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International audience; The decay of excited states in No255 was investigated by applying the evaporation-residue–conversion-electron correlation technique. Two new isomeric states were observed in No255 together with the previously known one. Excitation energies of the isomeric states were estimated based on the energies of conversion electrons and γ rays from correlation chains. These results were in accord with theoretical calculations based on the mean-field models. A tentative decay scheme of isomeric states in No255 is proposed, and their Nilsson configurations are discussed. The energy decrease of the 11/2−[725] Nilsson level for heavy N=153 isotones as a function of increasing proton number is confirmed.

The neutron-deficient gold (Z=79) isotopes in the vicinity of the neutron midshell N=104 provide prolific examples of shape coexistence and isomerism at low excitation energy. They can be probed via a number of different experimental techniques. In this study, two new isomeric states with half-lives of 294(7) and 373(9) ns have been observed in the neutron-deficient odd-odd nuclide Au178 (N=99) in an experiment at the RITU gas-filled separator at JYFL, Jyvaskyla. This result was achieved due to the use of a segmented planar germanium detector with a high efficiency at low energies. By applying the recoil-decay tagging technique, they were assigned to decay to two different long-lived α-decaying states in Au178.

The $$\upbeta ^+$$ /EC decay of mass separated samples of $$^{181}$$ Hg was studied employing the TATRA spectrometer at the ISOLDE facility at CERN. The decay scheme was constructed for the first time. A Broad Energy Germanium detector was used to achieve this by combination of high-gain $$\upgamma $$ -ray singles spectroscopy and $$\upgamma $$ – $$\upgamma $$ coincidences. The systematics of excited states associated with the 1 $$h_{11/2}$$ proton-hole configuration in odd-Au isotopes was extended.

The extremely neutron-deficient isotopes 177,179Au were studied by means of in-beam ?-ray spectroscopy. Specific tagging techniques, ?-decay tagging in 177Au and isomer tagging in 179Au, were used for these studies. Feeding of positive-parity, nearly spherical states, which are associated with 2d3/2 and 3s1/2 proton-hole configurations, from the 1i13/2 proton-intruder configuration was observed in 177Au. Such a decay path has no precedent in odd-Au isotopes and it is explained by the effect of mixing of wave functions of the initial state. © 2020, 262010 2/0129/17 Science and Technology Facilities Council, STFC European Research Council, ERC: 203481 Academy of Finland: 131665 Agentúra na Podporu V?skumu a V?voja, APVV: APVV-15-0225, The authors express their gratitude to the staff of the Accelerator Laboratory at the University of Jyväskylä for their excellent technical support. This work has been supported by the EU-FP7-IA project ENSAR (No. 262010 ), the Academy of Finland (CoE in Nuclear and Accelerator Based Physics, grant to T.G., Contract No. 131665 ), the European Research Council through the project SHESTRUCT (Grant Agreement No. 203481 ), the UK Science and Technology Facilities Council , the Slovak Research and Development Agency under Contract No. APVV-15-0225 , and the Slovak Grant Agency VEGA (Contract No. 2/0129/17 ).

A new automated method has been developed with the aim to correct measured spectra for sudden gain and offset drifts due to temporal instrumentation instabilities. It is based on discrete cross-correlation that alleviates the need for Gaussian-shaped peaks and is capable of correcting spectra that change their shape in time. Potential of this method has been tested on decay and in-beam γ -ray spectroscopy data measured with an array of three n-type coaxial High-Purity Germanium detectors albeit its use is not limited only for γ -ray spectroscopy.

A compact and versatile tape transport system for the collection and counting of radioactive samples from radioactive ion beam facilities has been developed. It uses an amorphous metallic tape for transportation of the activity. Because of this material, the system can hold very good vacuum, typically below 10 − 7 mbar .

The first accurate measurements of the α-decay branching ratio and half-life of the I π = 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, I π = 1 / 2 + states in the neutron-deficient lead region. The findings shed light on the unexpected hindrance of the 1 / 2 + → 1 / 2 + , 181Tl → g 177 Aug α decay, which is explained by a mixing of π 3 s 1 / 2 and π 2 d 3 / 2 configurations in 177Aug, whilst 181Tlg remains a near-pure π 3 s 1 / 2 . This conclusion is inferred from the g factor of 177Aug which has an intermediate value between those of π 3 s 1 / 2 and π 2 d 3 / 2 states. A similar mixed configuration is proposed for the I π = 1 / 2 + ground state of 179Au. This mixing may provide evidence for triaxial shapes in the ground states in these nuclei.

