Compact activation detectors for measuring of neutron emission on Plasma Focus installations
The paper presents the two compact simple systems for the measurement of the absolute neutron yield in the range 10⁶ –10¹² neutrons/pulse and higher and spatial anisotropy of neutron radiation. The systems are destined for the registration of the short duration neutron radiation of the pulsed plasma...
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| Опубліковано в: : | Вопросы атомной науки и техники |
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| Дата: | 2005 |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2005
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| Цитувати: | Compact activation detectors for measuring of neutron emission on Plasma Focus installations / O.N. Krokhin, V.Ya. Nikulin, E.N. Peregudova, I.V. Volobuev // Вопросы атомной науки и техники. — 2005. — № 1. — С. 101-103. — Бібліогр.: 9 назв. — англ. |
Репозитарії
Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1860242731761139712 |
|---|---|
| author | Krokhin, O.N. Nikulin, V.Ya. Peregudova, E.N. Volobuev, I.V. |
| author_facet | Krokhin, O.N. Nikulin, V.Ya. Peregudova, E.N. Volobuev, I.V. |
| citation_txt | Compact activation detectors for measuring of neutron emission on Plasma Focus installations / O.N. Krokhin, V.Ya. Nikulin, E.N. Peregudova, I.V. Volobuev // Вопросы атомной науки и техники. — 2005. — № 1. — С. 101-103. — Бібліогр.: 9 назв. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| description | The paper presents the two compact simple systems for the measurement of the absolute neutron yield in the range 10⁶ –10¹² neutrons/pulse and higher and spatial anisotropy of neutron radiation. The systems are destined for the registration of the short duration neutron radiation of the pulsed plasma installations, such as Plasma Focus (PF), z-pinches and others plasma installations. This paper also includes the results of the neutron emission measurements on different PF installations: "Tulip" (P.N. Lebedev Physical Institute, Moscow, Russia), the PF–1000 and PF–150 installations (Institute of Plasma Physics and Laser Microfusion, Warsaw, Poland).
У роботі представлені дві прості малогабаритні системи для виміру абсолютного нейтронного виходу в області 10⁶ –10¹² нейтронів/імпульс і вище і просторової анізотропії нейтронного випромінювання. Системи призначені для реєстрації короткого по тривалості нейтронного випромінювання імпульсних плазмових установок, таких як Плазмовий фокус (ПФ), z-пінчи й інших. У роботі також приведені результати по виміру нейтронної емісії на різних ПФ установках: «Тюльпан» (Фізичний інститут ім. П.Н. Лебедєва, Москва, Росія), PF–1000 і PF–150 (Інститут фізики плазми і лазерного мікросинтезу, Варшава, Польща).
В работе представлены две простые малогабаритные системы для измерения абсолютного нейтронного вы хода в области 10⁶ –10¹² нейтронов/импульс и выше и пространственной анизотропии нейтронного излучения. Системы предназначены для регистрации короткого по длительности нейтронного излучения импульсных плаз менных установок, таких как Плазменный фокус (ПФ), z-пинчи и других. В работе также приведены результа ты по измерению нейтронной эмиссии на различных ПФ установках: «Тюльпан» (Физический институт им. П.Н. Лебедева, Москва, Россия), PF–1000 и PF–150 (Институт физики плазмы и лазерного микросинтеза, Варшава, Польша).
|
| first_indexed | 2025-12-07T18:31:56Z |
| format | Article |
| fulltext |
COMPACT ACTIVATION DETECTORS FOR MEASURING OF NEUTRON
EMISSION ON PLASMA FOCUS INSTALLATIONS
O.N. Krokhin, V.Ya. Nikulin, E.N. Peregudova, and I.V. Volobuev
P.N. Lebedev Physical Institute of Russian Academy of Sciences, Moscow, Russia
The paper presents the two compact simple systems for the measurement of the absolute neutron yield in the range
106–1012 neutrons/pulse and higher and spatial anisotropy of neutron radiation. The systems are destined for the registra
tion of the short duration neutron radiation of the pulsed plasma installations, such as Plasma Focus (PF), z-pinches and
others plasma installations. This paper also includes the results of the neutron emission measurements on different PF
installations: "Tulip" (P.N. Lebedev Physical Institute, Moscow, Russia), the PF–1000 and PF–150 installations (Insti
tute of Plasma Physics and Laser Microfusion, Warsaw, Poland).
