M1 resonance in sd-shell nuclei
γ-Decay of a resonance-like structure observed in the reactions of radiative capture of protons by ²¹Ne, ²²Ne, ²⁵Mg, ²⁶Mg, ²⁹Si, ⁰³Si, ³³S, ³⁴S, and ³⁶S nuclei is studied. The M1 resonance built on the ground state of ²²Na, ²³Na, ²⁶Al, ²⁷Al, ³⁰P, ³¹P, ³⁵Cl, and ³⁷Cl is identified. The position of th...
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| Published in: | Вопросы атомной науки и техники |
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| Date: | 2003 |
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| Format: | Article |
| Language: | English |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2003
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| Cite this: | M1 resonance in sd-shell nuclei / A.S. Kachan // Вопросы атомной науки и техники. — 2003. — № 2. — С. 79-80. — Бібліогр.: 7 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1860170643538968576 |
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| author | Kachan, A.S. |
| author_facet | Kachan, A.S. |
| citation_txt | M1 resonance in sd-shell nuclei / A.S. Kachan // Вопросы атомной науки и техники. — 2003. — № 2. — С. 79-80. — Бібліогр.: 7 назв. — англ. |
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| container_title | Вопросы атомной науки и техники |
| description | γ-Decay of a resonance-like structure observed in the reactions of radiative capture of protons by ²¹Ne, ²²Ne, ²⁵Mg, ²⁶Mg, ²⁹Si, ⁰³Si, ³³S, ³⁴S, and ³⁶S nuclei is studied. The M1 resonance built on the ground state of ²²Na, ²³Na, ²⁶Al, ²⁷Al, ³⁰P, ³¹P, ³⁵Cl, and ³⁷Cl is identified. The position of the M1 resonance is explained taking into account pairing forces.
Вивчено гама-розпад резонансноподібных структур, які спостерігаються в реакціїї радіаційного захвату протонів ядрами ²¹Ne, ²²Ne, ²⁵Mg, ²⁶Mg, ²⁹Si, ⁰³Si, ³³S, ³⁴S і ³⁶S. Ідентифіковано М1-резонанс на основних станах ядер ²²Na, ²³Na, ²⁶Al, ²⁷Al, ³⁰P, ³¹P, ³⁵Cl і ³⁷Cl. Виявлено, що на положення центра ваги М1-резонансу впливає величина np-, nn-, pp-спарювання.
Изучен гамма-распад резонансноподобных структур, наблюдаемых в реакции радиационного захвата протонов ядрами ²¹Ne, ²²Ne, ²⁵Mg, ²⁶Mg, ²⁹Si, ⁰³Si, ³³S, ³⁴S, и ³⁶S. Идентифицирован М1-резонанс на основных состояниях ядер ²²Na, ²³Na, ²⁶Al, ²⁷Al, ³⁰P, ³¹P, ³⁵Cl, и ³⁷Cl. Обнаружено, что на положение центра тяжести М1-резонанса влияет величина np-, nn-, pp-спаривания.
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| first_indexed | 2025-12-07T17:58:49Z |
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M1 RESONANCE IN sd-SHELL NUCLEI
A.S. Kachan
National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
e-mail: kachan@kipt.kharkov.ua
γ-Decay of a resonance-like structure observed in the reactions of radiative capture of protons by 21Ne, 22Ne,
25Mg, 26Mg, 29Si, 30Si, 33S, 34S, and 36S nuclei is studied. The M1 resonance built on the ground state of 22Na, 23Na,
26Al, 27Al, 30P, 31P, 35Cl, and 37Cl is identified. The position of the M1 resonance is explained taking into account
pairing forces.
PACS: 25.40.Lw, 25.40.Ny, 27.30+i, 24.30.Cs, 23.20.-g
Having studied γ-decays of the resonance-like
structures observed in the reactions of radiative capture
of protons by 21Ne, 25Mg, 29Si and 33S nuclei, we iden-
tified for the first time the magnetic dipole resonance
(MDR) built on the ground states of the odd-odd 4N+np
22Na, 26Al and 30P nuclei and performed the search for
MDR in 34Cl nuclei [1,2]. The position of the center-of-
gravity (COG) of MDR (Ec.g=ΣkEkBk(M1)/ΣkBk(M1) ) in
these nuclei differs from that in 4N nuclei by 3 MeV
(Fig. 1) and , in fact, does not depend on mass number
A (it is usually thought that this dependence must be of
the form Ec.g=40⋅A-1/3).
