Composite scintillators as new type of a scintillation material
For radioecological tasks, we have developed a new type of scintillation materials - composite scintillators, consisting of dielectric gel as a base into which granules of scintillating substances were introduced. It has been shown that such material can be created both on the basis of organic and i...
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
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nasplib_isofts_kiev_ua-123456789-804902025-02-09T14:08:06Z Composite scintillators as new type of a scintillation material Композиционные сцинтилляторы как новый вид сцинтилляционного материала Композицiйнi сцинтилятори як новий вид сцинтиляцiйного матерiалу Karavaeva, N.L. Ядерно-физические методы и обработка данных For radioecological tasks, we have developed a new type of scintillation materials - composite scintillators, consisting of dielectric gel as a base into which granules of scintillating substances were introduced. It has been shown that such material can be created both on the basis of organic and inorganic granules. In the first case, efficient fast neutron detectors can be created, with neutron discrimination on the background of gamma-radiation close to organic single crystals. In the second case, efficient detectors of thermal neutrons could be developed, with variation of the granule size allowing substantial reduction of the effects of background radiation. Separate fragments of the scintillator can be linked together, creating endless planes. A possibility of using bases with higher radiation hardness as compared with standard scintillator bases, as well as using any scintillating substance for granules allows thinking about possible application of such technological approach not only for radioecological tasks (ultra-low fluxes), but also in high energy physics. Для радиоэкологических задач нами был разработан новый вид сцинтилляционного материала композиционные сцинтилляторы, состоящие из диэлектрического геля в качестве основы, в которую внедрены гранулы сцинтиллирующего вещества. Показано, что данный материал может создаваться как на основе органических, так и неорганических гранул. Первые позволяют создавать эффективные детекторы быстрых нейтронов со степенью разделения нейтронов на фоне гамма-излучения, близкой к органическим монокристаллам. Вторые явились эффективными детекторами тепловых нейтронов, а варьирование размеров их гранул позволило существенно уменьшить влияние фоновых излучений. Отдельные фрагменты сцинтиллятора можно соединять вместе, создавая бесконечные плоскости. Возможность выбора более радиационно-стойких основ, чем стандартные сцинтилляционные основы, и любых сцинтилляционных веществ для создания гранул позволяет задуматься о возможности использования такого технологического подхода не только для задач радиоэкологии (сверхмалые потоки), но и для задач физики высоких энергий. Для радiоекологiчних задач нами був розроблений новий вид сцинтиляцiйного матерiалу композицiйнi сцинтилятори, що складаються з дiелектричного гелю в якостi основи, в яку введенi гранули сцинтилюючої речовини. Показано, що даний матерiал може створюватися як на основi органiчних, так i неорганiчних гранул. Першi дозволяють створювати ефективнi детектори швидких нейтронiв з ступенем подiлу нейтронiв на фонi гамма- випромiнювання, близькою до органiчних монокристалiв. Другi є ефективними детекторами теплових нейтронiв, а варiювання розмiрiв їх гранул дозволило iстотно зменшити вплив фонових випромiнювань. Окремi частини сцинтилятора можна з'єднувати разом, створюючи нескiнченнi площi. Можливiсть вибору бiльш радiацiйностiйких основ, нiж стандартнi сцинтиляцiйнi основи, та будь-яких сцинтиляцiйних речовин для створення гранул дозволяє замислитися про можливiсть використання такого технологiчного пiдходу не тiльки для задач радiоекологiї (надслабкi потоки), а й для задач фiзики високих енергiй. This work was supported by the State Fund for Fundamental Research of Ukraine (project No. F58/06, ”The effect of large radiation doses on scintillation and optical properties of novel types of organic detectors”). 2014 Article Composite scintillators as new type of a scintillation material / N.L. Karavaeva // Вопросы атомной науки и техники. — 2014. — № 5. — С. 91-97. — Бібліогр.: 20 назв. — англ. 1562-6016 PACS: 29.40.Mc, 81.05.Zx https://nasplib.isofts.kiev.ua/handle/123456789/80490 en Вопросы атомной науки и техники application/pdf Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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Ядерно-физические методы и обработка данных Ядерно-физические методы и обработка данных |
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Ядерно-физические методы и обработка данных Ядерно-физические методы и обработка данных Karavaeva, N.L. Composite scintillators as new type of a scintillation material Вопросы атомной науки и техники |
| description |
