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National Synchrotron Light Source

The National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory (BNL) in Upton, New York is a national user research facility funded by the U.S. Department of Energy (DOE). The NSLS, is considered a second generation synchrotron, and was built beginning in 1978 and finished in 1984.[2]

The NSLS experimental floor consists of two electron storage rings: an X-Ray ring and a VUV (Vacuum Ultra Violet) Ring which provide intense focused light spanning the electromagnetic spectrum from the infrared through x-rays. The properties of this light and the specially designed experimental stations, called beamlines, allow scientists in many fields of research to perform experiments not otherwise possible at their own laboratories.

History

Ground was broken for the NSLS on September 28, 1978. The vacuum ultraviolet (VUV) ring began operations in late 1982 and the x-ray ring was commissioned in 1984. In 1986, a second phase of construction expanded the NSLS by 52,000 square feet (4,800 m2). This added offices, laboratories and room for new experimental equipment.[2]

During the construction of the NSLS, two scientist Renate Chasman and G. Kenneth Green invented a special periodic arrangement of magnetic elements, a so-called magnetic lattice, to provide optimized bending and focusing of electrons.[2] The design called the Chasman–Green lattice, and it is the basis of design for every synchrotron storage ring. It is common to refer to storage rings by the number of straight sections and bend sections. The bend sections, produced more light than the straight sections due to the change in angular momentum of the electrons. Yet, Chaseman and Green accounted for this in their design by adding wigglers and undulators in the straight sections of the storage ring,[2] this resulted in very bright light also being produced by these sections. In fact these insertion devices, wigglers and undulators, produce the brightest light. Beamlines that are downstream from these insertion devices receive the brightest light.

VUV ring
A beamline for synchrotron light at Brookhaven.

The VUV Ring at the National Synchrotron Light Source was one of the first of the 2nd generation light sources to operate in the world. It was initially designed in 1976 and commissioned in 1983.[3] During the Phase II upgrade in 1986, two insertion wigglers/undulators were added to the VUV ring providing the highest brightness source in the vacuum ultra-violet region until the advent of 3rd generation sources.[3]

X-ray ring

The X-ray ring at the National Synchrotron Light Source was one of the first storage rings designed as a dedicated source of synchrotron radiation.[4] The final lattice design was completed in 1978 and the first stored beam was obtained in September 1982. By 1985 the experimental program was in a rapid state of development, and by the end of 1990 the Phase II beamlines and insertion devices were being brought into operation.[4]

Design

Electrons are the generators of the synchrotron radiation that is used at the end stations of beamlines. The electrons are first produced by a 100KeV triode electron gun.[5] These electrons then procceed through a linac, linear accelerator, which gets them up to 120MeV.[5] Next, the electrons enter a booster ring, where they are increased to 750MeV,[5] and are then injected into either the VUV ring or the X-ray ring. If they enter the VUV ring they are ramped up further to about 825MeV and if they enter the X-ray ring they are ramped to 2.800GeV.

Once in the ring, VUV or X-ray, the electrons orbit and lose energy as a result of changes in angular momentum which cause the expulsion of photons. These photons are deemed white light, i.e. polychromatic, and are the source of synchrotron radiation. To get a single and fixed wavelength at the end station, a monochromator is used. Yet prior to entering the monochromator the light is collimated.

As mentioned above, during normal operations the electrons in the storage rings lose energy and as such every 12 (X-ray ring) and 4 (VUV ring) hours the rings must be re-injected. The difference in time arises from the fact that VUV light has a bigger wavelength and thus has lower energy which leads to faster decay, while the X-rays have a very small wavelength and are high energy.

Facilities

There is a UV ring and a X-ray ring. The UV ring has 19 beamlines (13 are operational) and the X-ray ring has 58 beamlines (51 are operational).[6] The beamlines are operated and funded in numerous ways, yet the NSLS is a user facility and as such any scientist that submits a proposal can be granted beam time. There are two types of beamlines at the NSLS: Facility Beamlines (FBs), of which there are 18; and Participating Research Team (PRT) beamlines, currently totaling 46. FBs are operated by the NSLS staff and reserve a minimum of 50 percent of their beam time for users and PRT beamlines reserve 25 percent of their beam time for users.

Each X-ray beamline has an end station called, a hutch, these are large enclosures made of lead to protect the users from the ionizing radiation of the beam. On the X-ray floor, many of the experiment conducted use techniques such as XRD, XAFS, DAFS (X-ray diffraction anomalous fine structure), WAXS, and SAXS.

On the UV-ring, the end stations are usually UHV (ultra high vacuum) chambers that are used to conduct experiments like XPS, UPS, LEEM and NEXAFS.

Usually in every beamline there are other analytical tools such as, a MS or a GC-MS. These techniques help supplement and better quantify the experiments carried out at the end station.

Achievements and statistics

Nobel prize

In 2003, Roderick MacKinnon won the Nobel Prize in Chemistry for deciphering the structure of neuronal ion channel, his work was in part conducted at the NSLS.[7]

User statistics

The National Synchrotron Light Source hosts more than 2,200 users from 41 U.S. states and 30 other countries every year.[8] Just in 2009, there were 658 journal publications and 764 total publications including; journal publication, books, patents, thesis, and reports.[9]

NSLS-II

Between 2013 and 2015, the NSLS will be phased out of operation after more than 30 years of service.[10] It will be replaced by the NSLS-II, which is designed to be 10,000 times brighter.[10]