THz radiation enables probing and controlling low-energy excitations in matter such as molecular rotations, DNA dynamics, spin waves and Cooper pairs. In view of the growing interest in the THz radiation, the Stockholm-Uppsala centre for Free Elektron Laser research, SUFEL, together with the FREIA Laboratory is studying the national user interest in THz physics and working on a conceptual design of a compact multicolor photon source. The ultimate goal is to build a versatile THz/X-ray source for a multidisciplinary national user facility at the FREIA laboratory of Uppsala University. The photon source will be driven by high-brightness electron bunches produced by a superconducting linear accelerator (SC linac). In particular, we aim to combine an envisioned THz FEL with an X-ray source and such a combination will provide an opportunity for the time-resolved pump (THz)−probe (X-ray) measurements.
Implementation of superconducting technology would greatly enhance the flexibility of the envisioned multicolor photon source. Superconducting linacs enable operation in continuous wave (CW) or quasi-CW mode, which implies higher average brightness of the source. With a high duty factor operation, an SC linac also reduces the overall size of the facility and is economically more efficient than its normal conducting counterpart.