Universität zu Köln

Rosiak, David Pawel (2018). Coulomb excitation of doubly-magic 132Sn at HIE-ISOLDE and development of escape-suppression shields for the MINIBALL spectrometer. PhD thesis, Universität zu Köln.

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Abstract

Collective properties of the exotic doubly-magic nucleus 132Sn, 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 132Sn beam was post accelerated up to 5.5~MeV/u and guided onto a 3.1~mg/cm^2 thick 206Pb 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 132Sn. The final reduced transition strengths are B(E2 \uparrow ; 0^+_g.s. \rightarrow 2^+_1 ) = 0.0869 +- 0.019 e^2b^2, B(E3 \uparrow ; 0^+_g.s. \rightarrow 3^-_1 ) = 0.11 +- 0.035 e^2b^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 60Co 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\%.

Item Type:	Thesis (PhD thesis)
Creators:	Creators Email ORCID ORCID Put Code Rosiak, David Pawel drosiak@ikp.uni-koeln.de UNSPECIFIED UNSPECIFIED
URN:	urn:nbn:de:hbz:38-84694
Date:	28 May 2018
Language:	English
Faculty:	Faculty of Mathematics and Natural Sciences
Divisions:	Faculty of Mathematics and Natural Sciences > Department of Physics > Institute for Nuclear Physics
Subjects:	Physics
Uncontrolled Keywords:	Keywords Language Coulomb excitation nuclear structure gamma-ray spectroscopy doubly-magic 132Sn MINIBALL Compton suppression UNSPECIFIED
Date of oral exam:	16 July 2018
Referee:	Name Academic Title Reiter, Peter Prof. Dr. Jolie, Jan Prof. Dr.
Refereed:	Yes
URI:	http://kups.ub.uni-koeln.de/id/eprint/8469