Study of refractive structure in the inelastic 16O+16O scattering at the incident energies of 250 to 1120 MeV

The data of inelastic 16O+16O scattering to the lowest 2+ and 3- excited states of 16O have been measured at Elab = 250, 350, 480, 704 and 1120 MeV and analyzed consistently in the distorted wave Born approximation (DWBA), using the semi- microscopic optical potentials and inelastic form factors given by the folding model, to reveal possible refractive structure of the nuclear rainbow that was identified earlier in the elastic 16O+16O scattering channel at the same energies. Given the known transition strengths of the 2+ and 3- states of 16O well determined from the (e,e') data, the DWBA description of the inelastic data over the whole angular range was possible only if the absorption in the exit channels is significantly increased (especially, for the 16O+16O(2+) exit channel). Although the refractive pattern of the inelastic 16O+16O scattering was found to be less pronounced compared to that observed in the elastic scattering channel, a clear remnant of the main rainbow maximum could still be seen in the inelastic cross section at Elab = 350 - 704 MeV.Comment: 26 pages, 10 figures, Accepted for publication in Nucl. Phys.

ОЦЕНКА АНАЛИТИЧЕСКИХ ВОЗМОЖНОСТЕЙ РЕНТГЕНОФЛУОРЕСЦЕНТНОЙ СПЕКТРОМЕТРИИ С ПОЛНЫМ ВНЕШНИМ ОТРАЖЕНИЕМ ПРИ АНАЛИЗЕ НАПИТКОВ С МАТРИЦЕЙ САХАРОЗЫ

Multielement analysis of food products, including drinks, is important for an assessment of the content of the useful and toxic elements for the human body. In this paper, the main problems and their solutions in the analysis of sugar-containing drinks by Total Reflection X-ray Fluorescence Spectrometry (TXRF) method have been considered. The organic sucrose matrix causes certain difficulties both in the preparation of the samples and in the processing of measurement data for TXRF. The following most common sample preparation procedures for TXRF were considered: direct, based on the analysis of initial sample, dilution with water and acid digestion. In order to assess the fulfillment of the thin layer criterion, the physical characteristics of dried samples on the carriers were determined after applying each of the above-mentioned preparation procedures, and the corresponding surface density values were established. The obtained values were compared with the theoretical ones. Based on the calculation of mass absorption coefficients for C12H22O11 matrix, it was found that the method of acid digestion was suitable for the quantitative determination of light (14 Z 20) elements. When analyzing the sample without the preliminary preparation or after diluting the sample with water, the influence of absorption effects was noted due to the mismatch of the surface density with the thin layer criterion. This mismatch of the samples in the direct analysis was confirmed by the measurements using a method based on an angle incidence scanning of the primary radiation on the sample, establishing a violation of the conditions for the effect of total external reflection. The detection limits were calculated for the considered sample preparation procedures, and it was concluded that the quantitative identification of Fe, Ni, Cu, Zn, Rb, Sr, and Pb trace elements at the level of tens of μg/l was possible by the acid digestion procedure. The application of the addition method to assess the trueness of elemental determination led to the conclusion that it was possible to use the direct analysis of sugar-containing drinks for the elements with Z ≥ 24 in the concentration ranges of 0.5–10 mg/l.Key words: X-ray fluorescence, TXRF, soft drinks, matrix effects, absorption effects, sucrose, multielement analysis, addition method(Russian)DOI: http://dx.doi.org/10.15826/analitika.2019.23.4.009A.S. Maltsev1, 2, A. von Bohlen3, R.A. Yusupov2, S.A. Bakhteev2 1 Institute of the Earth’s Crust, SB RAS, Lermontov st., 128, Irkutsk, 664033, Russian Federation2 Kazan National Research Technological University, Marksa st., 68, Kazan, 420012, Russian Federation3 Leibniz-Institut für Analytische Wissenschften ISAS, Bunsen-Kirchhoff-Str. 11, Dortmund, 44139, GermanyМногоэлементный анализ пищевой продукции, в т.ч. напитков, важен при оценке содержания полезных и токсичных для организма элементов. В данной работе рассмотрены основные проблемы и их решения при анализе сахаросодержащих напитков методом рентгенофлуоресцентной спектрометрии с полным внешним отражением (TXRF). Органическая матрица сахарозы вызывает определенные сложности как при подготовке проб, так и при обработке данных измерений для TXRF. Рассмотрены наиболее распространенные для TXRF способы подготовки проб: прямой, заключающийся в анализе исходного образца, разбавление водой и кислотное разложение. Для оценки выполнения критерия тонкого слоя определены физические характеристики высушенных проб на подложках после применения каждого из способов подготовки и установлены значения поверхностной плотности. Полученные значения сравнили с теоретическими, исходя из расчета массовых коэффициентов поглощениядля матрицы C12H22O11, и установили, что для количественного определения легких (14 Z 20) элементов подходит способ кислотного разложения. При анализе образца без предварительной подготовки или после разбавления образца водой отмечено влияние эффектов поглощения, обусловленные несоответствием поверхностной плотности критерию тонкого слоя. Это несоответствие проб при прямом анализе подтвердили с помощью измерений с использованием способа, основанного на сканировании угла падения первичного излучения на образец, установив нарушение условий эффекта полного внешнего отражения. Для рассмотренных вариантов пробоподготовки рассчитаны пределы обнаружения, и сделан вывод о том, что при кислотном разложении возможна количественная идентификация микроэлементов Fe, Ni, Cu, Zn, Rb, Sr, Pb на уровне десятков мкг/л. Применение способа добавок, используемого для контроля правильности определения элементов, позволило заключить о возможности использования прямого способа анализа сахаросодержащих напитков для элементов c Z ≥ 24 в диапазонах концентраций 0.5-10 мг/л.Ключевые слова: рентгенофлуоресцентный анализ, РФА ПВО, напитки, матричные эффекты, эффекты поглощения, сахароза, многоэлементный анализ, способ добавокDOI: http://dx.doi.org/10.15826/analitika.2019.23.4.00

