Group velocity in a nuclear EIT-like Λ scheme and comparison with optical EIT

The group velocity of gamma radiation scattered in the forward direction by a nuclear lambda scheme experiencing level mixing induced transparency, which shows some similarity to optical EIT, has been investigated. The equations for the nuclear coherences governing the group velocity have been solved. The group velocity decreases with the density of the resonant nuclei and with a decrease in the intensity of the mixing interaction. A comparison between the group velocity of the gamma radiation and the probe radiation in “classical” optical EIT conditions has been made.