Change in structure between the I = 1/2 states in 181Tl and 177,179Au

The first accurate measurements of the α-decay branching ratio and half-life of the Iπ=1/2+ ground state in 181Tl have been made, along with the first determination of the magnetic moments and I=1/2 spin assignments of the ground states in 177,179Au. The results are discussed within the complementary systematics of the reduced α-decay widths and nuclear g factors of low-lying, Iπ=1/2+ states in the neutron-deficient lead region. The findings shed light on the unexpected hindrance of the 1/2+→1/2+, 181Tl→g177Aug α decay, which is explained by a mixing of π3s1/2 and π2d3/2 configurations in 177Aug, whilst 181Tlg remains a near-pure π3s1/2. This conclusion is inferred from the g factor of 177Aug which has an intermediate value between those of π3s1/2 and π2d3/2 states. A similar mixed configuration is proposed for the Iπ=1/2+ ground state of 179Au. This mixing may provide evidence for triaxial shapes in the ground states in these nuclei

In-source laser spectroscopy of Cu-75,Cu-77,Cu-78: Direct evidence for a change in the quasiparticle energy sequence in Cu-75,Cu-77 and an absence of longer-lived isomers in Cu-78

This paper describes measurements on the isotopes 75,77,78Cu by the technique of in-source laser spectroscopy, at the ISOLDE facility, CERN. The role of this technique is briefly discussed in the context of this and other, higher resolution, methods applied to copper isotopes in the range 57-78Cu. The data, analyzed in comparison with previous results on the lighter isotopes 59,63Cu, establish the ground-state nuclear spin of 75,77Cu as 5/2 and yield their magnetic dipole moments as +1.01(5)μN and +1.61(5)μN, respectively. The results on 78Cu show no evidence for long-lived isomerism at this mass number and are consistent with a spin in the range 3-6 and moment of 0.0(4) μN. ©2011 American Physical Society

In-source laser spectroscopy of 75,77,78Cu: Direct evidence for a change in the quasiparticle energy sequence in 75,77Cu and an absence of longer-lived isomers in 78Cu

This paper describes measurements on the isotopes 75,77,78Cu by the technique of in-source laser spectroscopy, at the ISOLDE facility, CERN. The role of this technique is briefly discussed in the context of this and other, higher resolution, methods applied to copper isotopes in the range 57−78Cu. The data, analyzed in comparison with previous results on the lighter isotopes 59,63Cu, establish the ground-state nuclear spin of 75,77Cu as 5/2 and yield their magnetic dipole moments as +1.01(5)μN and +1.61(5)μN, respectively. The results on 78Cu show no evidence for long-lived isomerism at this mass number and are consistent with a spin in the range 3–6 and moment of 0.0(4) μN.status: publishe

α-decay study of 182;184Tl

α-decay spectroscopy of 182,184Tl has been performed at the CERN isotope separator on-line (ISOLDE) facility. New fine-structure α decays have been observed for both isotopes. α-decay branching ratios of 0.089(19)%, 0.047 (6)% and 1.22(30)% have been deduced for the (10−), (7+) and (2−) states respectively in 184Tl and a lower limit of 0.49% for the α-decay branching ratio of 182Tl. A new half-life of 9.5(2) s for the (2−) state in 184Tl and 1.9(1) s for the low-spin state in 182Tl has been deduced. Using α–γ coincidence analysis, multiple γ rays were observed de-exciting levels in 178,180Au fed by 182,184Tl α decays. The γ transitions connecting these low-lying states in 178,180Au are essential to sort the data and possibly identify bands from in- beam studies in these isotopes. Owing to the complex fine-structure α decays and limited knowledge about the structure of the daughter nuclei, only partial level schemes could be constructed for both gold isotopes in the present work. Reduced α-decay widths have been calculated and are compared with values obtained in neighboring odd-A and even-A thallium isotopes. Except for the allowed α decay of the 184Tl (10−) state, the other fine-structure α decays observed in this study are hindered. This points to strong structural changes between parent thallium and daughter gold isotopes.journal_title: Journal of Physics G: Nuclear and Particle Physics article_type: paper article_title: -decay study of ${}^{\mathrm{182,184}}$Tl copyright_information: © 2016 IOP Publishing Ltd date_received: 2015-09-11 date_accepted: 2015-11-06 date_epub: 2016-01-08status: publishe

Charge radii of odd-A 191–211Po isotopes

Isotope shifts have been measured for the odd-A polonium isotopes 191–211Po and changes in the nuclear mean square charge radii δr2 have been deduced. The measurements were performed at CERN-ISOLDE using the in-source resonance-ionization spectroscopy technique. The combined analysis of these data and our recent results for even-A polonium isotopes indicates an onset of deformation already at 197,198Po, when going away from stability. This is significantly earlier than was suggested by previous theoretical and experimental studies of the polonium isotopes. Moreover and in contrast to the mercury isotopes, where a strong odd–even staggering of the charge radii of the ground states was observed by approaching the neutron mid-shell at N = 104, no such effect is present in polonium down to 191Po. Consequently the charge radii of both isomeric and ground states of the odd-A polonium isotopes follow the same trend as the even-A isotopes.status: publishe

alpha-decay branching ratio of Pt-180

A study of the $^{180}\mathrm{Hg}$ decay chain performed at the CERN-ISOLDE facility has allowed the ground-state–to–ground-state α decay of $^{180}\mathrm{Pt}$ to be investigated. A more precise α-decay branching ratio of $b_{\alpha}$ $(^{180}\mathrm{Pt})=0.52(5)$% has been deduced. The reduced α-decay width calculated using the new value provides a more consistent picture of the systematics for $J^\pi=0^+\rightarrow 0^+$ ground-state–to–ground-state state α decays of neutron-deficient, even-even platinum isotopes

α-decay branching ratio of 180Pt

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Early onset of deformation in the neutron-decient polonium isotopes

In-source laser spectroscopy has been performed at CERN-ISOLDE with the RILIS laser ion source on 191-204, 206,208-211, 216, 218Po. New information on the B decay of 199Po were extracted in the process, challenging previous results. Large-scale atomic calculations were performed to extract the changes in the mean-square charge radius d(r2) from the isotope shifts. The d(r2) for the even-A isotopes reveal a large deviation from the spherical droplet model for N < 116.status: publishe

Radium ionization scheme development: The first observed autoionizing states and optical pumping effects in the hot cavity environment

© 2018 The Authors This paper reports on resonance ionization scheme development for the production of exotic radium ion beams with the Resonance Ionization Laser Ion Source (RILIS) of the CERN-ISOLDE radioactive ion beam facility. During the study, autoionizing states of atomic radium were observed for the first time. Three ionization schemes were identified, originating from the 7s2 1S0 atomic ground state. The optimal of the identified ionization schemes involves five atomic transitions, four of which are induced by three resonantly tuned lasers. This is the first hot cavity RILIS ionization scheme to employ optical pumping effects. The details of the spectroscopic studies are described and the new ionization schemes are summarized.status: publishe

Laser-spectroscopy studies of the nuclear structure of neutron-rich radium

International audienceThe neutron-rich radium isotopes, Ra222−233, were measured with Collinear Resonance Ionization Spectroscopy (CRIS) at the ISOLDE facility, CERN. The hyperfine structure of the 7s2S01→7s7pP13 transition was probed, allowing measurement of the magnetic moments, quadrupole moments, and changes in mean-square charge radii. These results are compared to existing literature values, and the new moments and change in mean-square charge radii of Ra231 are presented. Low-resolution laser spectroscopy of the very neutron-rich Ra233 has allowed the isotope shift and relative charge radius to be determined for the first time