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 $\mathitΔE$-$E$ 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.