598
K. Hübner et al.
For the antiproton production, the full complement of accelerators and storage
rings in the injector chain is used. The first accelerator in the injector chain is a
400 MeV H − linear accelerator (linac) operating at 200 MHz. Its initial energy was
200 MeV but half of the original drift-tube linac was replaced in 1992–1993 by sidecoupled accelerating structures providing 300 MeV. The protons are transferred to
the booster synchrotron operating with 15 Hz repetition rate and are accelerated to
a kinetic energy of 8 GeV. The intensity is up to 5 × 10 12 protons per booster pulse.
Next the particles are accelerated to 120 GeV in the Main Injector (MI), and hit a
solid metal target followed by a lithium lens.
From the emerging secondary particles anti-protons of 8 GeV kinetic energy are
selected and their phase space density is stepwise increased in two rings in series,
the Debuncher Ring and the Anti-Accumulator Ring; the latter also accumulates the
particles. The anti-protons pass then to the latest addition, the Recycler Ring (RR),
were they are cooled further and a second step of accumulation takes place. The RR
could be fitted into the MI tunnel as its bending and focusing magnets have a small
cross-section the magnetic fields being generated by permanent magnets (1.45 T
field strength). This new storage ring has therefore the same circumference as MI;
it is in operation since 2004. Due to this elaborate anti-proton source the antiproton
production rate has reached nearly 3 × 10 11 anti-protons/h. Still the production rate
of the antiprotons is rather low compared to proton production. Hence, the injector
chain produces and accumulates anti-protons all the time except during the period
of filling the Tevatron with protons and antiprotons which takes about 1 h.
When the Tevatron needs a new fill, which happens about every 10–20 h, the
linac, the booster and MI produce the 36 proton bunches for the Tevatron, then
anti-protons collected in RR are transferred to MI for acceleration to 150 GeV and
injection into the Tevatron. The 36 bunches are arranged in 3 trains of 12 bunches.
Protons and antiprotons circulate on helical orbits produced by high-voltage electrostatic separators to prevent collisions during injection and acceleration. At top
energy, after increasing the focusing in the two collision points equipped with
detectors, the separator configuration is modified to bring the beams in collision
in these two points [67].
A peak luminosity of 4 × 10 32 cm −2 s −1 has been reached by continuously upgrading all the systems, introducing advanced accelerator technology and
stream-lining the operational procedures. The Tevatron has delivered an integrated
luminosity of more than 12 fb −1 to each of the experiments (CDF and D0) before
it ceased operation at the end of September 2011. It was one of the most complex
research instruments ever built and will be known for its advances in accelerator
physics and technological breakthroughs [68].
10.1.7.1 Acknowledgement
Vladimir Shiltsev (FNAL) has contributed with useful suggestions and pertinent
comments to this chapter. Sincere thanks are due to him.
K. Hübner et al.
For the antiproton production, the full complement of accelerators and storage
rings in the injector chain is used. The first accelerator in the injector chain is a
400 MeV H − linear accelerator (linac) operating at 200 MHz. Its initial energy was
200 MeV but half of the original drift-tube linac was replaced in 1992–1993 by sidecoupled accelerating structures providing 300 MeV. The protons are transferred to
the booster synchrotron operating with 15 Hz repetition rate and are accelerated to
a kinetic energy of 8 GeV. The intensity is up to 5 × 10 12 protons per booster pulse.
Next the particles are accelerated to 120 GeV in the Main Injector (MI), and hit a
solid metal target followed by a lithium lens.
From the emerging secondary particles anti-protons of 8 GeV kinetic energy are
selected and their phase space density is stepwise increased in two rings in series,
the Debuncher Ring and the Anti-Accumulator Ring; the latter also accumulates the
particles. The anti-protons pass then to the latest addition, the Recycler Ring (RR),
were they are cooled further and a second step of accumulation takes place. The RR
could be fitted into the MI tunnel as its bending and focusing magnets have a small
cross-section the magnetic fields being generated by permanent magnets (1.45 T
field strength). This new storage ring has therefore the same circumference as MI;
it is in operation since 2004. Due to this elaborate anti-proton source the antiproton
production rate has reached nearly 3 × 10 11 anti-protons/h. Still the production rate
of the antiprotons is rather low compared to proton production. Hence, the injector
chain produces and accumulates anti-protons all the time except during the period
of filling the Tevatron with protons and antiprotons which takes about 1 h.
When the Tevatron needs a new fill, which happens about every 10–20 h, the
linac, the booster and MI produce the 36 proton bunches for the Tevatron, then
anti-protons collected in RR are transferred to MI for acceleration to 150 GeV and
injection into the Tevatron. The 36 bunches are arranged in 3 trains of 12 bunches.
Protons and antiprotons circulate on helical orbits produced by high-voltage electrostatic separators to prevent collisions during injection and acceleration. At top
energy, after increasing the focusing in the two collision points equipped with
detectors, the separator configuration is modified to bring the beams in collision
in these two points [67].
A peak luminosity of 4 × 10 32 cm −2 s −1 has been reached by continuously upgrading all the systems, introducing advanced accelerator technology and
stream-lining the operational procedures. The Tevatron has delivered an integrated
luminosity of more than 12 fb −1 to each of the experiments (CDF and D0) before
it ceased operation at the end of September 2011. It was one of the most complex
research instruments ever built and will be known for its advances in accelerator
physics and technological breakthroughs [68].
10.1.7.1 Acknowledgement
Vladimir Shiltsev (FNAL) has contributed with useful suggestions and pertinent
comments to this chapter. Sincere thanks are due to him.