The isolated resonance method for investigating orientation effects and electron energy losses of hyperchanneled particles
The isolated resonance of the nuclear reaction on impurity interstitials was used to investigate orientation effects. The method is shown to provide the best energy resolution in comparison with other methods. The ¹³C(p,γ) ¹⁴N reaction resonance at a proton energy of 1.7476 MeV was used to inves...
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nasplib_isofts_kiev_ua-123456789-812232025-02-09T16:40:06Z The isolated resonance method for investigating orientation effects and electron energy losses of hyperchanneled particles Метод ізольованого резонансу та електронні гальмові втрати енергії гіперканальованих частинок Метод изолированного резонанса и электронные тормозные потери энергии гиперканалированных частиц Shershnev, V.M. Skakun, N.A. Ядерная физика и элементарные частицы The isolated resonance of the nuclear reaction on impurity interstitials was used to investigate orientation effects. The method is shown to provide the best energy resolution in comparison with other methods. The ¹³C(p,γ) ¹⁴N reaction resonance at a proton energy of 1.7476 MeV was used to investigate the proton flux distribution in the (0001) plane channel of the single-crystal solution Re-0.4 at.%¹³C. Some special features of the γ-quantum yield of the reaction in relation to energy have been established. Electron energy losses of hyperchanneled protons were measured. It is demonstrated that the γ-quantum yield of the channeled proton-excited reaction is dependent on the amplitude of thermal vibrations of carbon atoms. Ізольований резонанс ядерної реакції на впроваджених атомах домішок використано для вивчення орієнтаційних ефектів. Показано, що цей метод дозволяє одержати краще енергетичне розрізнення у порів- нянні з іншими методами. Резонанс реакції ¹³C(p,γ) ¹⁴N, при енергії протонів 1,7476 МеВ, використовувався для дослідження розподілу потоку протонів у площинному каналі (0001) монокристалічного розчину Re- 0,4 ат.%¹³С. Встановлено особливості виходу γ-квантів реакції в залежності від енергії. Виміряно електронні втрати енергії гіперканальованих протонів. Показано, що вихід γ-квантів реакції, що збуджується канальованими протонами, залежить від амплітуди теплових коливань атомів вуглецю. Изолированный резонанс ядерной реакции на примесных атомах внедрения использован для изучения ориентационных эффектов. Показано, что этот метод позволяет получить лучшее энергетическое разрешение по сравнению с другими методами. Резонанс реакции ¹³C(p,γ) ¹⁴N, при энергии протонов 1,7476 МэВ, использовался для исследования распределения потока протонов в плоскостном канале (0001) монокристаллического раствора Re-0,4 ат.%¹³С. Установлены особенности выхода γ-квантов реакции в зависимости от энергии. Измерены электронные потери энергии гиперканалированных протонов. Показано, что выход γ- квантов реакции, возбуждаемой каналированными протонами, зависит от амплитуды тепловых колебаний атомов углерода. The work was done with partial support of Project X866 ЯMРT 2010. 2005 Article The isolated resonance method for investigating orientation effects and electron energy losses of hyperchanneled particles / V.M. Shershnev, N.A. Skakun // Вопросы атомной науки и техники. — 2005. — № 6. — С. 37-39. — Бібліогр.: 5 назв. — англ. 1562-6016 PACS: 24.30.-v, 68.35.Dv, 68.35.Ln, 61.72.Ji https://nasplib.isofts.kiev.ua/handle/123456789/81223 en Вопросы атомной науки и техники application/pdf Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine |
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| language |
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| topic |
Ядерная физика и элементарные частицы Ядерная физика и элементарные частицы |
| spellingShingle |
Ядерная физика и элементарные частицы Ядерная физика и элементарные частицы Shershnev, V.M. Skakun, N.A. The isolated resonance method for investigating orientation effects and electron energy losses of hyperchanneled particles Вопросы атомной науки и техники |
| description |
The isolated resonance of the nuclear reaction on impurity interstitials was used to investigate orientation effects.
