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Introduction/Aim: α particle emitting bismuth (212Bi) as decay product of 212Pb-labeled pharmaceuticals has been effective in targeted α particle therapy (TAT). Estimating the contribution of 212Bi...

In the present work, Computational Fluid Dynamics (CFD) code has been used to simulate the behaviour of aerosols and decay products of 222Rn/220Rn in indoor environments. The code has been incorporated with simulation modules describing relevant physical processes governing the aerosol and decay product dynamics such as particle deposition, gravitational settling, thermophoresis, coagulation and size dependent attachment of decay products to aerosol. Subsequently, reliability and consistency of the CFD code has been evaluated and validated by comparing simulated results with analytical and simulation results of well-known cases reported in literature. Comparison showed a good agreement within ± 3.5%.

Experimental nuclear structure and decay data are evaluated for all of 15 known nuclides of mass 123 (Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, I, Xe, Cs, Ba, La, Ce). For each nuclide, detailed evaluated spectroscopic information is presented in each reaction and decay, and the best values combining all available data are recommended for level properties, γ and β radiations, and other spectroscopic properties. No excited states have been identified in 123Ru, 123Rh and 123Pd. For 123Ag, the long-predicted 1/2− β-emitting isomer has been identified at 60-keV by 2019Ch24 recently, resolving unknown excitation energies in the level scheme that was previously available only from isomeric decays of two isomers (202 ns and 393 ns) with the position and spin-parity of the former remaining unknown. Significant discrepancies exist between data on high-spin sequences based on 11/2(−) isomer in 123Cd (2002Hw01 and 2016Re05), which needs to be resolved with further experimental investigation. In 123Cs, the 114-ns isomer as the πg9/2 bandhead proposed at 231.6+x by 2000Gi12 has been resolved by 2004Si26 and 2004Si27 to be the 328-keV level that is proposed by 2000Gi12 as a separate level. Excited states in 123La and 123Ce have only been studied via (HI, xnγ) reactions, with their base levels and thus excitation energies remaining unknown. The β− decay schemes for daughter nuclide 123Cd, 123In and 123Sn and the e decay schemes for 123Xe, 123Cs and 123Ba are considered incomplete due to large gaps between the highest observed excited levels and the Q-values. 123Sn, 123Sb, 123Te and 123I are the most extensively studied nuclides via various reactions and decays. This work supersedes earlier full evaluations of A=123 by 2004Oh11, 1993Oh12, 1980Ta02 and 1972Au10.

Radioactive strontium is a nuclear fission decay product found in industrial products and nuclear waste and is released during nuclear accidents. Current urine radiostrontium separation methods often are based on the use of Sr resin columns or cartridges (Eichrom Technologies). Most of these analytical methods use stable Sr as a tracer, with subsequent Sr recovery. The gravimetric recovery method requires 120 times more stable Sr than does the inductively coupled plasma mass spectrometry method described here. This difference can affect cartridge performance especially with aging cartridges.

Attosecond pump-attosecond probe spectroscopy is becoming possible due the development of sub-femtosecond free electron laser (FEL) pulses as well as intense high-order harmonic generation-based attosecond sources. Here we investigate theoretically whether these developments can provide access to direct time-resolved measurement of Auger decay through detection of the total yield of an ionic decay product, in analogy to the photodissociation product detection in femtochemistry. We show that the ion yield based measurement is generally possible and in the case of the inner-valence hole decay can be background-free. Extensive first principles calculations are used to optimise the probe photon energies for a variety of prototypical systems.

U–Pb geochronology of calcite by laser-ablation inductively coupled plasma mass spectrometry (LA-ICPMS) is an emerging field with potential to solve a vast array of geologic problems. Because of low levels of U and Pb, measurement by more sensitive instruments, such as those with multiple collectors (MCs), is advantageous. However, whereas measurement of traditional geochronometers (e.g., zircon) by MC-ICPMS has been limited by detection of the daughter isotope, U–Pb dating of calcite can be limited by detection of the parent isotope if measured on a Faraday detector. The Nu P3D MC-ICPMS employs a new detector array to measure all isotopes of interest on Daly detectors. A new method, described herein, utilizes the low detection limit and high dynamic range of the Nu P3D for calcite U–Pb geochronology and compares it with traditional methods. Data from natural samples indicate that measurement of 238U by Daly is advantageous at count rates < 30 000; this includes samples low in U or those necessitating smaller spots. Age precision for samples run in this mode are limited by 207Pb counts and the maximum U ∕ Pbc. To explore these limits – i.e., the minimum U, Pb, and U ∕ Pb ratios that can be measured by LA-ICPMS – a model is created and discussed; these models are meant to serve as a guide to evaluate potential candidate materials for geochronology. As an example, for samples necessitating a < 1 Ma uncertainty, a minimum of ∼ 10 ppb U is needed at a spot size of 100 µm and rep rate of 10 Hz; absolute uncertainty scales roughly with U concentration.

