Gamma-ray tracking detectors: physics opportunities and status of GRETINA

Gamma-ray tracking detectors using highly segmented germanium detectors will give higher efficiency, better peak-to-total ratio and much higher position resolution than current generation of detectors. Particularly, the capability of reconstructing the position of the interaction with millimeters resolution is needed to fully exploit the physics opportunities provided by the next generation radioactive beam facilities. This paper presents the basic concepts of tracking, examples of physics opportunities, and the status of the project GRETA/GRETINA.