1. Cyclotron & Synchrotron
Designed by : Mona K h a l e g h y R a d
Advisor: Dr. A g h a m i r y
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2. Introduction Accelerators and Detectors
First Cyclotron : How came to the world and when?
What did scientists do with accelerators?
Other accelerators and detectors during these years
First Synchrotron : How came ,why and when?
Other recent accelerators and their goals and results
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3. For producing beams of energetic particles
Protons, antiprotons and light ions
heavy ions
electrons and positrons
(secondary) neutral beams (photons, neutrons, neutrinos)
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4. Accelerator Type of accelerators: 1) Fixed Target accelerators
2) Colliding beam accelerators :
a) Electrostatic
b) Cyclic : linear
circular
Betatron
Cyclotron
Synchrocyclotron
Synchrotron
Colliders
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5. Accelerator types electrostatic cascade Linear
battery, lightning, van de Graff, Pellatron: to about 30 MeV; for nuclear physics and isotope production
cascade
Cockcroft-Walton: to several MeV; cheap; for X-ray sources and injectors
Linear
RFQ
drift-tube(Wideroe, Alvarez):preaccelerators, LAMPF
Waveguide:electrons only(SLAC, NLC)
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6. Particle accelerators are used to investigate the structure of subatomic particles.
The motivation to strive for higher energy came from quantum mechanics, which describes particles as waves whose length is related to the momentum of particle by de Broglie’s expression : λ=h/p
Higher momentum brings shorter wavelengths and the capability to reveal the structure of matter with more details.
Discovery of smaller particles reveals more massive particles, which require, according to Einstein’s E=mc^2 , more and more energy to produce them. As particles are accelerated to energies many times their rest mass, momentum and energy will be calculated in terms of the special relativity. Although velocity saturates asymptotically – always below the speed of light-, momentum and energy continue to increase as particles are accelerated.
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7. As a basic principle, accelerators use powerful electric fields to push energy into a beam of charged particle. According to Lorentz force:
F=q (E +v *B)
one can see that particles gain energy only due to the electric field. Particles acquire an energy which is just their charge multiplied by the electric potential difference.
But, building up high-voltage electrostatic generators creates many difficulties because of the electrical breakdown, which becomes a serious problem above a few tens of KV.
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8. Characteristics of an accelerator:
Continuous or pulsed mode of operation;
The type of accelerated particles;
The maximum particle energy;
The intensity of the particle beam;
The particle energy resolution.
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9. Electrostatic accelerators:
Particles accelerated by a constant voltage difference
Example: Van de Graaff accelerators , which have Van de Graaff generator with tandem van de Graaff accelerator. (Fig)
The Cockroft-Walton generator is another kind of generators for electrostatic accelerators. (Fig)
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12. Cyclic accelerators: (Linear or Linac)
In linear accelerators, particles travel in a vacuum down a long, copper tube. The electrons ride waves made by wave generators called klystrons. Electromagnets keep the particles confined in a narrow beam. When the particle beam strikes a target at the end of the tunnel, various detectors record the events -- the subatomic particles and radiation released. These accelerators are huge, and are kept underground. An example of a linear accelerator is the linac at the Stanford Linear Accelerator Laboratory (SLAC) in California, which is about 1.8 miles (3 km) long.
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13. Alvarez Linac Wideroe Linac
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15. LINAC’s basic scheme
The idea of overcoming the voltage breakdown problem of a single stage of acceleration was to place a series of cylindrical electrodes one after another in a straight line to form linear accelerators, called LINACs, and use an alternative field.
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16. Charged particles enter on the left and are accelerated towards the first drift tube by an electric field. Once inside the drift tube, they are shielded from the field and drift through a constant velocity. When they arrive, at the next gap, the field accelerates them again until they reach the next drift tube. This continues with the particles picking up more and more energy in each gap, until they shoot out of the accelerator on the right. The drift tubes shield the particles for the length of time that the field would be decelerating.