The fission reactions of 238U induced by D-T neutrons were investigated by neutron activation technique and low-background HPGe-γ spectrometer. The half-life was used to identify the possible daughter nuclide. The fission cross-sections of 238U(n,f)89Rb reaction induced at the neutron energy around 14 MeV, i.e., 14.1 ± 0.3, 14.5 ± 0.3 and 14.7 ± 0.3 MeV, were measured precisely. The neutron flux was monitored by accompanying α-particle of the T(d,n)4He reaction and the neutron energies were determined by the cross-section ratio of 90Zr(n,2n)89Zr to 93Nb(n,2n)92mNb reaction. The fission cross-sections of the 238U(n,f)89Rb reaction are 33.2 ± 2.1 mb, 32.2 ± 2.0 mb, and 32.6 ± 2.1 mb, corresponding to the above neutron energy points.

The analysis of radionuclides (RN) is of major concern in different fields like the environment, geosciences, the nuclear industry, and medical research. Inductively coupled plasma mass spectrometry (ICP-MS) is a valuable technique for rapid and highly sensitive analysis of RN in different types of samples. Incorporating collision–reaction cells (CRC) into ICP-MS instruments is a very attractive and elegant way to overcome spectral interferences, which affects the accuracy of measurements. This paper reviews the elemental and isotopic analysis of RN using CRC technology for different types of applications including environmental studies, the nuclear industry, forensics and biological applications. The various collision–reaction cell technologies implanted in the ICP-MS instruments, are described and discussed. The different strategies based on collision–reaction mechanisms for RN analysis described in the literature are detailed element by element, including actinides (U, Pu, Am, Cm and Np), fission products (Se, Sr, Mo, Zr, I, Cs, lanthanides) and a decay product of the uranium series (Ra).

In this paper, we describe a practical and convenient method to include the contribution of the ingrowth of radioactive progeny in dose assessments of the corresponding parent nuclides. This method modifies the dose coefficients (DCs) of parent nuclides by adding weighted DCs of the corresponding daughter nuclides to them. Based on the decay kinetics of serial nuclear transformations, the progeny weighting factors, with values between 0 and 1, are derived by analysis of the time-integrated activity of each nuclide in the (branched) decay chain headed by a parent nuclide. Using the electronic, nuclear-decay database of Publication 107 of the International Commission on Radiological Protection (ICRP 2008), DC weighting factors for annual dose assessments are calculated for all daughter radionuclides in the decay chains and are tabulated in this paper. Weighting factors based on integration periods other than one year, ranging from 1 h–70 years, are also provided (see the supplementary material). With a priori established weighting factors, dose assessments become significantly simplified by considering the decay kinetics of only the parent nuclides and by applying the modified DCs. This ensures that the ingrowth of progeny is taken into account realistically. In some cases, one requires a conservative estimate of the dose, for instance when dealing with issues of the clearance of materials under regulatory control. Therefore, we adapted the weighting-factor method to derive conservative DC weighting factors for dose evaluations. These values are calculated for various integration periods and compared with those from an existing method adopted by the Euratom Article 31 Group of Experts and by the International Atomic Energy Agency. Identical progeny weighting factors are obtained for long-lived parent radionuclides, whereas for short-lived parent radionuclides, the new method can yield significantly larger values. For example, the weighting factor of I-131 (daughter of parent Te-131) increases from 0.002 to 1.0 based on an integration period of 1 year. The progeny DC weighting factors, derived based on nuclear transformations in exit-only decay chains, may not always be suitable for use in radiological dose evaluations. For instance, when environmental removal pathways are dominant, the application of these weighting factors may have its limitations. This paper, therefore, provides guidance on the proper selection and application of weighting factors.