The method is shown to provide the best energy resolution in comparison with other methods. The ¹³C(p,γ)
¹⁴N reaction resonance at a proton energy of 1.7476 MeV was used to investigate the proton flux distribution in the
(0001) plane channel of the single-crystal solution Re-0.4 at.%¹³C. Some special features of the γ-quantum yield of
the reaction in relation to energy have been established. Electron energy losses of hyperchanneled protons were
measured. It is demonstrated that the γ-quantum yield of the channeled proton-excited reaction is dependent on the
amplitude of thermal vibrations of carbon atoms. |
| format |
Article |
| author |
Shershnev, V.M. Skakun, N.A. |
| author_facet |
Shershnev, V.M. Skakun, N.A. |
| author_sort |
Shershnev, V.M. |
| title |
The isolated resonance method for investigating orientation effects and electron energy losses of hyperchanneled particles |
| title_short |
The isolated resonance method for investigating orientation effects and electron energy losses of hyperchanneled particles |
| title_full |
The isolated resonance method for investigating orientation effects and electron energy losses of hyperchanneled particles |
| title_fullStr |
The isolated resonance method for investigating orientation effects and electron energy losses of hyperchanneled particles |
| title_full_unstemmed |
The isolated resonance method for investigating orientation effects and electron energy losses of hyperchanneled particles |
| title_sort |
isolated resonance method for investigating orientation effects and electron energy losses of hyperchanneled particles |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| publishDate |
2005 |
| topic_facet |
Ядерная физика и элементарные частицы |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/81223 |
| citation_txt |
The isolated resonance method for investigating orientation effects and electron energy losses of hyperchanneled particles / V.M. Shershnev, N.A. Skakun // Вопросы атомной науки и техники. — 2005. — № 6. — С. 37-39. — Бібліогр.: 5 назв. — англ. |
| series |
Вопросы атомной науки и техники |
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2025-11-28T01:57:35Z |
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| fulltext |
THE ISOLATED RESONANCE METHOD FOR INVESTIGATING
ORIENTATION EFFECTS AND ELECTRON ENERGY LOSSES OF
HYPERCHANNELED PARTICLES
V.M. Shershnev, N.A. Skakun
National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
e-mail: skakun@kipt.kharkov.ua
The isolated resonance of the nuclear reaction on impurity interstitials was used to investigate orientation effects.
The method is shown to provide the best energy resolution in comparison with other methods. The 13C(p,γ)14N
reaction resonance at a proton energy of 1.7476 MeV was used to investigate the proton flux distribution in the
(0001) plane channel of the single-crystal solution Re-0.4 at.%13C. Some special features of the γ-quantum yield of
the reaction in relation to energy have been established. Electron energy losses of hyperchanneled protons were
measured. It is demonstrated that the γ-quantum yield of the channeled proton-excited reaction is dependent on the
amplitude of thermal vibrations of carbon atoms.
PACS: 24.30.-v, 68.35.Dv, 68.35.Ln, 61.72.Ji
1. INTRODUCTION
The basic facts about orientation effects at
channeling of hydrogen and helium ions were obtained
from the analysis of angular and energy distributions of
particles scattered by the nuclei of crystal atoms [1]. In
the narrow energy range, in the near-surface region of
the crystal, at depths of up to ~ 6 wavelengths of
particle trajectory oscillations, the scattering spectrum
shows a fine structure. Therefore, in studies of a
channeled particle flux in this region, stringent
requirements are imposed on the energy resolution of
the method. The two factors, namely, straggling
(discrete statistical character of electron energy loss
fluctuations in the medium) at the crystal in/out parts of
the scattered particle trajectory and the energy
resolution of the spectrometer, substantially restrict the
experimental possibilities of the scattering method. This
leads to the smoothing of spectra, blurring of their
structure and, as a consequence, to ambiguities in the
analysis of results [2].
To investigate the orientation effects, we offer an
approach based on the use of isolated resonances of
excitation functions of the reactions on the impurity
interstitial and substitution atoms, which occupy certain
positions in the crystal.
2. METHOD
The property of many nuclear reactions is the
presence of one or more peaks (resonances) in the plot
showing the radiation yield (e.g., (p,γ) reaction) versus
particle energy. These resonances are measured
experimentally by varying the energy through its small
increments with simultaneous measurement of the
reaction yield for each energy value. At E0 > Eres, the
particle loses its energy in the target until the energy
attains the resonance value at the depth “x” in the “δx”
element, where the reaction takes place.
If the reaction is excited by channeled particles, the
resonance radiation yield depends not only on the atom
concentration in the “δx”. In this case, the yield is also
dependent on many other factors: the flux distribution in
the channel, the arrangement of atoms, on which the
reaction is excited, electron energy losses of channeled
particles, the energy straggling, the crystallographic
direction, etc.
The resolution of the elastic scattering method,
without regard for both the geometry responsible for the
solid acceptance angle of the detector and the target
surface roughness, is given by the expression
( ) ( ) ( ) ( ) ( ) 22222
outinspcbmbs EEEEE δδδδ +++=∆ , (1)
where δEbm is the beam energy straggling at entry into
the crystal, δEspc is the spectrometer resolution, δEin,
δEout denote the straggling before and after particle
scattering in the target, respectively.
