Parity nonconservation effect in the resonance elastic electron scattering on heavy He-like ions

We investigate the parity nonconservation effect in the elastic scattering of polarized electrons on heavy He-like ions, being initially in the ground state. The enhancement of the parity violation is achieved by tuning the energy of the incident electron in resonance with quasidegenerate doubly-excited states of the corresponding Li-like ion. We consider two possible scenarios. In the first one we assume that the polarization of the scattered electron is measured, while in the second one it is not detected.Comment: 13 pages, 3 figures, 2 table

Parity nonconservation effect in the dielectronic recombination of polarized electrons with heavy He-like ions

We investigate the parity nonconservation (PNC) effect in the dielectronic recombination (DR) of a polarized electron with a heavy He-like ion into doubly-excited $((1s 2p_{1/2})_{0} n{\kappa})_{1/2}$ and $\left(\left(1s 2s\right)_{0} n{\kappa}\right)_{1/2}$ states of Li-like ion. We determine the nuclear charge number $Z$ for which these opposite-parity levels are near to cross and, therefore, the PNC effect will be significantly enhanced. Calculations are performed for quantum numbers $n \geq 4$ and $\kappa = \pm 1$.Comment: 12 pages, 1 figur

Parity violation in the resonance elastic electron scattering on He-like uranium

Synopsis Parity violation on the cross section of the resonance elastic electron scattering by He-like uranium ion is studied. It is assumed that the incident electron is polarized and tuned in resonance with one of the close-lying opposite-parity states

Backward scattering of low-energy antiprotons by highly charged and neutral uranium: Coulomb glory

Collisions of antiprotons with He-, Ne-, Ni-like, bare, and neutral uranium are studied theoretically for scattering angles close to 180$^{\circ}$ and antiproton energies with the interval 100 eV -- 10 keV. We investigate the Coulomb glory effect which is caused by a screening of the Coulomb potential of the nucleus and results in a prominent maximum of the differential cross section in the backward direction at some energies of the incident particle. We found that for larger numbers of electrons in the ion the effect becomes more pronounced and shifts to higher energies of the antiproton. On the other hand, a maximum of the differential cross section in the backward direction can also be found in the scattering of antiprotons on a bare uranium nucleus. The latter case can be regarded as a manifestation of the screening property of the vacuum-polarization potential in non-relativistic collisions of heavy particles.Comment: 14 pages, 5 figure

ИЗУЧЕНИЕ ПРОЦЕССА СООСАЖДЕНИЯ МЫШЬЯКА И СУРЬМЫ ПРИ ОТДЕЛЕНИИ МАКРОКОЛИЧЕСТВ ЖЕЛЕЗА, ХРОМА В ВИДЕ Na3FeF6, Na3CrF6

Theoretical and experimental studies were carried out for the first time in order to determine the mechanism of co-precipitation of arsenic and antimony during their separation from the macro-quantities of iron and chromium in the form of Na3FeF6 and Na3CrF6 sediments. It was found that the application of Dubinin-Radushkevich adsorption isotherm gives the most accurate description of the process. The average free energy of adsorption for As and Sb is 9.6 and 9.7 kJ/mol respectively. Co-precipitation of analytes in the micropores of precipitates occurred as a result of the chemical (ion-exchange) reaction. The possibility of inhibiting this process by introducing a different amount of complexing agent (hydrofluoric acid) was studied. The addition of HF led to the formation of more coarse crystalline precipitates with lower specific surface area and porosity. For the accurate ICP-AES determination of analytes (As, Sb) the molar ratio of precipitating agent / complexing agent (NaF / HF) ≈ 1 should be strictly observed. According to the developed procedure, state standard samples of steels and nickel-based precision alloys were prepared for ICP-AES determination of As and Sb contents. The difference between the found and certified content of analytes did not exceed the permitted deviations given in the corresponding Russian state standards. The ICP-AES method of simultaneous determination of As and Sb contents after their preliminary separation from the main components is recommended for the analysis of materials with high content of Fe and Cr.Keywords: sorption, co-precipitation, determination of arsenic and antimony, inductively coupled plasma atomic emission spectroscopy (ICP-AES), adsorption isotherms, fluorides, matrix componentsDOI: http://dx.doi.org/10.15826/analitika.2017.21.3.001 A.V. Maiorova1, S.Yu. Melchakov1,2, T.G. Okuneva2 , K.A. Vorontsova1, M.A. Mashkovtsev21Institute of Metallurgy of Ural Branch of Russian Academy of Sciences,101 Amundsena st., Yekaterinburg, 620016, Russian Federation2Ural Federal University, 19 Mira st., Yekaterinburg, 620002, Russian FederationВпервые проведены теоретические и экспериментальные исследования с целью определения механизма соосаждения мышьяка и сурьмы при отделении от макроколичеств железа, хрома в виде Na3FeF6, Na3CrF6. Установлено, что использование изотермы адсорбции Дубинина-Радушкевича приводит к наиболее точному описанию процесса. Средняя свободная энергия адсорбции для As и Sb принимает значения 9.6 и 9.7 кДж/моль соответственно. Соосаждение в микропорах осадков происходит в результате химической (ионообменной) реакции. Изучена возможность ингибирования процесса с помощью введения разного количества комплексообразующего агента – фтороводородной кислоты. Ее использование приводит к получению более крупнокристаллических осадков с меньшей удельной поверхностью и пористостью. Для точного ИСП-АЭС определения аналитов необходимо строгое соблюдение мольного соотношения осадитель/комплексообразующий агент (NaF/HF) ≈ 1. По разработанной процедуре к ИСП-АЭС определению содержания As и Sb были подготовлены ГСО состава стали и сплавов прецизионного типа на никелевой основе. Разница между найденным и аттестованным их содержанием не превышает нормативов, приведенных в соответствующих ГОСТах.  ИСП-АЭС методика одновременного определения содержания As и Sb с предварительным отделением основных компонентов рекомендована для анализа материалов с высоким содержанием Fe и Cr.Ключевые слова: адсорбция, соосаждение, определение мышьяка и сурьмы, атомно-эмиссионная спектрометрия с индуктивно связанной плазмой (ИСП-АЭС), изотермы адсорбции, фториды, матричные компонентыDOI: http://dx.doi.org/10.15826/analitika.2017.21.3.00