Abstract—We demonstrate a prototype of a laser-cooled 87Rb fountain clock. We report a preliminary measurement of the frequency shift due to cold collisions and find the shift to be at least a factor of ten less than that in a laser-cooled Cs clock. We also demonstrate the use of the ac Zeeman shift to measure the response of a microwave cavity. Finally, we have demonstrated a juggling atomic fountain and discuss the application of this technique to fountain and microgravity atomic clocks. Index Terms—Atomic clock, microwave resonators, microwave spectroscopy, rubidium materials/devices. I.