Influence of short-range correlations on ⁴He(e,e')X reaction cross section
Inelastic electron scattering on 4He nucleus is considered in the energy and momentum transfer region related with the quasifree and pion electroproduction peaks. Comparisons are shown between the data and models based on a quasifree reaction mechanism. The dynamic short-range correlation contributi...
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| Опубліковано в: : | Вопросы атомной науки и техники |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2000
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| Цитувати: | Influence of short-range correlations on ⁴He(e,e')X reaction cross section / E.L. Kuplennikov // Вопросы атомной науки и техники. — 2000. — № 2. — С. 7-8. — Бібліогр.: 7 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859622439315570688 |
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| author | Kuplennikov, E.L. |
| author_facet | Kuplennikov, E.L. |
| citation_txt | Influence of short-range correlations on ⁴He(e,e')X reaction cross section / E.L. Kuplennikov // Вопросы атомной науки и техники. — 2000. — № 2. — С. 7-8. — Бібліогр.: 7 назв. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| description | Inelastic electron scattering on 4He nucleus is considered in the energy and momentum transfer region related with the quasifree and pion electroproduction peaks. Comparisons are shown between the data and models based on a quasifree reaction mechanism. The dynamic short-range correlation contribution is found to be significant in this kinematical region.
|
| first_indexed | 2025-11-29T06:39:19Z |
| format | Article |
| fulltext |
INFLUENCE OF SHORT-RANGE CORRELATIONS
ON 4He(e,e′)X REACTION CROSS SECTION
E.L. Kuplennikov
National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
Inelastic electron scattering on 4He nucleus is considered in the energy and momentum transfer region related
with the quasifree and pion electroproduction peaks. Comparisons are shown between the data and models based on
a quasifree reaction mechanism. The dynamic short-range correlation contribution is found to be significant in this
kinematical region.
PACS 25.30.Fj
1. INTRODUCTION
It is known that the NN-interaction has a strongly re-
pulsive core. It is natural to expect that when two nucle-
ons come within a distance of the order of the core ra-
dius (about 0.5 fm), they get accelerated. As a result, the
nucleon momentum in nuclei (p) can be larger than the
Fermi limit (pF). Theoretical calculations confirmed that
taking into consideration strongly repulsive forces oc-
curring at short distances (dynamic Short Range Corre-
lations (SRC)) leads to qualitative modifications of the
results obtained in the independent particle model [1].
The nucleon momentum distribution ρ(р) at large mo-
menta p>pF is determined by pair and many-particle cor-
relations.
Putting some assumptions, the double differential
cross section of the inclusive (e,e’) electron scattering in
the quasifree peak (QFP) region (region, where nucleons
are directly ejected from the nucleus without passing
through quasi-bound states) is proportional to the inte-
gral of ρ(р) [2]. So, SRC effects can be investigated in
the inelastic electron scattering on nuclei under such
kinematical conditions that the high-momentum compo-
nent of ρ(р) manifests itself in a maximum way. These
kinematical conditions are known. For large transfered
momenta the QFP cross section at high- ω»ωpeak and
low- ω«ωpeak energy loss is determined by the high mo-
mentum component of ρ(р).
Note, that SRC modify the energy spectra not only in
the QFP “tails” at large or small energy loss. They can
influence on a QFP cross section and its position [2,3].
Investigations have shown, that the QFP position is in
considerable extent determined by the Jastrow correla-
tion factor that is used in calculations. Besides, due to
SRC the inclusive electron scattering can be accompa-
nied by ejection of deuterons and NN- pairs from the nu-
clear-target [4]. This two-body emission via the direct
correlation mechanism modifies the experimental cross
section both in the QFP maximum and in the intermedi-
ate so-called dip-region (region between QFP and ∆
(1232) resonance).
This paper reports the results of measurements of in-
elastic scattering at 20 and 300 of 1.169 GeV incident
electrons from 4He target in the QFP and first nucleon
resonance region. Systematic features of the continuum
scattering data are compared with calculations that use
realistic NN-interaction. The influence of final state in-
teraction (FSI) of the ejected nucleon with the residual
nucleus and SRC on the QFP cross section is discussed.
2. EXPERIMENTAL PROCIDURE
The double differential cross section of the
4He(e,e’)X reaction are presented in figs. 1 and 2. The
energy spectra of inelastic electron scattering were taken
at the Kharkov linear accelerator LA-2 GeV. (incident
electron energy 1.169 GeV, scattering angles 20 и 300).