Physics letters / B 748, 89 - 94 (2015). doi:10.1016/j.physletb.2015.06.068, Published by North-Holland Publ., Amsterdam

A detailed $\alpha$-decay spectroscopy study of $^{180}\mathrm{Tl}$ has been performed at ISOLDE (CERN). $Z$-selective ionization by the Resonance Ionization Laser Ion Source (RILIS) coupled to mass separation provided a high-purity beam of $^{180}\mathrm{Tl}$. Fine-structure $\alpha$ decays to excited levels in the daughter $^{176}\mathrm{Au}$ were identified and an $\alpha$-decay scheme of $^{180}\mathrm{Tl}$ was constructed based on an analysis of $\alpha$-$\gamma$ and $\alpha$-$\gamma$-$\gamma$ coincidences. Multipolarities of several $\gamma$-ray transitions deexciting levels in $^{176}\mathrm{Au}$ were determined. Based on the analysis of reduced $\alpha$-decay widths, it was found that all $\alpha$ decays are hindered, which signifies a change of configuration between the parent and all daughter states.

Excited states in the proton-unbound nuclide $^{177}$Au were populated in the $^92}$Mo($^{88}$Sr, p2n) reaction and identified using the Jurogam-II and GREAT spectrometers in conjunction with the RITU gas-filled separator at the University of Jyvaskyla Accelerator Laboratory. A strongly coupled band and its decay path to the 11/2−α-decaying isomer have been identified using recoil-decay tagging. Comparisons with cranked Hartree-Fock-Bogoliubov (HFB) calculations based on Skyrme energy functionals suggest that the band has a prolate deformation and is based upon coupling the odd 1h11/2 proton hole to the excited 02+ configuration in the $^{178}$Hg core. Although these configurations might be expected to follow the parabolic trend of core Hg(02+) states as a function of neutron number, the electromagnetic decay paths from the strongly coupled band in $^{177}$Au are markedly different from those observed in the heavier isotopes above the midshell. This indicates that a significant change in the structure of the underlying A+1Hg core occurs below the neutron midshell.

Hyperfine structure and isotope shifts have been measured for the ground and isomeric states in the neutron-deficient isotopes $^{179--184}\mathrm{Tl}$ using the 276.9-nm transition. The experiment has been performed at the CERN-Isotope Separator On-Line facility using the in-source resonance-ionization laser spectroscopy technique. Spins for the ground states in $^{179,181,183}\mathrm{Tl}$ have been determined as $I=1/2$. Magnetic moments and changes in the nuclear mean-square charge radii have been deduced. By applying the additivity relation for magnetic moments of the odd-odd Tl nuclei the leading configuration assignments were confirmed. A deviation of magnetic moments for isomeric states in $^{182,184}\mathrm{Tl}$ from the trend of the heavier Tl nuclei is observed. The charge radii of the ground states of the isotopes $^{179--184}\mathrm{Tl}$ follow the trend for isotonic (spherical) lead nuclei. The noticeable difference in charge radii for ground and isomeric states of $^{183,184}\mathrm{Tl}$ has been observed, suggesting a larger deformation for the intruder-based $9/{2}^{\ensuremath{-}}$ and ${10}^{\ensuremath{-}}$ states compared to the ground states. An unexpected growth of the isomer shift for $^{183}\mathrm{Tl}$ has been found.

A recently developed portable, on-line capability for γ-ray and conversion-electron spectroscopy, HIGH-TATRA is demonstrated with its application to the study of (183)Hg $\to $ (183)Au at ISOLDE. Key details of the low-energy level scheme of the neutron-deficient nuclide (183)Au populated in this decay are presented. A broad energy germanium detector is employed to achieve this (the first-ever use of such a device in decay-scheme spectroscopy), by way of a combination of high-gain γ-ray singles spectroscopy and γ–γ coincidence spectroscopy. Further, by combining the γ-ray detectors with a liquid-nitrogen-cooled Si(Li) detector operated under high vacuum, conversion-electron singles and e–γ coincidences are obtained. These data lead to the determination of transition multipolarities and the location of a highly converted (E0 + M1 + E2) transition in the (183)Au decay scheme, suggesting a possible new shape coexisting structure in this nucleus. Identification of new intruder and normal states fixes their relative energies in (183)Au for the first time. New systematic features in the odd-Au isotopes are presented.

