Electron-driven photon sources have a remarkable track record in science, technology and biomedicine. The underlying physics as well as a demand for seeing matter at the angstrom- and nanoscale ensure that they will continue to be essential for scientific and technical progress in the future. Therefore, many third-generation electron storage rings are either considering or actively undergoing an upgrade to DLSRs. It is imperative that the SLS does likewise. Novel machine elements pioneered at the PSI, in particular reverse-bend dipoles and longitudinal-gradient bends, enable an approximately factor of forty improvement in horizontal electron emittance, despite the small ring circumference. This will maintain the pre-eminence of PSI, the ETH Domain, and Switzerland in photon science, which has been established by the current SLS and SwissFEL for the foreseeable future.
The beamline upgrades will be in two phases. The first phase, in parallel with the machine upgrade, will encompass those beamlines most positively impacted by the increased brightness, probably including ptychography, full-field tomography and macromolecular crystallography. We anticipate that the design, construction and exploitation of SLS 2.0 will enable not only advanced research and education, but also the continued excellence of technology transfer demonstrated by SLS, especially in partnership with Innovaare, the node of the Swiss Innovation Park to be located next to SLS 2.0.

The brightness curves of the typical undulators expected to be installed at SLS 2.0. Although the details might change, it is unlikely that the curves will differ from those shown here by any substantial amount.

The coherent fraction of different sources at SLS 2.0 between photon energies of 15 eV and 40 keV. The lower curves are for the horizontal direction in the electron orbital plane; the upper curves are for the vertical direction. 

The flux in ph/s/0.1% BW as a function of photon energy of selected sources to be installed at SLS 2.0.