Angular correlation α-particles in the reaction ¹²С(γ, 3α) at the formation of ⁸Be nucleus in the first excited state
Investigation of channel formation of the first excited state of ⁸Be nucleus in ¹²С(γ, 3α) reactions is executed. The methodic of kinematical models of γ + ¹²С → α₁ + ⁸Be* reaction is developed and is correctly selected α₁-particle. The angular distributions of γ + ¹²С → α₁ + ⁸Be* reaction and chann...
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| Zitieren: | Angular correlation α-particles in the reaction ¹²С(γ, 3α) at the formation of ⁸Be nucleus in the first excited state / S.N. Afanas’ev // Вопросы атомной науки и техники. — 2011. — № 3. — С. 22-26. — Бібліогр.: 12 назв. — англ. |
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| author | Afanas’ev, S.N. |
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| citation_txt | Angular correlation α-particles in the reaction ¹²С(γ, 3α) at the formation of ⁸Be nucleus in the first excited state / S.N. Afanas’ev // Вопросы атомной науки и техники. — 2011. — № 3. — С. 22-26. — Бібліогр.: 12 назв. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| description | Investigation of channel formation of the first excited state of ⁸Be nucleus in ¹²С(γ, 3α) reactions is executed. The methodic of kinematical models of γ + ¹²С → α₁ + ⁸Be* reaction is developed and is correctly selected α₁-particle. The angular distributions of γ + ¹²С → α₁ + ⁸Be* reaction and channel of disintegration of nucleus ⁸Be* → α₂ + α₃ are measured. The elements of density matrix of ⁸Be* nucleus and spherical spin-tensors characterizing polarization of ⁸Be* nucleus definite.
Виконано дослідження каналу утворення першого збудженого стану ядра ⁸Be в реакції ¹²С(γ, 3α). Розроблено методику кінематичного моделювання реакції γ + ¹²С → α₁ + ⁸Be* і коректно виділена α₁-частинка. Виміряно кутові розподіли реакції γ + ¹²С → α₁ + ⁸Be* і каналу розпаду ядра ⁸Be* → a₂ + a₃. Вперше визначено елементи матриці густини ядра ⁸Be* і сферичні спін-тензори, що характеризують поляризацію ядра ⁸Be*.
Выполнено исследование канала образования первого возбужденного состояния ядра ⁸Be в реакции ¹²С(γ, 3α). Разработана методика кинематического моделирования реакции γ + ¹²С → α₁ + ⁸Be* и корректно выделена α₁-частица. Измерены угловые распределения реакции γ + ¹²С → α₁ + ⁸Be* и канала распада ядра ⁸Be* → α₂ + α₃. Впервые определены элементы матрицы плотности ядра ⁸Be* и сферические спин-тензоры, характеризующие поляризацию ядра ⁸Be*.
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ANGULAR CORRELATION α-PARTICLES IN THE
REACTION 12C(γ, 3α) AT THE FORMATION OF 8Be
NUCLEUS IN THE FIRST EXCITED STATE
S.N. Afanas’ev∗
National Science Center ”Kharkov Institute of Physics and Technology”, 61108, Kharkov, Ukraine
(Received April 11, 2011)
Investigation of channel formation of the first excited state of 8Be nucleus in 12C(γ, 3α) reactions is executed. The
methodic of kinematical models of γ +12 C → α1 +8 Be∗ reaction is developed and is correctly selected α1-particle.
The angular distributions of γ +12 C → α1 +8 Be∗ reaction and channel of disintegration of nucleus 8Be∗ → α2 + α3
are measured. The elements of density matrix of 8Be∗ nucleus and spherical spin-tensors characterizing polarization
of 8Be∗ nucleus definite.