For radioecological tasks, we have developed a new type of scintillation materials - composite scintillators, consisting of dielectric gel as a base into which granules of scintillating substances were introduced. It has been shown that such material can be created both on the basis of organic and inorganic granules. In the first case, efficient fast neutron detectors can be created, with neutron discrimination on the background of gamma-radiation close to organic single crystals. In the second case, efficient detectors of thermal neutrons could be developed, with variation of the granule size allowing substantial reduction of the effects of background radiation. Separate fragments of the scintillator can be linked together, creating endless planes. A possibility of using bases with higher radiation hardness as compared with standard scintillator bases, as well as using any scintillating substance for granules allows thinking about possible application of such technological approach not only for radioecological tasks (ultra-low fluxes), but also in high energy physics. |
| format |
Article |
| author |
Karavaeva, N.L. |
| author_facet |
Karavaeva, N.L. |
| author_sort |
Karavaeva, N.L. |
| title |
Composite scintillators as new type of a scintillation material |
| title_short |
Composite scintillators as new type of a scintillation material |
| title_full |
Composite scintillators as new type of a scintillation material |
| title_fullStr |
Composite scintillators as new type of a scintillation material |
| title_full_unstemmed |
Composite scintillators as new type of a scintillation material |
| title_sort |
composite scintillators as new type of a scintillation material |
| publisher |
Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
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2014 |
| topic_facet |
Ядерно-физические методы и обработка данных |
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https://nasplib.isofts.kiev.ua/handle/123456789/80490 |
| citation_txt |
Composite scintillators as new type of a scintillation material / N.L. Karavaeva // Вопросы атомной науки и техники. — 2014. — № 5. — С. 91-97. — Бібліогр.: 20 назв. — англ. |
| series |
Вопросы атомной науки и техники |
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2025-11-26T16:16:24Z |
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2025-11-26T16:16:24Z |
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| fulltext |
COMPOSITE SCINTILLATORS AS NEW TYPE OF A
SCINTILLATION MATERIAL
N.L.Karavaeva∗
Institute for Scintillation Materials, National Academy of Sciences of Ukraine,
60 Lenin Avenue, 61001, Kharkov, Ukraine
(Received May 16, 2014)
For radioecological tasks, we have developed a new type of scintillation materials – composite scintillators, consisting
of dielectric gel as a base into which granules of scintillating substances were introduced. It has been shown that such
material can be created both on the basis of organic and inorganic granules. In the first case, efficient fast neutron
detectors can be created, with neutron discrimination on the background of gamma-radiation close to organic single
crystals. In the second case, efficient detectors of thermal neutrons could be developed, with variation of the granule
size allowing substantial reduction of the effects of background radiation. Separate fragments of the scintillator can be
linked together, creating endless planes. A possibility of using bases with higher radiation hardness as compared with
standard scintillator bases, as well as using any scintillating substance for granules allows thinking about possible
application of such technological approach not only for radioecological tasks (ultra-low fluxes), but also in high energy
physics.
PACS: 29.40.Mc, 81.05.Zx
1. INTRODUCTION
Earlier, we proposed a technology for preparation of
new type of organic scintillation materials for efficient
detection of fast and thermal neutrons. This allowed
creation of detectors without limitations imposed on
area and shape of the input window [1, 2]. The ob-
tained scintillation materials and detectors on their
base are characterized by high universality, simplic-
ity of their use and possibility of their application for
wide spectrum of problems related to detection and
identification of ionizing radiations. However, not
all possibilities of this technological approach have
been used. Thus, with a new generation of acceler-
ators, irradiation of detectors in these installations
became much stronger. Unique possibilities of com-
posite scintillators make it promising to create scin-
tillation systems with high radiation stability. In this
paper, we present our analysis of possible applications
of composite scintillators.
2. APPLICATION OF COMPOSITE
SCINTILLATORS
2.1. Fast neutron detectors
In a hydrogen-containing organic material, fast neu-
trons generate recoil protons, with their maximum
energy equal the energy of neutrons. Thus, organic
scintillators and detectors on their base can be used
for spectroscopy of fast neutrons [3].
