In this work the study on the peculiarities of multiparticle production in interactions of asymmetric nuclei to search for unusual features of such interactions, is performed. A research of long-range and shortrange multiparticle correlations in the pseudorapidity distribution of secondary particles on the basis of analysis of individual interactions of nuclei of 197 Au at energy 10.7 AGeV with photoemulsion nuclei, is carried out. Events with long-range multiparticle correlations (LC), short-range multiparticle correlations (SC) and mixed type (MT) in pseudorapidity distribution of secondary particles, are selected by the Hurst method in accordance with Hurst curve behavior. These types have significantly different characteristics. At first, they have different fragmentation parameters. Events of LC type are processes of full destruction of the projectile nucleus, in which multicharge fragments are absent. In events of mixed type several multicharge fragments of projectile nucleus are discovered. Secondly, these two types have significantly different multiplicity distribution. The mean multiplicity of LC type events is significantly more than in mixed type events. On the basis of research of the dependence of multiplicity versus target-nuclei fragments number for events of various types it is revealed, that the most considerable multiparticle correlations are observed in interactions of the mixed type, which correspond to the central collisions of gold nuclei and nuclei of CNO-group, i.e. nuclei with strongly asymmetric volume, nuclear mass, charge, etc. Such events are characterised by full destruction of the target-nucleus and the disintegration of the projectile-nucleus on several multi-charged fragments.
Tin dioxide thin films were obtained by centrifuging. Annealing of samples was carried out in a muffle furnace at a temperature of 400 °C for 15 min, 3, 6 and 12 h. The surface resistance of the films was measured by four-force method. The sensitivity to ethanol vapour was determined by experimental setup that allows measurements in the range from room temperature to 300 °C. There is a change in the acidity of the solution with the addition of ammonium fluoride. To take into consideration this change in acidity, three batches of solutions were prepared: one example without additives, another one ‒ with the addition of ammonium fluoride and the last one ‒ with the addition of ammonium hydroxide. Films synthesized from a film-forming solution containing NH4F have less resistance than films obtained from solutions that do not contain ammonium fluoride. This confirms the presence of fluorine ions in the films as additional sources of free charge carriers. It is found that the pH-indicator of the film-forming solution does not affect the surface resistance of the synthesized SnO2 films. Annealing of fluoride doped films leads to an increase in surface resistance by two orders of magnitude, which is associated with the removal of fluorine from the films and the formation of a large number of defects. Further annealing leads to a decrease in surface resistance, which seems to be associated with a decrease in defects. It is shown that the change in the hydrogen index of the film-forming solution leads to the formation of films with a thermally stable sensitivity to ethanol vapour.
Аннотация. Тонкие пленки оксида олова получали из пятиводного тетрахлорида олова растворением в 97% этаноле. Концентрация ионов олова в пленкообразующей системе была 0,12 моль/л, 0,16 моль/л, 0,2 моль/л. Пленкообразующую систему SnCl 4 /EtOH наносили на поверхность стеклянных подложек модифицированным методом окунания. Сушили на воздухе и затем отжигали при 400 о С. Было нанесено 4 слоя. Обработка водородной плазмой проводилась при давлении 6,5 Па, мощности 20 Ватт, частоте колебаний создаваемых генератором 27,12 МГц0,6%. Обнаружено уменьшение прозрачности,в пределах точности измерений, пленок, полученных из пленкообразующей системы с концентрацией ионов олова 0,12 моль/л и 0,2 моль/л. Прозрачность пленок, полученных из пленкообразующей системы с концентрацией ионов олова 0,16 моль/л уменьшилось на 3%. Сопротивление пленок уменьшилось в 1,5 раз. Рентгеноструктурный анализ показал рост интенсивности дифракционных пиков от плоскостей кристаллитов SnO 2 . Получен важный технический результат: уменьшение сопротивления тонких пленок SnO 2 без значительного уменьшения прозрачности, при использовании пленкообразующей системы с концентрацией ионов олова 0,12 моль/л и 0,2 моль/л после обработки в течение 3 минут в водородной плазме.Ключевые слова: тонкие пленки, диоксид олова SnO 2 , обработка плазмой, водородная плазма, сопротивление пленок, коэффициент пропускания.
