Investigation of levels in59Ni following the β+ decay of59Cu

82s⁵⁹Cu was produced by the⁵⁸Ni(p, γ)⁵⁹Cu reaction using enriched target. The γ-ray spectra following the gb⁺ decay of⁵⁹Cu were studied using two 65 cm³ and 55 cm³ Ge(Li) detectors. Besides confirming all the previously known γ-rays from⁵⁹Cu decay, new γ-rays have been observed and additional direct β⁺ branches to the 1778.8 and 1950keV states of⁵⁹Ni have been identified with estimated log/tft values of 5.6 and 6.7 respectively. Validity of some of the controversial levels around 1700 keV is discussed. The weak γ-ray branches from levels upto 1679.7 keV are compared and found to be in fair agreement with the theoretical predictions of Glaudemans et al.     

Gamma decay of93Mo states from92Mo (d,pγ) and93Tc β-decay

The decay scheme of the fragmented single neutron states of93Mo up to 3.2 MeV excitation energy is obtained from a⁹²Mo(d,pγ)⁹³Mo coincidence experiment. The total γ-spectrum from⁹²Mo+d shows additional strong γ-decays following the β-decay of⁹³Tc produced by the (d, n) reaction. The decay scheme is discussed in the frame of the particle-core coupling model. The important role of 2⁺ core excited components inE2 andM1 transitions between states with different angular momentum of the single particle component is pointed out.     

Investigation of dual decay of70Ga (21 min)

The weakβ ^?-branchings in⁷⁰Ga decay leading to excited states in⁷⁰Ge at 1039 keV, and 1215 keV were measured byβ ^?-ray and γ-ray detection in 4π geometry to be 0.36 ±0.02%, and 0.32±0.01%, respectively. The weak electron capture decay of⁷⁰Ga was confirmed and its intensity measured to be 0.41±0.05%. The energy of the γ-rays was remeasured to be 176.17±0.02 keV, and 1039.20±0.08 keV.     

The level scheme of91Nb from the reaction90Zr (p, γ)91Nb

The level scheme of⁹¹Nb has been investigated with the reaction⁹⁰Zr(p, γ)⁹¹Nb. Proton energies between 3.0 and 7.2 MeV were used. The γ spectra were taken with Ge(Li) detectors. Primary γ transitions to 36 excited states of⁹¹Nb up to 3.8 MeV excitation energy and many secondary γ transitions from the decay of those states were observed, leading to an extension of the known level scheme. The proton binding energy for⁹¹Nb was determined as (5167± 5) keV. Eleven γ transitions in⁹⁰Zr, part of them new, from the competing reaction⁹⁰Zr(p, p′ γ) were also observed.     

The decay schemes of Y and Y and γ-rays observed in the decay of Y

Active yttrium was separated from ²³⁵U fission products and the decay of ⁹⁴Y, ⁹⁵Y and ⁹⁶Y to the levels of ⁹⁴Zr, ⁹⁵Zr and ⁹⁶Zr, respectively, has been studied with the aid of a 17 cm³ Ge(Li) detector. Gamma-ray energies and intensities were accurately determined. In the decay of ⁹⁴Y four new transitions at 1232.78 ± 0.35, 1324.97 ± 0.35, 1363.48 ± 0.35 and 2467.00 ± 2.75 keV were observed. The data obtained support the level scheme proposed for ⁹⁴Zr by Knight et al. and that deduced from more recent reaction data. Evidence supporting the location of the 0⁺ excited state at 1300 keV is presented. Branching ratios are calculated and a modified level scheme for ⁹⁴Zr is proposed. In the decay of ⁹⁵Y the energies of 13 γ-rays, previously identified with the decay of this nuclide, have been accurately measured and are presented in a partial level scheme for ⁹⁵Zr. The data obtained in this work support the level structure deduced from reaction data by Cohen and Chubinsky and by other workers. New γ-transitions at 550.10 ± 0.23, 1723.30 ± 0.90 and 1805.0 ± 1.0 keV were measured in the decay of ⁹⁶Y.     

Properties of electromagnetic transitions from high-spin states in94Mo

The multipole mixing ratios of transitions from 6⁺ and 8⁺ states in⁹⁴Mo, following the decay of⁹⁴Tc, have been measured by means ofγγ angular correlations. The spin of the 2423.4 keV state, being important for the interpretation ofγ cascades feeding this level, has been firmly established as 6⁺ by a method in which the angular correlation data are utilized in a non-conventional way. Furthermore, properties of electromagnetic transitions in⁹⁴Mo have been calculated in the shell model framework and are compared with the corresponding experimental quantities.     

