Agata: in-beam spectroscopy with relativistic beams

An analysis of the capabilities of AGATA for in-beam $\gamma$-ray spectroscopy at relativistic energies is presented. AGATA's ability to determine the position of $\gamma$-ray interaction points in the Germanium crystal provides the crucial ingredient for attaining high $\gamma$-ray energy resolution when the emitting nucleus is traveling at more than half the speed of light. This is the typical velocity of exotic nuclei exiting the SuperFRS spectrometer at the future FAIR facility, where AGATA will be deployed as part of the high-resolution in-beam spectroscopy project, HISPEC. A discussion of different experimental techniques using AGATA under these conditions is presented, including analysis of the different Doppler-based methods for lifetime determination. The properties of the key reaction mechanisms expected to be applied for in-beam $\gamma$-ray spectroscopy at FAIR are discussed, along with the aspects of those reactions that can be exploited by the advanced capabilities of the AGATA array.