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.