Alpha-gamma decay studies of $$^{247}$$ Md

The European Physical Journal A - The goal of the present paper is twofold. First, a novel expansion many-body method applicable to superfluid open-shell nuclei, the so-called Bogoliubov in-medium...     

Decay studies of K isomers in 254No

A detailed $ \gamma$ spectroscopic decay study of two K isomers in ²⁵⁴No was performed. In addition to the previously reported $ \gamma$ lines two new transitions of E = 778 , 856keV could be attributed to the decay pattern of ^254m1No ( T _1/2 = 275±7 ms). The population of an excited band built up on this isomer ( $\ensuremath K^{\pi} =8^{-}$ by the decay of ^254m2No ( T _1/2 = 198±13 μs) could be proven by measuring delayed $ \gamma$ - $ \gamma$ coincidences between transitions stemming from the decay of both isomeric states. The energies of the band members could be established up to $\ensuremath I^{\pi} = 15^{-}$ . A spontaneous fission branch of (2.0±1.2)×10^-4 was measured for ^254m1No , an upper limit of $ \le$ 1.2×10^-4 was estimated for ^254m2No . These values demonstrate the high stability of multi-quasiparticle configurations against spontaneous fission. Evidence for an $ \alpha$ decay branch of ^254m1No in the order of 1×10^-4 was found.     

Early onset of ground state deformation in neutron deficient polonium isotopes

In-source resonant ionization laser spectroscopy of the even-A polonium isotopes (192-210,216,218)Po has been performed using the 6p(3)7s (5)S(2) to 6p(3)7p (5)P(2) (λ=843.38 nm) transition in the polonium atom (Po-I) at the CERN ISOLDE facility. The comparison of the measured isotope shifts in (200-210)Po with a previous data set allows us to test for the first time recent large-scale atomic calculations that are essential to extract the changes in the mean-square charge radius of the atomic nucleus. When going to lighter masses, a surprisingly large and early departure from sphericity is observed, which is only partly reproduced by beyond mean field calculations.     

The reaction 48Ca + 238U → 286112* studied at the GSI-SHIP

The fusion reaction of ⁴⁸Ca projectiles with ²³⁸U target nuclei was studied at the velocity filter SHIP of GSI in Darmstadt. Two decay chains were measured, which fully confirm data that were previously assigned to the isotope ²⁸³112 in experiments at the Flerov Laboratory in Dubna. Two other events are consistent with a 50% spontaneous-fission (SF) branch of this isotope. The mean value obtained for the half-life of ²⁸³112 is (6.9 ^+6.9 _-2.3 s, the α energy is (9.520±0.015) MeV, and the total kinetic energy (TKE) of SF is (238±14) MeV. The half-life of the α decay daughter nucleus ²⁷⁹Ds is (0.18 ^+0.32 _-0.07 s, and the TKE of SF is (210 ⁺³² _-11 MeV. The cross-section deduced from all four events is (0.72 ^+0.58 _-0.35 pb , measured at an excitation energy of 34.6MeV of the compound nucleus ²⁸⁶112.     

Determination of α-decay branching ratios for 178, 179Hg

The neutron-deficient nuclides ^{182, 183}Pb were produced at the Accelerator Laboratory of the University of Jyv?skyl? by bombarding a ¹⁰⁷Ag target with ⁷⁸Kr ions. The nuclei of interest were separated using the RITU gas-filled separator and their radioactive decays investigated using the GREAT spectrometer. Correlating the $ \alpha$ decays of these Pb isotopes with those of their respective Hg daughters allowed $ \alpha$ -decay branching ratios of $\ensuremath b_\alpha($ ^178Hg) = 89(4)% and $\ensuremath b_\alpha($ ^179Hg) = 75(4)% to be deduced.     

Alpha-gamma decay studies of 255No

The decay of ²⁵⁵No was investigated by means of α-γ spectroscopy. The isotope was produced in the reactions ²⁰⁸Pb(⁴⁸Ca, n)²⁵⁵No, , 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 isotones ²⁴⁷Cm and ²⁴⁹Cf as well as with data for ²⁵³No.