But, to reach high energy, it would require extremely long linear accelerators.
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17. Diagram of linear accelerator
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18. Linac of CERN
CERN’s accelerator complex, one of the world’s complex scientific instruments, includes particle accelerators and colliders and handles beams of electrons, positrons, protons, antiprotons and ions. The achieved energies are about 100GeV in the Large Electron-Positron Collider LEP2, and will increase up to 7TeV in the future Large Hadron Collider LHC.
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22. Circular Accelerators
betatron
electrons only, cheap, portable, to ~500 MeV
cyclotron
Protons to ~500 MeV (TRIUMF, PSI)
Synchrotron
100 GeV electrons (LEP)
1 TeV protons and antiprotons (FNAL)
7 TeV protons (LHC)
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23. The following step was the cyclotron invention (1929), based on making a particle follow a circular path in a magnetic field through the same accelerating gap.
The balance between centripetal acceleration of motion in a circle and Lorentz’s force is:
evB =mv^2/r
The radius of the orbit in cyclotron is proportional to the velocity and the frequency of revolution: f=v/2r=eB/2m
For low energy particles, the revolution frequency of cyclotron is constant as far as the particle mass remains into the classic limit.
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24. Circular accelerators do essentially the same jobs as linacs
Circular accelerators do essentially the same jobs as linacs. However, instead of using a long linear track, they propel the particles around a circular track many times. At each pass, the magnetic field is strengthened so that the particle beam accelerates with each consecutive pass. When the particles are at their highest or desired energy, a target is placed in the path of the beam, in or near the detectors. Circular accelerators were the first type of accelerator invented in In fact, the first cyclotron (shown below) was only 4 inches (10 cm) in diameter
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25. cyclotron
Particles being accelerated move inside a vacuum chamber comprising two dees that are connected to a radio frequency (rf) generator with a frequency between Mhz. (Fig)
Cyclotron works with fixed frequency and it is possible until the mass of the particle approaches its rest mass.
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27. Animation cyclotron
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28. Lawrence's cyclotron used two D-shaped magnets (called Dee) separated by a small gap. The magnets produced a circular magnetic field. An oscillating voltage created an electric field across the gap to accelerate the particles (ions) each time around. As the particles moved faster, the radius of the their circular path became bigger until they hit the target on the outermost circle. Lawrence's cyclotron was effective, but could not reach the energies that modern circular accelerators do.
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29. Modern circular accelerators place klystrons and electromagnets around a circular copper tube to speed up particles. Many circular accelerators also have a short linac to accelerate the particles initially before entering the ring. An example of a modern circular accelerator is the Fermi National Accelerator Laboratory (Fermilab) in Illinois, which stretches almost 10 square miles (25.6 square km).
Left one is the first atom– smasher - cyclotron
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30. Lawrence
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31. Lawrence notes
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36. The first particle accelerator (cyclotron) developed by Ernest O
The first particle accelerator (cyclotron) developed by Ernest O. Lawrence in 1929
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38. Artist view of cyclotron
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39. Betatron Another electron accelerator (Fig)
It is now mainly used for : tumour therapy using either the electron beam or the X-rays radiated by the accelerated electrons as they circulated on their orbits, and for metal radiography using the X-radiation
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41. How Atom Smashers Work
Did you know that you have a type of particle accelerator in your house right now? In fact, you are probably reading this article with one! The cathode ray tube (CRT) of any TV or computer monitor is really a particle accelerator.
The CRT takes particles (electrons) from the cathode, speeds them up and changes their direction using electromagnets in a vacuum and then smashes them into phosphor molecules on the screen. The collision results in a lighted spot, or pixel, on your TV or computer monitor.
Particles are accelerated by electromagnetic waves inside the device, in much the same way as a surfer gets pushed along by the wave. The more energetic we can make the particles, the better we can see the structure of matter. It's like breaking the rack in a billiards game. When the cue ball (energized particle) speeds up, it receives more energy and so can better scatter the rack of balls (release more particles).