An alert indicating the formation of salt deposits in the pipelines of oil and gas production complexes reduces the financial losses associated with the removal of these deposits and the loss of production. A method of taking into account the presence of the native radionuclide 232Th and its decay product 208Tl in the deposits is proposed for performing radiation diagnostics of pipelines. The appearance of the deposits is identified according to the 2.614 MeV γ-rays. The thickness of the deposits is determined according to the attenuation of the γ-rays from an external thorium dioxide source placed on the outer surface of a pipe. Calculations confirmed the presence of 1–2 mm thick deposits with probability 0.9 and a false positive rate of 0.01 in 1 h measurements with background 3 counts/sec. A 232Th-based external source with activity 105 and 106 Bq makes it possible to determine deposit thicknesses 2.5–3 and 1–2 mm, respectively, with measurement time 1 h and error about 15%.

Various geophysical models have shown that Ar, a natural decay product of 40K, is depleted in Earth’s main reservoirs (i.e., continental crust, atmosphere, and silicate mantle). This indicates that...

Samarium-153 (153Sm) is a highly interesting radionuclide within the field of targeted radionuclide therapy because of its favorable decay characteristics. 153Sm has a half-life of 1.93 d and decays into a stable daughter nuclide (153Eu) whereupon β− particles [E = 705 keV (30%), 635 keV (50%)] are emitted which are suitable for therapy. 153Sm also emits γ photons [103 keV (28%)] allowing for SPECT imaging, which is of value in theranostics. However, the full potential of 153Sm in nuclear medicine is currently not being exploited because of the radionuclide's limited specific activity due to its carrier added production route. In this work a new production method was developed to produce 153Sm with higher specific activity, allowing for its potential use in targeted radionuclide therapy. 153Sm was efficiently produced via neutron irradiation of a highly enriched 152Sm target (98.7% enriched, σth = 206 b) in the BR2 reactor at SCK CEN. Irradiated target materials were shipped to CERN-MEDICIS, where 153Sm was isolated from the 152Sm target via mass separation (MS) in combination with laser resonance enhanced ionization to drastically increase the specific activity. The specific activity obtained was 1.87 TBq/mg (≈ 265 times higher after the end of irradiation in BR2 + cooling). An overall mass separation efficiency of 4.5% was reached on average for all mass separations. Further radiochemical purification steps were developed at SCK CEN to recover the 153Sm from the MS target to yield a solution ready for radiolabeling. Each step of the radiochemical process was fully analyzed and characterized for further optimization resulting in a high efficiency (overall recovery: 84%). The obtained high specific activity (HSA) 153Sm was then used in radiolabeling experiments with different concentrations of 4-isothiocyanatobenzyl-1,4,7,10-tetraazacyclododecane tetraacetic acid (p-SCN-Bn-DOTA). Even at low concentrations of p-SCN-Bn-DOTA, radiolabeling of 0.5 MBq of HSA 153Sm was found to be efficient. In this proof-of-concept study, we demonstrated the potential to combine neutron irradiation with mass separation to supply high specific activity 153Sm. Using this process, 153SmCl3 suitable for radiolabeling, was produced with a very high specific activity allowing application of 153Sm in targeted radionuclide therapy. Further studies to incorporate 153Sm in radiopharmaceuticals for targeted radionuclide therapy are ongoing.

The parameters of the emission Mossbauer spectra of PbTe using the 119mSn daughter isotope with different parent nuclei 119mmSn, 119Sb, and 119mTe are compared. This comparison makes it possible to identify impurity tin atoms in both lead-telluride sublattices. It is found that the ratio of tin concentrations in different sublattices depends on the time after source preparation.

