Ultrasound-induced echoes and quantum beats observed in the nuclear exciton decay utilizing synchrotron radiation

Abstract The time evolution of the free decay of the nuclear exciton induced by E = 14.413 keV synchrotron radiation pulses was observed with a system of two stainless-steel absorbers containing 57 Fe. In between these foils the radiation was Bragg scattered from a vibrating quartz crystal. The ultrasound modulated radiation field leads to echo-spikes or echo-dips in the decay of the nuclear exciton. In case of relative Doppler motion between both foils with a constant velocity we observe quantum beats that are concentrated in the echoes.