10 The Largest Accelerators and Colliders of Their Time
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the beam energy. SPEAR was very productive in particle physics with the discovery
of the J/Psi and tau. SPEAR has been upgraded to a medium emittance light source.
10.3.3.9 VEPP-2M
VEPP-2M at BINP reached a luminosity 100 times VEPP-2. VEPP-2 served for a
while as the injector [93, 98]. The ring operated with a superconducting wiggler with
an 8 T field that was used to increase the radial emittance, decrease the damping
time, increase the beam-beam tune shift for a higher luminosity, and also for
suppression of intra-beam scattering. The collider could generate and use polarized
beams. The particle physics results are many. Round beams have been studied at
VEPP-2M to try to reduce beam-beam effects and, thus, increase the allowed beambeam tune shift. Round beams required the use of solenoidal focusing at the IPs.
10.3.3.10 DORIS
DORIS at DESY started as a two ring collider with beams brought into collision
with vertical dipoles in the IR and had a vertical crossing angle [99]. Injection was
from a linac and a booster synchrotron. The single bunch currents in the collider
were limited by higher parasitic modes in the RF cavities. The luminosity was
limited by effects of the vertical crossing angle. DORIS was subsequently converted
to a single ring collider with head-on collisions and went on to do many years of B
meson physics.
10.3.3.11 DCI
DCI at Orsay was a two ring collider designed for high energy physics studies
of charged and neutral particles and also of two photon physics [100]. The two
rings were mounted one above the other and the beams were brought into collision
with vertical bends near the IR. Both rings could store both e − and e + . The rings
could operate with either two bunch collisions or four bunch collisions (opposite
in both rings). The four bunch collisions aimed at charge cancelation of the beambeam effects allowing higher beam-beam tune shifts and thus higher luminosity.
The four beam scheme in reality partially worked but was strongly limited by
incoherent and coherent beam-beam modes. This topic of four beam collisions has
been theoretically studied for many years since. The DCI collider mostly operated
in a one bunch mode in each ring (out of time) generating twice the luminosity. The
peak luminosity scaled as the energy squared.
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the beam energy. SPEAR was very productive in particle physics with the discovery
of the J/Psi and tau. SPEAR has been upgraded to a medium emittance light source.
10.3.3.9 VEPP-2M
VEPP-2M at BINP reached a luminosity 100 times VEPP-2. VEPP-2 served for a
while as the injector [93, 98]. The ring operated with a superconducting wiggler with
an 8 T field that was used to increase the radial emittance, decrease the damping
time, increase the beam-beam tune shift for a higher luminosity, and also for
suppression of intra-beam scattering. The collider could generate and use polarized
beams. The particle physics results are many. Round beams have been studied at
VEPP-2M to try to reduce beam-beam effects and, thus, increase the allowed beambeam tune shift. Round beams required the use of solenoidal focusing at the IPs.
10.3.3.10 DORIS
DORIS at DESY started as a two ring collider with beams brought into collision
with vertical dipoles in the IR and had a vertical crossing angle [99]. Injection was
from a linac and a booster synchrotron. The single bunch currents in the collider
were limited by higher parasitic modes in the RF cavities. The luminosity was
limited by effects of the vertical crossing angle. DORIS was subsequently converted
to a single ring collider with head-on collisions and went on to do many years of B
meson physics.
10.3.3.11 DCI
DCI at Orsay was a two ring collider designed for high energy physics studies
of charged and neutral particles and also of two photon physics [100]. The two
rings were mounted one above the other and the beams were brought into collision
with vertical bends near the IR. Both rings could store both e − and e + . The rings
could operate with either two bunch collisions or four bunch collisions (opposite
in both rings). The four bunch collisions aimed at charge cancelation of the beambeam effects allowing higher beam-beam tune shifts and thus higher luminosity.
The four beam scheme in reality partially worked but was strongly limited by
incoherent and coherent beam-beam modes. This topic of four beam collisions has
been theoretically studied for many years since. The DCI collider mostly operated
in a one bunch mode in each ring (out of time) generating twice the luminosity. The
peak luminosity scaled as the energy squared.