Michelle Hui, Daniel Kocevski, and Joshua Wood (ST12) proposed to investigate wide-field gamma-ray detector technology to the TIP program and was selected for funding in FY22. The project involves characterizing a phoswich detector that couples CeBr3 and NaI(Tl) crystals and comparing it to the flight heritage design of NaI(Tl) and CsI(Na). The novel material CeBr3 has faster timing properties that can lower energy threshold and detector deadtime, and the phoswich dual-crystal configuration provides better viewing angle sensitivity compared to the traditional single-crystal detector. These are critical factors for a wide field all-sky gamma-ray monitor which is identified as one of the required capabilities for multi-messenger and time domain astronomy by the Astro2020 Decadal Survey.