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This article is devoted to obtaining the α-emitter Tb for radioimmunotherapy. A method for producing Tb based on the reaction Eu(He, 5n)Tb is proposed. It is proposed that europium with native isotopic composition (Eu - 47.81%, Eu - 52.19%) or enriched Eu be used as the target. The 29 MeV threshold of the indicated reaction makes it possible to use accelerators with the initial He energy 40-70 MeV. [ABSTRACT FROM AUTHOR]

The ability of black carbonaceous siltstones and silt sandstones, lime sandstones, gray limestones, carbon-silicon carbonate schists with pyrite, and other rocks that most widely occur on the Novaya Zemlya Archipelago to sorb Cs, Sr, Pu, and Am was studied. The distribution coefficients K (cm g) are as follows: for Pu, 2.7 × 10-7.7 × 10; for 241Am, 2.5 × 10-1.8 × 10; and for Cs, 1.1 × 10-2.0 × 10. Strontium-85(90) it not noticeably sorbed (within the measurement uncertainty) by any of the rocks studied. Pu, Am, and Cs are strongly sorbed onto the rocks studied and are not noticeably desorbed from them with distilled water. The data obtained are required for predicting the migration of long-lived radionuclides generated by nuclear explosion with surface waters from test sites on the Novaya Zemlya Archipelago. [ABSTRACT FROM AUTHOR]

Distribution of Po in thalli of soil and wood (epiphytic) lichens was studied. Four fractions containing the corresponding Ро forms were obtained by sequential extraction: (1) intercellular, (2) extracellular, (3) intracellular, and (4) insoluble thallus residue. The Ро uptake by lichens is mainly passive, as the total content of the radionuclide in fractions 1, 2, and 4 reaches 88-97%. From 3 to 12% of Ро is taken up actively (fraction 3), and for soil lichens this parameter is approximately 2.75 times higher than for epiphytic lichens. Presumably, Ро is supplied into soil and epiphytic lichens in the form of different chemical compounds and is therefore characterized by different bioavailability. [ABSTRACT FROM AUTHOR]

Fast radioanalytical methods are essential for a rapid response of decision makers. A fast method for the simultaneous determination of the pure beta emitting radionuclides Sr/Sr and Tc in food samples was developed. It includes the precipitation of fat and proteins with trichloroacetic acid for milk and dairy products and microwave digestion for other food products, followed by an anion exchange step to separate strontium from technetium. The purification steps for strontium and technetium are done using Sr-resin and TEVA-resin, respectively. Typical chemical yields are around 70 % for both radionuclides. The whole determination takes only around 20 h. [ABSTRACT FROM AUTHOR]

As part of the verification component of the Comprehensive Nuclear-Test-Ban Treaty (CTBT), environmental gas samples originating from nuclear fission are analyzed for the presence of Xe, Xe, Xe, and Xe. In this work, the non-traditional radioxenon isotope Xe was investigated. The isotope was produced as an isotopically pure sample via neutron activation of Xe at the University of Texas at Austin Nuclear Engineering Teaching Lab's TRIGA MARK II Reactor. The sample was then measured using a HPGe detector as well as an ARSA-style β-γ coincidence detector. Potential sources and sensitivities for production of Xe are also considered for relevance to the CTBT verification mission. [ABSTRACT FROM AUTHOR]

In this study, measurement of natural radioactivity and analyses of physical properties of soil were carried on great soil groups around the Seferihisar Geothermal Region. The radioactivity levels in soils were analyzed using scintillation gamma spectroscopy. The activity concentrations for Ra, Th, and K range from 7.1 to 32.0 Bq kg, 15.2 to 35.9 Bq kg and 223.1 to 802.2 Bq kg, respectively. Obtained data was compared with average values given by UNSCEAR and the other studies. The radium equivalent activity (Ra) in soil samples ranges from 42.2 to 144.7 Bq kg which are lower than the suggested maximal admissible value of 370 Bq kg recommended by OECD. In addition, the value of external exposure dose has been determined from the content of natural radionuclides in soil. The absorbed dose rates change between 20.6 and 70.9 nGy h with a mean value of 46.7 nGy h which is lower than the global average value of 55 nGy h. The annual effective dose rates varied from 25.2 to 87.0 μSv year with an average value of 57.3 μSv year. Obviously, all the calculated values were lower than this value, and therefore the environment of Tuzla Fault can be regarded as an area with normal natural background radiation. [ABSTRACT FROM AUTHOR]

The use of the tools of formal chemical kinetics for calculating the total α-, β-, and γ-ray spectra in decay of radioactive isotopes is suggested. Principles of constructing a reaction scheme modeling the radioactive decay of the initial isotope and chain of its daughter nuclides are described. The reaction scheme allows calculation of the total current radiation spectra, total decay energy, and gas (He) formation along with variation of the isotope composition. [ABSTRACT FROM AUTHOR]

