Levels of118Sn populated in the decay of118In and118Sb isomers

Gamma-rays in the disintegration of 5.0 s (1⁺), 8.5 s (7^?, 8^?), and 4.4 min (4⁺, 5⁺)¹¹⁸In isomers and of 3.5 min (1⁺) and 5.1 h (8^?)¹¹⁸Sb isomers have been investigated using Ge(Li) detectors and Ge(Li)-NaI(Tl) coincidence spectrometers. The decay schemes of these isomers have been constructed incorporating 17 levels in the product nucleus,¹¹⁸Sn, at the following energies (in keV): 0 (0⁺), 1229.5 (2⁺), 1757.5 (0⁺), 2043.1 (2⁺), 2056.4 (0⁺), 2280.3 (4⁺), 2321.3 (5^?), 2326.4 (1⁺, 2⁺), 2402.7 (4⁺), 2488.8 (4⁺), 2496.5 (0⁺), 2575.2 (7^?), 2677.3, 2733.7 (2⁺), 2929.8, 2963.5 (4⁺), and 3137.1 (0⁺). The structure of¹¹⁸Sn is briefly discussed in view of results from recent quasiparticle-model calculations.     

Levels in189Os populated in the decay of189Re

The excited level scheme of¹⁸⁹Os as populated by the decay of 23.4-h¹⁸⁹Re has been studied by use of Ge(Li) and Si(Li) detectors in the γ-ray singles and coincidence mode. The data confirm the presence of excited levels in¹⁸⁹Os at 30.8 (J ^π=9/2^?), 36.2 (1/2^?), 69.5 (5/2^?), 95.2 (3/2^?), 216.7 (7/2^?), 219.4 (7/2^?), 233.6 (3/2^?), 275.8 (5/2^?), 496.8 (1/2^?, 3/2⁺) and 599.8 (1/2^?, 3/2⁺) keV. The spin and parity assignments are based on multipolarities determined by internal conversion coefficient measurements and decay systematics. A decay scheme is established for¹⁸⁹Re which accommodates 98% of the electromagnetic transition intensity. No evidence for the 150-d¹⁸⁹Re isomer was found in this study.     

Levels in182W populated in the decay of182Ta

Theγ-rays emitted in theβ-decay of¹⁸²Ta have been reinvestigated with improved statistics in attempting to clarify the reported new levels at 1460.41, 1592.98, 1620.36, 1712.29 and 1762.91 keV in¹⁸²W observed in theβ-decay of¹⁸²Ta. The present study demonstrated that the fifteen newγ-rays, which were used to support the existence of the five new levels, are not relevant to theγ-decay of¹⁸²Ta. Therefore the five new levels are not populated in this decay. Additionally, theγ-ray with an energy of 1035.6 keV (0 ₂ ⁺ →2 ₁ ⁺ ) deexciting theβ-band head in¹⁸²W is observed for the first time in the present decay study and the previous tentative placement of the 351.0 keVγ-ray in the level scheme is confirmed by the present coincidence measurements.     

Levels in159Ho as populated from decay of159Er

The level scheme of the odd proton nucleus¹⁵⁹Ho has been investigated using Ge(Li) and Si(Li) detectors. Results ofγ-ray singles, conversion electron spectra and coincidence experiments are reported. Assignments are made for several energy levels.     

Beta decay of 125Sb and level structures in 125Te

The decay of 2.76y ¹²⁵Sb to levels of ¹²⁵Te has been studied using an HPGe detector for gamma-ray and a mini orange electron spectrometer for conversion electron measurements. We identify 38 transitions in this decay, including 13 gamma rays and 4 conversion electron lines being reported for the first time. New results also include E1 multipolarity assignments to 3 newly observed transitions and M-shell conversion coefficient for the 109 keV M4 transition. A revised ¹²⁵Te level scheme is constructed using Ritz combination principle. While confirming the existence of 10 well established levels below 700 keV excitation, we introduce 3 other levels at 402.0, 538.6 and 652.9 keV. Interpretation of the observed levels in terms of various theoretical approaches is briefly discussed. The newly introduced 538.6 keV (1/2⁺) and 652.9 keV (3/2⁺) levels are seen as the two missing members of the (s _1/2 ⊗ 2⁺) and (d _3/2 ⊗ 2⁺) sextuplet in the quasiparticle-phonon coupling scheme.     

