Investigation of double-beta-decay of Mo-100 with the liquid-argon ionization chamber

The experiment is located in the Gran Sasso Underground Laboratory (3500 mw e), The full weight of the Mo-100 under investigation is 138.7 g, Three mea surement runs were done (202, 238 and 313 h), As a result, the limits of ha lf-lives for 0 nu and 0 nu chi(0) decays of Mo-100 were obtained as 3.5 x 1 0(21) and 1.2 x 10(20) yr, respectively, at 90% C.L. Some extra events in t he energy region 1.6-3 MeV lead to a preliminary result on the 2 nu beta be ta decay of Mo-100, about 8.5 x 10(18) yr. We plan to improve the backgroun d conditions of the experiment and increase the sensitivity to (1-2) x 10(2 3) yr for 0 nu decay mode and to (1-2) x 10(22) yr, for the 0 nu chi(0) dec ay, In addition, we hope to investigate the 2 nu decay mode of Mo-100 with an accuracy of about 10%.