Recent status of the KamLAND experiment

Abstract The KamLAND experiment is a very long baseline reactor ν e oscillation experiment. This experiment has sensitivity to the oscillation parameters Δ m 2 > 10 −5 eV 2 and sin 2 2θ > 0.2, using reactor ν e which come typically from 170km away. This sensitive region completely covers the currently most favored MSW-LMA solution for the solar neutrino deficit problem. After 5 years of detector construction, the data taking started successfully in Jan. 2002. The detector performance is sufficient to perform reactor ν e physics and we expect the first physics result will come out soon. In this paper, the KamLAND detector, its expected sensitivities, history, and recent progress since the time of the conference, are briefly described.