Minimum effective emittance in synchrotron radiation sources composed of modified Chasman Green lattice

As a guideline on designing low emittance synchrotron radiation sources composed of the modified Chasman Green lattice where the doubly achromatic condition is broken, the minimum effective emittance is derived taking into account of momentum spread and insertion devices. The effective emittance represents the total spread of circulating beams at a source point in a median plane. Dependence of the minimum effective emittance on parameters of insertion devices and storage rings is numerically investigated by derived formulae. On the basis of calculation results, a simple criterion on breaking the achromatic condition to reduce the effective emittance is also shown.