Dose assessment of bremsstrahlung induced by beta-emitting radioisotopes of uranium-238 series and lead in human tissues

In the natural uranium-238 decay series, pure beta isotopes such as ²³⁴Th, ²³⁴Pa, ²¹⁴Pb, ²¹⁴Bi, ²¹⁰Pb and ²¹⁰Bi are released. The few lead isotopes such as ²¹¹Pb, ²¹²Pb, ²¹³Pb and ²¹⁵Pb are good beta emitters. In certain nuclear reactions of reactor these isotopes are released. These beta isotopes have maximum beta energies, which induce the bremsstrahlung radiation. The bremsstrahlung component of these beta isotopes has been traditionally ignored in dosimetry calculations. The shapes of bremsstrahlung spectra are a basic ingredient in the understanding and quantification of beta-ray dosimetry. The bremsstrahlung spectra produced by these high-energy isotopes such as ²³⁴Th, ²³⁴Pa, ²¹⁴Pb, ²¹⁴Bi, ²¹⁰Pb, ²¹⁰Bi, ²¹¹Pb, ²¹²Pb, ²¹³Pb and ²¹⁵Pb in bone, muscle and teeth are studied, and the computed spectral distributions are presented. The spectral shapes are primarily responsible for variations in the shapes of depth–dose distributions. They are intended to provide a quick and convenient reference for spectral shapes and to give an indication of the wide variation in these shapes. The evaluated beta bremsstrahlung dose as a function distance for the studied nuclides is also presented. The efficiency, intensity and dose rate of bremsstrahlung induced by beta isotopes of natural uranium-238 decay series and beta-emitting lead isotopes in human tissues such as brain, breast, heart, kidney, liver, muscle, pancreas and bone have also been studied in the present investigation. The values of bremsstrahlung dosimetric parameters are low for pancreas, but they are high for bone. For all studied tissues these parameters are high for ²³⁴Pa, but low for ²¹⁰Pb.     

An analysis of some proton-nucleus scattering data at 1 GeV

The elastic and inelastic scattering data of 1 GeV protons on ¹²C, ³⁹K,^{40, 48}Ca, ⁵⁸Ni and ²⁰⁸Pb are analysed within the framework of Glauber theory. The collective excitations to one-phonon levels are treated using the Tassie model under the adiabatic approximation. Effects of both the coupling between the elastic and the inelastic channels and the two-body correlation in the intrinsic state are considered. The ground state and transition densities for the protons are taken from electron scattering experiments and appropriate assumptions for the neutron densities are made. In most of the cases, better agreement with the experimental data than reported in earlier analyses is obtained. The effects of the coupling and the pair correlation seem to be important only for ¹²C. The elastic data strongly indicate that the density distributions for protons and neutrons in ⁴⁸Ca and ²⁰⁸Pb are different. In ⁴⁸Ca, the surface envelope of the neutron distribution is found to be the same as for the proton distribution but is placed at a larger radius. On the other hand, the neutron distribution in ²⁰⁸Pb seems to be relatively much more diffuse.     

Spin-parity assignments of excited states in 12C

The reaction ¹²C(α, α')¹²C¹(3α) is observed by using 90 MeV a-particles in ionographic matter. The energies of the three α-particles from the break-up of ¹²C¹ are plotted in Dalitz diagrams. The density distributions for the three α-particles in the diagrams are calculated by assuming the spins and parities for the states in ¹²C¹(3α). The spin-parities for the states are assigned by comparing the observed density distributions with those calculated.     

Determination of Separated Plutonium,Americium and Curium in Environmental Samples by Sequential Extraction Techniques

A simple, reliable and practical radiochemical method for sequential isolation and determination of plutonium, americium and curium in a wide variety of environmental samples including soils, river sediments and water was developed. The isotopes determined are: ²³⁸Pu, ^239,240Pu, ²⁴¹Am, ²⁴²Cm and ²⁴⁴Cm. The methods involve leaching of soil or sedimental samples with concentrated nitric acid using a pressure digestion technique. Subsequent concentration and separation of nuclides of interest from major matrix elements and other interfering alpha-emitters are carried out by coprecipitation with ferric hydroxide and solvent extractions. Sources suitable for alpha-spectrometry are prepared by electrodeposition from acidic ammonium chloride solution. ²⁴²Pu and ²⁴³Am are used as tracer isotopes of plutonium and americium-curium elements, respectively. Some results of analysis of soils, sediments and water are given. The alpha peaks from ²³⁸Pu, ^239,240Pu and ²⁴²Pu as well as ²⁴¹Am, ²⁴⁴Cm, ²⁴²Cm and ²⁴³Am are well resolved. The entire analytical procedures for plutonium, americium and curium are completed in less than sixteen hours.     

