High pure substances for astrophysical research
The features of the application of high-purity substances for studying rare nuclear events in astrophysics, in particular double beta decay, are considered. It was noted that for such studies, the special underground laboratories are needed to eliminate the cosmic radiation background, and the u...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
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Kovtun, G.P. 2023-11-22T15:26:10Z 2023-11-22T15:26:10Z 2020 High pure substances for astrophysical research / G.P. Kovtun // Problems of Atomic Science and Technology. — 2020. — № 1. — С. 8-11. — Бібліогр.: 8 назв. — англ. 1562-6016 PACS: 23.40.-s; 29.40.Mc; 81.20.Ym https://nasplib.isofts.kiev.ua/handle/123456789/194338 The features of the application of high-purity substances for studying rare nuclear events in astrophysics, in particular double beta decay, are considered. It was noted that for such studies, the special underground laboratories are needed to eliminate the cosmic radiation background, and the use of high-purity materials for possibility to record rare nuclear events. The content of neutral impurity elements should not exceed 0.1 ppm, and the level of radionuclide contamination should be less than units mBq/kg. At the NSC KIPT, the technologies have been developed for the production of high-purity refractory (W, Mo, Re, Ru, Os) and low-melting metals (Zn, Cd, Te, archPb), including isotopically-enriched ¹⁰⁶Cd, ¹¹⁶Cd, satisfying these requirements. Using these metals both as individual elements and as part of low-background scintillation single crystals, it was possible to obtain a number of new fundamental results in the field of astrophysics, together with the Institute for Nuclear Research of the National Academy of Sciences of Ukraine and the Gran Sasso Laboratory of the National Institute of Physics (Italy). Розглянуто особливості застосування високочистих речовин для дослідження рідкісних ядерних подій в астрофізиці, зокрема подвійного β-розпаду. Відзначено, що для проведення подібних досліджень необхідні спеціальні підземні лабораторії для усунення фону космічних випромінювань і застосування високочистих матеріалів для можливості реєстрації рідкісних ядерних подій. Вміст нейтральних домішкових елементів при цьому не повинен перевищувати 0,1 ррm, а рівень радіонуклідного забруднення – менше одиниць мБк/кг. У ННЦ ХФТІ були розроблені технології отримання високочистих тугоплавких (W, Mo, Re, Ru, Os) і легкоплавких (Zn, Cd, Тe, apxPb) металів, у тому числі ізотопно-збагачених ¹⁰⁶Cd, ¹¹⁶Cd, що задовольняють цим вимогам. З використанням цих металів як у вигляді окремих елементів, так і в складі низькофонових сцинтиляційних монокристалів спільно з Інститутом ядерних досліджень НАН України та лабораторією Гран-Сассо Національного інституту фізики (Італія) вдалося отримати ряд нових принципових результатів у галузі астрофізики Рассмотрены особенности применения высокочистых веществ для исследования редких ядерных событий в астрофизике, в частности двойного β-распада. Отмечено, что для проведения подобных исследований необходимы специальные подземные лаборатории для устранения фона космических излучений и применение высокочистых материалов для возможности регистрации редких ядерных событий. Содержание нейтральных примесных элементов при этом не должно превышать 0,1 ррm, а уровень радионуклидного загрязнения – менее единиц мБк/кг. В ННЦ ХФТИ были разработаны технологии получения высокочистых тугоплавких (W, Mo, Re, Ru, Os) и легкоплавких (Zn, Cd, Те, apxPb) металлов, в том числе изотопно-обогащенных ¹⁰⁶Cd, ¹¹⁶Cd, удовлетворяющих этим требованиям. С использованием этих металлов как в виде отдельных элементов, так и в составе низкофоновых сцинтилляционных монокристаллов совместно с Институтом ядерных исследований НАН Украины и лабораторией Гран-Сассо Национального института физики (Италия) удалось получить ряд новых принципиальных результатов в области астрофизики. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Pure materials and the vacuum technologies High pure substances for astrophysical research Високочисті речовини для астрофізичних досліджень Высокочистые вещества для астрофизических исследований Article published earlier |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| title |
High pure substances for astrophysical research |
| spellingShingle |
High pure substances for astrophysical research Kovtun, G.P. Pure materials and the vacuum technologies |
