David Harder

Stand-off Detection of Chemicals by UV Raman Spectroscopy

Experimental results are reported on a mobile, stand-alone, solar-blind ultraviolet (UV) Raman lidar system for the stand-off detection and identification of liquid and solid targets at ranges of hundreds of meters. The lidar is a coaxial system capable of performing range-resolved measurements of gases and aerosols, as well as solids and liquids. The transmitter is a flash lamp pumped 30 Hz Nd:YAG laser with quadrupled output at 266 nm. The receiver subsystem is comprised of a 40 cm Cassegrain telescope, a holographic UV edge filter for suppressing the elastic channel, a 0.46 m Czerny–Turner spectrometer, and a time gated intensified charge-coupled device (CCD) detector. The rejection of elastic light scattering by the edge filter is better than one part in 105, while the transmittance 500 cm−1 to the red of the laser line is greater than 50%. Raman data are shown for selected solids, neat liquids, and mixtures down to the level of 1% volume ratio. On the basis of the strength of the Raman returns, a stand-off detection limit of ∼ 500 g/m2 for liquid spills of common solvents at the range of one half of a kilometer is possible.

X-25 Cryo-ready In-vacuum Undulator at the NSLS

The existing 15‐year‐old hybrid wiggler at the NSLS has been replaced by a state‐of‐the‐art, cryo‐ready in‐vacuum undulator optimized for a dedicated macromolecular crystallography program. The device is a 1m long, 18mm period, hybrid PM‐type with a minimum operating gap of 5.6mm, and has provision for cryo‐cooling to 150K. Unlike the original SPring‐8 cryo‐PM undulator proposal, we use a new high‐remanence, high‐temperature grade of NdFeB (NEOMAX 42AH with Br=1.3T and Hcj=24 kOe) that can be baked to 100°C to be UHV‐ready in case of cooling system failure. A novel optical gap measurement system using a LED‐based product ensures gap accuracy of ±2 micro meter. A friction stir welding technique is used for the first time in an accelerator UHV device to minimize stress and deformation of the magnet arrays due to temperature gradients. This paper describes design issues of the device and other considerations such as magnetic measurement at low temperature.

Cryogenic Field Measurement of Pr2Fe14B Undulator and Performance Enhancement Options at the NSLS-II

Short period (14.5mm) hybrid undulator arrays composed of Praseodymium Iron Boron (Pr2Fe14B) magnets (CR53, NEOMAX, Inc.) and vanadium permendur poles have been fabricated at Brookhaven National Laboratory. Unlike Neodymium Iron Boron (Nd2Fe14B) magnets which exhibit spin reorientation at a temperatures below 150 K, PrFeB arrays monotonically increase performance with lower operating temperature. It opens up the possibility for use in operating a cryo‐permanent magnet undulator (CPMU) in the range of 40 K to 60 K where very efficient cryocoolers are available. Magnetic flux density profiles were measured at various temperature ranges from room temperature down to liquid helium (LHe) using the Vertical Testing Facility (VTF) at the National Synchrotron Light Source‐II (NSLS‐II). Temperature variations of phase error have been characterized. In addition, we examined the use of textured Dysprosium (Dy) poles to replace permendur poles to obtain further improvement in performance.

Insertion Devices at the National Synchrotron Light Source-II

The NSLS-II storage ring completed commissioning in 2014 and all project-beamline IDs have also been commissioned. As of February 2015, six beamlines are about to finish commissioning. By the end of 2015, the ring is expected to store 300 mA with top-up injection capability and 500 mA with a second superconducting RF cavity installed in the following year. The design principle of the NSLS-II ring is to employ low-field BMs and simultaneously install high-field wigglers in non-dispersive straights to reduce the horizontal emittance. The more wigglers are installed, the smaller the horizontal electron beam emittance becomes. At this stage, six 3.4-m-long wigglers with 1.8 T effective field and 100 mm period length have been installed in three straight sections, which could reduce emittance in a bare lattice from 2.1 nm.rad to approximately 1.0 nm. rad. Two 2.0-m-long EPU49s are installed for the coherent soft X-ray (CSX) beamline in a short straight (SS) section also known as the low-βx straight section. These are Apple-II-type devices with four movable arrays. Two 3.0-m-long IVU20s are installed in two SSs, one for the Hard X-ray Nano-Probe (HXN) beamline and the other for the Coherent Hard X-ray (CHX) beamline. One 1.5-m-long IVU21 is installed in a canted short straight section for the Sub-Micron Resolution X-ray Spectroscopy (SRX) beamline. Its canting angle is 2 mrad outboard in the center of the straight section. The first ID for this beamline is installed in the downstream portion of the straight section. Another 3.0-m-long IVU22 is installed in a long straight section (LS: high-βx) where a second device is planned to be added in the future. Three 2.8-m-long IVU23s are planned to be installed in long straight sections, either in an asymmetric canted configuration or in a straight configuration. One 1.4 m EPU57 and one 2.8 m EPU105 are planned for the Electron Spectro-Microscopy (ESM) beamline in a SS, while one 3.5m EPU57 in a LS is planned for the Soft Inelastic X-ray Scattering (SIX) beamline. Table 1 shows the specifications of all the IDs funded so far.

Insertion device R&D for NSLS-II

NSLS-II is a medium energy storage ring of 3 GeV electron beam energy with sub-nm.rad horizontal emittance and top-off capability at 500 mA. Damping wigglers will be used not only to reduce the beam emittance but also for broadband sources for users. Cryo-permanent magnet undulators (CPMUs) are considered for hard X-ray planar device, and permanent magnet based elliptically polarized undulators (EPUs) are for soft X-ray polarization control. Rigorous R&D plans have been established to pursue the performance enhancement of the above devices as well as building new types of insertion devices such as high temperature superconducting wiggler/undulators. This paper describes the details of these activities and discuss technical issues.

Refurbishment of a used in-vacuum undulator from the National Synchrotron Light Source for the National Synchrotron Light Source-II ring

The National Synchrotron Light Source (NSLS) ceased operation in September 2014 and was succeeded by NSLS-II. There were four in-vacuum undulators (IVUs) in operation at NSLS. The most recently constructed IVU for NSLS was the mini-gap undulator (MGU-X25, to be renamed IVU18 for NSLS-II), which was constructed in 2006. This device was selected to be reused for the New York Structural Biology Consortium Microdiffraction beamline at NSLS-II. At the time of construction, IVU18 was a state-of-the-art undulator designed to be operated as a cryogenic permanent-magnet undulator. Due to the more stringent field quality and impedance requirements of the NSLS-II ring, the transition region was redesigned. The control system was also updated to NSLS-II specifications. This paper reports the details of the IVU18 refurbishment activities including additional magnetic measurement and tuning.

Recent Magnetic Measurement Activities at NSLS-II Insertion Device Laboratory

National Synchrotron Light Source II (NSLS-II) at Brookhaven National Laboratory (BNL) is a new 3 GeV third generation electron storage ring designated to provide extremely intense beams of X-ray, ultraviolet, and infrared light for basic and applied research. Insertion devices (IDs) play a significant role in achieving the high performance demands of NSLS-II. An accurate magnetic characterization and proper corrections of these devices are essential activities in the development of a state-of-the-art light source facility. This paper describes the results of the latest magnetic measurement activities at the NSLS-II ID laboratory.