Lattice Definitions

The APS booster lattice consists of 2 superperiods, 2 quadrants per superperiod with 10 FODO cells per quadrant. The magnets are arranged in five main families wired in series and powered by a single supply. There are 68 dipoles (BM), 40 focussing (QF) and 40 defocussing quadrupoles (QD) and 32 focussing (SF) and 32 defocussing (SD) sextupoles. Orbit correction is performed using 40 horizontal and 40 vertical correctors and 80 horizontal and vertical BPMs. Injection is on-axis using a single septum and kicker approximately 90 degrees in betatron phase advance apart. Extraction uses a single kicker and septum. The injection septum is located in the missing magnet region of the second superiod and the extraction septum is located in the straight section just after the first superperiod. Injection and extraction are performed ``on the fly'' which means that the magnetic fields increase linearly (no flat-tops or porches) during the single turn injection and extraction process. Four LEP style normal conducting cavities located in the straight sections are used to supply rf power in the booster.

The lattice design is the so called ``missing magnet'' lattice where one dipole at each end of the superperiod is omitted to match the dispersion in the straight sections to zero. This is only true for the original lattice design which has 132 nm emittance. Two other lattices were developed with lower emittance. Presently, the APS operates using the 92 nm emittance lattice for normal operations. The 92 nm lattice emittance is actually 65 nm due (measured to be 77 nm) (OAG-TN-2006-025),  [2], due to the fact that the booster is run ``off-momentum''. Off-momentum operation is guaranteed by the increased rf frequency due to the shorter ``decker distorted'' storage ring. Running off-momentum has the effect of adding additional dipole bending in the quadrupoles and thereby increasing the horizontal damping partition number at the expense of the longitudinal damping partition number. (OAG-TN-2003-005),  [3]. The other two lattices have similarly reduced emittance compared to their on-momentum emittance. The major difference between the three lattices are the quadrupole strengths which set the tune and sextupole strengths which correct the natural chromaticities.

The links listed below give the full lattice definitions in MAD format for each booster lattice. The first three figures below show one superperiod of the booster for each lattice defined by its 7 GeV emittance. The fourth figure shows the magnet family current each 2 Hz cycle. Finally the fifth figure shows the booster as-built layout.

• Full lattice description for the 92 nm operational lattice (elegant input file)
• Full lattice description for the 109 nm backup lattice (elegant input file)
• Full lattice description for the ``original design'' 132 nm backup lattice (elegant input file)

Figure 1: Twiss parameters for the 92 nm emittance lattice.

Figure 2: Twiss parameters for the 109 nm emittance lattice.

Figure 3: Twiss parameters for the 132 nm ``original design'' emittance lattice.

Figure 4: Booster magnet family currents each 2 Hz cycle for the 92 nm emittance lattice. Injection at 325 MeV is at approximately 17.5 ms and extraction at 7 GeV is at approximately 243.3 ms.

Figure 5: Booster layout showing the injection and extraction pulsed magnets and placement of the four 5-cell LEP style normal conducting cavities.