The gamma ray tracking technique uses highly segmented Ge detectors, and obtains pulse shape information from each of the segments using fast digital electronics. These pulses are analyzed to determine the energy, time, and three-dimensional positions of all gamma-ray interactions. This information is then used, together with the characteristics of Compton scattering and pair-production processes, to track the scattering sequences of the gamma rays. A 4π tracking array will give higher efficiency, better peak-to-total ratio and much higher position resolution, and thus increase the detection sensitivity by factors of several hundred compared to current arrays used in nuclear physics research.

A first implementation of such an array, GRETINA, is being constructed by a US collaboration, using coaxial crystals, and is expected to be completed in 2011. It will cover 1/4 of the 4π solid angle using seven 4-crystal detector modules. After engineering and commission runs at the 88-Inch Cyclotron in LBNL, it will then move to NSCL MSU, ATLAS ANL and HRIBF ORNL for experiments taking advantage of the unique capabilities available at these facilities. It will provide world leading opportunities to advance studies in nuclear structure, nuclear reactions, and fundamental symmetries.

In this talk, I will discuss the principle, current status, and science opportunities of GRETINA.

Argonne Physics Division Colloquium Schedule