10 The Largest Accelerators and Colliders of Their Time
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with carbon beam have been accomplished successfully. Carbon beam intensity is
3–5 × 10 9 ions per pulse (8.2 s), in a single bunch. At the DC flat-bottom, U-70 now
also operates in a beam storage- and stretcher-ring mode for 455 MeV/n carbon ions
enabling their square-wave slow stochastic extraction (0.5–1 s long) via a PiccioniWright technique for an applied fixed-target research [39, 40].
10.1.4 The CERN Intersecting Storage Rings (ISR)
The first ideas for a realistic proton-proton collider were publicly discussed in
1956 [41, 42]. The Accelerator Research Group set up by the CERN Council in
1956 formulated in 1960 the first proposal for a proton-proton collider attached to
the CERN PS. In 1960 construction began on a small-proof-of-principle 1.9 MeV
electron storage ring, the CERN Electron Storage and Accumulation Ring (CESAR)
which experimentally proved the accumulation of particles by RF stacking in 1964,
an essential technique [43] to build up intense beams, a prerequisite for getting the
required luminosity. CESAR also was an important test bed for the for Ultra-High
Vacuum (UHV) technology which had to developed to achieve a very low vacuum
pressure, indispensable for a long lifetime of stored beams. The Design report [44]
was issued in 1964, the project was approved in 1965, and construction lead by
K. Johnsen started without delay. The first proton-proton collisions took place in
1971 with a beam momentum up to 26.5 GeV/c, the maximum momentum available
from the CPS. The ISR consisted of two independent storage rings intersecting
at eight points at an angle of 14.8 ◦ . To create space for long straight sections in
the interaction regions, the circumference of the ring was 1.5 times of that of the
CPS which supplied particles to the ISR through two long transfer lines. The ISR
operated for physics as collider from 1971 to 1983. It was decommissioned after
1984 (Table 10.5).
The CPS was the injector for the ISR supplying mainly protons up to 26.5 GeV/c.
Typical intensities were 3 × 10 12 protons per pulse in 20 bunches every 2.4 s during
the filling process. The filling of one ISR ring took less than 10 min. Later, also
deuterons, alpha particles and antiprotons were accelerated for the ISR.
The ISR team had to tackle a number of technological challenges but the most
important was to assure UHV imperative for a long beam lifetime. The stainless steel
vacuum chamber was in situ bakeable eventually to 300 ◦ C. Pumping was provided
by sputter ion-pumps and, at critical places, Ti-sublimation pumps. All vacuum
chambers had to be glow-discharge cleaned. The continuous effort eventually
resulted in average pressure below 10 −11 Torr (N 2 equivalent) reducing beam loss
rates to typically around one part per million per minute during physics runs. Beams
of physics quality could last 40–50 h. Beam currents of 10 A were achieved already
after start-up. Later up to 57 A were stored per ring with 30–40 A as typical value.
The proton-proton initial luminosity (design 4 × 10 30 cm −2 s −1 ) was increased
from 1.6 × 10 30 cm −2 s −1 in 1971 to 1.4 × 10 32 cm −2 s −1 in the superconducting
low-beta section installed in one of the interaction points in 1982, which stayed the
591
with carbon beam have been accomplished successfully. Carbon beam intensity is
3–5 × 10 9 ions per pulse (8.2 s), in a single bunch. At the DC flat-bottom, U-70 now
also operates in a beam storage- and stretcher-ring mode for 455 MeV/n carbon ions
enabling their square-wave slow stochastic extraction (0.5–1 s long) via a PiccioniWright technique for an applied fixed-target research [39, 40].
10.1.4 The CERN Intersecting Storage Rings (ISR)
The first ideas for a realistic proton-proton collider were publicly discussed in
1956 [41, 42]. The Accelerator Research Group set up by the CERN Council in
1956 formulated in 1960 the first proposal for a proton-proton collider attached to
the CERN PS. In 1960 construction began on a small-proof-of-principle 1.9 MeV
electron storage ring, the CERN Electron Storage and Accumulation Ring (CESAR)
which experimentally proved the accumulation of particles by RF stacking in 1964,
an essential technique [43] to build up intense beams, a prerequisite for getting the
required luminosity. CESAR also was an important test bed for the for Ultra-High
Vacuum (UHV) technology which had to developed to achieve a very low vacuum
pressure, indispensable for a long lifetime of stored beams. The Design report [44]
was issued in 1964, the project was approved in 1965, and construction lead by
K. Johnsen started without delay. The first proton-proton collisions took place in
1971 with a beam momentum up to 26.5 GeV/c, the maximum momentum available
from the CPS. The ISR consisted of two independent storage rings intersecting
at eight points at an angle of 14.8 ◦ . To create space for long straight sections in
the interaction regions, the circumference of the ring was 1.5 times of that of the
CPS which supplied particles to the ISR through two long transfer lines. The ISR
operated for physics as collider from 1971 to 1983. It was decommissioned after
1984 (Table 10.5).
The CPS was the injector for the ISR supplying mainly protons up to 26.5 GeV/c.
Typical intensities were 3 × 10 12 protons per pulse in 20 bunches every 2.4 s during
the filling process. The filling of one ISR ring took less than 10 min. Later, also
deuterons, alpha particles and antiprotons were accelerated for the ISR.
The ISR team had to tackle a number of technological challenges but the most
important was to assure UHV imperative for a long beam lifetime. The stainless steel
vacuum chamber was in situ bakeable eventually to 300 ◦ C. Pumping was provided
by sputter ion-pumps and, at critical places, Ti-sublimation pumps. All vacuum
chambers had to be glow-discharge cleaned. The continuous effort eventually
resulted in average pressure below 10 −11 Torr (N 2 equivalent) reducing beam loss
rates to typically around one part per million per minute during physics runs. Beams
of physics quality could last 40–50 h. Beam currents of 10 A were achieved already
after start-up. Later up to 57 A were stored per ring with 30–40 A as typical value.
The proton-proton initial luminosity (design 4 × 10 30 cm −2 s −1 ) was increased
from 1.6 × 10 30 cm −2 s −1 in 1971 to 1.4 × 10 32 cm −2 s −1 in the superconducting
low-beta section installed in one of the interaction points in 1982, which stayed the