Levels in208Pb populated in the decay of208Tl(ThC″)

Gamma rays in the disintegration of²⁰⁸Tl(ThC″) have been studied with Ge(Li)-Na I(Tl) anti-Compton and coincidence spectrometers. Several new transitions are reported most of which are placed in a decay scheme incorporating excited states in²⁰⁸Pb at 2,614.5, 3,197.6, 3,475.0, 3,708.3, 3,919.8, 3,960.9, 3,998.5, 4,125.3, 4,180.4, 4,296.1 and 4,480.0 keV. According to the present data, the recently reported intensity of 4.5±1.5% of beta groups feeding levels near 4.3 MeV is far too large.     

Levels in152Gd and152Sm populated by the decay of152Eu

The energy level schemes of¹⁵²Gd and¹⁵²Sm have been established on the basis of singlesγ-spectra, andγ- γ coincidence measurements. Ge(Li) detectors were used to study the gamma spectra produced in the EC/β⁺ and β^? decays of¹⁵²Eu to¹⁵²Sm and¹⁵²Gd, respectively. Thirteen new transitions are reported and data from eleven coincidence gates enabled five new levels to be suggested. Relative intensities and logf t values were calculated and spin/parities deduced. Comparisons are made with new predictions of the Interacting Boson Model.     

Levels and transition probabilities in 124In as observed in the decay of 124Cd

The levels of ¹²⁴In, which are populated in the decay of ¹²⁴Cd, have been investigated at the OSIRIS on-line facility by means of conversion electron and γ-ray spectroscopy. A γ-γ coincidence measurement combined with the deduced transition intensities permitted construction of a unique level scheme. The half-life of the 243 keV level of ¹²⁴In has been determined to be 50 ± 6 ns by the method of delayed coincidences.     

Low lying levels in124Sb

The level structure of¹²⁴Sb is investigated through the¹²⁴Sn(p, nγ-γ)¹²⁴Sb reactions using on-lineγ- γ coincidence techniques. A total of 13 levels in¹²⁴Sb below 600 keV excitation are identified. In addition some conclusions regarding spins and parities are made for some of these levels, based on the transitions observed in this work and comparisons with previous data.     

166Er levels populated in the166Tm decay

The decay of¹⁶⁶Tm has been investigated with samples obtained by chemical extraction and mass-separation from spallation products of tantalum irradiated with 660 MeV protons. Measurements of gamma rays, - bi-dimensional coincidences, CE- coincidences and internal conversion electrons have been performed. About 300 -transitions have been observed; most of them are placed in a level scheme of¹⁶⁶Er. The properties of some rotational and vibrational bands and of some other levels are discussed.The authors express their thanks to A. V.Zolotavin for his extended discussions on different aspects of the¹⁶⁶Tm decay, N. A.Lebedev, I. I.Gromova for the preparation of the targets and to co-workers of refs. [4, 5, 14, 15 and 16], who participated in this work at different stages.     

Low energy nuclear states in124Te

The energy level scheme of¹²⁴Te has been established on the basis of singlesγ-spectra, andγ-γ coincidence measurements carried out using a dual parameter data collection system. Ge(Li) detectors were used to study the gamma spectra produced in theβ ^? decay of¹²⁴Sb. Eleven new transitions and two new energy levels are proposed. Relative intensities, branching ratios,α(K) and logft values were calculated and multipolarities, spins and parities deduced. Comparisons are made with predictions of the Interacting Boson Model: in a first order perturbation approximation to theSU (5) limit, using the complete IBA-1 Hamiltonian, and in theO(6) limit.     

Energy levels of Kr populated by Br decay

The γ-rays following the β-decay of ⁸²Br have been investigated using a 220 mm³ Ge(Li) detector, an anti-Compton NaI(Tl) spectrometer and a two-dimensional coincidence arrangement. The ⁸²Br was produced by thermal neutron activation of ammonium bromide. The presence of eight, well-known and 11 weak γ-rays has been established. It has been shown through half-life measurements that the newly identified γ-rays belong to ⁸²Br decay and that the high-energy peaks are not to summing effects. All the reported transitions have been incorporated in a level scheme of ⁸²Kr by introducing levels at 0, 776, 1474, 1820, 1953, 2093, 2426, 2554, 2647 and 2828 keV. Limits on probable spin and parity values for the newly-introduced levels have been established. The level introduced at 2828 keV on the basis of a 1008–1043 keV γγ-coincidence must be fed by a weak β-branch of ⁸²Br with an end-point energy of 263 keV and log ft of approximately 6.1.     

