Isospin and energy position of isovector giant multipole resonances
The energy position Em of the dipole and quadrupole giant resonances versus the nuclear isospin T₀ is discussed. It is shown, that the proposed line E =a+bT₀ is in the better agreement with the experimental data of the dipole giant resonance, then in the case of Goldhaber-Teller and Steinwedel-Jense...
Saved in:
| Published in: | Вопросы атомной науки и техники |
|---|---|
| Date: | 2000 |
| Main Author: | |
| Format: | Article |
| Language: | English |
| Published: |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2000
|
| Subjects: | |
| Online Access: | https://nasplib.isofts.kiev.ua/handle/123456789/82159 |
| Tags: |
Add Tag
No Tags, Be the first to tag this record!
|
| Journal Title: | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| Cite this: | Isospin and energy position of isovector giant multipole resonances / V.M. Khvastunov // Вопросы атомной науки и техники. — 2000. — № 2. — С. 22-23. — Бібліогр.: 4 назв. — англ. |
Institution
Digital Library of Periodicals of National Academy of Sciences of Ukraine| id |
nasplib_isofts_kiev_ua-123456789-82159 |
|---|---|
| record_format |
dspace |
| spelling |
Khvastunov, V.M. 2015-05-26T08:08:14Z 2015-05-26T08:08:14Z 2000 Isospin and energy position of isovector giant multipole resonances / V.M. Khvastunov // Вопросы атомной науки и техники. — 2000. — № 2. — С. 22-23. — Бібліогр.: 4 назв. — англ. 1562-6016 PACS: 24.30.Ca https://nasplib.isofts.kiev.ua/handle/123456789/82159 The energy position Em of the dipole and quadrupole giant resonances versus the nuclear isospin T₀ is discussed. It is shown, that the proposed line E =a+bT₀ is in the better agreement with the experimental data of the dipole giant resonance, then in the case of Goldhaber-Teller and Steinwedel-Jensen models. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Nuclear reactions Isospin and energy position of isovector giant multipole resonances Изоспин и энергетическое положение изовекторных гигантских мультипольных резонансов Article published earlier |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| title |
Isospin and energy position of isovector giant multipole resonances |
| spellingShingle |
Isospin and energy position of isovector giant multipole resonances Khvastunov, V.M. Nuclear reactions |
| title_short |
Isospin and energy position of isovector giant multipole resonances |
| title_full |
Isospin and energy position of isovector giant multipole resonances |
| title_fullStr |
Isospin and energy position of isovector giant multipole resonances |
| title_full_unstemmed |
Isospin and energy position of isovector giant multipole resonances |
| title_sort |
isospin and energy position of isovector giant multipole resonances |
| author |
Khvastunov, V.M. |
| author_facet |
Khvastunov, V.M. |
| topic |
Nuclear reactions |
| topic_facet |
Nuclear reactions |
| publishDate |
2000 |
| language |
English |
| container_title |
Вопросы атомной науки и техники |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| format |
Article |
| title_alt |
Изоспин и энергетическое положение изовекторных гигантских мультипольных резонансов |
| description |
The energy position Em of the dipole and quadrupole giant resonances versus the nuclear isospin T₀ is discussed. It is shown, that the proposed line E =a+bT₀ is in the better agreement with the experimental data of the dipole giant resonance, then in the case of Goldhaber-Teller and Steinwedel-Jensen models.
|
| issn |
1562-6016 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/82159 |
| citation_txt |
Isospin and energy position of isovector giant multipole resonances / V.M. Khvastunov // Вопросы атомной науки и техники. — 2000. — № 2. — С. 22-23. — Бібліогр.: 4 назв. — англ. |
| work_keys_str_mv |
AT khvastunovvm isospinandenergypositionofisovectorgiantmultipoleresonances AT khvastunovvm izospiniénergetičeskoepoloženieizovektornyhgigantskihmulʹtipolʹnyhrezonansov |
| first_indexed |
2025-11-25T17:45:48Z |
| last_indexed |
2025-11-25T17:45:48Z |
| _version_ |
1850519082377412608 |
| fulltext |
ISOSPIN AND ENERGY POSITION
OF ISOVECTOR GIANT MULTIPOLE RESONANCES
V.M. Khvastunov
National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
The energy position Em of the dipole and quadrupole giant resonances versus the nuclear isospin T0 is discussed.
It is shown, that the proposed line E =a+bT0 is in the better agreement with the experimental data of the dipole giant
resonance, then in the case of Goldhaber-Teller and Steinwedel-Jensen models.
PACS: 24.30.Ca
Studies of giant resonances in nuclei have shown that
isoscalar (IS) and isovector (IV) resonances with an
identical multipolarity differ considerably in the energy
position. For the quadruple giant resonance the IV
resonance is located two times higher in energy than the
IS resonance. Such a substantial change in the energy
position is caused by the unit increment only of the state
isospin in the nucleus. Presently the isovector dipole
((IVD), isoscalar quadruple (ISQ) and isovector
quadruple (IVQ) giant resonances are studied most
completely. The isospin splitting observed for the IVD
resonance also affects the energy position.
