International Scoping Study
Machine Working Group
Acceleration
Linac

This is a lattice description of the linac, as designed by Alex Bogacz. It accelerates from a momentum of 273.103 MeV/c. The RF phase is zero on crest. The cavities are assumed to be open-ended pillbox cavities.

All numbers are obtained from the DIMAD-style input file. The gradients are computed from the energy gains there, corrected for speed-of-light transit time factors. The solenoid fields are computed using momentum which are found by integrating through the cavities in 1 cm steps using the given phase, where the zero-crossing of the phase corresponds to zero energy gain through the cavity.

To get the correctly matched lattice, one must include the edge focusing in the cavities. One must also include edge focusing in the solenoids by adding additional cylindrically-symmetric focusing on the ends. The kick on each end is B²ar/[8(pc/q)²], where B is the solenoid field, a is the aperture radius of the solenoid, r is the particle radius, p is the particle momentum, c is the speed of light, and q is the particle charge. Note this is a defocusing kick, which arises from the fact that the solenoid length times the integral of B² is less than the integral of B, squared.

This lattice breaks up into three types of cells: 12 short cells (3 m long), 18 medium cells (5 m long), and 22 long cells (8 m long). The short cells have a = 19.5 cm for their solenoids and one single-cell cavity. The medium cells have a = 19.5 cm for their solenoids and one two-cell cavity. The long cells have a = 15 cm for their solenoids and two two-cell cavities. All the cavity apertures are 46 cm diameter, and the nominal gradient is 15 MV/m (despite the pillbox numbers below).

This description should exactly match the ICOOL input file.

This table gives the lattice: