* Permanent restoration of natural resources;
* High labor productivity when using;
* Low cost of electricity produced at the HPP;
* Integrated use of water resources for energy, irrigation, river transport, flood control, water supply, recreation and other purposes;
· The presence of low etiology in relation to complex technological equipment.
It is extremely important that the frequency of industrial damage arising from the use of hydroelectric power plants, including deaths, is significantly less compared to thermal power plants based on the amount of electricity produced in 1 kWh (taking into account fuel extraction and supply enterprises).
The saving of labor resources when using hydroelectric power plants is due to the following, including:
Incredibly high labor productivity compared to TEs;
high level of production automation;
the absence of labor costs for the extraction, supply, processing and disposal of fuel waste and, as a result, the number of working personnel used in the use of hydroelectric power plants will be approximately 12-15 times less than the number of working personnel at alternative facilities. The high economic efficiency of hydropower is due to the lack of a fuel component of electricity, slow wear of fixed assets, relatively low cost of wages, and the perfection of the technological process.
Integrated use of water resources. In the hydropower industry of the Republic of Uzbekistan, the reconstruction of transport routes in river networks, irrigation, industrial and municipal water supply and the development of fisheries are of great importance due to the reduction of the risk of major floods.
Integrated waterworks make a great contribution to solving the transport problem.
Reservoirs that appear during the construction of hydroelectric power plants lead to the fact that large areas of land are covered with water. Hydroelectric power plants account for a total of 1.2 million tons of destructive floods in the republic. close to hectares, with advanced development, multi-million residents help to reliably protect residential areas, as well as solve complex social and environmental problems.
1. Environmental problems
Reducing air pollution, especially carbon oxides, and preventing the "greenhouse effect" on the planet have become one of the problems of universal scale. The Republic of Uzbekistan also contributes to their resolution. One of the ways to reduce emissions in the energy sector is to develop areas without carbon fuels. Hydropower is an absolutely clean direction in this regard. In 2020, the electricity generated by hydroelectric power plants allowed to reduce electricity emissions by a quarter.
The technological process of hydropower production is environmentally hooligan. In the normal condition of the equipment, hydroelectric power plants practically do not emit harmful emissions into the environment. At the same time, the construction of hydropower facilities, in turn, will not show its impact on the environment.
During the construction of hydropower facilities, there is a complex impact on the environment. Reservoirs have the most serious effect – their appearance affects the ecological balance of soils and biocenoses. The effects shown can be both positive and negative.
The impact of reservoirs on the environment depends on their geographical location and categories (mountainous, foothill, plain), geological structure and hydrogeological determination of their banks with a channel, area, shape of appearance, size, depth of water discharge, system of use and other conditions.
As a result of the positive influence of reservoirs as flow coordinators, it becomes important to prevent water shortages for agricultural crops in the summer.
With the activation of natural processes in certain areas of the territories adjacent to them, after the creation of reservoirs, recreational changes occur in the landscapes, recreational zones and ecotourism are formed.
It is possible to list the following other aspects of the impact of reservoirs on the environment.
Floods in the upper part. In flooded areas, there is an increase in the groundwater level, and as a result, the land becomes swampy and unsuitable for agricultural use.
Changes in coastal forms the process of coordinating the flow and the rise and fall of water levels in the reservoir, which occur with this ratio, cause changes in the shape of the bottom with the coastal relief, which, in turn, reduces the size of the reservoir, leading to the accumulation of various rocks in it, the appearance of underwater shoals and the appearance of
Hydrological system. The process of reservoir construction and coordination of the water flow itself in the upper and lower parts of the basins causes changes in the gm hydrological system. Due to the expansion of the window area of the water surface, the volume of water evaporation increases sharply, resulting in the consumption of non-returnable water from the river. The hydrological system of the river is changing.
Climatic conditions. Changes in the flow of water and air, the appearance of waterlogged soils, shallow areas, well warmed by the sun at a depth of 1-1.5 m of reservoirs, create specific climatic conditions.
