Development of Gaseous Tracking Devices for the Search of WIMPs
  The Time Projection Chamber (TPC) has been recognized as a potentially powerful detector for the search of WIMPs by measuring the directions of nuclear recoils, in which the most convincing signature of WIMPs, caused by the Earth's motion around the Galaxy, appears.   We report on the first results of a performance study of the neutron exposure of our prototype micro-TPC with Ar-C$_2$H$_6$ (90:10) and CF$_4$ gas of 150 Torr. 
H. Sekiya, K. Hattori, S. Kabuki, H. Kubo, K. Miuchi, T. Nagayoshi, H.   Nishimura, Y. Okada, R. Orito, A. Takada, A. Takeda...