The Synchro-Cyclotron, or Synchrocyclotron (SC), built in 1957, was

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 first accelerator. It was in circumference and provided for CERN's first experiments in

particle In the physical sciences, a particle (or corpuscle in older texts) is a small localized object which can be described by several physical or chemical properties, such as volume, density, or mass. They vary greatly in size or quantity, from s ...

and

nuclear physics Nuclear physics is the field of physics that studies atomic nuclei and their constituents and interactions, in addition to the study of other forms of nuclear matter. Nuclear physics should not be confused with atomic physics, which studies th ...

. It accelerated particles to energies up to . The foundation stone of CERN was laid at the site of the Synchrocyclotron by the first

Director-General A director general, general director or director-general (plural: ''directors general'', ''general directors'', ''directors-general'', ''director generals'' or ''director-generals'') is a senior executive officer, often the chief executive officer ...

of CERN,

Felix Bloch Felix Bloch (; ; 23 October 1905 – 10 September 1983) was a Swiss-American physicist who shared the 1952 Nobel Prize in Physics with Edward Mills Purcell "for their development of new methods for nuclear magnetic precision measurements and di ...

. After its remarkably long 33 years of service time, the SC was decommissioned in 1990. Nowadays it accepts visitors as an exhibition area in CERN.

Background

Synchrocyclotron A synchrocyclotron is a special type of cyclotron, patented by Edwin McMillan in 1952, in which the frequency of the driving RF electric field is varied to compensate for relativistic effects as the particles' velocity begins to approach the sp ...

(as a general idea) was invented by

Edwin McMillan Edwin Mattison McMillan (September 18, 1907 – September 7, 1991) was an American physicist credited with being the first to produce a transuranium element, neptunium. For this, he shared the 1951 Nobel Prize in Chemistry with Glenn Seaborg. ...

in 1945. Its main purpose is to accelerate charged particles like

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 ...

s and deutrons. The machine consists of two D-shaped hollow metal

electrode An electrode is an electrical conductor used to make contact with a nonmetallic part of a circuit (e.g. a semiconductor, an electrolyte, a vacuum or a gas). In electrochemical cells, electrodes are essential parts that can consist of a varie ...

s (called "dee"s) with a gap between them, connected to a

radio frequency Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around to around . This is roughly between the u ...

(RF) alternating

voltage Voltage, also known as (electrical) potential difference, electric pressure, or electric tension, is the difference in electric potential between two points. In a Electrostatics, static electric field, it corresponds to the Work (electrical), ...

source. These dees are placed on a plane in a way that their openings on the flat sides look at each other. The particles inside the Syncrocylotron can be accelerated from one dee to the other by the force produced by the

electrical field An electric field (sometimes called E-field) is a physical field that surrounds electrically charged particles such as electrons. In classical electromagnetism, the electric field of a single charge (or group of charges) describes their capaci ...

between dees. The particles accelerated between dees with this method are rotated by the

magnetic field A magnetic field (sometimes called B-field) is a physical field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular ...

created by two large magnets placed below and above the structure. The machine continues to accelerate particles by alternating the direction of the electrical field until they reach the maximum radius and then extracts them via a beam tube and sends them towards a target or another machine. Throughout the process, the frequency is being decreased to compensate

relativistic mass The word "mass" has two meanings in special relativity: ''invariant mass'' (also called rest mass) is an invariant quantity which is the same for all observers in all reference frames, while the relativistic mass is dependent on the velocity ...

increase due to the speed of the particles approaching the

speed of light The speed of light in vacuum, commonly denoted , is a universal physical constant exactly equal to ). It is exact because, by international agreement, a metre is defined as the length of the path travelled by light in vacuum during a time i ...

History

In late 1951, a UNESCO meeting about a new

Europe Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...

organization An organization or organisation (English in the Commonwealth of Nations, Commonwealth English; American and British English spelling differences#-ise, -ize (-isation, -ization), see spelling differences) is an legal entity, entity—such as ...

for

nuclear research Nuclear physics is the field of physics that studies atomic nuclei and their constituents and interactions, in addition to the study of other forms of nuclear matter. Nuclear physics should not be confused with atomic physics, which studies the ...

was held in Paris. In the meeting, the synchrocyclotron machine was proposed as an ideal solution for a medium-energy accelerator to use until they built a more powerful accelerator. Later in May 1952, in the first council meeting of the proposed organization,

Cornelis Bakker Cornelis Jan Bakker (11 March 1904 – 23 April 1960) was a Dutch physicist and second Director General of CERN. He was also a member of the Royal Netherlands Academy of Sciences. Biography Bakker studied physics at the University of Amsterd ...

