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Strong-Field THz Behavior of Superconductors in the Time-Domain and IR/THz Beamline Development at NSLS-II

Strong-Field THz Behavior of Superconductors in the Time-Domain and IR/THz Beamline Development at NSLS-II
place:new ANKA seminar room, building 348, upper floor
Affiliation:Photon Sciences, Brookhaven National Laboratory
Date:07.07.2014
Inviting person:Yves-Laurent Mathis, KIT-ANKA
Speaker:G. Lawrence (Larry) Carr
Time:14:00 p.m.

Abstract:

This presentation will cover two aspects of long wavelength radiation from relativistic electrons at Brookhaven.  The 1st portion will discuss our analysis results for the response of superconducting NbN films to a very strong coherent THz pulse, produced as transition radiation in a photoinjected linac.  The THs pulse is sufficient to drive supercurrents in excess of the critical density.  Using the known properties of a superconductor carrying a supercurrent, we develop a time-domain analysis that indicates the superconducting state collapses on a 100 fs (or faster) time scale, more than 100 times faster than the equilibrium inelastic scattering time of ~15ps. The second portion will be a description and status update of the NSLS-II project and the first planned beamline for infrared and THz, called FIS/MET.  This beamline is being designed to span the photon energy range from 0.25 meV to 5 eV for spectroscopy of materials, including under extreme conditions.  Plans are developing for a second infrared beamline, dedicated to mid-IR spectroscopic imaging.