Low energy (p,γp,\gamma) reactions in Ni and Cu nuclei using microscopic optical model

Radiative capture reactions for low energy protons have been theoretically studied for Ni and Cu isotopes using the microscopic optical model. The optical potential has been obtained in the folding model using different microscopic interactions with the nuclear densities from Relativistic Mean Field calculations. The calculated total cross sections as well as the cross sections for individually low lying levels have been compared with measurements involving stable nuclear targets. Rates for the rapid proton capture process have been evaluated for astrophysically important reactions.Comment: To appear in Physical Review

О связи протонного облучения и термической обработки монокристаллического кремния с его структурой

The method of two-crystal X-ray diffractometry is used to control the quality and perfection of monocrystalline silicon obtained by implantation of hydrogen ions and subsequent thermal annealing, which is used in a number of semiconductor technologies. The principal feature of this approach is the ability to quickly obtain reliable experimental results, which was confirmed in this paper by the use of X-ray topography. The presented data provide information on the state of the disturbed layer of silicon crystals of n-type conductivity (ρ = 100 Om ⋅ cm) by orientation (111), 2 mm thick, implanted by protons with energy E = 200, 300, 100 + 200 + 300 keV, dose D = 2 ⋅ 1016cm-2 and subjected to subsequent thermal treatment in the temperature range T from 100 to 900 °С. We have established a non-monotonic dependence of the integral characteristics of the disturbed layer, namely the average effective thickness Leff and the average relative deformation ∆а/а, on annealing temperature, with the maximum level of distortion in the field of temperature ∼300 °С, using the method of integral characteristics. Obtained data allowed to assess the general condition of disturbed layer during thermal treatment.Метод двухкристальной рентгеновской дифрактометрии применен для контроля качества и совершенства монокристаллического кремния, получаемого с помощью имплантации ионов водорода и последующего термического отжига, который используется в ряде полупроводниковых технологий. Принципиальная особенность данного подхода состоит в возможности быстрого получения надежных экспериментальных результатов, что было подтверждено путем использования рентгеновской топографии. Представлены данные о состоянии нарушенного слоя кристаллов кремния n-типа проводимости (ρ = 100 Ом ⋅ см) ориентацией (111) толщиной 2 мм, имплантированных протонами с энергией Е = 200, 300 и 100 + 200 + 300 кэВ и дозой имплантации D = 2 ⋅ 1016 см-2 и подвергнутых последующей термической обработке в интервале температур Т от 100 до 900 °С. С использованием метода интегральных характеристик установлена немонотонная зависимость интегральных характеристик нарушенного слоя, а именно: средней эффективной толщины Lэфф и средней относительной деформации ∆а/а от температуры отжига, с максимальным уровнем искажений в области температуры ∼300 °С. Показано, что полученные данные позволили оценить общее состояние нарушенного слоя при термообработке

Systematic study of (p,γ) reactions on Ni isotopes

A systematic study of the radiative proton capture reaction for all stable nickel isotopes is presented. The results were obtained using 2.0-6.0 MeV protons from the 11-MV tandem Van de Graaff accelerator at the University of Notre Dame. The γ rays were detected by the NSCL-SuN detector utilizing the γ-summing technique. The results are compared to a compilation of earlier measurements and discrepancies between the previous data are resolved. The experimental results are also compared to the theoretical predictions obtained using the non-smoker and smaragd codes. Based on these comparisons an improved set of astrophysical reaction rates is proposed for the (p,γ) reactions on the stable nickel isotopes as well as for the 56Ni(p,γ)57Cu reaction.Peer reviewedFinal Accepted Versio

Effect of proton doping and heat treatment on the structure of single crystal silicon

The quality and structural perfection of single crystal silicon have been studied using double-crystal X-ray diffraction after hydrogen ion implantation and thermal annealing used in a number of semiconductor technologies. The fundamental difference of this approach is the possibility to rapidly obtain reliable experimental results which were confirmed using X-ray topography. Data have been presented for the condition of the damaged layer in n-type silicon single crystals (r = 100 W × cm) having the (111) orientation and a thickness of 2 mm after proton implantation at energies E = 200, 300 and 100 + 200 + 300 keV and dose D = 2 × 1016 cm-2 and subsequent heat treatment in the T = 100–900 °C range. Using the method of integral characteristics we have revealed a nonmonotonic dependence of the integral characteristics of the damaged layer, i.e., the mean effective thickness Leff and the mean relative deformation Da/a, on the annealing temperature, the maximum deformation being observed for ~300 °C. The results have allowed us to make a general assessment of the damaged layer condition after heat treatment

Effect of proton doping and heat treatment on the structure of single crystal silicon

The quality and structural perfection of single crystal silicon have been studied using double-crystal X-ray diffraction after hydrogen ion implantation and thermal annealing used in a number of semiconductor technologies. The fundamental difference of this approach is the possibility to rapidly obtain reliable experimental results which were confirmed using X-ray topography. Data have been presented for the condition of the damaged layer in n-type silicon single crystals (r = 100 W × cm) having the (111) orientation and a thickness of 2 mm after proton implantation at energies E = 200, 300 and 100 + 200 + 300 keV and dose D = 2 × 1016 cm-2 and subsequent heat treatment in the T = 100–900 °C range. Using the method of integral characteristics we have revealed a nonmonotonic dependence of the integral characteristics of the damaged layer, i.e., the mean effective thickness Leff and the mean relative deformation Da/a, on the annealing temperature, the maximum deformation being observed for ~300 °C. The results have allowed us to make a general assessment of the damaged layer condition after heat treatment

Comparative study of calcification in human choroid plexus, pineal gland, and habenula

Choroid plexus, pineal gland, and habenula tend to accumulate physiologic calcifications (concrements) over a lifetime. However, until now the composition and causes of the intracranial calcifications remain unclear. The detailed analysis of concrements has been done by us using X-ray diffraction analysis (XRD), X-ray diffraction topography (XRDT), micro-CT, X-ray phase-contrast tomography (XPCT), as well as histology and immunohistochemistry (IHC). By combining physical (XRD) and biochemical (IHC) methods, we identified inorganic (hydroxyapatite) and organic (vimentin) components of the concrements. Via XPCT, XRDT, histological, and IHC methods, we assessed the structure of concrements within their appropriate tissue environment in both two and three dimensions. The study found that hydroxyapatite was a major component of all calcified depositions. It should be noted, however, that the concrements displayed distinctive characteristics corresponding to each specific structure of the brain. As a result, our study provides a basis for assessing the pathological and physiological changes that occur in brain structure containing calcifications