Restoring the valence-shell stabilization in Nd-140

A projectile Coulomb-excitation experiment was performed at the radioactive-ion beam facility HIE-ISOLDE at CERN to obtain E2 and M1 transition matrix elements of Nd-140 using the multistep Coulomb-excitation code GOSIA. The absolute M1 strengths, B(M1; 2(2)(-) -> 2(1)(+)) = 0.033(8)mu(2)(N), B(M1 ; 2(3)(+) -> 2(1)(+)) = 0.26(-0.10)(+0.11)mu(2)(N), and B(M1; 2(4)+ -> 2(1)(+)) <0.04 mu(2)(N) identify the 2(3)(+) state as the main fragment of the one-quadrupole-phonon proton-neutron mixed-symmetry state of Nd-140. The degree of F-spin mixing in Nd-140 was quantified with the determination of the mixing matrix element VF-mix <7(-7)(-13) keV.Peer reviewe

betabeta-delayed fission of isomers in 188Bi^188Bi

status: publishe

In-source laser spectroscopy of dysprosium isotopes at the ISOLDE-RILIS

A number of radiogenically produced dysprosium isotopes have been studied by in-source laser spectroscopy at ISOLDE using the Resonance Ionization Laser Ion Source (RILIS). Isotope shifts were measured relative to 152Dy in the 4f 10 6s 2 5I 8 (gs)→4f 10 6s6p (8,1) 8 o (418.8nm vac )resonance transition. The electronic factor, F, and mass shift factor, M, were extracted and used for determining the changes in mean-squared charge radii for 145mDy and 147mDy for the first time

Solving the Puzzles of the Decay of the Heaviest Known Proton-Emitting Nucleus 185Bi

Two long-standing puzzles in the decay of Bi185, the heaviest known proton-emitting nucleus are revisited. These are the nonobservation of the 9/2- state, which is the ground state of all heavier odd-A Bi isotopes, and the hindered nature of proton and α decays of its presumed 60-μs 1/2+ ground state. The Bi185 nucleus has now been studied with the Mo95(Nb93,3n) reaction in complementary experiments using the Fragment Mass Analyzer and Argonne Gas-Filled Analyzer at Argonne National Laboratory's ATLAS facility. The experiments have established the existence of two states in Bi185; the short-lived T1/2=2.8-1.0+2.3 μs, proton- and α-decaying ground state, and a 58(2)-μs γ-decaying isomer, the half-life of which was previously attributed to the ground state. The reassignment of the ground-state lifetime results in a proton-decay spectroscopic factor close to unity and represents the only known example of a ground-state proton decay to a daughter nucleus (Pb184) with a major shell closure. The data also demonstrate that the ordering of low- and high-spin states in Bi185 is reversed relative to the heavier odd-A Bi isotopes, with the intruder-based 1/2+ configuration becoming the ground, similar to the lightest At nuclides

Laser-assisted decay spectroscopy and mass spectrometry of 178Au^178Au

A comprehensive study of the isotope 178Au has been made at the CERN-ISOLDE facility, using resonance laser ionization. Two long-lived states in 178Au were identified—a low-spin ground state and a high-spin isomer—each of which were produced as pure beams. Using the ISOLTRAP precision Penning trap, the excitation energy of the isomeric state in 178Au was determined to be E∗=189(14)keV. The α-decay fine structure patterns of the two states were studied using the Windmill decay station, providing information on the low-lying states in the daughter nucleus 174Ir. Nuclear spin assignments of I(178Aug)=(2,3) and I(178Aum)=(7,8) are made based on the observed β-decay feeding and hyperfine structure intensity patterns. These spin assignments are used for fitting the hyperfine structures of the two states from which values for the magnetic dipole moments are extracted. The extracted moments are compared with calculations using additivity relations to establish the most probable configurations for 178Aug,m

Laser-assisted decay spectroscopy for the ground states of 180,182Au^180,182Au

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First -decay spectroscopy of and new -decay branches of

19 pags., 14 figs., 3 tabs.The  decay of the neutron-rich and was investigated experimentally in order to provide new insights into the nuclear structure of the tin isotopes with magic proton number above the shell. The -delayed -ray spectroscopy measurement was performed at the ISOLDE facility at CERN, where indium isotopes were selectively laser-ionized and on-line mass separated. Three -decay branches of were established, two of which were observed for the first time. Population of neutron-unbound states decaying via rays was identified in the two daughter nuclei of and , at excitation energies exceeding the neutron separation energy by 1 MeV. The -delayed one- and two-neutron emission branching ratios of were determined and compared with theoretical calculations. The -delayed one-neutron decay was observed to be dominant -decay branch of even though the Gamow-Teller resonance is located substantially above the two-neutron separation energy of . Transitions following the  decay of are reported for the first time, including rays tentatively attributed to . In total, six new levels were identified in on the basis of the coincidences observed in the and decays. A transition that might be a candidate for deexciting the missing neutron single-particle state in was observed in both  decays and its assignment is discussed. Experimental level schemes of and are compared with shell-model predictions. Using the fast timing technique, half-lives of the , and levels in were determined. From the lifetime of the state measured for the first time, an unexpectedly large transition strength was deduced, which is not reproduced by the shell-model calculations.M.P.-S. acknowledges the funding support from the Polish National Science Center under Grants No. 2019/33/N/ST2/03023 and No. 2020/36/T/ST2/00547 (Doctoral scholarship ETIUDA). J.B. acknowledges support from the Universidad Complutense de Madrid under the Predoctoral Grant No. CT27/16- CT28/16. This work was partially funded by the Polish National Science Center under Grants No. 2020/39/B/ST2/02346, No. 2015/18/E/ST2/00217, and No. 2015/18/M/ST2/00523, by the Spanish government via Projects No. FPA2017-87568-P, No. RTI2018-098868-B-I00, No. PID2019-104390GB-I00, and No. PID2019-104714GB-C21, by the U.K. Science and Technology Facilities Council (STFC), the German BMBF under Contract No. 05P18PKCIA, by the Portuguese FCT under the Projects No. CERN/FIS-PAR/0005/2017, and No. CERN/FIS-TEC/0003/2019, and by the Romanian IFA Grant CERN/ISOLDE. The research leading to these results has received funding from the European Union’s Horizon 2020 research and innovation programme under Grant Agreement No. 654002. M.Str. acknowledges the funding from the European Union’s Horizon 2020 research and innovation program under Grant Agreement No. 771036 (ERC CoG MAIDEN). J.P. acknowledges support from the Academy of Finland (Finland) with Grant No. 307685. Work at the University of York was supported under STFC Grants No. ST/L005727/1 and No. ST/P003885/1

Hyperfine anomaly in gold and magnetic moments of Ipi=11/2−I^pi=11/2^- gold isomers

status: publishe