Electroexcitation of giant resonances in ⁵⁴Fe and ⁵⁶Fe nuclei
The investigation of giant multipole resonanсes in ⁵⁴Fe and ⁵⁶Fe nuclei has been carried out. The resonance at excitation energy of~13 MeV (51A¹/³) is shown to be of E2 type and to exist in both nuclei. In both nuclei the contribution of the E3 multipole is very small, especially of the 1 -ω branch...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
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irk-123456789-805172015-04-19T03:02:23Z Electroexcitation of giant resonances in ⁵⁴Fe and ⁵⁶Fe nuclei Khvastunov, V.M. Denyak, V.V. Ranyuk, Yu.N. Ядерная физика и элементарные частицы The investigation of giant multipole resonanсes in ⁵⁴Fe and ⁵⁶Fe nuclei has been carried out. The resonance at excitation energy of~13 MeV (51A¹/³) is shown to be of E2 type and to exist in both nuclei. In both nuclei the contribution of the E3 multipole is very small, especially of the 1 -ω branch of isovector resonance, and the E4 resonance is absent completely. Small E5 strength contribution is observed in both nuclei at excitation energy of 10 to 15 MeV. Досліджено мультипольні гігантські резонанси у ядрах 54Fe і ⁵⁶Fе. Отримано, що резонанс при енергії ~13 МеВ (51А-¹/³) є Е2 переходом і існує в обох ядрах. В обох ядрах внесок E3 переходів дуже малий, особливо 1 -ω гілки ізовекторного резонансу, а Е4 переходи взагалі відсутні. Це дуже відрізняє ⁵⁴Fe і ⁵⁶Fe від найближчих досліджених сусідів ⁵⁸Ni і ⁶⁵Cu . В обох ядрах виявлено невеликий внесок E5 сили при енергіях збудження 10…15 МеВ. Исследованы мультипольные гигантские резонансы в ядрах ⁵⁴Fe и ⁵⁶Fe. Получено, что резонанс при энергии ~13 МэВ (51А-¹/³) является E2 переходом и существует в обоих ядрах. В обоих ядрах вклад E3 переходов очень мал, особенно 1 -ω ветви изовекторного резонанса, а E4 переходы вообще отсутствуют. Это сильно отличает ⁵⁴Fe и ⁵⁶Fe от ближайших исследованных соседей ⁵⁸Ni и ⁶⁵Cu. В обоих ядрах обнаружен небольшой вклад Е5 силы в области энергий возбуждения 10…15 МэВ. 2004 Article Electroexcitation of giant resonances in ⁵⁴Fe and ⁵⁶Fe nuclei / V.M. Khvastunov, V.V. Denyak, Yu.N. Ranyuk // Вопросы атомной науки и техники. — 2004. — № 5. — С. 26-30. — Бібліогр.: 12 назв. — англ. 1562-6016 PACS: 24.30.Ca http://dspace.nbuv.gov.ua/handle/123456789/80517 en Вопросы атомной науки и техники Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Ядерная физика и элементарные частицы Ядерная физика и элементарные частицы |
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Ядерная физика и элементарные частицы Ядерная физика и элементарные частицы Khvastunov, V.M. Denyak, V.V. Ranyuk, Yu.N. Electroexcitation of giant resonances in ⁵⁴Fe and ⁵⁶Fe nuclei Вопросы атомной науки и техники |
| description |
The investigation of giant multipole resonanсes in ⁵⁴Fe and ⁵⁶Fe nuclei has been carried out. The resonance at excitation energy of~13 MeV (51A¹/³) is shown to be of E2 type and to exist in both nuclei. In both nuclei the contribution of the E3 multipole is very small, especially of the 1 -ω branch of isovector resonance, and the E4 resonance is absent completely. Small E5 strength contribution is observed in both nuclei at excitation energy of 10 to 15 MeV. |
| format |
Article |
| author |
Khvastunov, V.M. Denyak, V.V. Ranyuk, Yu.N. |
| author_facet |
Khvastunov, V.M. Denyak, V.V. Ranyuk, Yu.N. |
| author_sort |
Khvastunov, V.M. |
| title |
Electroexcitation of giant resonances in ⁵⁴Fe and ⁵⁶Fe nuclei |
| title_short |
Electroexcitation of giant resonances in ⁵⁴Fe and ⁵⁶Fe nuclei |
