  We present measurements of superconducting flux qubits embedded in a three
dimensional copper cavity. The qubits are fabricated on a sapphire substrate
and are measured by coupling them inductively to an on-chip superconducting
resonator located in the middle of the cavity. At their flux-insensitive point,
all measured qubits reach an intrinsic energy relaxation time in the 6-20
microseconds range and a pure dephasing time comprised between 3 and 10
microseconds. This significant improvement over previous works opens the way to
the coherent coupling of a flux-qubit to individual spins.