Search for weakly populated states in the decay of51Cr

A low level counting facility equipped with two large Na I(Tl) detectors was used to search for previously reported transitions of 470 and 640 keV in the decay of⁵¹Cr. Our results yield upper limits of 1.4× 10^?6 and 0.95× 10^?6 transitions/decay for these two transitions, respectively. These limits are now so low as to indicate these levels do not exist in⁵¹V.     

Nuclear levels in228Th populated in the decay of228Pa

The electron-capture decay of²²⁸Pa to levels in²²⁸Th has been studied using mass-separated sources and high-resolutionγ-ray and conversion-electron spectroscopy. A level at 979.5 keV is assigned as 2⁺ member of a second excited K_π=0⁺ band, with the 0⁺ band head at 938.6 keV. The 2⁺ and 3⁺ members of a second excited K_π=2⁺ band at 1153.5 and 1200.5 keV, which decay by strongE0 transitions to the 969 keVγ-vibrational band, are confirmed. In addition we tentatively propose a K_π=1⁺ band at 944 keV. The K_π=0^?, 1^? and 2^? members of the octupole quadruplet are confirmed, and theγ decay of these levels is analysed in an approach, in which the mixing of the octupole bands by the Coriolis interaction is taken into account. It is suggested that octupole correlations might be important for theE1 transition moments. A total of 29 levels is observed between ～1.4 and ～2.0 MeV, for which the nuclear structure, and the possible assignment to rotational bands, is unclear.     

Energy levels of174Yb populated in the decay of174Tm

The decay of the¹⁷⁴Tm activity has been studied with Ge(Li) detectors and with a Ge(Li)—NaI(Tl) coincidence arrangement. Gamma ray energies and relative intensities were determined. Five new gamma transitions are reported, four of which have been placed in the decay scheme in addition to the previously observed but unplaced 1305 keV transition. Five energy levels at 1557.7, 1762.1, 1781.1, 1877.5 and 2050.1 keV not earlier reported to be populated in the decay of¹⁷⁴Tm are suggested. Some spin and parity assignments are proposed and the intrinsic structure of several states is discussed in terms of two quasi-particle excitations. For the half-life of¹⁷⁴Tm a value 5.4±0.1 min was measured.     

Superconductivity of A1-type SnSb,SbTe and TeI alloys

Superconducting A1-type Sn, SnSb, Sb, SbTe, Te, Te I and I films were vapour-quenched on glass substrates quench-coated with CaO. The highest transition temperature is exhibited by 100 Å thick 20Sn–80Sb films, which become superconducting at 21.6 K.     

States inN=80140Nd populated in the decay of140Pm

The level structure of theN=80,¹⁴⁰Nd has been investigated through the beta decay of^140m Pm and^140g Pm, whose decay half-lives were measured to be 5.95±0.05 min and 9.1±0.5 sec, respectively. Decay schemes for the two isomers have been constructed fromγ-ray measurements. With the help of the beta decayft values and internal conversion electron measurements, spins and parities were deduced for levels in¹⁴⁰Nd. Among the levels a 7^? state at 2222.0 keV and a 5^? state at 2273.3 keV are identified as two-neutron quasiparticle states. The (ie233-01) for^140m Pm and^140g Pm have been deduced as 7^? and 1⁺, respectively. From beta end-point measurements, the decay energies of the two isomers have been determined asQ _EC=6.48±0.07 MeV^140m (Pm) andQ _EC=6.08±0.10 MeV (^140gPm). The results are discussed in the light of nuclear systematics of theN=79 and 80 isotones.     

States inN=79142Eu populated in the decay of142Gd

The structure of¹⁴²Eu is investigated through the beta decay of¹⁴²Gd, whose decay half-life is measured to be (69.1±1.0) s. A level scheme comprising 42 transitions depopulating 18 excited states is constructed. With the help of the deduced ft values and measured internal conversion coefficients, spin-parity assignments are proposed for several states in¹⁴²Eu. The level systematics of the doubly odd,N=79 isotones are discussed.