Duchess rad

The radiometric, or gamma-ray spectrometric method, measures the natural variations in the gamma-rays detected near the Earth�s surface as the result of the natural radioactive decay of potassium, uranium and thorium. The data are collected on airborne geophysical surveys conducted by Commonwealth, State & NT Governments and the private sector.

放射测量法（又称伽马射线能谱法）可测定地球表面附近探测到的伽马射线的自然变化，此类伽马射线源于钾、铀与钍的天然放射性衰变。该数据集由英联邦、各州及北领地政府与私营机构开展的航空地球物理勘探项目采集所得。