BECOLA commissioning tests with bunched beams

The Beam Cooling and Laser spectroscopy (BECOLA) facility has been fully realized at NSCL and performance tests were completed with a stable $^{39}$K ion beam extracted at 29.7 keV from an off-line ion source. The $^{39}$K ions were cooled, bunched and subsequently neutralized by charge exchange with Na vapor. Laser light was co-propagated with the neutral $^{39}$K beam and the laser frequency was Doppler-tuned into resonance by adjusting the velocity of the $^{39}$K ions. The fluorescence induced by the laser probing of the $^{39}$K atomic beam was collected in a photomultiplier. A newly-developed DAQ system, which integrates a FPGA-based time-resolved scaler into a real-time acquisition system, was used to record the observed fluorescence as a function of both time and ion velocity.