Sensitivity studies of beta-radiation detector based on small-crystalline scintillator ZnSe(Te)
A new large area β-detector has been designed and studied. The design includes wedge-shaped light transducers. A composite material based on a small crystalline ZnSe(Te) was applied onto the wide surface of light transducer. This design ensures optimum light collection from the large sensitive surfa...
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| Date: | 2001 |
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Національний науковий центр «Харківський фізико-технічний інститут» НАН України
2001
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| Cite this: | Sensitivity studies of beta-radiation detector based on small-crystalline scintillator ZnSe(Te) / V. Gavrylyuk, L. Gal’chinetskyi, E. Danshin, O. Zelenskaya, K. Katrunov, V. Ryzhikov, N. Starzhynskyi, V. Chernikov // Вопросы атомной науки и техники. — 2001. — № 3. — С. 167-170. — Бібліогр.: 4 назв. — англ. |
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Digital Library of Periodicals of National Academy of Sciences of Ukraine| _version_ | 1859673133162692608 |
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| author | Gavrylyuk, V. Gal’chinetskyi, L. Danshin, E. Zelenskaya, O. Katrunov, K. Ryzhikov, V. Starzhynskyi, N. Chernikov, V. |
| author_facet | Gavrylyuk, V. Gal’chinetskyi, L. Danshin, E. Zelenskaya, O. Katrunov, K. Ryzhikov, V. Starzhynskyi, N. Chernikov, V. |
| citation_txt | Sensitivity studies of beta-radiation detector based on small-crystalline scintillator ZnSe(Te) / V. Gavrylyuk, L. Gal’chinetskyi, E. Danshin, O. Zelenskaya, K. Katrunov, V. Ryzhikov, N. Starzhynskyi, V. Chernikov // Вопросы атомной науки и техники. — 2001. — № 3. — С. 167-170. — Бібліогр.: 4 назв. — англ. |
| collection | DSpace DC |
| container_title | Вопросы атомной науки и техники |
| description | A new large area β-detector has been designed and studied. The design includes wedge-shaped light transducers. A composite material based on a small crystalline ZnSe(Te) was applied onto the wide surface of light transducer. This design ensures optimum light collection from the large sensitive surface onto the output window of a much smaller size. An experimental specimen has been prepared, which showed a β-sensitivity Cβ=5.5 cm². The spectrograms of a ⁹⁰Sr+⁹⁰Y β-source obtained with the specimen under study make it possible to evaluate the age of the source by the ratio of low- and high-energy regions of the spectrum. Other designs are proposed for application of large-area detectors possessing wedge-shaped light transducers as elements of assembled constructions for high efficiency detectors operating under flow conditions.
|
| first_indexed | 2025-11-30T14:33:38Z |
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SENSITIVITY STUDIES OF BETA-RADIATION DETECTOR BASED
ON SMALL-CRYSTALLINE SCINTILLATOR ZNSE(TE)
V. Gavrylyuk, L. Gal’chinetskyi, E. Danshin, O. Zelenskaya, K. Katrunov,
V. Ryzhikov, N. Starzhynskyi, V. Chernikov
STC for Radiation Instruments
Concern “Institute for Single Crystals” of the National Academy of sciences of Ukraine
60 Lenin Ave., 61001, Kharkov, Ukraine
e-mail: stcri@isc.kharkov.com
A new large area β- detector has been designed and studied. The design includes wedge-shaped light transducers. A
composite material based on a small crystalline ZnSe(Te) was applied onto the wide surface of light transducer. This
design ensures optimum light collection from the large sensitive surface onto the output window of a much smaller
size. An experimental specimen has been prepared, which showed a β-sensitivity Cβ=5.5 cm2. The spectrograms of a
90Sr+90Y β-source obtained with the specimen under study make it possible to evaluate the age of the source by the
ratio of low- and high-energy regions of the spectrum. Other designs are proposed for application of large-area de-
tectors possessing wedge-shaped light transducers as elements of assembled constructions for high efficiency detec-
tors operating under flow conditions.