80 100 120 140 160 180 200
13
14
15
16
17
A
SJ
GTEm
, M
eV
Fig. 1. The excitation energy values Em of the
isovector dipole giant resonance versus nuclear mass A.
The curves are plotted for the Goldhaber - Teller and
Steinwedel - Jensen models. The fitting parameters are
indicated in the table.
For the IVD resonance the energy position is
described by the expressions Em
J=K1
JA-1/6 (1) (Goldha-
ber−Teller model [1]) or Em
J=K2
JA-1/3 (2) (Steinwedel -
Jensen model [2]), where Em
J is the energy position of
the resonance with the spin J, K1
J and K2
J are the fitting
parameters, A is the nuclear mass. Both these
expressions are obtained from the various versions of
the hydrodynamic model. The G-T model regards a
nucleus as the rigid neutron and proton spheres, which
oscillate relative one another keeping their volumes
unchangeable. The S-J model regards a nucleus as the
neutron and proton liquids oscillating relative one
another within the limits of a rigid sphere. Both these
models show that on increasing the mass A of the
nucleus the energy Em decreases. Figure 1 shows the Em
values determined through fitting Lorentz curves to the
measured photoneutron cross sections [3]. The accuracy
of determining Em is ≤ 50 keV. The expressions (1) and
(2) were fitted to these data according to the method of
least squares. The fitting parameters obtained are given
in the Table and the curves are shown in Fig. 1. It is
seen from the figure that both models describe the
energy position of the giant dipole resonance for mean
nuclear weight only qualitatively and they differ strongly
from the values for heavy nuclei.
5 10 15 20
13
14
15
16
17
T0
E m
, M
eV
Fig. 2. The excitation energy values Em of the
isovector dipole giant resonance versus the nuclear
isospin T0. .The curve is plotted for the expression (3)
fitted to experimental data.
The energy position of the giant resonance changes with
22 ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2000, № 2.
Серия: Ядерно-физические исследования (36), c. 22-23.
.
changing the nuclear isospin T0. It decreases with T0
increasing. In expressions (1) and (2) the isospin is
neglected. To take into account the effect of the nuclear
isospin on the IVD resonance energy position, the
measured data from the (γ,n) reaction [1] were arranged
in dependence on T0. It was found that this dependence
is well described by the straight line Em=a+bT0 (3) with
the fitting parameters a and b, given in the table and in
Fig. 2. The values of the χ2 quantities characterizing the
quality of fitting to measured data show (cf. Figs. 1, 2
and the Table) that the straight line (3) furnishes a
substantially better description of data and thus it may
be used for estimating the energy position of the IVD
resonance in nuclei with the better accuracy than that of
formulas (1) and (2).
Formula Parameter values
(MeV)
χ2
1 K1=34,40 ± 0,02 1341
2 K2=76,27 ± 0,04 3047
3 a=17,32±0,02;
b=-0,183±0,002
877
50 100 150 200 250
20
22
24
26
28
30
32
34
A
E m
, M
eV
Fig. 3. The excitation energy values Em of the
isovector quadrupole giant resonance versus the
nuclear mass A. The curve is plotted for the expression
(2) fitted to experimental data.
For the IVQ resonace there are obtained much less
data than for the IVD one. Figures 3 and 4 show the
available data [4], arranged against A and T0 ,to which
the expressions (2) and (3) are fitted. Both expressions
describe the measured data sufficiently well and may be
used for estimating the IVQ resonance in other nuclei.
0 5 10 15 20 25
20
22
24
26
28
30
32
T0
E m
, M
eV
Fig. 4. The excitation energy values Em of the
isovector quadrupole giant resonance versus the
nuclear isospin T0 . The curve is plotted for the
expression (3) fitted to experimental data.
The results obtained show that the energy position of
IV giant resonances is in stronger dependence on the
isospin T0=(N-Z)/2 (the latter is determined by the
difference between the number of neutrons N and
protons Z in the nucleus), as compared with the surface
tension (G-T model) or the density (S-J model).
REFERENCIES
1. M. Goldhaber, E. Teller. On nuclear dipole
vibrations // Phys. Rev. 1948, v. 74, p. 1046-1049.
2. H. Steinwedel, J. H. D. Jensen. Hydrodinamik
von Kerndipol Schwingangen // Z. Naturforsch. 1950, v.
A5, p. 413-420.
3. B.L. Berman, B. F. Gibson, J. S. O’Connell.
Isospin shift of the energy of the giant resonance //
Phys.Lett. 1977, v. 66 B, p. 405-409.
4. F.E. Bertrand. Giant multipole resonances -
perspectives after ten years // Nucl. Phys. 1981, v. A
354, p. 129c-156c.
23
|