PACS: 25.20.-x
1. INTRODUCTION
At present studies of the systems with the selected
orientation of spin is given in nucleus physicist big
attention [1]. Along with extremely difficult experi-
ments with use of the polarized beams and targets the
method of reception of the information on properties
of the oriented systems, based on studying of func-
tions of correlation of formation of the excited states
and their disintegration in three-particles reactions of
type A(γ, a)B∗(b, c) is developed. Amplitude of such
reaction of the consequent type is factorized on am-
plitude of reaction A(γ, a)B∗ and amplitude of decay
B∗ → b + c [2]. The characteristic of the particle B∗,
having nonzero spin and being in the excited states,
are rather sensitive to change of the mechanism of
reaction. The analysis of such parameters enables to
get additional information about nucleus structure,
nuclear interaction and nucleon associations.
Earlier [3] was us it is shown, that disintegration
of nucleus of carbon on α-particles goes as consequent
process with formation of nucleus on intermediate
stage: γ +12 C → α1 +8 Be∗ (I) and 8Be∗ → α2 + α3
(II). In this report the analysis of events in area of
the first maximum of total cross sections 12C(γ, 3α)
reactions will be executed - at photon energies of
up to 22 MeV. Here possible channel of the forma-
tion of 8Be nucleus in the ground state and first ex-
cited states. The partial channel of the formation the
ground state of 8Be nucleus is reliably selected [4],
therefore is not a background for remaining events.
The use in the experiment 4π-detector (a diffu-
sion chamber [5] placed in a magnetic field) enables
to measure the angular distributions in the systems
(I) and (II), and define amplitudes of the formation
and disintegration of 8Be nucleus. The matrix ele-
ments of amplitudes can be expressed through the el-
ements normalized of the density matrix ρik [6, 7] and
depends only from polarization t00,IM even rank. De-
termination of the density matrix gives unique possi-
bility to define the polarization tensor of 8Be nucleus
[2], which includes information not only about the
spin state of this nucleus, but also about all nuclear
reaction on the whole. Angular distributions in in
the system (I) the first element of spin-tensor of the
density matrix ρ00 is presented only. Different from
ρ00 elements spin-tensor of the density matrix of 8Be
nucleus (determined by the angular distributions of
the system (II)) are not simply additional parame-
ters, but descriptions determining the mechanism of
reaction 12C(γ, 3α).
2. DETERMINATION α1-PARTICLES,
ACCOMPANYING FORMATION OF 8Be
NUCLEUS
The energy of the relative motion (Ex) of two α-
particles is [6]
Ex =
(−→p i −−→p k)2
4m
, (1)
where i, k are their numbers and p and m are their
3-momentum and mass, respectively. Because of par-
ticle identity, we were unable to select a pair produced
upon 8Be in constructing Ex distributions, we there-
fore used three values of Ex to represent each event.
In Fig.1,a, the distributions are shown by light points.
The histogram step by 0.25 MeV, and the points were
placed in the middle of intervals. The displayed er-
rors are purely statistical.
Distribution is compared to the phase [6]:
f(Ex) =
√
Ex ·
√
Emax
x − Ex , (2)
∗Corresponding author E-mail address: afanserg@kipt.kharkov.ua
22 PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY, 2011, N3.
Series: Nuclear Physics Investigations (55), p.22-26.
where Emax
x - maximum kinetic energy in the sys-
tem of two α-particles, equal to total energy all
particles in s.c.m. For a continuous photon spec-
trum, phase distributions were calculated step by
step. First, this was done for photon-energy in-
tervals 1 MeV wide. The area under the curve
was normalized to the number of events per inter-
val. After that, summation of probabilities was per-
formed for identical intervals of energies Ex. In
Fig.1,a phase distributing it is shown a solid curve.
Fig.1. Excitation energy distribution for the
system of two α-particles
The experimental distributions of pairs α-
particles differs from a phase and has two maxima,
that whose parameters are E1
0 = 3.12 ± 0.04 MeV
and Γ1 = 1.89±0.07 MeV and that whose parameters
are E2
0 = 8.13±0.12 MeV and Γ2 = 4.17± 0.24 MeV.
The parameters of the first maximum are near to sim-
ilar means of the first excited state of 8Be nucleus
(E0 = 3.04 MeV and Γ = 1.5 MeV from the known
compiling of spectroscopic data [8]).