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42. Atom smasher
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44. TRIUMF (kind of cyclotron)
TR13 Cyclotron The TR13 is a small production cyclotron accelerating protons to 30 MeV (MeV = million electron volts). It was designed by TRIUMF staff, built by EBCO Technologies (Richmond, BC), and is owned by the University of British Columbia. Operated by TRIUMF staff, the TR13 is used in the research and production of radioisotopes for medical purposes. To the right (south) of the TR13
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45. Clean Room The clean room is kept dust-free by maintaining a positive atmospheric room pressure. This is accomplished by constantly pumping in filtered air such that the total room air volume is replaced every 4 minutes. In this dust-free environment TRIUMF technicians construct specialized equipment such as this module destined for the ATLAS particle detector at CERN, Switzerland. (TRIUMF's contribution to the ATLAS project consists of building 4 detector "wheels" at 32 modules/wheel - 2 "wheels" are placed at each end of the ATLAS tracking chamber.)
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46. Contraband Detection System TRIUMF has developed a new detection system that can "see" plastic explosives or illicit drugs in luggage and cargo. Even if the contraband is hidden, by scanning with gamma rays the Contraband Detection System (CDS) will provide 3-dimensional images of even small amounts of plastic explosives or illicit drugs
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47. Scintillators Scintillators are tested in the meson hall service annex (situated next to the meson hall extension). These plastic materials emit photons of visible light when they are struck by energetic particles or photons. In this display they are made to fluoresce by an ultraviolet lamp. Scintillators are used extensively at TRIUMF to detect particles, in conjunction with a photomultiplier tube which amplifies the light and converts it to an electric pulse. The scintillators are covered in black tape to exclude all outside light. Often complex-shaped light pipes are used to connect the scintillator to the photomultiplier, as the phototubes are too big to fit in the crowded area around the target. (Next: Meson Hall)
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48. Meson Hall Most of the protons extracted from the cyclotron are used to create an intense beam of pions (or "pi-mesons") for use in the meson hall. In an average of 26 billionths of a second the pions decay into muons (which last, on average, for 2.2 millionths of a second). Separating the pion beam into different "beam lines" allows several pion/muon experiments to be performed simultaneously. Looking down two stories to the meson hall floor below, we see some of the individual beam lines emerging from the yellow shielding blocks.
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49. Concrete Blocks This first thing you will notice about the meson hall is the number of huge yellow blocks, piled up like a giant brick wall, along the south side. As you may have guessed, these "bricks" are made of concrete. Concrete is used as a shielding material wherever possible. It is reasonably effective and inexpensive. Also, the modular blocks are easily moved, by one of the twin 50-ton travelling overhead cranes, for maintenance or changing of beam line elements. The whole building contains 45,000 tonnes of concrete shielding to absorb the radiation given off by the cyclotron and beam lines.
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50. Cave Interlocks To visit one of the experimental areas, we walk down two flights of stairs. The area around the beam line where the experiment is mounted is known as a "cave". A cave is typically surrounded by shielding blocks and secured with an interlock system, which prevents beam delivery to the beam line when the cave door is open. Experimenters set up their equipment, including particle detectors, and must leave before the control room personnel allow the beam to enter the experimental area.
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51. RMC Counting Room Electric signals from the photomultipliers, drift chambers and other particle detectors are brought in here and processed electronically before being sent to the data acquisition computer. (RMC stand for radiative muon capture - an ongoing experiment.)
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52. RMC Data Acquisition The physics data acquisition is controlled from this workstation. Data is sorted and formatted, then written to 8mm videotape for later analysis. Data may also be processed immediately to give a visual reconstruction of the particle tracks for each "event".
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53. Proton Therapy Also located in the meson hall, next to the cyclotron vault, is the proton therapy facility. This facility uses a finely tuned proton beam from the cyclotron to treat cancerous growths on the back of a patient's eye, called choroidal melanomas. In this facility we see the specialized treatment chair and alignment methods used by the B.C. Cancer Agency medical team to focus the proton beam accurately into the tumour. (Next: we visit the roof of the cyclotron vault - 12 metres above the meson hall floor.)
