In preparation for the AGATA campaign at GSI, a set of simulation tools to be utilised with the AGATA simulation code has been developed, enabling the response of the proposed AGATA geometries for use at GSI to be simulated following a relativistic Coulomb excitation reaction. The γ-ray tracking algorithms, crucial to the performance of AGATA, have previously been untested in a relativistic environment with high levels of background, and as a result has been evaluated in a variety of simulated conditions with varying levels of background.
To assess the performance of the γ-ray tracking algorithms, the γ-ray spectra of the RISING array from a recent PreSPEC experiment (Experiment S377 in May 2011) has been compared with a simulation, in order to determine the simulation input that provided a similar spectral response. The optimum simulation input was then used to evaluate the performance of the AGATA geometries and the γ-ray tracking under the same conditions.
Simulations have highlighted that tracking is possible for unshielded detectors in the experimental conditions at GSI, providing that the atomic background multiplicity can be kept below a certain threshold. The inclusion of the extreme levels of atomic background in the simulations completely saturates the γ-rays of interest, suggesting that the use of shielding needs to be further investigated. Assuming that shielding or analysis techniques are to be used experimentally, the atomic back- ground was removed from the simulations leaving only the high energy background component, and the consecutive performance of the AGATA geometries were investigated and compared with RISING. Under such conditions, the AGATA geometries gave up to a factor of ∼2 improvement in terms of the peak-to-total ratio compared to the RISING array.