For the analysis of distributions in Fig.1,a the
method of mathematical model 12C(γ, 3α) reactions
was developed. On the basis of this model, one
can deduce the distribution of energies of the rela-
tive motion of two α-particles, employing parameters
of known levels of the 8Be nucleus, a specific form
of angular distributions in the rest frame of two α-
particles, and the experimental energy dependence of
the total cross section. The form of angular distribu-
tions in the reference frame commotion with the cen-
ter of mass α1 +8 Be∗ system has no effect on the Ex
distribution since it characterizes the rotation of the
system as a discrete unit. The angular distribution of
α-particles in the rest frame of the 8Be nucleus play
a significant role in the Ex distribution. We chose the
form of the angular distribution as follows: the exper-
imental angular distribution in the system of rest of
the Ex nucleus were obtain, energy of excitation the
8Be nucleus is near to the first level [8] and executed
approximation by trigonometric functions. A polar
angle was counted off from direction of motion of the
8Be nucleus and took into account the measurement
errors in the particle momenta is 4 MeV/c and in the
polar angle is 2◦ [3]. As in a model there is possibility
simply to identify α-particles, two types of distribut-
ing on energy of excitation of pair α-particles were
obtain - resonance function of excitation of the 8Be
nucleus (α2α3) (in the Fig.1,b solid curve) and back-
ground distributing (on the Fig.1,b dashed curve),
where one of particles α1(α1α2 and α1α3).
The result obtained on the basis of this model
(sum of the resonance and background distributing)
for the channel of formation of the 8Be nucleus in
the first excited state is shown in the Fig.1,a dashed
curve. The agreement of model with the experiment
allows to equate the first resonance with the first ex-
cited state of the 8Be nucleus, and second to consider
a background. From Fig.1,b follows that resonance
and background distribution has a zone of the over-
lapping that in the experiment complicates the se-
lection α-particles, giving contribution to resonance.
With the purpose of search of terms for the reliable
division of distributing was executed the following:
a) intervals on energy γ-quantum Eγ were varied,
that causes change of background part;
b) restraints on energy of excitation of resonance
pair α-particles Ex were imposed (diminishes a zone
of the overlapping).
It is definite, that at Eγ = 16...20 MeV and
Ex(α2α3) ≤ 3.04 MeV the resonance and back-
ground pairs α-particles were reliably divided and,
consequently, was exactly determined α1. In the
Fig.1,c the results of model at optimum conditions
are presented.
To make sure, that by such limitations the struc-
ture of the angular distributing was not changed in
the systems of rest (I) and (II), verification of influ-
encing of choice of conditions of separation of reso-
nance and background parts on the proper angular
distributing was executed. By means of modeling
the angular distributing in different systems of rest
in two variants were built: with limitation for Eγ
and Ex and without. It is definite, that limitations
on Eγ and Ex do not change type of the angular dis-
tributing.
3. ANGULAR DISTRIBUTIONS
Reliable selection in the experiment α1-particles
at formation of first excited the states of 8Be nucleus
allows correctly to build the angular distributing in
the systems (I) and (II).
For the unpolarized beam the differential section
of the investigated reaction of successive type can be
written down as product of cross section of formation
of 8Be nucleus in the system of center of reaction (I)
23
and correlation function of the disintegration of 8Be
nucleus (II) W (α, β) [2]:
d2σ
dθdΩα,β
∼ dσ
dθ
·W (α, β) , (3)
where θ - the angle of output of 8Be nucleus in the
system (I) (axis of quantum - along direction motion
of photons); α - polar, β - azimuthal angles in the sys-
tem (II) (axis of quantum - along direction of motion
8Be nucleus).
3.1. REACTION OF FORMATION OF 8Be
NUCLEUS
Differential sections of dσ/dθ it was deter-
mined in the system of rest (α1 +8 Be) (I).
Results are presented by light points in the
Fig.2,a. Distributions are symmetric in relation 90◦.