Fig. 1. The positions of the COG of М1-resonance
for even nuclei of sd-shell. Open square and triangle
shows data from [7]
We explained the new fact by assuming the
existence of the triplet neutron-proton pairing. The joint
analysis of the MDR total strength and position in 4N,
4N+2n and 4N+np nuclei shows that the formation of
MDR in these nuclei is strongly influenced by the
valence nucleons and that the MDR COG is determined
not only by the energy of spin-orbit splitting but also by
the strengths of both the nn(pp)-pairing and the np-
pairing as well. The similar analysis for odd nuclei
shows that the position of MDR COG in these nuclei
depends on the state of odd particle: d5/2 or d3/2. The
position of MDR COG in the first case must be in the
region of excitation energies of 5…6 MeV because this
position is determined by the energy of spin-orbit
splitting only. In the second case, the nn- or pp-pairs
from d5/2-subshell can participate in the formation of
MDR and the position of MDR COG in odd nucleus
will then slightly differ from that position in
neighboring even nuclei with mass number (A−1), i.e.,
it will be situated in the region of excitation energies of
8…10 MeV.
Here γ-decays of the resonance-like structures
observed in 22Ne, 26Mg, 30Si, 34S, 36S(p,γ)23Na 27Al, 31P,
35Cl, 37Cl reactions are investigated in the region of
excitation energies of 9…11 MeV [3-6]. The
measurements of the excitation function of these
reactions are carried out in the region of energies of
accelerated protons Ep=1…3 MeV. These measurements
were held on the electrostatic accelerator of National
Scientific Center “Kharkov Institute of Physics and
Technology”. The spin and parity of the studied
resonances, the branching coefficients, the multipole
mixing coefficients and the probabilities of γ-transitions
are determined from the analysis of the decay schemes.
The analysis of the angular distributions involved
determining the spins of resonance states and the
multipole-mixing coefficients for γ-rays (δ) by
minimizing the quantity
( ) ( )
( )
⋅∑
−
=
n
2
n
nn02
θexpΔW
θexpWθtheorWA
χ (1)
where Wtheor(θ) = ΣkQkρk0Fk(J1,J2,L,δ)Pk is the theoretical
angular distribution of photons for the transition
between the initial and final states with spins J1 and J2,
Wexp(θ) and ∆Wexp(θ) are the experimental
PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2003, № 2.
Series: Nuclear Physics Investigations (41), p. 79-80. 79
E, MeV
Fig. 2. М1-resonance for odd nuclei of sd-shell
Fig. 3. The positions of the COG of М1-resonance
for odd nuclei of sd-shell. Open triangle shows data
from [7]
data and the corresponding statistical uncertainty, А0 is
the normalization constant, Qк is a coefficient
accounting finite dimensions of the detector, ρk0 is an
element of the statistical tensor, n is the number of
experimental points (angles). The fitting procedure for
odd nuclei differed from that for even nuclei: for odd
nuclei the parameters of the statistical tensor were
calculated and the multipole-mixing coefficient (δ)
remained the only fitting parameter. The spin values of
resonances at hand were defined, in general, via analysis
of transitions to the ground state. The parities were
defined based on the comparison of probabilities of
electromagnetic transitions of different multipolarity
with recommended upper limits of the given values [7].
The reduced probability of γ-transition B(M1) was
calculated using the expression
B(M1)↑=86,6⋅b⋅S(eV)/(2J+1)E3
γ, (2)
where b is the branching coefficient of γ-transition, J is
the spin of initial state, constant S is in eV, and Eγ is the
energy of γ-transition in MeV. All the studied
transitions are mainly the M1-transitions with the small
admixture of E2-multipolity.The obtained distributions
of the strengths of M1-transitions in 23Na [6], 27Al, 31P,
35Cl, 37Cl nuclei have resonance character (Fig. 2). The
positions of MDR COG in 23Na, 25Mg and 27Al are equal
to 5.6±0.2, 5.8±0.2 and 6.1±0.2 MeV respectively (Fig.
3) and are situated in the region of excitation energies
which is expected for nuclei with unclosed d5/2-subshell,
i.e. they are defined only by the energy of spin-orbit
splitting. The MDR COG built on the ground states of
31P, 35Cl, 37Cl nuclei are equal to 8.5±0.3, 9.1±0.1 and
10.5±0.2 MeV respectively and are situated in the
region of excitation energies expected for the odd nuclei
with closed d5/2-subshell. In other words the position of
MDR COG for these nuclei are affected by the
magnitude of nn(pp)-pairing in d5/2-subshell.
REFERENCES
1. A.S. Kachan, B.A. Nemashkalo,
V.E. Storizhko. Ml resonance in sd-shell nuclei //
Yad. Fiz. 1989, v. 49, №2, p. 367-370 (in Russian).
2. A.S. Kachan, A.N. Vodin, B.A. Nemashkalo,
R.P. Slabospitsky. On the position of M1-
resonance in odd-odd 34Cl nucleus // Yad. Fiz.