We have developed composite scintillators that,
like organic single crystals, were able to discern parti-
cles by the shape of scintillation pulse. The schemes
used for separation between the radiation to be de-
tected and the background were presented in our
previous works [4, 5, 6, 7]. These schemes allow de-
termining the spectra of recoil protons. Appropriate
processing by numerical differentiation allows obtain-
ing, after reconstruction, of the Pu-Be source neutron
spectrum. As an example, Fig.1 shows the obtained
neutron spectrum of Pu-Be source for a composite
scintillator based on stilbene granules with linear di-
mensions of granules L from 1.7 to 2.0 mm. The scin-
tillator dimensions: diameter 30 mm, height 20 mm.
100 200 300 400 500 600 700 800 900
0
500
1000
1500
2000
2500
N
um
be
r o
f d
et
ec
te
d
ne
ut
ro
ns
Channel Number
3
98
7
6
5
4
32
1
Fig.1. Reconstructed neutron spectrum of 239Pu-Be
source for composite scintillator on the basis of stil-
bene granules with linear dimensions of granules L
from 1.7 to 2.0 mm
In Fig.1, peaks 1 – 9 correspond to energies 3.1; 4.2;
4.9; 6.4; 6.7; 7.3; 7.9; 8.6 and 9.7 MeV of neutrons
emitted by 239Pu-Be source [8].
∗Corresponding author E-mail address: karavaeva77@rambler.ru
ISSN 1562-6016. PROBLEMS OF ATOMIC SCIENCE AND TECHNOLOGY, 2014, N5 (93).
Series: Nuclear Physics Investigations (63), p.91-97.
91
When the granule size is optimal, we can obtain
spectra identical to those with a single crystal; with
grain size smaller than or comparable to the path of
recoil protons, the spectrum will be smeared.
One should note that detection selectivity with
our samples was confirmed by studies of our col-
leagues in Poland [9], as well as in China and South
Korea [10].
2.2. Thermal neutron detectors
The next step in the use of broad possibilities offered
by our technological approach is creation of compos-
ite scintillators for detection of thermal neutrons on
the basis of Ce:GSO and Ce:GPS.
These substances were chosen because of their
uniquely high cross-section of thermal neutron radi-
ation capture by gadolinium nuclides 155Gd, 157Gd,
alongside with high content of these nuclides in the
natural raw material. This allows using a natural
mixture of gadolinium nuclides without its additional
enrichment. As a result of thermal neutron capture,
gadolinium emits conversion electrons, as well as pho-
tons of characteristic X-ray and gamma radiation.
When the edge effect is small, gadolinium-based scin-
tillators should exhibit a characteristic peak of 33 keV
energy, alongside with another peak at 77 keV, which
is the sum of the 33 keV peak of conversion electrons
and 44 keV – of X-ray radiation [11].
To obtain thermal neutrons, we used a calibrated
paraffin sphere with a 239Pu-Be source inside. The
yield of thermal neutrons was 9% of the total fast neu-
tron flux (105 neutrons/s). The thermal neutron peak
was identified by the ”cadmium difference” method.
To reduce the number of gamma-radiation photon de-
tection events, a lead shield of 2.5 cm thickness was
used.
The efficiency of thermal neutron detection was
estimated as follows:
εth =
NΣ
t · Ffast · ηth · S
4πR2
× 100%, (1)
where NΣ is the number of events of thermal neutron
detection, t is the time of accumulation of the events
(spectrum); Ffast is the number of fast neutron emit-
ted by the source per second, ηth=0,09 is the number
of neutrons moderated in the paraffin sphere to ther-
mal energy per one fast neutron, S is the thermal
neutron detector area, R is the distance between the
source and the detector.
The value εγ (Fig.6) was calculated as
εγ = 1− exp(−µρρξd), (2)
where µρ is the mass attenuation coefficient of X-ray
radiation [12], ρ is the density, ξ is the volume frac-
tion of crystalline granules for Ce:GSO and Ce:GPS
(see Chapter 3.3)), d is the scintillator thickness. It
was assumed that d was equal to the average grain
size in the given fraction. The coefficient ξ accounted
for the fact that in the composite scintillator (as
distinct from single crystals) the space between the
scintillating substance (granules) was filled by non-
scintillating gel. The calculations were carried out for
gamma-radiation energies of 30 keV, 60 keV, 80 keV,
150 keV, 600 keV, and 8 MeV.