PACS: 52.58.Lq; 52.70.Nc
1. INTRODUCTION
The neutron measurements are usually conducted on
the every Plasma Focus installations. On the base of the
results received by the neutron measurements on such in
stallations the dependence of the neutron yield on the en
ergy stored in capacitors (scaling law) was obtained.
However, since the methods, used in those experiments
for the neutron measurements, the absolute calibration of
detectors, the background of low-velocity and moderate-
energy neutrons were different, some degree of uncertain
ty can take place. Therefore it is necessary to carry out the
neutron measurements on different installations with the
same neutron measurement system (at most simple and
mobile). In the paper we describe the devices for neutron
measurements, which allow to measure of neutron yield
with a good accuracy on different installations without the
additional calibration.
2. THE SYSTEMS FOR THE NEUTRON
MEASUREMENTS
Two compact simple systems for the measurement of
the absolute neutron yield (106–1012 neutrons/pulse and
higher) and spatial anisotropy of neutron radiation were
developed in the Lebedev Physical Institute (Fig. 1). The
systems are destined for the registration of short duration
neutron radiation of the pulsed plasma installations.
These systems are minimally sensitive to background
of low-velocity neutrons and have been calibrated as mo
bile instruments (in other words, the calibration parame
ters have to be unchanged when we place the neutron reg
istration systems in different positions on different instal
lations) [1–3].
The first system consists of minimal number of
recording devices and compact interchangeable activation
detectors with different dimensions of moderator contain
ers. The electronic unit is built on the TTL standard; the
AAA-accumulators are used in power supply of the elec
tronic system.
The second system utilizes the same small activation
detectors. The small optically isolated electronics package
has 4-digit data output to LCD display and is screwed to
the sensor of the detector. In the power supply of the elec
tronic unit and the sensor the 9V accumulator is used.
Fig.1. Different detectors of the neutron registration sys
tems. The size of containers with moderator: cylinders
with diameter 3.5, 6.5, and 14 cm and length 12, 11, and
20 cm correspondingly
The developed neutron measurement systems utilize
the halogenous Geiger–Muller counters of the CTC–5 and
CTC–6 types as sensors (Russia) that is wrapped with in
dium or silver foils and placed in the containers filled
with the neutron moderator. As it is known, for such rela
tively small moderator containers, the dimension of the
moderator determines the sensitivity of the device—the
larger moderator, the higher sensitivity. On the other
hand, the larger the size of the moderator, the influence of
background of low-velocity neutrons is heavier. (Low-ve
locity neutrons arise due to the scattering of fast neutrons
in the material of the constructing elements of the installa
tion, neutron shield packages, and walls.) Taking all that
into account, we have determined the optimal size of the
containers with moderator. The material of the moderator
is plexiglas (or paraffin) covered with cadmium foil. Cad
mium is used in order to reduce the influence of low-ve
locity neutrons on the results of measurements (the cad
mium capture cross-section for thermal neutrons is very
large one). The experiments conducted on the various in
stallations have confirmed the correctness of the chosen
parameters of the neutron detectors.
Rather low efficiency of the neutron detectors imposes
severe conditions on the resolution time of the counter
electronic circuit. In order to increase the efficiency of the
neutron detectors it is desirable to reduce the miscounts of
the recording system. With the purpose to reduce the mis
Problems of Atomic Science and Technology. 2005. № 1. Series: Plasma Physics (10). P. 101-103 101
counts, obviously, the resolution time of recording system
is necessary to make as short as possible. For the given
variant of the neutron detectors the resolution time of
recording system was approximately equal to 120 μs that
is only a little longer than the dead time of the sensors.