Purpose Technetium-99m (99m Tc) is the radioisotope most widely used in diagnostic nuclear medicine. It is readily available from 99 Mo/99m Tc generators as the β- decay product of the 99 Mo (Tf = 66 h) parent nuclide. This latter is obtained as a fission product in nuclear reactors by neutron-induced reactions on highly enriched uranium. Alternative production routes, such as direct reactions using proton beams on specific target materials [100 Mo(p,2n)99m Tc], have the potential to be both reliable and relatively cost-effective. However, results showed that the 99m Tc extracted from proton-bombarded 100 Mo-enriched targets contains small quantities of several Tc radioisotopes (93m Tc, 93 Tc, 94 Tc, 94m Tc, 95 Tc, 95m Tc, 96 Tc, and 97m Tc). The aim of this work was to estimate the dose increase (DI) due to the contribution of Tc radioisotopes generated as impurities, after the intravenous injection of four radiopharmaceuticals prepared with cyclotron-produced 99m Tc (CP-99m Tc) using 99.05% 100 Mo-enriched metallic targets. Methods Four 99m Tc radiopharmaceuticals (pertechnetate, sestamibi (MIBI), hexamethylpropylene-amine oxime (HMPAO) and disodium etidronate (HEDP)) were considered in this study. The biokinetic models reported by the International Commission on Radiological Protection (ICRP) for each radiopharmaceutical were used to define the main source organs and to calculate the number of disintegrations per MBq that occurred in each source organ (Nsource ) for each Tc radioisotope present in the CP-99m Tc solution. Then, target organ equivalent doses and effective dose were calculated for each Tc radioisotope with the OLINDA/EXM software versions 1.1 and 2.0, using the calculated Nsource values and the adult male phantom as program inputs. Total effective dose produced by all Tc isotopes impurities present in the CP-99m Tc solution was calculated using the fraction of total activity corresponding to each radioisotope and compared with the effective dose delivered by the generator-produced 99m Tc. Results In all cases, the total effective DI of CP-99m Tc radiopharmaceuticals calculated with either versions of the OLINDA software was less than 10% from 6 up to 12 h after EOB. 94m Tc and 93m Tc are the Tc radioisotopes with the highest concentration in the CP-99m Tc solution at EOB. However, their contribution to DI 6 h after EOB is minimal, due to their short half-lives. The radioisotopes with the largest contribution to the effective DI are 96 Tc, followed by 95 Tc and 94 Tc. This is due to the types of their emissions and relatively long half-lives, although their concentration in the CP-99m Tc solution is five times lower than that of 94m Tc and 93m Tc at the EOB. Conclusions The increase in the radiation dose caused by other Tc radioisotopes contained in CP-99m Tc produced as described here is quite low. Even though the concentrations of the 94 Tc and 95 Tc radioisotopes in the CP-99m Tc solution exceed the limits established by the European Pharmacopoeia, CP-99m Tc radiopharmaceuticals could be used in routine nuclear medicine diagnostic studies if administered from 6 to 12 h after the EOB, thus maintaining the effective DI within the 10% limit.

In the light of the recently observed XENON1T electronic recoil (ER) data, we investigate the possibility of constraining the parameter space of a generic fermionic warm dark matter (WDM), decaying into a standard model (SM) neutrino and a photon. The photon as a decay product, when produced inside the XENON1T chamber, interacts with an electron of a xenon (Xe) atom, leading to a contribution in the observed ER data. We add this dark matter (DM) induced signal over the standard background ($\rm B_0$) considered by the XENON1T collaboration and perform a $\chi^2$ fit against the XENON1T data to obtain the best-fit values of the DM decay width and the associated $95\%$ confidence level (C.L.) band for DM mass ($m_\chi$) varied in the range $2 - 60$ keV. Additionally, we have extended our analysis by including two other background models available in the literature and in each case, the corresponding limits on the DM decay width are estimated for DM mass ($m_\chi$) in the domain $2 - 18$ keV. By comparing the constraints, obtained by fitting the XENON1T data, with the upper limits arising from various existing astrophysical and cosmological observations, we find that, for the background model $\rm B_0$, a fair amount of the DM parameter space is allowed at $95\%$ C.L. for DM masses outside the range $3.5\,{\rm keV} \lesssim m_\chi \lesssim 8.5\,{\rm keV}$. However, in case of other two background models, reasonable parts of the DM parameter space are favoured at $95\%$ C.L. by all astrophysical data for all DM masses in the range $2 - 18$ keV., Comment: 9 pages, 4 figures; text modified, figures modified, current version matches with the version published in Phys.Dark Univ

Regional averages of radon, thoron, and associated decay product concentration are reported to be higher than their respective global averages in recent studies conducted in Indian Himalayan belt. The present study explores another region in Indian Himalayan belt by conducting measurements of radon, thoron, and decay product’s activity concentration in 92 dwellings of Bageshwar district. The year-long measurements were performed in all 3 seasons distinguishing dwellings as per their construction material. The average radon and thoron concentration for the study region was measured as 57 Bq/m3 and 66 Bq/m3, respectively. Analysis of the measured data in terms of seasonal effects and construction material led to well established inferences, i.e., higher concentration for mud houses and for winter season. In addition, the present study focuses on lesser probed statistical inferences. One of them is related to the appropriateness of frequency distribution function for the measured data and other dwells upon the correlation analysis of inter-related factors for high concentration cases. Three distribution functions (Lognormal, Weibull, and Gamma) were found to be following the trend of frequency distribution curve of the measured data. For mud houses in winter season, variations of radon/thoron concentration were attempted to correlate with mass/surface exhalation rate, emanation rate, and source term content. More than 80% of the dwellings of the study region were found to have gas and decay product’s concentration levels, higher than the respective global average values. However, these values were mostly within the reference levels for residential environments. Nevertheless, this region requires further studies to pinpoint the causes for elevated levels and suggest simple remedial modifications if required.

