text: A variant of this experiment used atoms of rubidium-57 and rubidium-87 with a standing wave tuned resonantly to the rubidium D1-line.
full_question: A variant of this experiment used atoms of rubidium-57 and rubidium-87 with a standing wave tuned resonantly to the rubidium D1-line. Another variant of this experiment fired a Scout D rocket from Wallops Island, with an atomic hydrogen maser on board. Modified in the Vissot-Levine experiment, this study used the cone of a loudspeaker to vary the frequency of photons with initial energies of 14.4 kilo-electron volts, and was based on the principle that atoms cannot absorb photons emitted by the same species if they have been Doppler-shifted. Relying on the Mossbauer effect, this experiment used a helium-filled Mylar bag placed between two iron-57 samples and measured gravitational redshift. For 10 points, name this study conducted in the tower of Harvard's Jefferson Laboratory to verify general relativity.
first_sentence: A variant of this experiment used atoms of rubidium-57 and rubidium-87 with a standing wave tuned resonantly to the rubidium D1-line.
raw_answer: Pound-Rebka experiment