| title_short |
High pure substances for astrophysical research |
| title_full |
High pure substances for astrophysical research |
| title_fullStr |
High pure substances for astrophysical research |
| title_full_unstemmed |
High pure substances for astrophysical research |
| title_sort |
high pure substances for astrophysical research |
| author |
Kovtun, G.P. |
| author_facet |
Kovtun, G.P. |
| topic |
Pure materials and the vacuum technologies |
| topic_facet |
Pure materials and the vacuum technologies |
| publishDate |
2020 |
| language |
English |
| container_title |
Вопросы атомной науки и техники |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| format |
Article |
| title_alt |
Високочисті речовини для астрофізичних досліджень Высокочистые вещества для астрофизических исследований |
| description |
The features of the application of high-purity substances for studying rare nuclear events in astrophysics, in
particular double beta decay, are considered. It was noted that for such studies, the special underground laboratories
are needed to eliminate the cosmic radiation background, and the use of high-purity materials for possibility to
record rare nuclear events. The content of neutral impurity elements should not exceed 0.1 ppm, and the level of
radionuclide contamination should be less than units mBq/kg. At the NSC KIPT, the technologies have been
developed for the production of high-purity refractory (W, Mo, Re, Ru, Os) and low-melting metals (Zn, Cd, Te,
archPb), including isotopically-enriched ¹⁰⁶Cd, ¹¹⁶Cd, satisfying these requirements. Using these metals both as
individual elements and as part of low-background scintillation single crystals, it was possible to obtain a number of
new fundamental results in the field of astrophysics, together with the Institute for Nuclear Research of the National
Academy of Sciences of Ukraine and the Gran Sasso Laboratory of the National Institute of Physics (Italy).
Розглянуто особливості застосування високочистих речовин для дослідження рідкісних ядерних подій в
астрофізиці, зокрема подвійного β-розпаду. Відзначено, що для проведення подібних досліджень необхідні
спеціальні підземні лабораторії для усунення фону космічних випромінювань і застосування високочистих
матеріалів для можливості реєстрації рідкісних ядерних подій. Вміст нейтральних домішкових елементів
при цьому не повинен перевищувати 0,1 ррm, а рівень радіонуклідного забруднення – менше одиниць
мБк/кг. У ННЦ ХФТІ були розроблені технології отримання високочистих тугоплавких (W, Mo, Re, Ru, Os) і
легкоплавких (Zn, Cd, Тe, apxPb) металів, у тому числі ізотопно-збагачених ¹⁰⁶Cd, ¹¹⁶Cd, що задовольняють цим вимогам. З використанням цих металів як у вигляді окремих елементів, так і в складі низькофонових
сцинтиляційних монокристалів спільно з Інститутом ядерних досліджень НАН України та лабораторією
Гран-Сассо Національного інституту фізики (Італія) вдалося отримати ряд нових принципових результатів у
галузі астрофізики
Рассмотрены особенности применения высокочистых веществ для исследования редких ядерных
событий в астрофизике, в частности двойного β-распада. Отмечено, что для проведения подобных
исследований необходимы специальные подземные лаборатории для устранения фона космических
излучений и применение высокочистых материалов для возможности регистрации редких ядерных событий.
Содержание нейтральных примесных элементов при этом не должно превышать 0,1 ррm, а уровень
радионуклидного загрязнения – менее единиц мБк/кг. В ННЦ ХФТИ были разработаны технологии
получения высокочистых тугоплавких (W, Mo, Re, Ru, Os) и легкоплавких (Zn, Cd, Те, apxPb) металлов, в том
числе изотопно-обогащенных
¹⁰⁶Cd, ¹¹⁶Cd, удовлетворяющих этим требованиям. С использованием этих
металлов как в виде отдельных элементов, так и в составе низкофоновых сцинтилляционных
монокристаллов совместно с Институтом ядерных исследований НАН Украины и лабораторией Гран-Сассо
Национального института физики (Италия) удалось получить ряд новых принципиальных результатов в
области астрофизики.
|
| issn |
1562-6016 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/194338 |
| citation_txt |
High pure substances for astrophysical research / G.P. Kovtun // Problems of Atomic Science and Technology. — 2020. — № 1. — С. 8-11. — Бібліогр.: 8 назв. — англ. |
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| fulltext |
ISSN 1562-6016. PASТ. 2020. №1(125), p. 8-11.
