Interference phenomena in heavy ion induced two-nucleon transfer reactions

A coupled channels calculation including multistep inelastic excitations induced by nuclear as well as Coulomb interactions has been performed for the reactions ¹⁴⁸Sm(¹⁸O, ¹⁶O) and ¹⁵⁰Sm(¹⁶O, ¹⁸O). The 2⁺ states were treated as vibrational, using BCS + RPA wavefunctions. The calculation is consistent with experimental data, both as far as absolute cross-sections are concerned, and also in explaining the different interference pattern of the 2⁺ states, near the grazing angle, in stripping and pick-up.     

Spin polarization of β-emitting fragments in high energy heavy ions on Be collisions

The degrees of nuclear spin polarization of ^8,12B, ⁹C, ¹²N, ¹³O, ^20,21F, ²³Mg, ²⁷Si and ³⁹Ca produced in the high energy ^12,13C, ¹⁶O, ²²Ne, ²⁴Mg, ²⁸Si and ⁴⁰Ca ions on Be collisions have been measured systematically, for the technical developments of the nuclear moment studies as well as the hyperfine interaction studies by means of β-NMR technique. The fragment momentum dependences were well reproduced by the simple kinematical model. Incident energy dependence and the mass dependence as well as the reaction angle dependences were qualitatively explained by the mixing of the near and far side collisions. This revised version was published online in August 2006 with corrections to the Cover Date.     

Competition between exit channels leading to the same residual nucleus in heavy-ion reactions

Competition between pn and d as well as between p2n, dn and t emission in the production of individual residual states has been observed in nuclear reactions induced by ¹⁶O on ¹²C and ¹³C targets. The experimental relative yields for the production of the 417 keV state in ²⁶Al by pn and d emission, measured as a function of bombarding energy in the reaction ¹²C(¹⁶O,pn/d)²⁶Al, are successfully described by Hauser-Feshbach calculations.     

Partial photoionization cross-sections and branching ratios of CO from 750 to 304 Å

The absolute values of the partial photoionization cross-sections and branching ratios for producing carbon monoxide ions in their X²Σ⁺, A²Π, B²Σ⁺ and ²Σ⁺(σ2s) states have been obtained as a function of wavelength from the A²Π ionization threshold to 304 Å. Results have been obtained within autoionizing resonances as well as within the photoionization continuum.     

Hyperfine interaction and g-factor measurements in Er isotopes

Energy levels in ¹⁶⁰Er and ¹⁵⁹Er were excited in the reactions ²⁸Si(¹³⁶Xe, 4n)¹⁶⁰Er and ²⁸Si(¹³⁶Xe, 5n)¹⁵⁹Er, and the product nuclei, recoiling with a velocity v = 0.07c were stopped in a plunger instrument after traversing a volume of hydrogen gas. The angular distribution of de-excitation γ-rays was studied as a function of flight time and gas pressure. Appreciable perturbations were detected in ¹⁶⁰Er at times as short as 2 ps and in an angular momentum region as high as 12?. No perturbation could be detected in the $\text{21}\text{2}{}^{\mathrm{+}}$ level of ¹⁵⁹Er even after 12 ps, signifying a low value for the g-factor of this level.     

Fluorescence Sensors for Selective Detection of Hg2+ Ion Using a Water-Soluble Poly(vinyl alcohol) Bearing Rhodamine B Moieties

The novel water-soluble poly(vinyl alcohol) with pendant rhodamine B moiety as colorimetric and fluorescene chemosensor for Hg²⁺ ions was prepared by grafting poly(vinyl alcohol) using rhodamine B hydrazide and hexamethylenediisocyanate as fluorescent dye and coupling agent, respectively. Because of their good water-solubility, the polymers binding rhodamine B can be used as chemosensors in aqueous media. With the addition of Hg²⁺ ions into the aqueous solution, visual color changes and fluorescence enhancements were detected. In addition, we also noticed that other metal ions such as Ag⁺, Cd²⁺, Co²⁺, Cu²⁺, K⁺, Mg²⁺, Ba²⁺, Fe²⁺, Ni²⁺, Pb²⁺, Cr³⁺, Fe³⁺ and Zn²⁺ cannot induce obvious changes to the fluorescence spectra of the polymer chemosensors. The combination of water solubility and positive fluorescence response as well as color change are hence particularly promising for the practical utility of the sensors.     

Deformation effects in the 28Si+12C and 28Si+28Si reactions

The possible occurrence of highly deformed configurations is investigated in the ⁴⁰Ca and ⁵⁶Ni di-nuclear systems as formed in the ²⁸Si + ¹²C, ²⁸Si reactions by using the properties of emitted light charged particles. Inclusive as well as exclusive data of the heavy fragments and their associated light charged particles have been collected by using the ICARE charged particle multidetector array. The data are analysed by Monte Carlo CASCADE statistical-model calculations using a consistent set of parameters with spin-dependent level densities. Significant deformation effects at high spin are observed as well as an unexpected large ⁸Be cluster emission of a binary nature.     