| title_full |
Electroexcitation of giant resonances in ⁵⁴Fe and ⁵⁶Fe nuclei |
| title_fullStr |
Electroexcitation of giant resonances in ⁵⁴Fe and ⁵⁶Fe nuclei |
| title_full_unstemmed |
Electroexcitation of giant resonances in ⁵⁴Fe and ⁵⁶Fe nuclei |
| title_sort |
electroexcitation of giant resonances in ⁵⁴fe and ⁵⁶fe nuclei |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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2004 |
| topic_facet |
Ядерная физика и элементарные частицы |
| url |
http://dspace.nbuv.gov.ua/handle/123456789/80517 |
| citation_txt |
Electroexcitation of giant resonances in ⁵⁴Fe and ⁵⁶Fe nuclei / V.M. Khvastunov, V.V. Denyak, Yu.N. Ranyuk // Вопросы атомной науки и техники. — 2004. — № 5. — С. 26-30. — Бібліогр.: 12 назв. — англ. |
| series |
Вопросы атомной науки и техники |
| work_keys_str_mv |
AT khvastunovvm electroexcitationofgiantresonancesin54feand56fenuclei AT denyakvv electroexcitationofgiantresonancesin54feand56fenuclei AT ranyukyun electroexcitationofgiantresonancesin54feand56fenuclei |
| first_indexed |
2025-07-06T04:31:43Z |
| last_indexed |
2025-07-06T04:31:43Z |
| _version_ |
1836870589453697024 |
| fulltext |
ELECTROEXCITATION OF GIANT RESONANCES
IN 54Fe AND 56Fe NUCLEI
V.M. Khvastunov, V.V. Denyak, Yu.N. Ranyuk
National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
e-mail: khvastunov@kipt.kharkov.ua
The investigation of giant multipole resonanсes in 54Fe and 56Fe nuclei has been carried out. The resonance at
excitation energy of~13 MeV (51A1/3) is shown to be of E2 type and to exist in both nuclei. In both nuclei the
contribution of the E3 multipole is very small, especially of the 1ω branch of isovector resonance, and the E4
resonance is absent completely. Small E5 strength contribution is observed in both nuclei at excitation energy of 10
to 15 MeV.
PACS: 24.30.Ca
1. INTRODUCTION
The investigation of giant resonance (GR)
electroexcitation in various nuclei with the help of the
inelastic scattering of electrons was carried out
intensively during the last decades. The big volume of
information was accumulated about the excitation
energy, width and energy weighted sum rule (EWSR)
exhausting for nearly 40 nuclei. However, the giant
resonances were studied and systematized well enough
only in heavy nuclei (for A>90), where the results are in
good agreement with the proton and α-particle
scattering [1]. In the region of intermediate nuclei with
40≤A≤90 the agreement of the experimental results with
different scattered particles is not good enough and still
remains a number of unresolved fundamental questions.
During many years there is a problem with isoscalar
giant monopole resonance (ISGMR) in nuclei with A≤
90. The EWSR exhausting for these nuclei are
significantly smaller 100 %. Recently for several nuclei
there were obtained the α-scattering experimental
results [2], that shows the existence of high energy
“tail” up to excitation energy of 35 MeV in the ISGMR
strength distribution. Taking into account this “tail” the
EWSR exhausting should be increased up to 100 % for
90Zr and up to 60 % for nuclei with smaller A – 28Si,
40Ca, 58Ni. It is still unclear where the rest part of
ISGMR might be located. From the theoretic point of
view there is no obvious reason to suggest ISGMR
vanishing in light nuclei. But it is known that in light
nuclei the strengths of other GRs are spread over a large
range of excitation energy. If such behavior is typical
for ISGMR, this will cause a significant difficulties in
observing the E0 strength localization.