The two nuclear reactions give an important contribu
tion to activation of indium or silver foil. Corresponding
ly [4, 5]:
In115 n
In116 ⇒ Sn116 β−
σ act = 52 Barn, T 1
2
= 13 s,
Eβ = 3.29 MeV
In115 n
In116m ⇒ Sn116 β−g
σ аcт = 155 Barn, T 1
2
= 54.2 min,
Eβ = 1 MeV; 0.87 MeV; 0.60 MeV
and
Ag107 n
Ag108 ⇒ Cd108 β− g
σ act = 45 Barn, T 1
2
= 2.3 min,
Eβ = 1.77 MeV; 1.15 MeV
Ag109 n
Ag110 ⇒ Cd110 β−g
σ аcт = 113 Barn, T 1
2
= 24.2 s,
Eβ = 2.24 MeV; 2.82 MeV
The neutron measurement systems were calibrated
with Po–Be, Pu–Be, and Americium–241/Beryllium
sources. The procedure of calibration of the neutrons
counters with indium foils is given in [2]. The influence
of the low-velocity and moderate-energy neutrons back
ground to experimental results have been tested by the in
dependent measurements of the neutron yield [6].
The recorded neutron output is
NΔN − N ph
Δt =I 4π [ ε ' T '1 −e
t1
T ' e
−t2
T '1 −e−Δt
T '
ε ' ' T ' '1 −e
−t 1
T ' ' e
−t2
T ' '1 −e−Δt
T ' '. 1
The single and double primes indicate the parameters of
reactions, which we have written for two indium isomers
or silver isotopes (In116 and In116m or Ag108 and Ag110).
N—the recorded number of pulses;
ΔN —the errors of the recording system;
I—the intensity of the neutron source;
ε —the effectiveness of detector;
Δt —the measurement time;
t1—the irradiation time;
t2—the time interval between the irradiation end and the
counter beginning;
N ph
Δt —the average number of background pulses for
Δt ;
—solid angle at which the detector is visible from the
location of the pulsed neutron source;
T=
T 1
2
ln 2
—the relaxation time of a radioactivity;
T 1
2
—the half-life of corresponding foil isotope.
CALIBRATION CONDITIONS
t 1 >>T ' , T ' ' ; t 2≃0 ; Δt=1 s
ε≡ε 'ε ' '=NΔN − N ph
Δt / I /4π . 2
REAL NEUTRON MEASUREMENTS
For In foil:
NΔN − N ph
Δt
= I 1 4π ε[0 . 2511 −e
−Δt
T '0 . 7491 −e
−Δt
T ' '] , 3
where T '=20 .34 s, T ' '=4683 s, I 1 is the neu
tron yield for shot.
For Ag foil:
NΔN − N ph
Δt
¿ I 14π ε[0 . 2491 −e
−Δt
T '0 . 7151 −e
−Δt
T ' '] , 4
where T '=199 s, T ' '=35 s.
Fig.2. The maximum neutron yield on the different Plas
ma Focus installations. ●— measurements with these di
agnostic systems; ■—data from the literature
3. RESULTS AND DISCUSSIONS
The results of the neutron measurements are presented
in Figures 2–3. In Fig. 2 one can see that the character of
the neutron emission of two installations (PF–4 and PF–
150) is close to the E2 law, the neutron emission on others
PF installations are significantly lower. The reasons of
such low yield could be:
• the shape and dimensions of the electrodes are not opti
mum;
102
• a restriction of the ion component of the current that
could be arise in the near anode area on the big PF instal
lations [7];
• the loss of the current due to the pinch rotation [8];
• the splitting of the pinch into filaments [9];
• the secondary breakdowns near the insulator,
and others.