International audience; The ${\beta }^{+}$/EC decay of ${}^{\mathrm{182,184}}$Tl to excited states in the daughter nuclei ${}^{\mathrm{182,184}}$Hg has been investigated at the CERN on-line isotope mass separator facility. In both Tl nuclei two β-decaying states were observed. In the case of (184)Tl, narrow-band laser spectroscopy could be used to disentangle the decay of both isomers. In (182)Hg a precise energy of 335 (1) keV for the ${0}_{2}^{+}$ state was measured together with its feeding from a tentatively proposed ${2}_{3}^{+}$ state at 973 keV. Large conversion coefficients for the ${2}_{2}^{+}\to {2}_{1}^{+}$ transition in ${}^{\mathrm{182,184}}$Hg were measured to be 7.2 (13) and 14.2 (36), respectively, evidencing a strong E0 component.

In-gas-cell laser ionization spectroscopy studies on the neutron deficient 97–101Ag isotopes have been performed with the LISOL setup. Magnetic dipole moments and mean-square charge radii have been determined for the first time with the exception of 101Ag, which was found in good agreement with previous experimental values. The reported results allow tentatively assigning the spin of 97,99Ag to 9 2 and confirming the presence of an isomeric state in these two isotopes, whose collapsed hyperfine structure suggests a spin of 1 2 . The effect of the N = 50 shell closure is not only manifested in the magnetic moments but also in the evolution of the mean-square charge radii of the isotopes investigated, in accordance with the spherical droplet model predictions.

Fission barrier height is one of the least known nuclear parameters, with experimental data, acquired decades ago, existing only close to beta-stability line. Availability of heavy radioactive beams offers possibility to investigate fission of more exotic nuclei and using the state of the art detection technique such as the active target we can even probe their fission barriers heights with precision has not been reached so far. The present status of fission barrier measurement is going to be explained in this paper. We are going to discuss the possibilities to stage experimental studies of fission barrier heights at new generation of ISOL facilities such as HIE-ISOLDE and active target ACTAR TPC. As an example we select the experiment IS581, being prepared for execution at the HIE-ISOLDE facility (CERN).

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. ispartof: Physics Letters B vol:719 issue:4 pages:362-366 status: published

In the present study, $B(E2; 2^{+}_{1}\rightarrow 0^{+}_{1})$ values have been measured in the 208,210Rn and 206Po nuclei through Coulomb excitation of re-accelerated radioactive beams in inverse kinematics at CERN-ISOLDE. These nuclei have been proposed to lie in, or at the boundary of the region where the seniority scheme should persist. However, contributions from collective excitations are likely to be present when moving away from the N=126 closed shell. Such an effect is confirmed by the observed increased collectivity of the $2^{+}_{1}\rightarrow 0^{+}_{1}$ transitions. Experimental results have been interpreted with the aid of theoretical studies carried out within the BCS-based QRPA framework.

The isotope 261Sg and its decay product 257Rf were produced in the nuclear reaction 208Pb(54Cr, n)261Sg . The radioactive decay of these isotopes was investigated by means of $ \alpha$ , $ \alpha$ - $ \gamma$ and/or $ \alpha$ -X-ray spectroscopy. Improved spectroscopic data concerning $ \alpha$ energies, $ \gamma$ transitions, tentative spin and parity assignments of low-lying Nilsson single-neutron orbitals are presented for these nuclei.

The radioactive decay of the isotopes 254-256Lr and their daughter products was investigated by means of α , prompt α -γ and delayed conversion electron-γ coincidence spectroscopy. The isotopes were produced using the reaction 48Ca + 209Bi .