The multipole resonance investigation in the mass
region A~60 is of great interest also due to the
discovery of additional E2 GR. The distinct resonant
excitations at 13 MeV (51A-1/3) in 58Ni, 60Ni, and 64Ni
were first observed in Kharkov [3] in inelastic electron
scattering and identified as E2 resonance [4]. Other
experiments, which found structure at this energy (~(50-
53)A-1/3 MeV) in nuclei with 56≤A≤60, partly support
and partly disagree with the E2 multipole assignment
[5]. The discovered resonance is situated at lower
excitation energy, than isoscalar E2 GR (63A-1/3).
Besides, the EWSR nuclear mass dependence of this
resonance differs significantly from the one of the main
isoscalar E2 GR [5,6]. The authors of [5,6] analyzed this
situation and drew a conclusion that the resonance at the
excitation energy 51A-1/3 is the isovector quadrupole
resonance and perhaps it’s manifestation depends on the
neutron excess. This resonance is not observed in nuclei
with lower A.
We have carried out the investigation of electric
giant multipole resonance excitation in 54Fe and 56Fe
nuclei. These nuclei are situated in the mass region
where the ISGMR manifestation differs from the heavy
nuclei systematic (A>90), and the additional E2
resonance vanishes almost completely. The absence of
information even about the electric dipole GR excitation
[7] in spite of wide occurrence of these nuclei is another
stimulus to choose them for study.
There is only one paper [8] in literature where the
preliminary results of such type investigation are
represented and only for 56Fe. The excitation energy
range has been extended in our experiment comparing
with paper [8] to cover the energy region of quasielastic
(QE) excitation. This allowed to account the QE process
contribution more correctly. The transferred momentum
range was extended up to 1,7 Fm-1 that made it possible
to investigate resonances up to E5. The method of
dividing the scattered electron spectra into successive
bins (“bin method”) with their subsequent analysis was
used instead of separating the individual peak in the
initial spectrum as it was done in paper [8]. The
advantage of the “bin method” in comparison with
individual peak adjustment is the possibility to reveal
the contributions of different multipoles at the same
excitation energy. This advantage can be clearly seen in
paper [9] where the “bin” technique was first applied for
treating spectra of inelastically scattered electrons in the
range of discrete level energy excitation. The “bin”
technique permitted to discover additional, weaker
levels not observed earlier in (e,e′) experiments against
the background of strongly excited levels and to
determine their spins and parities. To understand the
“bin method” influence on the final results of multipol
analysis we have treated out the initial experimental
26 PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2004, № 5.
Series: Nuclear Physics Investigations (44), p. 26-30.
data of the paper [8] with the help of this method and
compared the results with those of paper [8].
2. THE EXPERIMENTAL TECHNIQUE AND
DATA PROCESSING
The experiment was carried out at the LINAC-300
of NSC KIPT. Eight spectra were measured for each
nucleus at electron initial energy of 225 MeV for the
angles from 40o to 75o with a step of 5o. In the energy
range of giant resonances excitation (up to 40 MeV) the
measurements were carried out continuously, and in the
range of QE scattering (~40 … 150 MeV) they were
done by means of 3 MeV wide bunches with the spaces
of the same width.
The description of the experimental equipment,
methods of measuring spectra of scattered electrons and
processing the data obtained may be found in [9] and
references therein.
Besides operations described in [9], taking into
account the QE processes plays a significant role while
studying the giant resonances. Their contribution to
scattered electron spectra depends on the excitation
energy and amounts to dozens percents. The problem of
correct spectrum splitting into QE and resonance cross
sections remains to be unresolved up to now. The shape
of the energy dependence of QE cross section at
excitation energies lower than QE maximum is not
known even qualitatively. In different papers the authors
use various semi-empirical methods for giant
resonances separation against the QE background. We
have carried out two different data treatments with two
shapes of QE background energy dependence to
estimate the effect of this background extraction on the
final result.
In the first case the QE spectrum was approximated
by Gaussian and was fitted by least square method to
experimental data in the excitation energy range equal
to and higher than the QE maximum for each spectrum
of scattered electrons. In addition it had to vanish at the
QE threshold to the accuracy of experimental errors.
Such approach gives good description of the cross
section energy dependence higher the QE maximum.
In the second case the QE background was
approximated with a straight line starting from the
origin of coordinates and crossing the measured
spectrum at the energy corresponding to the QE
maximum. The QE cross section calculated on the
ground of the Fermi-gas model possesses such a linear
dependence. But it seems impossible to use the exact
Fermi-gas calculations because their absolute values are
in a poor agreement with measured data.
