Experimental study of the decay of81gSe and81mSe

The decay of^81gSe and^81mSe was investigated with Ge(Li) spectrometers and Ge(Li) gamma-gamma coincidences. Accurate energies, intensities and half-lives have been measured for 11 gamma-rays. These gamma-rays fit into a⁸¹Br level scheme with levels at: 275.9, 535.9, 538.2, 565.9, 649.7 and 828.2 keV. Beta component intensities were deduced from measured gamma intensities. The half-life is found to be (17.9±0.5) min for^81gSe, and (57.28±0.05) min for^81mSe.     

The decay of75Ga to levels in75Ge

The decay of⁷⁵Ga has been investigated with Ge(Li) spectrometers. Energy and intensity determinations for 37 gamma rays have been performed. A level scheme for⁷⁵Ge was deduced, where 31 gamma transitions could be placed. Beta branch intensities were estimated from the measured gamma intensities. Spin and parity assignments for most of the levels were made in agreement with reaction and neutron capture studies. Half life of⁷⁵Ga was measured to be (130±6) sec and that of the 139.3 keV isomeric state in⁷⁵Ge to be (47.7±0.5) sec.     

Experimental study of the decay of147Pr to levels in147Nd

The decay of¹⁴⁷Pr produced by (γ, p) reaction on enriched¹⁴⁸Nd has been studied with Ge(Li) detectors and gamma-gamma coincidence methods. Half-life determinations, and accurate energy and intensity measurements for 84 gamma transitions have been performed. A level scheme with 21 levels including 62 of the transitions was deduced. Beta branch intensities were estimated from measured gamma intensities. Tentative spin and parity assignments are given.     

The levels of144Pr from the decay of144Ce

The level scheme of¹⁴⁴Pr has been studied from the decay of¹⁴⁴Ce. The intensities and energies of gamma rays have been determined with a X-ray Ge(Li) detector. TheK-shell internal conversion coefficients for γ-rays have been measured with theK X-ray/γ-ray ratio method using NaI(Tl)—X-ray Ge(Li) coincidence techniques.     

The decay of140Pr to levels in140Ce

The decay of¹⁴⁰Pr was investigated by means of a Ge(Li) spectrometer. Excited states of¹⁴⁰Ce at 1,596.2, 1,903.1, 2,348.9, 2,522.5, 3,016.8 and 3,119.6 keV are fed in the beta decay of¹⁴⁰Pr. Spin and parity assignments for all observed levels have been made from electron capture and positon disintegration considerations and gamma branches. The experimental level scheme of¹⁴⁰Ce is compared with the results of shell model calculations forN=82 nuclei.     

The decay of110mAg to110Cd

The gamma-ray spectrum of the decay of^110mAg has been measured with the Ge(Li) detectors. A total of 32 gamma rays associated with the decay of^110mAg have been observed and their intensities determined. A number of gamma-ray transitions have not been observed previously. The K-electron internal conversion coefficients were found from the relative gamma intensities used in conjunction with published K-conversion electron intensities.It is proposed that the level scheme of¹¹⁰Cd has new levels at 1410·4, 1443·2 and 2237·7 keV in addition to the previously known levels. The spins and parities of the new levels are discussed.The author wishes to express her gratitude to Professor V. Petrílka for his permanent support and to Mr. J. Lipták and Mr. J. Vrzal for valuable assistance and discussions.     

In-beam gamma-ray and electron spectroscopy following the75As(p,n)75Se reaction

The level scheme of⁷⁵Se has been studied through the⁷⁵As (p, n) reaction at proton energies from 1.5 to 5.0 MeV.γ-ray and internal conversion electron measurements were made using NaI (T1) and Ge(Li) detectors and a six-gap electron spectrometer. A proportional counter and a thin window NaI(T1) detector were used to detectγ-rays with energies less than 30 keV. The level scheme has been established by observing the thresholds of variousγ-rays and byγ-γ and e^?-γ coincidence measurements. New levels at 133.0, 293.2, 790.0, 953.0, 1020.8, 1184.3, 1198.5 and 1258.2 keV not observed in earlier (p, n) studies have been established. Conversion coefficients of most of the low-lying transitions have been determined. Angular distributions of some of theγ-rays were also measured and compared with the statistical model calculations. DefiniteJ ^π assignments have been made to most of the low-lying levels. Life-times of the 112.1, 133.0, 286.7 and 293.2 keV levels have been measured to be 0.69±0.12, 5.3±0.6, 1.35±0.15 and 31±2 nsec respectively. The reduced transition probabilities for various low-lying transitions have been determined and compared with recent calculations. The 1/2^? and 9/2⁺ levels hitherto unknown in this nucleus has been identified. The structure of the low-lying levels is discussed in terms of the existing models.     