A K isomer with a half-life of (110±10) ms at an excitation energy of 1254keV has been identified in the nucleus 252No . The isomer is interpreted as a two-quasineutron state with K π = 8- . The isotope 252No was produced in the fusion-evaporation reaction 206Pb(48Ca, 2n)252No . The experiment has been performed at the velocity filter SHIP of GSI Darmstadt.

Decay spectroscopy of $^{184}\mathrm{Tl}$ has been performed at the CERN Isotope Separator On-Line (ISOLDE) facility. An excitation energy of 506.1(1) keV and a half-life of 47.1(7) ms of the intruder based $({10}^{\ensuremath{-}})$ state have been extracted. The internal decay characteristics of this state are determined and discussed, extending the systematics of such states in the even-mass thallium nuclei below neutron midshell at $N=104$. The retardation factors of the isomeric $M2$ and $E3$ transitions are deduced and compared with retardation factors in neighboring odd-mass and even-mass thallium isotopes. The new information is combined with a review of hindered and unhindered $\ensuremath{\alpha}$-decay data of $^{187--192}\mathrm{Bi}$ populating levels in daughter nuclei $^{183--188}\mathrm{Tl}$ and supports the interpretation of the intruder character of the $({10}^{\ensuremath{-}})$ state in $^{184}\mathrm{Tl}$.

The low-energy structure of the neutron-rich nucleus Ni-68 has been investigated by measuring the beta decay of the low-spin isomer in Co-68 selectively produced in the decay chain of Mn-68. A revised level scheme has been built based on the clear identification of beta-gamma-E0 delayed coincidences. Transitions between the three lowest-lying 0(+) and 2(+) states are discussed on the basis of measured intensities or their upper limits for unobserved branches and state-of-the-art shell model calculations.

The decay of the isotopes 255Rf, 251No and 247Fm produced in the reactions $\mathrm{{}^{207}Pb\ensuremath({}^{50}Ti,2n){}^{255}Rf\ {}^{\alpha}_{\rightarrow}\ {}^{251}No\ \ensuremath{}^{\alpha}_{\rightarrow}\ {}^{247}Fm}$ , and $\mathrm{{}^{206}Pb\ensuremath({}^{48}Ca,3n){}^{251}No\ \ensuremath{}^{\alpha}_{\rightarrow}\ {}^{247}Fm}$ was investigated by means of α-γ spectroscopy. Previously observed γ transitions in coincidence with α decays of 255Rf were confirmed, their energies and line intensities were measured more precisely, and their multipolarities were determined as E1. In 251No a new isomeric state at E * > 1700keV with a half-life of ≈ 2μs was identified. The decay of 247Fm was measured more precisely. A partial level scheme of the daughter nucleus 243Cf could be established.

WOS: 000240847400007, The observation of the new nuclide Re-159(75)84 provides important insights into the evolution of single-particle structure and the mass surface in heavy nuclei beyond the proton drip line. This nuclide, 26 neutrons away from the nearest stable rhenium isotope, was synthesised in the reaction Cd-106(Ni-58, p4n) and identified via its proton radioactivity using the RITU gas-filled separator and the GREAT focal-plane spectrometer. Comparisons of the measured proton energy (E-p = 1805 +/- 20 keV) and decay half-life (t(1/2) = 21 +/- 4 mu s) with values calculated using the WKB method indicate that the proton is emitted from an h(11/2) state. The implications of these results for future experimental investigations into even more proton unbound nuclei using in-flight separation techniques are considered. (c) 2006 Elsevier B.V. All rights reserved., Science and Technology Facilities Council [EP/C543157/1, EP/C015371/1, EP/C015266/1, ST/G008671/1]

The decay of 255No was investigated by means of α-γ spectroscopy. The isotope was produced in the reactions 208Pb(48Ca, n)255No, \(\mathrm{{}^{209}Bi({}^{48}Ca,2n){}^{255}Lr \ {}^{\ensuremath \mathit{EC}}_{\rightarrow}\ {}^{255}No}\), and $238U(22Ne, 5n)255No$. Levels of the daughter nucleus 251Fm were assigned by α-γ coincidence measurements and on the basis of systematics. Level energies were determined precisely using measured γ-rays. The results are compared with the known level schemes of the lighter \(\ensuremath N=151\) isotones 247Cm and 249Cf as well as with data for 253No.

