At Bell Telephone Laboratories (Murray Hill / Berkeley Heights, New Jersey), Daryl Chapin, Calvin Fuller, and Gerald Pearson developed the first practical silicon photovoltaic cell capable of converting sunlight into usable electricity at a conversion efficiency of about 6%, compared to the ~1% achieved by earlier selenium cells. It was publicly demonstrated on April 25, 1954. The discovery emerged partly by accident during research into doped silicon semiconductors (gallium + lithium bath) for transistor development. This cell was the prototype for those that would later power satellites (starting with Vanguard 1 in 1958) and, later, the modern photovoltaic industry.