The influence of reservoirs on fauna (wildlife). All animals in the flood zone migrate to the territory marked by a high level. At the same time, their species composition and number are reduced in accordance with the rule. In some cases, reservoirs are the reason for the enrichment of fauna with new species of birds swimming in the water, fish and flora adapted to wet conditions.
Impact on the fish farm. It should be noted the following, namely:
The construction of a hydroelectric dam prevents the movement of fish to natural mating sites, in some cases fish-breeding devices do not always work satisfactorily;
the requirements that fishing imposes on the watercourse system turn out to be completely opposite to the tasks of coordinating flows, that is, the purpose of creating a reservoir – during the spring flood, shallow areas of the basin are drained at an earlier discharge of water, which negatively affects the mating of fish in the upper part of the reservoir daily
In order to create optimal conditions for fish mating, the transfer of water to the lower part of the pool is carried out subject to strict compliance with the requirements of fishing. In cases where it is possible to prevent damage, it is planned to build compensatory (covering) fish farming facilities (fish hatcheries, spawning farms).
It would be wrong to assume that all the impacts of reservoirs on the environment (in fact, in much greater numbers than those considered in Buer) will only be negative. Usually, each of them will have a set of positive properties, both negative and not so much.
Thus, it is also wrong to think that all forms of reservoir outcrops are inevitable and natural defects of hydraulic engineering. Many of these effects manifest themselves in the practice of creating and using reservoirs and turn out to be the consequences of incorrect design of objects or violation of the rules for the use of gyroscopes in general. For example, the harmful effects of reservoirs on fishing can be eliminated at a significant level by properly designing reservoirs and observing the appropriate level of their use.
Nature protection measures. When designing hydropower facilities, it is necessary to ensure that the damage to nature is at the lowest possible level. In order to control and timely prevent environmental pollution at the HPP, the following observations were established, namely:
· by draining and removing process oils;
· with the quality of the water to be disposed of after use;
· with ledges of elegaz puddles in complex switchgear.
In addition, taking into account the characteristics of large reservoirs with a complex and energy purpose, the following observations are carried out in them:
* Meteorological;
* hydrochemical;
· hydrobiological, including ichthyological observations.
According to the results of observations, the caretakers receive information about the necessary environmental measures.
When creating reservoirs, their water protection zone is assumed, protective forest plantations and reforestation measures are planned on the same territory. Contamination of the water protection zone by water flows into the reservoir prevents the ingress of substances.
Based on specially conducted scientific research, GES projects included the following extensive set of measures to protect flora and fauna, including:
· restoration of forests instead of flooded woodlands, relocation of rare, relict and Red-listed plants from flooded areas;
* cultivation of valuable varieties in crop rotation; introduction of a system of special permits that do not allow the basin to build up its lower part;
* moving to catch valuable animal species from flooded areas;
* creation of livestock farms and livestock farms for breeding animals; Organization of protective and reserve zones; construction of fishing, fish-breeding and compensation facilities.
LITERATURE
1. Orgo V. M. Fundamentals of designing and calculating the strength of hydraulic turbines. L.: Mechanical Engineering, 1978. 224 p.
2. Barlit V. V. Hydraulic turbines. Kiev: Vishcha shkola, 1977. 360 p.
3. Zavyalov Yu. S., Kvasov B. I., Miroshnichenko V. A. Methods of spline functions. M.: Nauka, 1980. 352 p.
4. Zavyalov Yu. S., Leus V. A., Skorospelov V. A. Splines in engineering geometry. Moscow: Mashinostroenie, 1985. 221 p.
5. Zalgaller V. A. Theory of envelopes. M.: Nauka, 1975. 104 p. References.
6. Salomov U., Yusupov S., Odilov O., Moydinov D. Theoretical Substantiation of the Advisability of Using Adhesives When Sealing the Core of Car Radiators and Diagnosing Radiators with a Thermal Load. nternational Journal of Engineering Trends and Technology. Volume 70 Issue 1, 81—92, January, 2022 ISSN: 2231 – 5381 /doi:10.14445/22315381/IJETT-V70I1P210.