The example of the QE cross section energy
dependence for both cases is represented in Fig.1.
Further the QE cross section was subtracted from the
experimental data, then spectra were divided into bins
and form factor for each bin was a subject of multipol
analysis.
Fig. 1. The scattered electron spectrum. The
elastic peak is subtracted. The curves show two
methods of QE cross section calculation: Gaussian –
solid curve, straight line –dashed curve
Besides, we have used the photo cross section [10]
for more careful identification of the dipole strength.
It’s value was recalculated into the electric Coulomb
form factor for small momentum transfer according to
the equations of paper [11].
While treating the experimental data of paper [8],
the E1-E5 multipoles were fitted in accordance with the
range of momenta transferred in experiment. In this case
we had not possibility to account the QE background
correctly because the experimental spectra were
measured not far enough over the excitation energy.
That’s why two methods were used for the data
treatment. In the first case the QE background under the
giant resonances was taken with the same way as it was
in paper [8], i.e., it was constant and not depended on
the excitation energy for each given spectrum. But such
an approach gives the improbable result at small
excitation energy. Namely, near the threshold, where the
QE cross section has to vanish, it’s value is still very big
- 90 % and more of the total cross section. That’s why
in the second case the QE background was taken as a
strait line that exhausts the cross section in the QE
maximum and is equivalent to zero in the threshold.
This make it possible to compare the QE background
shape influence on the final result.
3. RESULTS AND DISCUSSION
Figs. 2,3 represent the reduced transition probability
B(Eλ) for each multipolarity λ. The comparison of
results obtained by us between themselves and with the
results of work [8] is shown in Tables 1,2. The
determination of the individual peak excitation energy,
reduced transition probability and width was
accomplished by least square fitting of Gaussian to the
experimental data. The EWSR was taken to be isovector
for E1 transitions and the general for other
multipolarities.
3.1. The processing of data from paper [8] for 56Fe
In the E1 strength distribution one can see the first
not big peak at low energy ~10 MeV and another broad
one with the maximum at ~16 MeV. The broad peak
27
increases sharply at low energy and decreases smoothly
at high energy. This means that it consists at least of two
peaks with different magnitude and width. So we
approximated this broad peak with two Gaussians.
From Table 1 one can see that the excitation energy
and reduced transition probability of the low-energy
peak depend on the QE background. But this resonance
exists in both cases, when the QE background near the
10 MeV is maximum (constant background) and when it
is equivalent to zero (the background is falling down
linearly at the low energies).
There is also the strong QE background dependence
of the high-energy peak excitation energy. The
characteristics of another resonance depend on QE
background too little.
The both methods of QE background consideration
give some strength in the energy range above 30 MeV.
In the case of constant background it even looks like
peak. But the existence of resonance at this range is
doubtful. This might lead to the second peak with the
approximately the same magnitude in the photo cross
section. Such situation is not observed not only in 56Fe
but in all neighboring nuclei (see for example [7]).
Besides, even without this peak the E1 strength exhausts
more than 100 % of the EWRS for isovector resonances.
The existence of this peak most likely indicates that the
QE background, which is dominant at high excitation
energies, was not subtracted correctly in both cases.