HIGH PURE SUBSTANCES FOR ASTROPHYSICAL RESEARCH
G.P. Kovtun
1,2
1
National Science Center “Kharkov Institute of Physics and Technology”,
Kharkiv, Ukraine;
2
V.N. Karazin Kharkiv National University, Kharkiv, Ukraine
E-mail: gkovtun@kipt.kharkov.ua
The features of the application of high-purity substances for studying rare nuclear events in astrophysics, in
particular double beta decay, are considered. It was noted that for such studies, the special underground laboratories
are needed to eliminate the cosmic radiation background, and the use of high-purity materials for possibility to
record rare nuclear events. The content of neutral impurity elements should not exceed 0.1 ppm, and the level of
radionuclide contamination should be less than units mBq/kg. At the NSC KIPT, the technologies have been
developed for the production of high-purity refractory (W, Mo, Re, Ru, Os) and low-melting metals (Zn, Cd, Te,
arch
Pb), including isotopically-enriched
106
Cd,
116
Cd, satisfying these requirements. Using these metals both as
individual elements and as part of low-background scintillation single crystals, it was possible to obtain a number of
new fundamental results in the field of astrophysics, together with the Institute for Nuclear Research of the National
Academy of Sciences of Ukraine and the Gran Sasso Laboratory of the National Institute of Physics (Italy).
PACS: 23.40.-s; 29.40.Mc; 81.20.Ym
It is widely known the use of high-purity substances,
including metals, in various fields of engineering. First
of all, it is nuclear power engineering, electronics, fiber
optics. Recently, high-purity metals find an application
for microelectronics, medicine and other areas. The
main motivating stimulus in this direction is the need to
create materials with new physical and mechanical
properties. At the same time, very often the motivation
for production of high-purity substances is the striving
for basic research. Recently, investigations in the range
of astrophysics, i.e. in the field of studying elementary
particles of cosmological origin in order to expand our
conceptions about the World around us have been
developing. The “ordinary” material world actually
observed at the present time is about 4% of the actual
material world of the Universe. The rest of the material
world of the Universe is attributed to the so-called dark
energy (74%), dark matter (22%), about the nature of
which there are very vague ideas. The main efforts are
aimed at explaining the composition of the Universe, in
particular, the nature of dark matter, dark energy; study
of the properties of neutrinos and its importance in the
development of the Universe; investigation of cosmic
radiation; the searches for gravitational waves and
various effects outside the standard model of elementary
particles.
Dark matter in astronomy and cosmology is a form
of matter that does not emit electromagnetic radiation
and does not interact with it. This property of this form
of matter makes it impossible to observe it directly. It is
assumed that it consists of new particles that have not
yet been discovered under terrestrial conditions, which
are 1001000 times heavier than the proton, and that
their interaction with ordinary matter is comparable in
intensity with the interaction of neutrinos [1]. The
matter of the nature of dark energy is even more
obscure. Dark energy in cosmology is a type of energy,
introduced into the mathematical model of the Universe
in order to explain its observed accelerating expansion.
The nature of dark energy is the main mystery of
fundamental physics of the 21st century.
To explain the composition of the Universe, it is
extremely important to study the properties of the
neutrino and its importance in the development of the
Universe. The properties of neutrinos play an important
part in ascertaining the most interesting mysteries of the
Universe - the nature of dark matter (neutrino is the only
identified component of this mysterious substance) and
baryonic asymmetry [2, 3]. To present time, there is
convincing evidences of neutrino oscillations, which
indicate the presence of nonzero masses in neutrinos.
However, oscillation experiments are not able to
determine the magnitude of the neutrino mass. The most
sensitive and direct way to study the nature of a certain
type of neutrino (Majorana or Dirac) is to search for
neutrinoless double β-decay (0ν2β-decay) [1-4].
