<Superscript>210</Superscript>Pb and <Superscript>210</Superscript>Po in fossil fuel combustion at the Šoštanj thermal power plant (Slovenia)

The main aim of the present study was to evaluate ²¹⁰Pb and ²¹⁰Po emissions from the ?o?tanj TPP and to evaluate their mass balance in unit 4. Samples of coal, fly ash, slag and flue gases were analysed for ²¹⁰Pb and ²¹⁰Po content. The results showed that these radionuclides are mostly concentrated in ash (71% and 81% for ²¹⁰Pb and ²¹⁰Po, respectively). Only a small part of the input activity was detected in flue gases. The activities of ²¹⁰Pb and ²¹⁰Po in unit 4 were from 1.1 to 2.7 Bq m^?3 and from 0.37 to 0.56 Bq m^?3, respectively. The mass balance of the two radionuclides in unit 4 show only 6 and 10% differences between the annual activities of the input and output samples.     

<Superscript>210</Superscript>Pb and <Superscript>210</Superscript>Po determination in environmental samples using liquid scintillation counting and alpha spectrometry

A simple radiochemical procedure has been developed to determine ²¹⁰Pb and ²¹⁰Po in environmental samples from the same matrix. Sediment samples are decomposed by leaching with mineral acids or by microwave digestion, while water samples are pre-concentrated. One part of the resulting solution, spiked with ²⁰⁹Po, is used for ²¹⁰Po determination by spontaneous deposition onto nickel disks (α-spectrometry). The other part is assayed for ²¹⁰Pb, separating the Pb either by anion-exchange (sediment samples), or by solvent extraction (water samples). The ²¹⁰Pb source is finally prepared by precipitation as oxalate and the chemical recovery determined by gravimetry. The ²¹⁰Pb activity concentration is determined by liquid scintillation. A standard sediment sample supplied by IAEA and spiked water samples were analysed to check the procedure. The ²¹⁰Pb and ²¹⁰Po measurements agreed well with the certifications, deviations being less than 10%. The mean recoveries for Pb and Po were (70±12)% and (77±8%) for sediments, and (70±10)% and (81±7)% for waters, respectively.     

Dissolved 210Po and 210Pb in Guarani aquifer groundwater,Brazil

The huge Guarani aquifer located in the South American continent is a very important resource for the region, and its drinking water quality has been investigated according to international standards, inclusive radiological parameters. This paper describes ²¹⁰Po and ²¹⁰Pb activity concentration data in groundwater samples collected at the Brazilian portion of Guarani aquifer, that is characterized by a great variability of temperature (18–70 °C), pH (4.0–9.9), sodium content (0.3–322 mg/l), bicarbonate content (0.1–318 mg/l), etc. Non-expensive alpha counting following some radiochemical steps for extracting and depositing dissolved ²¹⁰Po was used. The results of the measurements for samples collected in duplicate yielded a maximum ²¹⁰Po activity concentration of 3.7 mBq/L and a maximum ²¹⁰Pb activity concentration of 6.7 mBq/l, that are values greatly lower than the guidance level of 0.1 Bq/l established by the WHO for their presence in drinking water. The high sensitivity of the method allowed its applicability on the identification of complexes geochemical and hydrogeological processes occurring in Guarani aquifer as well on the evaluation of the drinking water quality in terms of dose calculations.     

Sedimentological study of a lagoon through natural radioactivity and <Superscript>137</Superscript>Cs determinations

Profiles of artificial fallout (such as ¹³⁷Cs) and natural radioactivity radionuclides in sediment cores are useful tools to study sedimentological properties of different aquatic environments as well as to evaluate average sedimentation rates. In the Portil lagoon, a small natural reservoir located in Huelva province (southwest of Spain), and through the analysis of ²¹⁰Pb, ²²⁶Ra, ¹³⁷Cs, ²³⁸U and ²¹⁰Po vertical profiles in sediment cores, it is shown how the accumulative or transport character of the collection zones may be inferred. In the accumulation zone of the lagoon the influence of focusing effects has been analysed and an average sedimentation rate has been determined through ²¹⁰Pb in one sediment core. This ²¹⁰Pb-sedimentation rate is consistent with sediment dating based on the ¹³⁷Cs data.     

Observation of daily and annular variations in the <Superscript>214</Superscript>Po half-life

Results of the analysis of a time series of values of the half-life (τ) of the ²¹⁴Po nucleus with a different time step obtained from the TAU-1 (354 days) and TAU-2 (973 days) installations are presented. The annual variation with an amplitude of (9.8 ± 0.6) × 10^?4 and daily variations in the solar, lunar, and sidereal times with amplitudes of (5.3 ± 0.3) × 10^?4, (6.9 ± 2.0) × 10^?4, and (7.2 ± 1.2) × 10^?4, respectively, are found in the series of τ values. It is shown that variations in microclimatic parameters cannot be a cause of τ variations.     

