Precise atomic mass determinations at mass 124

The Manitoba II high-resolution mass spectrometer has been used to determine eight precise atomic mass differences amongst ¹²⁴Sn, ¹²⁴Te, ¹²⁴Xe, ¹³C³⁷Cl₃ and ⁵⁴Fe³⁵Cl₂. Precise values have been derived for the double β- decay energies of ¹²⁴Xe and ¹²⁴Sn and for the masses of ¹²⁴Sn, ¹²⁴Te, ¹²⁴Xe and ⁵⁴Fe. The precision of the mass of ¹²⁴Xe has been improved by a factor of ≈150.     

Levels in124Te populated in the decay of124Sb

The levels in¹²⁴Te have been investigated by studying the gamma rays emitted following the decay of 60d¹²⁴Sb. Gamma-gamma coincidence spectra have been taken with gates set at 603, 646, 709, 714 and 723 keV gamma rays by using 105 cm³ Ge(Li)-110 cm³ HPGe coincidence system. 69 gamma rays have been observed and nine of them are reported for the first time. Four new levels in¹²⁴Te at 2512, 2550.2, 2808 and 2814.5 keV are proposed. Levels reported in literatures at 2412 and 2733 keV are excluded from the level scheme of¹²⁴Te based on the present study. The experimentally determined energy spectrum of low-lying positive parity states, B(E2) ratios and electric quadrupole moment of the first excited state are compared with the IBM-1 predictions.     

Nuclear deformation and the two-neutrino double- β decay in <Superscript>124, 126</Superscript>Xe , <Superscript>128, 130</Superscript>Te , <Superscript>130, 132</Superscript>Ba and <Superscript>150</Superscript>Nd isotopes

The two-neutrino double-beta decay of ^{124, 126}Xe , ^{128, 130}Te , ^{130, 132}Ba and ¹⁵⁰Nd isotopes is studied in the Projected Hartree-Fock-Bogoliubov (PHFB) model. Theoretical 2ν β^-β^- half-lives of ^{128, 130}Te , and ¹⁵⁰Nd isotopes, and 2ν β⁺β⁺ , 2ν β⁺ EC and 2ν ECEC for ^{124, 126}Xe and ^{130, 132}Ba nuclei are presented. Calculated quadrupolar transition probabilities B(E2 : 0⁺ → 2⁺) , static quadrupole moments and g -factors in the parent and daughter nuclei reproduce the experimental information, validating the reliability of the model wave functions. The anticorrelation between nuclear deformation and the nuclear transition matrix element M _2ν is confirmed.     

Reorientation effect measurements in 124Te, 126Te and 128Te

Coulomb excitation probabilities of the first 2⁺ states of ¹²⁴Te, ¹²⁶Te and ¹²⁸Te have been determined. The measurement was performed by resolving the inelastically and elastically backward scattered ⁴He and ¹⁶O projectiles using an annular surface barrier detector. Quadrupole moments (Q₂₊) as well as the B(E2, 0⁺ → 2⁺) values were extracted by analyzing the excitation probabilities with the Winther-de Boer multiple Coulomb excitation program. The Q₂ deduced for the positive sign of the 2⁺ interference term are ?0.41 ± 0.08 e · b, ?0.144 ± 0.11 e · b and ?0.12 ± 0.09 e · b for ¹²⁴Te, ¹²⁶Te and ¹²⁸Te, respectively.     

Yrast excitations in A = 126–131 Te nuclei from deep inelastic 130Te+64Ni reactions

Thick target γγ coincidence measurements for the system ¹³⁰Te + 275 MeV ⁶⁴Ni have been performed using the GASP Ge detector array at Legnaro. For the isotopic assignments of previously unknown γ-ray cascades, prompt γγ coincidences observed between Te and Ni partner products were of vital importance. The results yield much new information about excited states of moderate spins in A = 126–131 tellurium nuclei, especially about yrast excitations of the little studied odd-A isotopes ¹²⁷Te, ¹²⁹Te, and ¹³¹Te. Level systematics of tellurium nuclei are presented, and both single-particle and collective aspects of the level spectra are discussed.     