Ингибиторы трипсина являются анти питательными веществами, ограничивающими использование сои в пищевых и кормовых целях, что требует постоянного контроля за их содержанием. Установлены некоторые особенности «казеинового метода» определения активности ингибиторов трипсина в зерне сои. В результате исследований определено, что наиболее эффективной длиной волны для спектрофотометрического определения продуктов гидролиза казеина, количество которых характеризует активность ингибиторов, является 276 нм, а оптимальное количество экстракта белковой вытяжки, необходимой для проведения анализов, должно быть в пределах 0,35–0,40 мл. С учетом выявленных особенностей, установлена активность ингибиторов трипсина в зерне новых и перспективных сортов сои селекции ФГБНУ «ВНИИ сои»., Trypsin inhibitors are anti-nutritional substances that limit the use of soybean for food and feed purposes, so the constant control over their content is required.The studies have been conducted and some features of the “casein method” for determining the activity of trypsin inhibitors in soybean grain have been established. As a result of research, it was found that the most effective wavelength for spectrophotometric determination of casein decay products, the number of which characterizes the activity of inhibitors, is 276 nm, and the optimal extract amount of the protein extraction required for analysis should be within 0,35–0,40 ml. Having taken into consideration the identifi ed peculiarities, it has been determined the tripsin inhibitors` activity in soybeans of new and promising varieties of soy selection of the Federal State Budget Institution “VNII soi”., Естественные и технические науки, Выпуск 6 2020

The first ever search for $\alpha$ decays to the first excited state in Yb was performed for six isotopes of hafnium (174, 176, 177, 178, 179, 180) using a high purity Hf-sample of natural isotopic abundance with a mass of 179.8 g. For $^{179}$Hf, also $\alpha$ decay to the ground state of $^{175}$Yb was searched for thanks to the $\beta$-instability of the daughter nuclide $^{175}$Yb. The measurements were conducted using an ultra low-background HPGe-detector system located 225 m underground. After 75 d of data taking no decays were detected but lower bounds for the half-lives of the decays were derived on the level of $\lim T_{1/2}\sim 10^{15}-10^{18}$~a. The decay with the shortest half-life based on theoretical calculation is the decay of $^{174}$Hf to the first $2^+$ 84.3~keV excited level of $^{170}$Yb. The experimental lower bound was found to be $T_{1/2}\geq 3.3\times 10^{15}$ a., Comment: 19 pages, 7 figures, 7 tables

Radon-222 is inert radioactive gas with a half-life period of 3.8 days, it is a decay product of radium-226. Being escaped from minerals and underground waters into pore space of rocks and soil, it is transported to the surface by diffusion and advection and gone to the atmosphere. When modeling processes of atmosphere radon transport one sets value of radon flux from the surface, depending on contents of radium-226 in rocks and conditions of radon transport in soil, especially on soil porosity and humidity. The impact of radon turbulent transport in the atmospheric boundary layer (ABL) on radon flux density from the surface is estimated in this paper. It is shown that both for stationary state and for typical diurnal variations of the radon volumetric activity (VA) in the ABL, the correction to the radon flux density caused by its turbulent transport in the ABL is negligible (less than 1%) and doesn’t exceed measurement errors. Thus, when calculating radon VA in the ABL it is really possible to set an average value of the radon flux density on the surface as a boundary condition.

The alpha emission spectrum of electrodeposited thin film 232Th and depleted uranium sources, including the alpha emitting 232Th decay chain daughters and 238U daughter nuclide 234U, have been measured using a thin film 4H–SiC alpha detector. The energy resolution of this detector was proved suitable for the identification of many of the major characteristic alpha emissions associated with the 232Th daughter isotopes. The identification of the lower energy daughter isotopes made from the 4H–SiC detector measurements was confirmed using a silicon surface barrier detector. A depleted uranium source was fabricated using electrodeposition in a molten salt and the alpha spectrum was acquired with a 4H–SiC detector. The 234U/238U activity ratio and atomic enrichment of 234U in the sample were determined. A method of determining the 235U enrichment in the product stream of the enrichment process used to produce the depleted uranium source was developed. This method makes use of the 234U and 235U waste stream enrichments, as indicated by the depleted uranium source, and a mass balance equation to determine the product 235U enrichment. Since the 235U spectrum was obscured in the electrodeposited source by peak broadening of 238U and 234U, a table of common 235U waste enrichment values was used to compute 235U product enrichments, thereby resulting in a plausible identification of the enrichment process as a Department of Energy HEU enrichment process.

