An array of eight large BC-501A liquid scintillators for use in neutron Time-Of-Flight (TOF) experiments was build. The array of neutron detectors MONA has been tested in the measurement of neutron spectra from spontaneous fission of ²⁵²Cf. The detector was also used to measure neutron spectra originated in the experiment at Warsaw Cyclotron. The neutron spectra from the heavy ion collision of ¹²C + ⁸⁹Y system were measured at six selected angles by TOF method at average laboratory energy of 49.5 MeV. In order to extract primary neutron spectrum the unfolding procedure was applied. The temperature of the source was determined through off-line analysis and was found to be 1.62 MeV. The level density parameter a, was determined within the framework of a Fermi-gas model, to be equal to a = A/9.4.