0000000001267498
AUTHOR
D. O’donnell
Decays of new nuclides and isomers beyond the proton drip line - The influence of neutron configurations
Bozok University;Erciyes University;et al.;Istanbul University;Nigde University;The Turkish Atomic Energy Authority (TAEK)
Reduced transition probabilities along the yrast line in 166W
Lifetimes of excited states in the yrast band of the neutron-deficient nuclide 166W have been measured utilizing the DPUNS plunger device at the target position of the JUROGAM II γ -ray spectrometer in conjunction with the RITU gas-filled separator and the GREAT focal-plane spectrometer. Excited states in 166W were populated in the 92Mo(78Kr,4p) reaction at a bombarding energy of 380 MeV. The measurements reveal a low value for the ratio of reduced transitions probabilities for the lowest-lying transitions B(E2; 4+ → 2+)/B(E2; 2+ → 0+) = 0.33(5), compared with the expected ratio for an axially deformed rotor (B4/2 = 1.43). peerReviewed
Fine structure in the α decay of 156Lu and 158Ta
Fine structure in the α decay of high-spin states in 156Lu and 158Ta has been identified by means of αγ - coincidence analysis. One new α decay from 156Lu and two from 158Ta were identified, one of which was found to populate a previously unknown state in 154Lu. The hindrance-factor systematics from all four odd-odd, N = 85 nuclei with known α-decaying, πh11/2 coupled states were reviewed and are discussed. These proved consistent with the previously assigned (πh11/2νh9/2 )10+ configuration of the α-decaying state in 156Lu, which differs from the (πh11/2ν f7/2 )9+ assignments in the other three nuclei. peerReviewed
Quasiparticle alignments and α-decay fine structure of 175Pt
Excited states and decay properties of 175Pt have been investigated using the 92Mo(86Sr,2pn) fusion-evaporation reaction. The JUROGAM I γ -ray spectrometer and the GREAT spectrometer were used in conjunction with the gas-filled recoil separator RITU for the measurement of the radiation at the target and focal plane positions, respectively. Two new band structures, assigned to be based on the I π = (7/2 −) ground state in 175Pt, have been established and the known yrast band has been extended up to I π = (49/2 +). Rotational properties of the excited states in 175Pt have been investigated within the cranked shell-model formalism. The low-frequency changes in the alignments of the positive- a…
Competing Decay Modes of a High-spin Isomer in the Proton-unbound Nucleus 158Ta
An isomeric state at high spin and excitation energy was recently observed in the proton-unbound nucleus 158Ta. This state was observed to decay by both α and γ decay modes. The large spin change required to decay via γ-ray emission incurs a lifetime long enough for α decay to compete. The α decay has an energy of 8644(11) keV, which is among the highest observed in the region, a partial half-life of 440(70) µs and changes the spin by 11~. In this paper, additional evidence supporting the assignment of this α decay to the high-spin isomer in 158Ta will be presented. peerReviewed
Decay of a 19− isomeric state in 156Lu
A multiparticle spin-trap isomeric state having a half-life of 179(4) ns and lying 2601 keV above the yrast 10 + state in 156 Lu has been discovered. The 156 Lu nuclei were produced by bombarding isotopically enriched 106 Cd targets with beams of 58 Ni ions, separated in flight using the gas-filled separator RITU and their decays were measured using the GREAT spectrometer. Analysis of the main decay path that populates yrast states observed previously suggests a spin-parity assignment of 19 − for the isomeric state, which is consistent with isomeric states identified in the N = 85 isotones. Comparison with other decay paths in 156 Lu indicates that the [ π h − 1 11 / 2 ⊗ ν h 9 / 2 ] 10 + st…
Identification of a 6.6μs isomeric state in 175Ir
An experiment has been performed to study excited states in the neutron-deficient nucleus 175Ir via the use of the JUROGAM II high-purity germanium detector array and the RITU gas-filled separator at JYFL, Jyväskylä. By using isomer tagging, an isomeric state with a half-life of 6.58(15) μs has been observed in 175Ir for the first time. It has been established that the isomer decays via a 45.2 (E1)–26.1 (M1) keV cascade to new states below the previously reported ground state in 175Ir with Iπ = (5/2−). We now reassign this (5/2−) state to the isomeric state discovered in this study. peerReviewed
