An important question in particle physics

astrophysics and cosmology is whether or not the rest mass of neutrino is exactly zero. Chooz experiment is a long-baseline search for the neutrino oscillations

which utilize a gadolinium-loaded liquid scintillation detector 300m underground and one kilometer from a large nuclear power station. It can probe Δm

2

values down to 1×10

-3

eV

2

for large sin

2

2θ values. Its total detection efficiency comes to 81% and the total error is about 3.7%-5.1%.