4 inches (100 mm) in diameter. Later, in 1939, he built a machine with a 60-inch diameter pole face, and planned one with a 184-inch diameter in 1942, which was, however, taken over for World War II -related work connected with uranium isotope separation ; after

17407-535: The eventual theory published there was still almost no wider interest. For example, Coleman found in a study that "essentially no-one paid any attention" to Weinberg's paper prior to 1971 and discussed by David Politzer in his 2004 Nobel speech.  – now the most cited in particle physics  – and even in 1970 according to Politzer, Glashow's teaching of the weak interaction contained no mention of Weinberg's, Salam's, or Glashow's own work. In practice, Politzer states, almost everyone learned of

17576-423: The existence of extra particles known as Goldstone bosons . But evidence suggested these did not exist either. This meant either gauge invariance was an incorrect approach, or something unknown was giving the weak force's W and Z bosons their mass, and doing it in a way that did not create Goldstone bosons. By the late 1950s and early 1960s, physicists were at a loss as to how to resolve these issues, or how to create

17745-623: The fact that many modern accelerators create collisions between two subatomic particles , rather than a particle and an atomic nucleus. Beams of high-energy particles are useful for fundamental and applied research in the sciences and also in many technical and industrial fields unrelated to fundamental research. There are approximately 30,000 accelerators worldwide; of these, only about 1% are research machines with energies above 1 GeV , while about 44% are for radiotherapy , 41% for ion implantation , 9% for industrial processing and research, and 4% for biomedical and other low-energy research. For

17914-464: The first picosecond (10 s) of the Big Bang , the Higgs field in its ground state takes less energy to have a nonzero vacuum expectation (value) than a zero value. Therefore in today's universe the Higgs field has a nonzero value everywhere (including otherwise empty space). This nonzero value in turn breaks the weak isospin SU(2) symmetry of the electroweak interaction everywhere. (Technically

18083-409: The first accelerators used simple technology of a single static high voltage to accelerate charged particles. The charged particle was accelerated through an evacuated tube with an electrode at either end, with the static potential across it. Since the particle passed only once through the potential difference, the output energy was limited to the accelerating voltage of the machine. While this method

18252-412: The first operational linear particle accelerator , the betatron , as well as the cyclotron . Because the target of the particle beams of early accelerators was usually the atoms of a piece of matter, with the goal being to create collisions with their nuclei in order to investigate nuclear structure, accelerators were commonly referred to as atom smashers in the 20th century. The term persists despite

18421-425: 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

18590-496: 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

18759-596: The largest accelerator, the Large Hadron Collider near Geneva, Switzerland, operated by CERN . It is a collider accelerator, which can accelerate two beams of protons to an energy of 6.5  TeV and cause them to collide head-on, creating center-of-mass energies of 13 TeV. There are more than 30,000 accelerators in operation around the world. There are two basic classes of accelerators: electrostatic and electrodynamic (or electromagnetic) accelerators. Electrostatic particle accelerators use static electric fields to accelerate particles. The most common types are

18928-411: The magnet aperture required and permitting tighter focusing; see beam cooling ), and a last large ring for final acceleration and experimentation. Circular electron accelerators fell somewhat out of favor for particle physics around the time that SLAC 's linear particle accelerator was constructed, because their synchrotron losses were considered economically prohibitive and because their beam intensity

19097-439: 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 systems. Such materials could also be complemented with

19266-412: The magnetic field does not cover the entire area of the particle orbit as it does for a cyclotron, so several necessary functions can be separated. Instead of one huge magnet, one has a line of hundreds of bending magnets, enclosing (or enclosed by) vacuum connecting pipes. The design of synchrotrons was revolutionized in the early 1950s with the discovery of the strong focusing concept. The focusing of

19435-401: The mass of all particles. For example, approximately 99% of the mass of baryons ( composite particles such as the proton and neutron ), is due instead to quantum chromodynamic binding energy , which is the sum of the kinetic energies of quarks and the energies of the massless gluons mediating the strong interaction inside the baryons. In Higgs-based theories, the property of "mass"

19604-588: The massless W and Z bosons . If so, perhaps the Goldstone bosons would not exist, and the W and Z bosons could gain mass , solving both problems at once. Similar behaviour was already theorised in superconductivity. In 1964, this was shown to be theoretically possible by physicists Abraham Klein and Benjamin Lee , at least for some limited ( non-relativistic ) cases. Following the 1963 and early 1964 papers, three groups of researchers independently developed these theories more completely, in what became known as

