Combining γ-ray and particle spectroscopy with SONIC@HORUS

Abstract The particle spectrometer SONIC for particle- γ coincidence measurements was commissioned at the Institute for Nuclear Physics in Cologne, Germany. SONIC consists of up to 12 silicon Δ E - E telescopes with a total solid angle coverage of 9%, and will complement HORUS, a γ -ray spectrometer with 14 HPGe detectors. The combined setup SONIC@HORUS is used to investigate the γ -decay behaviour of low-spin states up to the neutron separation threshold excited by light-ion inelastic scattering and transfer reactions using beams provided by a 10  MV FN Tandem accelerator. The particle- γ coincidence method will be presented using data from a 92 Mo(p,p’ γ ) experiment. In a 119 Sn(d,X) experiment, excellent particle identification has been achieved because of the good energy resolution of the silicon detectors of approximately 20  keV. Due to the non-negligible momentum transfer in the reaction, a Doppler correction of the detected γ -ray energy has to be performed, using the additional information from measuring the ejectile energy and direction. The high sensitivity of the setup is demonstrated by the results from a 94 Mo(p,p’ γ ) experiment, where small γ -decay branching ratios have been deduced.