Searching the analogue 2p₃/₂-resonance in the ³⁶S(p,γ)³⁷Cl reaction
Searching the analogue 2p₃/₂-resonance in ³⁷Cl, which is an isobaric analogue of the parent level with E* = 0.646 MeV (Jp = 3/2-) of ³⁷S was carried out. The excitation function for the ³⁶S(p,g)³⁷Cl reaction was measured in the energy region Ep = 2487 - 2680 keV. Resonance strengths were determined...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2002
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| Cite this: | Searching the analogue 2p₃/₂-resonance in the ³⁶S(p,γ)³⁷Cl reaction / A.N. Vodin, I.V. Ushakov, A.S. Kachan, L.P. Korda, V.M. Mischenko, B.A. Nemashkalo // Вопросы атомной науки и техники. — 2002. — № 2. — С. 30-32. — Бібліогр.: 7 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859620432859103232 |
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| author | Vodin, A.N. Ushakov, I.V. Kachan, A.S. Korda, L.P. Mischenko, V.M. Nemashkalo, B.A. |
| author_facet | Vodin, A.N. Ushakov, I.V. Kachan, A.S. Korda, L.P. Mischenko, V.M. Nemashkalo, B.A. |
| citation_txt | Searching the analogue 2p₃/₂-resonance in the ³⁶S(p,γ)³⁷Cl reaction / A.N. Vodin, I.V. Ushakov, A.S. Kachan, L.P. Korda, V.M. Mischenko, B.A. Nemashkalo // Вопросы атомной науки и техники. — 2002. — № 2. — С. 30-32. — Бібліогр.: 7 назв. — англ. |
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| container_title | Вопросы атомной науки и техники |
| description | Searching the analogue 2p₃/₂-resonance in ³⁷Cl, which is an isobaric analogue of the parent level with E* = 0.646 MeV (Jp = 3/2-) of ³⁷S was carried out. The excitation function for the ³⁶S(p,g)³⁷Cl reaction was measured in the energy region Ep = 2487 - 2680 keV. Resonance strengths were determined for 44 resonances. The decay schemes and branching ratios of four resonances were investigated at Ep = 2539, 2599, 2659 and 2676 keV. Spins and parities of these resonances (3/2⁺, 3/2⁺, 3/2⁺ and 5/2⁺, correspondingly) were established from angular distributions of γ-rays and measured intensities of γ-transitions.
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| first_indexed | 2025-11-29T03:09:21Z |
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SEARCHING THE ANALOGUE 2p3/2-RESONANCE
IN THE 36S(p,γ)37Cl REACTION
A.N. Vodin, I.V. Ushakov, A.S. Kachan, L.P. Korda,
V.M. Mischenko, B.A. Nemashkalo
National Scientific Centre “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
e-mail: vodin@kipt.kharkov.ua
Searching the analogue 2р3/2-resonance in 37Cl, which is an isobaric analogue of the parent level with E* = 0.646
MeV (Jπ = 3/2-) of 37S was carried out. The excitation function for the 36S(p,γ)37Cl reaction was measured in the ener-
gy region Ep = 2487 - 2680 keV. Resonance strengths were determined for 44 resonances. The decay schemes and
branching ratios of four resonances were investigated at Ep = 2539, 2599, 2659 and 2676 keV. Spins and parities of
these resonances (3/2+, 3/2+, 3/2+ and 5/2+, correspondingly) were established from angular distributions of γ-rays
and measured intensities of γ-transitions.
PACS: 25.40. Lw, 23.20.-g, 23.20. En, 23.20. Gq, 23.20. Js, 23.20. Lv
1. INTRODUCTION
The 36S(p,γ)37Cl reaction has been the subject of fre-
quent investigation, almost exclusively at proton ener-
gies below Ep = 2 MeV. The exception is the work [1],
performed with a NaJ-detector in the energy region
Ep = 2300 - 3200 keV. The resonances up to Ep = 2
MeV have been investigated in detail in [2]. Decay
schemes and lifetimes of a number of resonances and
bound states of 37Cl have been measured in those experi-
ments. A substantial study of the analogue 1f7/2-reso-
nance at Ep = 1887 keV have been made in [3,4].