19773-424: 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

19942-481: The most basic inquiries into the dynamics and structure of matter, space, and time, physicists seek the simplest kinds of interactions at the highest possible energies. These typically entail particle energies of many GeV , and interactions of the simplest kinds of particles: leptons (e.g. electrons and positrons ) and quarks for the matter, or photons and gluons for the field quanta . Since isolated quarks are experimentally unavailable due to color confinement ,

20111-517: The need for a huge magnet of large radius and constant field over the larger orbit demanded by high energy. The second approach to the problem of accelerating relativistic particles is the isochronous cyclotron . In such a structure, the accelerating field's frequency (and the cyclotron resonance frequency) is kept constant for all energies by shaping the magnet poles so to increase magnetic field with radius. Thus, all particles get accelerated in isochronous time intervals. Higher energy particles travel

20280-610: The non-zero expectation value converts the Lagrangian 's Yukawa coupling terms into mass terms.) When this happens, three components of the Higgs field are "absorbed" by the SU(2) and U(1) gauge bosons (the " Higgs mechanism ") to become the longitudinal components of the now-massive W and Z bosons of the weak force . The remaining electrically neutral component either manifests as a Higgs boson, or may couple separately to other particles known as fermions (via Yukawa couplings ), causing these to acquire mass as well. Evidence of

20449-419: The ongoing exploration of thin-film NEG coating that is used in the internal surface of the copper vacuum chambers. 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

20618-455: The outer edge of the structure. Synchrocyclotrons have not been built since the isochronous cyclotron was developed. To reach still higher energies, with relativistic mass approaching or exceeding the rest mass of the particles (for protons, billions of electron volts or GeV ), it is necessary to use a synchrotron . This is an accelerator in which the particles are accelerated in a ring of constant radius. An immediate advantage over cyclotrons

20787-448: The particle has been shown to behave, interact, and decay in many of the ways predicted for Higgs particles by the Standard Model, as well as having even parity and zero spin , two fundamental attributes of a Higgs boson. This also means it is the first elementary scalar particle discovered in nature. By March 2013, the existence of the Higgs boson was confirmed, and therefore, the concept of some type of Higgs field throughout space

20956-412: The particles and a single large dipole magnet to bend their path into a circular orbit. It is a characteristic property of charged particles in a uniform and constant magnetic field B that they orbit with a constant period, at a frequency called the cyclotron frequency , so long as their speed is small compared to the speed of light c . This means that the accelerating D's of a cyclotron can be driven at

21125-411: The particles can pass through the same accelerating field multiple times, the output energy is not limited by the strength of the accelerating field. This class, which was first developed in the 1920s, is the basis for most modern large-scale accelerators. Rolf Widerøe , Gustav Ising , Leó Szilárd , Max Steenbeck , and Ernest Lawrence are considered pioneers of this field, having conceived and built

21294-477: 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. 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

21463-410: 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. The FCC study developed and evaluated three accelerator concepts for its conceptual design report. A lepton collider with centre-of-mass collision energies between 90 and 350 GeV is considered

21632-481: 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 (WIMPs) in the GeV – tens of TeV mass scale, and which could be in

21801-449: The potential is used twice to accelerate the particles, by reversing the charge of the particles while they are inside the terminal. This is possible with the acceleration of atomic nuclei by using anions (negatively charged ions ), and then passing the beam through a thin foil to strip electrons off the anions inside the high voltage terminal, converting them to cations (positively charged ions), which are accelerated again as they leave

21970-450: The radiation gauge, Goldstone's theorem and Gilbert's objection would become inapplicable. Higgs later described Gilbert's objection as prompting his own paper. Properties of the model were further considered by Guralnik in 1965, by Higgs in 1966, by Kibble in 1967, and further by GHK in 1967. The original three 1964 papers demonstrated that when a gauge theory is combined with an additional charged scalar field that spontaneously breaks

22139-429: 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

22308-479: 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 . The FCC-he collider would be both a high-precision Higgs factory and a powerful microscope that could discover new particles, study quark/gluon interactions, and examine possible further substructure of matter in

22477-405: 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

22646-416: The science of matter and the Standard Model (SM). The discovery of the Higgs boson completed the particle-related component of the Standard Model of Particle Physics , the theory that describes the laws governing most of the known Universe. Yet the Standard Model cannot explain several observations, such as: The LHC has inaugurated a new phase of detailed studies of the properties of the Higgs boson and

22815-434: The secondary winding in a transformer, due to the changing magnetic flux through the orbit. Achieving constant orbital radius while supplying the proper accelerating electric field requires that the magnetic flux linking the orbit be somewhat independent of the magnetic field on the orbit, bending the particles into a constant radius curve. These machines have in practice been limited by the large radiative losses suffered by