Fig. 2. The reduced transition probability B(Eλ)
for 56Fe nuclei data from paper [8]. Left part – the
background was subtracted as in paper [8], right part –
as increasing straight line (see text above)
Table 1. Parameters of the giant resonances in 56Fe
Eλ Eres, MeV ∆Е, MeV B(Eλ), fm2λ
e2
EWRS, %
Е1 10.1±0.1
11.3±0.5
10.3±0.3
10.3±0.3
0.9±0.1
1.4±0.6
0.2±0.1
0.2±0.1
2.96±0.39
0.73±0.24
0.05±0.03
0.05±0.03
14±2 1)
4±1 2)
<1 3)
<1 4)
16.3±0.1
16.0±0.2
14.6±0.3
15.0±0.4
3.2±0.2
1.6±0.2
1.3±0.2
1.5±0.3
11.89±0.79
2.65±0.55
1.00±0.14
1.00±0.14
93±6 1)
21±4 2)
7±1 3)
7±3 4)
23.9±0.3
19.8±0.3
18.3±0.1
18.2±0.1
19.0±.05
4.0±0.5
4.0±0.1
2.3±0.1
2.5±0.1
9.55±0.59
9.61±0.52
6.71±0.36
6.68±0.36
110±7 1)
92±6 2)
59±3 3)
59±3 4)
5)
217±9 1,6)
117±7 2,6)
66±3 3,6)
66±4 4,6)
Е2
or
E0
1-8 917±42
892±42
13±1 3)
13±1 4)
9.5±0.1
9.5±0.1
0.7±0.1
0.7±0.1
137±23
130±41
4±1 3)
4±1 4)
13.0±0.3
13.1±0.1
13.0±0.9
11.9±0.9
1.5±0.6
1.0±0.1
2.5±0.2
1.5±0.6
312±6
92±5
642±59
205±93
13±3 1)
4±1 2)
27±3 3)
8±3 4)
17.3±0.1
16.9±0.1
17.9±0.2
15.6±1.2
16.1±.05
2.5±0.1
2.4±0.3
2.4±0.2
2.6±0.7
510±12
266±6
343±41
401±181
672
28±1 1)
14±3 2)
20±2 3)
20±9 4)
34 5)
23.8±0.4
27.7±0.3
25.0±0.3
22.8±0.5
32.0±.05
3.7±0.3
4.3±0.4
6.0±0.5
7.7±0.3
192±15
121±10
1004±23
1099±62
15±1 1)
11±1 2)
80±2 3)
73±4 4)
5)
56±3 1,6)
29±3 2,6)
144±4 3,6)
118±10 4,6)
Е3 4-9 32463±898
31488±898
10±1 3)
10±1 4)
13.3±.05 5)
35.8±0.9
38.2±0.6
4.7±0.9
6.4±0.9
4157±694
9601±1069
8±1 3)
19±2 4)
E5 12.4±0.3
11.5±0.4
3.8±0.5
3.7±0.6
(33±3)106
(26±3)106
5±1 3)
4±1 4)
1,2) The data of work [8] treatment. 1) The QE
background was subtracted as increasing strait line
(see text above). 2) The QE background was subtracted as in
[8].
3,4)Our experiment. 3) The QE background was
approximated by Gaussian.. 4) The QE background -
straight line (see text above).
5) Results of paper [8].
28
6)The total EWSR exhausting for resonances with this
multipolarity.
In the E2(E0) strength distribution there are two
strongly overlapping peaks and one very week peak at
high excitation energies. The magnitude of the low-
energy peak depends strongly on the QE background. In
the paper [8] this peak was identified as the E3
resonance.
The energy position of the resonance at the highest
energy we have obtained is lower than in [8]. But, as
can be seen in Table 1, the QE background influences
on it’s position strongly. Besides, the cross section
higher than 30 MeV was included in [8] in this
resonance while in our treatment it manifests partly as
E1 strength. Such difference leads to the shift of the
peak maximum to higher excitation energies.
The analysis of the EWSR magnitude shows, that
there is a systematic error in the results obtained. The
E1 isovector strength exhausts more than 100 % but the
E2 strength is very week. This conclusion does not
depend on the QE background shape and on the low
energy E2 transition contribution, not measured in [8].
Most likely it should be a big contribution of
background not connected with the QE scattering in
spectra of paper [8].
Fig. 3. The reduced transition probability for 56Fe
nuclei obtained in our experiment. Left part – the QE
background was approximated by Gaussian, right part
– by straight line (see text above)
3.2. Results of our experiment
The magnitude and shape of E1 resonance obtained
by us is under the strong influence of photo cross
section. It has to be mentioned that the photo cross
section used by us is the theoretic one from the paper
[10], because the experimental data for 56Fe is
completely absent. We used three Gaussians for fitting
to compare with the results of previous section.
As it is seen in Table 1, the difference in the
excitation energy is 1…2 MeV while the difference in
the reduced transition probability is several times. The
biggest difference is for the low energy resonance. This
is not the result of our experiment but due to the usage
of photon cross section which is almost equivalent to
zero at 10…11 MeV.