The aim of the present work was to search the ana-
logue 2p3/2-resonance in 37Cl, which is an isobaric ana-
log of the first excited level of the parent nucleus 37S
with E* = 0.646 MeV (Jπ = 3/2-). In this connection a se-
ries of researches was carried out. The excitation func-
tion of the 36S(p,γ)37Cl reaction was studied in vicinity of
the analogue 2p3/2-resonance (Ep ≈ 2.6 МeV), γ-decay
schemes of the most intensive resonances at Ep = 2539,
2599, 2659 and 2676 keV were defined and the angular
distributions of the γ-rays were measured.
2. EXPERIMENTAL PROCEDURE
The experiments were performed with the proton
beam from the 3 MeV Van de Graaf accelerator at the
Nuclear Spectroscopy Laboratory of NSC “KhIPT”. A
target of approximately 2 keV thickness at Ep = 2 MeV
consisting of Ag2S (81.1 % 36S) was used. A beam cur-
rent of 20 µA was maintained during the experiments.
The γ-radiation was detected with a 70 cm3 Ge(Li)-
detector (full width at half maximum was equal to
3.1 keV at 1.332 MeV) coupled to a 4096 channel ana-
lyzer. The detector was at an angle θlab = 55° in relation
to a proton beam. The Ge(Li)-detector efficiency was
determined with calibrated standard sources and using
relative γ-ray intensities in the 27Al(p,γ)28Si reaction [5].
The angular distributions of γ-rays, arising from the
decay of resonance states in 37Cl, were measured at an-
gles 0°, 30°, 45°, 60° and 90° concerning a proton beam
direction. As a radiation monitor a current integrator
and additionally a spectrometer on the basis of
a ∅ 150 × 100 mm NаJ(Тl) crystal were used. This de-
tector was used to obtain a yield curve of the 36S(p,γ)37Cl
reaction as a function of proton energy.
3. RESULTS OF MEASUREMENTS
3.1. EXCITATION FUNCTION
In the present investigations the excitation function
of the 36S(p,γ)37Cl reaction was measured in the proton
energy region Ер = 2487 - 2680 keV. Measurements
were carried out with ∆Ер = 0.8 keV. The yield curve of
the 36S(p,γ)37Cl reaction registered by the NaJ(Тl)-detec-
tor at an angle θlab = 55° with respect to a proton beam
direction is represented in fig. 1. Measurements were
done with the Еγ > 6.13 MeV discrimination threshold
for energy of γ-rays.
2500 2550 2600 2650
6000
12000
Ep, keV
Nγ
Fig.1. The excitation function of the 36S(p,γ)37Cl reac-
tion in the energy region Ер = 2480 - 2680 keV, θlab = 55°
The experimentally observable widths of resonances
indicated in fig.1 are equal approximately to 2.8 keV
and are stipulated by a final thickness of a target and en-
ergy scatter in a proton beam.
The results obtained at the analysis of the excitation
function of the 36S(p,γ)37Cl reaction are represented in
Table 1, in which the data from [1] are also introduced.
30 PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2002, № 2.
Series: Nuclear Physics Investigations (40), p. 30-32.
Table 1. Strengths of resonances in the 36S(p,γ)37Cl reaction
E
p
, keV E
*
, MeV S, eV E
p
, keV
a)
E
p
, keV E
*
, MeV S, eV E
p
, keV
a)
E
p
, keV E
*
, MeV S, eV E
p
, keV
a)
2489.0 10.8081 0.03 2547.1 10.8646 2.2 2613.0 10.9287 0.09
2491.3 10.8103 0.05 2551.8 10.8692 0.18 2617.7 10.9333 0.17
2494.8 10.8137 0.01 2493 2555.3 10.8726 0.52 2622.5 10.9380 1.9
2498.3 10.8171 0.57 2561.2 10.8783 1.3 2627.2 10.9425 0.15
2502.9 10.8216 2.2 2502 2565.8 10.8828 0.32 2630.8 10.9460 0.04
2508.7 10.8272 1.0 2510 2569.4 10.8863 0.09 2634.3 10.9494 0.21
2512.2 10.8306 3.2 2574.1 10.8909 0.16 2572 2639.1 10.9541 0.32
2514.5 10.8329 0.83 2577.6 10.8943 1.8 2642.7 10.9576 0.16
2518.0 10.8363 0.07 2520 2579.9 10.8965 0.10 2646.8 10.9616 8.3
2522.6 10.8408 0.02 2583.5 10.9000 0.63 2651.0 10.9657 0.43
2525.0 10.8431 6.7 2588.2 10.9046 0.28 2658.8 10.9733 7.4 2657
2529.6 10.8476 2.3 2592.9 10.9092 0.07 2593 2662.9 10.9773 1.2
2531.9 10.8498 4.5 2598.8 10.9149 9.1 2667.7 10.9819 1.1
2538.9 10.8566 4.0 2541 2605.3 10.9212 1.3 2676.1 10.9901 6.0
2543.6 10.8612 5.0 2608.3 10.9241 0.11
Note: the values Ер are indicated with an error ± 0.8 keV, a) - data from [1]
3.2. RESONANCE DECAY SCHEMES
Based on balance of energy values and intensities of
observed γ-transitions the γ-decay schemes of investi-
gated resonances were defined in view of all known
data on levels of the 37Cl nucleus. The branching ratios
b(γ) for resonances at Ep = 2539, 2599, 2659 and
2676 keV are represented in Table 2.