Measurements have been performed on low- tempera-
ture 4He target over a wide energy loss region 0≤ω≤
0,75 GeV and overlapped quasi-free and pion electro-
production peaks. Scattered electrons were analyzed on
their momenta with a double-focusing magnetic spec-
trometer and detected with a telescope of counters. The
telescope consisted of two many-wire proportional
chambers with momentum acceptance 0,14% per chan-
nel, a shower total-absorption detector and a Cherenkov
threshold gas counter. To increase the statistical accura-
cy in the condition of small cross sections every experi-
mental point was obtained by averaging the number of
counts in the 5 МeV interval. The radiative corrections
to the cross sections were introduced by the standard
method [5]. The error bars include statistical errors only.
0,0 0,2 0,4 0,6 0,8
0
10
20
30
40
50
60
2
1
3
d2 σ
/d
ω
dΩ
, µ
b
/G
eV
s
r
ω , GeV
Fig. 1. Inclusive differential cross sections for 4Не
as a function of energy loss. The data were taken at a
spectrometer angle 200 with beam energy of 1.169 GeV.
Curves 1-3 are described in the text.
3. RESULTS AND DISCUSSION
In Figs. 1 and 2 the experimental energy spectra of
the 4Не(е,е’)X reaction and results of modern theoretical
calculations, which take into account pair and more
complex short-range correlations between nucleons, are
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2000, №2.
Серия: Ядерно-физические исследования (36), с. 7-8.
7
given. Curves 1 and 2 in Fig. 1 represent the counts in
the frame of theoretical approach [6] for the realistic Ur-
bana potential with and without s- pole respectively. s-
pole reflects the most significant part of FSI. In this ap-
proach main attention is paid to the covariance, conser-
vation of electromagnetic current and taking into ac-
count the structure of the 4He nucleus. The approxima-
tion [6] takes into account SRC.
Curve 3 is a prediction of the harmonic oscillator
model (HOM). The oscillator parameter Р0=130 МeV/с
was obtained from the 4Не root-mean-square radius
measured in the elastic electron scattering experiment.
The parameter takes into account a correction of the
center-of-mass motion. The separation energy was
19.8 MeV. It is seen from Fig. 1, that curves 1-3 differ
between themselves in the QFP maximum. A reasonable
agreement with experimental points takes place only for
HOM calculations.
Calculations in the framework of approximation [6]
for the realistic Urbana potential do not give reasonable
agreement in the QFP maximum. At the same time, the
calculations demonstrate the important role of the FSI.
The absolute value of the QFP cross section, its width
and position are changed. The calculated peak is some
narrower then experimental one and is shifted relatively
to experimental points and HOM calculations to the side
of a high-energy loss. The contribution of the final N-
nucleus interaction increases with momentum transfer
decrease (compare Figs. 1 and 2).
0,00 0,25 0,50 0,75
0,01
0,1
1
1
3
21
d2 σ
/d
Ω
dω
, µ
b
/
G
e
V
s
r
ω , GeV
Fig. 2. Inclusive differential cross section for 4Не as
a function of energy loss. The data were taken at a
spectrometer angle 300 with beam energy of 1.169 GeV.
Curves 1-3 are described in the text.
The curves 1 and 2 in Fig. 2 are the results of calcu-
lations in the frame of HOM and approach [6] for Ur-
bana potential respectively. In the latter version curves
with and without s- pole coincide, that is for given kine-
matical conditions influence of the final N-nucleus inter-
action is negligible. Curve 3 – counts with nucleon mo-
mentum distribution, which was obtained by the varia-
tional method ATMS [7] for Reid Soft Core potential.
The curve 3 is calculated within the ATMS and Y1 ap-
proximation with relativistic kinematics for the recoil
nucleon [2].
It can be seen from fig. 2 that nuclear models, which
take into account the pair and more complex SRC, give
rather good description of the QFP maximum. At the
same time, account with the ATMS nucleon momentum
distribution and theoretical approximation [6] predicts a
significant difference at the high energy loss side ω»ωpeak
of the QFP between themselves and relatively to HOM
calculations.
