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Four years ago, on April 30, 2004, the Beijing Electron-Positron Collider (BEPC) finished its last high-energy physics experiment. That did not mean that it would be put out of service. Rather,640 million yuan ($93.8 million) would be spent upgrading it to BEPC Ⅱ, a collider 100 times more powerful. Now, the retool-ing process is about to be completed.