This paper considers the effect of oxygen and hydrogen plasma on SnO2 films synthesized from solutions of tin tetrachloride containing NH4F and NH4OH additives. It was found that the treatment of samples with oxygen plasma for 5 min led to a decrease in transparency by 1.11 and 1.17 times. On the transmission spectra, a decrease in the transmittance at a wavelength of 450 nm to 38.1% (1.24 times) in samples obtained from solutions with the addition of NH4F and up to 29.9% (1.53 times) in samples obtained from solutions with the addition of NH4OH is observed. The formation of tin oxide (II) under the influence of the reducing properties of hydrogen plasma is assumed. At the same time, the formation of metal tin from tin dioxide is not observed here. Due to the decreasing of transmission coefficient in the long-wave region of the spectrum. There is an increase in surface resistance after treatment with oxygen plasma, due to filling oxygen vacancies. Treatment of hydrogen plasma films leads to a decrease in surface resistance. Perhaps due to the increase in oxygen vacancies under the influence of hydrogen plasma. Within five minutes, the oxygen and hydrogen plasma had a more active effect on the films obtained from the solution with the addition of ammonium hydroxide, which is associated with a higher porosity of the sample. Consequently, irrespective of the time of plasma exposure with increasing the surface of contact between ionized gases and the film material, the interaction efficiency will increase.
В работе рассмотрено влияние кислотности пленкообразующих растворов на структуру и оптические свойства тонких пленок SnO 2 , полученных золь-гель методом. Для исследования была приготовлена серия растворов с концентрацией ионов олова 0,12 моль/л с добавлением различного количества концентрированного водного раствора аммиака. Водный раствор аммиака использовался для регулирования уровня pH в системе SnCl 4 /C 2 H 5 OH. Растворы наносились на подложки модифицированным методом окунания. Пленка наносилась на одну сторону подложки. Образцы сушились на воздухе не менее 30 минут, затем отжигались в муфельной печи при 400 о С в течение 15 минут. Структуру пленок изучали с помощью оптического микроскопа МПЭ-11. Спектры пропускания измерялись на двулучевом спектрофотометре СФ-256 УВИ (диапазон длин волн 190-1200 нм.). В ходе эксперимента выявлена прямая зависимость образования структур на поверхности полученных пленок от кислотности исходных растворов. При увеличении уровня pH наблюдается рост структур и изменение их формы. Полученные результаты расширяют фундаментальные знания в области разработки способов управления структурой тонких пленок SnO 2 , что является важным элементом при создании материалов с улучшенными функциональными свойствами. Ключевые слова: тонкие пленки, диоксид олова SnO 2 , золь-гель метод, кислотность, структура поверхности, спектры пропускания.
A study of characteristics of the events of complete destruction of the projectile nucleus in the interactions between asymmetric nuclei for different initial states of the collision, is performed. In the interactions of the sulfur nuclei with heavy emulsion nuclei at energy 200 AGeV, anomalous high number of events the complete destruction of the projectile nuclei, is observed. The high probability of such events depends on the energy of interaction (it is not detected in the interactions of the sulfur nuclei with emulsion nuclei at energy of 3.7 AGeV), on the degree of asymmetry of the interacting nuclei (it is not detected in interactions of the sulfur nuclei with light emulsion nuclei) and on initial state of interaction (it is not detected in peripheral collisions). These events are characterized by high multiplicity of secondary particles and narrow angular distribution at large angles (they form narrow peak in the region of small values of average pseudorapidity).
Abstract. In this work the study on the peculiarities of multiparticle production in interactions of asymmetric nuclei to search for unusual features of such interactions, is performed. A research of long-range and shortrange multiparticle correlations in the pseudorapidity distribution of secondary particles on the basis of analysis of individual interactions of nuclei of 197 Au at energy 10.7 AGeV with photoemulsion nuclei, is carried out. Events with long-range multiparticle correlations (LC), short-range multiparticle correlations (SC) and mixed type (MT) in pseudorapidity distribution of secondary particles, are selected by the Hurst method in accordance with Hurst curve behavior. These types have significantly different characteristics. At first, they have different fragmentation parameters. Events of LC type are processes of full destruction of the projectile nucleus, in which multicharge fragments are absent. In events of mixed type several multicharge fragments of projectile nucleus are discovered. Secondly, these two types have significantly different multiplicity distribution. The mean multiplicity of LC type events is significantly more than in mixed type events. On the basis of research of the dependence of multiplicity versus target-nuclei fragments number for events of various types it is revealed, that the most considerable multiparticle correlations are observed in interactions of the mixed type, which correspond to the central collisions of gold nuclei and nuclei of CNO-group, i.e. nuclei with strongly asymmetric volume, nuclear mass, charge, etc. Such events are characterised by full destruction of the target-nucleus and the disintegration of the projectile-nucleus on several multi-charged fragments.
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