Accuracy of an Atomic Microwave Power Standard (Conference digest)
  We have studied the accuracy of the atomic microwave power standard. The atoms are cooled and kept in a Magneto-Optical Trap (MOT), then dropped through a terminated transmission line (a rectangular, R-70 type, waveguide). The measurement of the internal atomic state allows an accurate determination of the transmitted microwave power. 
David C. Paulusse, Nelson L. Rowell and Alain Michaud