TPC in magnetic field had been proposed to search for the neutrinoless
double beta decay of the different isotopes. First stage of this prog
ram was the prototype TPC with volume 0.3m(3). Nd-150 2 beta 2v decay
with half-life time T-1/2(2 beta 2v) = (1.88(-0.39)(+0.69) +/- 0.19).
10(19) years was observed. There was shown the powerful ability of the
track experiment to suppress the background. The rejection factor k >
10(7) was obtained at the laboratory on the sea level. The large setu
p (TPC with volume 13m(3) in the magnet with diameter d=5.5m) is under
construction.