Cadmium Isotopes Research Articles

Nucleon density in the nuclear periphery determined with antiprotonic x rays: Cadmium and tin isotopes

The x-ray cascade from antiprotonic atoms was studied for 106Cd, 116Cd, 112Sn, 116Sn, 120Sn, and 124Sn. Widths and shifts of the levels due to strong interaction were deduced. Isotopic effects in the Cd and Sn isotopes are clearly seen. The results are used to investigate the nucleon density in the nuclear periphery. The deduced neutron distributions are compared with the results of the previously introduced radiochemical method and with HFB calculations.

Structure and Electronic Properties of the Heavy Transition Metal Pyrochlores and Weberites A<sub>2</sub>B<sub>2</sub>O<sub>7</sub>, A=Ca, Cd, Hg, Tl, Pb; B = Os, Ru, Re

Pyrochlores, A(2)B(2)O(7), containing late transition metals have gained considerable recent interest with the discovery of superconducting behaviour in Cd2Re2O7 and the characterisation of a pure Slater-like metal-semiconductor transition in Cd2Os2O7. In this presentation we will report the synthesis and full structural characterisation of a number of new and known phases of this type and in particular the solid solution Ca2-xCdxOs2O7. The synthesis of a range of 2(nd) and 3(rd) row transition metal pyrochlores has been achieved by direct reaction of component metal oxides in sealed tubes. Products, which include Ca2Os2O7, Hg2Os2O7, Cd2-xCdxOs2O7, Cd2Re2O7, Cd2Ru2O7, Hg2Os2O7, Tl2Os2O7-y, and Pb2Os2O7-x have been characterised by, powder neutron and X-ray diffraction over the temperature range 2K-900K; non-absorbing cadmium isotopes have been used where appropriate. Ca2Os2O7 adopts the weberite structure while the other A(2)B(2)O(7) type compounds crystallise with the pyrochlore structure. Calcium may be doped into Cd2Os2O7, as in Ca2-xCdxOs2O7, up to x =0.5 with retention of the pyrochlore structure. The electronic properties of these materials as a: function of structure and temperature are reported; all materials show metallic or poor metallic behaviour near room temperature.

Fusion-driven transmutation of elemental palladium-fission product

The paper deals with transmutation of elemental palladium separated from the spent fuel of fission reactors into the stable isotopes of silver and cadmium. The most efficient transmutation environment is achieved with resonance neutron spectrum in a blanket of fusion-driven transmuter. Three types of plasma conditioning are considered: DT-plasma with equal fractions of deuterium and tritium, DT-plasma with reduced tritium fraction and pure DD-plasma.

First observation of the intruder band in108Cd

The study of intruder and multiphonon configurations is of great interest in nuclear structure physics because it is related to single-particle and collective motion. The rarest of the stable cadmium isotopes was investigated with the powerful combination of two complementary experimental techniques: $\ensuremath{\gamma}\ensuremath{\gamma}$ spectroscopy following the $\ensuremath{\beta}$ decay of ${}^{108}\mathrm{In},$ and population of excited states using the nonselective $(\ensuremath{\alpha},n)$ fusion-evaporation reaction. The intruder band in ${}^{108}\mathrm{Cd}$ up to its ${4}^{+}$ member is established on the measurement of branching ratios of in-band and intraband decays supported by upper limits for the lifetimes using Doppler shift attenuation method. The heavily suppressed absolute $E2$ transition strength out of the proposed intruder band indicates this band structure to be fairly pure. These findings are compared to neighboring Cd isotopes and related six quasiproton structures. An analysis of the multiphonon structures observed in ${}^{108}\mathrm{Cd}$ and heavier Cd isotopes shows that the even mass cadmium chain forms a transitional path between the vibrational U(5) and the gamma-unstable O(6) limit with ${}^{108}\mathrm{Cd}$ closer to the O(6) description.