7. Abramov A. I., Ivanov-Smolensky A.V. Design of hydrogenerators and synchronous compensators. Moscow: Higher School, 1978.
8. Avakian A. B., Sharapov V. A. Reservoirs of hydroelectric power plants of the Russian Federation. Moscow: Energiya, 1977.
9. Arshenevsky N. N. Reversible hydraulic machines of pumped storage power plants. Moscow: Energiya, 1977.
10. Arshenevsky N. N., Pospelov B. B. Transients of large pumping stations. Moscow: Energiya, 1980.
11. Asarin A. E., Bestuzheva K. N. Water-energy calculations. Moscow: Energoatomizdat, 1986.
12. Baburin B. L., Fine I. I. Economic justification of hydropower engineering.. M.: Energy, 1975.
SPATIALLY OSCILLATING PHOTOVOLTAIC CURRENT IN AN OPTICALLY ACTIVE FERROELECTRIC SbSI
Karimov Sherzod Bahodirovich
Candidate of the Faculty of Physics and Technology of Fergana State University
Aliev Ibratjon Khatamovich
2nd year student of the Faculty of Mathematics and Computer Science of Fergana State University
Karimov Bahodir Khoshimov
Candidate of Physical and Mathematical Sciences, Faculty of Physics and Technology, Fergana State University
Ferghana State University, Ferghana, Uzbekistan
Аннотация. В настоящей работе обнаружен и исследованы пространственно-осциллирующей фотовольтаический ток (ПОФТ) в направлении [100] в сегнетоэлектрике SbSJ при освещении поляризованным светом в направлении [010] и образованию от оптической зависимости в [001] направлении структуры пространственного осциллирующего фотовольтаического тока Jx. Обсуждены некоторые экспериментальные и физические основы пространственно осциллирующего фотовольтаического тока.
Ключевые слова: сегнетоэлектрик, поляризация, оптически-активный кристалл, пространственно-осциллирующий фотовольтаический ток, тензор 3-ранга.
Annotation. In this paper, the spatially oscillating photovoltaic current (POFT) in the direction [100] in the SbSJ ferroelectric is detected and investigated when illuminated with polarized light in the direction [010] and the formation of the structure of the spatial oscillating photovoltaic current Jx from the optical dependence in the direction [001]. Some experimental and physical bases of spatially oscillating photovoltaic current are discussed.
Keywords: ferroelectric, polarization, optically active crystal, spatially oscillating photovoltaic current, rank 3 tensor.
In recent years, it has become clear that in thermodynamic nonequilibrium conditions, currents of a different nature are possible due to the absence of a center of symmetry medium. The most important of this class of effect is the anomalous photovoltaic effect (AF effect).
The AF effect is that with uniform illumination of a short-circuited ferroelectric, a stationary current flows through it, which in [1,2] was called photovoltaic. It has been shown that it is the photovoltaic current that leads to the anomalous photovoltaic effect (AF effect) in ferroelectrics.
The anomalous photovoltaic effect discovered for ferroelectrics for the first time in [1,2] is a special case of a more general AF effect described for crystals without a center of symmetry by the third rank aijk tensor [3].
According to (1), with uniform illumination by linearly polarized light of homogeneous crystals without a center of symmetry (ferroelectric or piezoelectric crystal), a photovoltaic current Ji arises in it, the sign and magnitude of which depend on the orientation of the polarization vector of light with projections Ej, Ek*.
The components of the aijk tensor are nonzero for 20 acentric symmetry groups. If the electrodes of the crystal are opened, the photovoltaic current Ji generates photovoltaic voltages
where σt and σf, respectively, are the dark and photoconductivity, l is the distance between the electrodes. The generated photovoltage is of the order of 103—105 V, thus exceeding the value of the band gap Eg by two to four orders of magnitude.