3.3. ANGULAR DISTRIBUTIONS OF γ-RAYS
The data on parameters of mixing ratios δ are neces-
sary for account of probabilities of direct γ-transitions.
In this connection the angular distributions of γ-rays
were measured and on the basis of their analysis the δ
values were determined. The function of angular corre-
lation was searched as expansion on even polynomials
of Legendre:
)θ(cos)θ(cos1)θ( 4422 PaPaW ++= , (1)
where the coefficients a2 and a4 depend on an angular
moment of initial and final states and a parameter δ. The
a2 and a4 coefficients, found using the method of least
squares, were compared to their theoretical values for
various hypotheses about a spin J of a resonance level
and appropriate δ value with the help of criterion 2χ .
The combination of J and δ was rejected, if the ob-
tained value 2
min
2 χχ ≡ exceeded probable 0.1%-limit.
The defined thus a2 and a4 coefficients in the function of
angular distribution of γ-rays and δ values, appropriate
to them, are represented in tab. 2. The corrections which
take into account a final solid angle of the Ge(Li)-detec-
tor are brought into results of measurements. The indi-
cated errors are standard deviations.
3.4. RESONANCE STRENGTHS
AND γ-WIDTHS
For determination of the absolute yield of γ-rays
from the 36S(p,γ)37Cl reaction the comparison of re-
searched resonances with the resonance at
Ер = 1887 keV was carried out. The strength for the last
one was equal to [4]:
eV331)12( γp ±=+=
Г
ГГ
JS , (2)
31
where J - a spin of a resonance state, Гр, Гγ and Г - pro-
ton, radiation and total widths of a resonance. The eval-
uation of values of a radiation resonance width was car-
ried out in assumption that Гр >> Гγ.
The experimental values of probabilities of γ-transi-
tions between resonances and bound states of 37Cl based
on obtained data were determined. It allowed to deter-
minate the parities of resonance states taking in consid-
eration recommended upper limits (RUL's) for probabil-
ities of electromagnetic γ-transitions in nuclei with
А < 44 [6].
4. DISCUSSION
4.1. RESONANCE STATES
Col.3 of table 2 shows the spins and parities of the
resonance and bound levels of 37Cl. The RUL's used
were 0.1 W.u. for E1, 100 W.u. for E2, 10 W.u. for M1
and 3 W.u. for M2-transitions [6].
The Ер = 2539 keV resonance. Results of the angular
distribution measurements revealed that J = 3/2 gives
the 2χ value below the 0.1% confidence limit for the
r → 0 and r → 1.727 MeV transitions. Both transitions
exclude J = 1/2, whereas J = 5/2 is excluded by the
r → 1.727 MeV transition. The probable value Jr
π = 3/2-
for the r → 0 MeV transition can lead to the M2-
strength of 19.2 W.u., that considerably exceeds the
RUL's value. Conclusion: Jr
π = 3/2+
The Ер = 2599 keV resonance. The r → 0 and
r → 1.727 MeV angular distributions together allow
only J = 3/2 for the resonance spin. The value Jr
π = 3/2-
should be eliminated, sins in this case for the r → 0
MeV transition the magnitude of B(M2) = 18.6 W.u. is
significant more than the RUL's value. Conclusion: Jr
π = 3/2+.
