Efficient 1.8 t high-efficiency scintillation counter for neutron detection

Specific features and the principle of operation of a liquid scintillation counter designed for the detection of neutrons generated in showers due to inelastic scattering of cosmic ray muons are described. The detector consists of three rows of scintillation counters-modules by four modules in every row. Each module is scanned by two photomultipliers of the 49 type that extend to the windows out of plexiglass. The counter is filled with liquid organic scintillator based on white spirit with additives of 1g/1 PPO (2.5-diphenyloxazole) and 0.03 g/1 POPOP (1.4-di-[2-(5-phenyloxazole)]benzene) with 2.4 g/l Gd octoate dissolved in it. The volume of the counter is 1800 l, the area is 2 m2, it contains 1.8 t of organic scintillator. The general view of the counter is shown, the block-diagram for measuring neutron detection efficiency is presented. The efficiency of neutron detection measured with the aid of 252Cf placed in the centre of the counter is (83 +- 1)%