Magnetic system for cleaning the gamma beam at the LUE-40 electron linac output
The bremsstrahlung of accelerated electrons passing through a converter is used to study multiparticle photo-nuclear reactions. The results of calculations, numerical modeling, design, and testing of a special magnetic cleaning system to obtain a “pure” beam of bremsstrahlung quanta when studying th...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2022
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| Цитувати: | Magnetic system for cleaning the gamma beam at the LUE-40 electron linac output / V.V. Mytrochenko, S.O. Perezhogin, L.I. Selivanov, V.Ph. Zhyglo, A.N. Vodin, O.S. Deiev, S.M. Olejnik, I.S. Timchenko, V.A. Kushnir // Problems of Atomic Science and Technology. — 2022. — № 3. — С. 62-67. — Бібліогр.: 30 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| id |
nasplib_isofts_kiev_ua-123456789-195393 |
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Mytrochenko, V.V. Perezhogin, S.O. Selivanov, L.I. Zhyglo, V.Ph. Vodin, A.N. Deiev, O.S. Olejnik, S.M. Timchenko, I.S Kushnir, V.A. 2023-12-05T09:45:33Z 2023-12-05T09:45:33Z 2022 Magnetic system for cleaning the gamma beam at the LUE-40 electron linac output / V.V. Mytrochenko, S.O. Perezhogin, L.I. Selivanov, V.Ph. Zhyglo, A.N. Vodin, O.S. Deiev, S.M. Olejnik, I.S. Timchenko, V.A. Kushnir // Problems of Atomic Science and Technology. — 2022. — № 3. — С. 62-67. — Бібліогр.: 30 назв. — англ. 1562-6016 PACS: 41.75.Ht, 25.20.-x, 25.20.-x https://nasplib.isofts.kiev.ua/handle/123456789/195393 The bremsstrahlung of accelerated electrons passing through a converter is used to study multiparticle photo-nuclear reactions. The results of calculations, numerical modeling, design, and testing of a special magnetic cleaning system to obtain a “pure” beam of bremsstrahlung quanta when studying the cross-sections of such reactions at the LUE-40 linac are presented. The system is based on commercially available permanent magnets of rectangular cross-sections. The maximum on-axis field is 0.9 T, which provides sufficient separation of the electron beam and gamma rays at a distance of more than 90 mm from the magnet. Гальмівне випромінювання прискорених електронів, що проходять через конвертер, використовується для дослідження багаточастинкових фотоядерних реакцій. Наведено результати розрахунків чисельного моделювання, проєктування та випробування спеціальної системи магнітного очищення для отримання «чистого» пучка квантів гальмівного випромінювання при дослідженні перерізів таких реакцій на прискорювачі ЛУЕ-40. Система базується на основі наявних у продажу постійних магнітів прямокутного перерізу. Максимальне поле на осі становить 0,9 Тл, що забезпечує достатнє розділення електронного пучка й гамма-променів на відстані більше 90 мм від магніту. Тормозное излучение ускоренных электронов, прошедших конвертер, используется для изучения многочастичных фотоядерных реакций. Представлены результаты расчетов численного моделирования, проектирования и испытаний специальной системы магнитной очистки для получения «чистого» пучка тормозных квантов при исследовании сечений таких реакций на линейном ускорителе ЛУЭ-40. Система базируется на основе серийно выпускаемых постоянных магнитов прямоугольного сечения. Максимальное осевое поле составляет 0,9 Тл, что обеспечивает достаточное разделение электронного пучка и гамма-квантов на расстоянии более 90 мм от магнита. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Theory and technology of particle acceleration Magnetic system for cleaning the gamma beam at the LUE-40 electron linac output Магнітна система для очищення гамма-пучка на вихіді прискорювача електронів ЛУЕ-40 Магнитная система очистки гамма-пучка на выходе ускорителя электронов ЛУЭ-40 Article published earlier |
| institution |
Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| collection |
DSpace DC |
| title |
Magnetic system for cleaning the gamma beam at the LUE-40 electron linac output |
| spellingShingle |
Magnetic system for cleaning the gamma beam at the LUE-40 electron linac output Mytrochenko, V.V. Perezhogin, S.O. Selivanov, L.I. Zhyglo, V.Ph. Vodin, A.N. Deiev, O.S. Olejnik, S.M. Timchenko, I.S Kushnir, V.A. Theory and technology of particle acceleration |
| title_short |
Magnetic system for cleaning the gamma beam at the LUE-40 electron linac output |
| title_full |
Magnetic system for cleaning the gamma beam at the LUE-40 electron linac output |
| title_fullStr |
Magnetic system for cleaning the gamma beam at the LUE-40 electron linac output |
| title_full_unstemmed |
Magnetic system for cleaning the gamma beam at the LUE-40 electron linac output |
| title_sort |
magnetic system for cleaning the gamma beam at the lue-40 electron linac output |
| author |
Mytrochenko, V.V. Perezhogin, S.O. Selivanov, L.I. Zhyglo, V.Ph. Vodin, A.N. Deiev, O.S. Olejnik, S.M. Timchenko, I.S Kushnir, V.A. |
| author_facet |
Mytrochenko, V.V. Perezhogin, S.O. Selivanov, L.I. Zhyglo, V.Ph. Vodin, A.N. Deiev, O.S. Olejnik, S.M. Timchenko, I.S Kushnir, V.A. |
| topic |
Theory and technology of particle acceleration |
| topic_facet |
Theory and technology of particle acceleration |
| publishDate |
2022 |
| language |
English |
| container_title |
Вопросы атомной науки и техники |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| format |
Article |
| title_alt |
Магнітна система для очищення гамма-пучка на вихіді прискорювача електронів ЛУЕ-40 Магнитная система очистки гамма-пучка на выходе ускорителя электронов ЛУЭ-40 |
| description |
The bremsstrahlung of accelerated electrons passing through a converter is used to study multiparticle photo-nuclear reactions. The results of calculations, numerical modeling, design, and testing of a special magnetic cleaning system to obtain a “pure” beam of bremsstrahlung quanta when studying the cross-sections of such reactions at the LUE-40 linac are presented. The system is based on commercially available permanent magnets of rectangular cross-sections. The maximum on-axis field is 0.9 T, which provides sufficient separation of the electron beam and gamma rays at a distance of more than 90 mm from the magnet.
