ДИНАМИКА ИЗМЕНЕНИЙ РАЦИОНОВ ПИТАНИЯ НАСЕЛЕНИЯ БРЯНСКОЙ ОБЛАСТИ, ЖИВУЩЕГО НА ТЕРРИТОРИЯХ, ЗАГРЯЗНЕННЫХ В РЕЗУЛЬТАТЕ АВАРИИ НА ЧЕРНОБЫЛЬСКОЙ АЭС

During the years passed after the Chernobyl accident we are carrying out monitoring of the radiation situation in the Sough-Western territories of the Bryansk region, contaminated with the long-living radionuclides which includes 137Сs concentration measurements in agricultural and natural foodstuffs, surveys of local populations on the structure and composition of the diet accompanied with 137Сs content measurements in the human body. In the article the obtained data is systematized on the food rations of the adult population of theBryansk region, on food rations dynamics in the first and following years after the accident, which is necessary for the correct estimation of internal exposure doses of the population living on the contaminated territories.На протяжении всех прошедших после аварии на Чернобыльской АЭС лет нами осуществлялся  мониторинг  радиационной  обстановки  в  юго-западных  районах  Брянской  области,  загрязненных долгоживущими радионуклидами, включающий в себя определение концентраций 137Сs в пищевых продуктах как сельскохозяйственного производства, так и природного происхождения, опрос местного населения о структуре и составе их рационов питания с одновременным измерением содержания 137Сs в организме жителей.В данной работе систематизированы полученные нами данные о рационах питания взрослых жите-лей Брянской области, об их изменениях в первые и последующие годы после аварии, что необходимо для корректной оценки доз внутреннего облучения жителей, проживающих на загрязненных территориях

ЭФФЕКТИВНОСТЬ ЗАЩИТНЫХ МЕРОПРИЯТИЙ ПО СНИЖЕНИЮ ДОЗЫ ВНУТРЕННЕГО ОБЛУЧЕНИЯ РАДИОНУКЛИДАМИ ЦЕЗИЯ ЖИТЕЛЕЙ ЗОНЫ РАДИОАКТИВНОГО ЗАГРЯЗНЕНИЯ В ПЕРВЫЕ ГОДЫ ПОСЛЕ АВАРИИ НА ЧАЭС

In the paper, we use the data on the content of caesium radionuclides in foodstuffs and in Bryansk region adult inhabitant’s body, on their food ration and its changes during the first years after the Chernobyl accident, and on the measures to protect the population from internal exposure. We calculate dynamics of 137Cs intake in the body and its contents therein, while maintaining a traditional diet and while replacing food products for radiationfree ones. The results show that the actual 137Cs content in the body is usually below the one calculated on the basis of the food ration. It was found out that individual 137Cs contents in the body correlate with the rate of meat, dairy and natural food products consumption and with factors of protection from internal exposure. The efficiency of the protective measures to reduce the intake and the content of caesium radionuclides in the body of inhabitants, as well as the average effective dose in the first years after the accident has been quantitatively assessed.В работе получены и использованы данные о содержании радионуклидов цезия в пищевых продуктах и организме взрослых жителей Брянской области, об их рационе питания и его изменениях в первые годы после аварии на ЧАЭС, о мерах защиты населения от внутреннего облучения. Рассчитана динамика поступления 137Cs в организм и содержания в нем при сохранении традиционной диеты и при замене продуктов на радиационно чистые. Показано, что фактическое содержание 137Cs в организме, как правило, ниже рассчитанного по рациону. Выявлено, что индивидуальное содержание 137Cs в организме коррелирует с размерами потребления мясо-молочных и природных продуктов и с факторами защиты от внутреннего облучения. Количественно оценена эффективность комплекса защитных мер в уменьшении поступления и содержания радионуклидов цезия в организме жителей, а также средней эффективной дозы в первые годы после аварии

Ultrafast nuclear dynamics in the doubly-core-ionized water molecule observed via Auger spectroscopy