Extensive hydrogeological investigations followed by three-dimensional groundwater flow and contaminant transport modelling were carried out around a proposed uranium tailings pond at Seripalli in Andhra Pradesh, India, to estimate its radiological impact. The hydrogeological parameters and measured groundwater level were used to model the groundwater flow and contaminant transport from the uranium tailings pond using a finite-element-based model. The simulated groundwater level compares reasonably with the observed groundwater level. Subsequently, the transport of long-lived radionuclides such as U, U, Th and Ra from the proposed tailings pond was modelled. The ingrowths of progenies were also considered in the modelling. It was observed that these radionuclides move very little from the tailings pond, even at the end of 10,000 y, due to their high distribution coefficients and low groundwater velocities. These concentrations were translated into committed effective dose rates at different distances in the vicinity of the uranium tailings pond. The results indicated that the highest effective dose rate to members of the public along the groundwater flow pathway is 2.5 times lower than the drinking water guideline of 0.1 mSv/y, even after a long time period of 10,000 y. [ABSTRACT FROM AUTHOR]

It has been demonstrated that pixel-by pixel processing of series of autoradiography images for revealing the dynamics of decay of the induced radionuclides is an efficient approach for mapping of radionuclides in the sample in activation autoradiography. Concepts of virtual scanner and corresponding software for linearization of dependence of optical density on scanner response (luminosity) have been introduced. The concept provides unification of the subsequent processing of autoradiograms, irrespective of the method as to how the digital image has been obtained. Algorithms and the software for estimation of decay parameters of a radionuclide mixture for each pixel using a series of coaxially positioned images have been developed. The software is able generate a set of the derivative meta-images allowing a conclusion to be made about the presence of the inclusions in question. To increase the reliability of radionuclide mapping it is suggested to use analysis of distribution of half-life values estimated for pixels of image zone(s) pointed by a special mask. [ABSTRACT FROM AUTHOR]

The paper presents systematic studies on the vertical profiles of Po, an important decay product of U, in soils along coastal Kerala. Soil samples collected from different depth intervals 0-10, 10-20, 20-30 cm were analyzed for Po activity concentration by radiochemical methods. The activity Po in soil samples were counted using a ZnS(Ag) alpha scintillation counting system. The mean values of activity concentrations of Po in soil of various depths were found to be 8.66, 5.63 and 4.95 Bq kg for depth intervals of 0-10, 10-20 and 20-30 cm, respectively. The overall activity concentration of Po in soil was found to vary from 2.26 ± 0.19 to 14.02 ± 0.12 Bq kg with a mean value of 6.43 Bq kg. Maximum activity concentration was found in soil samples of Kollam region with the mean value of 10.08 ± 0.92 Bq kg. The activity of Po was found to be comparatively high in surface soil. The variation of Po activity concentration with organic matter contents was studied.Polonium activity concentration was found to increase with increasing organic matter content. [ABSTRACT FROM AUTHOR]

In order to investigate the possible influence of metallic environment on the alpha decay process, we have measured the Sm activities in the hosts of metal samarium and SmO . The Sm half-life was found to be (1.06±0.01)×10 y in metal samarium and (1.07±0.01)×10 y in SmO , respectively. No significant change has been observed within the experimental uncertainty. The absolute half-life presented here is consistent with the recommended value. [ABSTRACT FROM AUTHOR]

In this work, a Monte Carlo (MC) simulation model is established to accurately characterize a phoswich beta-gamma coincidence detector system. This model can be easily used to predict the beta-gamma coincidence efficiencies of xenon radioisotopes at various stable xenon concentrations in the counting cell. The results demonstrate that there is a significant inverse correlation between beta-gamma coincidence efficiency and stable xenon concentration. The influence of stable xenon concentration on beta-gamma coincidence counting efficiency has been investigated for each individual xenon radioisotope. The results indicate that the effect of stable xenon concentration on beta-gamma coincidence efficiency depends on the xenon radioisotope and its decay modes. The coincidence efficiency of Xe with 31.0-keV X-ray decay mode is the most affected one; and then followed by Xe, Xe with 81.0-keV gamma-ray decay mode, Xe and finally Xe. The study also indicates that the gamma absorption by xenon gas plays more of a role in the decrease of beta-gamma coincidence efficiency for Xe and Xe, and that the conversion electron spectrum shifting and broadening plays more of a role in the reduction of beta-gamma coincidence efficiency for the metastable radioxenon of Xe and Xe. [ABSTRACT FROM AUTHOR]

We present a calculation of the coupling constant of f0→ργ and a0→ργ decays from the point of view of the light cone QCD sum rules. We estimate the coupling constants gf0ργ, which are an essential ingredient in the analysis of physical processes involving the isoscalar f0(980) and the isovector a0(980) mesons. [ABSTRACT FROM AUTHOR]