Infra red photodetachment threshold measurements: Li− and P−

Using gaseous sources of I₂ and HI containing the radioactive isotopes¹²⁴I and¹²⁶I effective cross sections for nuclear resonance scattering from the first 2⁺ states of¹²⁴Te and¹²⁶Te were measured. Information is obtained about the charging of the nonradioactive molecular partner afterEC decay, the interaction of highly charged ions with neutral molecules, and the slowing down of atoms in a Xe buffer gas. Indications of an iodine complex being stable in the gaseous phase are found.     

Nuclear resonance fluorescence in124Te and126Te: Vacancy cascades in molecules

Using gaseous sources of I₂ and HI containing the radioactive isotopes¹²⁴I and¹²⁶I effective cross sections for nuclear resonance scattering from the first 2⁺ states of¹²⁴Te and¹²⁶Te were measured. Information is obtained about the charging of the nonradioactive molecular partner afterEC decay, the interaction of highly charged ions with neutral molecules, and the slowing down of atoms in a Xe buffer gas. Indications of an iodine complex being stable in the gaseous phase are found.     

A study of the giant dipole resonance in doubly even tellurium and cerium isotopes

The partial photoneutron cross sections [σ(γ, n) + σ(γ, pn)] and σ (γ, 2n) of ^{124, 126, 128, 130}Te and ^{140, 142}Ce were measured in the giant dipole resonance region by means of the monochromatic photon beam installation at SACLAY. Absolute total photoneutron cross sections, Lorentz line parameters and integrated cross sections are evaluated. The experimental behaviour of the GDR for the above nuclei and in particular its spreading, is then tentatively interpreted in terms of the improved dynamic collective model using the concept of potential energy surfaces.     

Determination of the static quadrupole moment of the first 2+ states of 122Te, 124Te,and 130Te by heavy-ion coulomb excitation

A Coulomb excitation experiment has been performed on the first 2⁺ states of ¹²²Te, ¹²⁴Te and ¹³⁰Te. The relative excitation probabilities of the first 2⁺ states were measured at backward and forward projectile scattering angles. Particle-γ coincidences were used to identify the inelastic events. The data were analyzed with the aid of the Winther-deBoer multiple Coulomb excitation program. Separate γ-ray angular distribution measurements were made as a function of target recoil velocity to determine the influence of the deorientation effect. The projectile and bombarding energy were chosen to minimize the effect on the experiment of higher state interference due to Coulomb excitation of the first 2⁺ state via the second 2⁺ state. For positive higher state interference the extracted quadrupole moments of the first 2⁺ states are Q₂₊ = ?0.43 ± 0.08 b, ?0.49 ± 0.08 b and ?0.08 ± 0.08 b for ¹²²Te, ¹²⁴Te and ¹³⁰Te respectively. These results and other measurements of Q_2⁺ for the doubly even Te isotopes are used to discuss the model dependent calculations of Q_2⁺.     

Structural investigation of Te-based chalcogenide glasses using Raman spectroscopy

Structural changes of metals (Zn, Sb, In, Ga) and metal halides (AgI, ZnI₂, CdI₂, PbI₂, BiI₃) modified GeTe₄ glasses were investigated with the aid of Raman spectroscopy. The Raman spectra of these glasses in the frequency region between 100 cm^?1 and 300 cm^?1 display four main bands at about 124, 140, 159 and 275 cm^?1 which are contributed by Ge–Te, Te–Te, Te–Te and Ge–Ge vibration modes. The intensity of 159 cm^?1 and 275 cm^?1 bands vary with the addition of different glass modifiers. While the relative intensity of the 124 cm^?1 and 140 cm^?1 bands are insensitive to composition changes. Glass modifiers like Zn, In and Sb act as glass network unstabilizer which will disorganize the glass network by opening up the chain structures of Ge–Te and Te–Te. In the case of Ga and metal halides, Ga can open up Ge–(Te–Te)_4/2 tetrahedra and form Ga–(Te–Te)_3/2 triangle. Iodine can form covalent bonds with tellurium and decrease the tendency of microcrystal formation. Thus both Ga and iodine ultimately act as glass network stabilizer.     