Table 2. Parameters of the giant resonances in 54Fe
Eres, MeV ∆Е, MeV B(Eλ), fm2λ
e2
EWRS, %
Е1
15.0±1.3
15.0±0.9
1.4±0.2
1.4±0.2
0.79±0.17
0.81±0.17
6±11)
6±12)
19.2±0.1
19.2±0.1
2.4±0.1
2.4±0.1
10.0±0.2
10.0±0.2
96±21)
96±22)
112±21,3)
112±22,3)
Е2
1-8 1742±43
1707±43
26±11)
26±12)
9.7±0.1
9.7±0.1
0.7±0.1
0.7±0.1
175±25
151±19
6±11)
5±12)
13.4±0.2
13.8±0.2
2.4±0.2
2.7±0.2
764±89
859±66
35±41)
41±32)
17.5±0.2
17.9±0.2
1.3±0.2
1.1±0.2
175±54
126±43
10±31)
8±32)
23.9±0.3
25.4±0.4
6.8±0.2
6.2±0.3
1459±60
1016±50
119±51)
88±52)
196±71,3)
168±72,3)
Е3
4-9 30082±605
28765±605
12±11)
11±12)
20.3±0.1
20.2±0.1
0.6±0.2
0.6±0.1
1480±341
1529±323
2±11)
2±12)
36.2±0.5
38.3±0.4
4.7±0.6
5.3±0.5
6628±670
10871±802
14±11)
25±22)
E5
12.4±0.5
12.6±0.4
2.0±0.4
2.1±0.5
(12±2)106
(12±2)106
2±11)
3±12)
1)The QE background was approximated by Gaussian.
2)The QE background - as straight line (see text above).
3)The total EWSR exhausting for resonances with this
multipolarity.
In the E2 strength distribution we found four
resonances. The low energy resonance was not observed
in the treatment of paper [8] because of the excitation
energy was too low. The rather big magnitude of this
resonance depends strongly on the photon cross section
magnitude. The additional test fittings show that a not
big increase of the photo cross section at this excitation
energy leads to a significant increase in the low energy
E1 resonance strength and to the decrease of the
corresponding E2 resonance. The significant difference
29
in B(E2) for the high energy resonance is due to the QE
background.
There is E3 resonance in our results at excitation
energy 35,8 MeV that corresponds to 3ω branch of the
E3 resonance. In the results of paper [8] this resonance
could not be separated from the high energy E2
resonance due to the lack of the data treatment method.
In our treatment this resonance is also not observed. But
there is unlikely big E1 strength at this energy. Probably
the reason of this “transfer” of E3 strength to the E1
strength is the impossibility to subtract correctly the QE
background from the data of paper [8].
The results obtained for 54Fe are very similar to
results for 56Fe (see Table 2). In addition in 54Fe there is
the E3 resonance at ~20 MeV, corresponding to the 1ω
branch of E3 resonance.
4. CONCLUSIONS
The investigation of the multipole giant resonances
in 54Fe and 56Fe accomplished allows to make a number
of conclusions:
1. The resonance at excitation energy
13 MeV(51A1/3) is not E3 one but E2 resonance and it
exists in both nuclei.
2. In both nuclei the cross section is exhausted
mainly by E1 and E2 multipoles. The contribution of the
E3 multipole is very small, especially of the 1ω branch
of isovector resonance, and the E4 resonance is absent
completely. This differ them greatly from the nearest
neighbors – 65Cu [12], 58Ni [5].
3. The small contribution of the E5 strength was
found in both nuclei in the energy excitation range 10…
15 MeV.
REFERENCES
1. A. van der Woude. The Electric Giant Resonances //
International Review of Nuclear Physics, 1991, v. 7,
p. 99-232.
2. A. van der Woude. Summary of Electric Giant
Resonances in Cold Nuclei // Nucl. Phys. 1999,
v. A649, p. 97c-103c.
3. I.S. Gulkarov, N.G. Afanasev, V.M. Khvastunov et
al. Excitation of giant resonance in Ni isotopes by means
of high energy electrons // Sov. J. Nucl. Phys. 1969, v. 9,
p. 274-280.