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54. ISIS: Ion Source Injection System Negatively charged hydrogen ions are transported through this beam pipe and injected into the centre of the cyclotron. This delivery system includes electrostatic steering elements and an ultra-high vacuum system. At the far end and to the right are the four ion sources.
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55. Ion Sources There are four different ion sources
Ion Sources There are four different ion sources. Which is used depends on the type of proton beam the experimenters require. Sources 1 and 3 produce unpolarized hydrogen ions. Sources 2 and 4 produce polarized hydrogen ions. Source 2 uses an older method and is not used much. Source 4 uses lasers to generate the polarized ions and is called an optically pumped polarized ion source (OPPIS) - TRIUMF is at the leading edge in the development of this technology.
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56. Entry to the Cyclotron Vault Upon entering the vault all persons must put on overshoes. On exiting, the overshoes are removed and a frisker is used to check for radioactive contamination. It is a good idea to leave any credit cards, etc. at this station since the intense magnetic field from the main cyclotron magnet will delete their megnetic information
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57. Underneath the Cyclotron Accelerator Chamber Looking underneath the cyclotron accelerator chamber we first notice a yellow magnet sector. The magnetic field here is so strong it disrupts the electronics in our camera equipment. The pictures shown here were taken in manual mode. The magnetic field presents a severe safety hazard, since steel tools and even heavy compressed gas bottles are attracted with great force to the magnets
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58. Tie Rods Another noticeable feature is the tie rods on the underside of the cyclotron tank. During operation, the inside of the tank is almost a perfect vacuum. The rods, present both below and above the accelerator chamber, prevent it from collapsing due to atmospheric pressure. See Cyclotron Facts for more details
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59. The Cyclotron Superstructure The superstructure which surrounds the cyclotron supports the magnets (total weight: 4000 tonnes) and prevents the accelerator chamber from imploding due to atmospheric pressure. Beside the giant cyclotron we see stairs leading to the top of the structure. Situated above the stairs is the moveable crane used for maintenance
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60. Top of the Cyclotron From the top of the stairs, we have a good view of the cyclotron. Twenty-four jacks, evenly-spaced around the cyclotron, have been used to carefully lift the lid of the chamber (after releasing the vacuum) and the upper magnet (2,000 tonnes) to a height of 1.2 m (4 ft). To eliminate any warping of the accelerator chamber, computers are used to control the rate of lift of each jack to within 1 mm of each other (the thickness of a dime!).
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61. The Vacuum Tank About twice a year the cyclotron is shut down for maintenance. At these times the accelerator chamber is pressurized and opened. Remote-control robots enter the chamber first and are used to assess the radiation levels. Once the level and location of the radiation "hot spots" are determined, workers enter the chamber to check for worn or damaged components and to replace them. The process to seal, clean and empty the chamber of all particles, including water vapour and air, requires tremendous heat and vacuum pressure. Any foreign particles left in the chamber can disrupt the free motion of the hydrogen ions and reduce the quality of the ion beam. The worker shown in this picture is kneeling on one of the lower "dees" - so called because they are shaped like the letter "D".
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62. Dees The dees (a model shown) are the "electrodes" used to accelerate the hydrogen ions. The individual elements are the radiofrequency resonators. If you look closely you will see a small gap between the dees (centre horizontal line). By alternating the voltage in the dees from positive to negative and back to positive in a cyclic pattern (23 million times per second!), a positive polarity dee is always presented to approaching negatively charged hydrogen ions as they cross the gap. The other dee, having the opposite polarity, doubles the voltage difference across the gap. The maximum voltage difference is 186,000 volts. Hence the hydrogen ions are boosted in energy on each half turn in the cyclotron. Only those ions crossing the gap during the polarity change will be accelerated. Thus, the hydrogen ions are injected into the centre of the cyclotron in bunches, move through an increasing orbit, and leave in bunches. This method of accelerating particles permits TRIUMF to constantly inject ion "packets" into the cyclotron thus providing a constant high intensity output. While other particle accelerators may produce faster beams, few can produce as an intense a beam as TRIUMF.