Гальмівне випромінювання прискорених електронів, що проходять через конвертер, використовується для дослідження багаточастинкових фотоядерних реакцій. Наведено результати розрахунків чисельного моделювання, проєктування та випробування спеціальної системи магнітного очищення для отримання «чистого» пучка квантів гальмівного випромінювання при дослідженні перерізів таких реакцій на прискорювачі ЛУЕ-40. Система базується на основі наявних у продажу постійних магнітів прямокутного перерізу. Максимальне поле на осі становить 0,9 Тл, що забезпечує достатнє розділення електронного пучка й гамма-променів на відстані більше 90 мм від магніту.
Тормозное излучение ускоренных электронов, прошедших конвертер, используется для изучения многочастичных фотоядерных реакций. Представлены результаты расчетов численного моделирования, проектирования и испытаний специальной системы магнитной очистки для получения «чистого» пучка тормозных квантов при исследовании сечений таких реакций на линейном ускорителе ЛУЭ-40. Система базируется на основе серийно выпускаемых постоянных магнитов прямоугольного сечения. Максимальное осевое поле составляет 0,9 Тл, что обеспечивает достаточное разделение электронного пучка и гамма-квантов на расстоянии более 90 мм от магнита.
|
| issn |
1562-6016 |
| url |
https://nasplib.isofts.kiev.ua/handle/123456789/195393 |
| citation_txt |
Magnetic system for cleaning the gamma beam at the LUE-40 electron linac output / V.V. Mytrochenko, S.O. Perezhogin, L.I. Selivanov, V.Ph. Zhyglo, A.N. Vodin, O.S. Deiev, S.M. Olejnik, I.S. Timchenko, V.A. Kushnir // Problems of Atomic Science and Technology. — 2022. — № 3. — С. 62-67. — Бібліогр.: 30 назв. — англ. |
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62 ISSN 1562-6016. ВАНТ. 2022. №3(139)
https://doi.org/10.46813/2022-139-062
MAGNETIC SYSTEM FOR CLEANING THE GAMMA BEAM
AT THE LUE-40 ELECTRON LINAC OUTPUT
V.V. Mytrochenko, S.O. Perezhogin, L.I. Selivanov, V.Ph. Zhyglo, A.N. Vodin,
O.S. Deiev, S.M. Olejnik, I.S. Timchenko, V.A. Kushnir
National Science Center “Kharkov Institute of Physics and Technology”, Kharkiv, Ukraine
E-mail: mitvic@kipt.kharkov.ua
The bremsstrahlung of accelerated electrons passing through a converter is used to study multiparticle photo-
nuclear reactions. The results of calculations, numerical modeling, design, and testing of a special magnetic cleaning
system to obtain a “pure” beam of bremsstrahlung quanta when studying the cross-sections of such reactions at the
LUE-40 linac are presented. The system is based on commercially available permanent magnets of rectangular
cross-sections. The maximum on-axis field is 0.9 T, which provides sufficient separation of the electron beam and
gamma rays at a distance of more than 90 mm from the magnet.
PACS: 41.75.Ht, 25.20.-x, 25.20.-x
INTRODUCTION
Cross-sections of the photonuclear reactions were
mainly obtained experimentally in a study of the giant
dipole resonance (GDR) using bremsstrahlung radiation
and quasi monoenergetic photons [1 - 5] at -quanta
energies up to 30 MeV. Recently obtained experimental
results on the cross-sections of multiparticle photo-
nuclear reactions at -quanta energies of 30…145 MeV
are quantitatively many times different from the data on
(,n) reactions.
