Beam extraction - 50th anniversary of the CERN Proton Synchrotron

Section 54
Section 55
Section 21
Section 20
Extraction line
Flying wires
Sextupole magnets
Kicker magnet
Octupole magnets
Slow bump
Extraction
septum
Section 16
Section 64
Section 71
Fig. 26: Schematic layout of the PS machine with the elements used for the experimental study of the
novel multi-turn extraction (left). Schematic layout of the mechanism of the PS wire scanner (upper
right). The installation of the scintillators on both sides of the vacuum pipe is also shown (lower
right).
Under these new conditions it was indeed possible to increase the fraction of particles inside the
islands, achieving a value of 18% against a previous value of about 13%. It is worth while mentioning
that for the optimal performance of the SPS machine, the tolerance for the fraction of particles in each
beamlet is (20±5)%. Therefore, if this needs to hold for the central core, then, the four beamlets should
satisfy the tighter limit (20±1)% as any deviation in beamlets intensity is reflected on the core amplified
by a factor of four. However, the price to pay was the presence of slightly higher losses during resonance
crossing up to the level of 2%–3% of the total beam intensity.
The main parameters of the single-bunch beams used in the experimental campaign are
summarized in Table 1.
Table 1: Parameters of the single-bunch beams used for the experimental tests of the novel multi-turn
extraction. The emittance is the normalized, one-sigma value.
Parameter
Intensity
(protons/bunch)
ε* H (σ)
(μm)
ε* V (σ)
(μm)
Δp/p (σ)
10 −3
Low-intensity, pencil beam 5×10 11 2.3 1.3 0.25
Low-intensity, large horizontal emittance 5×10 11 6.2 1.6 0.25
High-intensity beam 6×10 12 9.4 6.4 0.60
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