Overview

Led by Lawrence Berkeley National Laboratory (LBNL), the development and construction of the Gamma-Ray Energy Tracking Array (GRETA) was completed in summer 2025. GRETA was delivered to FRIB and is now available as a FRIB-supported Instrument for high-resolution gamma-ray spectroscopy. GRETA will provide new insights into the nature of the nuclear force and will help decipher how the properties of rare isotopes connect to the fingerprints of element and isotope production in the universe. 

Technical Details

GRETA is a novel instrument for studying the properties of atomic nuclei through the precise measurement of γ rays that reveal the energies of properties of excited quantum states of nuclei. Optimized to reconstruct the energy and 3D position of γ-ray interactions within the germanium crystals, GRETA’s design innovates through the combination of full solid-angle coverage with high detection efficiency, excellent energy and position resolution, and background rejection capability through γ-ray tracking, to majorly contribute to a large fraction of the nuclear structure and nuclear astrophysics programs at FRIB.