Study of photofission of nuclei in the energy range
above the GDR through to the threshold of pion produc-
tion (Eth 145 MeV) is of particular interest because
there is a change in the mechanism of interaction of
photons with nuclei in this energy region. Therefore it is
possible to obtain fundamental data on two mechanisms
of photofission of the nucleus, namely, due to GDR
excitation and quasi-deuteron photoabsorption [6]. To
date, various theoretical models, for example, [7, 8], as
well as the modern nuclear reaction codes [9 - 12], have
been developed to describe photonuclear reactions at
their cross-section calculations. Both the theoretical
models and the calculation codes need new data to veri-
fy multiparticle reactions in a wide range of atomic
masses and energies.
In practical applications, knowledge of the exact pa-
rameters of multiparticle photonuclear reactions is im-
portant, for example, to estimate the neutron yield in
nuclear installations based on accelerator-driven subcrit-
ical systems (ADS). The ADS can be used for the utili-
zation of radioactive waste of nuclear energy plants
(transmutation of minor actinides [13] and burning
long-lived fission fragments). The ADS are also poten-
tial sources for electricity generation [14, 15].
The study of multiparticle photonuclear reactions
with relatively small cross-sections (~ 0.1…100 mb) is
possible in the presence of intense fluxes of the incident
-quanta. Such fluxes can be obtained by passing beams
of high-energy electrons through a target converter. Ex-
periments with the use of bremsstrahlung, which has a
continuous spectrum of the form ~ 1/Eγ and the maxi-
mum limiting energy Emax, make it possible to deter-
mine the integral characteristics of the reactions, such as
the averaged yield Y(Еγmax) and average cross-section
σ(Еγmax) of reactions. On the other hand, the applica-
tion of such spectrum complicates the procedure for
determining the (Еγ) cross-sections of photonuclear
reactions because it requires additional calculations and
the use of various data processing methods. In both cas-
es there is a need for correct calculations of the -quanta
flux density, which corresponds to the real conditions of
the experiments, with modern computational codes, for
example, such as GEANT4 [16]. However, despite the
difficulties, bremsstrahlung beams remain an important
tool in nuclear physics research [17 - 19].
In the experiments with bremsstrahlung, three main
schemes can be distinguished. The first one uses a flux
consisting of bremsstrahlung and electrons that have
passed through the converter [17] that interacts with
atoms of the target substance. The advantages of this
method are mainly in the simplicity of the approach,
however high radiation load on the target leads to tech-
nical difficulties (sintering of samples, burning of struc-
tural elements of the target node, etc.). It is also neces-
sary to consider a contribution to the reaction yield from
the processes occurring under the action of electrons.
Usually, this contribution can be calculated, although its
probability is strongly suppressed by the mechanism of
interaction of electrons through virtual photons. The
constant of this interaction is proportional to the con-
stant of fine structure which is about 1/137. However,
for high-threshold reactions, the contribution of elec-
trons may dominate. Thus, it was shown in [20] on the
example of
93
Nb(γ,xn)
93-x
Nb reactions, where x is neu-
tron multiplicity, that for the case of x = 5 the yield of
the reaction under the action of gamma quanta becomes
less than that from the contribution of electrons.
The second scheme is similar to the first one, but af-
ter the converter, a massive electron absorber consisting
of light material (usually Al) [21, 22] is installed. The
advantage of such a scheme is the simplicity and almost
a "pure" gamma quantum beam on the target. This guar-
antees a slight radiation and heat load of the target and,
for example, on the components of the pneumatic tube
transport that is used for target delivery. The disad-
vantages of this scheme are the distortion of the shape
of the bremsstrahlung spectrum, and the additional gen-
eration of photoneutrons, which also contribute to stud-
ied reaction yield.
mailto:mitvic@kipt.kharkov.ua
ISSN 1562-6016. ВАНТ. 2022. №3(139) 63
The third scheme of the experiment implements a
bending magnet to divert the electrons that have passed
through the converter [22] that allows obtaining a
"pure" beam of bremsstrahlung gamma quanta at the
target. When using thin converters, the shape of the ra-
diation spectrum can be described by a known analytical
formula. At the same time, the influence of neutrons is
minimized.
Thus, the study of photonuclear reactions with the
"pure" gamma beam using the third scheme has the fol-
lowing advantages:
• Thin converter can be used because electrons will
not create a radiation load and gamma rays will not scat-
ter in the absorber. Accordingly, the bremsstrahlung
spectrum can be described by an analytical formula of
the form ~ 1/Eγ.
• The contribution of neutrons to the reaction outputs
can be neglected.
• The possibility of using pneumatic tube transport
remains.
• There is the possibility to obtain cross-sections of
photonuclear reactions (Еγ) with the photon difference
method or the regularization method.
