The quadrupole moment of176Lu

The intrinsic quadrupole moment of¹⁷⁶Lu has been determined by Coulomb excitation with α-particles to be 6.98±0.10 b. Evidence for a new level at approximately 578 keV with presumably collective structure is presented.     

Structure of neutron-rich nuclei around the N = 126 closed shell; the yrast structure of 205Au126 up to spin-parity I^{\pi} = (19/2+)

Heavy neutron-rich nuclei have been populated through the relativistic fragmentation of a $\ensuremath ^{208}_{\ 82}{\rm Pb}$ beam at $\ensuremath E/A = 1$ GeV on a $\ensuremath 2.5 {\rm g/cm^2}$ thick Be target. The synthesised nuclei were selected and identified in-flight using the fragment separator at GSI. Approximately 300 ns after production, the selected nuclei were implanted in an $\ensuremath \sim 8$ mm thick perspex stopper, positioned at the centre of the RISING $\ensuremath \gamma$ -ray detector spectrometer array. A previously unreported isomer with a half-life $\ensuremath T_{1/2} = 163(5)$ ns has been observed in the N = 126 closed-shell nucleus $\ensuremath ^{205}_{\ 79}{\rm Au}$ . Through $ \gamma$ -ray singles and $ \gamma$ - $ \gamma$ coincidence analysis a level scheme was established. The comparison with a shell model calculation tentatively identifies the spin-parity of the excited states, including the isomer itself, which is found to be $\ensuremath I^{\pi} = (19/2^+)$ .     

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Spectroscopy and reaction mechanism of the system90Zr→232Th in the vicinity of the Coulomb barrier

A study of few nucleon transfer reactions in conjunction with Coulomb excitation was performed by bombarding a²³²Th target with⁹⁰Zr projectiles at incident energies close to the Coulomb barrier. Particle-γ coincidence techniques using the Heidelberg-Darmstadt Crystal Ball were employed to select excited states of reaction products. Around the grazing angle roughly 2/3 of the total cross section goes into transfer channels, half of it formed by 1n...4n transfer. The enhancement of the 2n cross section is in accord with a sequential process with a highly excited intermediate state. A correlated pair transfer directly populating yrast states appears to be negligibly small. The excitation energy is almost equally distributed upon the outgoing reaction partners for the 1n channel and there are indications for a similar behaviour of the 2n channel.     

Magnetic moments,E3 transitions and the structure of high-spin core excited states in 211Rn

The results of g-factor measurements of high-spin states in ²¹¹Rn are: $\text{E}{}_{\mathrm{<mtext>x</mtext>}}\text{= 8856 + Δ′}\text{keV}\text{(J}{}^{\mathrm{\pi }}\text{=}\text{63}\text{2}{}^{\mathrm{?}}\text{)}$, g = 0.626(7); $\text{6101 + Δ′}\text{KeV}\text{(}\text{49}\text{2}{}^{\mathrm{+}}\text{), 0.766(8)}$; $\text{5347 + Δ′}\text{KeV}\text{(}\text{43}\text{2}{}^{\mathrm{?}}\text{), 0.74(2)}$; $\text{3927 + Δ}\text{KeV}\text{(}\text{35}\text{2}{}^{\mathrm{+}}\text{), 1.017(12)}$; $\text{1578 + Δ}\text{KeV}\text{(}\text{17}\text{2}{}^{\mathrm{?}}\text{), 0.912(9)}$. These results together with measured E3 transition strengths and shell model calculations are used to assign configurations to the core excited states in ²¹¹Rn. Mixed configurations are required to explain the g-factors and enhanced E3 strengths simultaneously.     

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Short-lived isomers in 211Rn and 210Rn

The following mean lives of excited states in ²¹¹Rn and ²¹⁰Rn have been measured: ²¹¹Rn: 8169 + Δ' keV, (τ = 3.3(3) ns), 7400 + Δ' keV (2,1(5) ns), 6101 + Δ' (41(2) ns), 5247 + Δ keV (5(2) ns), 3244 + Δ keV (3.9(8) ns), 2651 + Δ keV (9.6(4) ns); ²¹⁰Rn: 8555 + Δ keV (2.6(3) ns), 4994 + Δ keV (19(1) ns), 1665 keV (15.0(15) ns). Some theoretical implications of these measurements for the structure of ²¹¹Rn and ²¹⁰Rn are discussed.     

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High spin states in 210Pb

High spin states in nuclei in the ²⁰⁸Pb region were populated in deep inelastic collisions of ¹³⁶Xe and ²⁰⁸Pb projectiles with thick ²⁰⁸Pb targets at about 50 MeV above the Coulomb barrier. Prompt and prompt-delayed γ-ray coincidences were measured. Four new states above the 8⁺ isomer in ²¹⁰Pb were found and spins and parities assigned from theoretical expectations. The results are discussed in the frame of shell model theory.