We present a combined experimental and theoretical study of the Auger-emission spectrum following double core ionization and excitation of gas-phase water molecules with hard-x-ray synchrotron radiation above the O K−2 threshold. We observe an indication of ultrafast proton motion occurring within the 1.5 fs lifetime of the double-core-hole (DCH) states in water. Furthermore, we have identified symmetric and antisymmetric dissociation modes characteristic for particular DCH states. Our results serve as a fundamental reference for state-of-the-art studies of DCH dynamic processes in liquid water both at synchrotron and free-electron-laser facilities

Subfemtosecond Control of Molecular Fragmentation by Hard X-Ray Photons

Tuning hard x-ray excitation energy along Cl 1s→σ∗ resonance in gaseous HCl allows manipulating molecular fragmentation in the course of the induced multistep ultrafast dissociation. The observations are supported by theoretical modeling, which shows a strong interplay between the topology of the potential energy curves, involved in the Auger cascades, and the so-called core-hole clock, which determines the time spent by the system in the very first step. The asymmetric profile of the fragmentation ratios reflects different dynamics of nuclear wave packets dependent on the photon energy

Single and multiple excitations in double-core-hole states of free water molecules

We present a combined experimental and theoretical study of the double-core-hole photoelectron spectrum obtained in isolated water molecules irradiated with hard x-rays above the oxygen K−2 threshold. States of the type O K−2V and multiply excited states are created by single-photon absorption and subsequent one-electron emission. A detailed analysis enabled by high experimental resolution reveals dissociative nuclear dynamics in the K−2V pre-edge states. At the binding energies above the K−2 double-ionization potential, a complex spectral pattern is observed and attributed to highly excited states involving multiple shake-up excitation processes with the aid of state-of-the-art theoretical calculations. A strong broadening due to the nuclear motion indicates a highly dissociative nature of these multiply excited states, in agreement with the theoretical analysis

Argon as a showcase

Electronic-state–lifetime interference is a phenomenon specific for ionization of atoms and molecules in the hard-x-ray regime. Using resonant KL2,3L2,3 Auger decay in argon as a showcase, we present a model that allows extracting the interference terms directly from the cross sections of the final electronic states. The analysis provides fundamental information on the excitation and decay processes such as probabilities of various decay paths and the values of the dipole matrix elements for transitions to the excited states. Our results shed light on the interplay between spectator, shake-down, and shake-up processes in the relaxation of deep core-hole states

Energy Transfer into Molecular Vibrations and Rotations by Recoil in Inner-Shell Photoemission

A mixture of CF4 and CO gases is used to study photoelectron recoil effects extending into the tender x-ray region. In CF4, the vibrational envelope of the C 1s photoelectron spectrum becomes fully dominated by the recoil-induced excitations, revealing vibrational modes hidden from Franck-Condon excitations. In CO, using CF4 as an accurate energy calibrant, we determine the partitioning of the recoil-induced internal excitation energy between rotational and vibrational excitation. The observed rotational recoil energy is 2.88(28) times larger than the observed vibrational recoil energy, well in excess of the ratio of 2 predicted by the basic recoil model. The experiment is, however, in good agreement with the value of 2.68 if energy transfer via Coriolis coupling is included

Detailed assignment of normal and resonant Auger spectra of Xe near the L edges

We present a comprehensive experimental and theoretical investigation on the LMM, LMN, and LNN normal Auger spectra of xenon, which reveal excellent agreement with theory when core-hole lifetimes of the two-hole final states are taken into account. Generally, the spectra turned out to be highly complex due to a strong overlap of the Auger transitions subsequent to 2s−11/2, 2p−11/2, and 2p−13/2 ionization. This overlap is due to the splitting of the three initial L core holes and the different final M and N core holes being on the same order of magnitude of several hundred eV. The Auger transitions are assigned in detail based on the theoretical results. Most of the MM, MN, and NN final states are described well based on jj coupling. In addition, we present a detailed assignment of the resonant LM45M45 Auger transition subsequent to the 2s→6p, 7p and 2p→5d, 6d excitations