was appointed as director of the Synchro-Cyclotron Study Group. After a month, in a report called Provisional Program of Synchro-Cyclotron Study Group, the group decided that they would need a design that could provide 600 MeV protons. The initial objective of the group stated as indicating the scope of the work to be done and studying and/or designing the necessary items. After preliminary studies, the first meeting of the SC study group was held in

Copenhagen Copenhagen ( ) is the capital and most populous city of Denmark, with a population of 1.4 million in the Urban area of Copenhagen, urban area. The city is situated on the islands of Zealand and Amager, separated from Malmö, Sweden, by the ...

in mid-June. Decisions made in the meeting included several trips to see similar machines around the world, making contacts to find appropriate companies that can build necessary pieces and preparing basic drawings of the machine. After a second meeting at Amsterdam in August, a progress report dated 1 October 1952 was prepared to be presented in the meeting of the

European Council for Nuclear Research 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 Gen ...

which was going to be held in Amsterdam in October. According to the report, the group aimed to finish its work in a year and a complete report to be presented to the European Council for Nuclear Research. A preliminary design drawing of the SC was attached to the report which stated that the work of the group was progressing "satisfactorily" and they were cooperating "adequately". The Synchro-Cyclotron Construction

In 1953, after a year of research, meetings and reports alike, the design of ''the Synchro-Cyclotron'' started. The construction of the machine began in 1954 on the site at

Meyrin Meyrin () is a Municipalities of Switzerland, municipality of the Canton of Geneva, Switzerland. The main site of CERN, the European particle physics research organisation, is in Meyrin. Meyrin was originally a small agricultural village until the ...

with the parts coming from all over Western Europe. In late 1955,

Wolfgang Gentner Wolfgang Gentner (23 July 1906 in Frankfurt am Main – 4 September 1980 in Heidelberg) was a German experimental nuclear physicist. Gentner received his doctorate in 1930 from the University of Frankfurt. From 1932 to 1935 he had a fellowship wh ...

became the director of the Synchro-Cyclotron Study Group, as former director Cornelis Bakker became the Director-General of CERN. The research program for the Synchrocyclotron started to be planned to be able to start experiments as soon as possible. The SC was ready to produce its first beam in August 1957, practically on the date foreseen. A press release by CERN on 16 August 1957, stated that the SC, as the third-largest accelerator of its type in the world, had started to work at its full energy. In late 1958, the Synchrocyclotron made its first important contribution to nuclear physics by the discovery of the rare

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 ...

decay Decay may refer to: Science and technology * Bit decay, in computing * Decay time (fall time), in electronics * Distance decay, in geography * Software decay, in computing Biology * Decomposition of organic matter * Mitochondrial decay, in g ...

of the

pion In particle physics, a pion (, ) or pi meson, denoted with the Greek alphabet, Greek letter pi (letter), pi (), is any of three subatomic particles: , , and . Each pion consists of a quark and an antiquark and is therefore a meson. Pions are the ...

particle. This discovery helped theorists a lot by proving that this decay really occurs. The Synchrocyclotron was used for an average of 135 hours per week during 1961; it ran continuously every day of the week except Mondays which were reserved for maintenance. The Synchrocyclotron was accelerating a jet of

s 54 times a second, up to a speed of approximately 240,000 kilometers per second (80% percent of the

). In May 1960, plans for an

isotope separator Isotope separation is the process of concentrating specific isotopes of a chemical element by removing other isotopes. The use of the nuclides produced is varied. The largest variety is used in research (e.g. in chemistry where atoms of "marker" nu ...

were published in Vienna. This isotope separator was built by CERN's Nuclear Chemistry Group (NCG) and used in measurements of production rates of

radionuclide A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess numbers of either neutrons or protons, giving it excess nuclear energy, and making it unstable. This excess energy can be used in one of three ...

s produced in the Synchrocyclotron. High production rates observed during these measurements proved that the SC was the ideal machine for experiments for on-line production of rare

isotope Isotopes are distinct nuclear species (or ''nuclides'') of the same chemical element. They have the same atomic number (number of protons in their Atomic nucleus, nuclei) and position in the periodic table (and hence belong to the same chemica ...

s. In April 1963, a group of physicists met at CERN to discuss for the

project. In late 1964, a formal proposal was submitted for the project and accepted by the CERN Director-General. In the same year, the Synchrocyclotron started to concentrate on

alone, leaving particle physics to a more powerful accelerator built in 1959, the

Proton Synchrotron The Proton Synchrotron (PS, sometimes also referred to as CPS) is a particle accelerator at CERN. It is CERN's first synchrotron, beginning its operation in 1959. For a brief period the PS was the world's highest energy particle accelerator. It ...