0 2 4 6 8 10
0
1
2
3
4
5
6
7
8
9
10
∆
E
(k
eV
)
Energy losses (keV)
Fig. 1. Energy resolution of the backscattering
method as a function of energy losses for the surface-
barrier detector (), magnetic spectrometer (), and the
method of resonant nuclear reaction 15N(p,αγ)12C ()
Fig. 1 shows the resolving power of scattering
methods versus energy losses, as ~ 0.5 MeV protons
penetrate deep into the target. The straggling depends
PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY. 2005, № 6.
Series: Nuclear Physics Investigations (45), p. 37-39. 37
on the depth, at which the particle is scattered in the
crystal. As it is seen from Fig. 1, in the parts of the
proton trajectory before δEin and after δEout scattering in
the near-surface zone of the crystal the contribution to
the resolving power from straggling is insignificant if a
semiconductor-detector spectrometer is used. The
measurements of scattered proton energy with the use of
a cooled Si - detector (curve ( )) give the worst
resolution. This is due to the fact that the
semiconductor-detector spectrometer for the protons of
this energy has δEspc ~ 9 keV [3]. The use of the
magnetic analyzer for the spectrometry of scattered
particles [4], as it follows from Fig. 1 ( ), substantially
improves the energy resolution. Here the straggling does
give a certain contribution to the energy resolution. But
in the given case, the magnetic analyzer acts as a
differential instrument; besides, its scattered-particle
acceptance solid angle is considerably smaller than that
of the semiconductor-detector spectrometer.
The dependence of the resolving power of the
isolated resonance method on the depth, at which the
reaction occurs, is defined by the expression
( ) ( ) ( ) ( ) 22222
inDresbmnr EEΓEE δδδ +++=∆ , (2)
where δEbm is the beam energy straggling at entry into
the crystal, Γres is the natural line width of resonance,
δED is the Doppler broadening the natural line with Γres
of the resonance, δEin is the energy straggling of
particles at entry into the crystal. The resonance can be
selected to have Γres > δED.
As it follows from Eq. (1), the resolution depends on
channeled particle straggling over the part of the
trajectory up to the reaction excitation, and is
independent of the spectrometer resolution. This enables
one to obtain a much better depth resolution by the
isolated resonance method rather than by the scattering
method.
The two methods are equally dependent on δEbm.
Stringent requirements are imposed on the technical
capabilities of the accelerator.
3. RESULTS AND DISCUSSION
The program developed to simulate the channeled
particle flux as well as the experimental data on the
location of carbon atoms in the single-crystal solution
Re-0.4 at.%13C were used to investigate the evolution of
proton trajectories in the plane channel (0001) by the
isolated resonance method. The nuclear reaction
13C(p,γ)14N, which shows a strong isolated resonance at
a proton energy of 1.7476 MeV, Γres = 135 eV, was used
to determine the localization of carbon atoms. It has
been established [5] that carbon in rhenium occupies
octahedral interstitial sites. In crystals with the
hexagonal close-packed lattice (rhenium being among
them), the plane of octahedral interstitial sites lies just at
the center between the (0001) planes.
0,5 1,0 1,5 2,0
0
2
4
6
8
250
200
150
100
50
Plane distance (Å)
N
or
m
al
iz
ed
f
la
x
D ep th (
Å )
Fig. 2. Channeled proton flux distribution in the transverse plane along the (0001) channel, E0 = 1.7476 MeV, φin = 0˚
Fig. 2 shows some special features of the dynamic
distribution of the proton flux in the (0001) channel up
to the first bundle of trajectories for a variety of depth
values. As a result of a series of soft correlated
collisions with the atoms of the planes, protons having a
large amplitude of trajectories give rise to the peaks
along the edges of the flux distribution. As the depth
grows, the peaks approach the center of the channel and
form the maximum in the region of the first bundle of
trajectories. As it is obvious from Fig. 1, in the middle
of the channel, up to the maximum, the flux of
hyperchanneled protons is uniform in the transverse
plane, and is close to a constant value, irrespective of
the depth value.
