[en] A new method of determination of the double beta decay probability is proposed. The method is based on present-day experimental achievements, in laser technology, mass-spectroscopy and it uses the developed method of separation and detection of ultrasmall quantities of inert gases that is already used in the Davis experiments on solar neutrino detection. The essence of the method is as follows: before the experiment the detector is cleaned of stable krypton and xenon isotopes by washing with ultra-pure hydrogen or helium. After holding the detector underground within a year crypton and xenon produced inside the detector after double beta decay are separated and their concentration and isotopic composition are measured. The analysis of different background factors shows the possibility of measuring the double beta decay probability up to 10^-33 - 10^-34 s^-1 and less in case of need