In accordance with (1) and the symmetry of the point group of the crystal, expressions can be written for the photovoltaic current Ji. Comparison of the experimental angular dependence of Ji (β) with (1) makes it possible to determine the photovoltaic tensor aijk or photovoltaic coefficient
a* is the light absorption coefficient.
As shown by Belinicher [4], depending on the shape of the optical indicatrix and the direction of propagation of plane polarized light in the crystal, there may be directions for which the photovoltaic current (1) is spatially oscillating. In this case:
where ne, n0 are the refractive indices of ordinary and extraordinary rays, Ee and E0* are the projections of the polarization vector of light on the optical axes of the crystal,
In this case, the photovoltaic current (2) oscillates in the crystal with a period of
As indicated in [4] and as can be seen from (2), a spatially oscillating photovoltaic current (SWEAT) can be experimentally observed under conditions of strong light absorption.
where α* is the absorption coefficient.
1. SPATIALLY OSCILLATING PHOTOVOLTAIC CURRENT IN SbSi FERROELECTRIC
In this paper, a spatially oscillating photovoltaic current (POFT) in the direction [100] in the SbSI ferroelectric is detected and investigated when illuminated with polarized light in the direction [010].
Antimony sulfoiodide (SbSI) belongs to the class of chalcogenides of metals of the fifth group AVBVICII, where A-Sb; Bi; B-S, Se, Te; C-CL, Br, I. SbSI and SbSIxBr1-x crystals are biaxial, have a large double refraction, below temperature. Curie Tc=220C SbSI crystals belong to the mm2 class and have rhombic symmetry. During the phase transformation, the center of symmetry disappears, therefore, SbSI crystals become ferroelectrics below the transition point.
The phase transition at 220C was registered for the first time by Fatuzzo [5] with a change in the temperature dependence of the dielectric constant. Crystals have pronounced semiconductor properties, their photovoltaic properties are well studied [1].
Measurements were carried out for SbSI single crystals in the ferroelectric phase at a temperature of T = 133 K. The crystal was illuminated by plane polarized light using a xenon lamp and a ZMR monochromator. The stationary photovoltaic current J was measured by the method previously described [1]. In accordance with the SbSI symmetry (point group mm2), when measuring Jz (z is the direction of spontaneous polarization) and illuminating the crystal in the x and y directions, POFT does not occur. The expression for the photovoltaic current Jz when illuminated in the x and y directions, respectively, has the form:
where I is the light intensity, β is the angle between the plane of polarization of light and the z axis. In Fig.1, curve 1 represents the experimental angular dependence of Jz (β) for λ=600 nm when illuminated along [100]. From the comparison of the experimental angular dependences of Jz (β) with (4) and (5), the numerical values of αιjκ or photovoltaic coefficients were estimated
Taking into account pleochroism and anisotropy of light reflection in SbSI [6], the following values were obtained:
K314*10—8; K323*10—8; K33 (2—3) *10—8A*cm* (W) -1. Thus, in SbSI, the photovoltaic coefficients K31, K32, K33 are more than an order of magnitude higher than the corresponding coefficients in LiNbO3: Fe.
Fig.1. Dependence of the photovoltaic current Jz (1) at l = 600 nm and Jx (2) at l = 460 on the orientation of the plane of polarization of light in SbSI.