The stability of an atomic nucleus is determined by the outcome of a tug-of-war between the attractive strong nuclear force and the repulsive electrostatic force between the protons in the nucleus. If 100 protons and about 150 neutrons or more are assembled into a nucleus, the repulsion usually becomes dominant and causes the nucleus to fission. For certain 'magic numbers' of protons and neutrons this repulsion can be overcome and the nucleus stabilized. In particular an 'island of stability' is predicted beyond the actinides, where long-lived or even stable superheavy elements can exist, but its precise limits are unknown. Experiments can help determine where this island lies, however. Spectroscopy of the nobelium isotope, 254No reveals three excited structures, two of them metastable. This finding will help to constrain nuclear models of the superheavy elements, and provides more data for the search for the next magic numbers. Spectroscopic studies of the nobelium isotope 254No — the heaviest nucleus studied in this manner to date — details three excited structures, two of which are metastable, which should help to constrain nuclear models of the superheavy elements. A long-standing prediction of nuclear models is the emergence of a region of long-lived, or even stable, superheavy elements beyond the actinides. These nuclei owe their enhanced stability to closed shells in the structure of both protons and neutrons1,2,3. However, theoretical approaches to date do not yield consistent predictions of the precise limits of the ‘island of stability’; experimental studies are therefore crucial. The bulk of experimental effort so far has been focused on the direct creation of superheavy elements in heavy ion fusion reactions, leading to the production of elements up to proton number Z = 118 (refs 4, 5). Recently, it has become possible to make detailed spectroscopic studies6,7 of nuclei beyond fermium (Z = 100), with the aim of understanding the underlying single-particle structure of superheavy elements. Here we report such a study of the nobelium isotope 254No, with 102 protons and 152 neutrons—the heaviest nucleus studied in this manner to date. We find three excited structures, two of which are isomeric (metastable). One of these structures is firmly assigned to a two-proton excitation. These states are highly significant as their location is sensitive to single-particle levels above the gap in shell energies predicted at Z = 114, and thus provide a microscopic benchmark for nuclear models of the superheavy elements.

Isomeric states in No-254 were investigated using a calorimetric method. Two different isomers were found with half-lives of T-1/2 = 266 +/- 2 ms and T-1/2 = 184 +/- 3 mu s, respectively. The domin ...

The isotope $^{176}\mathrm{Au}$ has been studied in the complete fusion reaction $^{40}\mathrm{Ca}+^{141}\mathrm{Pr} \phantom{\rule{0.28em}{0ex}}\ensuremath{\rightarrow} {}^{176}\mathrm{Au}+5n$ at the velocity filter SHIP (GSI, Darmstadt). The complex fine-structure $\ensuremath{\alpha}$ decay of two isomeric states in $^{176}\mathrm{Au}$ feeding several previously unknown excited states in the daughter nucleus $^{172}\mathrm{Ir}$ is presented. An $\ensuremath{\alpha}$-decay branching ratio of ${b}_{\ensuremath{\alpha}}=9.5(11)%$ was deduced for the high-spin isomer in $^{172}\mathrm{Ir}$.

Decay properties of the neutron-deficient nuclides ${}^{201--203}\mathrm{Ra}$ and ${}^{200--202}\mathrm{Fr}$ were investigated using $\ensuremath{\alpha}$- and $\ensuremath{\gamma}$-decay spectroscopy. The nuclei were produced in fusion-evaporation reactions of ${}^{56}$Fe projectiles with enriched ${}^{147}$Sm and ${}^{149}$Sm targets at the velocity filter SHIP at GSI in Darmstadt (Germany). The $\ensuremath{\alpha}$ decay from the (3/2${}^{\ensuremath{-}}$) state in ${}^{201}$Ra was identified with an energy ${E}_{\ensuremath{\alpha}}=7842(12)$ keV and half-life ${T}_{1/2}={8}_{\ensuremath{-}4}^{+40}$ ms. Ambiguous decay properties for ${}^{202}$Ra from previous measurements were clarified by remeasuring with significantly improved precision, resulting in values of ${E}_{\ensuremath{\alpha}}=7722(7)$ keV and ${T}_{1/2}=3.{8}_{\ensuremath{-}0.8}^{+1.3}$ ms. New short-lived isomeric states were identified in ${}^{200}$Fr and ${}^{201}$Fr with half-lives of 0.6${}_{\ensuremath{-}0.2}^{+0.5}$ $\ensuremath{\mu}$s and 0.7${}_{\ensuremath{-}0.2}^{+0.5}$ $\ensuremath{\mu}$s, respectively. A tentative spin and parity of 13/2${}^{+}$ were assigned to the latter. One event attributed to $\ensuremath{\beta}$-delayed fission of ${}^{200}$Fr was observed.

