This key instrument for FRIB builds directly on the success of GRETINA, which has been taking physics data since 2012. GRETA is funded by the DOE Office of Science, Office of Nuclear Physics and the project is led by LBNL with contributions from ANL, NSCL and ORNL.

Following the DOE CD3A approval for the GRETA Project, a contract with Mirion Technologies was signed to procure eight Quad Modules (QM), each containing four germanium crystals. The full scope is for 18 new QM that together with 12 from GRETINA to complete the 30 QM required to cover the 4π geometry. At the end of July, team members from LBNL and MSU visited the company’s Lingolsheim (France) facilities to do the Factory Acceptance Test of the first Quad (Q14). Shortly thereafter the detector was shipped to Berkeley where mechanical measurements with a coordinate measuring machine (CMM) were performed to confirm the dimensions of the end-cap, critical to the close packing 4π geometry of the array (Figure 1).

Figure 2. Prototype of the GRETA digitizer electronics.

Once a preliminary analysis confirmed that Q14 met the mechanical specifications, it was shipped to NSCL/MSU for further performance tests and was accepted in early November, marking an important milestone for the Detector Systems and the Project. Mirion continues to make progress with the next two modules. The acceptance tests for Q15 carried out earlier this month showed an excellent performance and will be delivered to the Project just before the Holidays, while Q16 is still on track for delivery by the end of March 2020.

Another important project milestone has been achieved as part of the End-to-End tests. These tests confirmed that prototypes of the digitizers, shown in Figure 1. (right), and filter boards meet comfortably our physics requirements and the data transfer from the detector to the computer is working as planned. The Electronics, Computers, and Mechanical systems designs are in their final stages and Final Design Reviews are being scheduled for February. These and also a comprehensive plan for System Assembly has been developed in preparation for the DOE CD2/3 review that will take place at the end of April.