Fig.2. Angular distributions: a) - γ +12 C →
α1 +8 Be∗, ◦ - our experiment, • - [10], solid curve -
fitting of Legendre polynomials, dashed curve - [11];
b), c)– system of 8Be∗ → α2 +α3 (• - polar angle α,
◦ - azimuthal angle β, our experiment), solid curves
and dashed curve - fitting corresponding angles
To the solid curve on the fig.2a fitting of our ex-
perimental data on MNK is shown by factorization
[9]:
dσ
dθ
=
4∑
i=0
ciPi(θ) , (4)
where Pi(θ) - the Legendre polynomials, ci - coeffi-
cients at polynomials.
Results of fitting: c0=14.05±0.91, c1=1.33±1.35,
c2=1.59±1.77, c3=-0.37±1.85, c4=-9.42±2.11,
χ2/DoF = 0.64. In the parameters of c1, c2 and
c3 means and error of their measuring are near.
In work [9] multipole amplitudes of the reaction
photodisintegration Jπ + 0+ → Jπ(12C) → 2+ + 0+
with formation of the compound of 12C nucleus are
definite. The finish state corresponds to the explored
in our work channel (8Be + α1). Calculations are
executed for the spins of 12C nucleus Jπ = 1−, 1+
and 2+. The coefficient of c4 arises up only at clean
E2-transition with the high values of the orbital mo-
ment L. Quantitative correlations of coefficients in
our experiments can correspond to multipoles with
LJS=222 and LJS=422, where J - total moment, S -
spin of the finish system. At the same time, in the
known tables of spectroscopy data [11], there are no
levels of 12C nucleus with Jπ(12C) = 2+ and isotop-
spin T=0, able to realize this process.
By dark points in the Fig.2,a experimental re-
sults [10] are presented. The analysis of the angu-
lar distributing in this work showed that the mix-
ture E1- and E2-transitions with a considerable role
from E2-transitions is prevailing. The not strict se-
lection of channel of reaction is possible explanation
of such divergence with our data. By a pair α-
particles, formative of 8Be nucleus, those at which
energy of excitation is found near-by were considered
(2.95±0.09) MeV. And α-particles, accompanying to
formation of 8Be nucleus, was considered the first
out off. However, as visible (the Fig.1,b), it not for
certain divides the resonance and background distrib-
uting.
In theoretical work [12] contribution of coulomb
and nuclear interactions of products reactions on
the angular distributing of primary α-particles the
12C(γ, 3α) reaction with transition on the level of 2+
of 8Be nucleus within the framework of model of nu-
cleon associations is explored and their substantial
role is shown. Consideration of the final state in-
teraction (the dotted curve on the Fig.2,a) gives a
considerable isotropic constituent into calculation on
comparison with clean E1- and E2-transitions. Qual-
ity a curve explains the results of experiment. A con-
clusion is done, that the reaction can proceed without
formation of the compound 12C nucleus. However
calculation of angular distributions in the system of
rest of 8Be nucleus is absent.
3.2. DISINTEGRATION OF 8Be NUCLEUS
To get the angular distributing of products of
disintegration in the system of his rest of 8Be nu-
cleus (II), it must integrated expression (3) on dθ and
dΩα,β . The correlation function W (α,β) it is possible
to express through he elements normalized of the den-
sity matrix ρik [6, 7]. For the 2+ state of 8Be nucleus
and taking to account that spin α-particles equal to
zero here only one amplitude which relies only on po-
larization of t00,IM even ranks. Here zeros mean the
unpolarized initial state, I - complete moment of the
system and M - projection of complete moment. In
our experiment from insufficient statistical material
well-being it is necessary to execute integration on
the angles of output of particle α1. It lays on limita-
tion: M=0. Dependence of angular distributions in
24
the system of rest of 8Be nucleus is [6]:
W ∝
∑
MM ′
ei(M−M ′)βdM0(α)dM ′0(α)ρMM ′ , (5)
where M, M′ are projections of complete moment of
8Be nucleus. Matrix elements of the operator of turn
(d-functions) for the correspondent moments is taken
from tables [2, 6]. For expansion was used hermicity
of the density matrix ρMM ′ . Combining elements at
the identical values of exponent:
W ∝ p0+p1cosβ+p2cos2β+p3cos3β+p4cos4β , (6)
where
p0 =
(3cos2α− 1)2
2
ρ00 + 3sin2αcos2αρ11 +
3
4
sin4αρ22 ,
p1 =
3
2
(sin3αcosαReρ21 − sin2αcos2αReρ10) ,
p2 =
√
6
4
sin2α(3cos2α− 1)Reρ20 − 3
2
sin2αcos2αReρ1−1 ,
p3 = −3
2
sin2αcos2αReρ2−1 ,
p4 =
3
8
sin4αReρ2−2 . (7)
From insufficient poor statistic of experiment, ex-
pression (6) on azimuth (β) and polar (α) degrees
is integrated and dependencies are define accordingly
on α and β.