Hyperfine splitting parameters have been measured for the neutron-deficient odd-mass polonium isotopes and isomers 193?203Pog,m, 209,211Po. The measurement was performed at the ISOLDE (CERN) online mass separator using the in-source resonance ionization spectroscopy technique. The magnetic dipole moments ? and spectroscopic electric quadrupole moments QS have been deduced. Their implication for the understanding of nuclear structure in the vicinity of the closed proton shell at Z = 82 and the neutron mid-shell at N = 104 is discussed. For the most neutron-deficient nuclei (A = 193,195,197), a deviation of ? and QS from the nearly constant values for heavier polonium nuclei was observed. Particle-plus-rotor calculations with static oblate deformation describe the electromagnetic moments for these nuclei well, provided a gradual increase of a mean deformation when going to lighter masses is assumed for the polonium nuclei with A < 198.

A detailed nuclear-decay spectroscopy study of the neutron-deficient isotope 178Tl has been performed using the highly selective Resonance Ionization Laser Ion Source and ISOLDE mass separator (CERN), which allowed a unique isobarically pure beam of 178Tl to be produced. The first identification of the $\beta$-delayed fission of this isotope was made and its probability P$\beta$DF(178Tl) = 0.15(6)\% was determined. An asymmetric fission fragment mass distribution of the daughter isotope 178Hg (populated by the $\beta$ decay of 178Tl) was deduced based on the measured fission fragment energies. The fine-structure $\alpha$-decay pattern of 178Tl allowed the low-energy states in the daughter nucleus 174 Au to be studied.

A detailed $\ensuremath{\beta}$-decay study of ${}^{61}$Mn is presented, yielding extended information on the level structure of ${}^{61}$Fe. Pure beams were obtained at ISOLDE, CERN, after selective laser ionization and mass separation of fission products from the bombardment of a UC${}_{x}$ target by 1.4-GeV protons. The $\ensuremath{\beta}$ and $\ensuremath{\gamma}$ information was detected by two MiniBall clusters and three $\ensuremath{\Delta}$$E$ plastic scintillators. The new ${}^{61}$Mn decay scheme reveals 48 $\ensuremath{\gamma}$ transitions, distributed over 20 excited states. A comparison to the decay scheme of ${}^{59}$Mn and excited states in ${}^{59}$Fe is made. Shell-model calculations with two different interactions are performed in order to compare the nuclear structure of the two neighboring odd-$A$ iron isotopes. Tentative spin and parities of several excited states in ${}^{61}$Fe are assigned on the basis of $\ensuremath{\beta}$-decay feeding patterns in both ${}^{59,61}$Fe and of results from the theoretical shell-model calculations.

Very neutron deficient francium isotopes have been produced in fusion evaporation reactions using ${}^{60}$Ni ions on ${}^{141}$Pr targets. The gas-filled recoil separator RITU was employed to collect the fusion products and to separate them from the scattered beam. The activities were implanted into a position sensitive silicon detector after passing through a gas-counter system. The isotopes were identified using spatial and time correlations between the implants and the decays. Two $\ensuremath{\alpha}$-particle activities, with ${E}_{\ensuremath{\alpha}}=7613(15)$ keV and ${T}_{1/2}$ $=$ (${15}_{\ensuremath{-}5}^{+12}$) ms and ${E}_{\ensuremath{\alpha}}=7684(15)$ keV and ${T}_{1/2}$ $=$ (${16}_{\ensuremath{-}5}^{+13}$) ms were identified in the new isotope ${}^{198}$Fr. In addition, the half-life and $\ensuremath{\alpha}$-particle energy of ${}^{199}$Fr were measured with improved precision. The measured decay properties deduced for ${}^{199}$Fr and ${}^{198}$Fr suggest that there is an onset of ground-state deformation at $N=112$ in the Fr isotopes.