Three-body muon-transfer collisions from hydrogen isotope to He<Superscript>2+</Superscript> and Li<Superscript>3+</Superscript> ions

The muon transfer rates from hydrogen isotopes (p,d) to ^3,4He²⁺ and ^6,7Li³⁺ ions are calculated in the hyperspherical close coupling method. Well converged results are obtained. The present rates are comparable to those of existing calculations for He²⁺, but they are much larger for Li³⁺. The resonance parameters are also calculated for resonances near the (Hμ)_1s threshold.     

Peripheral interactions of relativistic 14N nuclei with emulsion nuclei

The results of investigation of the dissociation of the 2.86-A-GeV/c ¹⁴N nucleus in an emulsion are presented. The cross sections for various fragmentation channels are given. The invariant approach to analysis of fragmentation is used. The momentum and correlation characteristics of the α particles for the ¹⁴N → 3α + X channel in the laboratory system and c.m.s. of three α particles are examined. The results obtained for the ¹⁴N nucleus are compared with similar data for the ¹²C and ¹⁶O nuclei.     

Radiative pion capture in 12C and 16O

Radiative pion capture in ¹²C and ¹⁶O is investigated. An effective interaction Hamiltonian based upon the CGLN theory is employed. Capture rates in ¹²C and ¹⁶O from Is and 2p pionic orbits are calculated by using the nuclear model of Kamimura, Ikeda and Arima for the odd parity states of ¹²C, and that of Walker with strong ground state correlations, for the odd parity states of ¹⁶O. The results are compared with those of the 1p-1h nuclear model under the Tamm-Dancoff and random phase approximations of Gillet and Vinh Mau. Detailed examinations are made for the transitions to low-lying states with 1⁺ and 2⁺ for ¹²C and with 1^?, 2^? and 3^? for ¹⁶O by using the Cohen-Kurath and the Walker models, respectively. The results are in good agreement with the recent experimental data from Berkeley.     

Isovector correlations and pion single charge exchange reactions in light nuclei

The reactions ⁷Li(π⁺, π⁰)⁷Be(g.s.), ⁷Li(π⁺, π⁰)⁷Be1(429keV) and ¹³C(π⁺, π⁰)¹³N(g.s.) are treated in DWIA, including corrections arising from two-step processes in which an intermediate state is reached in the course of the charge exchange. The distortions are introduced by means of a first-order optical potential; no special assumptions of extreme high energy limits are made. The closure sum over intermediate states in the two-step charge exchange mechanism leads to an isovector two-particle correlation function whose properties for p-shell nuclei are discussed in detail. Consequences of the introduction of effective transition operators for the single-step mechanism, with and without spin-flip, and for the two-step contribution are discussed, as are the allowable modifications in nuclear shell radii consistent with present knowledge of Coulomb energies. Comparison is made with experiment — in the case of the separated ⁷Be states, for the first time — and with other theoretical approaches.     

Excited states of HCl

Ab initio CI calculations are presented for potential curves for the valence states of HCl, for the vertical electronic spectrum and for the potential curve for the B ¹Σ⁺ state. The valence ¹Π, ³Π and ³Σ⁺ states are found to be repulsive. Calculated vertical excitation energies are in good agreement with experiment. The B ¹Σ⁺ curve is predicted to have a double minimum.     

Cold reaction valleys in the radioactive decay of superheavy 286112, 292114, and 296116 nuclei

Cold reaction valleys in the radioactive decay of superheavy nuclei ²⁸⁶112, ²⁹²114, and ²⁹⁶116 are studied taking Coulomb and Proximity Potential as the interacting barrier. It is found that in addition to alpha particle, ⁸Be, ¹⁴C, ²⁸Mg, ³⁴Si, ⁵⁰Ca, etc. are optimal cases of cluster radioactivity since they lie in the cold valleys. Two other regions of deep minima centered on ²⁰⁸Pb and ¹³²Sn are also found. Within our Coulomb and Proximity Potential Model half-life times and other characteristics such as barrier penetrability, decay constant for clusters ranging from alpha particle to ⁶⁸Ni are calculated. The computed alpha half-lives match with the values calculated using Viola-Seaborg-Sobiczewski systematics. The clusters ⁸Be and ¹⁴C are found to be most probable for emission with T _1/2 < 10³⁰ s. The alpha-decay chains of the three superheavy nuclei are also studied. The computed alpha-decay half-lives are compared with the values predicted by Generalized Liquid Drop Model and they are found to match reasonably well.     