A) DISTRIBUTION ON A POLAR ANGLE
Distributing on a degree α is resulted in a Fig.2,b
closed circles. For the 2+ state of 8Be nucleus dif-
ferential sections after integration on an azimuth de-
gree (β) fitting (in the Fig.2,b solid curve) is exe-
cuted by the expression F (α) = a0(3cos2α − 1)2 +
a1sin
2αcos2α + a2sin
4. Parameters of the fitting
a0=0.215±0.017, a1=1.629±0.066, a2=0.642±0.067,
χ2/DoF=1.65 are used for determination of elements
of the density matrix ρ: a0 = 0.5πρ00, a1 = 0.5πρ11
and a2 = 1.5πρ22.
Their rate normalized is executed with the
use of expression sp(ρ) = 2ρ22 + 2ρ11 + ρ00=1.
As result of ρ00=0.124±0.001, ρ11=0.079±0.003,
ρ22=0.124±0.013. Density matrix of 8Be nucleus
factorized on spherical spin-tensor tIM , character-
izing polarization of 8Be nucleus: t00=1 - normal-
ization requirement, t20 = Sp(τ20ρ)=2.39ρ22-1.2ρ11-
1.2ρ00, t40 = Sp(τ40ρ)=0.53ρ22-2.14ρ11+1.6ρ00. Us-
ing the means of elements of the density matrix, we
will define statistical tensors: t20=0.053±0.021 and
t40=0.096±0.018. The angular distributing can be
factorized [2] on the Legendre polynomials, statisti-
cal tensors will be coefficients at which
W = A(1 + t20P2(cosα) + t40P4(cosα)) (8)
The results of fitting expression (8) on a Fig.2,b
dashed curve are shown. Parameters of fitting:
A=0.268±0.009, χ2/DoF=0.82.
B) DISTRIBUTION ON AN AZIMUTH
ANGLE
Distributing on a degree β is resulted in a Fig.2,c
open circles. For the 2+ state of 8Be nucleus differen-
tial sections after integration on an polar degree (α)
fitting (in the Fig.2,c solid curve) is executed by the
expression F (β) = b0 + b1cos2β + b2cos4β. Parame-
ters of the fitting b0=60.711±0.799, b1=0.071±1.131,
b2=-0.416±1.131 and χ2/DoF=1.77 are used for de-
termination of elements of the density matrix ρ:
b0 = 9ρ22 + 12ρ11 + 11ρ00, b1 = 2.45Reρ20 − 12ρ1−1
and b2 = 9ρ2−2. The parameters of b1 and b2 within
the limits of errors are near to the zero.
The complete section of disintegration of 8Be nu-
cleus after integrated on α and β expression (6):
σα,β ∼ 2π( π
32 )(9ρ22 + 12ρ11 + 11ρ00). The means
of the density matrix were definite before on distri-
butions of polar degree α and σα,β=2.111±0.163. It
is found in the consent with data [3], where partial
cross section of formation the first levels of 8Be nu-
cleus σ1=2.29±0.09.
