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This work presents new evaluation of A=105 nuclear structure and decay data. It covers a range of nuclei from the very neutron-rich 10538Sr to the extremely neutron-deficient 10552Te, known also to be the doughter of the lightest alpha decaying nucleus 109I. The work is based on experimental studies performed in the last 73 years, where A=105 nuclei were produced in particle transfer, fusion/evaporation reactions, sponataneus and induced fission, fusion and fragmentation of relativistic beams, radioactive decay etc.

Fast-timing measurements at the focal plane of a separator can suffer from poor timing resolution. This is due to the variations in time-of-flight (ToF) for photons travelling to a given detector, which arise from the changes in the implantation positions of the recoil nuclei emitting the γ rays of interest. In order to minimise these effects on timing measurements, a procedure is presented that improves fast-timing data by performing ToF corrections on an event-by-event basis. This method was used to correct data collected with an array of eight LaBr 3 detectors, which detected γ rays from spatially distributed 138Gd recoil-implants at the focal plane of the Recoil-Ion-Transport-Unit (RITU) spectrometer. The Generalised Centroid Difference (GCD) method was used to extract a lifetime from data in conjunction with a new procedure to calibrate the time walk. The lifetime of the first 2 + state in 138Gd, populated by the decay of the K π = 8 − isomeric state, was measured to be 229(24) ps using the ToF-corrected data, which is consistent within three standard deviations to the literature value. The results together with Monte-Carlo simulations show that the ToF correction procedure reduced the uncertainty in the measured lifetimes by 3 % in the case of the spatially distributed nuclei at the focal plane of RITU. However, ∼ 12 % has been estimated for a similar experiment when using a larger focal plane i.e. the Super-FRS at the FAIR facility.

In-flight fission of a 345 MeV per nucleon 238U primary beam on a 2 mm thick 9Be target has been used to produce and study the decays of a range of neutron-rich nuclei centred around the doubly mid-shell nucleus 170Dy at the RIBF Facility, RIKEN, Japan. The produced secondary fragments of interest were identified eventby- event using the BigRIPS separator. The fragments were implanted into the WAS3ABI position sensitive silicon active stopper which allowed pixelated correlations between implants and their subsequent β-decay. Discrete γ-ray transitions emitted following decays from either metastable states or excited states populated following beta decay were identified using the 84 coaxial high-purity germanium (HPGe) detectors of the EURICA spectrometer, which was complemented by 18 additional cerium-doped lanthanum bromide (LaBr3)

Physics letters / B 762, 404 - 408 (2016). doi:10.1016/j.physletb.2016.09.058, Published by North-Holland Publ., Amsterdam

We present a brief report on the progress towards the construction of the National Nuclear Array (NANA), a gamma-ray coincidence spectrometer for discrete-line nuclear structure and decay measurements. The proposed spectrometer will combine a gamma-ray energy resolution of approximately 3% at 1MeV with sub-nanosecond timing discrimination between successive gamma rays in mutually coincident decay cascades. We also review a number of recent measurements using coincidence fast-timing gamma-ray spectroscopy for nuclear structure studies, which have helped to inform the design criteria for the NANA spectrometer.

The first fast-timing measurements from nuclides produced via the in-flight fission mechanism are reported. The lifetimes of the first 2+states in 104,106Zr nuclei have been measured via β-delayed γ-ray timing of stopped radioactive isotope beams. An improved precision for the lifetime of the 2+1state in 104Zr was obtained, τ(2+1) =2.90+25−20ns, as well as a first measurement of the 2+1state in 106Zr, τ(2+1) =2.60+20−15ns, with corresponding reduced transition probabilities of B(E2; 2+1→0+g.s.) =0.39(2)e2b2and 0.31(1)e2b2, respectively. Comparisons of the extracted ground-state deformations, β2=0.39(1)(104Zr) and β2=0.36(1)(106Zr) with model calculations indicate a persistence of prolate deformation. The data show that 104Zr is the most deformed of the neutron-rich Zr isotopes measured so far.

Evaluated nuclear structure and decay data for all nuclei within the A = 112 mass chain are presented. The experimental data are evaluated and best values for level and gamma-ray energies, quantum numbers, lifetimes, gamma-ray intensities, and other nuclear properties are recommended. Inconsistencies and discrepancies that exist in the literature are noted. This work supersedes the earlier evaluation by D. De Frenne and E. Jacobs (1996De55), published in Nuclear Data Sheets 79, 639 (1996).

The neutron-rich dysprosium isotopes ¹⁶⁸Dy₁₀₂ and ¹⁶⁹Dy₁₀₃ have been investigated using the EURICA γ-ray spectrometer, following production via in-flight fission of a high-intensity uranium beam in conjunction with isotope separation through the BigRIPS separator at RIBF in RIKEN Nishina Center. For ¹⁶⁸Dy, a previously unreported isomer with a half-life of 0.57(7) μs has been identified at an excitation energy of 1378 keV, and its presence affirmed independently using γ-γ-γ coincidence data taken with Gammasphere via two-proton transfer from an enriched ¹⁷⁰Er target performed at Argonne National Laboratory. This isomer is assigned Jπ = Kπ = (4⁻) based on the measured transition strengths, decay patterns, and the energy systematics for two-quasiparticle states in N = 102 isotones. The underlying mechanism of two-quasiparticle excitations in the doubly midshell region is discussed in comparison with the deformed QRPA and multi-quasiparticle calculations. In ¹⁶⁹Dy, the B(E2) value for the transition de-exciting the previously unreported Kπ = (1/2⁻) isomeric state at 166 keV to the Kπ = (5/2⁻) ground state is approximately two orders of magnitude larger than the E2 strength for the corresponding isomeric-decay transition in the N = 103 isotone ¹⁷³Yb, suggesting the presence of a significant γ-vibrational admixture with a dominant neutron one-quasiparticle component in the isomeric state.

