In-beam Study of Extremely Neutron deficient Nuclei Using the Recoil-Decay Tagging Technique

The low-lying structures of the extremely neutron-deficient nuclei 106Te, 107Te, 110Xe, 170Ir and 172Au have been investigated experimentally. Prompt gamma rays emitted in fusion-evaporation reactions were detected by the Jurogam HPGe array. The gamma rays were assigned to specific reaction channels using the recoil-decay tagging technique provided by the gas-filled separator RITU and the GREAT focal-plane spectrometer. The experimental set-up and the technique used to extract the information from the experimental data are described in detail. Results were interpreted in terms of the nuclear shell model and Total Routhian Surface calculations. In addition, decay studies on 170Ir, 172Au and 164Re led to the discovery of new alpha-decay branches in these nuclei.QC 2010073

In-beam study of 106Te and 107Te using the recoil decay tagging technique

Atomic nuclei are complex many-body systems and exhibit an interplay between single-particle and collective degrees of freedom. In order to describe and predict the “behavior” of nucleons inside the nuclei a variety of theoretical models have been created, each applicable to their own domain of nuclear phenomena. Experimental information is needed in order to test and improve the various theoretical models with the ultimate goal of creating unified theory of nuclear structure. In-beam γ-ray spectroscopy is one way of probing the inner structure of nuclei and it is the subject of this thesis, which describes the first identification of excited states in the extremely neutron deficient nuclei 106Te and 107Te. The experiments were performed at the Accelerator Laboratory of the University of Jyväskylä, Finland, using the recoil-decay tagging technique. Prompt γ rays emitted following fusion evaporation reactions were detected by the Jurogam detector array and the selection of the γ rays of interest was based on the recoil identification provided by the RITU gas-filled recoil separator and the GREAT focal plane spectrometer. The production cross sections were estimated to be 25nb and 1μb for 106Te and 107Te, respectively. In case of the nucleus 106Te, several γ rays have been observed. A vibrational-like yrast band has been suggested. For 107Te a number of γ rays have been assigned and a tentative partial level scheme has been suggested. The experimental data have been compared to shell model calculations.QC 2010111

In-beam study of 106Te and 107Te using the recoil decay tagging technique

Atomic nuclei are complex many-body systems and exhibit an interplay between single-particle and collective degrees of freedom. In order to describe and predict the “behavior” of nucleons inside the nuclei a variety of theoretical models have been created, each applicable to their own domain of nuclear phenomena. Experimental information is needed in order to test and improve the various theoretical models with the ultimate goal of creating unified theory of nuclear structure. In-beam γ-ray spectroscopy is one way of probing the inner structure of nuclei and it is the subject of this thesis, which describes the first identification of excited states in the extremely neutron deficient nuclei 106Te and 107Te. The experiments were performed at the Accelerator Laboratory of the University of Jyväskylä, Finland, using the recoil-decay tagging technique. Prompt γ rays emitted following fusion evaporation reactions were detected by the Jurogam detector array and the selection of the γ rays of interest was based on the recoil identification provided by the RITU gas-filled recoil separator and the GREAT focal plane spectrometer. The production cross sections were estimated to be 25nb and 1μb for 106Te and 107Te, respectively. In case of the nucleus 106Te, several γ rays have been observed. A vibrational-like yrast band has been suggested. For 107Te a number of γ rays have been assigned and a tentative partial level scheme has been suggested. The experimental data have been compared to shell model calculations.QC 2010111

Prompt and delayed spectroscopy of 199At

The neutron-deficient nucleus At199 has been studied through γ-ray and electron spectroscopy, using the recoil-decay tagging technique. Two experiments were conducted, using a gas-filled recoil separator with a focal-plane spectrometer alone and together with a germanium-detector array at the target position. The resulting level scheme for At199 includes a new isomer with a half-life of 0.80(5) μs and a spin and parity of (29/2+). The 13/2+ isomer, which de-excites via an M2 transition to the 9/2− ground state, was measured to have a half-life of 70(20) ns. Our earlier version of the level scheme for At197 has been updated as well.peerReviewe

Low-lying excited states in the neutron-deficient isotopes 163Os and 165Os

Excited states in the neutron-deficient isotopes 163Os and 165Os were identified using the JUROGAM and GREAT spectrometers in conjunction with the RITU gas-filled separator. The 163Os and 165Os nuclei were populated via the 106Cd(60Ni,3n) and 92Mo(78Kr,2p3n) reactions at bombarding energies of 270 MeV and 357 MeV, respectively. Gamma-ray emissions from these nuclei have been established unambiguously using the recoil-decay tagging technique and a coincidence analysis has allowed level schemes to be established. These results suggest that the yrast states are based upon negative-parity configurations originating from the νf7/2 and νh9/2 orbitals.peerReviewe