12
E. Wilson and B. J. Holzer
Fig. 1.8 The CERN 25 GeV proton synchrotron
convex and concave lenses which will transport rays which pass through the centres
of defocusing lenses.
Alternating gradient or strong focusing greatly reduces the beam’s excursions
and so the cross section of the magnet gap by more than an order of magnitude.
Its discovery enabled Brookhaven and CERN to build the next generation of
proton synchrotrons, AGS and PS, to reach 30 GeV—five times the energy of the
Bevatron—yet use beam pipes of only a few centimetres height and width.
This was to lead to huge economies in the cost per unit length of the magnet
system. Figure 1.8 shows how this was applied to the first of the two synchrotrons,
AGS and PS that used this focusing system. From then on all synchrotrons and, later,
storage ring colliders use this scheme. The history of synchrotrons has been always
to seek methods of improving focusing and economizing on magnet aperture. The
only other step function in their development to higher energies has been the use
of superconducting magnets whose higher fields reduce the circumference of the
machine by a factor between 3 and 5.
1.2.7 Phase Stability
When the first synchrotrons were built it was by no means obvious that the
circulating beam and the accelerating voltage would remain in step. There were
those who thought that any slight mistiming of the sine wave of accelerating voltage
in the cavity might build up over many turns until particles would begin to arrive
E. Wilson and B. J. Holzer
Fig. 1.8 The CERN 25 GeV proton synchrotron
convex and concave lenses which will transport rays which pass through the centres
of defocusing lenses.
Alternating gradient or strong focusing greatly reduces the beam’s excursions
and so the cross section of the magnet gap by more than an order of magnitude.
Its discovery enabled Brookhaven and CERN to build the next generation of
proton synchrotrons, AGS and PS, to reach 30 GeV—five times the energy of the
Bevatron—yet use beam pipes of only a few centimetres height and width.
This was to lead to huge economies in the cost per unit length of the magnet
system. Figure 1.8 shows how this was applied to the first of the two synchrotrons,
AGS and PS that used this focusing system. From then on all synchrotrons and, later,
storage ring colliders use this scheme. The history of synchrotrons has been always
to seek methods of improving focusing and economizing on magnet aperture. The
only other step function in their development to higher energies has been the use
of superconducting magnets whose higher fields reduce the circumference of the
machine by a factor between 3 and 5.
1.2.7 Phase Stability
When the first synchrotrons were built it was by no means obvious that the
circulating beam and the accelerating voltage would remain in step. There were
those who thought that any slight mistiming of the sine wave of accelerating voltage
in the cavity might build up over many turns until particles would begin to arrive