Project of the low background detector BiPo

The low-background detector assigned to search the weak radioactive pollution by the 208 Tl and 214Bi in thin samples with the big area is described. Samples are the 12 m2 foil-sources, made of enriched isotopes, 82 Se or 150Nd. Such samples are planned to use in the investigation of the neutrinoless double beta-decay in the SuperNEMO experiment. The principle of the detector operation is based on the registration of the delayed beta-alpha coincidence from the uranium and thorium radioactive chains. Sensitivity of the detector is planned to be at the level of: 208Tl < 2 μBq/kg and 214Bi < 10 μBq/kg. Alternative variants of the detector are described. The first results obtained by means of the prototype detector, operated in the underground laboratory Frejus, France, are presented