594
K. Hübner et al.
(250 GeV maximum) during a short pause in the acceleration followed by extraction
at top energy to the North Hall. After the upgrading to 450 GeV of the transfer
line to the West Hall in 1983, simultaneous resonant extraction to both areas was
implemented by an appropriate adjustment of the horizontal betatron phase advance
in the ring. The sharing ratio between the two clients was fully adjustable. Extraction
towards the West Hall was terminated in 2003 to free resources for LHC.
In 1986 and 1987 two exploratory fixed-target runs with ions took place after
linac 2 had become operational freeing linac 1 which had in the meantime been
equipped with the appropriate front-end for ion operation. In 1986, fully stripped
oxygen ions were accelerated for the first time to 200 GeV/n after the SPS had been
set up with a deuteron beam of more convenient higher intensity. In the second run,
in 1987, sulphur ions were used. The sulphur runs were resumed from 1990 to 1992
providing 9 × 10 9 charges per pulse with four batches injected from the CPS. After
the construction of the dedicated heavy-ion linac (linac 3) lead ions at 177 GeV/u
were available for the experiments from 1994 to 2002 and indium at 158 GeV/u in
2003. No ion runs took place in 1997 and 2001. The SPS delivered up to 6 × 10 10
fully-stripped ions in terms of charges per pulse [52].
It is worthwhile to mention that the SPS also accelerated electrons and positrons
for injection into LEP in the years 1989 to 2000. This had required substantial
modifications. Since the traveling-wave cavities could accelerate the beam only
to 14 GeV, 32 copper-based standing-wave cavities operating at 200 MHz and
providing a peak-voltage of 30 MV were added. Ejection and injection channels
were equipped appropriately and a campaign of meticulously shielding the magnet
coils against synchrotron radiation was conducted [53]. The LEP injection energy
was first set to 20 GeV and, later, when the standing-wave cavities were replaced
by two four-cell superconducting RF structures, the LEP injection energy could be
raised to 22 GeV.
The SPS acts as injector into the LHC providing protons at 450 GeV since 2008
and ions at 176 GeV/u since 2010 [54]. Lead is the preferred ion species for the first
years of operation. This new role required a number of hardware modifications and,
in particular, the addition of a new extraction system for the anti-clockwise LHC
ring which serves also the target for the new long-base line neutrino beam towards
Gran Sasso in Italy. Two new beam lines towards the LHC had to be built.
10.1.6 The CERN Super Proton Synchrotron (SPS) as
Proton-Antiproton Collider
The proposal to use the SPS as proton-antiproton collider was made in 1976 [55].
The required increase of phase space density of the secondary antiprotons was to be
produced by stochastic cooling invented by S. van der Meer [56] which had been
experimentally demonstrated in the ISR [57]. Simultaneous stochastic cooling in
transverse and longitudinal phase space at cooling rates several orders higher than
K. Hübner et al.
(250 GeV maximum) during a short pause in the acceleration followed by extraction
at top energy to the North Hall. After the upgrading to 450 GeV of the transfer
line to the West Hall in 1983, simultaneous resonant extraction to both areas was
implemented by an appropriate adjustment of the horizontal betatron phase advance
in the ring. The sharing ratio between the two clients was fully adjustable. Extraction
towards the West Hall was terminated in 2003 to free resources for LHC.
In 1986 and 1987 two exploratory fixed-target runs with ions took place after
linac 2 had become operational freeing linac 1 which had in the meantime been
equipped with the appropriate front-end for ion operation. In 1986, fully stripped
oxygen ions were accelerated for the first time to 200 GeV/n after the SPS had been
set up with a deuteron beam of more convenient higher intensity. In the second run,
in 1987, sulphur ions were used. The sulphur runs were resumed from 1990 to 1992
providing 9 × 10 9 charges per pulse with four batches injected from the CPS. After
the construction of the dedicated heavy-ion linac (linac 3) lead ions at 177 GeV/u
were available for the experiments from 1994 to 2002 and indium at 158 GeV/u in
2003. No ion runs took place in 1997 and 2001. The SPS delivered up to 6 × 10 10
fully-stripped ions in terms of charges per pulse [52].
It is worthwhile to mention that the SPS also accelerated electrons and positrons
for injection into LEP in the years 1989 to 2000. This had required substantial
modifications. Since the traveling-wave cavities could accelerate the beam only
to 14 GeV, 32 copper-based standing-wave cavities operating at 200 MHz and
providing a peak-voltage of 30 MV were added. Ejection and injection channels
were equipped appropriately and a campaign of meticulously shielding the magnet
coils against synchrotron radiation was conducted [53]. The LEP injection energy
was first set to 20 GeV and, later, when the standing-wave cavities were replaced
by two four-cell superconducting RF structures, the LEP injection energy could be
raised to 22 GeV.
The SPS acts as injector into the LHC providing protons at 450 GeV since 2008
and ions at 176 GeV/u since 2010 [54]. Lead is the preferred ion species for the first
years of operation. This new role required a number of hardware modifications and,
in particular, the addition of a new extraction system for the anti-clockwise LHC
ring which serves also the target for the new long-base line neutrino beam towards
Gran Sasso in Italy. Two new beam lines towards the LHC had to be built.
10.1.6 The CERN Super Proton Synchrotron (SPS) as
Proton-Antiproton Collider
The proposal to use the SPS as proton-antiproton collider was made in 1976 [55].
The required increase of phase space density of the secondary antiprotons was to be
produced by stochastic cooling invented by S. van der Meer [56] which had been
experimentally demonstrated in the ISR [57]. Simultaneous stochastic cooling in
transverse and longitudinal phase space at cooling rates several orders higher than