• Due to the lack of the absorber, it is possible to
significantly decrease the volume of calculations of
bremsstrahlung gamma flux with the computer codes.
Experimental and calculated errors are significantly
reduced.
All the above mentioned makes the task of obtaining
a "pure" beam of gamma-ray quanta for studies of cross-
sections of multiparticle photonuclear reactions at the
output of the LUE-40 accelerator [23] using a magnetic
cleaning system relevant and will provide a set of new
experimental data.
When developing such a cleaning magnetic system,
it should be considered that the electrons are scattered in
the converter, so the system should be short, with signif-
icant induction of the magnetic field in the interaction
space to avoid electron beam collimation by magnet
poles. Estimates have shown that tha magnetic induction
value should be around 1 T. The most suitable magnetic
system for this purpose is a system based on permanent
magnets with a special direction of magnetization [24].
One of the implementations of such a magnet is given in
the examples fo the Superfish/Poisson group of codes
[25]. However, such a system requires permanent mag-
nets with a special configuration, which are not widely
available. Therefore, commercially available magnets
with a rectangular cross-section were used for the proto-
type of the magnetic system.
The paper presents the results of calculations, nu-
merical simulations, design, and testing of such a sys-
tem to obtain a "pure" beam of bremsstrahlung quanta
for the study of cross-sections of multiparticle photo-
nuclear reactions at the LUE-40 electron linac.
1. MAGNETIC SYSTEM SIMULATION
Simulation of transverse magnetic field distribution
was performed with the two-dimensional
Superfish/Poisson group of codes under the assumption
that the magnetic system extends infinitely in the longi-
tudinal direction. For such an approach to be applied to
a finite-sized magnet, the air gap of the magnet must be
much smaller than the longitudinal length of the system.
Based on the geometric dimensions and mutual posi-
tioning of the magnet and the irradiation target, it is
necessary, that the bending angle of the beam central
trajectory at the energy of 80 MeV was not less than
15. In the physics of accelerators, a quantity such as
magnetic rigidness is used (see, for example, [26]):
3.3356B pc , where B is the magnetic field in Tesla,
is the electron Larmor radius in meters, pc is electron
energy in gigaelectronvolts. It can be shown that for a
rectangular magnet at small bending angles α the length
of the magnet L is determined by the formula:
3.3356 /L pc B . At the air gap magnetic field of
0.9 T, the length of the magnet at an electron energy of
82 MeV is approximately 80 mm. NdFeB magnets with
a size of 804015 mm are commercially available, so
with an air gap of 20 mm or less, a two-dimensional
code can be used to simulate the magnet.
To increase the field in the gap, a magnetic yoke
made of low-carbon steel was used, which closed the
magnetic flux, forming a so-called "C"-like magnet. The
following magnet parameters were used in the simula-
tion: residual induction Br = 12100 Gs and coercive
force Hc = -11300 Oe. This corresponds to the N38 class
NdFeB magnets we purchased.
A magnetic system simulation of certain optimiza-
tion was performed with such competing criteria as field
induction in the gap, the size of the gap, and the maxi-
mum induction in the magnetic yoke. The minimum
size of the gap was limited by the electron beam size
considering scattering in the converter. The maximum
induction in the gap should be approximately 0.9 T, the
maximum induction in the magnetic yoke should not
exceed 1.5 T.
The final configuration of the magnetic system (its
upper half relative to the plane of symmetry) is shown
in Fig. 1.
Permanent-Magnet Dipole
C:\LANL\NEW3BUILDING\PERMANENTMAGNETLU40\PM_BEND8NDFEB_3.AM 4-22-2021 19:53:26
0
2
4
6
8
10
12
14
0
2
4
6
8
10
12
14
-10 -8 -6 -4 -2 0 2 4 6 8 10
Fig. 1. Magnet system configuration
The system shown in Fig. 1 consists of a block of
permanent magnets (three plates with a total thickness
of 45 mm) and the "C" like magnetic yoke. The thick-
ness of the vertical part of the magnetic yoke is 40 mm,
and that of the horizontal part is 45 mm. To reduce the
magnitude of the field induction at the point of contact
of the permanent magnets with the magnetic yoke on
the left, a notch of 7 mm deep with a rounding radius of
5 mm was made in the horizontal part of the magnetic
yoke. With a magnetic gap of 16 mm, the induction in
the gap is 0.876 T, and this value in the magnetic yoke
does not exceed 1.5 T.
64 ISSN 1562-6016. ВАНТ. 2022. №3(139)
Fig. 2 shows the calculation results of the central tra-
jectory for the case of an electron beam with energies of
44.3 and 82 MeV using the TRANSPORT code [27].
You can see that the magnet provides a beam deflection
of 8 and 4 cm at the distance of 10 cm from the magnet,
respectively.
