Les Dallin

Photoacoustic spectroscopy using coherent synchrotron radiation: application to α-lactose monohydrate

We produced coherent synchrotron radiation at the Canadian Light Source between about 5 and 30 cm(-1) in bursting and continuous emission modes and used it to acquire photoacoustic spectra of solids. A band was observed in the spectrum of α-lactose monohydrate at 18 cm(-1) and attributed to a rotational mode, in agreement with published data obtained using other numerical and experimental techniques.

25+2 poles, 4.3 T wiggler at BMIT – 7 years operational experience

The research program at the Biomedical Imaging and Therapy (BMIT) Facility at the Canadian Light Source (CLS) required a unique radiation source that would provide a wide beam fan with high critical energy and high dose rates. A superconductive wiggler was the only practical solution that could be installed inside the CLS ring. Design requirements were defined in 2005 [1-2]. The wiggler, optimized for a 3 GeV ring, was to match operating parameters of an equivalent hard X-ray source on a 6 GeV ring. Manufacturing started in 2006 and the wiggler was installed in November of 2007 [3-5]. Several modifications to external hardware and to the power supplies’ controls were implemented to address the air leaks into the He space and to provide the ability to change the field of the wiggler during normal operation without affecting other research groups. The original burst disk and pressure relief valves were replaced with commercial units. Most of the buna O-rings were replaced with metal O-rings, helping to prov...

EPU correction scheme study at the CLS

The Canadian Light Source (CLS) Quantum Materials Spectroscopy Center (QMSC) beamline will employ a novel double period (55 mm, 180 mm) elliptically polarizing undulator (EPU) to produce photons of arbitrary polarization in the soft X-ray regime. The long period and high field of the 180 mm period EPU will have a strong dynamic focusing effect on the storage ring electron beam. We have considered two partial correction schemes, a 4 m long planar array of BESSY-II style current strips, and soft iron L-shims. In this paper we briefly consider the implementation of these correction schemes.

Towards a 4th generation storage ring at the Canadian Light Source

Demands from beamline scientists for more brilliant sources of synchrotron radiation have resulted in the emergence of 4th generation (diffraction-limited) storage rings. The practical development of the multi-bend achromat (MBA) concept by MAX IV lab has spurred many synchrotron light sources around the world to develop similar machines. For existing facilities two options are available: upgrading existing machines or building a new structure. The Canadian Light Source (CLS) has explored both options. For a new low emittance source in the existing CLS tunnel a decrease in electron energy would be required. A machine similar to the ALS upgrade could be contemplated. To achieve low emittance at our present energy of 2.9 GeV a new storage ring is desirable. Several options have been investigated. These designs use extremely strong focusing magnets to achieve extremely low emittances in compact lattice achromats.

Simulated and Measured Magnetic Performance of a Double APPLE-II Undulator at the Canadian Light Source

Assembly and shimming are underway for a double APPLE-II type undulator (two magnet arrays installed side by side on a single support structure) at the Canadian Light Source. The device is planned to be installed in spring 2017. Extensive preparation was done prior to assembly, particularly in the development of a simulated annealing algorithm for magnet virtual shimming, as well as assembly procedures that minimized positional errors in the installed magnet blocks. In this paper we present measurements taken throughout shimming the first elliptically polarizing undulator (EPU), and compare with predictions from a RADIA [1] model where each magnet block was magnetized uniquely according to individual Helmholtz coil measurements.

A phase-space beam position monitor for synchrotron radiation

A system has been developed to measure the vertical position and angle of the electron beam at a single location from a synchrotron source. The system uses a monochromator tuned to the absorption edge of a contrast material and has a sensitivity comparable with other beam position monitors.

Global Orbit Feedback System Upgrade At The Canadian Light Source

The Canadian Light Source has been using a Matlab application called CLSORB to perform slow orbit correction in the storage ring. A fast global orbit feedback system is recently deployed to replace the old system. The correction rate is about 45 Hz and all the corrections are calculated and applied by an RTEMS IOC. This upgrade has resulted in increased beam stability and reduced perturbations caused by the ramping of superconducting wigglers. This paper will discuss the implementation and performance of the fast orbit correction system.

Observation of Multi‐bunch Interference with Coherent Synchrotron Radiation

The observation of Multi‐bunch interference with coherent synchrotron radiation at the Canadian Light Source is discussed along with the possibility that some of the spectral features are driven by the radiation impedance of the vacuum chamber.

Coherent synchrotron radiation measurements in the THz region at the CLS far infrared beamline

Synchrotron radiation (SR) in the far infrared region is used for high spectral resolution experiments at the Canadian Light Source (CLS). Although SR photon flux can exceed that of thermal sources at long wavelengths, a further increase in flux is obtained by shortening electron bunch lengths to the order of far infrared wavelengths. When shortened, the electron bunch photon output is boosted by coherent summation of the synchrotron radiation (CSR). Accelerator parameters were adjusted for short bunch lengths and CSR in burst mode at the Far Infrared beamline was observed. Preliminary results are discussed in the 5 to 40 cm-1 region (0.15 to 1.2 THz). Several unexpected features have been observed in the spectral energy curve at resolutions below 0.1 cm-1 (3 GHz). A theoretical model locating the spectral intensity peaks at high spectral resolution indicates that vacuum chamber geometry and side wall impedance effects may be responsible. A spectrum of nitrous oxide was obtained using the CSR.