4. V.M. Khvastunov, V.P. Berezovoy, V.P. Likhachev et
al. The isospin effect on the electroproduction of the
giant dipole resonance in nickel isotopes // Sov. J. Nucl.
Phys. 1977, v. 25, p. 491-494.
5. R. Pitthan et al. Comparison of giant multipole
resonances of multipolarity E1 to E4 in 58Ni(T0=1)
and 60Ni(T0=2) with inelastic electron scattering //
Phys. Rev. 1980, v. C21 (1), p. 147-166.
6. R. Pitthan et al. E0, E1, E2, E3, and E4 giant
resonances in the N=82 nucleus 140Ce between 4 and
48 MeV excitation energy with inelastic electron
scattering // Phys. Rev. 1979, v. C19, p. 1251-1275.
7. A.V. Varlamov, V.V. Varlamov, D.S. Rudenko,
M.E. Stepanov. Atlas of Giant Dipole Resonances..
IAEA Nuclear Data, Wagramerstrasse 5, A-1400,
Vienna, January 1999.
8. Y. Torizuka, Y. Kojima, N. Saito et al. Giant
Resonances other than E1. Proc. of Intern. Conf. on
Photonuclear Reactions and Applications. Oak
Ridge, Tennessee, 1973, p.675-683.
9. V.V. Denyak, V.M. Khvastunov, V.P. Likhachev et
al. Excitation of Discrete Levels in 54Fe and 56Fe
Nuclei by means of (e,e') Reactions // Physics of
Atomic Nuclei, 2004, v. 67, no 5, p. 882-889.
10. S.S. Borodina, A.V. Varlamov, V.V. Varlamov et al.
54,56Fe and 58,60Ni(γ, n), (γ, n), (γ, pn) and (γ, 2n)
reaction cross sections evaluation using the model
of GDR state decay channel competition
phenomenological description. Preprint of MSU
NPI-2000-6/610, 2000, 17p.
11. H. Uberall. Electron scattering from complex nuclei.
New York and London. “Academic Press”, 1971, parts
A, B.
12. G.A. Savitsky, V.A. Fartushny I.G. Evseev et al.
Electron excitation of giant multipole resonances in 65Cu
nucleus // Sov. J. Nucl. Phys. 1987, v. 46, p. 29-32.
ЭЛЕКТРОВОЗБУЖДЕНИЕ ГИГАНТСКИХ РЕЗОНАНСОВ В ЯДРАХ 54Fe И 56Fe
В.M. Хвастунов, В.В. Деняк, Ю.Н. Ранюк
Исследованы мультипольные гигантские резонансы в ядрах 54Fe и 56Fe. Получено, что резонанс при
энергии ~13 МэВ (51А-1/3) является E2 переходом и существует в обоих ядрах. В обоих ядрах вклад E3
переходов очень мал, особенно 1ω ветви изовекторного резонанса, а E4 переходы вообще отсутствуют. Это
сильно отличает 54Fe и 56Fe от ближайших исследованных соседей 58Ni и 65Cu. В обоих ядрах обнаружен
небольшой вклад Е5 силы в области энергий возбуждения 10…15 МэВ.
ЕЛЕКТРОЗБУДЖЕННЯ ГИГАНТСЬКИХ РЕЗОНАНСІВ У ЯДРАХ 54Fe И 56Fe
В.M. Хвастунов, В.В. Деняк, Ю.М. Ранюк
Досліджено мультипольні гігантські резонанси у ядрах 54Fe і 56Fе. Отримано, що резонанс при енергії
~13 МеВ (51А-1/3) є Е2 переходом і існує в обох ядрах. В обох ядрах внесок E3 переходів дуже малий,
особливо 1ω гілки ізовекторного резонансу, а Е4 переходи взагалі відсутні. Це дуже відрізняє 54Fe і 56Fe від
найближчих досліджених сусідів 58Ni і 65Cu . В обох ядрах виявлено невеликий внесок E5 сили при енергіях
збудження 10…15 МеВ.
30
National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
PACS: 24.30.Ca
EWRS, %
13.3.05
5)
EWRS, %
Е1
Е2
Е3
E5
REFERENCES
В.M. Хвастунов, В.В. Деняк, Ю.М. Ранюк
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