Potential Energy Surface Reconstruction and Lifetime Determination of Molecular Double-Core-Hole States in the Hard X-Ray Regime

A combination of resonant inelastic x-ray scattering and resonant Auger spectroscopy provides complementary information on the dynamic response of resonantly excited molecules. This is exemplified for CH3I, for which we reconstruct the potential energy surface of the dissociative I 3d−2 double- core-hole state and determine its lifetime. The proposed method holds a strong potential for monitoring the hard x-ray induced electron and nuclear dynamic response of core-excited molecules containing heavy elements, where ab initio calculations of potential energy surfaces and lifetimes remain challenging

ПУТИ ФОРМИРОВАНИЯ ДОЗ ВНУТРЕННЕГО ОБЛУЧЕНИЯ СЕЛЬСКИХ ЖИТЕЛЕЙ БРЯНСКОЙ ОБЛАСТИ ПОСЛЕ АВАРИИ НА ЧАЭС (Часть первая)

In a large village Veprin of the Bryanskregion of Russiacontaminated with radionuclides as a result of the Chernobylaccident, 137Сs concentration in food products of agricultural produce and natural origin was regularly measured, local inhabitants were polled on the composition of their food ration, and 137Сs content in their bodies was at the same time measured. These results were used as the basis for calculation of annual effective doses of internal exposure to inhabitants and for reconstruction of the dose during the entire period after the accident. It will be divided into two stages: 1986–1996 yy and 1997–2012 yy. In this paper devoted to the first period (1986–1996), internal dose was reconstructed for 11 years after the accident, and the efficiency of countermeasures performed for reduction of the internal dose was assessed. The internal dose to inhabitants during the past 11 years after the accident was shown to be reduced almost twice, namely down to 35 mSv instead of the expected 70 mSv. The dose of external gamma radiation during the same time period is close to the obtained dose of internal exposure. The presence of peat and water-meadow soils in the vicinity of this village that are characterised by high transfer factors for radionuclides from soil to vegetation causes high contribution of internal exposure in the total dose of population exposure. Contribution of natural products to the internal dose grew from 6% in 1987 up to 25% in 1996. Individual content of 137Сs in the body of inhabitants reliably correlates with the consumption of milk in the early period after the accident and with consumption of forest mushrooms in the remote period.На протяжении всех прошедших после аварии на Чернобыльской АЭС лет нами осуществлялся мониторинг радиационной обстановки населенном пункте Веприн Брянской области России, включающий в себя определение концентраций 137Сs в пищевых продуктах как сельскохозяйственного производства, так и природного происхождения, опрос местного населения о структуре и составе их рационов питания с одновременным измерением содержания 137Сs в организме жителей. Анализ результатов этих многолетних исследований будет разделен на два этапа: 1986–1996 гг. и 1997– 2012 гг. В данной работе, посвященной первому периоду исследований (1986–1996), была реконструирована доза внутреннего облучения населения за 11 лет, прошедших после аварии, а также проведена оценка эффективности комплекса защитных мероприятий, проведенных в данном населенном пункте в указанное время. Показано, что благодаря последним среднюю годовую дозу внутреннего облучения жителей за рассматриваемый период удалось снизить почти в два раза, а именно до 35 мЗв/ год вместо ожидаемых 70 мЗв/год. Доза внешнего облучения в течение того же периода времени была близка к полученной дозе внутреннего облучения. Наличие в ареале этого населенного пункта значительных площадей с торфяными и пойменными почвами, характеризующимися высокими коэффициентами перехода радионуклидов из почвы в растительность, привело к более существенному радиоактивному загрязнению выращиваемой сельскохозяйственной продукции, чем в большинстве других хозяйств Брянского региона, что, в свою очередь, определило более высокий вклад этой компоненты в дозу внутреннего облучения населения. Индивидуальное содержание 137Сs в организме жителей достоверно коррелирует с потреблением молока в ранний период после аварии и потреблении ем лесных грибов в отдаленный период. Вклад даров природы в дозу внутреннего облучения вырос с 6% в 1987 г. до 25% в 1996 г