Fig. 3 shows the calculated (, - - -) and measured
( ) functions of the 13C(p,γ)14N reaction excitation at
proton channeling along the (0001) plane up to the first
bundle of trajectories. The same figure shows the
excitation function for random protons (ÿ ). As
38
expected, a sharp increase in the γ-quantum yield is
1747,5 1748,0 1748,5 1749,0 1749,5 1750,0
0
200
400
600
800
1000
1200
1400
1600
1800
2000
Y
ie
ld
Energy (keV)
↓
Fig. 3. 13C(p,γ)14N reaction yield vs proton energy
observed at the resonance energy, irrespective of the
beam momentum orientation relative to the crystal. The
increase in the reaction yield for random protons attains
saturation and further remains unchanged irrespective of
energy. The excitation function for channeled protons
has a plateau, ~ 400 eV in width (shown by the arrow in
the figure). The γ-quantum yield in this region stays
close to a constant value, and substantially exceeds the
yield from random protons. The hyperchanneled proton
flux at the center of the channel, where valence
electrons are found (Fig. 1), gives the main contribution
to the reaction excitation function in the plateau part. An
insignificant contribution to the excitation function
comes from dechanneled protons. The increased yield
observed in the plateau region as compared to the yield
for random protons is accounted for by a decrease in the
electron energy losses of hyperchanneled protons on
valence electrons. The estimates give the ratio
(dE/dx)(0001) / (dE/dx)random to be 0.64. The greatest γ-
quantum yield is realized in the region of the first
bundle of proton trajectories.
The simulation program used here takes into account
the thermal vibrations of impurity atoms in the
transverse plane of the (0001) channel in the harmonic
approximation. Numerical calculations have pointed
(Fig. 3) to the existing dependence of the reaction yield
at the maximum of the excitation function on the r.m.s.
amplitude of thermal vibrations of 13C atoms. As the
amplitude of 13C vibrations grows the γ-quantum yield
drops. The best agreement between the measured data
and the calculations was obtained at the thermal
vibration amplitude equal to 0.102 Å.
The work was done with partial support of Project
X866 ЯMРT 2010.
REFERENCES
1. D.S. Gemmell. Channeling and Related Effects in
the Motion of Charged Particles Through Crystals //
Rev. Mod. Phys. 1974, v. 46, №1, p. 129-227.
2. John H Barrett. Potential and stopping – power
information from planar – channeling oscillations //
Phys. Rev. 1989, v. 20, №9, p. 3535-3542.
3. F. Abel, G. Amsel, M. Bruneaux, et al.
Backscattering study and theoretical investigation of
planar channeling processes // Phys. Rev. B. 1975,
v. 12, №11 p. 4617-4627.
4. E. Bogh. An application of high energy-resolution
scattering measurements in channeling studies //
Radiation effects. 1972, v. 12, p. 13-19.
5. N.A. Skakun, V.A. Olejnik et al. Channeling study
of carbon atom location in Re – Cx system // Nucl.
Instr. Meth. B. 1992, v. 67, p. 199-202.
МЕТОД ИЗОЛИРОВАННОГО РЕЗОНАНСА
И ЭЛЕКТРОННЫЕ ТОРМОЗНЫЕ ПОТЕРИ ЭНЕРГИИ ГИПЕРКАНАЛИРОВАННЫХ ЧАСТИЦ
В.М. Шершнев, Н.А. Скакун
Изолированный резонанс ядерной реакции на примесных атомах внедрения использован для изучения
ориентационных эффектов. Показано, что этот метод позволяет получить лучшее энергетическое разреше-
ние по сравнению с другими методами. Резонанс реакции 13C(p,γ)14N, при энергии протонов 1,7476 МэВ,
использовался для исследования распределения потока протонов в плоскостном канале (0001) монокристал-
лического раствора Re-0,4 ат.%13С. Установлены особенности выхода γ-квантов реакции в зависимости от
энергии. Измерены электронные потери энергии гиперканалированных протонов. Показано, что выход γ-
квантов реакции, возбуждаемой каналированными протонами, зависит от амплитуды тепловых колебаний
атомов углерода.
МЕТОД ІЗОЛЬОВАНОГО РЕЗОНАНСУ
ТА ЕЛЕКТРОННІ ГАЛЬМОВІ ВТРАТИ ЕНЕРГІЇ ГІПЕРКАНАЛЬОВАНИХ ЧАСТИНОК
В.М. Шершнєв, М.О. Скакун
Ізольований резонанс ядерної реакції на впроваджених атомах домішок використано для вивчення
орієнтаційних ефектів. Показано, що цей метод дозволяє одержати краще енергетичне розрізнення у порів-
нянні з іншими методами. Резонанс реакції 13C(p,γ)14N, при енергії протонів 1,7476 МеВ, використовувався
для дослідження розподілу потоку протонів у площинному каналі (0001) монокристалічного розчину Re-
0,4 ат.%13С. Встановлено особливості виходу γ-квантів реакції в залежності від енергії. Виміряно електронні
втрати енергії гіперканальованих протонів. Показано, що вихід γ-квантів реакції, що збуджується
канальованими протонами, залежить від амплітуди теплових коливань атомів вуглецю.
39
National Science Center “Kharkov Institute of Physics and Technology”, Kharkov, Ukraine
Метод изолированного резонанса
|