Determination of atomic isotope patterns from mass spectra of molecular ions containing multiple polyisotopic elements

A chemometrical method that allows one to obtain the isotopic abundances of the atoms composing a molecular ion, given its elemental composition and its mass spectrum, was developed. The method uses non-linear regression to fit the isotopic abundances of the elements, so that the experimental spectrum of the ion is reproduced. A least squares method with minimization by downhill simplex algorithm was implemented in C language as a library, but a graphical user interface application that allows an end-user to apply the method to his/her own spectra is also available. Examples of its application to electrospray mass spectra of NaAuCl 4 and CdCl 2 are given. The chlorine isotope pattern was obtained from the AuCl 4 − cluster in the former case and, simultaneously, chlorine and cadmium isotope patterns from the CdCl 3 − cluster. The performance of the method was extensively characterized by applying it to a great number of simulated spectra. Non-idealities, against which the method was evaluated, include noise, mass discrimination, detection non-linearity, base line offset (background counting), and low resolution. It has been demonstrated that, in spite of what intuition might tell one, the polyatomic approach to isotopic analyses has no a priori disadvantage to the common monatomic approach. Indeed, the results demonstrate that, in some cases, the figures of merit can be improved by using polyatomic species and that other polyisotopic elements can be included in the formula without significant loss of precision, as long as they have a dominant isotope, which is the case of carbon, hydrogen, oxygen, and nitrogen, for example. This means that polyatomic species derived from organic species could be useful for isotopic measurement purposes.

Partitioning and bioaccumulation of cadmium in artificial sediment systems: application of a stable isotope tracer technique

The utility of stable isotope tracers for investigating the relationship between cadmium (Cd) partitioning in artificial sediment–water systems and Cd accumulation in a benthic detritivore ( Asellus racovitzai, Isopoda) was explored. In the laboratory, Cd isotopes were applied to synthetic sediment and isotope concentrations were measured in sediment, overlying water and exposed asellids over a 10-day period. Isotope ratios measured in sediment and water were compared to ratios measured in asellids to determine whether Cd partitioning could predict metal bioaccumulation. Two different parameters which might affect Cd partitioning between the sediment and overlying water compartments were investigated: the chemical form in which Cd was added to systems, and the organic matter content of the sediment. To test the effect of chemical form on Cd partitioning, three isotopes of cadmium were individually applied to formulated sediment in varying combinations of 113 Cd( NO 3) 2 , 112Cd-humic acid (HA) 114 CdSO 4 . The results demonstrated that chemical form did not influence partitioning, as the Cd isotope that was applied to sediment in the nitrate form exhibited similar partitioning between sediment and overlying water as the isotope that was applied in the sulfate or HA form. However, Cd isotope concentrations in overlying water were strongly related to the pattern of isotope accumulation in asellids suggesting that overlying water concentrations determined Cd bioaccumulation. In contrast, when the organic matter content of sediment was increased through the addition of Sphagnum peat moss, total Cd concentrations in overlying water and tissue were low, and there was no relationship between Cd-isotope concentrations in tissue and water. These results indicate that Cd accumulation occurred primarily from water, and factors that increase metal partitioning to sediment, such as increased sediment organic matter content, decrease Cd accumulation in asellids. The stable isotope tracer method described herein appears to be a useful technique for investigating the relationship between metal partitioning and bioaccumulation in simple sediment systems, but could also be extended to more complex systems, and used with different metals that have multiple stable isotopes.

Evidence for deformation in 113-116Cd isotopes

High-spin states in 113-116Cd have been investigated with the fusion-fission reaction 28Si +176Yb at 145 > MeV. The experiment has been performed with the Eurogam2 array. New rotational bands based on two quasi-particle states have been observed for even-even cadmium isotopes. A new level scheme based on the 11/2− isomeric state is proposed for 115Cd and the one of 113Cd has been extended to spin (31/2−). The decoupled bands identified in both odd-A nuclei are interpreted as being built upon a low-Ωh11/2 quasi-neutron configuration. Microscopic Hartree-Fock + BCS calculations confirm the prolate deformation in this mass region especially for the odd cadmium isotopes.

Metallothionein Levels in Cell Fractions from Breast Cancer Tissues

Metallothioneins (MTs) protect the cell against reactive forms of oxygen, ionizing radiation, pharmacological agents and mutagens. Metallothioneins are also responsible for neoplastic cell resistance to cytostatic drugs. The aim of this study was to determine the MT level in cell fractions as well as to determine whether there is any change in the concentration of these proteins in a neoplastic cell, and in which cell fractions this change takes place. The neoplastic tissue examined was histopathologically ductal carcinoma invasive, and the control tissue was mastopathic tissue with proliferated connective and glandular tissue. The level of MTs was determined using cadmium isotope (109Cd). It was determined that there was an increase in MT level in the neoplastic tissue, the highest level being found in the mitochondrial fraction obtained from the control and mastopathic tissues. The greatest changes in MT concentrations in breast carcinoma were observed in the nuclear and cytosol fractions. In the nuclear fraction in the breast carcinoma tissue, the MT level was almost three times that of the control group.