Polonium in cigarette smoke and radiation exposure of lungs

Polonium (²¹⁰Po), the most volatile of naturally-occurring radionuclides in plants, was analysed in three common brands of cigarettes produced in Portugal. The analyses were carried out on the unburned tobacco contained in cigarettes, on the ashes and butts of smoked cigarettes and on the mainstream smoke. ²¹⁰Po in tobacco displays concentrations ranging from 3 to 37 mBq g⁻¹, depending upon the cigarette brand. The ²¹⁰Po activity remaining in the solid residue of a smoked cigarette varied from 0.3 to 4.9 mBq per cigarette, and the ²¹⁰Po in the inhaled smoke varied from 2.6 to 28.9 mBq. In all brands of cigarettes tested, a large fraction of the ²¹⁰Po content is not inhaled by the smoker and it is released into the atmosphere. Part of it may be inhaled by passive smokers. Depending upon the commercial brand and upon the presence or absence of a filter in the cigarette, 5 to 37 % of the ²¹⁰Po in the cigarette can be inhaled by the smoker. Taking into account the average ²¹⁰Po in surface air, the smoker of one pack of twenty cigarettes per day may inhale 50 times ²¹⁰Po than a non smoker. Cigarette smoke contributes with 1.5 % to the daily rate of ²¹⁰Po absorption into the blood, 0.39 Bq d⁻¹, and, after systemic circulation it gives rise to a whole body radiation dose in the same proportion. However, in the smoker the deposition of ²¹⁰Po in the lungs is much more elevated than normal and may originate an enhanced radiation exposure. Estimated dose to the lungs is presented and radiobiological effects of cigarette smoke are discussed.     

Po and Pb concentration of cigarettes traded in Hungary and their estimated dose contribution due to smoking

It is known that tobacco leaves may contain ²¹⁰Pb and ²¹⁰Po in significant concentrations. The cumulative alpha-radiation dose due to the radioactive content of inhaled cigarette smoke and the increasing number of lung cancer cases explain the importance of the investigation. The present study investigated the activity concentrations of these two radionuclides in 29 Hungarian cigarette samples. The relation between ²¹⁰Po/²¹⁰Pb activity and nicotine/tar content of these cigarettes was also examined. ²¹⁰Po was determined by alpha spectrometry using a PIPS detector after chemical leaching and spontaneous deposition of ²¹⁰Po on a high nickel-content (25%) stainless steel disk. The ²¹⁰Pb activity was calculated from the ²¹⁰Po originated from the decay of ²¹⁰Pb after a waiting period of eight months. The ²¹⁰Po activity concentrations of the measured types of cigarettes ranged from 10.0 to 33.5 mBq/cigarette, and the activity of ²¹⁰Pb varied from 9.6 to 32.5 mBq/cigarette. The average annual committed effective dose is estimated to be $185.6\pm 70.6\mathrm{\mu }\mathrm{Sv}/\mathrm{y}$ and $58.7\pm 22.7\mathrm{\mu }\mathrm{Sv}/\mathrm{y}$ due to cigarette smoking (20 cigarettes/day) for ²¹⁰Po and ²¹⁰Pb, respectively.     

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.     

Super-allowed α decay above doubly-magic <Superscript>100</Superscript>Sn and properties of <Superscript>104</Superscript>Te = <Superscript>100</Superscript>Sn ⊗ α

α-decay half-lives for ^{104, 105, 106}Te and ^{108, 109, 110}Xe close above the doubly-magic ¹⁰⁰Sn are calculated from systematic double-folding potentials. The derived α preformation factors are compared to results for ^{212, 213, 214}Po and ^{216, 217, 218}Rn above the doubly-magic ²⁰⁸Pb. α-decay energies of Q _α = 5.42±0.07MeV and 4.65±0.15MeV are predicted for ¹⁰⁴Te and ¹⁰⁸Xe; the corresponding half-lives are T _1/2 ≈ 5ns for ¹⁰⁴Te and of the order of 60μs for ¹⁰⁸Xe. Additionally, the properties of rotational bands in ¹⁰⁴Te are analyzed, and the first excited 2⁺ state in ¹⁰⁴Te is predicted at E _x = 650±40keV; it decays preferentially by γ emission with a reduced transition strength of 10 Weisskopf units to the ground state of ¹⁰⁴Te and with a minor branch by α emission to the ground state of ¹⁰⁰Sn.     