Fig.2 shows, as an example, the calculation re-
sults for thermal neutron detection efficiency εth for
a set of composite scintillators Ce:GSO. Calculations
were carried out separately for each of three energy
ranges. Unfilled signs in Fig.3 show εth values for
Ce:GSO single crystals of 0.39 mm thickness. Data
for the conversion electron detection range are noted
by squares, for the 77 keV peak – triangles, and for
their total signal – circles. The calculated curves
of gamma-radiation detection efficiency εγ are pre-
sented as solid lines.
We have compared the values of thermal neutron
detection efficiency calculated by formula (1) using
the obtained experimental data (internal counting)
and detection efficiency of external gamma-radiation
photons εγ , which were calculated by formula (2).
0,01 0,1 1
0,0
0,2
0,4
0,6
0,8
1,0
0,01 0,1 1
0,0
0,2
0,4
0,6
0,8
1,0
Detector Thickness (mm)
6
5
4
3
2
Ef
fic
ie
nc
y
of
n
eu
tro
n
de
te
ct
io
n
e th
1 ® Eg = 30 keV
2 ® Eg = 60 keV
3 ® Eg = 80 keV
4 ® Eg = 150 keV
5 ® Eg = 600 keV
6 ® Eg = 8000 keV
Ef
fic
ie
nc
y
of
g
am
m
f d
et
ec
tio
n
e g
1
20-120 keV56-120 keV,20-55 keV,
Fig.2. Thermal neutron detection efficiency εth for
a set of composite scintillators Ce:GSO (signs) and
calculated detection efficiency εγ of gamma-radiation
of energy Eγ (lines) as function of detector thickness
d
As it can be seen from Fig.2, the detection efficiency
of 33 keV conversion electrons (squares) is weakly de-
pendent upon the scintillator thickness. This results
becomes clear if we take into account that the free
path of 33 keV electrons in a given scintillation mate-
rial is approximately equal to 0.002 mm [13]. There-
fore, a single-layer composite gadolinium-containing
scintillator with average Ce:GSO or Ce:GPS granule
size above 0.002 mm is already an efficient selective
detector of conversion electrons of 33 keV energy.
The detection efficiency of external gamma-radiation
photons in this case becomes lower as compared with
detection efficiency of secondary radiations emerging
inside the granules, and substantial passive protec-
tion from external gamma-radiation photons becomes
redundant.
2.3. Combined neutron detectors
Using the broad possibilities of the proposed techno-
logical approach, we have developed new combined
92
composite detectors for separate detection of fast
and thermal neutrons on the background of gamma-
radiation. These detectors are composed of an or-
ganic composite scintillator that detects fast neu-
trons and a single-layer inorganic composite scintilla-
tor that detects thermal neutrons [5].
2.4. Detectors of alpha particles
The proposed technological approach to prepara-
tion of composite scintillation materials can also be
used for those materials which cannot be grown from
the melt as bulky crystals. Fig.3 shows amplitude
scintillation spectra of a single-layer composite scin-
tillator on the basis of 1,4-diphenyl-1,3-butadiene
excited by alpha-particles of different energies.
100 200 300 400 500
0
200
400
600
800
1000
1200
1400
2000 4000 6000 8000 10000
Number of Photons
4
5 6
7
32
Alpha Energies
E
a
(MeV)
1 0.65
2 1.44
3 2.16
4 2.71
5 3.29
6 3.87
7 4.43
1,4-diphenyl-2,3-butadiene Single-layer composite
detector (thin crystalline
plates)
N
um
be
r o
f p
ul
se
s
Channel Number
1
Fig.3. Amplitude scintillation spectra of single-layer
composite scintillator on the basis of 1,4-diphenyl-1,3-
butadiene in detection of alpha-particles of energies
0.65 MeV, 1.44 MeV, 2.16 MeV, 2.71 MeV, 3.29 MeV,
3.87 MeV and 4.43 MeV (239Pu)
Alpha-particles of different energies were ob-
tained by their moderation in air. The energy
of alpha-particles passed through the air layer
of thickness h was determined in the following
way. Knowing the alpha-particle path in air
r, we find the residual path ∆ = (r–h), and
then, using literature data [14], we determine
the energy corresponding to the residual path ∆.