Double β-decay is the general name of several types
of radioactive decay of an atomic nucleus, as a result of
which the nuclear charge changes (increases, decreases)
by two units
(A, Z) (A, Z+2) + 2e
-
+ 2νe.
This is the rarest radioactive decay of all decays. All
11 nuclides for which this process was reliably observed
have a half-life within the range of 10
18
10
24
years,
which is by several orders of magnitude longer than the
lifetime of the Universe. There are two types of 2β
decay:
– two-neutrino 2β decay (2ν2β) in which two
neutrinos are emitted in the final state (found in 11
elements);
– neutrinoless 2β-decay (0ν2β) in which neutrino is
not emitted (not detected).
The detection of at least one example of a
neutrinoless mode (0ν2β decay) will mean a revision of
the provisions of the standard model. However, to date,
only lower limitations on the half-lives of 0ν2β decay,
which reach 10
25
years, have been obtained. It
corresponds to the upper limitation on the Majorana
neutrino mass of about 0.4 eV.
The main difficulty encountered in carrying out the
experiments on the study of 2β decay is caused by the
low probability of the event, the need for long-term
experiments and maximum reduction in background
events as well as for a thorough analysis of the results.
The search for double β decay is one of the priority
tasks of modern physics. It is due to the fact that just
during the investigation of 2β decay one can obtain
information about the absolute mass scale and the
scheme of mass states of neutrino, check the law of
lepton charge conservation, find out the nature of the
neutrino (Dirac or Majorana particle) and a number of
other effects outside the standard model of elementary
particles.
Experiments on recording rare nuclear events (dark
matter particles, 2β decay, etc.) require at least two
conditions to be fulfilled: carrying out experiments deep
underground to reduce the radiation background of
cosmic rays, and producing high-purity substances to
create low-background high-sensitivity detectors and
protective materials shielding against residual radiation
exposure of the environment. To achieve good
scintillation properties of the detector, the content of
many impurity elements must be ˂ 0.1 ppm. Even more
stringent requirements are imposed on the radioactive
purity of the detector. The content of a number of
natural radionuclides should be ˂ 0.10.01 ppb, and
that of the uranium-thorium chain should be
˂ 1.00.1 ppt.
More than 20 underground laboratories, located at
depths from hundreds of meters to 2 km, have been
formed in the world to carry out experiments
underground. One of the largest is the Gran Sasso
National Laboratory, one of the four laboratories of the
Italian National Institute of Nuclear Physics. The
laboratory consists of a ground part and underground
premises located at an average depth of about 1400 m
(3600 m of water equivalent) and at an altitude of about
1000 m above sea level.
The underground part of the laboratory consists of
three large halls connected by underground tunnels.
Each hall has a length of 100 m, a width and a height of
about 20 m. Access to the underground halls of the
laboratory is through a car tunnel with a long of more
than 10 km. The underground arrangement allows
reducing the background of cosmic radiation by many
orders of magnitude.
Research in the Gran Sasso laboratory is carried out
in two main areas:
– study of the properties and interactions of
neutrinos, which includes the search for 2β decay;
– search for the particles of which dark matter could
consist.
Three large detectors are currently registering
neutrinos: Borexino, LVD, OPERA. These are complex,
massive buildings made of very pure materials,
measured in hundreds and thousands of tons, with liquid
scintillators for detecting neutrino flares and other rare
nuclear events. In the OPERA experiment, neutrinos are
detecting, the beam of which is directed to Gran
Sassofrom CERN (Switzerland). A neutrino beam
travels 730 km inside the Earth before it reaches the
detector.
The detection of such “elusive” particles as
neutrinos is complicated by natural radioactivity which
always present to some extent in any materials and
imitating the processes of neutrino interaction. The
degree of purity of the materials used in the detectors is
amazing. So, as a result of long-term development of
technologies for removal of natural radioactive
impurities from liquids and gases, the fantastic results
were achieved: in every gram of the substance with
which the neutrino interacts, only 10
-17
g (10
-15
%) of
extraneous impurities are contained. For example, the
nitrogen used in the experiments has a radioactivity by
billion times less than that of natural nitrogen. A similar
level of radionuclide contamination is also characteristic
of other materials of the detector. There is no doubt that
the developed new technologies will have a huge impact
on the pharmaceutical industry, the nanomaterials
industry and the technology for the production of new-
generation electronic components.