According to (2), for SbSI, the photovoltaic current components are spatially oscillating. However, when the crystal is illuminated in the region of strong absorption in the direction of the x or y axes and when condition (3) is met, currents flow along the surfaces (100) and (010), respectively.
where β is the angle between the plane of polarization of light and the z axis. According to [1,7] for SbSI, the strong absorption condition (3) should be fulfilled already at λ470 nm. To observe the POFT under conditions of strong absorption, silver electrodes in the form of bands parallel to the axis of spontaneous polarization z were sprayed onto the face of the cinacoid (010). Using these electrodes, when the crystal was illuminated in the direction [010] by polarized light with λ=460 nm, the current Jx curve 2 was measured and the current Jz was measured in the long-wavelength region (λ=600nm, curve 1).The angular dependence of the measured current satisfies (5), while the Oh current in this region cannot be observed at all due to violation of condition (3) and spatial oscillation. Figure 2 shows the spectral Jz (curve 1), Jx (curve 2), attributed to the unit of incident energy, as well as the spectral dependence
constructed taking into account the dispersion of n0, pe and the absorption coefficient α* in the [010] direction.
Angular dependence Jx (β) in the form of curve 2, which agrees well with (7) at K15= (2—4) ·10—9A·cm· (W) -1 (λ=460nm).
Fig. 2. Spectral dependence of Jz (1), Jx (2) and L=l0a* (3).
While the spectral dependence measured earlier in is monotonic, the spectral dependence of Jx detects a sharp maximum near L1. Thus, the decline of Jx in the long-wave region, where L <<1, is due to POFT. The decline of Jx in the short wave region, where L> 1, is interesting.Since the AF effect is not related to the lifetime of nonequilibrium carriers, it is possible that this short-wave decline of Jx is due to a decrease in K15 and, consequently, mobility in the direction [100].
2. SPATIALLY OSCILLATING PHOTOVOLTAIC CURRENT IN A FERROELECTRIC α-HgS
The paper considers photovoltaic effects in optically active α-HgS crystals. Some experimental and physical bases of the photovoltaic effect in active crystals are discussed.
Mercury sulphide HgS exists in two modifications: the black modification – metacinnabarite (β-HgS) – crystallizes in a cubic system (point group 3m), the red modification—cinnabarite or cinnabar (α-HQs) – crystallizes in a trigonal system (point group 32).
Red cinnabar crystals with a particularly large specific rotation along the optical axis for the red rays transmitted by them r= 2350/mm were studied in this work. Α – HgS crystals grown by the hydrothermal method in the Laboratory of Hydrothermal Synthesis at the Institute of Crystallography of the Russian Academy of Sciences were studied. The starting materials for the manufacture of cinnabarite were pure mercury in sulfur. Electrical, electro-optical properties of α-HgS crystals and photoelectric properties of crystals were studied in [5,6].
It is shown that the optical activity of the α-HgS crystal has a stronger effect on the angular distribution of the photovoltaic current measured in linearly polarized light.
Fig. 3. shows the orientation dependence of the photovoltaic current Jx (β) in α-HgS. In accordance with (1) and the symmetry of the point group 32, the expression for Jx (β) when illuminated in the direction of the y axis has the form
where is the angle between the plane of polarization of light and the x—axis.
Comparison of the experimental angular dependence of Jx (β) with (2) gives
K11= (1—2) *10—9A* cm * (W) -1 (T=133 Κ, λ=500nm). The coincidence of the experimental angular dependence of Jx (β) with (2) shows that in the region of strong absorption (λ=500nm, α*>> 100cm-1), the effect of optical activity in the direction of the y axis on the angular distribution of Jx (β) is insignificant.The effect of optical activity in the z-direction was found when studying the angular dependence of Jx (β) in various spectral regions (Fig.1).The effect of optical activity in the z-direction was found when studying the angular dependence of Jx (β) in various spectral regions (Fig.1).The effect of optical activity in z- The angular dependence of Jx (β) in various spectral regions was discovered during the study of the angular dependence of Jx (β) in various spectral regions (Fig. 1).
In accordance with (1), the angular dependence of Jx (β) illumination in the z – direction (the z axis coincides with the axis of symmetry of the third order) has the form.
where β is the angle between the plane of light polarization and the y axis.