0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0
0
1x103
2x103
3x103
4x103
5x103
6x103
o-POPOP
Single-layer o-POPOP
composite detector,
L = 1,3-1,5 mm
N
um
be
r o
f p
ho
to
ns
P
Alpha Energy E
a
, MeV
Fig.4. small Scintillation signal as function of ex-
citation energy (alpha-excitation, scintillators based
on o-POPOP)
Amplitude scintillation spectra of scintillators
based on o-POPOP, stilbene and 1,4-diphenyl-1,3-
butadiene obtained under irradiation by alpha-
particles of different energies were rather similar and
showed no peculiar features.
Figs.4 and 5 show scintillation signals from
composite scintillators based on o-POPOP and
1,4-diphenyl-1,3-butadien as function of excita-
tion energy for the case of alpha particles.
0,0 0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0
0
1x103
2x103
3x103
4x103
5x103
6x103
1,4-diphenyl-2,3-butadiene
Single-layer composite
detector (thin DFB
crystalline plates)
N
um
be
r o
f p
ho
to
ns
P
Alpha Energy E
a
, MeV
Fig.5. Scintillation signal as function of excita-
tion energy (alpha-excitation, scintillators based on 1,4-
diphenyl-1,3-buradiene)
3. SAMPLE PREPARATION
TECHNOLOGY FEATURES
3.1. Light transmission in the systems
studied
Composite scintillators are distinguished, as com-
pared to conventional systems, by their universality
and much broader application possibilities. Proper-
ties of known scintillators are generally characterized
by two main groups of parameters: 1–volume (ac-
counting for shape); 2–chemical composition. In the
case of composite scintillators, the third group of pa-
rameters becomes important, related to the size of
scintillation granules. Therefore for short-range radi-
ations, accounting for transparence features of these
systems, thin-layered samples shouls be developed.
For penetrating radiations, such as fast neutrons, op-
timal number of layers should be determined. This
number should be sufficiently high to ensure efficient
interaction and sufficiently low to ensure light out-
put from the scintillator. Thus, for detection of fast
neutrons the optimum thickness was determined as
20 mm (see Chapter 2.1), while for thermal neu-
trons – single-layered systems with granule size of
30-100 microns. In this respect, it is important to
study the transparence characteristics of composite
scintillators as function of thickness.
Since light propagation in such systems is of
diffuse character, it is reasonable to study trans-
parence as function of average granule size at dif-
ferent wavelengths. This is very important for de-
velopment of layered systems, where radiation detec-
tion efficiency is directly dependent on light transmis-
93
sion through the scintillator. Measurements of opti-
cal transmission for single-layered and multi-layered
stilbene-based samples were carried out using a Shi-
madzu 2450 spectrophotometer with an integrating
sphere. The spectral measurement range was from
300 to 700 nm. The results obtained show that
for composite scintillators based on crystalline gran-
ules of stilbene there is strong light absorption at
360 nm, while the material was practically trans-
parent at 700 nm. The intensity of light transmit-
ted through the composite scintillator is decreased
with higher thickness, which is related to an increase
in the number of layers of light-scattering granules.
0,5 1,0 1,5 2,0 2,5 3,0 3,5 4,0 4,5 5,0
1x103
2x103
3x103
4x103
5x103
6x103
7x103 single crystal
30 mm 3mm
N
um
be
r o
f p
ho
to
ns
P
Average grain size L
av
, mm
alpha particles
239Pu
Fig.6. Number of light photons as function of the
average size of crystalline stilbene granules for multi-
layered composite scintillators ⊘ 30 mm × 20 mm
(circles) and single-layered composite scintillators
⊘ 30 mm (squares)
The transparence dependence on the average
granule size is of the same character as the similar
dependence of the number of photons. For single-
layer systems practically no effect of the grain size
is observed, while for multi-layered systems smaller
granule size, which means larger contribution from
the scattering boundaries, both scintillation signal
and transmission are decreased, which should be
accounted for in development of multi-layered scin-
tillators [8, 15, 16].
