Analysis of the multipole transitions in the reaction ¹²C(γ,3α)
We obtained the relations for the amplitudes of the E1→⁵P₁, M1→⁵D₁, E2→⁵D₂-transitions at the two-cluster (α-⁸Ве(2⁺)) photodisintegration of the ¹²C nucleus from the analysis of the experimental data for ∑(90º)-asymmetry and the α-particle angular distributions in the reaction ¹²C(γ,α) at energies o...
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| Мова: | English |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2001
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| Назва видання: | Вопросы атомной науки и техники |
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| Цитувати: | Analysis of the multipole transitions in the reaction ¹²C(γ,3α) / V.N. Gur’ev // Вопросы атомной науки и техники. — 2001. — № 1. — С. 55. — Бібліогр.: 3 назв. — англ. |
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irk-123456789-784452015-03-18T03:01:53Z Analysis of the multipole transitions in the reaction ¹²C(γ,3α) Gur’ev, V.N. Nuclear reactions We obtained the relations for the amplitudes of the E1→⁵P₁, M1→⁵D₁, E2→⁵D₂-transitions at the two-cluster (α-⁸Ве(2⁺)) photodisintegration of the ¹²C nucleus from the analysis of the experimental data for ∑(90º)-asymmetry and the α-particle angular distributions in the reaction ¹²C(γ,α) at energies of the linearly polarized photons 15.8-33.5 МeV. 2001 Article Analysis of the multipole transitions in the reaction ¹²C(γ,3α) / V.N. Gur’ev // Вопросы атомной науки и техники. — 2001. — № 1. — С. 55. — Бібліогр.: 3 назв. — англ. 1562-6016 PACS:23.20.Js. http://dspace.nbuv.gov.ua/handle/123456789/78445 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Nuclear reactions Nuclear reactions |
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Nuclear reactions Nuclear reactions Gur’ev, V.N. Analysis of the multipole transitions in the reaction ¹²C(γ,3α) Вопросы атомной науки и техники |
| description |
We obtained the relations for the amplitudes of the E1→⁵P₁, M1→⁵D₁, E2→⁵D₂-transitions at the two-cluster (α-⁸Ве(2⁺)) photodisintegration of the ¹²C nucleus from the analysis of the experimental data for ∑(90º)-asymmetry and the α-particle angular distributions in the reaction ¹²C(γ,α) at energies of the linearly polarized photons 15.8-33.5 МeV. |
| format |
Article |
| author |
Gur’ev, V.N. |
| author_facet |
Gur’ev, V.N. |
| author_sort |
Gur’ev, V.N. |
| title |
Analysis of the multipole transitions in the reaction ¹²C(γ,3α) |
| title_short |
Analysis of the multipole transitions in the reaction ¹²C(γ,3α) |
| title_full |
Analysis of the multipole transitions in the reaction ¹²C(γ,3α) |
| title_fullStr |
Analysis of the multipole transitions in the reaction ¹²C(γ,3α) |
| title_full_unstemmed |
Analysis of the multipole transitions in the reaction ¹²C(γ,3α) |
| title_sort |
analysis of the multipole transitions in the reaction ¹²c(γ,3α) |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2001 |
| topic_facet |
Nuclear reactions |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/78445 |
| citation_txt |
Analysis of the multipole transitions in the reaction ¹²C(γ,3α) / V.N. Gur’ev // Вопросы атомной науки и техники. — 2001. — № 1. — С. 55. — Бібліогр.: 3 назв. — англ. |
| series |
Вопросы атомной науки и техники |
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AT gurevvn analysisofthemultipoletransitionsinthereaction12cg3a |
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2025-07-06T02:32:31Z |
| last_indexed |
2025-07-06T02:32:31Z |
| _version_ |
1836863091064700928 |
| fulltext |
ANALYSIS OF THE MULTIPOLE TRANSITIONS
IN THE REACTION 12C(γ,3α)
V.N. Gur’ev
National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
We obtained the relations for the amplitudes of the E1→5P1, M1→5D1, E2→5D2-transitions at the two-cluster (α-
8Ве(2+)) photodisintegration of the 12C nucleus from the analysis of the experimental data for Σ(90°)-asymmetry and
the α-particle angular distributions in the reaction 12C( γ ,3α) at energies of the linearly polarized photons 15.8-33.5
МeV.
PACS:23.20.Js.
Interest to the investigation of the 12C(γ,3α) reaction
is connected with the possibility of checking the α-clus-
ter model for the 12C nucleus and the two-particle mech-
anism of the photodisintegration with the production of
the 8Ве(2+) nucleus in the intermediate state [1]. The
problems are the interpretation of the structure in the en-
ergy dependence of the total cross-section of the reac-
tion in the photon energy region Eγ=10-38 MeV and the
mechanism of the increased emission of the primary α-
particles at an angle of 90° for some energy values imi-
tating the forbidden E1-transition with ∆T=0, where T is
the isospin. The possibility of estimating the relations of
the multipole contributions became possible due to the
publication of the experimental data about the angular
distributions [2] and the energy dependence of Σ(90°)-
asymmetry of the output of α-particles for the energies
of the linearly polarized photons 15.8-33.5 МeV [3].