Computer simulation of high-energy proton-nucleus fragmentation cross-section

A computer simulation code is designed to imitate the mass yield fragmentation cross-section as a result of high energy P-N interaction, as well as other effective distributions influencing it. The Monte-Carlo fragmentation is discussed in the framework of an equilibrium macrocanonical statistical model. The code is used to investigate the mass yield cross-section of U²³⁸ as well as the Coulomb potential distributions of U²³⁸, Au¹⁹⁰, Ta¹⁸¹, Xe¹²⁷, Cu⁶⁴ nuclei. The comparison of predicted yield cross-section with experimental measurements exhibited tolerable agreement, furthermore, the binary fisson cross-section is formulated in terms of target and fragment mass numbers as well as the expectation values of Coulomb potential are formulated in terms of target and fragment atomic numbers,Z _t andZ _f, respectively.     

The knockout reaction of <Superscript>15</Superscript>C on a <Superscript>9</Superscript>Be target at intermediate energies

In this work, neutron knockout reactions of ¹⁵C on a ⁹Be target at energy 103 and 250 MeV/nucleon are studied. Using the Eikonal approximation of the Glauber model, total neutron removal cross sections, the stripping and diffractive cross sections as well as ¹⁴C longitudinal momentum distributions are determined in both ¹⁵C ground state and exited states of the wave function. We compared the results of our calculations with the available experimental data obtained recently. The calculated cross sections of ¹⁵C and ¹⁴C reactions, as well as the momentum distribution are in relatively good agreement with available data.     

210Pb in magnesium dietary supplements

The idea behind this study was to investigate the most popular magnesium dietary supplements as a potential additional source of ²¹⁰Pb in the human diet. The paper presents the results of ²¹⁰Pb activities determined in different magnesium supplements, as well as an estimation of the annual effective radiation doses from ²¹⁰Pb decay. The results showed that the highest value of ²¹⁰Pb activity was found in a magnesium supplement of natural origin (dolomite) with a value of 2.97?±?0.18 mBq g^–1. The highest annual radiation dose from ²¹⁰Pb obtained from the magnesium daily recommended value (0.4 g of pure Mg) was calculated for dolomite tablets as 3.71?±?0.02 µSv·year^–1.     

Investigation of cosmogenic radionuclide carriers in the atmosphere

Speciation of ⁷Be, ³²P, ³³P, ³⁵S and stable S carriers and their changes in the atmosphere were investigated. It has been determined that aerosol-carriers of ⁷Be, ³²P and ³³P radionuclides can have different properties, and after several days their transformation was observed. The amount of water-soluble carriers in aerosol samples differed widely (from 11 to 95%). The dependence of radionuclide carrier solubility on pH was obtained for ⁷Be, ³²P and ³³P. It has been found that ⁷Be carriers can be soluble compounds such as mixed chlorides, sulphates and nitrates as well as insoluble carbonates and insoluble hydrous Fe(III) oxides. High percentage of ³²P and ³³P was found in exchangeable fraction. The ³⁵S carriers were found to be more soluble than those of ⁷Be, ³²P and ³³P and exhibited a lower or the same solubility as stable sulphur.     

Enhancement of Tb emission by non-radiative energy transfer from Dy in silicate glass

A study of energy transfer was performed in dysprosium-terbium-doped silicate glasses at room temperature. Enhancement of the Tb³⁺ emission and a decrease in the Dy³⁺ emission are observed as a result of energy transfer from Dy³⁺ ions to Tb³⁺ ions. The energy transfer efficiencies, transfer probabilities, as well as average donor-acceptor distances were also calculated. It is concluded that the energy transfer mechanism between Dy³⁺ and Tb³⁺ ion is mainly electric dipole-dipole in nature.     

Non-orthogonality effects in heavy-ion transfer reactions

Calculations are made of the effects arising from the non-orthogonality of channel states in heavy-ion neutron transfer reactions, as well as the associated elastic-scattering processes. A single iteration is performed upon the integral equations associated with the coupled-channel treatment of the transfer process. The reactions considered are ¹³C(¹⁶O, ¹⁷O)¹²C leading to the ground state and first excited state of ¹⁷O and the ²⁹Si(¹⁶O, ¹⁷O)²⁸Si reaction leading to the first excited state of ¹⁷O. Corrections are found to be as large as 10 % at angles where the cross sections are sizeable. Similar results are obtained for the elastic-scattering processes. The choice of reactions was made so as to emphasise the importance of these corrections.Consideration of the errors associated with the depiction of bound states in terms of a sum of Hankel functions and the use of a local-momentum approximation for the channel motion suggests that the figure for the correction represents an upper bound.     

Production and decay of W boson in electron-positron annihilation

We study the characteristics of the μe events due to e⁺e^? → W⁺W^? and the subsequent leptonic decay of W^±, in the Weinberg-Salam model. The differential cross section for W production is given for non-polarized electron-positron beams as well as transversely polarized beams. The energy angle distributions as well as angular correlations of the final μe events are presented for beam energy of 100 + 100 GeV. Potential backgrounds are also discussed.     

