LBNL, Berkeley, California
Attosecond X-ray pulses are an invaluable probe for the study of electronic and structural changes during chemical reactions. The wide bandwidth of these pulses is comparable to that of the valence electronic states, and is well suited to probing valence electron excitations using core electron transitions. We investigate a method for creating two synchronized, attosecond soft X-ray pulses in a free electron laser, through optical manipulation of electrons located in two distinct sections of the electron bunch. Each X-ray pulse can have energy of the order of 100 nJ and pulse width of the order of 250 attoseconds. The central frequency of each X-ray pulse can be independently tuned to separate core electron transition frequencies of specific atoms in the molecule. The time interval between the two attosecond pulses is tunable from a few femtoseconds to a few hundred femtoseconds with a precision better than 100 attoseconds.
LBNL, Berkeley, California
At the Lawrence Berkeley National Laboratory, a high-brightness high-repetition rate photo-injector is under fabrication. The scheme is based on a normal conducting 187 MHz RF cavity operating in CW mode and capable of generating an electric field at the cathode plane of ~ 20 MV/m. The electron bunches will be accelerated to ~ 750 keV with peak current, energy spread and transverse emittance suitable for FEL and ERL applications. At the same time, the presence of a vacuum load-lock mechanism jointly with a vacuum system designed to operate in the 10 picoTorr range, will make of this injector a flexible cathode test facility. In particular, it will allow to use "delicate" high quantum efficiency cathodes to generate nC bunches at MHz repetition rate with present laser technology. Construction status and future plans are presented.