PACS numbers: 29.40.-n, 07.77
1 INTRODUCTION
Solid-state scintillation detectors (SD) comprising
scintillation crystals (S) and silicon PIN photodiodes
(Si-PIN-PD) are widely used in dosimeters, radiometers,
spectrometers, in technological equipment for medical
diagnostics, environment monitoring, customs and secu-
rity control, etc [1].
Detectors comprising PD have many advantages as
compared with those based on PMT. PMT have the nar-
rower dynamic range of the measured radiation levels,
their amplification rate is not stable, and the output sig-
nal is rather sensibly temperature-dependent (~1 %/ K).
Besides this, low voltage power supply of PD ensures
its functioning in extreme conditions (including dangers
of explosions, fire, etc.), and small size of PD-based de-
tectors allows their use in portable instruments.
One of factors limiting the broad use of “scintillator-
photodiode” detectors is a small area of the photosensi-
tive surface of the photodiode (S ~ 1 cm2). This disad-
vantage can be partially removed by the use of crystals
with a large sensitive volume. However, this leads to
“hanging over” of the scintillator above the PD input
window, which leads to noticeable deterioration of the
signal at the detector output.
Up to date, for detection of beta-radiation the most
widely used scintillators were p-terphenyl, CsI(Tl),
NaI(Tl). However, alkali halide crystals are hygroscop-
ic, that requires their additional protection against mois-
ture. Operation under conditions of high humidity leads
to deterioration of the crystal surface, a “dead layer” is
formed, and detector characteristics are subsequently
changed. Crystals of p-terphenyl have bad spectral
matching with the Si-photodiode, and they can be used
only in combination with PMT.
A promising scintillator for beta-radiation detection
is ZnSe(Te), which has a high conversion efficiency
(η = 18 %) [2], high spectral matching coefficient with
Si-photodiode (F = 91 %) [3], and is not hygroscopic.
However, the existing technological processes do not al-
low obtaining ZnSe(Te) single crystals larger than 3 cm
in diameter. Detector sensitivity can be increased with
larger area of the output window and creation of opti-
mum light collection conditions in the scintillator. One
of the ways to increase the sensitive detector area is cre-
ation of a detecting layer as a conglomerate of scintillat-
ing ZnSe(Te) grains in a transparent dispersion medium
located on the light transducer surface. Optimization of
light collection conditions in such a detector is related to
the choice of the optimum grain shape, the use of addi-
tional reflective coatings, and transparence of the dis-
persion medium surrounding the detector, as well as to
the optimum shape and size of the light transducer.
In this paper, we studied a possibility to increase the
sensitivity of beta-radiation detectors by means of a
scintillation monolayer formed by small-crystalline par-
ticles of ZnSe(Te) on light transducers of large area.
2 RESULTS AND DISCUSSION
In [4], a new design was proposed for a solid-state
scintillation detector, in which a conglomerate of small-
crystalline particles of ZnSe(Te) was used as a scintilla-
tor. The particles were dispersed in the polymer matrix
transparent to the intrinsic radiation of the scintillator.
Using computer modeling, we have carried out theoreti-
cal determination of the optimum shape of the scintilla-
tor crystal grains ensuring the best light collection. The
influence of the dispersion medium (optical adhesive)
on the light output value was also analyzed. It has been
shown that such a detector design leads to a higher de-
tection efficiency of beta- and low-energy gamma-radia-
tion as compared with solid single crystalline plates of
the same material. The area of the scintillation layer in
these detectors is technologically unlimited and can be
chosen according to specific application conditions.
However, as a rule, the light-sensitive area of the photo-
diode is small and does not exceed 1x1 cm2. At the same
time, obtaining higher sensitivity requires larger areas of
the scintillation layer. It becomes necessary to use a
ВОПРОСЫ АТОМНОЙ НАУКИ И ТЕХНИКИ. 2001. №3.
Серия: Ядерно-физические исследования (38), с. 167-170.
167
light transducer for transmission of the scintillation light
from the large area to the photoreceiver.
Using Monte-Carlo calculations, light collection co-
efficient was evaluated for different types of light trans-
ducers. Light reflection from the light transducer surface
on which scintillator grains were located was considered
as reflection from the boundary between media with re-
fraction indexes 1.5 and 2.57 (the light transducer and
ZnSe(Te) grain, respectively). When the light beam
comes into a grain, the probability of its returning back
into the light transducer was taken as 0.6 (this is the val-
ue of the light collection coefficient for the case of pyra-
mid-shaped grain with the angle of 60o between the
sides and the base of the pyramid). Direction of the light
beam coming into the light transducer was considered as
uniform in the space (isotropic source).