Figure 2 indicates a good correspondence between the experimental dependence of Jx (β) and (3) in the region of strong light absorption (λ= 400nm).The transition from the short-wave to the long-wave region, corresponding to a decrease in α*, changes the nature of the angular dependence of Jx (β) and its amplitude.The transition from the short-wave to the long-wave region, corresponding to a decrease in α*, changes the nature of the angular dependence of Jx (β) and its amplitude.
Fig.3. Orientation dependence of the photovoltaic current Jx (β) in a-HgS (T=1330K).
Figure 4 shows the spectral-angular diagram of the photovoltaic current Jx. Obviously, its shape is determined by its optical activity in the z-direction, its spectral dispersion, as well as the spectral distribution of the photovoltaic effect in α-HgS.
The optical dependence in the z – direction thus leads to the formation of the structure of the spatial oscillating photovoltaic current Jx. The photovoltaic current oscillates in the z-direction with a period of
Where χ is the optical activity coefficient.
The angular dependence of Jx (β) coincides with (3) only under the condition of strong light absorption
where α* is the light absorption coefficient.
Fig. 4. Spectral – angular diagram of photovoltaic current in a-HgS (T=1330K). The direction of light propagation is indicated in the upper part of the figure.
Note: The Board of Authors thanks V. A. Kuznetsov for providing the crystals and V. M. Fridkin for the discussion.
Literature
1. Glass A.M.Van der Liebe D. Herren T.J. High- voltage Bulk Photovoltaic effect and the Photorefractive process in Limbo. //J. Appl. Phys. Lett. 1974. N4 (25) p.233-236.
2.Fridkin V.M., Photosegnetoelectrics. M., Nauka, 1979, pp.186-216.
3.Belinicher V. I. Studies of photovoltaic effects in crystals. Diss. for the job application. Doctor of Physical and Mathematical Sciences. Novosibirsk. 1982. 350 P.
4. Sturman B. I., Fridkin V. M. Photovoltaic effects in media without an inversion center. -M., Nauka.1992. -p-208.
5. Efremova E. P., Kuznetsov V. A., Kotelnikov A. R. Crystallization of cinnabar in hydrosulfide solutions. // J. Crystallography. 1976. vol.21. v.3. pp.583—586.
6. Donetskikh V. I., Sobolev V. V. Reflection spectra of trigonal HgS. // J. Optics and spectroscopy. 1977. vol.42. v.2. pp.401—403.
7.Fridkin V. M. Volumetric photovoltaic effect in crystals without a center of symmetry. // Crystallography. 2001. Vol. 46, N 4. pp. 722—726.
РОЛЬ РЕЗОНАНСНЫХ ЯДЕРНЫХ РЕАКЦИЙ В СОВРЕМЕННОЙ ЭНЕРГЕТИКЕ. THE ROLE OF RESONANT NUCLEAR REACTIONS IN MODERN ENERGY
Жалолов Ботирали Рустамович
Генеральный директор «Clipper Energy» LLC и «Clipper Associates» Corp
«Clipper Energy» LLC, «Clipper Associates» Corp., Malaysia
Каримов Боходир Хошимович
Кандидат физико-математических наук, доцент физико-технического факультета Ферганского государственного университета
Алиев Ибратжон Хатамович
Студент 2-курса факультета математики-информатики Ферганского государственного университета
Ферганский государственный университет, Фергана, Республика Узбекистан
Zhalolov Botirali Rustamovich
General Director of «Clipper Energy» LLC and «Clipper Associates» Corp
«Clipper Energy» LLC, «Clipper Associates» Corp., Malaysia
Karimov Bahodir Khoshimov
Candidate of Physical and Mathematical Sciences, Associate Professor of the Faculty of Physics and Technology of Fergana State University
Aliev Ibratjon Khatamovich
2nd year student of the Faculty of Mathematics and Computer Science of Fergana State University
Ferghana State University, Ferghana, Republic of Uzbekistan
Аннотация. Современную энергетику просто невозможно представить без составляющей в лице атомных электростанций, в основе которых лежат явления распада урана-238 и урана-235, в том числе с использованием саморазмножающихся методов деления. Но как известно источники не вечны, по этой причине важно нахождение нового способа по выделению максимально большого количества электрической энергии и, если верить результатам современных исследований, явным кандидатом на подобный титул могут стать резонансные ядерные реакции, которые изучаются на основе совершенно новой науки – физики резонансных ядерных реакций (ФРЯР).
