Coulomb excitation of doubly-magic $^{132}$ Sn at HIE-ISOLDE and development of escape-suppression shields for the MINIBALL spectrometer

Collective properties of the exotic doubly-magic nucleus $^{132}$Sn, in particular the first excited 2$^{+}$ and 3$^{-}$ states, were investigated via safe Coulomb excitation. The experiment was performed in October 2016 at the HIE-ISOLDE facility at CERN. The challenging Coulomb excitation was realized utilizing the new commissioned stage 1 HIE-ISOLDE accelerator in combination with the high resolution and high efficient MINIBALL array. The radioactive $^{132}$Sn beam was post accelerated up to 5.5~MeV/u and guided onto a 3.1~mg/cm$^{2}$ thick $^{206}$Pb target. Projectile and target deexcitation were recorded in coincidence with the scattered nuclei to reduce the amount of background radiation in the $\gamma$-ray spectra and to perform the Doppler correction. B(E2), B(E3) and B(E1) values were determined for the corresponding transitions 0$^{+}$$_{g.s.}$ $\rightarrow$ 2$^{+}$$_{1}$, 0$^{+}$$_{g.s.}$ $\rightarrow$ 3$^{-}$$_{1}$, and 2$^{+}$$_{1}$ $\rightarrow$ 3$^{-}$$_{1}$ of $^{132}$Sn. The final reduced transition strengths are B(E2 $\uparrow$ ; 0$^{+}$$_{g.s.}$ $\rightarrow$ 2$^{+}$$_{1}$ ) = 0.0869 +- 0.019 e$^{2}$b$^{2}$, B(E3 $\uparrow$ ; 0$^{+}$$_{g.s.}$ $\rightarrow$ 3$^{-}$$_{1}$ ) = 0.11 +- 0.035 e$^{2}$b$^{3}$ and B(E1 $\uparrow$ ; 2$^{+}$$_{1}$ $\rightarrow$ 3$^{-}$$_{1}$) = (9.05 +- 3.04) x 10^{-6} e^2b. These experimental results were compared to state-of-the-art large-scale shell-model calculations, a relativistic random phase approximation and a random phase approximation calculation. The second part of the present thesis deals with the manufacturing process and the first performance tests of the prototype escape-suppression-shield detector for the MINIBALL spectrometer. Measurements were performed with a stand-alone escape-suppression detector and with the assembled system in combination with a MINIBALL triple cluster. The performance of the combined system was quantified via the peak-to-total ratio of measured $^{60}$Co gamma-ray spectra. A comparison between the achieved results of the prototype detection system and prior performed Geant4 simulations is presented. The achieved peak-to-total value of 41% with source measurements of the prototype detector is in good agreement with the predicted value of 44\%.