This thesis is divided into two parts: the investigation of low-energy electric dipole response (LEDR) in atomic nuclei and the development of a digital data acquisition system for nuclear-structure experiments. The first part focuses on uncovering the nuclear-structure features influencing the LEDR of 120Sn below the neutron-separation threshold through two complementary experiments and theoretical analysis. The 120Sn(a, a'g) and 119Sn(d, pg) experiments are detailed, alongside nuclear-structure calculations using the Quasiparticle-Phonon-Model (QPM) and two reaction-theory approaches. Findings from the (a, a'g) experiment suggest the existence of isoscalar excitations with a surface-mode character in the LEDR, akin to neutron-skin oscillation. The 119Sn(d, pg) transfer experiment serves as a novel method to explore the microscopic nature of individual LEDR states. The strong correlation between theoretical (d, pg) cross sections and experimental data validates the QPM and Energy-Density-Functional calculations. Consistent comparisons between theory and experiment reveal significant agreement on several accessible values. This microscopic information enhances the understanding of nuclear-structure phenomena in the LEDR of 120Sn. The second part discusses the design and commissioning of an advanced digital data acquisition system, which features reduced dead time and exceptional energy resolution for gamma-ray spectroscopy.
