10 The Largest Accelerators and Colliders of Their Time
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than a factor of 40, and polarized proton operation at 510 GeV center-of-mass
energy with peak luminosity of 250 × 10 30 cm −2 s −1 with store-averaged beam
polarization of up to 60%. Major upgrades to RHIC included electron lenses to
compensate for head-on beam-beam interactions [82] and a superconducting storage
RF system. In preparation for operation at very low center-of-mass energies with
beam energies below the RHIC injection energy bunched beam electron cooling of
both RHIC ion beams is being installed [83].
10.3 Electron Accelerators and Electron–Positron Colliders
J. Seeman
10.3.1 Cyclotrons
Cyclotrons are one of the first accelerators invented and use a fixed magnetic field
and a radiofrequency (RF) cavity to accelerate electrons in ever increasing orbits
[84]. The electron beam is injected into the center of a circular magnetic field region
between magnet poles and then made to circulate. These electrons are accelerated
twice on each turn and are extracted at high energy near the outer edge of the
accelerator. The cyclotron can produce continuous beams leading to high power
applications. The first cyclotron was built at Berkeley in 1931 with a diameter
of 11 cm. Many more cyclotrons were to follow over the years. The TRIUMF
cyclotron in use now is located in Vancouver, Canada, and has a diameter of 18 m
and has a 4000 ton magnet. The beam energy is limited by the field strength and the
diameter of the magnetic pole. Cyclotrons are mainly used to produce high beam
power for science, for materials analysis, and industrial processing applications.
Two cyclotrons are shown in Fig. 10.10.
10.3.2 Synchrotrons
A synchrotron is a fixed circumference accelerator that increases the electron beam
energy using RF accelerating cavities but keeps the radius constant by increasing the
magnetic fields. The field used to bend the beam in a circle is ramped in proportion
to the beam energy [85]. The beam is injected at low energy and magnetic fields,
accelerated, and then extracted at high energy and magnetic fields. The highest
beam energy is limited by the strength of the magnetic field and the diameter of the
accelerator which can be over 1 km and is usually limited by the site or its building.
Synchrotrons are pulsed machines due to the cyclic ramping of the magnetic fields.
The RF system accelerates the beam during the ramp and keeps the beam bunched.
609
than a factor of 40, and polarized proton operation at 510 GeV center-of-mass
energy with peak luminosity of 250 × 10 30 cm −2 s −1 with store-averaged beam
polarization of up to 60%. Major upgrades to RHIC included electron lenses to
compensate for head-on beam-beam interactions [82] and a superconducting storage
RF system. In preparation for operation at very low center-of-mass energies with
beam energies below the RHIC injection energy bunched beam electron cooling of
both RHIC ion beams is being installed [83].
10.3 Electron Accelerators and Electron–Positron Colliders
J. Seeman
10.3.1 Cyclotrons
Cyclotrons are one of the first accelerators invented and use a fixed magnetic field
and a radiofrequency (RF) cavity to accelerate electrons in ever increasing orbits
[84]. The electron beam is injected into the center of a circular magnetic field region
between magnet poles and then made to circulate. These electrons are accelerated
twice on each turn and are extracted at high energy near the outer edge of the
accelerator. The cyclotron can produce continuous beams leading to high power
applications. The first cyclotron was built at Berkeley in 1931 with a diameter
of 11 cm. Many more cyclotrons were to follow over the years. The TRIUMF
cyclotron in use now is located in Vancouver, Canada, and has a diameter of 18 m
and has a 4000 ton magnet. The beam energy is limited by the field strength and the
diameter of the magnetic pole. Cyclotrons are mainly used to produce high beam
power for science, for materials analysis, and industrial processing applications.
Two cyclotrons are shown in Fig. 10.10.
10.3.2 Synchrotrons
A synchrotron is a fixed circumference accelerator that increases the electron beam
energy using RF accelerating cavities but keeps the radius constant by increasing the
magnetic fields. The field used to bend the beam in a circle is ramped in proportion
to the beam energy [85]. The beam is injected at low energy and magnetic fields,
accelerated, and then extracted at high energy and magnetic fields. The highest
beam energy is limited by the strength of the magnetic field and the diameter of the
accelerator which can be over 1 km and is usually limited by the site or its building.
Synchrotrons are pulsed machines due to the cyclic ramping of the magnetic fields.
The RF system accelerates the beam during the ramp and keeps the beam bunched.