1992, v. 55, №10, p. 2609-2615 (in Russian).
3. A.S. Kachan, A.N. Vodin, V.M. Mishchenko,
R.P. Slabospitsky. Fine structure of M1 resonance
in 35Cl nucleus // Yad. Fiz. 1996, v. 59, p. 775-780
(in Russian).
4. A.S. Kachan, A.N. Vodin, V.M. Mishchenko,
R.P. Slabospitsky. Search and study of thin
structure of M1-resonance in 31P // Izvest. Akad.
Nauk (ser. fiz). 1998, v. 62, №1, p. 48-55 (in
Russian).
5. A.S. Kachan, A.N. Vodin, V.M. Mishchenko,
R.P. Slabospitsky. Search and study of thin
structure of M1-resonance in 27Al // Izvest. Akad.
Nauk (ser. fiz). 1999, v. 63, №5, p. 1032-1036 (in
Russian).
6. A.S. Kachan, A.N. Vodin, V.M. Mishchenko,
R.P. Slabospitsky. Search and study of thin
structure of M1-resonance in 23Na // Izvest. Akad.
Nauk (ser. fiz). 2000, v. 64, №5, p. 1046-1049 (in
Russian).
7. М. Endt. Energy levels of A=21-44 nuclei //
Nucl. Phys. 1990, v. A521, p. 349-354
80
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| id | nasplib_isofts_kiev_ua-123456789-110714 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-07T17:58:49Z |
| publishDate | 2003 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Kachan, A.S. 2017-01-06T08:55:51Z 2017-01-06T08:55:51Z 2003 M1 resonance in sd-shell nuclei / A.S. Kachan // Вопросы атомной науки и техники. — 2003. — № 2. — С. 79-80. — Бібліогр.: 7 назв. — англ. 1562-6016 PACS: 25.40.Lw, 25.40.Ny, 27.30+i, 24.30.Cs, 23.20.-g https://nasplib.isofts.kiev.ua/handle/123456789/110714 γ-Decay of a resonance-like structure observed in the reactions of radiative capture of protons by ²¹Ne, ²²Ne, ²⁵Mg, ²⁶Mg, ²⁹Si, ⁰³Si, ³³S, ³⁴S, and ³⁶S nuclei is studied. The M1 resonance built on the ground state of ²²Na, ²³Na, ²⁶Al, ²⁷Al, ³⁰P, ³¹P, ³⁵Cl, and ³⁷Cl is identified. The position of the M1 resonance is explained taking into account pairing forces. Вивчено гама-розпад резонансноподібных структур, які спостерігаються в реакціїї радіаційного захвату протонів ядрами ²¹Ne, ²²Ne, ²⁵Mg, ²⁶Mg, ²⁹Si, ⁰³Si, ³³S, ³⁴S і ³⁶S. Ідентифіковано М1-резонанс на основних станах ядер ²²Na, ²³Na, ²⁶Al, ²⁷Al, ³⁰P, ³¹P, ³⁵Cl і ³⁷Cl. Виявлено, що на положення центра ваги М1-резонансу впливає величина np-, nn-, pp-спарювання. Изучен гамма-распад резонансноподобных структур, наблюдаемых в реакции радиационного захвата протонов ядрами ²¹Ne, ²²Ne, ²⁵Mg, ²⁶Mg, ²⁹Si, ⁰³Si, ³³S, ³⁴S, и ³⁶S. Идентифицирован М1-резонанс на основных состояниях ядер ²²Na, ²³Na, ²⁶Al, ²⁷Al, ³⁰P, ³¹P, ³⁵Cl, и ³⁷Cl. Обнаружено, что на положение центра тяжести М1-резонанса влияет величина np-, nn-, pp-спаривания. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Nuclear reactions M1 resonance in sd-shell nuclei М1-резонанс в ядрах sd-оболонки М1-резонанс в ядрах sd-оболочки Article published earlier |
| spellingShingle | M1 resonance in sd-shell nuclei Kachan, A.S. Nuclear reactions |
| title | M1 resonance in sd-shell nuclei |
| title_alt | М1-резонанс в ядрах sd-оболонки М1-резонанс в ядрах sd-оболочки |
| title_full | M1 resonance in sd-shell nuclei |
| title_fullStr | M1 resonance in sd-shell nuclei |
| title_full_unstemmed | M1 resonance in sd-shell nuclei |
| title_short | M1 resonance in sd-shell nuclei |
| title_sort | m1 resonance in sd-shell nuclei |
| topic | Nuclear reactions |
| topic_facet | Nuclear reactions |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/110714 |
| work_keys_str_mv | AT kachanas m1resonanceinsdshellnuclei AT kachanas m1rezonansvâdrahsdobolonki AT kachanas m1rezonansvâdrahsdoboločki |