Lifetime measurements of yrast states in ¹⁷⁸ Pt using the charge plunger method with a recoil separator
Abstract Lifetime measurements in \(^{178}\)Pt with excited states de-exciting through \(\gamma\)-ray transitions and internal electron conversions have been performed. Ionic charges were selected by the in-flight mass separator MARA and measured at the focal plane in coincidence with the \(4^{+}_{1}→2^{+}_{1}\) 257 keV γ-ray transition detected using the JUROGAM 3 spectrometer. The resulting charge-state distributions were analysed using the differential decay curve method (DDCM) framework to obtain a lifetime value of 430(20) ps for the \(2^{+}_{1}\) state. This work builds on a method that combines the charge plunger technique with the DDCM analysis. As an alternative analysis, ions were…
Fine structure in the α decay of high-spin isomers in 155Lu and 156Hf
Fine structure in the α decay of high-spin isomers in 155Lu(25/2−) and 156Hf (8+) has been studied for the first time using αγ -coincidence analysis. Three new α decays from 155Lu(25/2−) and two from 156Hf (8+) have been identified, populating seniority s > 1 states in the N = 82 nuclei 151Tm and 152Yb, respectively. The reduced hindrance factors of the α decays support the previous configuration assignments of the populated states. This is the first observation of states with excitation energy greater than 1.5 MeV being populated following α decay in nuclei outside of the 208Pb region. peerReviewed
A charge plunger device to measure the lifetimes of excited nuclear states where transitions are dominated by internal conversion
A charge plunger device has been commissioned based on the DPUNS plunger (Taylor et al., 2013) using the in-flight mass separator MARA at the University of Jyväskylä. The 152Sm(32S,4n)180Pt reaction was used to populate excited states in 180Pt. A lifetime measurement of the 21+ state was performed by applying the charge plunger technique, which relies on the detection of the charge state-distribution of recoils rather than the detection of the emitted γ rays. This state was a good candidate to test the charge plunger technique as it has a known lifetime and depopulates through a converted transition that competes strongly with γ-ray emission. The lifetime of the 21+ state was measured to be…
Spectroscopy of the neutron-deficient isobars 163 Re and 163 W using tagging techniques
Bozok University;Erciyes University;et al.;Istanbul University;Nigde University;The Turkish Atomic Energy Authority (TAEK)
High-spin states in the neutron-rich A∼100 region
Two experimental setups have been used to study excited states of neutron‐rich nuclei in the A∼100 region. Extended level schemes and lifetime measurements were obtained using deep‐inelastic and fusion‐fission reactions with the CLARA‐PRISMA spectrometer and the Ge‐array GASP respectively. Experimental information from GASP has been used to complement the CLARA‐PRISMA experiment. Time spectra have been used to measure the lifetimes of isomeric states. Preliminary results are presented for 89Rb.
Characterizing the atomic mass surface beyond the proton drip line via {\alpha}-decay measurements of the {\pi}s1/2 ground state of 165Re and the {\pi}h11/2 isomer in 161Ta
The α-decay chains originating from the πs1/2 and πh11/2 states in 173Au have been investigated following fusion-evaporation reactions. Four generations of α radioactivities have been correlated with 173Aum leading to a measurement of the α decay of 161Tam. It has been found that the known α decay of 161Ta, which was previously associated with the decay of the ground state, is in fact the decay of an isomeric state. This work also reports on the first observation of prompt γ rays feeding the ground state of 173Au. This prompt γ radiation was used to aid the study of the α-decay chain originating from the πs1/2 state in 173Au. Three generations of α decays have been correlated with this stat…