Fig. 2. The central trajectories of the electron beam
for energies of 44.3 MeV (blue curve)
and 82 MeV (red curve)
1.1. SIMULATION WITH PARMELA
AND GEANT4
An array of macroparticles, which represents an
electron beam simulated by the PARMELA code [28] at
the LUE-40 linac output was introduced into the
GEANT4 program as an event generator. This electron
beam fell on a tantalum converter 0.1 or 0.3 mm thick.
The energy of the beam macroparticles at the maximum
of the distribution was 44.3 MeV, 70% of the particles
fell into the energy range of 3.2%. The number of
macroparticles in the beam was 190,700. The parame-
ters of the electrons that flew forward from the convert-
er were transferred back to the PARMELA code for
further transport of macroparticles. There were two sets
of simulations. In the first set beam divergence after the
converter was studied, so the beamline was represented
just a 10 cm drift space. At a converter thickness of
0.1 mm, the RMS beam size increases in the drift space
by 0.56 cm, which corresponds to a beam standard de-
viation of 56 mrad. With a converter thickness of
0.3 mm, this increase equals 1 cm, which corresponds to
the beam standard deviation of 100 mrad. It should be
noted that the number of macroparticles transmitted to
the PARMELA program is greater than their initial
number. At a converter thickness of 0.1 mm, they are
approximately 3.000 particles larger, and at a thickness
of 0.3 mm that increase is approximately 5.000 parti-
cles.
At the second set, the effect of the magnet was stud-
ied. The beamline was represented by a 0.5 cm drift, the
dipole magnet, and several drifts with a total length of
10 cm. For the energy of the reference particle
44.3 MeV and the magnetic field induction of 0.9 T, the
bending angle of the magnet was 27.5°. The magnet was
set at an angle of 13.8 to the axis of the input beam. At
a converter thickness of 0.1 mm, 92% of particles pass
through the magnet, and at a thickness of 0.3 mm that
value was 70%. The horizontal beam profiles (bending
plane of the magnet) for different thicknesses of the
converter are shown in Fig. 3. These profiles look like
the Gaussian distribution. One can see that for the con-
verter with a thickness of 0.1 mm there is a very small
number of particles at 3 cm from the beam central tra-
jectory. For the converter with thickness of 0.3 mm,
approximately the same number of particles is observed
at 5 cm.
Fig. 3. Horizontal profiles of the electron beam at 10 cm
from the magnet output edge. The blue curve corresponds
to a converter thickness of 0.1 mm and the red curve
corresponds to the thickness of 0.3 mm
A slightly different picture is observed in the vertical
plane (Fig. 4). It is seen that there are no "tails" in the
distributions. Thus, at a converter thickness of 0.1 mm,
the vertical profile of the beam shows signs of limitation
by the aperture of the magnet at a level of approximate-
ly 10% of the maximum. However, with a converter a
thickness of 0.3 mm, this limitation occurs at a level of
approximately 40%. This explains where particles that
do not pass through the magnet are lost.
Fig. 4. Vertical profiles of the electron beam at 10 cm
from the magnet output edge. The blue curve corre-
sponds to a converter thickness of 0.1 mm and the red
curve corresponds to the thickness of 0.3 mm
Therefore, based on the above simulation results, it
can be concluded that such a magnet design is suitable
for cleaning the gamma-ray beam from electrons, at
least for a converter thickness of 0.1 mm. It is known
that the scattering angle of relativistic electrons is in-
versely proportional to their energy, therefore, at parti-
cle energies in the region of 80 MeV, a tantalum con-
verter with a thickness of 0.3 mm can be used. This
question requires a more detailed study to assess the
ISSN 1562-6016. ВАНТ. 2022. №3(139) 65
effect of background radiation from the collision of
electrons with a magnet on the results of multiparticle
photonuclear reactions in the target.
2. MANUFACTURE AND TESTING
OF MAGNETIC SYSTEM
The developed magnet was manufactured by Sci-
ence and Research Establishment “Accelerator” with
NSC KIPT. The magnetic yoke consists of three parts
fastened with steel bolts. These parts are made of low-
carbon steel. Purchased magnetic plates were assembled
in two blocks of three plates. A screw device that allows
one to hold the magnets when pushing them on top of
each other was used at assembling the blocks and in-
stalling the blocks in the magnetic yoke. Magnets in
blocks and blocks in a magnetic yoke are fixed with an
aluminum framework. The appearance of the magnet is
shown in Fig. 5.
Fig. 5. The magnet with a line of Hall sensors
for measuring the magnetic field distribution
To measure the field distribution in the magnet, a
line of 10 linear Hall sensors CYSJ902 [29] was made,
which allows measuring fields up to 2 Tesla with a rela-
tive error of up to 1%. To calibrate the sensors, each of
them in turn was placed at a point with the same field.
The field at this point was measured with an industrial
teslameter. The measurement results are shown in
Fig. 6. The maximum induction in the gap was 0.9 T.
Fig. 6. Magnetic field distribution in a midplane
of the magnet air gap
A comparison of the measured data across the mag-
net in the middle of the pole with the dependence calcu-
lated using the Superfish/Poisson code was carried out.
