MODEL PARAMETERS

The SLS lattice in ``D2A optics'' as current reference lattice has dispersion free straight sections with mini-$\beta$-optics, and a natural emittance of 4.8 nm at 2.4 GeV. The working point was set to 20.82/8.28 as a compromise between sextupole Hamiltonian suppression requirements  [1] and vertical closed orbit distortion minimization. This is not the lattice mode with optimum dynamic aperture but still provides a TRELMA² of 5.1% (fixed-$\delta$-calculation), which is larger than 3.9% provided by the 2.6 MV RF system [7].

At SLS magnets are rigidly mounted onto girders, the girders are connected into a ``train link'' by means of horizontal sensor and hydrostatic levelling systems [3]. The following table gives alignment (horizontal & vertical) and tilt errors considered as realistic (rms values, cut at $2\sigma$):

	shift $[\mu m]$	tilt $[\mu rad]$
elements to girder	50	100
girder to girder	100	0
girder absolute	300	25

After setting the misalignments a SVD closed orbit correction was applied, preceded by a beam threader, if no initial orbit was found, and followed by an emittance coupling suppression by means of small skew quadrupoles [4]. The average coupling was 0.27% before and 0.10% after coupling suppression.

The narrow gap from insertion devices was included in tracking by reducing the vertical aperture on a length of 2 m in all six short straight sections ( $\beta_y^*=$ 1.6 m).

Tracking was done for 1.5 synchrotron oscillation periods (100...300 turns). Binary search resolution for determination of local MA was 0.01%. All calculations assumed 1 nCb single bunch charge.

  

Figure 2: Touschek lifetime as a function of RF voltage for progressive model refinements: