Nylon vessels installed and inflated

The two concentric nylon vessels of Borexino have been installed. After installation both vessels have been inflated with ultra-pure, humidified nitrogen gas. First step toward the completion of the detector: done!

In the following steps the gas will be first replaced by ultra-pure water, then in turn the water will be replaced with scintillator (PC+PPO) in the Inner Vessel, and with buffer solution (PC+DMP) elsewhere. The two solutions will have almost the same density to minimize buoyancy forces.