To perform the analysis of the experimental data
[2,3] we have made the multipole expansion of Σ(90°)
for two-particle photodisintegration of the 12C nucleus
with the production of the 8Ве(2+) nucleus. In the ap-
proximation of the contribution of the E1→5P1, M1→
5D1 and E2→5D2-transitions we have obtained that Σ(90
°)=a/b, where
a=0.45E1
122 +2.25M1
222-2.69E2
222+
+2.83Re(M1
22E2*
22), (1)
b=3.15E1
122+2.25M1
222+4.47E2
222+
+2.83Re(M1
22E2*
22), (2)
EJ
LS and MJ
LS are the electric and magnetic multipole
amplitudes; J, L, S are, respectively, the total momen-
tum, the orbital momentum and the spin. In [2] using the
method of the lowest squares the angle distributions of
the primary α-particles was fit to the form of the series
dσ/dΩ= ∑
=
2
0n
Cncosnθ. (3)
In this approximation the interpretation of the experimen-
tal data was limited to the decomposition
dσ/dΩ= ∑
=
2
0n
Аn Рn(θ), (4)
where Рn(θ) is Legendre polynomial.
In the approximation (3)
С0=3.15E1
122+2.25M1
222+5.4E2
222+
+2.83Re(M1
22E2*
22), (5)
С1=-7Re(E1
12M1*
22)+6.2Re(E1
12E2*
22), (6)
С2=-0.45E1
122+2.25M1
222-1.2E2
222+
+8.85Re(M1
22E2*
22). (7)
In contrast to C1 in (3), it is possible to exclude from
Eq. (1), (2), (5), (7) the interferential term Re(M1
12E2*
22).
Taking into account the interpolation between the exper-
imental values for С20=С2/С0 [2] and for Σ(90°) [3] at Еγ
=15.8; 26; 28; 33.5 MeV we have obtained the follow-
ing relations
M1
222 =0.23E1
122+2.43E2
222, (8)
E2
222 =0.15E1
122+0.53M1
222, (9)
E2
222 =1.1E1
122+1.58M1
222, (10)
E2
222 =0.26E1
122+0.65M1
222, (11)
M1
222=0.70E1
122+4.85E2
222, (12)
M1
222=−0.74E1
122+0.51E2
222, (13)
for Еγ=15.8 MeV, Σ(90°)=0.26, С20=0; Еγ≈19-20 MeV, Σ
(90°)=0, С20=-0.2; Еγ=26 MeV, Σ(90°)=-0.36, С20=-0.4; Е
γ=27 MeV, Σ(90°)=0, С20=0; Еγ=33.5 MeV, Σ(90°)=0.75,
С20=1.8; Еγ=33.5 MeV, Σ(90°)=0.5, С20=1.8 respectively.
At Еγ=33.5 MeV, Σ(90°)<0.5, С20=1.8 a mathematical in-
correct expression for the multipole amplitudes arises.
Thus we have demonstrated the principle possibility
of getting in such an approach of the quantitative rela-
tions for the squares modulus of the amplitudes of the E1
→5P1, M1→5D1 and E2→5D2-transitions. From Eq. (9) -
(11) for 19<Еγ<27 MeV, where Σ(90°)<0, it follows that
E2→5D2-transition dominates. From Eq. (12) for 28<Еγ
<33.5 MeV the M1→5D1-transition dominates. For the
latter case this also follows from the form of the α-angu-
lar distribution dN/dΩ [2].
REFERENCES
1. R.I. Dzhibuti, V.I. Mamasakhlisov, T.S. Macha-
radze. Photonuclear reactions with α-particle emis-
sion and fourparticle correlations in light nuclei //
Yad. Fiz. 1965, v. 1, №6, p. 976-983 (in Russian).
2. R.A. Golubev, V.V. Kirichenko. A.S. Kostromin α-
particle angular distributions in the reactions
γ 12C→
3α and
γ 16O→4α // Yad. Fiz., 1997, v. 60, № 9,
p. 1572-1579 (in Russian).
3. V.V. Kirichenko. Research of the Σ-asymmetry in
reaction 12C(γ,3α) // Ukr. Fiz. Zhurn. 2000, v. 45,
№ 10, p. 1151-1153 (in Ukraine).
PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2001, № 1.
Series: Nuclear Physics Investigations (37), p. 55.
55
V.N. Gur’ev
National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
REFERENCES
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