An analysis of the entire body of data on the intensities of two-step gamma cascades studied in thermal-neutron capture for more than 50 nuclei from the range 27 ≤ A ≤ 199 suggests that such processes should be described in terms of model concepts that are much more involved than those currently adopted by experimentalists. According to the results of this analysis, models of relevant parameters, such as the density of excited levels and radiative strength functions for dipole gamma transitions, should take into account more explicitly the coexistence and interaction of quasiparticle and phonon interactions. A direct inclusion of the idea that a second-order phase transition occurs and affects not only level densities but also radiative strength functions for dipole transitions may prove to be necessary. These conclusions concern primarily the excitation-energy region below a value of about 0.5 Bn.© 2005 Pleiades Publishing, Inc. [ABSTRACT FROM AUTHOR]

A new measurement of the200Fr a-decay half-life, with improved accuracy compared to previous measurements, has been carried out at the Isolde-CERN on-line mass separator. A half-life of 49(4) ms has been obtained, which is substantially different from earlier literature values. For the196At daughter decay, a half-life of 389(54) ms and an a branching ratioba = 94(5)% were measured. In addition, the half-lives of201, 203, 205Fr and197,199At are reported. [ABSTRACT FROM AUTHOR]

Detailed alpha-decay studies have been performed for the neutron-deficient isotopes 191At and 193At. The nuclei were produced in fusion-evaporation reactions of 54Fe and 56Fe ions with a 141Pr target. The fusion products were separated in-flight using a gas-filled recoil separator and implanted into a position-sensitive silicon detector. The isotopes were identified using position, time and energy correlations between the implants and subsequent alpha-decays. Three alpha-decaying states were identified for 193At and two for 191At. The spin and parity of the initial states in the astatine isotopes were deduced based on unhindered alpha-decays to states in the bismuth daughter nuclei. In both astatine isotopes the 1/2+ intruder state was determined to be the ground state and a 7/2- state to be the first-excited state. In 193At the alpha-decay of the 13/2+ state was observed in coincidence with a previously known gamma-ray transition from the 13/2+ state in the corresponding daughter nucleus 189Bi. In 187Bi and 189Bi low-lying 7/2- states were observed for the first time via alpha-decay of the mother nuclei. [ABSTRACT FROM AUTHOR]

Heavy-ion fusion reactions48Ca +204Pb and44Ca +208Pb leading to the same compound nucleus252No* were run in attempts to produce new neutron-deficient spontaneous-fission isotopes of249,250No using the electrostatic separator VASSILISSA. Production cross-sections for the spontaneous-fission activities with the half-lives 5.6 and 54 μs observed in these reactions are compared with the measured ones for the well-known isotopes of251 - 255No formed in the heavy-ion fusion reactions48Ca +206Pb and48Ca +208Pb. The obtained excitation functions for the reaction products formed after the evaporation of 1-4 neutrons from the corresponding compound No nuclei have been compared with similar data obtained earlier and results of statistical model calculations. [ABSTRACT FROM AUTHOR]

The experimental decay properties of the (21+) isomer in 94Ag are briefly discussed. [ABSTRACT FROM AUTHOR]

A new determination equipment combined with the time interval analysis (TIA) has been developed for the simultaneous determination of concomitant alpha–emitting nuclides, such as Pu, Am, Cm and natural alpha–emitters in dust samples. This discrimination technique for the determination of artificial alpha–nuclides is based on the selective subtraction of natural alpha–nuclides contribution to the total pulses by analysing the time interval distributions due to the successive alpha- and beta decay events within millisecond or microsecond orders. [ABSTRACT FROM AUTHOR]

Neutron-deficient uranium isotopes were studied via α spectroscopic methods. A low-lying α-decaying isomeric state was found in 218U. The new isomeric state was assigned spin and parity Iπ=8+. The isomer decays by α emission with an energy E = 10678(17)keV and with a half-life T1/2 = (0.56+0.26-0.14)ms. The known alpha-decay properties of the ground state of 218U was measured with improved statistics. The ground-state α-decay has an energy E = 8612(9)keV and a half-life T1/2 = (0.51+0.17-0.10)ms. [ABSTRACT FROM AUTHOR]

Alpha-decay properties of the isotope 191At were investigated for the first time and the decay properties of 193At and 195At were studied with improved accuracy. The nuclei were produced in fusion-evaporation reactions of 54Fe and 56Fe ions with 141Pr and 142Nd targets. The fusion products were separated in-flight using the gas-filled recoil separator RITU and implanted into a position-sensitive silicon detector. The isotopes were identified using position, time and energy correlations between the implants and subsequent alpha decays. New information concerning the low-lying states in the corresponding alpha-decay daughter nuclei 187Bi, 189Bi and 191Bi was also gained using alpha-gamma coincidences. [ABSTRACT FROM AUTHOR]

Neutron-deficient α-decaying nuclei have been produced using fusion-evaporation reactions. A gas-filled recoil separator was used to separate the fusion products from the scattered beam. The activities were implanted in a position sensitive silicon detector. The isotopes were identified using spatial and time correlations between implants and decays. During ten years of operation time about twenty new α-decaying isotopes have been identified in the translead region. In addition numerous α-decay studies have been performed on already known isotopes yielding much improved precision for the measured decay properties. An overview of the α-decay studies performed for the translead nuclei employing the gas-filled recoil separator will be given. [ABSTRACT FROM AUTHOR]