In-beam experiment with the γ-ray tracking detector MARS

Abstract

The lineshapes and peak position of Doppler corrected gÀray spectra from in-beam experiments at relativistic energies are investigated with respect to the intrinsic energy resolution of the employed detectors, the particles' velocities, and the photons' emission angle uncertainties at the moment of gÀray emission. The uncertainties in velocity and photon emission angle are dependent on the lifetime of the excited state. The impact of these two observables on the lineshape and energy resolution are studied for the RISING gÀspectrometer by means of simulations and experimental results from a twostep fragmentation experiment at % 200 MeV=u. Potential use of the distinct lineshape for lifetime determination is demonstrated for measured gÀray transitions.