Structural properties of the 10Be and 10C four-cluster nuclei

The structure functions for the ¹⁰Be and ¹⁰C nuclei are studied in a four-particle approximation (two alpha-particle clusters plus two nucleons). New versions of the αα interaction potential are constructed. Together with the nα, pα, and NN potentials proposed previously, they make it possible to describe the binding energies and radii of the nuclei being considered, along with the S-wave twocluster phase shifts at low energies. General properties of four-particle wave functions are studied, and two basic configurations of the cross and tetrahedron types are revealed in the ¹⁰Be and ¹⁰C nuclei. A detailed analysis of the behavior of the structure functions is performed for these nuclei. The density distributions, form factors, and pair correlation functions are considered. The momentum distributions are obtained for the alpha particles and extra nucleons. The structure functions for the ¹⁰Be and ¹⁰C four-cluster nuclei are compared with those for the ⁶He three-cluster nucleus. The bound states of the nuclei are studied within a high-precision variational approach by using Gaussian bases.     

Elastic and inelastic scattering of 79.5 MeV 11B and 87.5 MeV 10B ions

The elastic scattering of 79.5 MeV ¹¹B ions has been studied for seven targets ranging in mass from ²⁴Mg to ¹⁹⁷Au and of 87.5 MeV ¹⁰B ions for three of these targets (^{24, 25}Mg, ⁶⁰Ni). Angular distributions were measured from ~10° c.m. in steps of 0.5°, to angles beyond 40° c.m. where the elastic cross sections are ? 10^?3 of the Rutherford values (except for ¹⁹⁷Au). Inelastic data for exciting the lowest 2⁺ states of ^24,26Mg and ⁶⁰Ni were also obtained. Important odd-A-even-A differences are observed in the ¹¹B elastic angular distributions for the Mg and Al targets; for ¹⁰B scattering these are obscured by projectile quadrupole moment effects on the elastic scattering. The elastic data were analyzed using the optical model with potentials of both Woods-Saxon and double-folding form. The data for both ¹⁰B and ¹¹B are consistent with the potential obtained in the folding model with the M3Y interaction without renormalization. The inelastic data were analyzed by the distorted-waves method.     

The effect of gamma de-excitation competition on the (α, n) and (α, 2n) reactions on gold and antimony

Absolute cross sections for P¹⁹⁷Au(α, n)²⁰⁰Tl ¹⁹⁷Au(α, 2n)¹⁹⁹Tl, ¹²¹Sb(α, n)¹²⁴I and ¹²¹Sb(α, 2n)¹²³I are measured in the energy range from threshold to 27 Me V.The experimental results are interpreted in terms of evaporation statistical theory, including gamma de-excitation. The values of the level density parameters and of the average γ-ray strength for the compound systems are extracted.     

Theoretical study of the AlO blue-green (B2∑+−X2∑+ band system

Two independent, extensive theoretical calculations are reported for the relative band strengths of the AlO (B²∑⁺?X²∑⁺) blue-green system and for the radiative lifetimes of the lowest few vibrational levels of the B²∑⁺ state. The theoretical lifetimes, which include a small (<0.5%) contribution from bound-bound transitions into the A²Π state, are in excellent agreement with laser fluorescence studies. The theoretical lifetimes increase monotonically and very slowly with increasing vibrational quantum number. The relative band strengths for the blue-green system derived from the two theoretical calculations are in excellent agreement, but differ systematically from the relative band strengths of Linton and Nicholls. Our results suggest that their self-absorption corrections are not large enough, resulting in relative intensities that are too large, especially for the weak bands with r centroids less than 1.5Å.     