The Ер = 2659 keV resonance. The measured angu-
lar distributions of the primary γ-transitions to the g.s.,
3086 and 3707 keV levels show that the spin J = 1/2 can
be excluded, but allow J = 3/2 and 5/2. Only the
r → 1727 keV transition limits the resonance spin to
3/2. The probable value Jr
π = 3/2- for the resonance at
the Ер = 2659 keV resonance can lead to B(M2) = 24.1
W.u. for the r → 1.727 MeV transition, that consider-
ably exceeds the RUL's value. Conclusion: Jr
π = 3/2+.
Table 2. Results of the angular distributions for the dominant primary transitions
E
p
, keV
**
fi EE → , MeV ππ
fi JJ → b(γ), % a
2
± ∆a
2
a
4
± ∆a
4
δ ± ∆δ
2539 10.857→ 0
→1.727
3/2
+
→ 3/2
+
5/2 → 3/2
+
3/2
+
→ 1/2
+
67
33
0.40±0.08
-0.40±0.15
0.03±0.08
-0.09±0.15
-1.6±0.3
-0.8±0.1
0.20±0.13 or 1.2±0.4
2599 10.915→ 0
→1.727
3/2
+
→ 3/2
+
3/2
+
→ 1/2
+
54
46
0.61±0.08
-0.33±0.08
-0.01±0.06
0.07±0.07
-0.8±0.6
0.10±0.06 or 1.4±0.4
2659 10.973→ 0
→1.727
→3.086
→3.707
3/2
+
→ 3/2
+
5/2 → 3/2
+
3/2
+
→ 1/2
+
3/2
+
→ 5/2
+
5/2 → 5/2
+
3/2
+
→ 3/2
+
5/2 → 3/2
+
55
13
17
15
-0.27±0.05
-0.47±0.16
0.09±0.15
0.36±0.21
-0.06±0.05
0.01±0.14
0.00±0.17
-0.02±0.23
1.3±0.1
0.2±0.05
1.3±0.1
0.4±0.3 or 1.7±0.4
0.1±0.2
-0.19±0.02
-0.65±0.27
2676 10.990→ 0 5/2
+
→ 3/2
+
100 -0.42±0.02 -0.00±0.02 0.44±0.05
The Ер = 2676 keV resonance. The 2χ value for the
r → 0 MeV angular distribution allows only J = 5/2.
The spins J = 1/2 and 3/2 were rejected because the
minimum 2χ exceed the 0.1% confidence limit. Assum-
ing that Jr
π = 5/2- for this resonance, in this case the val-
ue B(M2) = 7.5 W.u., that is more than the RUL's value.
Conclusion: Jr
π = 5/2+.
4.2. SEARCHING ANALOGUE STATE
The identification of analogue states in the (p,γ) re-
action requires prior knowledge of the proton width Гр,
the Coulomb displacement energy ∆ЕC, spins and pari-
ties and the spacing between strong resonances in the
yield curve. Simple calculations based on the Coulomb
displacement energy lead to the conclusion that the ana-
logue of the 0.646 MeV (Jπ = 3/2-) state of the parent
32
nucleus 37S should lie at E* ≈ 10.9 MeV (Ер ≈ 2.6 MeV)
in 37Cl.
The results, obtained in the present work, show, that
among the investigated resonance levels of 37Cl there is
no state, which can be considered as a 2p3/2 state. More-
over, at decays of researched resonances an intensive
M1-transition on an antianalog level (states with
4.176 MeV), expected from accounts on the shell model
[7] with the surface δ-interaction was not observed.
REFERENCES
1. A.A. Koval at al. Resonances in the 36S(р,γ)
37Cl reaction // Izv. Akad. Nauk USSR, Ser. Fiz.
1966, v. 30, p. 1213 - 1217 (in Russian).
2. G.J.L. Nooren and C. Van der Leun. The re-
action 36S(p,γ)37Cl // Nucl. Phys. A. 1984, v. 423,
p. 197-227.
3. A.K. Hyder Jr. and G.I. Harris. An isobaric
analog state with 1f7/2 configuration in 37Cl // Phys.
Let. B, 1967, v. 24, p. 273 - 276.
4. A.N. Vodin, A.S. Kachan and V.M. Mis-
chenko. 1f7/2 analogue resonances in odd nuclei of
the 1d2s shell // Izv. Russian Akad. Nauk, Ser. Fiz.