Ключевые слова: физика резонансных ядерных реакций, энергетическая составляющая, кулоновский барьер, ядерные реакций, физика атомного ядра и элементарных частиц, ядерное эффективное сечение, длина волны.
Annotation. It is simply impossible to imagine modern energy without a component in the face of nuclear power plants, which are based on the decay phenomena of uranium-238 and uranium-235, including using self-multiplying fission methods. But as you know, the sources are not eternal, for this reason it is important to find a new way to release as much electrical energy as possible and, if you believe the results of modern research, resonant nuclear reactions, which are studied on the basis of a completely new science – physics of resonant nuclear reactions (PRNR), can become a clear candidate for such a title.
Keywords: physics of resonant nuclear reactions, energy component, Coulomb barrier, nuclear reactions, physics of atomic nucleus and elementary particles, nuclear effective cross section, wavelength.
А. Русская версия
1. Общие понятия ядерных реакций
Сама по себе ядерная реакция, это процесс взаимодействия атомного ядра с другим ядром или элементарной частицей, которая может сопровождаться изменением структуры, строения, состава ядра, образованием новых ядер или элементарных частиц и введением дальнейших изменений. Также последствием ядерной реакции может стать его деление, спускание как элементарных частиц, так и безмассовых протонов. Вместе с этим, из-за действия несколько иных законов, при которых масса активно может превращаться в энергию и обратно, кинетическая энергия результирующих частиц вполне, может быть, не равна сумме изначальных.
Подобные ядерные реакции являются экзо-энергетическими или выделяющими энергию. Первая ядерная реакция была проведена Эрнестом Резерфордом в 1917 году, при бомбардировке альфа-частицами ядра атомов азота. Она была полностью зафиксирована благодаря появлению вторичных ионизирующих частиц, пробег коих в газе был больший чем пробег альфа-частиц, после чего и были идентифицированы как протоны. Процесс же позже был сфотографирован.
К слову, об этом, важно сказать, что для фотографирования ядерных реакций используется камера Вильсона. Говоря же о механизмах взаимодействия, то можно выделить два вида такого взаимодействия, а именно:
1. Реакция с образованием составного ядра, этот процесс состоит из двух стадий, при этом налетающая частица соединяется с самим бомбардируемым ядром, составляя общее ядро, которое позже распадается. Такая ядерная реакция протекает на небольших энергиях, до 10 МэВ;
2. Прямые ядерные реакции, проходящие уже сразу, за ядерное время, которое составляет мельчайшие доли секунды и рассчитываются исходя из иных факторов, одним из которых является время пересечения ядра частицей. Главным образом такой вид реакции выражается лишь на очень больших энергиях бомбардирующих частиц.
В случае сохранения первоначальных ядер после самой ядерной реакции, также не рождаются новые частицы, то реакция считается упругим рассеянием в поле ядерных сил, без какого-либо внутреннего взаимодействия. Такая реакция сопровождается лишь передачей кинетической энергии и импульса одной налетающей частицы ядру-мишени, называясь потенциальным рассеянием и полноценно подчиняясь законам сохранения импульса в этом случае.
Ранее были упомянуты механизмы реакции, но стоит несколько подробнее на них остановиться. Первая реакция, а именно механизм составного ядра был впервые разработан и предложен Нильсом Бором в 1936 году совместно с знаменитой теорией капельной модели. Данная теория даже сегодня лежит в основе больших представлений о всех ядерных реакциях.