3.2. Detectors with unlimited size of the
input window
The main advantage of composite scintillators, as
compared with structurally perfect organic single
crystals, is the possibility to create radiation detec-
tors with no limitations on the input window size
and shape. For scintillators of large area, a problem
emerges due to possible non-uniformity of the light
signal obtained in irradiation of different points of
the scintillator surface. For our studies, we chose,
as an example, composition detectors of diameter
200 mm. This size was considered as sufficient for
check-up of uniformity of scintillation characteristics
[17]. The scatter of relative light output values mea-
sured in different regions of composite scintillator of
200 mm diameter did not exceed 1%, i.e., less than
the standard 5% error of light output measurements.
Thus, it can be concluded that our proposed chain of
technological procedures allows preparation of uni-
form composite detectors with large output windows.
Technological preparation procedures of composite
scintillators impose no limitations on the area and
shape of the input window; however, such limita-
tions can be due to other factors, e.g., conditions
of transportation and assembling of the detector.
CCoonnnneeccttiioonn
lliinnee
Fig.7. Connection of separate parts of the composite
scintillator
Fig.7 shows an approach to this problem. First, sam-
ples of smaller size are fabricated, which are then
glued together by a non-scintillating dielectric gel.
The connection line is indicated by arrow [16].
3.3. Technological features of preparation of
composite scintillators for different
applications.
Our technology allows introduction of granules of any
nature into a binding base. Thus, application pos-
sibilities of composite scintillators for different tasks
are probably the highest as compared with other scin-
tillation systems.
The technological chain for preparation of com-
posite scintillation materials on the basis of crys-
talline granules of stilbene and p-terphenyl (Fig.8,
path I) was the first step in creation of new scin-
tillation materials [1, 18, 19]. We have noticed that
properties of the obtained composite scintillators are
weakly dependent upon structural perfectness of the
initial organic crystals. We made an attempt to make
the fabrication process of organic scintillators cheaper
and simpler, taking stilbene single crystals as exam-
ple (see Fig.8, path II).
The most energy-consuming and expensive stage
of preparation of composite scintillators is the pro-
cess of growth of structurally perfect single crystals.
For single crystal growth, preliminary purification of
the raw material is carried out by method of direc-
tional crystallization. The primary crystal obtained
has rather large number of defects, and such sample
cannot be directly used as a bulky single crystalline
scintillator. In preparation of crystalline granules by
cryogenic fragmentation, the primary crystal is frag-
mented over the defects into many micro-single crys-
tals.
94
Calculated values of the local field strength Eloc created by the pair of polaron states M−
p and M+
p in
anthracene crystal
Technological Sample based on granules Sample based on granules
operations of grown single crystal of primary crystal
Raw material purification by 168 168
directional crystallization, hours
Preparation of ampoule with 7 –
raw material for growth, hours
Single crystal growth*, hours 240 –
Fragmentation at low temperature, hours 1.5 1.5
Preparation of scintillator (selection
of fractions, introduction into binder 61 61
and binder polymerization), hours
Total, hours 477,5 230,5
* For single crystal sample of 20 mm diameter and 10 mm height. With larger volume of required raw material,
the difference between the required rime by two methods increases.
The obtained granules were separated into fractions
of different sizes, and composite scintillators were fabri-
cated using technological procedures worked out in our
studies. I.e., with our approach, we can obtain composite
scintillators omitting the stage of growing single crystals
of high structural perfectness. Duration of technological
operations in preparation of organic scintillators is shown
in Table.
Our studies have shown that composite scintil-
lators prepared from crystalline granules of stilbene
obtained from the primary crystal (after raw mate-
rial purification by directional crystallization) have as
good scintillation characteristics as composite scintil-
lators prepared from granules obtained from a pre-
grown single crystal of high structural perfection [18].
Fig.8. Flow chart of technological chain for prepa-
ration of composite scintillators: I, II – on the basis
of crystalline granules of stilbene and p-terphenyl us-
ing traditional and modified (i.e., without stage of grow-
ing structurally perfect single crystal) technology, respec-
tively; III – on the basis of crystalline granules of gadolin-
ium silicate (Ce:GSO) or pyrosilicate (Ce:GPS) activated
by Ce
Path III in Fig.8 demonstrates technological opera-
tions of preparation of composite scintillators on the ba-
sis of crystalline granules of gadolinium silicate (Ce:GSO)
or pyrosilicate (Ce:GPS) activated by Ce [19]. Such scin-
tillators are efficient detectors of thermal neutrons (see
Chapter 2.2).