Taking into account SRC increases the cross section
and improves the agreement with the experiment at high
energy loss. But the contribution of high momentum
component into the total cross section is small. Its value
is not sufficient to get agreement in the dip-region. The
АТМS nucleon momentum distribution predicts the
highest value of the cross section in this kinematical re-
gion. Even in the electroproduction peak maximum con-
tribution of the ATMS calculations into the total one is
small but not negligible. It consists approximately 4%.
As regards low energy loss side ω«ωpeak of the QFP,
none of the above used theoretical approaches gives rea-
sonable agreement with experimental points. There is
the substantial excess of the experimental cross section
compared to all theoretical calculations.
4. CONCLUSIONS
The inelastic cross section from 4He have been mea-
sured in the QFP and delta-resonance region at E1=1.169
MeV and θ=20 and 300. Comparison of the cross section
was made with calculations that use realistic NN-inter-
actions. It was shown that no theoretical calculation,
which uses SRC effects is able to reproduce the data at
high- and low-energy loss side of the QFP.
REFERENCES
1. Jibuti, R.Y. Kezerashvili. Effects of Short-Range
Correlations and Distortion in the Reaction
4He(e,e’p) 3H // Phys. Lett. 1975, v. B57, p. 433.
2. S.V. Dementij, A.Y. Korchin, E.L. Kuplennikov et
al. Nucleon-Nucleon Correlations and Inelastic Elec-
tron Scattering on 4Не // Journal of the Phys. Soc. of
Japan. 1988, v. 57, p. 2988.
3. E.L. Kuplennikov, A.Yu. Korchin, A.A. Nemashkalo
et al. Studying the quasifree peak maximum shift in
the 4Не(е,е')Х reaction // Yadern. Fiz. 1990, v. 51,
p. 1210 (in Russian).
4. S.I. Nagorny, E.L. Kuplennikov, E.V. Inopin. Deep-
inelastic electron scattering on light nuclei in the in-
termediate energy range // Yadern. Fiz. 1983, v. 38,
p. 345 (in Russian).
5. L.W. Mo, Y.S. Tsai. Radiative corrections to elastic
and inelastic ep and mp scattering // Rev. Mod. Phys.
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6. A.A. Zayats, V.A. Zolenko, Y.A. Kasatkin et al.
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Yadern Fiz. 1992, v. 5, p. 325 (in Russian).
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8
E.L. Kuplennikov
National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
1. INTRODUCTION
2. EXPERIMENTAL PROCIDURE
3. RESULTS AND DISCUSSION
|
| id | nasplib_isofts_kiev_ua-123456789-81729 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-11-29T06:39:19Z |
| publishDate | 2000 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Kuplennikov, E.L. 2015-05-20T09:30:17Z 2015-05-20T09:30:17Z 2000 Influence of short-range correlations on ⁴He(e,e')X reaction cross section / E.L. Kuplennikov // Вопросы атомной науки и техники. — 2000. — № 2. — С. 7-8. — Бібліогр.: 7 назв. — англ. 1562-6016 PACS 25.30.Fj https://nasplib.isofts.kiev.ua/handle/123456789/81729 Inelastic electron scattering on 4He nucleus is considered in the energy and momentum transfer region related with the quasifree and pion electroproduction peaks. Comparisons are shown between the data and models based on a quasifree reaction mechanism. The dynamic short-range correlation contribution is found to be significant in this kinematical region. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Nuclear reactions Influence of short-range correlations on ⁴He(e,e')X reaction cross section Влияние короткодействующих корреляций на сечение реакции 4He(e,e')X Article published earlier |
| spellingShingle | Influence of short-range correlations on ⁴He(e,e')X reaction cross section Kuplennikov, E.L. Nuclear reactions |
| title | Influence of short-range correlations on ⁴He(e,e')X reaction cross section |
| title_alt | Влияние короткодействующих корреляций на сечение реакции 4He(e,e')X |
| title_full | Influence of short-range correlations on ⁴He(e,e')X reaction cross section |
| title_fullStr | Influence of short-range correlations on ⁴He(e,e')X reaction cross section |
| title_full_unstemmed | Influence of short-range correlations on ⁴He(e,e')X reaction cross section |
| title_short | Influence of short-range correlations on ⁴He(e,e')X reaction cross section |
| title_sort | influence of short-range correlations on ⁴he(e,e')x reaction cross section |
| topic | Nuclear reactions |
| topic_facet | Nuclear reactions |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/81729 |
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