[en] The report describes a simple and reproducible 4π polythene geometry incorporating He³ detector for the calibration of neutron sources. The response of the system has been shown to be constant in the energy range of 2.1 MeV to 4.5 MeV, using radioactive neutron sources standardized with an improved manganese bath technique. A wide range of neutron sources having emission rates in the range 10³ to 10⁶ neutrons per/sec. can be calibrated using this detector with an accuracy of about 6%. It is expected that like the Precision Long Counter, this detector could serve as a secondary standard for the calibration of neutron sources. (author)