Study of159Yb decay

Theβ ⁺-decay of 1.4 min¹⁵⁹Yb was studied at the YAS-NAPP-2 facility installed on the proton beam of the JINR Dubna phasotron. The singles γ-ray spectra and prompt and delayedγ-γ coincidences were measured on the multidetector system. The decay scheme of¹⁵⁹Yb was proposed on the basis of theγ-γ coincidence data. The low lying states of¹⁵⁹Tm were preliminary identified within the framework of the rotational model.     

Single-step link of the superdeformed band in143Eu

²⁰⁹Fr has been produced by irradiation of¹⁹⁷Au with¹⁶O,and studied using a He-jet recoil tape transport system.A decay scheme is proposed for the first time,based on X-γ and γ-γ coincidence measurements,which takes account of 20 observed γ-rays. The branching ratio for (EC+β ⁺) decay of²⁰⁹Fr has been estimated to be 3.0±1.5%. Five members of low-lying states in²⁰⁹Rn can be explained with the configuration [(²¹⁰Rn 2⁺)(νf5/2)^?1].     

Désintégration de 88Y

Radioactive decay of ⁸⁸Y has been reinvestigated using coaxial Ge(Li) detectors. Energies and intensities of six γ-rays were measured. A new γ-ray of 850.6 keV was found showing that the 3584.7 keV level in ⁸⁸Sr is fed in this decay. The logft value for this level is consistent with a J^π = 4^?, 5^? assignment. A 3522 keV level reported elsewhere was not found.     

A study of excited states of5He by the7Li (d, α)5He-reaction

The interactions of deuterons with⁷Li, in which two α-particles and a neutron are produced in the final state are studied atE _d =1.2 MeV. The dual parameter α-α coincidence spectrum was analyzed with a search program. The results indicate two excited states of⁵He: One at excitation energy 2.9±0.1 MeV and with a reduced width of γ²=1.1±0.4 MeV, and the other at 4.8±0.4 MeV, with γ²=0.9±0.4 MeV. No contributions of sequential decay through the 4⁺ state in⁸Be or direct three body decay was observed.     

Der Zerfall des95Sr

The nuclide⁹⁵Sr was isolated by chemical separation methods after thermal neutron induced fission of²³⁵U. It's decay properties were investigated employing semiconductor spectrometers and coincidence techniques. A half-life of 24.4±0.2 sec was found. Out of 29 gamma rays, 25 transitions representing 97% of the observed gamma-ray intensity were placed in a decay scheme comprising 19 excited states of⁹⁵Y.     

Gamma-ray spectroscopy of87Y

The level structure of⁸⁷Y has been studied using in-beam γ-ray spectroscopic methods. Many previously unknown states have been observed. Members of theπ(g _9/2 )ν(g _9/2)^?2 multiplet are identified. The results are discussed in terms of the weak-coupling model.     

The decay of 26-s 94Rh and 71-s 94Rh isomers

The structure of⁹⁴Ru is investigated through the beta decay of two isomers of⁹⁴Rh, and whose half-lives are measured to be 25.8±0.2 s and 70.6±0.6 s respectively. The decay properties are studied by means of beta and gamma spectroscopy techniques. The level structure of⁹⁴Ru populated in the decays of both isomers is proposed with deducedJ ^π values. Theβ-decay energy for71-s ⁹⁴Rh is measured to be 10.0±0.4 MeV. The structure is discussed in terms of shell model.     

Radioactive decay of 1.7-h149Nd to levels of transitional149Pm

Sources of¹⁴⁹Nd were produced by thermal-neutron irradiation of enriched¹⁴⁸Nd. High resolution Ge(Li) spectrometers were used to collect gamma-ray singles and coincidence spectra in the study of the decay of 1.7-h¹⁴⁹Nd. A total of 214 gamma rays have been assigned to the decay of¹⁴⁹Nd, and 201 of these transitions have been placed in a level scheme of¹⁴⁹Pm involving 42 excited states. Absolute values for the beta-group intensities were determined for transitions to the¹⁴⁹Pm levels, and spin and parity assignments were made for many of the observed states. The experimentally determined level structure of¹⁴⁹Pm was compared with corresponding levels in other odd-mass Pm and Eu nuclides. Interpretations were made in terms of the core-coupling model. Radioactive decay¹⁴⁸Nd(n, γ)¹⁴⁹Nd; measuredE _γ,I _γ,γ-γ coinc.¹⁴⁹Pm deduced levels,J,π. Compton-suppression. Ge(Li) detector. Enriched targets.     