Detailed $\ensuremath{\alpha}$-decay studies of ${}^{179}$Tl${}^{g}$ and its daughter products ${}^{175}$Au${}^{g}$ and ${}^{171}$Ir${}^{g}$ were carried out in two complementary experiments at the mass separator ISOLDE (CERN) and velocity filter SHIP (GSI). First unambiguous determination of the $\ensuremath{\alpha}$-decay properties of ${}^{175}$Au${}^{g}$ was performed as follows: ${E}_{\ensuremath{\alpha}}$ $=$ 6433(4) keV, ${T}_{1/2}$ $=$ 207(7) ms, and $\ensuremath{\alpha}$-decay branching ratio 90(7)$%$. First determination of the $\ensuremath{\alpha}$-decay branching ratios for ${}^{179}$Tl${}^{g}$ and ${}^{171}$Ir${}^{g}$ was also made: ${b}_{\ensuremath{\alpha}}$(${}^{179}$Tl${}^{g}$) $=$ 60(2)$%$ and ${b}_{\ensuremath{\alpha}}$(${}^{171}$Ir${}^{g}$) $=$ 15(2)$%$. The spins of the ground states in ${}^{175}$Au and ${}^{171}$Ir are established as 1/2${}^{+}$.

Excited states in the neutron-deficient isotopes Os-163 and Os-165 were identified using the JUROGAM and GREAT spectrometers in conjunction with the RITU gas-filled separator. The Os-163 and Os-165 nuclei were populated via the Cd-106(Ni-60,3n) and Mo-92(Kr-78,2p3n) 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 f(7/2) and h(9/2) orbitals.

The radioactive element astatine exists only in trace amounts in nature. Its properties can therefore only be explored by study of the minute quantities of artificially produced isotopes or by performing theoretical calculations. One of the most important properties influencing the chemical behaviour is the energy required to remove one electron from the valence shell, referred to as the ionization potential. Here we use laser spectroscopy to probe the optical spectrum of astatine near the ionization threshold. The observed series of Rydberg states enabled the first determination of the ionization potential of the astatine atom, 9.31751(8) eV. New ab initio calculations are performed to support the experimental result. The measured value serves as a benchmark for quantum chemistry calculations of the properties of astatine as well as for the theoretical prediction of the ionization potential of superheavy element 117, the heaviest homologue of astatine., The application of astatine, one of the rarest elements on the earth, in the treatment of cancer requires a better understanding of its chemistry. Rothe et al. report the first measurement of the ionization potential of astatine, against which high-level quantum calculations are benchmarked.

In the present study, B( E2; 2(+)-> 0(+) ) values have been measured in the Rn-208 and Po-206 nuclei through Coulomb excitation of re-accelerated radioactive beams in inverse kinematics at CERN-ISOLDE. The resulting B(E2; 2(+)-> 0(+)) in 208Rn is similar to 0.08 e(2)b(2). These nuclei lie in, or at the boundary of the region where seniority scheme should persist. However, contributions from collective excitations may be present when moving away from the N = 126 shell closure. To date, surprisingly little is known of the transition probabilities between the low-spin states in this region.

The ${}^{64}$Co $\ensuremath{\beta}$-decay feeding levels in the well-studied ${}^{64}$Ni nucleus were investigated. Whereas the previously known ${}^{64}$Co decay scheme merely contained 2 $\ensuremath{\gamma}$ rays, the decay scheme established in this work contains $18,$ of which 5 are observed in this work and 6 were previously observed in an ($n$,$\ensuremath{\gamma}$) study but not placed in the ${}^{64}$Ni level scheme. Surprisingly, one additional level---placed at an excitation energy of $3578.7$ keV---could be determined. The observed $\ensuremath{\beta}$-decay paths involve allowed $\ensuremath{\nu}{f}_{5/2}\ensuremath{\rightarrow}\ensuremath{\pi}{f}_{7/2}$ and $\ensuremath{\nu}{p}_{1/2}\ensuremath{\rightarrow}\ensuremath{\pi}{p}_{3/2}$ transitions. Three strongly fed levels around 4 MeV are interpreted to possess possible proton-intruder character.