The likelihood of an attack by a terrorist organization using a radiological dispersal device (RDD) is much higher than that of an attack with an improvised nuclear device or true nuclear weapon, as much less technical expertise is required to build an RDD. Consequently, there has been an effort to develop methods for age-dating radiological sealed sources in recent years. One such procedure, described by Steeb et al., is used for determining the age of 90Sr sources. That procedure utilized a rather expensive extraction chromatography resin and was based on an uncommon apparatus with limited sample capacity for the separation step. The procedure also left the Zr fraction contaminated with the radioactive 90Y daughter nuclide. The present work investigates using an alternative separation scheme that utilizes a less costly resin in a widely available column configuration and results in the isolation of 90Sr’s stable granddaughter, 90Zr, without 90Y contamination. This allows the zirconium quantification to be done with a mass spectrometer outside the radiological environment and increases the number of instruments capable of making the measurement, which could allow measurements to be made more quickly.

This paper presents the experimental results of physicochemical properties studies of mixtures based on mineral oil carried out in the laboratory, under thermal stress at fixed temperature with different intervals for long period. The stability study of thermal aging is an essential tool to estimate the lifetime of insulating oil and therefore for the transformer. The tests results allow to make a comparison between the different mixtures proposed and to select the best. It is shown that the degradation rate of oils represented by kinematic viscosity is changed according to ester rate under thermal stress. We can consider that mixtures are less affected than mineral oil, depending on the ester content in the mixture. Results show the strong correlation between viscosity and dissolved decay product, under thermal stress. The increase in the soluble products in the oils, generated by degradation of oil, affects the physical parameter by increasing the kinematic viscosity. These measures are the main criterion to evaluate the stability of physical parameter of oil in-service.

Cryoconites (“cold dust”, derived from the Greek) are aeolian sediments accumulated on glacier surfaces. In cryoconites from the surface of the Stubacher Sonnblickkees, a temperate Austrian glacier, extremely high activity concentrations of artificial and natural radionuclides were found. Artificial radionuclides stem from two clearly distinguishable sources, global fallout from the nuclear weapons testing era deposited over a period of years until roughly 1966 and the fallout from Chernobyl in 1986, which was essentially deposited as a single input during one week. Anthropogenic radionuclides identified were 137Cs, 134Cs, 238Pu, 239+240Pu, 90Sr, 241Am, 60Co, 125Sb, 154Eu, and 207Bi. The naturally occurring radionuclides detected were the long-lived radon decay product 210Pb, the primordial radionuclide 4 K and the cosmogenic 7Be. Isotopic ratios of 134Cs/137Cs and 239+240Pu/238Pu were used to separate the nuclide inventory into the contributions of the two aforementioned sources, which show varying degrees of mixing and provide information on the mixing age of the cryoconites. Since isotopic ratios of Pu often have high uncertainties due to low absolute concentrations, age estimation based on this method can be quite inaccurate. Additional information about the age of cryoconites was obtained through analysis of 210Pb, which is constantly deposited over time.

Guidelines for occupational exposure to radiation are based on annual absorbed or effective dose. Guidelines for Rn exposure are currently based on air concentrations of Rn or decay products. Models of bronchial dose from decay product exposure are based on calculations that have five major parameters with parameter variabilities ranging from 20 to 50%. Many countries currently use the ICRP dose conversion convention, which is a ratio of lifetime Rn lung cancer risk to lifetime atomic bomb dose risk. The results of ongoing epidemiology changed both lifetime risk values, and the dose conversion convention has increased by a factor of 2. Therefore, the current dose conversion convention risk ratio is to be replaced by biokinetic dosimetric models. The main effect of variability in the value of Rn dose factors on industry is that the workplace atmosphere must be characterized accurately, and at present, this is not possible. A history of the dose factor models is central to factor development. The values of the dose model parameters are described illustrating the difficulty in calculation of a dose factor with universal applicability. The objective is to show the range of each parameter and the effect of the dose factor used when reporting occupational or residential bronchial dose.