4. CONCLUSIONS
In the γ +12 C → α1 +8 Be∗ reaction the chan-
nel of formation of 8Be nucleus in the first excited
state is investigated. The methodic of kinematical
models reactions is developed. It is definite the con-
dition for correct selection α1-particle, accompanying
formation of 8Be nucleus.
The angular distributions of γ +12 C → α1 +8 Be∗
reaction and channel of disintegration of nucleus
8Be∗ → α2 + α3 are measured.
In the system α1 +8 Be∗ the fitting by
the Legendre polynomials is executed and coeffi-
cients at polynomials are definite: c0=14.05±0.91,
c1=1.33±1.35, c2=1.59±1.77, c3=-0.37±1.85, c4=-
9.42±2.11, χ2/DoF=0.64. Within the framework of
model of formation of compound 12C∗ nucleus ex-
perimental data can be accounted for in clean E2-
transition with the high values of the orbital moment
L. However in the investigated region of energies there
are no levels of carbon with the proper quantum char-
acteristics.
In the system α2+α3 the dependence on polar (α)
and azimuth (β) angles is explored. The correlation
25
function W (α, β) it is possible to express through he
elements normalized of the density matrix ρik. The
angular distributions fitting by the functions F (α) =
a0(3cos2α−1)2 +a1sin
2αcos2α+a2sin
4 and F (β) =
b0 + b1cos2β + b2cos4β was executed. The coeffi-
cients a0, a1, a2 (a0=0.215±0.017, a1= 1.629±0.066,
a2=0.642±0.067) and b0, b1, b2 (b0=60.711±0.799,
b1=0.071±1.131, b2=-0.416±1.131) are definite.
The elements of density matrix (ρ00=0.124±0.001,
ρ11=0.079±0.003, ρ22=0.124±0.013) and
spherical spin-tensors (t20=0.053±0.021 and
t40=0.096±0.018), characterizing polarization of 8Be
nucleus was calculated.
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УГЛОВАЯ КОРРЕЛЯЦИЯ α-ЧАСТИЦ В РЕАКЦИИ 12C(γ, 3α) ДЛЯ КАНАЛА
ОБРАЗОВАНИЯ ЯДРА 8Be В ПЕРВОМ ВОЗБУЖДЕННОМ СОСТОЯНИИ
С.Н. Афанасьев
Выполнено исследование канала образования первого возбужденного состояния ядра 8Be в реакции
12C(γ, 3α). Разработана методика кинематического моделирования реакции γ +12 C → α1 +8 Be∗ и
корректно выделена α1-частица. Измерены угловые распределения реакции γ +12 C → α1 +8 Be∗ и
канала распада ядра 8Be∗ → α2 + α3. Впервые определены элементы матрицы плотности ядра 8Be∗ и
сферические спин-тензоры, характеризующие поляризацию ядра 8Be∗.
КУТОВА КОРЕЛЯЦIЯ α-ЧАСТИНОК У РЕАКЦIЇ 12C(γ, 3α) ДЛЯ КАНАЛУ
УТВОРЕННЯ ЯДРА 8Be В ПЕРШОМУ ЗБУДЖЕНОМУ СТАНI
С.М. Афанасьєв
Виконано дослiдження каналу утворення першого збудженого стану ядра 8Be в реакцiї 12C(γ, 3α).
Розроблено методику кiнематичного моделювання реакцiї γ +12 C → α1 +8 Be∗ i коректно видiлена α1-
частинка. Вимiряно кутовi розподiли реакцiї γ+12C → α1+8Be∗ i каналу розпаду ядра 8Be∗ → α2+α3.
Вперше визначено елементи матрицi густини ядра 8Be∗ i сферичнi спiн-тензори, що характеризують
поляризацiю ядра 8Be∗.