High-spin structure of the 113–116Cd isotopes produced by heavy-ion induced fission reaction

High-spin states in 113–116Cd have been investigated with the heavy-ion induced fission reaction 28Si + 176Yb at 165 MeV. The experiment was performed with the Eurogam II array. New rotational bands based on two quasi-particle states have been observed for even-even cadmium isotopes. A new level scheme based on the 11/2– isomeric state is proposed for 115Cd and the one of 113Cd has been extended to spin (31/2–). Hartree–Fock calculations for even-even isotopes show a prolate deformation in this mass region. The decoupled bands identified in both odd nuclei are interpreted as being built upon a low-Ω11/2 quasi-neutron configuration.

Preliminary investigation of electrothermal vaporization sample introduction for inductively coupled plasma time-of-flight mass spectrometry.

The coupling of an electrothermal vaporization (ETV) apparatus to an inductively coupled plasma time-of-flight mass spectrometer (ICP-TOFMS) is described. The ability of the ICP-TOFMS to produce complete elemental mass spectra at high repetition rates is experimentally demonstrated. A signal-averaging data acquisition board is employed to rapidly record complete elemental spectra throughout the vaporization stage of the ETV temperature cycle; a solution containing 34 elements is analyzed. The reduction of both molecular and atomic isobaric interferences through the temperature program of the furnace is demonstrated. Isobaric overlaps among the isotopes of cadmium, tin, and indium are resolved by exploiting differences in the vaporization characteristics of the elements. Figures of merit for the system are defined with several different data acquisition schemes capable of operating at the high repetition rate of the TOF instrument. With the use of both ion counting and a boxcar averager, the dynamic range is shown to be linear over a range of at least 6 orders of magnitude. A pair of boxcar averagers are used to measure the isotope ratio for silver with a precision of 1.9% RSD, despite a cycle-to-cycle precision of 19% RSD. Detection limits of 10-80 fg are calculated for seven elements, based upon a 10-microL injection.

Computing experiments for study of cadmium isotope separation by gas centrifuges

The basic regularities for enrichment of the 116Cd isotope in the form of cadmium dimethyl in a single gas centrifuge and a square cascade of gas centrifuges have been studied by means of numerical simulation techniques. In these computing experiments it has been found the influence of a loss of the process gas due to its partial decomposition to enrichment of the desired isotope.

Centrifugal enrichment of cadmium isotopes as the basis for further experiments on physics of wak interactions

Some data on cadmium isotope separation by means of gas centrifuges are presented.

Decay properties of very neutron-deficient isotopes of silver and cadmium

The β-decay properties of the lightest known silver and cadmium isotopes are investigated. Data for β-delayed γ-ray emission of 95–97Ag and for β-delayed proton emission of 96Ag and 97Cd are presented. The experimental findings are compared with predictions of shell-model calculations in which a variety of model spaces and effective interactions are considered.

Diffusion-based separation methods: Dry distillation of zinc, cadmium and mercury isotopes from irradiated targets

Diffusion-based separation methods allow the extraction of produced radionuclides with a low loss of target material, which is of special importance when enriched target material is used. We present a simple, non-destructive and rapid method to separate radioactive isotopes of IIB group elements (zinc, cadmium and mercury) from IB group metal targets irradiated with protons. Irradiated target foils were heated to a temperature 20°C below the melting point of the target materials. During these conditions at least 90% of the desired radioactivity was evaporated with negligible loss of target material. Separation time was 15 min for mercury, 60 min for cadmium and 120 min for zinc.

Transmutation doping of wide-bandgap II–VI compounds

Transmutation doping of the wide-bandgap semiconductors CdTe and ZnTe by radioactive cadmium isotopes have been carried out. A doping efficiency close to 100% was obtained, if the thermal formation of native point defects is avoided. To identify the origin of doping we studied the time-dependent C- V-characteristics using the half-life as fingerprint.

