Speaker
Description
High-purity germanium (HPGe) detectors have long been at the heart of powerful γ-ray spectrometers dedicated to unraveling the complex structure of the atomic nucleus. Recent advances in detector technology, data acquisition, and digital signal processing have refined γ-ray detection techniques, enabling the extraction of precise position information from the pulse shapes of semiconductor detectors.
Electrical segmentation of HPGe crystals improves angular granularity and position sensitivity while allowing the reconstruction of individual γ-ray interaction points through the analysis of signals induced in neighboring segments. These technological developments have led to the construction of new-generation γ-ray tracking arrays—such as GRETINA/GRETA in the U.S. and AGATA in Europe— which are now being employed at major facilities worldwide to exploit their full experimental potential.
In 2024–2025, the fourth and final GRETINA campaign took place at Argonne National Laboratory. During this period, GRETINA was coupled to three complementary setups: the Fragment Mass Analyzer (FMA) for fusion-evaporation studies of exotic nuclei, the Oak Ridge Rutgers University Barrel Array (ORRUBA) for direct-reaction measurements, and the Compact Heavy Ion COunter (CHICO-X) for Coulomb-excitation experiments. This one-year campaign comprised 29 experiments, making it the most extensive and
demanding series ever conducted at ATLAS. In October 2025, GRETINA was transferred back to FRIB to begin its upgrade into GRETA.
In this presentation, I will report on the fourth GRETINA experimental campaign at ATLAS, highlighting key examples of the physics investigated, and will outline the ongoing upgrade toward GRETA and its prospective future deployment at ATLAS.
This research was partially supported by the U.S. Department of Energy, Office of Science, Office of Nuclear Physics, under contract number DE-AC02-06CH11357. This study used resources of ANL’s ATLAS facility, which is a DOE Office of Science User Facility.