We present a half-life formalism for describing the disruption of gravitationally-bound few-body systems, with a focus on binary-binary scattering. For negative total encounter energies, the four-body problem has three possible decay products in the point particle limit. For each decay product and a given set of initial conditions, we obtain directly from numerical scattering simulations the half-life for the distribution of disruption times. As in radioactive decay, the half-lives should provide a direct prediction for the relative fractions of each decay product. We test this prediction with simulated data and find good agreement with our hypothesis. We briefly discuss applications of this feature of the gravitational four-body problem to populations of black holes in globular clusters. This paper, the second in the series, builds on extending the remarkable similarity between gravitational chaos at the macroscopic scale and radioactive decay at the microscopic scale to larger-N systems., 17 pages, 18 figures, 2 tables; accepted for publication in MNRAS

A selection of 35 food samples from Japan (plus one seawater sample and one mushroom sample from Russia) were analyzed by gamma spectrometry and liquid scintillation counting. The analytical protocol included concentration of the sample by lyophilization and/or thermal treatment, resulting in exceptionally low limits of detections (in the low mBq/kg range or even below) for the radionuclides 134Cs, 137Cs, 108mAg, and 110mAg, as well as low limits of detection for 90Sr (in the low Bq/kg range). Radiosilver was found in several mussels at low concentrations. Most samples exhibited detectable radiocesium concentrations (below the regulatory limit). An analytical protocol for 90Sr in food was developed and optimized, allowing detection limits in the sub-Bq/kg range. However, despite this high sensitivity, no Japanese food sample exceeded the limit of detection. Only one mushroom sample from Russia revealed detectable traces of 90Sr, but the lack of 134Cs in this sample proves that these radioactive traces did not originate from the Fukushima Daiichi accident. Several moderately time-consuming steps in the analysis of 90Sr increase the sensitivity so far that this radionuclide can be measured directly with high sensitivity, without having to wait for about 2 weeks for the ingrowth of its daughter nuclide 90Y. Our study supports previous studies, which also attested Japanese foods a high level of radiological safety.

In this study, several natural radionuclides (40K, 238U, 235U, 228Ac) and their decay product were investigated in various invertebrate and vertebrate fossils. In the high radioactivity group of fossils, 238U and 235U concentrations increased from 141 to 3621 Bq/kg and from 5.4 to 167 Bq/kg, respectively. In the low radioactivity group of fossils, concentrations of both U isotopes increased from 4.6 to 51 Bq/kg and from 0.18 to 2.3 Bq/kg, respectively. High radioactivity has been linked to the phosphatization process that affected the uranium sorption. Scanning of electron microscope images and X-ray fluorescence analysis were used to confirm the mode of preservation of studied fossils and the presence of a correlation between the phosphorus content and uranium elements in fossil specimens.

The factors causing the distortion of the 128I s− spectrum detected by a self-activated CsI(Tl) scintillator were studied to verify the correctness of the spectral shape and the appropriateness of the discrimination setting for s−-particle counting by the scintillator. These criteria are essential for the correct evaluation of radioactivity generated in a scintillator volume by the self-activation method, which was recently proposed by our group. A pulse height defect caused by the partial escape of s− particles from the surface of the scintillator crystal shifts the s− spectrum toward the lower-energy region when smaller CsI(Tl) scintillators are used (the s−-escape effect). For larger CsI(Tl) scintillators, an increase in pulse height caused by the summing of 0.443 MeV prompt γ -rays from the excited state of the 128I daughter nuclide (128Xe) affects the shape of the s− spectrum considerably, resulting in a shift toward the higher-energy region (the γ -summing effect). The extent of the contributions of these two effects was examined by a Monte Carlo simulation of various cubical CsI(Tl) crystals of different sizes. It was found that the distortions caused by those two effects effectively cancel each other out for a medium-size cubical CsI(Tl) crystal with a side length of approximately 3 cm. This finding is very useful for the practical applications of the self-activation method. In addition to the factors mentioned above, the efficiency of scintillation light collection by the photodetectors also affects the shape distortion of the s− spectrum slightly through spectral line broadening due to the degradation of the energy resolution. This effect was estimated using a simple model with different discrimination settings for s− pulse counting.

