The field of experimental nuclear physics has been pushing further and further away from the valley of stability on the chart of nuclides, investigating exotic systems in order to test our understanding of nuclear structure, nuclear reactions, and nuclear astrophysics. In particular, halo nuclei, which have extended matter distributions and where large break-up and transfer cross sections are observed close to the Coulomb barrier, provide a unique opportunity to probe the dynamics of the fusion process in the energy region around the barrier. Halo nuclei are notoriously hard to produce as beams. In addition, as we move away from stability, the rates of exotic beams decrease dramatically and it becomes a very time-consuming process to change and tune beam energies in order to measure several points of a reaction excitation function. New detector developments are needed to reliably maximize the efficiency of measurements with exotic beams. Active target detectors --- detectors where the target material is also the detection medium --- have been developed around the world, allowing for measurements of a large range of the reaction excitation function without changing the beam energy and providing a large angular coverage, thus maximizing the efficiency of the detection process. At Florida State University, I developed the self-normalizing, highly efficient, versatile, and portable Encore active target detector. This work describes the design, construction, and characterization of the Encore active target detector, as well as the physics results obtained with the device. I describe a measurement of the ^17F + ^12C fusion excitation function performed in search for effects of the loosely-bound or halo nature of this nucleus. A beam of the weakly-bound ^17F nucleus (S[subscript p] = 600 keV), with an excited proton-halo state (bounded by 100 keV), was made at the RESOLUT facility at the John D. Fox accelerator and was used to provide insight on the effects of proton halo-nuclei in the fusion process. Moreover, I present a surprising result in the mirror ^17O + ^12C system, which showed unexpected oscillatory behavior that has previously only been observed in light symmetric systems. Furthermore, this dissertation exhibits the versatility of the Encore detector by presenting proof-of-principle experiments that show its ability to measure ɑ-induced reactions and fusion-induced fission reactions, both of which are important for understanding astrophysical processes.