The light transducer efficiency was characterized by
the relationship
P S1 / S2 , (1)
where τ is the light collection coefficient, S1 is the area
occupied by the scintillator grains, and S2 is the area of
the light transducer output window.
The value of P shows by how many times the signal
from the matrix scintillator connected to the photore-
ceiver by the light transducer is larger than a similar sig-
nal for the case of scintillator grains applied directly
onto the photoreceiver.
As a result of our calculations, we have shown that
the most advantageous design of the light transducer is
achieved when it is wedge-shaped (Fig. 1).
а)
b)
Fig. 1. Small-crystalline ionizing radiation detector of large area: a) axonometric view, b) side view.
1 – dispersion polymeric matrix, 2 – scintillation monolayer of small-crystalline ZnSe(Te), 3 – input
window of the detector, 4 – output window of the detector, 5 – light transducer.
Fig. 2. Efficiency P of the wedge-shaped light transducer as a function of its dimensions – length H
and width l at the side opposite to the photoreceiver. The size of the output window S2 = 1 x 1 cm2.
With such a design, scintillator grains are applied
onto the largest area surface of the wedge. Light collec-
tion onto the photoreceiver is made from the backside of
the wedge. Optimization of the design consists in choos-
168
ing such values of the wedge length H and its width l at
the farthest end from the window that would ensure the
highest efficiency P as determined according to (1).
Fig. 2 shows the calculated two-dimensional depen-
dence of P on the mentioned geometric factors.
It follows from our calculations that a wedge-shaped
light transducer is 2-3 times more efficient than an ordi-
nary concentrating light transducer. It is important that
the area is practically not limited and should be related
only to the specific uses of a detector.
We have prepared experimental samples of the
large-area detector with a wedge-shaped light transducer
with scintillation layer in the form of crystalline parti-
cles of ZnSe(Te). The light transducer dimensions were:
output window area – S2 = 1x1 cm2; the area of the input
surface of the light transducer on which the crystalline
particles were placed – S1 = 40 cm2. This surface was
trapezium-shaped with bases 1 cm and 7 cm and height
10 cm. The light transducer was made of transparent
material – polystyrene. The light absorption coefficient
did not exceed 0.01 cm-1.
Measurements of the detector sensitivity in the
counting mode by measuring the output signal were car-
ried out by the pulse method using a set-up with a
charge-sensitive preamplifier. An S3590 Hamamatsu Si-
PIN-PD was connected to the input of the preamplifier.
From the output, the signal came to the input of a stan-
dard amplifier-shaper, and after that – to a frequency
meter. As a radiation source, we used a reference
90Sr+90Y beta-source with the active surface area of
160 cm2. The detector sensitivity to beta-radiation was
determined from the number of flashes (events) per sec-
ond under irradiation by the beta-source located directly
on the input surface of the detector.
The following expression was used for calculations:
,NNSС fcdet ⋅=β (2)
where Сβ is the detector sensitivity, cm2; Sdet is the area
of the input window of the detector, cm2; Nc is the num-
ber of recorded events per second; Nf is the number of
beta-particles falling onto the input window effective
surface, which can be presented as
( ) ,SeAK1KSN sour
Tt693.0
0bsfildetf
−⋅⋅−⋅= (3)
where A0 is the external radiation from the active layer
inside 2π angle, beta-particles per second; t is the age of
the source, years; T is the half-decay time, years; Ssour is
the active surface area of the source, cm2; Kfil ≈ 0.8 is
the filling coefficient of the detector working surface by
the scintillation material; Kbs ≈ 0.4 is the coefficient of
back scattering by scintillator material.
As a result of calculations, we obtained the sensitivi-
ty value Cβ = 5.5 cm2.
As material for wedge-shaped light transducer, a
polished single crystal CsI(Tl) was also used, which
showed good sensitivity to gamma-radiation of a 137Cs
source. This allows application of such detectors as
“phoswich” detectors for separate detection of gamma-
and beta-radiation.
