Modifications to the original racetrack lattice concept as used in the feasibility study of the DIAMOND light source project are presented here. Double bend achromat structures with both 16 and 20 cells are described, with 4 fold superperiodicity. The production of higher brightness beams through lower emittance is achieved by optics solutions having finite dispersion in the long straights. The implications of insertion device minimum gaps and of the beam energy spread are discussed with reference to the specification of the radiation spectrum required by users. PROJECT BACKGROUNDIn 1998 the UK government announced that funding had been allocated for a new X-ray synchrotron source, to replace the existing SRS at the Daresbury Laboratory. These funds will be jointly provided by the Government and the Wellcome Trust, which has a remit to fund research in the life sciences. The announced funding covers the 3 year period from April 1999, but it is assumed that later allocations will cover the full 6 year project timescale.A review of the synchrotron radiation needs of the UK user community has recommended construction of a medium energy ring that complements the ESRF facilities in Grenoble; however for applications below about 50-100 eV an alternative national low energy source has been envisaged [1]. The 3 GeV DIAMOND design has demonstrated the feasibility of an X-ray synchrotron source at a scale suitable for the needs of the UK user community. Designed originally as a 16 cell double bend achromat (DBA) racetrack [2], this has now been modified to a 4 fold superperiodicity to obtain improved flexibility and a better dynamic aperture [3].Although a formal specification for DIAMOND is still in the process of being agreed, it is apparent that an important application of the facility will be in protein crystallography using samples of typical dimension 50µm and with very large cell dimensions. For this application high brightness photons at the selenium K-edge (12.7 keV) are essential, with energies up to about 20 keV also desirable, and several versions of the DIAMOND lattice have been studied to optimise performance against these criteria. High fluxes up to 50 keV will be provided by multipole wigglers (MPW), with energies beyond this available from high field insertions; DIAMOND is also well optimised for high brightness output in the soft X-ray region down to 100 eV or below. The extent to which even lower output energy (5-50 eV) can meet a defined user case is still under investigation, but will not alter the overall DIAMOND optimisation.Choosing between undulators or MPWs to deliver the required photon beams can have a significant influence on the facility specification, not least in the rf system demands. Additional factors are the ultimate minimum gap achievable with insertion devices and the electron beam energy. The study of these issues reported here indicates that a 3 GeV, 20 cell DBA lattice operated with finite dispersion in the long straights and with a circumference of about 400 m will produce...
Two new high field 2 T permanent magnet multipole wigglers have been installed into the SRS. This paper describes the effect of the new insertion devices on the SRS lattice. Closed orbit distortion, betatron tune change and emittance blow up have all been measured and the results are compared with lattice model predictions which are based on actual measured magnetic field values.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.