NJIT Physics Department Seminar

December 8th, Monday

Infrared and THz from Relativistic Electrons: NSLS-II and Beyond

Dr. Larry Carr

Brookhaven National Laboratory

(Condensed Matter Physics, Host: Sirenko)

**TALK**: ECE 202, 11:15am - 12:30pm (** NOTE SPECIAL TIME and NO TEA TIME **)

**LUNCH**: Tiernan 407, 12:30pm - 4pm

Abstract:

Relativistic electrons serve as a unique source of electromagnetic radiation, including the infrared and THz spectral ranges. The flattened Coulomb field combined with a uniform acceleration results in a highly directional emission. The spatially constrained electron beam in an accelerator results in a small effective source size such that long wavelengths are emitted from a diffraction-limited phase space. The result is a high-brightness source with well-defined polarization, and enables a variety of throughput-limited measurement methods such as microspectroscopy and spectroscopic ellipsometry.
In addition to producing electron beams with small transverse dimensions, modern linear accelerators are also capable of producing electrons in longitudinally short bunches. When this electron bunch length is less than the wavelength of interest, the electron emission is coherently enhanced. With electron bunches on the order of 100 fs, coherent THz pulses are produced with energies of hundreds of micro Joules.
This presentation will survey the long wavelength properties of synchrotron radiation, some IR measurement examples, and the infrared beamlines planned for the recently commissioned NSLS-II synchrotron light source. The use of very strong THz pulses from a linear accelerator to drive currents exceeding the critical value in a superconductor will also be presented