NSLS‐II: A proposed new synchrotron at Brookhaven National Laboratory
Synchrotron Radiation News
The National Synchrotron Light Source (NSLS) serves 2500 users per year, of which about 60% are affiliated with institutions in the Northeastern US. This makes the NSLS a vital resource for this strong research community, as well as providing essential scientific tools for strategic programs at Brookhaven National Laboratory (BNL), such as the BNL Center for Functional Nanomaterials, and neighboring universities and industries. The scientific productivity of the NSLS user community is very high
... munity is very high and has high impact, with ~ 700 publications per year of which ~ 150 appear in so-called premier scientific journals. The NSLS facility was designed in the late 1970s and consists of two 2 nd generation storage rings emphasizing the production of high flux synchrotron radiation from bending magnets. These rings were the first Double Bend Achromat (DBA) lattices in the world. The smaller 800 MeV VUV-IR ring covers the photon energy range from far infrared to soft x-ray. The X-ray ring operates at 2.8 GeV, with brightness several orders of magnitude higher than its design value. However, it is now at its theoretical limit and the horizontal emittance cannot be decreased significantly below its current value of 60 nm. Additionally, the 8-fold periodicity of the lattice severely limits the number of insertion devices (IDs), which are necessary for producing high brightness radiation. In order for the research of its formidable user community to continue to flourish, the NSLS needs to look beyond its existing machines. Today's most challenging and important problems at the scientific frontier demand photons with a broad spectrum of wavelengths and a broad range of dramatically enhanced capabilities, especially higher average brightness with nearly DC time structure, exquisite position stability, and easy energy tunability independent of other beamlines. The great majority of these problems require photons in the 5-20 keV energy range. These requirements are best met by an advanced 3 rd generation storage ring. Free electron lasers (FELs) are best suited for a special class of problems that require their ultra-high peak brightness and ultra-short pulses. While a machine based on the energy recovery linac (ERL) concept might have characteristics similar to storage rings, a long period of R&D will be necessary before it is established whether this approach is technically feasible  . Developments in storage ring technology make it possible to deliver: • Average brightness of 10 20 -10 21 photons/sec/0.1%bw/mm 2 /mrad 2 (10 4 gain over the present NSLS brightest beamline X25) • Average flux of 10 15 -10 16 photons/sec/0.1%bw (20x gain over present NSLS) Fig. 1 : The proposed NSLS-II, a highly optimized 3 rd generation storage ring, will be located directly across from the current NSLS building and the new Center for Functional Nanomaterials (CFN).