Recently, solid-state scintillation detectors have
been used as detectors for recording rare nuclear events.
The scintillation method is promising that for the study
of 2β decay owing to the availability of scintillators
containing elements that have potential 2β-active
isotopes. In addition, it is possible to investigate several
nuclei simultaneously, identify α and β particles, and
ensure stability of operation for long periods (years).
The most promising by luminescent and scintillation
properties as the detectors for recording rare nuclear
events are the following scintillation materials: (Cd,
106
Cd,
116
Cd)WO4, (Zn,
64
Zn,
70
Zn)WO4, PbWO4, (Cd,
106
Cd,
116
Cd)МоO4, (Zn,
64
Zn)МоO4, PbMoO4, MgWO4,
CaF2, MgF2, ZnSe etc. In order to get crystals with high
scintillation characteristics, it is necessary to implement
the control of the purity of the initial materials and the
mixture at the level of ˂0.1 ррm for a number of
impurities. To ensure radionuclide purity, it is necessary
to control radioactive impurities at the level of µBq/kg
(
228
Th and
226
Ra) and units of mBq/kg (α-active
elements U/Th).
The production of scintillators made of enriched
isotopes can significantly increase the sensitivity of
experiments for the search for double β-decay.
The sensitivity of solid-state scintillators increases
significantly when they contain isotopically enriched
elements capable to be subjected to 2β decay. The
sensitivity of determining the half-life of 2β decay is
directly proportional to the isotopic content relative to
the parent nuclide.
Therefore, the enrichment of the investigated
material with the necessary isotope by an order of
magnitude leads to a proportional increase in the
sensitivity of the experiment. For example, natural
cadmium consists of eight stable isotopes:
106
Cd (1.22%),
108
Cd (0.88%),
110
Cd (12.39%),
111
Cd (12.75%),
112
Cd (24.07%),
113
Cd (12.26%),
114
Cd (28.85%), and
116
Cd (7.58%). The nuclei of two
isotopes of this set –
106
Cd and
116
Cd undergo by double
beta decay, in connection with that the special interest is
caused precisely in these isotopes.
NSC KIPT has developed complex methods for the
production of a number of high-purity refractory (W,
Mo, Re, Ru, Os) and low-melting metals (Zn, Cd, Te,
arch
Pb), including isotopically enriched
106
Cd (65%),
116
Cd (81%), for investigations of 2β decay [5, 6]. The
use of high-purity metals made it possible to produce (at
the Institute of Scintillation Single Crystals of NASU,
Institute of Inorganic Chemistry, Novosibirsk, Russia) a
number of scintillation single crystals of unprecedented
high quality (ZnWO4, CdWO4,
106
CdWO4,
116
CdWO4,
PbWO4,
arch
PbWO4, PbMoO4Zn
82
Se etc.), on the basis
of which the low-background scintillation detectors
were created to record various rare nuclear events.
As a result of recent experiments using high purity
Zn,
116
Cd,
106
Cd,
arch
Pb, W, Ru, Os both in the form of
individual elements and as a part of low-background
scintillation single crystals, together with the Institute
for Nuclear Research of the NAS of Ukraine and the
Grant Sasso Laboratory of the National Institute of
Physics (Italy), a number of new fundamental results
were obtained:
– 2β decay in Zn,
116
Cd,
arch
Pb, W, Ru, Os was
studied at the new level of sensitivity;
– restrictions on the neutrino mass are established at
the level of 0.30.7 eV;
– neutrino flux was first measured as a result of the
decay of
7
Be nuclei under the influence of sunlight;
– antineutrinos emitted from the depths of the Earth
were recorded;
– studies of rare α-, β-decays of atomic nuclei were
performed.
Recently, the first stage of the search for
neutrinoless 2β-decay occurring on Zn
82
Se crystals has
been performed. A zinc selenide crystal was produced at
the Institute of Scintillation Single Crystals of NASU,
and high-purity zinc did at the NSC KIPT.