The neutron emission can exhibit a strong forward di
rected anisotropy. Anisotropy factors Y0/Y90 and Y0/Y180 in
the range between 1 and 2 were measured (Y0, Y90, and
Fig.3. Spatial neutron anisotropy measured with these
neutron activation counters systems
Y180—correspondingly neutron yields at the angles 0ο, 90ο
, and 180ο to the Z-axis of PF).
The figures show that anisotropy factor decreases with
the increase of gas pressure in PF chamber. We also ob
served that anisotropy is higher in shots with high neutron
yield (especially for the factor Y0/Y180). The high spatial
anisotropy is an indication of the dominant role of axially
directed ion beams in the neutron generation process.
Fig. 3(a) shows that the role of the accelerating mecha
nism of the neutron production on the large installations is
less than one on the small PF devices. The accelerating
mechanism, as it seen from the Fig. 3(b), is suppressed by
the increase of the pressure of the operating gas.
ACKNOWLEDGEMENTS
This work was supported by Grant of President
of RF # НШ-59.2003.2 and by the Education–Sci
ence Center “Integration” (project № Б00049).
REFERENCES
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МАЛОГАБАРИТНЫЕ АКТИВАЦИОННЫЕ ДЕТЕКТОРЫ ДЛЯ ИЗМЕРЕНИЯ
НЕЙТРОННОЙ ЭМИССИИ НА УСТАНОВКАХ ТИПА «ПЛАЗМЕННЫЙ ФОКУС»
И.В. Волобуев, О.Н. Крохин, В.Я. Никулин и Е.Н. Перегудова
В работе представлены две простые малогабаритные системы для измерения абсолютного нейтронного вы
хода в области 106–1012 нейтронов/импульс и выше и пространственной анизотропии нейтронного излучения.
Системы предназначены для регистрации короткого по длительности нейтронного излучения импульсных плаз
менных установок, таких как Плазменный фокус (ПФ), z-пинчи и других. В работе также приведены результа
ты по измерению нейтронной эмиссии на различных ПФ установках: «Тюльпан» (Физический институт им.
П.Н. Лебедева, Москва, Россия), PF–1000 и PF–150 (Институт физики плазмы и лазерного микросинтеза, Вар
шава, Польша).
МАЛОГАБАРИТНІ АКТИВАЦІЙНІ ДЕТЕКТОРИ ДЛЯ ВИМІРУ
НЕЙТРОННОЇ ЕМІСІЇ НА УСТАНОВКАХ ТИПУ «ПЛАЗМОВИЙ ФОКУС»
І.В. Волобуєв, О.Н. Крохін, В.Я. Нікулін і Є.Н. Перегудова
103
а
b
У роботі представлені дві прості малогабаритні системи для виміру абсолютного нейтронного виходу в області
106–1012 нейтронів/імпульс і вище і просторової анізотропії нейтронного випромінювання. Системи призначені
для реєстрації короткого по тривалості нейтронного випромінювання імпульсних плазмових установок, таких
як Плазмовий фокус (ПФ), z-пінчи й інших. У роботі також приведені результати по виміру нейтронної емісії
на різних ПФ установках: «Тюльпан» (Фізичний інститут ім. П.Н. Лебедєва, Москва, Росія), PF–1000 і PF–150
(Інститут фізики плазми і лазерного мікросинтезу, Варшава, Польща).