In Fig. 3, the beta-spectrogram of a 90Sr+90Y source
is presented, which was obtained using a scintillation
spectrometer with the detector developed on the basis of
ZnSe(Te) and plastic scintillator (PS) of Ø 6.3x6.3 cm3
size. The spectrograms were recorded without passive
protection.
0 500 1000 1500 2000
0,0
0,2
0,4
0,6
0,8
1,0
3
2
3
2
1
d
N
/d
E,
re
l.u
n
Energy beta-radiation, keV
Fig. 3. Beta-spectrograms of a 90Sr+90Y source: 1 – calculated; 2 – obtained using plastic scintillator;
3 – obtained using ZnSe(Te).
PS-based scintillators in the high-energy region have
a “tail” from high-energy radiation of uranium-radium
and thorium series of the environment. As is seen from
Fig. 3, the closest, as for shape, to the calculated spec-
trogram is that obtained using a plastic scintillator. The
source chosen for measurements had equal quantities
per time unit of the forming and decaying daughter nu-
clei, i.e., an equilibrium is established between the num-
ber of “mother” and “daughter” nuclei. For ZnSe(Te)-
based detectors, the daughter nucleus contribution into
the counting rate is not significant, which is probably re-
lated to stronger (as compared with PS) reflection of the
particles from an inorganic scintillator with higher
atomic number than that of PS. The other reason could
be non-optimum thickness of ZnSe(Te) for this spectral
range. This difference in the spectrum shape can pre-
sumably be used to evaluate the age of the source, using
PS as light transducer.
Detectors with wedge-shaped light transducers can
be used as construction elements of flow combined de-
tector for radioactive liquids and gases. At least three
types of the design can be proposed:
1. With the shape of “flower with petals” (Fig. 4(a)) –
two-dimensional detector. 169
2. Shaped as a flow construction where each construc-
tion element is a blade of a fan-like system, with a
minimum number of petals – 4-5 (Fig. 4(b)).
3. Fan-like system, the number of petals not limited
(Fig. 4(c)).
Light collection for all the design variants is made
using a 1x1x1 cm3 light transducer, or a polyhedron of
the same volume upon the silicon photodiode with
1x1 сm2 input window area.
а) b)
c)
Fig. 4. Possible design variants of combined flow detectors: 1 – construction element of the detector as a small-
crystalline detector of large size; 2 – photodiode; 3 – scintillation layer of the detector element.
3 CONCLUSIONS
As a result of our work, a new combined detector
has been designed and studied, which had a large area
and used wedge-shaped light transducers. Onto the wide
light transducer surface, a composite material was ap-
plied based on small crystalline ZnSe(Te). Such design
ensures optimum light collection from the large sensi-
tive surface of the input window onto the output win-
dow of much smaller size. An experimental specimen
was made, for which sensitivity to 90Sr+90Y beta-source
was determined – a source with sensitivity of 5.5 cm2.
Replacing the light transducer material with PS or
CsI(Tl), it is possible to obtain “phoswich” detectors for
separate registration of charged particles and the back-
ground gamma-radiation. The spectrograms of a
90Sr+90Y beta-source obtained with the detector speci-
men under study make it possible to evaluate the age of
the source by the ratio of low- and high-energy regions
of the spectrum. Variants are proposed for application
of large-area detectors with wedge-shaped light trans-
ducers as elements of assembled constructions for high-
efficiency detectors operating under flow conditions.
4 ACKNOWLEGMENTS
Samples provided by V.Silin are gratefully acknowl-
edged.
This work is supported by the INTAS Grant
No 99-01348.
REFERENCES
1. L.V.Atroschenko, S.F.Burachas, L.P.Gal’chinetskii,
B.V.Grinev, B.D.Ryzhikov, N.G.Starginskii. Crys-
tals of scintillators and detectors of ionizing radia-
tions on their base. Kiev: “Naukova dumka”, 1998,
312 p.
2. K.A.Katrunov, L.P.Gal’chinetskii, B.D.Ryzhikov et
al. Determination of conversion efficiency of X-ray
luminophores in measurement of radiation rate //
Atomnaya Energiya. 1994, v. 76, No. 5, p. 428-431.