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| id | nasplib_isofts_kiev_ua-123456789-111069 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-02T04:15:06Z |
| publishDate | 2011 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Afanas’ev, S.N. 2017-01-08T09:03:22Z 2017-01-08T09:03:22Z 2011 Angular correlation α-particles in the reaction ¹²С(γ, 3α) at the formation of ⁸Be nucleus in the first excited state / S.N. Afanas’ev // Вопросы атомной науки и техники. — 2011. — № 3. — С. 22-26. — Бібліогр.: 12 назв. — англ. 1562-6016 PACS: 25.20.-x https://nasplib.isofts.kiev.ua/handle/123456789/111069 Investigation of channel formation of the first excited state of ⁸Be nucleus in ¹²С(γ, 3α) reactions is executed. The methodic of kinematical models of γ + ¹²С → α₁ + ⁸Be* reaction is developed and is correctly selected α₁-particle. The angular distributions of γ + ¹²С → α₁ + ⁸Be* reaction and channel of disintegration of nucleus ⁸Be* → α₂ + α₃ are measured. The elements of density matrix of ⁸Be* nucleus and spherical spin-tensors characterizing polarization of ⁸Be* nucleus definite. Виконано дослідження каналу утворення першого збудженого стану ядра ⁸Be в реакції ¹²С(γ, 3α). Розроблено методику кінематичного моделювання реакції γ + ¹²С → α₁ + ⁸Be* і коректно виділена α₁-частинка. Виміряно кутові розподіли реакції γ + ¹²С → α₁ + ⁸Be* і каналу розпаду ядра ⁸Be* → a₂ + a₃. Вперше визначено елементи матриці густини ядра ⁸Be* і сферичні спін-тензори, що характеризують поляризацію ядра ⁸Be*. Выполнено исследование канала образования первого возбужденного состояния ядра ⁸Be в реакции ¹²С(γ, 3α). Разработана методика кинематического моделирования реакции γ + ¹²С → α₁ + ⁸Be* и корректно выделена α₁-частица. Измерены угловые распределения реакции γ + ¹²С → α₁ + ⁸Be* и канала распада ядра ⁸Be* → α₂ + α₃. Впервые определены элементы матрицы плотности ядра ⁸Be* и сферические спин-тензоры, характеризующие поляризацию ядра ⁸Be*. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Ядерная физика и элементарные частицы Angular correlation α-particles in the reaction ¹²С(γ, 3α) at the formation of ⁸Be nucleus in the first excited state Кутова кореляцiя α-частинок у реакцiї ¹²С(γ, 3α) для каналу утворення ядра ⁸Be в першому збудженому станi угловая корреляция α-частиц в реакции ¹²С(γ, 3α) для канала образования ядра ⁸Be в первом возбужденном состоянии Article published earlier |
| spellingShingle | Angular correlation α-particles in the reaction ¹²С(γ, 3α) at the formation of ⁸Be nucleus in the first excited state Afanas’ev, S.N. Ядерная физика и элементарные частицы |
| title | Angular correlation α-particles in the reaction ¹²С(γ, 3α) at the formation of ⁸Be nucleus in the first excited state |
| title_alt | Кутова кореляцiя α-частинок у реакцiї ¹²С(γ, 3α) для каналу утворення ядра ⁸Be в першому збудженому станi угловая корреляция α-частиц в реакции ¹²С(γ, 3α) для канала образования ядра ⁸Be в первом возбужденном состоянии |
| title_full | Angular correlation α-particles in the reaction ¹²С(γ, 3α) at the formation of ⁸Be nucleus in the first excited state |
| title_fullStr | Angular correlation α-particles in the reaction ¹²С(γ, 3α) at the formation of ⁸Be nucleus in the first excited state |
| title_full_unstemmed | Angular correlation α-particles in the reaction ¹²С(γ, 3α) at the formation of ⁸Be nucleus in the first excited state |
| title_short | Angular correlation α-particles in the reaction ¹²С(γ, 3α) at the formation of ⁸Be nucleus in the first excited state |
| title_sort | angular correlation α-particles in the reaction ¹²с(γ, 3α) at the formation of ⁸be nucleus in the first excited state |
| topic | Ядерная физика и элементарные частицы |
| topic_facet | Ядерная физика и элементарные частицы |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/111069 |
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