Structure of the neutron-rich nucleus 37 94 rb57

A level scheme has been established for ₃₇ ⁹⁴ Rb₅₇ based on studies at the fission-product separator JOSEF ofγγ coincidences following theβ- decay of⁹⁴Kr. For the 190.7 keV level a half-life of 2.5(8) ns has been determined through the centroid-shift method. The majorβ-decay branch of⁹⁴Kr proceeds with log ft=3.7 into the 988.4 keV state in⁹⁴Rb. This transition must be of the 0⁺→1⁺ GT type involving the transitionνg_7/2→πg_9/2. IBFFM calculations have been performed for⁹⁴Rb, starting from the parametrization used in the previous IBM investigations for the isotope⁹³Rb and the isotone⁹⁶Y. A theoretical interpretation of the low-lying levels including propositions for the spins is given in a comparison to the available data.     

High spin states of some nuclei around the N=Z=28 double closed shell

A spectroscopic study is performed for high spin states of⁵⁵Fe,⁵⁵Co and⁵⁷Ni. To populate the investigated residues with a relevant cross section, the fusion evaporation reactions of³⁰Si(²⁸Si, 2pn)⁵⁵Fe,³⁰Si(²⁸Si, 2np)⁵⁵Co and⁴He(⁵⁴Fe,n)⁵⁷Ni were chosen. To identify the newγ transitions and to build the energy level schemes,γ — γ coincidence techniques together with excitation functions were employed. Angular distributions andγ — γ angular correlations allowed us to assign the spin values of the nuclear states. The previous level scheme of⁵⁵Fe is extended into the region between 6.5–11 MeV of excitation energy, up to spin 27/2, while the yrast decay paths of⁵⁷Ni and⁵⁵Co are reported here for the first time. Experimental data are fairly well reproduced by Glaudemans' shell model calculations.     

Ion molecule collisions investigated via nuclear resonance fluorescence

The method of nuclear resonance fluorescence has been applied to analyse the profileN(E) of the 285 keV gamma line of⁷⁵As after electron capture decay of⁷⁵Se in gaseous⁷⁵SeH₂ sources. The profileN(E) depends on the velocity distribution of the radioactive As ions at the moment of γ-decay and, hence, is strongly dependent on the slowing down mechanism. Investigating sources with pressures of 1.5, 15, and 177 Torr different states of the slowing down process could be studied. A simple model is developed that describes the basic properties of the experimental line profiles.     

Electron capture decay of 51 min191Hg

The decay¹⁹¹Hg→¹⁹¹Au was investigated by measuring γ-ray spectra, conversion electron spectra, and coincidence spectra, as well as lifetimes in the second region. The parent isotope¹⁹¹Hg was produced by the reaction¹⁹⁷Au (d, 8n) withE _d =80 MeV. About 80 γ-transitions of this decay were observed. Multipolarities of the more intense transitions were determined. An isomeric state of 0.92±0.11 s half-life was found in¹⁹¹Au. A level scheme for¹⁹¹Au is suggested. The measured γ-transitions are attributed to the decay of a 13/2⁺ isomeric state of¹⁹¹Hg; its half-life was found to be 50.8 ±1.5 min. The core excitation model was used to discuss some features of the level structure in¹⁹¹Au.     

Nuclear spectroscopy of90Y

The level structure of⁹⁰Y has been studied using the⁹¹Zr(t,α)⁹⁰Y and⁸⁹Y(n,γ)⁹⁰Y reactions. The proton pickup reaction was studied with 17 MeV tritons and a Q3D spectrometer. In the thermal⁸⁹Y(n, γ)⁹⁰Y reactionγ-rays from ≈100 to 6,857 keV were observed. In addition to previously known states and configurations, the ten states of theπ(p 3/2)^?1 v(d 5/2)¹ andπ(f 5/2)^?1 v(d 5/2)¹ configurations are assigned. Also many other new levels are identified from the (n, γ) data. The 0?state of theπ(f 5/2)^?1 v(d 5/2)¹ is assigned at 3,130keV. Finite-range shell model calculations suggest that the tensor force is necessary to reproduce the experimentally observed splittings.     

Decay properties of139mSm and139Eu

The structure of¹³⁹Sm is investigated through the decay properties of^139mSm and¹³⁹Eu. The decay of^139mSm is measured to have a half-life of (10.7±0.6) s. Gamma-ray and internal conversion electron measurements lead to the construction of a decay pattern comprising seven transitions among five states. The decay of¹³⁹Eu with a measured half-life of (17.9± 0.6) s is studied with beta decay spectroscopy techniques. A decay scheme consisting fourteen states in¹³⁹Sm is proposed. Using deducedft values and transition multipolarities,J ^ρ assignments are made. Nuclear systematics of the odd-A, N=77 and 76 are discussed.