Over the past few years the scientific programs on sector 11 have evolved in new directions resulting in a mismatch between the capabilities of the existing beamlines and the experimental requirements. The elliptical multipole wiggler (EMW) which was originally chosen to allow high energy magnetic Compton scattering became the main obstacle to achieving high flux and small beam sizes. In fiscal year 2007 we got the opportunity to upgrade the source and beamlines, replacing the EMW with a new inline tandem configuration of one full length undulator A and a full length high energy undulator with a period length of 2.3 cm providing simultaneous high brilliance flux to all three stations. At the same time we are working on upgrades of monochromators and focusing optics for the medium energy and the high energy stations.
To reduce the disruption to the general user programs we decided to split the upgrade into three phases. In phase one starting in May 2007 the EMW was replaced by a single undulator A. All necessary shielding and essential optics improvement were performed. In a three month period we have commissioned the existing system and characterized the optics under the increased head load conditions. We have seen a major improvement of long term stability for all three stations and a significant increase of flux in 11-ID-B and 11-ID-D. The exact numbers depend on the precise experimental conditions but may be up to a factor of 40 better.
Phase two has just started with the installation of the high energy undulator and will end with the commissioning of the full beamline. The Undulator A will be limited to a minimum gap equivalent to k=2.11 (minimum energy of 4.5KeV) and the high energy undulator will be used at fixed closed gap. We expect that the beamline will be fully operational in November 2007. We have received all necessary safety approvals and are in the process of implementing changes to the monochromators. We look forward to starting the commissioning of these new powerful beamlines.
The third phase will be devoted to tailoring the optics and monochromators to the needs of the scientific programs of the three beamlines. Micro focusing and flexibility in the usage of focusing optics will be of major importance. An additional multilayer monochromator for 11-ID-D will allow making maximal use of the high flux provided by both undulators at selected energies. The design goals for this upgrade are shown in table 1 and a general overview of the optics is given in figure 1.
We look forward to welcoming you to these new beamlines and helping you to create exciting science.
|
|||
|
Figure 1: Schematic beamline layout of the 11-ID beamlines. The three stations are fed by a tandem inline Undulator configuration. The spatially overlapping spectrum of a full length Undulator A and an Undulator with 2.3 cm period can be utilized by the three stations simultaneously by all three end-stations. |
|
|||||||||||||||||||||||||
| Table 1: Design goals for the beamline upgrade after finishing phase III. |
|
|||
|
Figure 2: The EMW on its way out... hurrah!!! |