The decay of85As

The decay of isotope-separated⁸⁵As has been studied for the first time by means ofγ-ray spectroscopy. A level scheme for⁸⁵Se has been constructed on the basis ofγγ-coincidence measurements. Spin and parity were then assigned to the lowest excited levels. Two levels, weakly populated in⁸⁴Se after emission of delayed neutrons, were also identified. The results obtained here differ considerably from previously reported experiments with chemically separated sources.     

Beta decay of22O

The beta-gamma spectroscopic study of²²O is presented. This nucleus, produced as a projectile-like fragment from the interaction of a 60 MeV/n⁴⁰Ar beam with a Be target, has been separated by the LISE spectrometer. Several gamma rays from²²O decay have been observed, from which a half-life of (2.25±0.15)s has been determined. Accurate excitation energies have been deduced for several states in²²F. A partial beta decay scheme of²²O has been established. Experimental results have been compared with shell model calculations.     

Intensitätsmessung von Röntgen- und Kerngammastrahlung an einigen schweren Myonenatomen

Absolute intensities of the 5–4 muonic X-ray transition in muonic W, Os, and Bi, and relative intensities of other X-ray transitions have been measured and compared with cascade calculations. The excitation of several levels in W, Os, Ir, Tl, and Bi nuclei resulting from the muonic cascade process has been observed and absolute excitation probabilities have been determined. For the first 2⁺ level of¹⁸⁸Os and the first 3/2⁺-levels of^203,205Tl the excitation probabilities are larger than calculated. The results are discussed.     

Internal conversion studies of transitions in96Mo

The internal conversion spectrum from the decay of⁹⁶Tc has been investigated using a 50 cm radius double-focussing beta-ray spectrometer. Relevant features of the internal conversion spectrum from the decay of⁹⁶Nb have also been reexamined in the same way. Special interest has been focussed on investigating a proposed doublet level structure at about 2.44 MeV and higher lying levels in⁹⁶Mo. Internal conversion coefficients have been obtained for most transitions by combining the measured conversion electron intensities obtained in this work with recently reported gamma-ray intensities from Ge(Li) detector measurements. A level scheme has been compiled and deduced transition multipolarities have been used for a discussion of spins and parities for the levels.     

The decay of143Sm to levels in143Pm

The beta decay of¹⁴³Sm was reinvestigated with the aid of a Ge(Li) detector. Levels of¹⁴³Pm at 271.8, 1,056.5, 1,173.4, 1,342.1, 1,403.2, 1,514.9, 1,752.8, 1,816.3, 1,853.6, (2,000), 2,009.0, 2,080.5, 2,344, 2,443, 2,463, 2,906 and (3,054) keV were established. Logft values for all observed beta transitions have been calculated. Spin and parity assignments have been made from electron capture and positon disintegration considerations and gamma branches. The experimental level scheme of¹⁴³Pm is compared with the results of 1 and 3 q.p. calculations forN=82 nuclei.     

The decay of63Zn

Energies and relative intensities ofγ-ray transitions in the decay of⁶³Zn have been measured with a Ge(Li) spectrometer in an anti-Compton anti-annihilation set up. Gamma-gamma coincidences and the “energy level spectrum” have been measured. Some aspects of the resulting decay scheme are compared with existing theoretical predictions.     

The β decay of tellurium 135 and 137

Tellerium 135 and 137 nuclei were produced in thermal neutron fission of²³⁵U separated by on-line isotope separator and deposited on a movable tape. Gamma ray singles,γ-γ, β-γ coincidences and time sequencedγ spectra were collected using Ge(Li) detectors and scintillator (NE 102 A) telescope. The half-lives and mass excesses of¹³⁵Te and¹³⁷Te were measured and level schemes of¹³⁵I and¹³⁵I have been established. The level scheme of¹³⁵I has been compared to different shell model calculations.     

