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In 2003 the PSI initiated the low emittance gun project (LEG) with the aim of constructing an ultra-bright electron source based on field-emission. This development is particularly interesting for the realization of the next generation of X-ray light sources, because it paves the way for a more economic approach to their construction and operation. At present the fabrication and tests of the electron source are in progress and complemented with a case study for an X-ray free-electron laser light source. This could grant the SLS science community access to the femto-second time domain with atomic resolution.

The design of an electron gun capable of producing beams with an emittance one order of magnitude lower than current technology would reduce considerably the cost and size of a free electron laser radiating at 0.1 nm. An electron source based on field emission is an attractive alternative for a high brightness source: thousands of high current density beams (10^8 A/cm^2) can be produced and individually focused. The development of a gun based on field emission cathodes implies many innovations in regards to current state of the art guns. The field emitter source will be inserted in a high-gradient diode configuration coupled with a radiofrequency (RF) structure. In the diode part a high electric field (several hundreds of MV/m) will limit the degradation of beam emittance due to space-charge effects. This first acceleration will be obtained with high voltage pulses (~500 kV in 500 ns) synchronized with the low voltage pulses applied between the tips and the extracting gate. This diode part will then be followed by an RF accelerating structure in order to bring the electrons to relativistic energies.

The design of an electron gun capable of producing beam emittance one order of magnitude lower than current technology would reduce considerably the cost and size of a free electron laser radiating at 0.1 nm. Field emitter arrays (FEAs) including a gate and a focusing layer are an attractive technology for such high brightness sources. Electrons are extracted from micrometric tips thanks to voltage pulses applied between the gate and the tips. The focusing layer should then reduce the initial divergence of each emitted beamlet. This FEA will be inserted in a high-gradient diode configuration couplesd with a radiofrequency (RF) structure. In the diode part the high electric field (several hundreds of MV/m) will limit the degradation of emittance due to space-charge effects. The first acceleration will be obtained with high voltage pulses (about one megavolt in a few hundreds of nanoseconds) synchronized with the low voltage pulses applied to the FEA (200-300 V in less than one nanosecond at a frequency lower than a kilohertz). This diode part will then be followed by an RF accelerating structure in order to bring the electrons to relativistic energies.

The hydrostatic levelling system (HLS) at the Swiss Light Source (SLS), Switzerland, showed reliable long-term stability over the past years. The high resolution of the HLS allows the observation of ground deformations induced by tidal forces. As a special feature, each level sensor is equipped with a touch point which allows a remote re-calibration of the system. In this presentation, the latest results are discussed and an overview of the HLS design at the SLS is given. In addition, the new PWR (Precision-Wide-Range)-HLS, a more compact OEM - level sensor version, is introduced.