γ-Ray emission probabilities from the decay of the long-lived (T(1/2)=160.44d) isomeric state in (177m)Lu were measured with planar (LEPS) and coaxial Ge detectors. The isomer γ-ray and β(-)-decay branching intensities were also determined. Measurements were carried out at low absolute efficiencies in order to minimize coincidence summing losses. The results are compared with the previous measurements.

Evaluated nuclear structure and decay data for all nuclei within the A=207 mass chain are presented. The experimental data are evaluated and best values for level and gamma-ray energies, quantum numbers, lifetimes, gamma-ray intensities, and other nuclear properties are recommended. Inconsistencies and discrepancies that exist in the literature are noted. This work supersedes the earlier evaluation by M.J. Martin (1993Ma73), published in Nuclear Data Sheets 70, 315 (1993).

The full-energy peak efficiency calibration and the energy resolution measurements of the 2 in . × 2 in . LaBr 3 γ -ray detector are presented for γ -ray energies in the 700 keV–17.6 MeV range. Measurements were done using a combination of proton-capture nuclear reactions on Al 27 , Na 23 , K 39 , Li 7 and B 11 for high-energy γ -rays, and radioactive sources such as Co 60 and Eu 152 for the lowest energies. At high energies, two γ -rays in a cascade from proton resonance capture were employed using Al, Na 2 WO 4 , K 2 SO 4 and LiBO 2 targets. The obtained results were compared to the simulations performed using a GEANT4 code.

The neutron-rich N = 126 nucleus Au-205 has been populated following the relativistic energy projectile fragmentation of E/A = 1 GeV Pb-208, and studied via charged-particle decay spectroscopy. An internal decay with a transition energy of 907(5) keV and a half-life of T-1/2 = 6(2) s has been identified through the observation of the corresponding K and L internal conversion electron lines. The 907 keV energy level corresponds to the pi h(11/2)(-1) proton-hole state and decays both internally into the pi d(3/2)(-1) ground-state and via beta decay into Hg-205. The obtained data provides information on the evolution of single-proton hole energies which are vital inputs of shell model descriptions for nuclei around the Pb-208(82)126 doubly magic core. (C) 2009 Elsevier B.V. All rights reserved.

Evaluated nuclear structure and decay data for all nuclei within the A = 200 mass chain are presented. This work supersedes the earlier evaluation by M.R. Schmorak (1995Sc23), published in Nuclear Data Sheets 75, 667 (1995). The electron conversion coefficients used in the present evaluation are from 2005KiZW.

The performance of new scintillator detectors based on LaBr{sub 3}(Ce) technology was evaluated in conjunction with the Gammasphere spectrometer. Specifically, the lifetimes of states between 50 ps and 1 ns, populated in the decay of the {sup 177m}Lu isomeric state (T{sub 1/2} = 160 d), have been measured. Even though the decay scheme is rather complex, it is possible to perform precise measurements because of the superior energy resolution of the LaBr{sub 3}(Ce) detectors, compared to that of BaF{sub 2} scintillators, when used in combination with the power of the Gammasphere array to isolate a specific {gamma} cascade

Erratum Erratum to: “Neutron–proton pairing competition in N = Z nuclei: Metastable state decays in the proton dripline nuclei 82 41Nb and 86 43Tc” [Phys. Lett. B 660 (2008) 326] A.B. Garnsworthy a,b,∗, P.H. Regan a, L. Caceres c,d, S. Pietri a, Y. Sun e,f, D. Rudolph g, M. Gorska c, Zs. Podolyak a, S.J. Steer a, R. Hoischen g,c, A. Heinz b, F. Becker c, P. Bednarczyk c,h, P. Doornenbal c, H. Geissel c, J. Gerl c, H. Grawe c, J. Grȩbosz h,c, A. Kelic c, I. Kojouharov c, N. Kurz c, F. Montes c, W. Prokopowicz c, T. Saito c, H. Schaffner c, S. Tachenov c, E. Werner-Malento c,i, H.J. Wollersheim c, G. Benzoni j, B.B. Blank k, C. Brandau a,c, A.M. Bruce l, F. Camera j, W.N. Catford a, I.J. Cullen a, Zs. Dombradim, E. Estevez n, W. Gelletly a, G. Ilie o,p, J. Jolie o, G.A. Jones a, A. Jungclaus d, M. Kmiecik h, F.G. Kondev q, T. Kurtukian-Nieto n,k, S. Lalkovski l,r, Z. Liu a, A. Maj h, S. Myalski h, M. Pfutzner i, S. Schwertel s, T. Shizuma a,t, A.J. Simons u,a, P.M. Walker a, O. Wieland j, F.R. Xu v