The decay of65Ge

Energies and relative intensities of γ-rays from the decay of⁶⁵Ge have been measured. The half-life was measured to be (31.2±0.7) sec. From the measured intensity of the annihilition radiation the intensity of the groundstate ß⁺ feeding was determined to be <10%. A total of 31 γ transitions was placed in a level scheme. The spin and parity of the groundstate of⁶⁵Ge was determined to be 3/2^? (5/2^?).     

Deformations and shape changes in81Y

High spin states in⁸¹Y up to the probable 33/2⁺ and 29/2^? yrast states have been measured via the reaction⁵⁸Ni(²⁸Si,αp, using the Cologne tandem accelerator. Directional correlations of oriented nuclei were determined and the level scheme was extended with lifetimes measured by means of DSA and recoil distance techniques. Reduced transition strengths inferred from lifetimes were consistent with the results of Hartree-Fock-Bogolyubov calculations, which predict a nearly axially symmetric deformation ofβ ₂≈0.37 for theπ=+ band. Predictions reveal an alignment driving the system to a smaller and triaxial deformation withβ ₂=0.23 andγ=?30°, although the data show this crossing to be somewhat delayed. Particle-rotor calculations for the one-quasiparticle bands corroborate the predictions of deformation parameters based on the cranking model.     

Messung von HalbwertszeitenK-verbotener Übergänge ingg-Kernen der Seltenen Erden

The half-life of the 1,490 keV level in¹⁶²Dy has been measured in the decay of¹⁶²Ho^m (68 min) by delayed coincidences ofKX rays and (900-1,300) keV gamma radiation to be (1.94 ± 0.19) nsec. A half-life in¹⁷⁶Hf has been remeasured in the decay of¹⁷⁶Ta (8.1h) by delayed coincidences of KX rays and (1,100–1,200) keV gamma radiation to be (4.75 ± 0.25) nsec. In order to fix the level with this half-life in the level scheme of¹⁷⁶Hf, the gamma spectrum delayed to KX rays was measured. It is suggested that probably the 1,227.4 keV-level of¹⁷⁶Hf is delayed and has the spin 2^? or 3⁺.     

Decay of97Zr to nuclear states of97Nb

The gamma rays emitted in disintegration of⁹⁷Zr have been investigated by Ge(Li) detectors, operated singly and in coincidence. In all, quanta emitted in thirty-five nuclear transitions have been observed. The gamma ray energies and relative intensities have been measured. Beta spectra have been studied with Ge(Li) detector and anthracene counter in coincidence. Nine beta spectra have been identified as to end point and intensity, either by direct measurement or by inference from the gamma ray data. The results of all measurements have been combined to provide a decay scheme for⁹⁷Zr. Nuclear excited states in⁹⁷Nb are indicated at energies of 743, 1,148, 1,251, 1,276, 1,434, 1,548, 1,652, 1,750, 1,765, 1,852, 1,958, 2,056, 2,106, and 2,247 keV. Possible spin-parity assignments have been suggested for some of these states.     

High spin states in144Sm

High spin states of¹⁴⁴Sm have been investigated via the¹²⁶Te(²⁴Mg,4n) reaction at 98 MeV with in-beam- ray spectroscopy using the Compton-suppressed germanium detector array OSIRIS-CUBE. 44 new levels and 82 new transitions have been placed in the level scheme. Spins up to J=18 were assigned from gamma angular distribution data and parities were determined from gamma linear polarization data obtained using the POLALI spectrometer. The experimentally observed excitation energies of negative parity states could be well reproduced by shell model calculations.     

High spin states in the transitional nucleus88Mo

The reaction⁵⁸Ni(³⁶Ar,α qρ)⁸⁸Mo has been studied at 145 MeV beam energy. A detector array consisting of the OSIRIS spectrometer, four charged-particleΔE detectors and seven NE213 neutron detectors has been used to meaure the gamma radiation inγγ- and particle-γγ-coincidence mode. The level scheme of⁸⁸Mo has been extended up to 11.6 MeV excitation energy and probable spin 23?; some 70 transitions and 40 levels have been identified. Spin assignments have been proposed on the basis of measured DCO ratios. Hartree Fock cranking calculations of the Total Routhians and shell model calculations of the high spin states are presented which imply near-sphericity of the yrast line up to the highest spins found. A classification of the high spin states according to their leading seniority is proposed.