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63. Beam Line Extraction Magnets After the electrons are stripped from the hydrogen ions, the remaining protons follow a predetermined curved path out of the cyclotron and into one of the three main beam lines. This picture shows beam line 1 at its emergence from the cyclotron. From here this proton beam is guided by a group of huge electromagnets into meson hall. Magnets are used to bend a beam's path. Also, because the protons in the beam are all positively charged and repel each other, the proton beam spreads and therefore must be "focused" from time to time using a set of magnets. (Next stop: outside south side.)
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64. Synchrocyclotron  =qB/2m
Isochronous : the particle which satisfies the rational frequency in high speeds:
 =qB/2m
Particles with high speeds increase in mass , R=(1/cqB)√Ek^2+2mc^2Ek
so the time of receiving will be later and this is opposite of the linac ,here phase stability should be satisfies as accelerating field come to particles.
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65. Synchro-Cyclotron(1933)
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69. Synchrotron
As momentum and energy increase and the velocity of a particle approaches that of light, then the velocity begins to increase less rapidly than the particle mass, so the revolution frequency drops so that particles are no longer synchronous with the accelerating potential.
The discovery of the synchrotron principle opened the way to the series of circular accelerators, which are used up, to the present day.
A short pulse of particles is injected at low magnetic field, the field rises in proportion to the momentum of particles as they are accelerated and this ensures that the radius of the orbit remains constant.
The accelerated particles take less and less time to complete their orbit so the frequency of the accelerating alternative current must increase as well.
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70. Synchrotron radiation
W=(e2/3e0)(g4b3/R) loss per turn
Ec=(hc/2p)(3g3/2R) peak energy
g=E/mc2
LEP: 100 GeV/beam: R=4.9km W~3 GeV Ec~ 90 keV(hard X-ray) 288 SC RF cavities
Tevatron: E=1 TeV R=1.1km W~ 10 eV Ec~0.4 eV
LHC: E=7 TeV R=4.9 kmW~5 keV, Ec~27 eV
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71. Synchrotron basic scheme
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73. Charged particles receive the energy needed to reach a speed close to that of light from accelerating cavities, which store up electric energy, transferring a small amount to the particles each time they pass. They act like a short section of linear accelerator. Several radio-frequency (rf) cavities are positioned around the ring. These contain the alternating electric field synchronized with the beam’s orbital period, and accelerate the charges.
Dipole magnets keep the particles moving in a circle. Whenever a charged particle is swung in a circle it radiates energy. The greater its centripetal acceleration the greater the rate of radiation, so high-energy electrons in circular accelerators lose a lot of energy as synchrotron radiation.
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74. The opening angle depends on 1/, where  is the gamma factor =1/ √1-v^2/c^2, so the higher energetic are particles, the smaller will be this angle. The radiated power depends on  ^4 and curvature of the path. This must be pumped into the beam through the rf cavities. The LEP radius of about 3,1km is designed to ensure a smooth bending of particle beam to avoid energetic losses.
The radiation losses in electron-positron accelerators are much bigger than in proton-antiproton accelerators. The mass of electron is roughly 2000 times smaller than that of the proton, and therefore, for the same energy it has a , that is 2000 times larger. The radiated power depends on  ^4 , so there are necessary powerful rf systems and much of the voltage per turn, U, to keep the beam from decelerating.
