"Big Light" Free-Electron Laser Initiative
Five workshops, four years, and $2 million later, the design of the "Big Light" free electron laser (FEL) is complete and the Magnet Lab is moving forward with a proposal to construct a fourth-generation terahertz (THz) light source alongside its DC magnet facility at Florida State University.
The input of FEL experts, as well as physicists, chemists and biologists from around the U.S. and Europe, have defined specifications that offer unprecedented brightness, time-resolution and continuous tunability over the entire terahertz frequency range (roughly 0.3-300 THz).
To minimize costs and time to "first light," the FEL design developed by Jefferson Laboratory assembles components of proven technology – brought together in a novel configuration to provide several unique features:
- Three co-located narrow-band light sources with overlapping frequency ranges
- Co-location of a fourth source, a THz broad-band source
- Ultra-fast THz light pulses (1 psec pulses with a 10 MHz rep rate)
- Ultra-bright THz light pulses (1 million times brighter in the THz regime than third-generation synchrotrons)
- Automatic time-synchronization of near IR, mid-IR and broadband THz sources (< 20 fsec jitter for pump-probe experiments)
The design involves a photo-injected 60 MeV linac for high efficiency, low operating costs and eventual potential enhancement to higher beam-current operation (the initial planned beam current is 3 mA). The FEL is designed in an energy recovery configuration (ERL), the primary benefit for a user facility being the absence of a radioactive beam dump, which in turn means that the accelerator vault can be entered at short notice to perform maintenance and adjustment.
There are three FEL undulators. One, the far-infrared (FIR) FEL, is driven by the injector; the mid-infrared (MIR) and near-infrared (NIR) FELs are in the ERL loop and can be run simultaneously using the same electron bunches. The broadband THz source is also situated within the ERL loop, so that time-correlated pulses from NIR, MIR and THz sources can be used in multi-color experiments.
Research Using Magnetic Fields
The Big Light source will permit new and enhanced (magneto) optical spectroscopies, pump-probe measurements, pico-second time-resolved experiments, nonlinear absorption and multi-photon techniques across the same frequency range as the orbital, spin and nuclear quantization provided by the intense magnetic fields at the Mag Lab. Other newly enabled experiments will be founded upon the internationally recognized expertise in microscopy, nuclear magnetic resonance (NMR) and Fourier-transform ion cyclotron resonance (FT-ICR) that already exists at the Magnet Lab.
The FEL will make visible phenomena that have been hidden
by a "blind spot" in the electromagnetic spectrum.
The Big Light FEL will be world-unique even without utilizing the Mag Lab's magnetic fields. The Mag Lab's experience running a first-rate user support infrastructure will benefit both high-field and zero-field experiments in Big Light's user program.
- Quantum matter: resonant spectroscopy of low-energy correlated states, electron spin resonance of d- and f-electron systems, cyclotron resonance of m*~1 systems to 45 tesla, ESR to 1.25 THz with T2 times as short as 1 nanosecond, qubit characterization and manipulation
- Nanoscience: Scanned-probe optical nanoscopy for imaging nano-scale phase separation and performance of new superconducting materials
- Energy: Sold-state chemistry for catalysis and energy storage, f-electron chemistry for radioactive waste mitigation
- Complex fluids: infrared multi-photon dissociation for selective bond breaking, mass spectroscopy for petroleum analysis
- Macromolecules: multi-frequency dynamics via spin labelling, vibrational mode coupling via Raman spectroscopy
- Biomedicine: nanoscale dynamic imaging of tissue via coherent anti-stokes Raman scattering
As part of its NSF mission, the Magnet Lab strives to enhance existing and create new experimental techniques in response to scientific opportunities. The addition of Big Light to the nation's research tools will provide transformational(!) research opportunities in materials, biomolecules and more. For more in-depth and up-to-date information concerning Big Light, please see Scientific Case and Engineering Design for "Big Light".
For more information contact EMR program director Stephen Hill.