Beta decays of 44V and 52Co

We have studied the prevously unknown β⁺ decay branches from ^44,44mV and ⁵²Co to particle-bound states in ⁴⁴Ti and ⁵²Fe, respectively. These intense branches populate a few states in the daughters from an excitation energy of about 1 MeV up to the isobaric analogue states at about 6 MeV. We have measured the first precise energy values for the latter states as well as the β-branching ratios to all states in this excitation energy region. We have calculated the β⁺ decay of ^44,44mV in the full fp shell model space as well as in a truncated space. Renormalized transition operators are constructed for the truncated space and tested against experimental data in ⁴⁴V and ⁵²Co. In general there is good agreement between theory and experiment for the half-lives, level energies and beta branches, but not all the states found are reproduced by the calculations.     

Tensor polarization of 12C(2+), 24Mg(2+), and 28Si(2+) oriented nuclei

Measured and calculated angular dependences of components of the polarization tensor of a ¹²C nucleus in the 2⁺ state at 4.44 MeV formed in various reactions involving light particles, as well as ²⁴Mg(2⁺, 1.369 MeV) and ²⁸Si(2⁺, 1.78 MeV) nuclei formed in inelastic alpha-particle scattering, are presented. The experimental tensor polarization in question was reconstructed on the basis of the densitymatrix spin-tensors found previously for these nuclei. The parameters of the quadrupole and hexadecapole orientation of the nuclei under study were obtained. The experimental polarization features were compared with the results of calculations based on the coupled-channel method. Special features of the behavior of tensor polarizations in various reactions were discussed. The similarity of the experimental angular dependences of the components of tensor polarizations in inelastic deuteron and ³He scattering on ¹²C nuclei, as well as in inelastic alpha-particle scattering on ²⁴Mg and ²⁸Si nuclei, was demonstrated.     

Absolute frequency measurements of the 0002-0000, 2001-0000, and 1201-0000 bands of N2O by heterodyne spectroscopy

The absolute frequencies of 39 lines in the 00⁰2-00⁰0, 20⁰1-00⁰0, and 12⁰1-00⁰0 bands of N₂O in the range 4300–4800 cm^?1 have been measured by heterodyne frequency techniques. The lines were each measured in Doppler-limited absorption, with a color-center laser as a tunable probe of the N₂O and two stabilized CO₂ lasers as reference frequencies. New rovibrational constants have been fitted to these measurements. Tables of calculated transition frequencies are given, with estimated absolute uncertainties as small as 10^?4 cm^?1. The pressure shifts of four lines have been measured, and the values fall within the range of 0 to ?2 MHz/kPa (0 to ?0.2 MHz/Torr).     

Electron transfer in low energetic Ne2+/Ar,Kr collisions

Single electron capture processes in Ne²⁺/Ar, Kr collisions were studied by aid of the high-resolution translational spectroscopy. At low collision energies (<1 keV) the dominant contribution to the Ne⁺-spectrum arises from Ne²⁺ ions in the metastable¹ S ₀-state, although it is the weakest component of the primary Ne²⁺ beam. Ne²⁺(³ P) and Ne^2+*(¹ D) projectiles play no important role due to unfavourable energy defects. Target excitation processes as well as transfer ionisation are considered as a possible explanation for different structures in the measured Ne⁺ spectra.     

Search for low-energy resonances in 21Ne(p, γ)22Na and 22Ne(p, γ)23Na

The reactions ²¹Ne(p, γ)²²Na and ²²Ne(p, γ)²³Na have been investigated at E_p(lab) = 70–355keV. Neon gas enriched to 91% in ²¹Ne and to 99% in ²²Ne was recirculated in a differentially pumped gas target system of the extended-static and quasi-point supersonic jet type. For ²¹Ne(p, γ)²²Na, new resonances were found at E_p = 126, 272, 291 and 352 keV. The 291 keV resonance corresponds to a new unbound state in ²²Na. Excitation energies, γ-ray decay schemes, resonance widths and strengths as well as J^π assignments are reported for all the resonances. Information on low-lying states in ²²Na is also obtained. Of the 9 expected resonances in ²²Ne(p, γ)²³Na none has been observed. Upper limits on their ωγy strengths are presented. The astrophysical as well as the nulcear structure aspects of the results are discussed.     

Annealing behaviour of iron implanted zirconia

A zirconia film was implanted at room temperature with 100 keV⁵⁷Fe⁺ to a fluence of 8×10¹⁶ ions/cm². The analysis of the Conversion Electron Mössbauer spectra shows that iron is distributed among different charge states: Fe⁰ (in a form of small and large metallic iron aggregates) Fe²⁺ and Fe⁴⁺. The evolution of the iron depth profile deduced from Rutherford backscattering measurements as well as the change in the charge states of iron as a function of annealing under argon atmosphere are presented.