. In May 1966, the Synchrocyclotron was shut down for major modifications. Until mid-July, the capacity of the SC and its associated facilities were improved. Also, a new tunnel was constructed for an external proton

beamline In accelerator physics, a beamline refers to the trajectory of the beam of particles, including the overall construction of the path segment (guide tubes, diagnostic devices) along a specific path of an accelerator facility. This part is either ...

to the new underground hall for the new isotope separator. In 1967, it started supplying beams for the dedicated radioactive-ion-beam facility called

ISOLDE Iseult ( ), alternatively Isolde ( ) and other spellings, is the name of several characters in the legend of Tristan and Iseult. The most prominent is Iseult the Blonde, or Iseult of Ireland, the wife of Mark of Cornwall and the lover of Trista ...

, which still carries out research ranging from pure nuclear physics to

astrophysics Astrophysics is a science that employs the methods and principles of physics and chemistry in the study of astronomical objects and phenomena. As one of the founders of the discipline, James Keeler, said, astrophysics "seeks to ascertain the ...

and

medical physics Medical physics deals with the application of the concepts and methods of physics to the prevention, diagnosis and treatment of human diseases with a specific goal of improving human health and well-being. Since 2008, medical physics has been incl ...

. In 1969, preparations started to increase the beam intensity and improve the beam extraction efficiency of the SC. It was shut down in June 1973 for modifications. The highly improved machine started working again for physical research with its new name, SC2, in January 1975. In 1990, ISOLDE was transferred to the

Proton Synchrotron Booster The Proton Synchrotron Booster (PSB) is the first and smallest circular proton accelerator (a synchrotron) in the accelerator chain at the CERN injection complex, which also provides beams to the Large Hadron Collider. It contains four superi ...

, and the SC finally closed down after 33 years of service.

Converted to a CERN visitor point

Having served as storage facility since the 1990 shutdown, the SC and its building, the SC hall, were renovated in 2012-2013 to become an exhibition area for visitors, opening September 2013. The exhibition includes a multi-media show about the birth of CERN and the Synchrocyclotron. Using

projection mapping Projection mapping, similar to video mapping and spatial augmented reality, is a video projection, projection technique used to turn objects, often irregularly shaped, into display surfaces for video projection. The objects may be complex industr ...

technology, it displays simulations of the accelerating particles on the SC and demonstrates parts of it. SC physicicts—and CERN pioneers—Giuseppe and Maria Fidecaro are featured in the show. Some objects and tools which were used at the time the Synchrocyclotron was started are also in the hall for visitors to see.

Activities

Below is the list of some physics activities done at the SC. * Observation of the

decay of the

* Measurement of the

muon A muon ( ; from the Greek letter mu (μ) used to represent it) is an elementary particle similar to the electron, with an electric charge of −1 '' e'' and a spin of ''ħ'', but with a much greater mass. It is classified as a ...

anomalous

magnetic moment In electromagnetism, the magnetic moment or magnetic dipole moment is the combination of strength and orientation of a magnet or other object or system that exerts a magnetic field. The magnetic dipole moment of an object determines the magnitude ...

* Observation of the beta decay of the pion * Measurement of

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 ...

helicity from

muon decay A muon ( ; from the Greek letter mu (μ) used to represent it) is an elementary particle similar to the electron, with an electric charge of −1 '' e'' and a spin of ''ħ'', but with a much greater mass. It is classified as a lep ...

Muon capture Muon capture is the capture of a negative muon by a proton, usually resulting in production of a neutron and a neutrino, and sometimes a gamma photon. Muon capture by heavy nuclei often leads to emission of particles; most often neutrons, but c ...

hydrogen Hydrogen is a chemical element; it has chemical symbol, symbol H and atomic number 1. It is the lightest and abundance of the chemical elements, most abundant chemical element in the universe, constituting about 75% of all baryon, normal matter ...

* Muon channel * Muonic and pionic

x-rays An X-ray (also known in many languages as Röntgen radiation) is a form of high-energy electromagnetic radiation with a wavelength shorter than those of ultraviolet rays and longer than those of gamma rays. Roughly, X-rays have a wavelength ran ...

* Pion

scattering In physics, scattering is a wide range of physical processes where moving particles or radiation of some form, such as light or sound, are forced to deviate from a straight trajectory by localized non-uniformities (including particles and radiat ...