22984-435: 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 and Electroweak sector and broaden the exploration for different Dark Matter candidate particles complementing other approaches with neutrino beams, non-collider experiments and astrophysics experiments. The LHC has advanced

23153-571: The simplest available experiments involve the interactions of, first, leptons with each other, and second, of leptons with nucleons , which are composed of quarks and gluons. To study the collisions of quarks with each other, scientists resort to collisions of nucleons, which at high energy may be usefully considered as essentially 2-body interactions of the quarks and gluons of which they are composed. This elementary particle physicists tend to use machines creating beams of electrons, positrons, protons, and antiprotons , interacting with each other or with

23322-405: The simplest nuclei (e.g., hydrogen or deuterium ) at the highest possible energies, generally hundreds of GeV or more. The largest and highest-energy particle accelerator used for elementary particle physics is the Large Hadron Collider (LHC) at CERN , operating since 2009. Nuclear physicists and cosmologists may use beams of bare atomic nuclei , stripped of electrons, to investigate

23491-430: 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

23660-426: The speed of light in vacuum , in high-energy accelerators, as the energy increases the particle speed approaches the speed of light as a limit, but never attains it. Therefore, particle physicists do not generally think in terms of speed, but rather in terms of a particle's energy or momentum , usually measured in electron volts (eV). An important principle for circular accelerators, and particle beams in general,

23829-462: The state of research at the time: Yang and Mills work on non-abelian gauge theory had one huge problem: in perturbation theory it has massless particles which don't correspond to anything we see. One way of getting rid of this problem is now fairly well understood, the phenomenon of confinement realized in QCD , where the strong interactions get rid of the massless "gluon" states at long distances. By

23998-488: 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

24167-416: The structure, interactions, and properties of the nuclei themselves, and of condensed matter at extremely high temperatures and densities, such as might have occurred in the first moments of the Big Bang . These investigations often involve collisions of heavy nuclei – of atoms like iron or gold  – at energies of several GeV per nucleon . The largest such particle accelerator

24336-406: 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

24505-421: 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 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

24674-399: The symmetries which are involved. Quantum field theories based on gauge invariance had been used with great success in understanding the electromagnetic and strong forces , but by around 1960, all attempts to create a gauge invariant theory for the weak force (and its combination with the electromagnetic force, known together as the electroweak interaction ) had consistently failed. As

24843-415: The symmetry, the gauge bosons may consistently acquire a finite mass. In 1967, Steven Weinberg and Abdus Salam independently showed how a Higgs mechanism could be used to break the electroweak symmetry of Sheldon Glashow 's unified model for the weak and electromagnetic interactions , (itself an extension of work by Schwinger ), forming what became the Standard Model of particle physics. Weinberg

25012-436: 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

25181-658: The technological challenges inherent to the use of high-temperature superconductors (HTS) for accelerator magnets in the 20 T range. The beams that move in a circular accelerator lose a percentage of their energy due to synchrotron radiation : 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

25350-401: The terminal. The two main types of electrostatic accelerator are the Cockcroft–Walton accelerator , which uses a diode-capacitor voltage multiplier to produce high voltage, and the Van de Graaff accelerator , which uses a moving fabric belt to carry charge to the high voltage electrode. Although electrostatic accelerators accelerate particles along a straight line, the term linear accelerator

25519-404: The time, and which, with exceptional accuracy, predicted several other particles discovered during the following years . During the 1970s these theories rapidly became the Standard Model of particle physics. To allow symmetry breaking, the Standard Model includes a field of the kind needed to "break" electroweak symmetry and give particles their correct mass. This field, which became known as

25688-445: The universe to be a kind of featureless symmetry of undifferentiated, extremely high energy. In this kind of speculation, the single unified field of a Grand Unified Theory is identified as (or modelled upon) the Higgs field, and it is through successive symmetry breakings of the Higgs field, or some similar field, at phase transitions that the presently known forces and fields of the universe arise. The relationship (if any) between

25857-475: The very early sixties, people had begun to understand another source of massless particles: spontaneous symmetry breaking of a continuous symmetry. What Philip Anderson realized and worked out in the summer of 1962 was that, when you have both gauge symmetry and spontaneous symmetry breaking, the massless Nambu–Goldstone mode [which gives rise to Goldstone bosons] can combine with the massless gauge field modes [which give rise to massless gauge bosons] to produce

26026-573: The war it continued in service for research and medicine over many years. The first large proton synchrotron was the Cosmotron at Brookhaven National Laboratory , which accelerated protons to about 3  GeV (1953–1968). The Bevatron at Berkeley, completed in 1954, was specifically designed to accelerate protons to enough energy to create antiprotons , and verify the particle–antiparticle symmetry of nature, then only theorized. The Alternating Gradient Synchrotron (AGS) at Brookhaven (1960–)