Coulomb forces in the three-body problem with application to direct nuclear reactions

Faddeev equations are considered in the case of three charged particles interacting with both separable nuclear two-body interactions and also including Coulomb forces. Modified Faddeev equations with Coulomb Green's functions are introduced. The three-body amplitudes are given into pure Coulomb and distorted-Coulomb amplitudes. Introducing a decomposition in the angular momentum states, a set of three-body integral equations is obtained. The effect of pure coulomb amplitudes is studied in direct nuclear reactions and found to give a large contribution to the cross sections. The three-body integral equations obtained are applied for direct nuclear reactions. The angular distributions for¹²C(⁶Li,d)¹⁶O,¹⁶O(⁶Li,d)²⁰Ne, and¹²C(⁶Li,α)¹⁴N transfer reactions are calculated as well as for the⁶Li elastic scattering on¹²C. From the good agreement between the theoretically calculated and experimental data, better spectroscopic factors are extracted. The effect of including Coulomb forces in the three-body problem is found to improve the results by about 16.26%.     

Shell model calculations of two to four identical-“particle” systems near 208Pb

The structure of the nuclei ^204–206Pb, ^210–212Pb, ²¹⁰Po, ²¹¹At, and ²¹²Rn is studied in terms of conventional nuclear shell models. An inert ²⁰⁸Pb core is assumed, and active particles (holes) are distuibuted in the low-lying single-particle (hole) orbits. Experimental single-particle energies are used for the one-body part of the effective residual interaction. Realistic interaction matrix elements developed for this mass region by Kuo and Herling are used for the matrix elements of the two-body part of the residual interactions. As much as possible, other effective one-body operators for electromagnetic observables are derived from experimental data on the single-particle (hole) nuclei ²⁰⁷Pb, ²⁰⁹Pb, and ²⁰⁹Bi. Observables treated are ground state binding energies, excitation energies, strengths for one- and two-particle transfers, and E2 and M1 observables. Generally, excellent agreement is found. The configuration mixing calculations do not remove anomalies in the magnetic moments of excited states in ²⁰⁶Pb and ²¹²Rn. Many states in these nuclei are predicted by the models which have not been observed as yet. It is found that a truncation scheme for doubly even nuclei treated here in which only seniority-0 and seniority-2 states are allowed is potentially very useful.     

Polarizabilities of ions in AgCl and AgBr

Two opposing mechanisms in silver chloride and bromide lead to polarizabilities which are for Ag⁺ about 30% smaller and for the anions about 10% larger than traditional values. The mechanisms are associated with the small lattice constants and exciton energies in AgCl and AgBr. Our best values in ų are Ag⁺ 1.67, Cl^? 3.29, and Br^? 4.55.     

Anisotropy of hyperfine field in diamagnetically substituted YIG

The results of the nuclear magnetic resonance of ⁵⁷Fe in Al-, Ga- and In-substituted Y₃Fe₅O₁₂ garnets are reported. When diamagnetic Ga³⁺ or Al³⁺ ions are substituted for tetrahedral Fe³⁺ ions, four satellite lines in the NMR spectrum of octahedral Fe³⁺ ions appear. The substitution of In³⁺ ions for octahedral Fe³⁺ ions leads to three satellite lines in the spectrum of tetrahedral Fe³⁺ ions. The hyperfine fields of these satellites are explained using the independent bond model for the hyperfine interaction. Suprisingly large change of the anisotropic part of the hyperfine field relative to the isotropic one was found.     

Spectroscopic studies of atmospheric interest on NO and NO

In recent years, high-resolution photoelectron spectroscopy and ab initio calculations have considerably revised and enlarged the understanding of the electronic structure of the NO and NO⁺ molecules. The experimental potential energy curves for the different electronic states of atmospheric interest molecules like NO and NO⁺ are constructed by using the Rydberg-Klein-Rees method as modified by Vanderslice et al. The ground state dissociation energies are determined by curve fitting technique using the five parameter Hulburt-Hirschfelder (H-H) function. The estimated dissociation energies are 6.381 and 10.693 eV for NO and NO⁺, respectively. These values are in good agreement with the literature values. The r-centroids and Franck-Condon factors (FC Factors) for the band system of B²Π_r-X²Π of NO and a³Σ⁺-X¹Σ⁺, A¹Π-X¹Σ⁺ of NO⁺ molecules have been calculated employing an approximate analytical methods of Jarmain and Fraser, and Nicholls and Jarmain. The absence of the bands in these systems is explained.