From the stable to the exotic: clustering in light nuclei

A great deal of research work has been undertaken in alpha-clustering study since the pioneering discovery of 12C+12C molecular resonances half a century ago. Our knowledge on physics of nuclear molecules has increased considerably and nuclear clustering remains one of the most fruitful domains of nuclear physics, facing some of the greatest challenges and opportunities in the years ahead. The occurrence of "exotic" shapes in light N=Z alpha-like nuclei is investigated. Various approaches of the superdeformed and hyperdeformed bands associated with quasimolecular resonant structures are presented. Evolution of clustering from stability to the drip-lines is examined: clustering aspects are, in particular, discussed for light exotic nuclei with large neutron excess such as neutron-rich Oxygen isotopes with their complete spectroscopy.Comment: 15 pages, 5 figures, Presented at the International Symposium on "New Horizons in Fundamental Physics - From Neutrons Nuclei via Superheavy Elements and Supercritical Fields to Neutron Stars and Cosmic Rays" held at Makutsi Safari Farm, South Africa, December 23-29, 2015. arXiv admin note: substantial text overlap with arXiv:1402.6590, arXiv:1303.0960, arXiv:1408.0684, arXiv:1011.342

Real-time dynamics of the formation of hydrated electrons upon irradiation of water clusters with extreme ultraviolet light

Free electrons in a polar liquid can form a bound state via interaction with the molecular environment. This so-called hydrated electron state in water is of fundamental importance e.g.~in cellular biology or radiation chemistry. Hydrated electrons are highly reactive radicals that can either directly interact with DNA or enzymes, or form highly excited hydrogen (H∗) after being captured by protons. Here, we investigate the formation of the hydrated electron in real-time employing XUV femtosecond pulses from a free electron laser, in this way observing the initial steps of the hydration process. Using time-resolved photoelectron spectroscopy we find formation timescales in the low picosecond range and resolve the prominent dynamics of forming excited hydrogen states

