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Mine detection using time domain THz spectroscopy

The use of broadband techniques in the Terahertz (THz) region, has allowed us to probe the effectiveness of far-infrared waves to assess the penetration depths required for anti-personnel mine detection. Using THz-Time Domain Spectroscopy (THz-TDS) based methods we have probed the effective penetration depth of broadband THz pulses through soil samples collected locally in Ankara, Turkey. It was found that certain frequencies within the spectral range from 0.01 to 1THz were severely attenuated by both absorption and scattering effects dependent on the geometry and size of the particles inside the soil samples. For the most extreme case, the rocky soil sample exhibited severe attenuation of the frequencies above 0.1 THz. The measurements were repeated for wetted soil samples as well. From these results we have gained insight into the boundaries imposed by soil conditions on the detection of mines buried near and far beneath the surface. We found that the effective penetration depth is strongly affected by scattering effects and the dominant scattering mechanism is explained by Mie scattering for the soil samples in consideration rather than Rayleigh scattering.