A new high-resolution soft x-ray beamline utilizing a variable line density grating has been constructed and tested at SRC. In addition to normal grating rotation, the grating housing mechanism allows a translation of the grating. This additional motion of the grating can be used in such a way that grating aberration effects such as defocus, coma, and spherical aberrations are minimized over the entire scan range. In order to achieve the theoretical resolving power of 105–5000 over the photon energy range of 280–1150 eV, extreme care had to be exercised in positioning and controlling the grating scan angle (<0.12 arcsec) and focus drive position (<10 μm). Using a spherical grating with a figure error of <0.2 arcsec and 10 μm slits, we were able to experimentally reproduce our theoretical predicted energy resolution over a wide energy range. We present photoabsorption data of the K-shell edges and associated Rydberg states of Ne, O2, and CO. The high-resolution monochromator unveils structures which were previously not seen or only poorly resolved. A quantitative data analysis of the Ne absorption peak shows the intrinsic lifetime broadening of the Ne 1s state agrees well with theoretical estimates.

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To increase the available photon flux density for users, alternate lattice tunings of the Aladdin synchrotron light source have been developed with horizontal emittances significantly lower than the present value of 127 π nmrad. Reduction of the horizontal emittance by a factor of three has been obtained experimentally. When the fourth harmonic Landau cavity is used to lengthen the bunch, the observed beam lifetime with the new lattice is not significantly changed from that of the existing lattice. The present goal is to achieve a factor of four horizontal and a factor of two vertical emittance reduction routinely. Progress in making this new configuration fully operational is discussed, including the use of quadrupole shunts with correction software for betafunction and dispersion correction, understanding of a mode coupling instability in higher-harmonic RF systems, RF clearing of ions, and fabrication of new optical monitoring stations.

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In collaboration with one of its user groups, the SRC has installed a new planar electromagnetic undulator (EMU) on the Aladdin storage ring. Field quality, and resulting radiation-performance of the device, are sufficiently close to the ideal that no shimming was required. With slight exception, only minor, anticipated adaptation onto the Aladdin ring was needed to meet strict operational requirements. Major details of the design, fabrication, ex-citu and in situ testing, and commissioning are presented. DESIGNThe EMU described here serves as a source for a high-resolution normal-incidence monochromator (NIM) beamline that covers the range from 6-40 eV [1]. The device was designed by SRC and constructed jointly with the Physical Sciences Laboratory (UW-Madison). The electromagnetic type was chosen for a number of reasons: favorable experience with a similar device for Iowa State University [2]; excellent field-quality control made possible with a copperiron geometry; and conventional construction that both uses inexpensive materials and enables in-house fabrication, leading to substantial cost savings.