Development of a car-borne <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" altimg="si0001.gif" overflow="scroll"><mml:mi mathvariant="normal">γ</mml:mi><mml:mi mathvariant="normal">-</mml:mi><mml:mi>ray</mml:mi></mml:math> survey system, KURAMA