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75. E(GeV) R ( km) N(10^12) U(MeV) P (MW) LEP1 (1989) 45 3.1 260 2.1
Comparison between the colliders’ parameters. The particle energies, collider’s radius, number of particles per bunch, the necessary voltage per turn and radiated power are given in the column for each type of collider
E(GeV)
R ( km)
N(10^12)
U(MeV)
P (MW)
LEP1 (1989) 45
3.1
260
2.1
LEP2 (1995)
100
2800 23
LHC
7000
0.007
0.005
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76. So, each time more energy is pumped into the particles, the magnetic field has to be increased to prevent them for skidding of the ring.
Focusing quadrupole magnets are used to keep the particles tightly packed within the beam. They work in much the same way as lenses do with light. Effective focusing is very important as it enhances the beam intensity and reduces the beam cross-section.
The particle beam travels inside a pipe, from which the air has been removed in order that particles collisions with molecules of air to be avoided. Beam stability depends on the vacuum chamber geometry.
Large particle colliders are used to accelerate particles to very high energies. If the incoming particles are simply slammed into a stationary target, much of the projectile energy is taken up by the target’s recoil and not exploitable. Much more energy is available for the production of new particles if two beams traveling in opposite directions are collided together.
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77. Strong focusing animation
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78. Basic scheme of LEP collider :
The energy of interest to produce new particles in different collisions is Ecm, the enrgy in the center-of-mass frame. In the case of colliders, Ecm=2Ep, where Eb means the energy of one incident particle.
The electron-positron accelerator LEP is a collider. Electrons and positron circulated in opposite directions in the same guide field, being equal in mass but opposite charge, appeared to the magnetic bending and focusing fields as identical currents, one bent to the left, the other to the right. Another CERN collider, the Super Proton Synchrotron (SPS) uses the same technique to circulate protons in one direction and anti-proton in the opposite direction.
  Basic scheme of LEP collider :
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79. Bunches of particles are focused down to the thickness of a hair and made to collide. Each bunch contains more than 10^11 (see Table 1), but on average only one in about collisions between the bunches produces the desired effect-a head-on electron-positron collision. To increase the probability of these events, bunches are made to circulate several hours into the ring.
The LEP2 collider at CERN was until 1999 the largest particle collider in the world, accelerating bunches of electrons and positrons to the energies needed to produce pairs of charged carriers of the weak force W+ and W- particles. Detection of Z0s and Ws, allowed the LEP experiments to make precise tests of the Standard Model of particles and their interactions.
The Large Hadron Collider LHC is designed to accelerate hadrons in experiments probing beyond the Standard Model, more precisely, addressing the following topics: the origin of the particle masses, unification of strong, weak, electromagnetic gauge interaction, and the quarks flavour. LHC machine will share the 27-kilometre LEP tunnel, and will use the most advanced superconducting magnets and accelerators technologies. The magnitude of the magnetic field will be B=8,4T, at a current of A and temperature of T=1,9K.
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81. Process of Synchrotron (IPNS)
First, we actually start with a proton by striping off electrons by using an electrical generator called a Cockcroft-Walton generator. 
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82. Next, we send the proton down a LINAC (linear accelerator) to speed up the proton.  It has to have enough energy to knock the neutron out of our target (explained later).
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83. We then send the proton into a Rapid Cycling Synchrotron to speed it up even further (about 3/4 the speed of light).
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84. The proton is then sent down to the target to knock the neutrons out
The proton is then sent down to the target to knock the neutrons out.   In our case, we use Uranium which has quite a few neutrons in the nucleus.   The proton strikes the nucleus and "knocks" off neutrons.  These neutrons are "slowed" down by moderators and sent down flight paths to all thirteen of the instruments.
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86. LHC
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87. Colliders Circular Linear e- e+ below 10 GeV (BEPS/PEP-2/KEKB)
1 TeV p/1 TeV pbar (Tevatron-FNAL),
27.5 GeV e-/920 GeV p (HERA-DESY)
105 GeV e-/105 GeV e+ (LEP-CERN)
7 TeV p/7TeV p (LHC-CERN)
Linear
50 GeV e-/50 GeV e+ (SLC-SLAC)
~1 TeV e-/~1 TeV e+ (NLC-?)
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