3.4. Possibility to use composite scintillators
under high radiation loads. Prospects of
increasing radiation stability of composite
scintillators.
With a new generation of accelerators, such as, e.g.,
LHC CERN (Switzerland), irradiation intensity of detec-
tors used in such installations has substantially increased.
Thus, for the end-cap hadronic calorimeter (Hadron End-
cap (He)) of CMS detector CMS (LHC CERN) they use
scintillation detecting plates (tiles), with some of them
located near the beam axis, where particle flux intensity
is high, and correspondingly high are the dose loads. Af-
ter 10 years of operation of CMS-detector, the total dose
reaches 10 Mrad at average dose rate 1 Mrad/year or
0.0001 Mrad/hour.
Therefore, there is a constantly growing interest in in-
creasing the radiation stability of scintillators. We have
made a first step in this direction. We obtained infor-
mation on radiation stability of materials that can be
used as a base for composite scintillators. These mate-
rials are industrially produced gels required for creation
of radiation-resistant detectors on their base [20]. This
justifies our search in this direction.
4. CONCLUSIONS
Analysis of the results obtained for scintillation charac-
teristics of composite scintillators allows us to make the
following conclusions:
1. We have developed composite scintillators com-
posed of crystalline granules introduced into an organo-
silicon base. The obtained scintillation materials are not
hygroscopic, non-combustible, have no technological limi-
tations on the size and shape of the input window. These
materials show selectivity to detected signals, good scin-
tillation characteristics, as well as high spatial uniformity
of the scintillation signal.
2. A procedure has been developed for connection
of separate parts of composite scintillators, which allows
fabrication of scintillators with really unlimited area of
the input window. This is achieved by connecting sepa-
rate parts in assembling the scintillator at location of its
application.
3. It has been shown that the developed technology
can be used not only for traditional organic scintillation
95
materials, but also for materials which cannot be grown
from the melt as bulky crystals.
4. The obtained information on radiation stability of
gel dielectric bases allows us to state that the use of such
materials for preparation of composite scintillators is one
of the promising directions in improvement of character-
istics of detecting devices.
ACKNOWLEDGEMENTS