Merging neutron stars produce "kilonovae"---electromagnetic transients powered by the decay of unstable nuclei synthesized via rapid neutron capture (the r-process) in material that is gravitationally unbound during inspiral and coalescence. Kilonova emission, if accurately interpreted, can be used to characterize the masses and compositions of merger-driven outflows, helping to resolve a long-standing debate about the origins of r-process material in the Universe. We explore how the uncertain properties of nuclei involved in the r-process complicate the inference of outflow properties from kilonova observations. Using r-process simulations, we show how nuclear physics uncertainties impact predictions of radioactive heating and element synthesis. For a set of models that span a large range in both predicted heating and final abundances, we carry out detailed numerical calculations of decay product thermalization and radiation transport in a kilonova ejecta with a fixed mass and density profile. The light curves associated with our models exhibit great diversity in their luminosities, with peak brightness varying by more than an order of magnitude. We also find variability in the shape of the kilonova light curves and their color, which in some cases runs counter to the expectation that increasing levels of lanthanide and/or actinide enrichment will be correlated with longer, dimmer, redder emission., Submitted to ApJ; comments welcome

Long-term measurements of the 222Rn concentration, 222Rn decay product activity, particle size distribution, and unattached, and attached 222Rn decay products, were made at two locations using the 22 y radon decay product 210Pb as their tracer. The particle size sampler collects both short lived 222Rn decay products that ultimately decay to 210Pb on the filters, and also airborne 210Pb. The measurements were made outdoors, at a suburban home and at Fernald, OH, a former uranium processing facility, on top of one of the two 226Ra storage silos containing 150 TBq 226Ra. The size distributions showed the unattached fractions, i.e. particle diameter 2-4 nm, to be 1.5% at the home and 14% at the silos. The unattached fraction of 218Po can be shown to be an immediate measure of the 222Rn concentration. The data indicates detection of the pressure driven 222Rn flow at the silo and with the enhanced measurement capability of a filtered air source versus the usual 222Rn gas measurement. It is proposed that real time measurements of unattached 218Po may be used to identify rapidly changing 222Rn concentrations associated with pressure driven soil air flow associated with seismic activity.

Variations in the 238 U/ 235 U ratio are mostly observed in association with changes in the uranium oxidation state and therefore controlled by changes in the redox conditions, although evidence for this process has so far been indirect. Here, the δ 238 U and δ 234 U isotope composition of different redox species is studied for the first time within the same geological samples: the bulk, reduced (U(IV)) and oxidized (U(VI)) uranium species in seafloor phosphorites. In all cases, δ 238 U(IV) is higher (− 0.27 to − 0.81) than corresponding δ 238 U(VI) (− 0.64 to − 1.07), with δ 234 U(VI) displaying extremely high values (~ 500–2000) relative to δ 234 U(IV) (− 240 to − 100). By comparison, the bulk δ 238 U, δ 234 U and U concentrations are − 0.42 to − 0.85, − 10 to + 20, and 63–328 ppm, respectively. These values are mostly in the range of natural variations in previously reported samples, with the bulk δ 238 U and δ 234 U values corresponding with seawater values except for a tail in δ 238 U toward lower values. The main exception is displayed by the composition of the U(VI) fraction, which ranges toward relatively low δ 238 U values but has a very strong positive δ 234 U excursion relative to comparable samples elsewhere. Given that the studied phosphorites formed in high productivity environments, where oxygen consumption was high and hence anoxic conditions could have been favored, it is assumed that most of the initial uranium in the samples was in reduced form. Indeed, even if some of the U oxidized over time, the studied samples still consist of approximately 60–80% U(IV). The process of 238 U radioactive decay resulted in the oxidation of the decay product, 234 U, and consequently, the δ 234 U(VI) within the samples has very high values. The evolution of δ 238 U is related to the effect of the ‘nuclear field shift’, which predicts that nuclides with higher atomic masses will be reduced preferentially over those with lower atomic masses. Accordingly, it is easier to reduce 238 U than 235 U in the same environment, which would result in higher δ 238 U of U(IV). This is indeed the case observed here, although in addition, the evidence here shows that the δ 238 U fractionation occurred during U oxidation and that the final differences of δ 238 U between both oxidation states reflect the combined effect of the depositional nuclear field shift and the in-situ recoil-related oxidation . A set of quantitative models are used to evaluate the role and rate of the different processes and suggest that because of the independent evolution of U(IV) and U(VI) over time, their relative fraction and isotopic compositions can be used to evaluate the formation ages of seafloor phosphorites, which has so far not been possible using U-decay series.