618
K. Hübner et al.
at the IP using permanent magnet quadrupoles (0.5 m long) was installed reaching
a vertical beta of 8.5 cm. Higher RF voltage was used to reduce the bunch length to
match. BEPC measured precisely the tau lepton mass to 0.2 MeV out of a mass of
1777 MeV.
10.3.3.19 LEP
LEP at CERN has four collision points and is the largest (27 km) and highest energy
(104.5 GeV per beam) collider built to date [109]. The particle physics completed
at LEP included precise measurements of Z and W bosons, determination of the
number of light neutrinos to be three, and exclusion of the Higgs mass below
114 GeV. To reduce power usage five cell RF cavities with attached spherical copper
storage cavities were used to reach about 80 GeV. To reach 104.5 GeV additional
superconducting RF cavities were added incorporating sputtered Nb on Cu surfaces.
The bending dipoles in LEP needed only a low field so the steel laminations were
spaced by concrete filler material. At the Z resonance the luminosity was limited
by the beam-beam effect. At higher energies the luminosity limit was the available
RF power. A Pretzel orbit scheme (8 and later 12 bunches) was used to increase the
luminosity. At high energy, a low emittance optics was implemented. A beam-beam
tune shift of about 0.083 as reached at 98 GeV.
10.3.3.20 DAFNE
DAFNE at Frascati was built to make precision measurements of K meson physics.
Injection is made with a full energy linac and damping ring [110]. DAFNE operates
with damping wigglers to decrease the emittances and shorten the damping time. A
crab waist scheme was installed in the IP for increased luminosity and for tests of
the SuperB IP concept [111]. Rolled permanent-magnet IP quadrupoles were used
to compensate the detector solenoidal field.
10.3.3.21 PEP-II
PEP-II at SLAC was an asymmetric collider with two rings made to measure the
properties of the b quark sector, the CP violation in the BB system, and to confirm
the CKM matrix [112]. Injection was made at full energy at up to 30 Hz from
the SLAC 3 km linac with the SLC e − and e + damping rings and either e − or
e + accelerated on any given linac pulse. Accelerator advances at PEP-II include
head-on asymmetric collisions at one IR, large bore permanent-magnet IP dipole
and quadrupoles, local beta beats to correct chromaticity in the IP, fast IP position
feedback, and bunch-by-bunch transverse and longitudinal feedbacks. The nearest
final focus quadrupoles were inside the detector leaving a free space to the IP of
about 0.5 m on each side. PEP-II holds the world’s record of stored positrons at
K. Hübner et al.
at the IP using permanent magnet quadrupoles (0.5 m long) was installed reaching
a vertical beta of 8.5 cm. Higher RF voltage was used to reduce the bunch length to
match. BEPC measured precisely the tau lepton mass to 0.2 MeV out of a mass of
1777 MeV.
10.3.3.19 LEP
LEP at CERN has four collision points and is the largest (27 km) and highest energy
(104.5 GeV per beam) collider built to date [109]. The particle physics completed
at LEP included precise measurements of Z and W bosons, determination of the
number of light neutrinos to be three, and exclusion of the Higgs mass below
114 GeV. To reduce power usage five cell RF cavities with attached spherical copper
storage cavities were used to reach about 80 GeV. To reach 104.5 GeV additional
superconducting RF cavities were added incorporating sputtered Nb on Cu surfaces.
The bending dipoles in LEP needed only a low field so the steel laminations were
spaced by concrete filler material. At the Z resonance the luminosity was limited
by the beam-beam effect. At higher energies the luminosity limit was the available
RF power. A Pretzel orbit scheme (8 and later 12 bunches) was used to increase the
luminosity. At high energy, a low emittance optics was implemented. A beam-beam
tune shift of about 0.083 as reached at 98 GeV.
10.3.3.20 DAFNE
DAFNE at Frascati was built to make precision measurements of K meson physics.
Injection is made with a full energy linac and damping ring [110]. DAFNE operates
with damping wigglers to decrease the emittances and shorten the damping time. A
crab waist scheme was installed in the IP for increased luminosity and for tests of
the SuperB IP concept [111]. Rolled permanent-magnet IP quadrupoles were used
to compensate the detector solenoidal field.
10.3.3.21 PEP-II
PEP-II at SLAC was an asymmetric collider with two rings made to measure the
properties of the b quark sector, the CP violation in the BB system, and to confirm
the CKM matrix [112]. Injection was made at full energy at up to 30 Hz from
the SLAC 3 km linac with the SLC e − and e + damping rings and either e − or
e + accelerated on any given linac pulse. Accelerator advances at PEP-II include
head-on asymmetric collisions at one IR, large bore permanent-magnet IP dipole
and quadrupoles, local beta beats to correct chromaticity in the IP, fast IP position
feedback, and bunch-by-bunch transverse and longitudinal feedbacks. The nearest
final focus quadrupoles were inside the detector leaving a free space to the IP of
about 0.5 m on each side. PEP-II holds the world’s record of stored positrons at