Abstract :

The design of Panda - X, the first liquid xenon detector for Dark Matter Search in the JinPing lab in Szechuan Province, China is completed. A test set up will be filled aboveground for the first time before year end. The detector will then be installed in the underground location in early spring. This detector will initially have a modest size of about 25 kg fiducial. Independent of the results a more thorough search with a detector on the 1 ton scale is planned. A simple scale up of the standard liquid xenon double phase design requires too many compromises in the design. Besides the larger mass also a higher light collection efficiency, lower radio-active background, lower HV, less electronic channels and a lower maximum drift time are on the wish list for such a detector. At reasonable cost, it is impossible to improve all this parameters simultaneously with the same structure which was so successful in the XENON10 and XENON100 experiments. Some R&D for a new principle is needed. Once completed, the larger detector can be installed in the same environment as Panda-X, since outer cryostat vessel, the passive shield and the cryogenic system are already prepared for the larger size.