Using a combination of aluminized Mylar reflectors, with strips of wavelength shifter evaporation and photo detector insensitive to UV-light, the longitudinal uniformity of +/- 8% is achieved for liquid Kr and Xe scintillators in pyromidal Mylar reflector cell with (4.2 x 4.2) x 37 x (2.2 x 2.2) cm5 dimensions. A response from glass-window photomultiplier is 7 photoelectrons/MeV for LKr and 9.5 photoelectrons/MeV for LXe along the cell.