26195-470: 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

26364-543: The weak force's extremely short range. As of 2018, in-depth research shows the particle continuing to behave in line with predictions for the Standard Model Higgs boson. More studies are needed to verify with higher precision that the discovered particle has all of the properties predicted or whether, as described by some theories, multiple Higgs bosons exist. The nature and properties of this field are now being investigated further, using more data collected at

26533-466: 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

26702-422: Was conceived and published within particle physics by Yoichiro Nambu in 1960 (and somewhat anticipated by Ernst Stueckelberg in 1938 ), and the concept that such a mechanism could offer a possible solution for the "mass problem" was originally suggested in 1962 by Philip Anderson, who had previously written papers on broken symmetry and its outcomes in superconductivity. Anderson concluded in his 1963 paper on

26871-506: Was considered "the central problem in particle physics". For many decades, scientists had no way to determine whether the Higgs field existed because the technology needed for its detection did not exist at that time. If the Higgs field did exist, then it would be unlike any other known fundamental field, but it also was possible that these key ideas, or even the entire Standard Model, were somehow incorrect. The hypothesised Higgs theory made several key predictions. One crucial prediction

27040-611: Was far from easy. In principle, it can be proved to exist by detecting its excitations , which manifest as Higgs particles (the Higgs boson ), but these are extremely difficult to produce and detect due to the energy required to produce them and their very rare production even if the energy is sufficient. It was, therefore, several decades before the first evidence of the Higgs boson could be found. Particle colliders , detectors, and computers capable of looking for Higgs bosons took more than 30 years ( c.  1980–2010 ) to develop. The importance of this fundamental question led to

27209-425: Was later realised that the same field would also explain, in a different way, why other fundamental constituents of matter (including electrons and quarks ) have mass. Unlike all other known fields, such as the electromagnetic field , the Higgs field is a scalar field , and has a non-zero average value in vacuum . There was not yet any direct evidence that the Higgs field existed, but even without direct proof,

27378-648: Was lower than for the unpulsed linear machines. The Cornell Electron Synchrotron , built at low cost in the late 1970s, was the first in a series of high-energy circular electron accelerators built for fundamental particle physics, the last being LEP , built at CERN, which was used from 1989 until 2000. A large number of electron synchrotrons have been built in the past two decades, as part of synchrotron light sources that emit ultraviolet light and X rays; see below. Some circular accelerators have been built to deliberately generate radiation (called synchrotron light ) as X-rays also called synchrotron radiation, for example

27547-403: Was possible in two papers covering massless, and then massive, fields. Their contribution, and the work of others on the renormalisation group  – including "substantial" theoretical work by Russian physicists Ludvig Faddeev , Andrei Slavnov , Efim Fradkin , and Igor Tyutin  – was eventually "enormously profound and influential", but even with all key elements of

27716-455: Was purely hypothetical at the time) became known as the Higgs field (after Peter Higgs , one of the researchers) and the mechanism by which it led to symmetry breaking became known as the Higgs mechanism . A key feature of the necessary field is that it would take less energy for the field to have a non-zero value than a zero value, unlike all other known fields, therefore, the Higgs field has

27885-447: 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, and

28054-433: Was that a matching particle , called the "Higgs boson", should also exist. Proving the existence of the Higgs boson would prove whether the Higgs field existed, and therefore finally prove whether the Standard Model's explanation was correct. Therefore, there was an extensive search for the Higgs boson , as a way to prove the Higgs field itself existed. Although the Higgs field would exist everywhere, proving its existence

28223-414: Was the synchrocyclotron , which accelerates the particles in bunches. It uses a constant magnetic field B {\displaystyle B} , but reduces the accelerating field's frequency so as to keep the particles in step as they spiral outward, matching their mass-dependent cyclotron resonance frequency. This approach suffers from low average beam intensity due to the bunching, and again from

28392-502: Was the first large synchrotron with alternating gradient, " strong focusing " magnets, which greatly reduced the required aperture of the beam, and correspondingly the size and cost of the bending magnets. The Proton Synchrotron , built at CERN (1959–), was the first major European particle accelerator and generally similar to the AGS. The Stanford Linear Accelerator , SLAC, became operational in 1966, accelerating electrons to 30 GeV in

28561-428: Was the first to observe that this would also provide mass terms for the fermions. At first, these seminal papers on spontaneous breaking of gauge symmetries were largely ignored, because it was widely believed that the (non-Abelian gauge) theories in question were a dead-end, and in particular that they could not be renormalised . In 1971–72, Martinus Veltman and Gerard 't Hooft proved renormalisation of Yang–Mills

#151848