2002, v. 66, p. 40 - 47 (in Russian).
5. A. Anttila et al. Use of the 27Al(р,γ)28Si,
Ep = 992 keV resonance as a γ-ray intensity stan-
dard // NIM, 1977, v. 147, p. 501 - 505.
6. P.M. Endt and C. Van der Leun. Energy lev-
els of nuclei A < 44 // Nucl. Phys. A, 1990, v. 521,
p. 1 - 873.
7. S. Maripuu. Shell model calculation of M1
probabilities from isobaric analogue states // Nucl.
Phys. A, 1969. v. 123. p. 357 - 364.
33
REFERENCES
|
| id | nasplib_isofts_kiev_ua-123456789-80108 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-11-29T03:09:21Z |
| publishDate | 2002 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Vodin, A.N. Ushakov, I.V. Kachan, A.S. Korda, L.P. Mischenko, V.M. Nemashkalo, B.A. 2015-04-11T19:38:40Z 2015-04-11T19:38:40Z 2002 Searching the analogue 2p₃/₂-resonance in the ³⁶S(p,γ)³⁷Cl reaction / A.N. Vodin, I.V. Ushakov, A.S. Kachan, L.P. Korda, V.M. Mischenko, B.A. Nemashkalo // Вопросы атомной науки и техники. — 2002. — № 2. — С. 30-32. — Бібліогр.: 7 назв. — англ. 1562-6016 PACS: 25.40. Lw, 23.20.-g, 23.20. En, 23.20. Gq, 23.20. Js, 23.20. Lv https://nasplib.isofts.kiev.ua/handle/123456789/80108 Searching the analogue 2p₃/₂-resonance in ³⁷Cl, which is an isobaric analogue of the parent level with E* = 0.646 MeV (Jp = 3/2-) of ³⁷S was carried out. The excitation function for the ³⁶S(p,g)³⁷Cl reaction was measured in the energy region Ep = 2487 - 2680 keV. Resonance strengths were determined for 44 resonances. The decay schemes and branching ratios of four resonances were investigated at Ep = 2539, 2599, 2659 and 2676 keV. Spins and parities of these resonances (3/2⁺, 3/2⁺, 3/2⁺ and 5/2⁺, correspondingly) were established from angular distributions of γ-rays and measured intensities of γ-transitions. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Nuclear reactions Searching the analogue 2p₃/₂-resonance in the ³⁶S(p,γ)³⁷Cl reaction Searching the analogue 2p₃/₂-resonance in the ³⁶S(p,γ)³⁷Cl reaction Поиск аналогового 2p₃/₂-резонанса в реакции ³⁶S(p,γ)³⁷Cl Article published earlier |
| spellingShingle | Searching the analogue 2p₃/₂-resonance in the ³⁶S(p,γ)³⁷Cl reaction Vodin, A.N. Ushakov, I.V. Kachan, A.S. Korda, L.P. Mischenko, V.M. Nemashkalo, B.A. Nuclear reactions Searching the analogue 2p₃/₂-resonance in the ³⁶S(p,γ)³⁷Cl reaction |
| title | Searching the analogue 2p₃/₂-resonance in the ³⁶S(p,γ)³⁷Cl reaction |
| title_alt | Поиск аналогового 2p₃/₂-резонанса в реакции ³⁶S(p,γ)³⁷Cl |
| title_full | Searching the analogue 2p₃/₂-resonance in the ³⁶S(p,γ)³⁷Cl reaction |
| title_fullStr | Searching the analogue 2p₃/₂-resonance in the ³⁶S(p,γ)³⁷Cl reaction |
| title_full_unstemmed | Searching the analogue 2p₃/₂-resonance in the ³⁶S(p,γ)³⁷Cl reaction |
| title_short | Searching the analogue 2p₃/₂-resonance in the ³⁶S(p,γ)³⁷Cl reaction |
| title_sort | searching the analogue 2p₃/₂-resonance in the ³⁶s(p,γ)³⁷cl reaction |
| topic | Nuclear reactions Searching the analogue 2p₃/₂-resonance in the ³⁶S(p,γ)³⁷Cl reaction |
| topic_facet | Nuclear reactions Searching the analogue 2p₃/₂-resonance in the ³⁶S(p,γ)³⁷Cl reaction |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/80108 |
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