Nucleon In physics and chemistry, a nucleon is either a proton or a neutron, considered in its role as a component of an atomic nucleus. The number of nucleons in a nucleus defines the atom's mass number. Until the 1960s, nucleons were thought to be ele ...

scattering * Muon spin resonance for solid-state work: Metals,

semiconductor A semiconductor is a material with electrical conductivity between that of a conductor and an insulator. Its conductivity can be modified by adding impurities (" doping") to its crystal structure. When two regions with different doping level ...

polymer A polymer () is a chemical substance, substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeat unit, repeating subunits derived from one or more species of monomers. Due to their br ...

s *

Radioisotope A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess numbers of either neutrons or protons, giving it excess nuclear energy, and making it unstable. This excess energy can be used in one of three ...

s for medicine *

Nuclear spectroscopy Nuclear spectroscopy is a superordinate concept of methods that uses properties of a Nuclide, nucleus to probe material properties. By Radiation emission, emission or Absorption (electromagnetic radiation), absorption of radiation from the nucleus ...

* Far unstable nuclei and rare

decay mode Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is conside ...

s * Strength functions and statistical aspects of

beta decay In nuclear physics, beta decay (β-decay) is a type of radioactive decay in which an atomic nucleus emits a beta particle (fast energetic electron or positron), transforming into an isobar of that nuclide. For example, beta decay of a neutron ...

* Atomic physics: x-rays, optical spectra of

francium Francium is a chemical element; it has symbol Fr and atomic number 87. It is extremely radioactive; its most stable isotope, francium-223 (originally called '' actinium K'' after the natural decay chain in which it appears), has a half-l ...

* Implantation for

solid-state physics Solid-state physics is the study of rigid matter, or solids, through methods such as solid-state chemistry, quantum mechanics, crystallography, electromagnetism, and metallurgy. It is the largest branch of condensed matter physics. Solid-state phy ...

applications * Investigation of

nuclear structure Understanding the structure of the atomic nucleus is one of the central challenges in nuclear physics. Models The cluster model The cluster model describes the nucleus as a molecule-like collection of proton-neutron groups (e.g., alpha particl ...

: distribution of

nuclear charge In atomic physics, the effective nuclear charge of an electron in a multi-electron atom or ion is the number of elementary charges (e) an electron experiences by the nucleus. It is denoted by ''Z''eff. The term "effective" is used because the shi ...

s and

s *

Electromagnetic interaction In physics, electromagnetism is an interaction that occurs between particles with electric charge via electromagnetic fields. The electromagnetic force is one of the four fundamental forces of nature. It is the dominant force in the interacti ...

between the muon and the nucleus * Pionic atoms:

strong interaction In nuclear physics and particle physics, the strong interaction, also called the strong force or strong nuclear force, is one of the four known fundamental interaction, fundamental interactions. It confines Quark, quarks into proton, protons, n ...

effect * Pion double charge exchange * Pion production and absorption *

Spallation Spallation is a process in which fragments of material (spall) are ejected from a body due to impact or stress. In the context of impact mechanics it describes ejection of material from a target during impact by a projectile. In planetary p ...

fission Fission, a splitting of something into two or more parts, may refer to: * Fission (biology), the division of a single entity into two or more parts and the regeneration of those parts into separate entities resembling the original * Nuclear fissio ...

, fragmentation reactions with the production of radioactive species * Studies on nuclear masses, nuclear shapes, exotic decays * Radioactive detection of optical pump: discovery of shape staggering and shape coexistence in the Hg region * Rabi apparatus for the measurement of

spin Spin or spinning most often refers to: * Spin (physics) or particle spin, a fundamental property of elementary particles * Spin quantum number, a number which defines the value of a particle's spin * Spinning (textiles), the creation of yarn or thr ...

and magnetic moment *

Laser A laser is a device that emits light through a process of optical amplification based on the stimulated emission of electromagnetic radiation. The word ''laser'' originated as an acronym for light amplification by stimulated emission of radi ...

-induced

optical pumping Optical pumping is a process in which light is used to raise (or "pump") electrons from a lower energy level in an atom or molecule to a higher one. It is commonly used in laser construction to pump the active laser medium so as to achieve popu ...

* Collinear

laser spectroscopy Spectroscopy is the field of study that measures and interprets electromagnetic spectra. In narrower contexts, spectroscopy is the precise study of color as generalized from visible light to all bands of the electromagnetic spectrum. Spectrosc ...

* Resonance ionization

mass spectroscopy Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a ''mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is used ...

Background

History

Converted to a CERN visitor point

Activities

References

Further reading