Double-beta decay of <Superscript>150</Superscript>Nd to the first 0<Superscript>+</Superscript> excited state of <Superscript>150</Superscript>Sm

Two-neutrino-double-beta decay of ¹⁵⁰Nd to the first 0⁺ excited state in ¹⁵⁰Sm is investigated with a 400-cm³ low-background HPGe detector. Data analysis for 11320.5 h shows an excess of events at 333.9 and 406.5 keV. This allows us to estimate the half-life of the investigated process as [1.4 _?0.2 ^+0.4 ±0.3(syst.)]×10²⁰ yr.     

Double beta decay of <Superscript>150</Superscript>Nd to the First 0<Superscript>+</Superscript> excited state of <Superscript>150</Superscript>Sm

Two neutrino double beta decay of ¹⁵⁰Nd to the first 0⁺ excited state in ¹⁵⁰Sm is investigated with the 400 cm³ low-background HPGe detector. Data analysis for 11320.5 h shows the excess of events at 333.9 and 406.5 keV. This makes it possible to estimate the half-life of the investigated process as [1.4 _?0.2 ^+.04 (stat)±0.3(syst)]×10²⁰yr.     

210Po in popular medicinal herbs from Poland

Herbs are an important part of traditional medicine in Poland. Therefore, the aim of this study was the determination of polonium ²¹⁰Po in 48 selected medicinal herb samples from the Polish market. The activity concentrations of ²¹⁰Po were measured using alpha spectrometry. The activity concentration of ²¹⁰Po was in the range from 0.3?±?0.1 to 28.2?±?0.4 Bq kg^–1. The obtained results were compared with corresponding studies conducted worldwide. A higher ²¹⁰Po activity concentration was observed in the above-ground part of plants. The obtained results show that the highest ²¹⁰Po activity concentration was observed in evergreen plants and winter-hardy plants. Yet even infusions with 2 g of the most contaminated herbs examined were considered to be radiologically safe.     

Electron-impact ionization and dissociation of C<Subscript>2</Subscript>D<Superscript>+</Superscript>

Absolute cross sections for electron-impact single ionization, dissociative excitation and dissociative ionization of the ethynyl radical ion (C₂D⁺)^+) have been measured for electron energies ranging from the corresponding reaction thresholds to 2.5 keV. The animated crossed electron-ion beam experiment is used and results have been obtained for the production of C₂D²⁺, C²⁺, C₂⁺_2^+ , CD⁺, C⁺ and D⁺. The maximum of the cross section for single ionization is found to be (2.01 ± 0.02) × 10^-17 cm², at the incident electron energy of 105 eV. Absolute total cross sections for the various singly charged fragments production are observed to decrease by a factor of almost three, from the largest cross-section measured for C⁺, over C₂⁺_2^+ and CD⁺ down to that of D⁺. The maxima of the cross sections are obtained to be (14.5 ± 0.5) × 10^-17 cm² for C₂⁺_2^+, (12.1 ± 0.1) × 10^-17 cm² for CD⁺, (27.7 ± 0.2) × 10^-17 cm² for C⁺ and (11.1 ± 0.8) × 10^-17 cm² for D⁺. The smallest cross section is measured to be (1.50 ± 0.04) × 10^-18 cm² for the production of the doubly charged ion C²⁺. Individual contributions for dissociative excitation and dissociative ionization are determined for each singly-charged product. The cross sections are presented in closed analytic forms convenient for implementation in plasma simulation codes. Kinetic energy release distributions of dissociation fragments are seen to extend from 0 to 6 eV for the heaviest fragment C₂⁺_2^+, up to 11.0 eV for CD⁺, 14.2 eV for C⁺ and 11.2 eV for D⁺ products.     

Absolute cross sections and kinetic energy release distributions for electron-impact ionization and dissociation of CD<Superscript>+</Superscript><Subscript>4</Subscript>