3. V.D.Ryzhikov, Yu.A.Borodenko, S.N.Galkin et.al.
Scintillation crystals ZnSe(Te): preparation, pro-
peties, applications.// Proc.Int.Conference «Inor-
ganic Scintillators and their Applications», 1995,
p. 465-468.
4. V.G.Volkov, V.P.Gavriluk, L.P.Gal’chinetskii et al.
Small-crystalline ionizing radiation detector based
on ZnSe(Te) // Pribory i Teknika Eksperimenta.
1999, No. 6, p. 37-42.
170
|
| id | nasplib_isofts_kiev_ua-123456789-79270 |
| institution | Digital Library of Periodicals of National Academy of Sciences of Ukraine |
| issn | 1562-6016 |
| language | English |
| last_indexed | 2025-11-30T14:33:38Z |
| publishDate | 2001 |
| publisher | Національний науковий центр «Харківський фізико-технічний інститут» НАН України |
| record_format | dspace |
| spelling | Gavrylyuk, V. Gal’chinetskyi, L. Danshin, E. Zelenskaya, O. Katrunov, K. Ryzhikov, V. Starzhynskyi, N. Chernikov, V. 2015-03-30T08:45:47Z 2015-03-30T08:45:47Z 2001 Sensitivity studies of beta-radiation detector based on small-crystalline scintillator ZnSe(Te) / V. Gavrylyuk, L. Gal’chinetskyi, E. Danshin, O. Zelenskaya, K. Katrunov, V. Ryzhikov, N. Starzhynskyi, V. Chernikov // Вопросы атомной науки и техники. — 2001. — № 3. — С. 167-170. — Бібліогр.: 4 назв. — англ. 1562-6016 PACS numbers: 29.40.-n, 07.77 https://nasplib.isofts.kiev.ua/handle/123456789/79270 A new large area β-detector has been designed and studied. The design includes wedge-shaped light transducers. A composite material based on a small crystalline ZnSe(Te) was applied onto the wide surface of light transducer. This design ensures optimum light collection from the large sensitive surface onto the output window of a much smaller size. An experimental specimen has been prepared, which showed a β-sensitivity Cβ=5.5 cm². The spectrograms of a ⁹⁰Sr+⁹⁰Y β-source obtained with the specimen under study make it possible to evaluate the age of the source by the ratio of low- and high-energy regions of the spectrum. Other designs are proposed for application of large-area detectors possessing wedge-shaped light transducers as elements of assembled constructions for high efficiency detectors operating under flow conditions. Samples provided by V.Silin are gratefully acknowledged. This work is supported by the INTAS Grant No 99-01348. en Національний науковий центр «Харківський фізико-технічний інститут» НАН України Вопросы атомной науки и техники Sensitivity studies of beta-radiation detector based on small-crystalline scintillator ZnSe(Te) Исследование чувствительности детекторов β–излучения на основе мелкокристаллического сцинтиллятора ZnSe(Te) Article published earlier |
| spellingShingle | Sensitivity studies of beta-radiation detector based on small-crystalline scintillator ZnSe(Te) Gavrylyuk, V. Gal’chinetskyi, L. Danshin, E. Zelenskaya, O. Katrunov, K. Ryzhikov, V. Starzhynskyi, N. Chernikov, V. |
| title | Sensitivity studies of beta-radiation detector based on small-crystalline scintillator ZnSe(Te) |
| title_alt | Исследование чувствительности детекторов β–излучения на основе мелкокристаллического сцинтиллятора ZnSe(Te) |
| title_full | Sensitivity studies of beta-radiation detector based on small-crystalline scintillator ZnSe(Te) |
| title_fullStr | Sensitivity studies of beta-radiation detector based on small-crystalline scintillator ZnSe(Te) |
| title_full_unstemmed | Sensitivity studies of beta-radiation detector based on small-crystalline scintillator ZnSe(Te) |
| title_short | Sensitivity studies of beta-radiation detector based on small-crystalline scintillator ZnSe(Te) |
| title_sort | sensitivity studies of beta-radiation detector based on small-crystalline scintillator znse(te) |
| url | https://nasplib.isofts.kiev.ua/handle/123456789/79270 |
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