The measured data were normalized so that the maxi-
mum value coincided with the calculated maximum
value. The measured field distribution in shape coin-
cides well with the calculated one. In absolute terms, the
results differ by 3%.
The integration of the field distribution in the middle
of the magnet poles in the longitudinal direction allowed
us to estimate the fringing fields. The effective length of
the magnet is 82.7 mm with a pole length of 80 mm,
which indicates that the field is well localized within the
magnet.
The magnet was installed at the LUE-40 linac output
(Fig. 7) at an angle of 15 to the linac axis. To study the
effect of the magnet on electron beam dynamics, a se-
ries of experiments was performed at beam energies in
the regions of 40 and 80 MeV. It is known that electron
irradiation causes silicon glass coloring (see, for exam-
ple, [30]) that depends on the absorbed dose, so it is the
simple way to visualize beam transversal density distri-
bution. A glass plate was installed at 90 mm from the
magnet exit in such a way that the plate plane was per-
pendicular to the linac axis at every experiment includ-
ing a configuration without any converter as well as the
configuration with installed 0.1 and 0.3 mm thick tanta-
lum converters.
Fig. 7. The cleaning magnet was installed
at the LUE-40 linac exit
An example of photographs of beam footprints on
the checkered paper background is shown in Fig. 8 at
particle energy of 81 MeV. The black lines at the bot-
tom right correspond to the horizontal position of the
linac axis. A dash at the bottom of the lower footprint is
accidental contamination of the glass.
Fig. 8. Photographs of beam footprints on glass
at the energy of 81 MeV. Top without converter,
bottom with 0.1 mm tantalum converter
Processing the scanned beam footprints we have
concluded that the developed magnet, in principle, can
66 ISSN 1562-6016. ВАНТ. 2022. №3(139)
be used to clean the gamma beam at an electron beam
energy of up to 84 MeV and a converter thickness of up
to 0.3 mm. However, the work that still needs to be
done is the following: recheck the magnet alignment;
estimate the generation of background gamma radiation
in the collision of scattered electrons with the magnet;
integrate the magnet with the irradiation device.
CONCLUSIONS
The results of calculations, numerical modeling, de-
sign, and testing of a magnetic system to obtain a "pure"
beam of bremsstrahlung quanta are presented. This sys-
tem is made on the base of commercially available per-
manent magnets with a rectangular cross-section and is
designed to study the cross-sections of multiparticle
photonuclear reactions at the LUE-40 linac output. The
maximum on axis field is 0.9 T, which provides suffi-
cient separation of the electron beam and gamma rays at
a distance of more than 90 mm from the magnet.
The developed magnet, in principle, can be used to
clean the gamma beam at an electron beam energy of up
to 84 MeV and a converter thickness of up to 0.3 mm.
Due to the use of thin targets-converters, the shape
of the bremsstrahlung spectrum of gamma quanta is
close to the analytical dependence of 1/Eγ. This makes it
possible to apply the photon difference method or the
regularization method and obtain cross-sections of
multiparticle photonuclear nuclear reactions σ(Eγ).
ACKNOWLEDGЕMENTS
The authors thank V.A. Bovda and A.M. Bovda
from the Institute of Solid State Physics, Materials Sci-
ence and Technology NSC KIPT for assistance and use-
ful advice in the design and manufacturing of magnetic
systems.
REFERENCES
1. E.G. Fuller, H. Gerstenberg. Photonuclear Data.
Abstracts Sheets. 1955, 1982. NBSIR 83-2742.
U.S.A. National Bureau of Standards, 1983.
2. V.V. Varlamov, V.V. Sapunenko, M.E. Stepanov.
Photonuclear data 1976-1995. Pointer. M.: “Univer-
sity Press”, 1996.
3. S.S. Dietrich, B.L. Berman. At. Data Nucl. Data
Tables 38, 199, 1988.
4. B.L. Berman, S.C. Fultz // Rev. Mod. Phys. 1975,
v. 47, p. 713.
5. A.V. Varlamov, V.V. Varlamov, D.S. Rudenko,
M.E. Stepanov. Atlas of Giant Dipole Resonances.
Parameters and Graphs of Photonuclear Reaction
Cross Sections. INDC(NDS)-394, IAEA NDS,
Vienna, Austria, 1999.
6. M.B. Chadwick, P. Oblozinsky, P.E. Hodgson,
G. Reffo // Phys. Rev. C. 1991, v. 44, p. 814.
doi.org/10.1103/PhysRevC.44.814.
7. B.S. Ishkhanov and V.N. Orlin // Phys. At. Nucl.
2011, v. 74, p. 19.