Absolute cross sections for electron-impact dissociative excitation and ionization of CD⁺ ₄ leading to formation of ionic products (CD²⁺ ₄, CD⁺ ₃, CD⁺ ₂, CD⁺, C⁺, D⁺ ₃, D⁺ ₂, and D⁺) have been measured. The animated crossed-beams method is applied in the energy range from the reaction threshold up to 2.5 keV. Around 100 eV, the maximum cross sections are found to be (3.8±0.2) ×10^-19 cm²,  cm², (7.1±0.8) ×10^-17 cm², (9.0±0.8) × 10^-17 cm² and (3.7±0.4) ×10^-17 cm² for the heavy carbonaceous ions CD²⁺ ₄, CD⁺ ₃, CD⁺ ₂, CD⁺ and C⁺ respectively. For the light fragments, D⁺ ₃, D⁺ ₂, and D⁺, the cross sections around the maximum are found to be (5.0±0.6) ×10^-19 cm², (1.7± 0.2) ×10^-17 cm² and (10.6±1.0) ×10^-17 cm², respectively. The cross sections are presented in closed analytic forms convenient for implementation in plasma simulation codes. The analysis of ionic product velocity distributions allows determination of the kinetic energy release distributions which are seen to extend from 0 to 9 eV for heavy fragments, and up to 14 eV for light ones. The comparison of present energy thresholds and kinetic energy release with available published data gives information about states contributing to the observed processes. Individual contributions for dissociative excitation and dissociative ionization are determined for each detected product. A complete database including cross sections and energies is compiled for use in fusion application.     

Kinetics of radiation-induced segregation in 12Cr-MoWSiVNbB steel after Ni<Superscript>++</Superscript> and He<Superscript>+</Superscript> ion irradiation

Ferritic-martensitic 12Cr-MoWSiVNbB (EP-823) steel was irradiated with 7 MeV Ni⁺⁺ ions within fluence interval 5 × 10¹⁸−5.4 × 10¹⁹ ions/m² and with 30 and 70 keV He⁺ ions within fluence interval 10²⁰–10²¹ ions/m² at 500°C. Results from a comparative analysis of Cr and Si radiation-induced segregation profiles near the surface are presented. Dependence of the amount of surface segregation on damage dose, displacement generation rate, and radiation-induced point defects concentration is established.     

I. Electron-impact ionization and dissociation of C<Subscript>2</Subscript>H<Stack><Subscript>2</Subscript><Superscript>+</Superscript></Stack> and C<Subscript>2</Subscript>D<Stack><Subscript>2</Subscript><Superscript>+</Superscript></Stack>

Absolute cross-sections for electron-impact ionization and dissociation of C₂H₂⁺ and C₂D₂⁺ have been measured for electron energies ranging from the corresponding thresholds up to 2.5 keV. The animated crossed beams experiment has been used. Light as well as heavy fragment ions that are produced from the ionization and the dissociation of the target have been detected for the first time. The maximum of the cross-section for single ionization is found to be (5.56 ± 0.03)× 10^-17 cm² around 140 eV. Cross-sections for dissociation of C₂ H₂⁺ (C₂D₂⁺) to ionic products are seen to decrease for two orders of magnitude, from C₂D⁺ (12.6 ± 0.3) × 10^-17 cm² over CH⁺(9.55 ± 0.06) × 10^-17 cm², C⁺ (6.66 ± 0.05) × 10^-17 cm², C₂⁺ (5.36 ± 0.27) × 10^-17 cm², H⁺ (4.73 ± 0.29) × 10^-17 cm² and CH₂⁺ (4.56 ± 0.27) × 10^-18 cm² to H₂⁺ (5.68 ± 0.49) × 10^-19 cm². Absolute cross-sections and threshold energies have been compared with the scarce data available in the literature.     

In-beam γ-ray spectroscopy of <Superscript>190</Superscript>Po: First observation of a low-lying prolate band in Po isotopes

Gamma rays from excited states of ¹⁹⁰Po have been observed using the Jurosphere Ge-detector array coupled to the RITU gas-filled separator. They were associated with a collective band which from spin 4 onwards resembles the prolate rotational bands known in the isotones ¹⁸⁸Pb and ¹⁸⁶Hg. This indicates that in ¹⁹⁰Po the prolate configuration becomes yrast above I = 2. The experimental results are interpreted in a two-band mixing calculation and are in agreement with α-decay data and potential energy surface calculations. Received: 10 January 2003 / Accepted: 19 February 2003 / Published online: 7 May 2003     

Double-beta decay of <Superscript>150</Superscript>Nd to the first 0<Superscript>+</Superscript> excited state of <Superscript>150</Superscript> Sm: Current state

Two-neutrino double-beta decay of ¹⁵⁰Nd to the first 0⁺ excited state in ¹⁵⁰Sm is investigated with the 400-cm³ low-background HPGe detector. Preliminary data analysis for 6843 h shows an excess of events at 333.9 and 406.5 keV. If this excess is assigned to the investigated transition, then its half-life can be estimated at [1.2 _?0.3 ^+0.5 ±0.4(syst.)]×10²⁰ yr.