“Antialigned” members of the h11/2 family in123,125Te

Radiative neutron capture was studied on^122,124Te nuclei and the sequence of low spin levels based onh _11/2 orbital was identified in^123,125Te nuclei. The family of antialigned states was found to be compressed in energy, with respect to aligned states. This finding is in accord with similar observation made previously on other nuclei in this mass region and it can not satisfactorily be explained by existing nuclear models.     

On the paper “Nonexponential 125m Te radioactive decay” by S.K. Godovikov

An error is found in the experimental procedure used by S.K. Gogovikov, who recently reported on the detection of the γ decay of the ₂ ^125m Te nuclear isomer delayed by 22% due to the environment of these nuclei by numerous stable ¹²⁵Te nuclei.     

Cross-sections of isomeric state excitation of the 119Te and 121Te nuclei in (γ, n) reactions in an energy range of 9–20 MeV

The dependence of isomeric yield ratios upon the maximum bremsstrahlung gamma-quanta energy for the ¹²⁰Te(??, n)^119m,g Te and ¹²²Te(??, n)^121m,g Te reactions within an energy range of the giant dipole resonance is investigated. Cross-sections of excitation of metastable states with J ^?? = 11/2^? of the ¹¹⁹Te and ¹²¹Te nuclei are obtained. Experimental data are compared with computation results obtained using the TALYS-1.2 software package.     

Strong L=5 transition in Te(p,p′) reactions

Strong L=5 transitions have been found in the (p, p′) reaction on ^{122,124,126,128,130}Te. The possible 2⁵-pole collective motion in Te nuclei is discussed.     

Measurement of nuclear deformation parameters from elastic and inelastic scattering of α and 3He ions on Te isotopes

Cross sections for the elastic scattering of ⁴He by ^{122, 124, 126, 128}Te and ³He by ¹²⁸Te and for inelastic transitions to the lowest 2⁺ states of Te isotopes were measured for several scattering angles at bombarding energies in the vicinity of the Coulomb barrier. The data were analyzed in the framework of the optical model and the DWBA from which optical potential and deformation parameters were extracted. A detailed study of the fit procedure is presented with emphasis on the significance of the extracted parameters and the correlations among them.     

Evidence for particle-core coupling in the Te nucleus

The high-spin states of ¹²⁵Te have been investigated using the ¹²⁴Sn (α, 3nγ) reaction and the in-beam technique. Besides low-spin levels observed in the radioactive decay, the high-spin positive- and negative-parity bands have been established. As a possible explanation of the nature of the excited states in ¹²⁵Te the idea of the odd-neutron(hole)-core coupling is discussed.     

Dipole excitations in 122Te, 126Te and 130Te

Excited states of the nuclei ¹²²Te, ¹²⁶Te and ¹³⁰Te were populated via the (γ, γ') reaction at endpoint energies of the bremsstrahlung between 4.5 and 5.5 MeV. Gamma rays were detected with a EUROBALL-CLUSTER detector and a single detector. In all nuclei several dipole transitions were identified at energies around 3 MeV. The lowest corresponding J = 1 states are interpreted as two-phonon excitations. Quasiparticle-phonon-model calculations predict one 1^? state arising from the coupling of the first quadrupole and the first octupole phonon and one 1⁺ state arising from the coupling of the first and the isovector second quadrupole phonon at about 3 MeV. The calculated transition strengths are compatible with experimental ones.     

On the phenomenon of oscillatory decay of the <Superscript>125m</Superscript>Te isomer

The radioactive decay curve of the ^125mTe nucleus is measured in the environment of stable ¹²⁵Te nuclei representing a Mössbauer resonant screen. Thorough analysis shows that the decay of the ^125mTe nucleus corresponds to the standard exponential law with half-life T_1/2≈58 days without oscillations.