GRETA, a new high-resolution gamma-ray detector system that will be used at FRIB, has achieved Critical Decision-3a (CD-3a) approval by the U.S. Department of Energy Office of Science. CD-3a approves the start of civil construction and long-lead procurements.

The Gamma-Ray Tracking Array (GRETA) is designed to reveal new details about the structure and inner workings of atomic nuclei, and to elevate our understanding of matter and the stellar creation of elements. GRETA will be combined with the existing detector array – the Gamma-Ray Energy Tracking In-beam Nuclear Array (GRETINA) – to create a full spherical array. Lawrence Berkeley National Laboratory (LBNL) has had a leadership role in the creation of GRETINA and now GRETA.

A collaboration of scientists from Lawrence Berkeley National Laboratory, Argonne National Laboratory, MSU, Oak Ridge National Laboratory, and Washington University designed and constructed GRETINA. GRETINA was the first stage of GRETA.

The GRETA detector array will incorporate 12 GRETINA detector modules. The GRETA detector array is designed to surround samples, forming a spherical shell to more completely and precisely measure the energy and 3D position of gamma rays propagating in the detectors. Gamma rays are highly penetrating, highly energetic forms of light that are emitted from excited nuclear states.

“We thank the DOE-SC Office of Nuclear Physics for its continued support and are thrilled about LBNL’s progress in delivering GRETA -- both will ensure the full scientific capability of FRIB as envisioned in the 2015 Long Range Plan for Nuclear Science,” said Thomas Glasmacher, FRIB Project director.

For more information, see the article on the LBNL website.