8. T.E. Rodrigues, J.D.T. Arruda-Neto, A. Deppman,
V.P. Likhachev, J. Mesa, C. Garcia, K. Shtejer,
G. Silva, S.B. Duarte, and O.A.P. Tavares. Photo-
nuclear reactions at intermediate energies investigat-
ed via the Monte Carlo multicollisional intranuclear
cascade model // Physical Review C. 2004, v. 69,
p. 064611. DOI: 10.1103/PhysRevC.69.064611.
9. M. Herman, R. Capote, B.V. Carlson,
P. Oblozinsky, M. Sin, A. Trkov, H. Wienke,
V. Zerkin. EMPIRE: Nuclear reaction model code
system for data evaluation // Nucl. Data Sheets.
2007, v. 108, p. 2655. EMPIRE Nuclear Reaction
Model Code. https://www-nds.iaea.org/empire/.
10. A.J. Koning, S. Hilaire, and M.C. Duijvestijn.
“TALYS-1.0,” EPJ Web Conf. 2008, 211. Proc. Int.
Conf. on Nuclear Data for Science and Technology,
22-27 Apr., 2007, Nice, France, (Eds.) O. Bersillon,
F. Gunsing, E. Bauge, R. Jacqmin, and S. Leray.
TALYS based evaluated nuclear data library.
http://www.TALYS.eu/home/.
11. O. Iwamoto, N. Iwamoto, S. Kunieda, F. Minato,
and K. Shibata. The CCONE code system and its
application to nuclear data evaluation for fission and
other reactions // Nucl. Data Sheets. 2016, v. 131,
p. 259.
12. T. Kawano. CoH3: The coupled-channels and
HauserFeshbach code. 2019. CNR2018: Internation-
al Workshop on Compound Nucleus and Related
Topics, LBNL, Berkeley, CA, USA, September 24-
28, 2018, (Ed.) J. Escher.
13. Charles D. Bowman, Annu // Rev. Nucl. Part. Sci.
1998, v. 48, p. 505.
14. Y. Gohar, I. Bolshinsky, and I. Karnaukhov. // Se-
cond Int. Workshop Proceedings on Technology and
Components of Accelerator-driven Systems, (Nantes,
France 21-23 May 2013), p. 254-265
[NEA/NSC/DOC(2015)].
15. A.N. Vodin, P.A. Demchenko, A.Yu. Zelinsky,
I.M. Karnaukhov, I.M. Neklyudov, F.A. Peev,
G.D. Pugachev, I.V. Ushakov. NSC KIPT Neutron
Source Status // Problems of Atomic Science and
Technology. Series “Nuclear Physics Investiga-
tions”. 2013, № 6, p. 3-7.
16. J. Allison, K. Amako, J. Apostolakis, et al. Recent
developments in Geant4 // NIM Section A. 2016,
v. 835, p. 186-225.
17. H. Naik, G.N. Kim, R. Schwengner, K. Kim,
M. Zaman, et al. Photoneutron reaction cross-section
for
93
Nb in the end-point bremsstrahlung energies of
12…16 and 45…70 MeV // Nucl. Phys. A. 2013,
v. 916, p. 168-182.
18. A.N. Vodin, O.S. Deiev, I.S. Timchenko, et al. Pho-
toneutron cross-sections for the reactions
181
Ta(;
xn; x=1…8)
181-x
Ta at Emax= 80…95 MeV // Eur.
Phys. J. A. 2021, 57:208. https://doi.org/10.1140/
epja/s10050-021-00484-x, arXiv:2103.09859.
19. A.N. Vodin, O.S. Deiev, V.Yu. Korda, et al. Photo-
neutron reactions on
93
Nb at Eγmax=33…93 MeV //
Nucl. Phys. 2021, A1014, 122248.
doi.org/10.1016/j.nuclphysa.2021.122248,
arXiv:2101.08614.
20. A.N. Vodin, O.S. Deiev, S.M. Olejnik. Activation of
93
Nb Nuclei on the Linac LUE-40 of RDC “Acceler-
ator” and Determination of Photonuclear Reaction
Cross-Sections // Problems of Atomic Science and
Technology. Series “Nuclear Physics Investiga-
tions”. 2019, № 6, p. 122-127.
https://www-nds.iaea.org/empire/
http://www.talys.eu/home/
https://www.sciencedirect.com/science/article/abs/pii/S0375947413006982#%21
https://www.sciencedirect.com/science/article/abs/pii/S0375947413006982#%21
https://www.sciencedirect.com/science/article/abs/pii/S0375947413006982#%21
https://www.sciencedirect.com/science/article/abs/pii/S0375947413006982#%21
https://www.sciencedirect.com/science/article/abs/pii/S0375947413006982#%21
https://www.sciencedirect.com/science/journal/03759474
https://www.sciencedirect.com/science/journal/03759474/916/supp/C
https://www.scopus.com/authid/detail.uri?authorId=14621880500
https://doi.org/10.1140/%20epja/s10050-021-00484-x
https://doi.org/10.1140/%20epja/s10050-021-00484-x
https://arxiv.org/search/nucl-ex?searchtype=author&query=Vodin%2C+A+N
https://arxiv.org/search/nucl-ex?searchtype=author&query=Deiev%2C+O+S
https://arxiv.org/search/nucl-ex?searchtype=author&query=Korda%2C+V+Y
https://www.sciencedirect.com/science/journal/03759474
https://www.sciencedirect.com/science/journal/03759474/1014/supp/C
ISSN 1562-6016. ВАНТ. 2022. №3(139) 67
21. S.S. Belyshev, A.N. Ermakov, B.S. Ishkhanov, et al.
Studying photonuclear reactions using the activation
technique // Nuclear Instruments and Methods in
Physics Research. 2014, A745, p. 133-137.
