CONCLUSION

Mini gap insertion devices in the lattice partially reverse the usual dependency of Touschek lifetime on emittance coupling: suppression of the coupling factor to values as low as 10^-3 gives optimum beam lifetime and removes sensitivity of the lifetime to particular alignment error settings while on the other hand providing high brightness. Larger emittance coupling does not increase the beam life time.

Increasing the RF voltage showed insignificant gain in lifetime, at least for the lattice mode studied here.

For SLS at standard operation conditions we expect a total lifetime of $3\frac{1}{2}$ hrs which may be increased to 8 hrs by means of a 3^rd harmonic cavity.