A mass‐spectrographic study of the isotopes of argon, potassium, rubidium, zinc and cadmium

AbstractA mass spectrograph is described with which a study of the isotopic constitution of argon, potassium, rubidium, zinc and cadmium has been made. A calculation is carried out which indicates that the radioactivity of potassium and rubidium can best be explained by assuming that it is K40 in the case of potassium and Rb87 in the case of rubidium which is undergoing decay.

Systematic QRPA study of β− and decay transitions to excited states of 110–114Cd and 114–122Sn

Abstract A systematic study of the β− and β + EC decay transitions of odd-odd nuclei into the ground state, first excited quadrupole state (21+) and the two-quadrupole-phonon triplet (02ph+, 22ph+ and 42ph+) of the final even-even nuclei 110–114Cd and 114–122Sn is performed. In these cases the states of the even-even nucleus are fed both by β− as well as β + EC decay transitions of the two adjacent double-odd nuclei. Such exceptional circumstances help to study the β− and β + EC Gamow-Teller decay on equal footing starting from the predictions of the combined QRPA and pn-QRPA theories. In addition, the differences between the QRPA and the QTDA predictions are discussed. The present approach tests systematically the theoretical β− and β + EC matrix elements and might be used for identification of states belonging to the two-quadrupole-phonon multiplet in the spectra of the cadmium and tin isotopes.

Neutron resonance spectroscopy on 113Cd to En=15 keV.

The results of a study of the compound nucleus [sup 114]Cd by neutron time-of-flight spectroscopy methods are presented. Targets of both natural cadmium and cadmium enriched in the 113 isotope were used. The neutron total capture and neutron transmission were both measured. A total of 275 new resonances were located. In addition, 102 other resonances which were previously known but not assigned to a particular cadmium isotope were definitively assigned to [sup 113]Cd. Resonance parameters [ital E][sub 0] and [ital g][Gamma][sub [ital n]] were obtained for both newly identified and previously known resonances. Of the 437 resonances now known in [sup 113]Cd, we identify 104 of them as [ital l]=1 based on their small widths. Strength functions and level spacings are obtained for both [ital l]=0 and [ital l]=1 resonances. Comparisons of the data with Porter-Thomas reduced width distributions, Wigner nearest neighbor spacing distributions, and the Dyson-Metha [Delta][sub 3] statistic are given. The linear correlation coefficient between adjacent spacings is also discussed. The spectroscopic information obtained is of importance for planning and interpretation of parity violation measurements on the [ital p]-wave resonances of [sup 113]Cd.

Scattering of 22.3 MeV polarized protons from the even-mass cadmium isotopes 106-116Cd

Measurements have been done on polarized-proton scattering from the even-mass cadmium isotopes 106-116Cd, at a beam energy of 22.3 MeV. The experimental data were analysed using first- and second-order vibrational models in a coupled-channels formalism. The 01+, 21+ and 31- levels are represented satisfactorily by theory. In 106-116Cd the 22+ and 41+ levels were resolved; for the 22+ levels the theory systematically underestimates the first diffraction maximum of the cross section at 30 degrees while the 41+ levels are reproduced reasonably well. In 112-114Cd the 02+ level could also be studied; there are indications for a strong coupling between the two-phonon 0+ state in the ground-state band and the 0+ head of the intruder band. In 114Cd we also investigated the 23+ level, probably the first excited state of the intruder system, which showed an angular pattern with more pronounced details than the 21+ states. Finally in 112Cd the 11$and 51- levels were studied which have a strong direct coupling to the ground state.

Rotational bands and neutron alignments in neutron rich odd-A cadmium isotopes.

High-spin states in [sup 109,111]Cd have been investigated with the reaction [sup 96]Zr([sup 18]O,[ital xn])[sup 114[minus][ital x]]Cd at beam energies of 60 and 70 MeV. The decoupled yrast bands observed in both nuclei are interpreted as being built upon a low-[ital Kh]11/2-quasineutron configuration. Both structures exhibit band crossings corresponding to the rotational alignment of a pair of [ital h]11/2 quasineutrons. Two positive-parity bands built on a [ital g]7/2-quasineutron configuration are observed in [sup 109]Cd. These exhibit a signature inversion in the region of the first ([nu][ital h][sub 11/2)][sup 2] alignment. This may be associated with some softness to triaxiality. The results are discussed in terms of the cranked shell model, total Routhian surface calculations, and the systematics of neighboring nuclei.