Working characteristics of the New Low-Background Laboratory (DULB-4900)

The Baksan Neutrino Observatory (BNO) of Institute for Nuclear Research of the Russian Academy of Science is one of major old underground laboratories in the world for experiments in the field of a nuclear physics, particle and astroparticle physics. A concise technical characteristic of a new lowbackground laboratory DULB-4900 of the BNO is presented. The laboratory is located at a distance of 3700 m from the main entry to the Observatory tunnel, in the hall of 6 6 40 m 3 . Thickness of the mountain rock over DULB corresponds to 4900 m:w:e:, thereby decreasing cosmic ray flux by 10 7 times. The technique and the results of background measurements in the Hall, ordinary box and low-background box are presented. 222 Rn contamination in the laboratory air has been measured by direct detection of -radiation of its daughter 214 Bi distributed over the volume of the lowbackground box. The results of the data analysis are presented.