The first part of this thesis is devoted to the development of a large array of neutron detectors NEDA (NEutron Detector Array) and their conceptual design using Monte-Carlo simulations. Prior to the development of NEDA, the neutron detection with liquid scintillators is discussed in Chapter 2. In Chapter 3, the design criteria and simulations of NEDA are discussed. NEDA aims to build a neutron detector array with high efficiency, based on liquid scintillators. NEDA will be coupled to the high-purity γ-ray detector arrays, like AGATA, EXOGAM, to be used as a trigger or complementary detector in the contemporary nuclear physics experiments, which aim to investigate the structure of the exotic nuclei. The importance of NEDA is related to its capability to filter the reaction channels including multiple neutron evaporation with high efficiency. The simulations of the conceptual design of NEDA for the near-future campaign at GANIL are presented. The NEDA detectors together with the Neutron Wall promise up to 7.62(11)% and 1.89(11)% efficiencies for two- and three-neutron detection comparing to the Neutron Wall standalone 3.93(10)% and 0.55(14)%, respectively. The results of this study has been published in The European Physical Journal - Section: A (2016) 52: 55 and our study has been selected for the cover of the March 2016 issue. In the framework of NEDA, besides the simulations, I have been actively participating to the tests, which aimed to characterize the prototypes and their functionality with digital sampling electronics. The preparation and the outcomes of these tests are also discussed in Chapter 4. The second part is devoted to the analysis of two experiments. Hence, the nuclear instrumentation, like HPGe arrays (AGATA and EXOGAM), liquid scintillator based neutron detector array (the Neutron Wall) and CsI scintillator based light-particle detector array (DIAMANT) used in the experiments have been described in Chapter 5. The first experiment has been done at GANIL with EXOGAM - Neutron Wall - DIAMANT setup using fusion-evaporation reaction S-32 + Si-28. The analysis of this experiment provided experience on the data analysis of an experiment where the Neutron Wall involved, which the NEDA detectors will replace. The preparation, analysis and the results of this experiment are discussed in Chapter 6. The second experimental activity has been done at GSI - Fragment Separator Facility (FRS) using the AGATA - PreSPEC setup to investigate the collectivity in the isomeric state 12+. The unstable Fe-52 beam at relativistic energies with an isomeric ratio of 14(2)% underwent Coulomb excitation by heavy Au-197 target. The reaction cross sections have been calculated prior to the experiment using the code DWEIKO, using Global Optical Potentials calculated by T. Furumoto. A comparison has been done between the calculated and measured cross sections of 0+ → 2(1)+ and 0+ → 2(2)+ excitations. The reduced matrix element of the candidate for the 12+ → 14+ has been measured experimentally and compared with the LSSM calculations, suggesting a larger degree of collectivity in the involved states. The detector setup, analysis and results of this experiment are discussed in Chapter 7.