Combining {\gamma}-ray and particle spectroscopy with SONIC@HORUS

TL;DR

The paper describes the development and commissioning of the SONIC particle spectrometer combined with the HORUS gamma-ray spectrometer, enabling detailed particle-$\gamma$ coincidence measurements to study nuclear decay behaviors with high sensitivity.

Contribution

It introduces the combined SONIC@HORUS setup, demonstrating its capability for high-resolution particle identification and gamma-ray detection in nuclear physics experiments.

Findings

Excellent particle identification with ~20 keV resolution.

Successful Doppler correction using ejectile data.

Detection of small gamma-decay branching ratios.

Abstract

The particle spectrometer SONIC for particle-$\gamma$ coincidence measurements was commissioned at the Institute for Nuclear Physics in Cologne, Germany. SONIC consists of up to 12 silicon $\mathit{\Delta}E$-$E$ telescopes with a total solid angle coverage of 9%, and will complement HORUS, a $\gamma$-ray spectrometer with 14 HPGe detectors. The combined setup SONIC@HORUS is used to investigate the $\gamma$-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-$\gamma$ coincidence method will be presented using data from a $^{92}$Mo(p,p'$\gamma$) 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 $\gamma$-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'$\gamma$) experiment, where small $\gamma$-decay branching ratios have been deduced.