  A very efficient method to measure the flux of Ultra-high energy (UHE)
neutrinos is through the detection of radio waves which are emitted by the
particle shower in the lunar regolith. The highest acceptance is reached for
radio waves in the frequency band of 100-200 MHz which can be measured with
modern radio telescopes. In this work we investigate the sensitivity of this
detection method to structures in the UHE neutrino spectrum caused by their
absorption on the low-energy relic anti-neutrino background through the Z-boson
resonance. The position of the absorption peak is sensitive to the neutrino
mass and the redshift of the source. A new generation of low-frequency digital
radio telescopes will provide excellent detection capabilities for measuring
these radio pulses, thus making our consideration here very timely.