Investigations had been performed using a cryogenic
bolometric technique [7]. The cryogenic bolometer
consisted of an absorbing material cooled to a very low
temperature (about 1020 mK) and a thermometer
capable of measuring the temperature increase at a very
low energy of recoil of interacting particles to the
absorber. If the absorbing material is also a scintillator,
then this makes it possible to distinguish interacting
particles of various types by changing the ratio of light
to heat. Thin plates of the high-purity germanium
isotope
76
Ge were used as bolometric light detectors.
The preliminary experiments made it possible to fix the
inferior limitations on the half-life of the 0ν2β decay of
82
Se, which is > 3.5∙10
24
years [8].
The scientific goal of these studies was not only to
search for 2β decay, but also to lay the foundation for
the next generation experiment which fully utilizes the
innovative potential of this new method.
CONCLUSIONS
Recently, the investigations have been intensively
developing in the area of particle astrophysics in order
to expand our conceptions about the World around us.
Development of the particle astrophysics requires the
elaboration of scintillation materials having low degree
of radioactive contamination, containing certain
elements, as well as possessing parameters which are at
the limit of possibilities of modern technologies.
Scintillators made of enriched isotopes take a special
place, and allow significantly increase the sensitivity of
experiments aimed at searching for 2β decay. Despite
the large material costs, new underground laboratories
are being created in many countries and new detectors
are being developed to study the nature of neutrinos and
record rare nuclear events in astrophysics.
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Article received 18.11.2019
ВЫСОКОЧИСТЫЕ ВЕЩЕСТВА ДЛЯ АСТРОФИЗИЧЕСКИХ ИССЛЕДОВАНИЙ
Г.П. Ковтун
Рассмотрены особенности применения высокочистых веществ для исследования редких ядерных
событий в астрофизике, в частности двойного β-распада. Отмечено, что для проведения подобных
исследований необходимы специальные подземные лаборатории для устранения фона космических
излучений и применение высокочистых материалов для возможности регистрации редких ядерных событий.
Содержание нейтральных примесных элементов при этом не должно превышать 0,1 ррm, а уровень
радионуклидного загрязнения – менее единиц мБк/кг. В ННЦ ХФТИ были разработаны технологии
получения высокочистых тугоплавких (W, Mo, Re, Ru, Os) и легкоплавких (Zn, Cd, Те,
apx
Pb) металлов, в том
https://www.sciencedirect.com/science/journal/01689002
https://www.sciencedirect.com/science/journal/01689002
https://www.sciencedirect.com/science/journal/01689002
числе изотопно-обогащенных
106
Cd,
116
Cd, удовлетворяющих этим требованиям. С использованием этих
металлов как в виде отдельных элементов, так и в составе низкофоновых сцинтилляционных
монокристаллов совместно с Институтом ядерных исследований НАН Украины и лабораторией Гран-Сассо
Национального института физики (Италия) удалось получить ряд новых принципиальных результатов в
области астрофизики.
ВИСОКОЧИСТІ РЕЧОВИНИ ДЛЯ АСТРОФІЗИЧНИХ ДОСЛІДЖЕНЬ
Г.П. Ковтун
Розглянуто особливості застосування високочистих речовин для дослідження рідкісних ядерних подій в
астрофізиці, зокрема подвійного β-розпаду. Відзначено, що для проведення подібних досліджень необхідні
спеціальні підземні лабораторії для усунення фону космічних випромінювань і застосування високочистих
матеріалів для можливості реєстрації рідкісних ядерних подій. Вміст нейтральних домішкових елементів
при цьому не повинен перевищувати 0,1 ррm, а рівень радіонуклідного забруднення – менше одиниць
мБк/кг. У ННЦ ХФТІ були розроблені технології отримання високочистих тугоплавких (W, Mo, Re, Ru, Os) і
легкоплавких (Zn, Cd, Тe,
apx
Pb) металів, у тому числі ізотопно-збагачених
106
Cd,
116
Cd, що задовольняють
цим вимогам. З використанням цих металів як у вигляді окремих елементів, так і в складі низькофонових
сцинтиляційних монокристалів спільно з Інститутом ядерних досліджень НАН України та лабораторією
Гран-Сассо Національного інституту фізики (Італія) вдалося отримати ряд нових принципових результатів у
галузі астрофізики.
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