104
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| id | nasplib_isofts_kiev_ua-123456789-78886 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-12-07T18:31:56Z |
| publishDate | 2005 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Krokhin, O.N. Nikulin, V.Ya. Peregudova, E.N. Volobuev, I.V. 2015-03-22T10:11:26Z 2015-03-22T10:11:26Z 2005 Compact activation detectors for measuring of neutron emission on Plasma Focus installations / O.N. Krokhin, V.Ya. Nikulin, E.N. Peregudova, I.V. Volobuev // Вопросы атомной науки и техники. — 2005. — № 1. — С. 101-103. — Бібліогр.: 9 назв. — англ. 1562-6016 PACS: 52.58.Lq; 52.70.Nc https://nasplib.isofts.kiev.ua/handle/123456789/78886 The paper presents the two compact simple systems for the measurement of the absolute neutron yield in the range 10⁶ –10¹² neutrons/pulse and higher and spatial anisotropy of neutron radiation. The systems are destined for the registration of the short duration neutron radiation of the pulsed plasma installations, such as Plasma Focus (PF), z-pinches and others plasma installations. This paper also includes the results of the neutron emission measurements on different PF installations: "Tulip" (P.N. Lebedev Physical Institute, Moscow, Russia), the PF–1000 and PF–150 installations (Institute of Plasma Physics and Laser Microfusion, Warsaw, Poland). У роботі представлені дві прості малогабаритні системи для виміру абсолютного нейтронного виходу в області 10⁶ –10¹² нейтронів/імпульс і вище і просторової анізотропії нейтронного випромінювання. Системи призначені для реєстрації короткого по тривалості нейтронного випромінювання імпульсних плазмових установок, таких як Плазмовий фокус (ПФ), z-пінчи й інших. У роботі також приведені результати по виміру нейтронної емісії на різних ПФ установках: «Тюльпан» (Фізичний інститут ім. П.Н. Лебедєва, Москва, Росія), PF–1000 і PF–150 (Інститут фізики плазми і лазерного мікросинтезу, Варшава, Польща). В работе представлены две простые малогабаритные системы для измерения абсолютного нейтронного вы хода в области 10⁶ –10¹² нейтронов/импульс и выше и пространственной анизотропии нейтронного излучения. Системы предназначены для регистрации короткого по длительности нейтронного излучения импульсных плаз менных установок, таких как Плазменный фокус (ПФ), z-пинчи и других. В работе также приведены результа ты по измерению нейтронной эмиссии на различных ПФ установках: «Тюльпан» (Физический институт им. П.Н. Лебедева, Москва, Россия), PF–1000 и PF–150 (Институт физики плазмы и лазерного микросинтеза, Варшава, Польша). This work was supported by Grant of President of RF # НШ-59.2003.2 and by the Education–Science Center “Integration” (project № Б00049). en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Plasma dynamics and plasma wall interaction Compact activation detectors for measuring of neutron emission on Plasma Focus installations Малогабаритні активаційні детектори для виміру нейтронної емісії на установках типу «Плазмовий фокус» Малогабаритные активационные детекторы для измерения нейтронной эмиссии на установках типа «Плазменный фокус» Article published earlier |
| spellingShingle | Compact activation detectors for measuring of neutron emission on Plasma Focus installations Krokhin, O.N. Nikulin, V.Ya. Peregudova, E.N. Volobuev, I.V. Plasma dynamics and plasma wall interaction |
| title | Compact activation detectors for measuring of neutron emission on Plasma Focus installations |
| title_alt | Малогабаритні активаційні детектори для виміру нейтронної емісії на установках типу «Плазмовий фокус» Малогабаритные активационные детекторы для измерения нейтронной эмиссии на установках типа «Плазменный фокус» |
| title_full | Compact activation detectors for measuring of neutron emission on Plasma Focus installations |
| title_fullStr | Compact activation detectors for measuring of neutron emission on Plasma Focus installations |
| title_full_unstemmed | Compact activation detectors for measuring of neutron emission on Plasma Focus installations |
| title_short | Compact activation detectors for measuring of neutron emission on Plasma Focus installations |
| title_sort | compact activation detectors for measuring of neutron emission on plasma focus installations |
| topic | Plasma dynamics and plasma wall interaction |
| topic_facet | Plasma dynamics and plasma wall interaction |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/78886 |
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