The U.S. Department of Energy Office of Science has approved the project baseline (Critical Decision 2, the integrated scope, cost, and schedule) and the start of construction (Critical Decision 3) for the Gamma-Ray Energy Tracking Array (GRETA) project, a new high-resolution gamma-ray detector system that will be used at FRIB.

Science it will enable

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 (Berkeley Lab) has had a leadership role in the creation of GRETINA and now 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.

After completion, GRETA will come to FRIB and will be offered at a future PAC after it is operational. It will be offered for experiments at ReA and the S800. For experiments at the S800, it will use the modified GRETINA frame allowing for more than 20 GRETA quads.

Collaborations

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.