This work was supported by the State Fund for Funda-
mental Research of Ukraine (project No. F58/06, ”The
effect of large radiation doses on scintillation and optical
properties of novel types of organic detectors”).
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ÊÎÌÏÎÇÈÖÈÎÍÍÛÅ ÑÖÈÍÒÈËËßÒÎÐÛ ÊÀÊ ÍÎÂÛÉ ÂÈÄ ÑÖÈÍÒÈËËßÖÈÎÍÍÎÃÎ
ÌÀÒÅÐÈÀËÀ
Í.Ë.Êàðàâàåâà
Äëÿ ðàäèîýêîëîãè÷åñêèõ çàäà÷ íàìè áûë ðàçðàáîòàí íîâûé âèä ñöèíòèëëÿöèîííîãî ìàòåðèàëà � êîìïîçèöè-
îííûå ñöèíòèëëÿòîðû, ñîñòîÿùèå èç äèýëåêòðè÷åñêîãî ãåëÿ â êà÷åñòâå îñíîâû, â êîòîðóþ âíåäðåíû ãðàíóëû
ñöèíòèëëèðóþùåãî âåùåñòâà. Ïîêàçàíî, ÷òî äàííûé ìàòåðèàë ìîæåò ñîçäàâàòüñÿ êàê íà îñíîâå îðãàíè÷åñêèõ,
òàê è íåîðãàíè÷åñêèõ ãðàíóë. Ïåðâûå ïîçâîëÿþò ñîçäàâàòü ýôôåêòèâíûå äåòåêòîðû áûñòðûõ íåéòðîíîâ ñî
ñòåïåíüþ ðàçäåëåíèÿ íåéòðîíîâ íà ôîíå ãàììà-èçëó÷åíèÿ, áëèçêîé ê îðãàíè÷åñêèì ìîíîêðèñòàëëàì. Âòîðûå
ÿâèëèñü ýôôåêòèâíûìè äåòåêòîðàìè òåïëîâûõ íåéòðîíîâ, à âàðüèðîâàíèå ðàçìåðîâ èõ ãðàíóë ïîçâîëèëî ñó-
ùåñòâåííî óìåíüøèòü âëèÿíèå ôîíîâûõ èçëó÷åíèé. Îòäåëüíûå ôðàãìåíòû ñöèíòèëëÿòîðà ìîæíî ñîåäèíÿòü
âìåñòå, ñîçäàâàÿ áåñêîíå÷íûå ïëîñêîñòè. Âîçìîæíîñòü âûáîðà áîëåå ðàäèàöèîííî-ñòîéêèõ îñíîâ, ÷åì ñòàí-
äàðòíûå ñöèíòèëëÿöèîííûå îñíîâû, è ëþáûõ ñöèíòèëëÿöèîííûõ âåùåñòâ äëÿ ñîçäàíèÿ ãðàíóë ïîçâîëÿåò çà-
äóìàòüñÿ î âîçìîæíîñòè èñïîëüçîâàíèÿ òàêîãî òåõíîëîãè÷åñêîãî ïîäõîäà íå òîëüêî äëÿ çàäà÷ ðàäèîýêîëîãèè
(ñâåðõìàëûå ïîòîêè), íî è äëÿ çàäà÷ ôèçèêè âûñîêèõ ýíåðãèé.
ÊÎÌÏÎÇÈÖIÉÍI ÑÖÈÍÒÈËßÒÎÐÈ ßÊ ÍÎÂÈÉ ÂÈÄ ÑÖÈÍÒÈËßÖIÉÍÎÃÎ
ÌÀÒÅÐIÀËÓ
Í.Ë.Êàðàâà¹âà
Äëÿ ðàäiîåêîëîãi÷íèõ çàäà÷ íàìè áóâ ðîçðîáëåíèé íîâèé âèä ñöèíòèëÿöiéíîãî ìàòåðiàëó � êîìïîçèöiéíi ñöèí-
òèëÿòîðè, ùî ñêëàäàþòüñÿ ç äiåëåêòðè÷íîãî ãåëþ â ÿêîñòi îñíîâè, â ÿêó ââåäåíi ãðàíóëè ñöèíòèëþþ÷î¨ ðå÷î-
âèíè. Ïîêàçàíî, ùî äàíèé ìàòåðiàë ìîæå ñòâîðþâàòèñÿ ÿê íà îñíîâi îðãàíi÷íèõ, òàê i íåîðãàíi÷íèõ ãðàíóë.
Ïåðøi äîçâîëÿþòü ñòâîðþâàòè åôåêòèâíi äåòåêòîðè øâèäêèõ íåéòðîíiâ ç ñòóïåíåì ïîäiëó íåéòðîíiâ íà ôîíi
ãàììà- âèïðîìiíþâàííÿ, áëèçüêîþ äî îðãàíi÷íèõ ìîíîêðèñòàëiâ. Äðóãi ¹ åôåêòèâíèìè äåòåêòîðàìè òåïëîâèõ
íåéòðîíiâ, à âàðiþâàííÿ ðîçìiðiâ ¨õ ãðàíóë äîçâîëèëî iñòîòíî çìåíøèòè âïëèâ ôîíîâèõ âèïðîìiíþâàíü. Îêðå-
ìi ÷àñòèíè ñöèíòèëÿòîðà ìîæíà ç'¹äíóâàòè ðàçîì, ñòâîðþþ÷è íåñêií÷åííi ïëîùi. Ìîæëèâiñòü âèáîðó áiëüø
ðàäiàöiéíîñòiéêèõ îñíîâ, íiæ ñòàíäàðòíi ñöèíòèëÿöiéíi îñíîâè, òà áóäü-ÿêèõ ñöèíòèëÿöiéíèõ ðå÷îâèí äëÿ ñòâî-
ðåííÿ ãðàíóë äîçâîëÿ¹ çàìèñëèòèñÿ ïðî ìîæëèâiñòü âèêîðèñòàííÿ òàêîãî òåõíîëîãi÷íîãî ïiäõîäó íå òiëüêè äëÿ
çàäà÷ ðàäiîåêîëîãi¨ (íàäñëàáêi ïîòîêè), à é äëÿ çàäà÷ ôiçèêè âèñîêèõ åíåðãié.
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