Если следовать данной теории, то как и было описано, ядерная реакция следует в два этапа, при этом весь процесс от столкновения, образования составного ядра и его распада занимает в рамках 10-23-10-21 с. И важно отметить, что какое бы не было составное ядро, оно всегда является возбуждённым из-за избыточной энергии, которая вносится частицей в лице энергии связи нуклонов в составном ядре и части кинетической энергии составного ядра, которая равна сумме кинетической энергии ядра-мишени с определённым большим массовым числом и налетающей частицы в системе так называемого центра инерции.
Здесь важно определить такое понятие как энергия возбуждения составного ядра, которое образовалось при поглощении свободного нуклона. Она составляет сумме энергии связи нуклонов ядра-мишени и части его кинетической энергии (1).
Часть кинетической энергии из-за большой разницы в массах ядра и нуклона в таких случаях становится равной кинетической энергии бомбардирующего нуклона. В среднем же энергия связи равна 8 МэВ и может изменяться только при отличительных особенностях образуемого в этом процессе составного ядра, но для точно указанного ядра-мишени и нуклона, это значение – константа. Кинетическая же энергия частицы может быть какой угодно, к примеру, в ядерных реакциях, где налетает нейтрон, за счёт того, что отсутствует отталкивающая сила ядра – кулоновский барьер, их энергия может быть крайне близка к нулю.
Таким образом, кинетическая энергия является минимальной энергией возбуждения составного ядра.
И именно из утверждения наличия составного ядра и существованию каналов распада ядер, можно сделать вывод о существовании каналов реакций. Сами по себе каналы реакции – это способы перехода из возбуждённого в невозбуждённое состояние. Типа и квантовое состояние налетающих частиц и ядер до начала реакции определяют входной канал ядерной реакции, после завершения же реакции совокупность образовавшихся частиц, то есть продуктов реакции и их квантовое состояние определяется результирующий выходной канал реакции. Полная характеристика ядерной реакции осуществляется входными и выходными каналами.
Составное ядро само по себе живёт довольно долгое время, благодаря чему сам выбор канала реакции вовсе не зависит от способа образования составного ядра, благодаря чему оно «забывает», как было образовано. Это становится причиной для утверждения независимости процессов организации составного ядра и его распада. Ярким примером может быть ситуация образования возбуждённого ядра алюминия-27 следующими способами (2).
Но распадается это яро одинаково во всех случаях, при условии одинаковой энергии возбуждения. Но при этом имеется и возможно распада обратным любой из этих реакций, с определённой вероятностью, не зависящей от истории возникновения самого возбуждённого ядра. Если же говорить о вероятности таких событий, то зависимость становится между сортом ядра-мишени и энергий.
Как и было ранее указано, ядерные реакции могут также протекать и по прямому каналу взаимодействия при больших энергиях, поскольку нуклоны ядра можно рассматривать как свободные. Отличие от предыдущей модели составного ядра от модели прямых реакции состоит изначально в распределении векторов импульсов частиц-продуктов ядерной реакции, относительно импульса бомбардирующих частиц. Если же в составной модели действует сферическая симметрия, то в данном случае геометрия более проста и преимущество в выборе направлений результирующими частицами состоит в направлении входящих частиц.
Ранее упоминалось понятие вероятности ядерной реакции, которая представляется величиной, которая называется эффективным сечением ядерной реакции. В лабораторной системе отчёта принимается ситуация покоя ядра-мишени, вероятность взаимодействия определяется произведением сечения на поток падающих частиц, при этом сечение выражается в единицах площади, а поток в количестве частиц, пересекающих единицу площади в единицу времени. Само сечение ядерной реакции исчисляется в крайне малых единицах площади – барнах, равных 10—24 см2.
Отношение случаев реакции, отнесённое к числу бомбардировавших мишень частиц, называется выходом ядерной реакции. Эта величина определяется экспериментально при количественных измерений, что связано с сечением реакций, а измерение этого выхода в самой сути – измерения сечения реакции.