22. L.M. Young. Photoneutron Cross Sections and Spec-
tra from Monoenergetic Photons on Yttrium,
Praseodimium, Lead, and Bismuth in the Giant Res-
onance // Ph.D. Thesis, University of Illinois, USA,
1972.
23. N.I. Ayzatsky, V.I. Beloglazov, V.P. Bozhko, et al.
Electron 100 MeV linac based facility to nuclear
physical experimental investigation // Problems of
Atomic Science and Technology. Series “Nuclear
Physics Investigations”. 2010, № 2, p. 18-22.
24. K. Halbach. Design of permanent multipole magnets
with oriented rare earth cobalt material // NIM. 1980,
169, p. 1-10.
25. J.H. Billen and L.M. Young. POISSON/
SUPERFISH on PC compatibles. Proc. 1993 Particle
Accelerator Conff. Washington (USA). 1993,
p. 790-792.
26. E. Wilson, B.J. Holzer. Beam Dynamics. In: Myers
S., Schopper H. (eds) Particle Physics Reference Li-
brary. Springer, Cham. 2020.
https://doi.org/10.1007/978-3-030-34245-6_2.
27. K.L. Brown, F. Rothacker, D.C Carey, C. Iselin.
TRANSPORT a computer program for designing
charged particle beam transport systems (CERN-80-
04) // European Organization for Nuclear Research
(CERN). 1980.
28. L.M. Young. PARMELA. Los Alamos: 1996, 93 p.
(preprint / Los Alamos National Laboratory, LA-
UR-96-1835).
29. CYSJ902 GaAs Hall Effect Element.
http://www.hallsensors.de/CYSJ902.pdf.
30. V.T. Gritsyna, T.A. Bazilevskaya, V.S. Voitsenya, et
al. Accumulation of stable optical centres in silica
glasses under pulse beam irradiation // J. Nucl. Ma-
ter. 1996, v. 233-237, p. 1310-1317.
Article received 08.02.2022
МАГНІТНА СИСТЕМА ДЛЯ ОЧИЩЕННЯ ГАММА-ПУЧКА НА ВИХІДІ ПРИСКОРЮВАЧА
ЕЛЕКТРОНІВ ЛУЕ-40
В.В. Митроченко, С.О. Пережогін, Л.І. Селіванов, В.Ф. Жигло, А.М. Водін, О.С. Деєв, С.М. Олійник,
І.С. Тімченко, В.А. Кушнір
Гальмівне випромінювання прискорених електронів, що проходять через конвертер, використовується
для дослідження багаточастинкових фотоядерних реакцій. Наведено результати розрахунків чисельного
моделювання, проєктування та випробування спеціальної системи магнітного очищення для отримання
«чистого» пучка квантів гальмівного випромінювання при дослідженні перерізів таких реакцій на
прискорювачі ЛУЕ-40. Система базується на основі наявних у продажу постійних магнітів прямокутного
перерізу. Максимальне поле на осі становить 0,9 Тл, що забезпечує достатнє розділення електронного пучка
й гамма-променів на відстані більше 90 мм від магніту.
МАГНИТНАЯ СИСТЕМА ОЧИСТКИ ГАММА-ПУЧКА НА ВЫХОДЕ УСКОРИТЕЛЯ
ЭЛЕКТРОНОВ ЛУЭ-40
В.В. Митроченко, С.О. Пережогин, Л.И. Селиванов, В.Ф. Жигло, А.Н. Водин, О.С. Деев, С.М. Олейник,
И.С. Тимченко, В.А. Кушнир
Тормозное излучение ускоренных электронов, прошедших конвертер, используется для изучения много-
частичных фотоядерных реакций. Представлены результаты расчетов численного моделирования, проекти-
рования и испытаний специальной системы магнитной очистки для получения «чистого» пучка тормозных
квантов при исследовании сечений таких реакций на линейном ускорителе ЛУЭ-40. Система базируется на
основе серийно выпускаемых постоянных магнитов прямоугольного сечения. Максимальное осевое поле
составляет 0,9 Тл, что обеспечивает достаточное разделение электронного пучка и гамма-квантов на рас-
стоянии более 90 мм от магнита.
http://www.hallsensors.de/CYSJ902.pdf
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