In this work we endeavor to engineer a new tool for isotope-specific assay and detection. We propose to utilize Nuclear Resonance Fluorescence (NRF) as the process that gives isotope-specific information about the object under investigation. Careful experimental and theoretical studies of angular dependencies of signal (NRF) and noise (other significant scattering channels) are presented. These studies motivate engineering design of detector array exploiting signal vs. noise discrepancies in angular distributions. User-defined materials of interest, detection / assay times and accuracy requirements inform the design yielding optimal performance.