Structure of excited states of Be-11 studied with Antisymmetrized Molecular Dynamics

The structures of the ground and excited states of Be-11 were studied with a microscopic method of antisymmetrized molecular dynamics. The theoretical results reproduce the abnormal parity of the ground state and predict various kinds of excited states. We suggest a new negative-parity band with a well-developed clustering structure which reaches high-spin states. Focusing on a $2\alpha$ clustering structure, we investigated structure of the ground and excited states. We point out that molecular orbits play important roles for the intruder ground state and the low-lying $2\hbar \omega$ states. The features of the breaking of $\alpha$ clusters were also studied with the help of data for Gamow-Teller transitions.Comment: 24 pages, 7 figures, to be submitted to Phys.Rev.

Clusters in Light Nuclei

A great deal of research work has been undertaken in the alpha-clustering study since the pioneering discovery, half a century ago, of 12C+12C molecular resonances. Our knowledge of the field of the physics of nuclear molecules has increased considerably and nuclear clustering remains one of the most fruitful domains of nuclear physics, facing some of the greatest challenges and opportunities in the years ahead. In this work, the occurence of "exotic" shapes in light N=Z alpha-like nuclei is investigated. Various approaches of superdeformed and hyperdeformed bands associated with quasimolecular resonant structures are presented. Results on clustering aspects are also discussed for light neutron-rich Oxygen isotopes.Comment: 12 pages, 5 figures. Invited Talk presented by C. Beck at the Zakopane Conference on Nuclear Physics "Extremes of the Nuclear Landscape" XLV in the series of Zakopane Schools of Physics - International Symposium - Zakopane, Poland, August 30 - September 5, 2010.To be publihed in Acta Physica Polonica B42 no 3, March 201

Unbound exotic nuclei studied by transfer to the continuum reactions

In this paper we show that the theory of transfer reactions from bound to continuum states is well suited to extract structure information from data obtained by performing "spectroscopy in the continuum". The low energy unbound states of nuclei such as $^{10}$Li and $^{5}$He can be analyzed and the neutron-core interaction, necessary to describe the corresponding borromean nuclei $^{11}$Li and $^{6}$He can be determined in a semi-phenomenological way. An application to the study of $^{10}$Li is then discussed and it is shown that the scattering length for s-states at threshold can be obtained from the ratio of experimental and theoretical cross sections. The scattering single particle states of the system n+$^{9}$Li are obtained in a potential model. The corresponding S-matrix is used to calculate the transfer cross section as a function of the neutron continuum energy with respect to $^{9}$Li. Three different reactions are calculated $^{9}Li(d,p)^{10}Li$, $^{9}Li(^{9}Be,^{8}Be)^{10}Li$, $^{9}Li(^{13}C,^{12}C)^{10}Li$, to check the sensitivity of the results to the target used and in particular to the transfer matching conditions. Thus the sensitivity of the structure information extracted from experimental data on the reaction mechanism is assessed.Comment: 21 pages, 5 ps figures, accepted for publication on Nucl. Phys.

Evolution and ion kinetics of a XUV-induced nanoplasma in ammonia clusters

High-intensity extreme ultraviolet (XUV) pulses from a free-electron laser can be used to create a nanoplasma in clusters. In Ref. [Michiels et al. PCCP, 2020; 22: 7828-7834] we investigated the formation of excited states in an XUV-induced nanoplasma in ammonia clusters. In the present article we expand our previous study with a detailed analysis of the nanoplasma evolution and ion kinetics. We use a time-delayed UV laser as probe to ionize excited states of H and H$_2^+$ in the XUV-induced plasma. Employing covariance mapping techniques, we show that the correlated emission of protons plays an important role in the plasma dynamics. The time-dependent kinetic energy of the ions created by the probe laser is measured, revealing the charge neutralization of the cluster happens on a sub-picosecond timescale. Furthermore, we observe ro-vibrationally excited molecular hydrogen ions H$_2^{+*}$ being ejected from the clusters. We rationalize our data through a qualitative model of a finite-size non-thermal plasma