The Surface/Interface: Microscopy beamline of the Swiss Light Source started operation in 2001. In 2007 the beamline has been significantly upgraded with a second refocusing section and a blazed grating optimized for high photon flux. Two Apple II type undulators with a plane grating monochromator using the collimated light scheme deliver photons with an energy from 90 eV to about 2 keV with variable polarization for the photoemission electron microscope (PEEM) as the primary user station. We measured a focus of (45 × 60) µm (v × h) and a photon flux > 10 12 photon/s for all gratings. Polarization switching within a few seconds is realized with the small bandpass of the monochromator and a slight detuning of the undulator.
The backward region of the H1 detector has been upgraded in order to provide improved measurement of the scattered electron in deep inelastic scattering events. The centerpiece of the upgrade is a high{resolution lead/scintillating{ bre calorimeter.The main design goals of the calorimeter are: good coverage of the region close to the beam pipe, high angular resolution and energy resolution of better than 2% for 30 GeV electrons. The calorimeter should be capable of providing coarse hadronic energy measurement and precise time information to suppress out{of{time background events at the rst trigger level. It must be compact due to space restrictions.These requirements were ful lled by constructing two separate calorimeter sections. The inner electromagnetic section is made of 0.5 mm scintillating plastic bres embedded in a lead matrix. Its lead{to{ bre ratio is 2.3:1 by volume. The outer hadronic section consists of 1.0 mm diameter bres with a lead{to{ bre ratio of 3.4:1.The mechanical construction of the new calorimeter and its assembly in the H1 detector are described.
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