Semiconductor sensors for dosimetry of epithermal neutrons
Minimum energy of neutron to displace atoms in silicon crystals are equal to 200 eV. Due to this fact testing our p-i-n diodes under irradiation by the epithermal neutrons was carried out. The more advanced p-i-n diodes on the base of high purity silicon were used at present work, and, as a result,...
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України
1999
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| Cite this: | Semiconductor sensors for dosimetry of epithermal neutrons / P.G. Litovchenko, R. Moss, F. Stecher-Rasmussen, K. Appelman, L.I. Barabash, T.I. Kibkalo, V.F. Lastovetsky, A.P. Litovchenko, M.B. Pinkovska // Semiconductor Physics Quantum Electronics & Optoelectronics. — 1999. — Т. 2, № 2. — С. 90-91. — Бібліогр.: 4 назв. — англ. |
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nasplib_isofts_kiev_ua-123456789-1190672025-02-09T17:22:50Z Semiconductor sensors for dosimetry of epithermal neutrons Litovchenko, P.G. Moss, R. Stecher-Rasmussen, F. Appelman, K. Barabash, L.I. Kibkalo, T.I. Lastovetsky, V.F. Litovchenko, A.P. Pinkovska, M.B. Minimum energy of neutron to displace atoms in silicon crystals are equal to 200 eV. Due to this fact testing our p-i-n diodes under irradiation by the epithermal neutrons was carried out. The more advanced p-i-n diodes on the base of high purity silicon were used at present work, and, as a result, we have obtained considerably more sensitive sensors for more wide range of neutron doses. The sensitivity of sensors is 0.14 V/Gy for average neutron energy of 24 keV. 1999 Article Semiconductor sensors for dosimetry of epithermal neutrons / P.G. Litovchenko, R. Moss, F. Stecher-Rasmussen, K. Appelman, L.I. Barabash, T.I. Kibkalo, V.F. Lastovetsky, A.P. Litovchenko, M.B. Pinkovska // Semiconductor Physics Quantum Electronics & Optoelectronics. — 1999. — Т. 2, № 2. — С. 90-91. — Бібліогр.: 4 назв. — англ. 1560-8034 PACS 29.40.Wk https://nasplib.isofts.kiev.ua/handle/123456789/119067 en Semiconductor Physics Quantum Electronics & Optoelectronics application/pdf Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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Minimum energy of neutron to displace atoms in silicon crystals are equal to 200 eV. Due to this fact testing our p-i-n diodes under irradiation by the epithermal neutrons was carried out. The more advanced p-i-n diodes on the base of high purity silicon were used at present work, and, as a result, we have obtained considerably more sensitive sensors for more wide range of neutron doses. The sensitivity of sensors is 0.14 V/Gy for average neutron energy of 24 keV. |
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Litovchenko, P.G. Moss, R. Stecher-Rasmussen, F. Appelman, K. Barabash, L.I. Kibkalo, T.I. Lastovetsky, V.F. Litovchenko, A.P. Pinkovska, M.B. |
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Litovchenko, P.G. Moss, R. Stecher-Rasmussen, F. Appelman, K. Barabash, L.I. Kibkalo, T.I. Lastovetsky, V.F. Litovchenko, A.P. Pinkovska, M.B. Semiconductor sensors for dosimetry of epithermal neutrons Semiconductor Physics Quantum Electronics & Optoelectronics |
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Litovchenko, P.G. Moss, R. Stecher-Rasmussen, F. Appelman, K. Barabash, L.I. Kibkalo, T.I. Lastovetsky, V.F. Litovchenko, A.P. Pinkovska, M.B. |
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Litovchenko, P.G. |
| title |
Semiconductor sensors for dosimetry of epithermal neutrons |
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Semiconductor sensors for dosimetry of epithermal neutrons |
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Semiconductor sensors for dosimetry of epithermal neutrons |
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Semiconductor sensors for dosimetry of epithermal neutrons |
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Semiconductor sensors for dosimetry of epithermal neutrons |
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semiconductor sensors for dosimetry of epithermal neutrons |
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Інститут фізики напівпровідників імені В.Є. Лашкарьова НАН України |
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1999 |
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https://nasplib.isofts.kiev.ua/handle/123456789/119067 |
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Semiconductor sensors for dosimetry of epithermal neutrons / P.G. Litovchenko, R. Moss, F. Stecher-Rasmussen, K. Appelman, L.I. Barabash, T.I. Kibkalo, V.F. Lastovetsky, A.P. Litovchenko, M.B. Pinkovska // Semiconductor Physics Quantum Electronics & Optoelectronics. — 1999. — Т. 2, № 2. — С. 90-91. — Бібліогр.: 4 назв. — англ. |
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Semiconductor Physics Quantum Electronics & Optoelectronics |
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90 © 1999, Institute of Semiconductor Physics, National Academy of Sciences of Ukraine
Semiconductor Physics, Quantum Electronics & Optoelectronics. 1999. V. 2, N 2. P. 90-91.
PACS 29.40.Wk
Semiconductor sensors for dosimetry of
epithermal neutrons
P. G. Litovchenko1, R. Moss2, F. Stecher-Rasmussen2, K. Appelman2, L. I. Barabash1,
T. I. Kibkalo1, V. F. Lastovetsky1, A. P. Litovchenko1, M. B. Pinkovska1.
1 SC Institute for Nuclear Research of NASU, 47 prospect Nauki, 252028 Kiev, Ukraine.
2 ECN, Westerduinweg 3, P. O. Box 1,1755 ZG Petten, The Netherlands.
Abstract. Minimum energy of neutron to displace atoms in silicon crystals are equal to 200 eV.
Due to this fact testing our p-i-n diodes under irradiation by the epithermal neutrons was carried
out. The more advanced p-i-n diodes on the base of high purity silicon were used at present work,
and, as a result, we have obtained considerably more sensitive sensors for more wide range of
neutron doses. The sensitivity of sensors is 0.14 V/Gy for average neutron energy of 24 keV.
Keywords: dosimetry, semiconductor detectors, epithermal neutrons, silicon, converter.
Paper received 17.05.98; revised manuscript received 26.06.98; accepted for publication 12.07.98.
1. Introduction
The measurement of epithermal neutron flux is very signifi-
cant task for Boron Neutron Capture Therapy (BNCT). In
this paper semiconductor sensors were used for epithermal
neutron flux measurement. These semiconductor sensors
were produced by us. These are p-i-n diodes and semicon-
ductor detectors with 235U converter.
Possibilities for application of fast neutron dosime-
ters using the p-i-n diodes as a base have been shown
earlier [1]. The principle of detection is based on the cre-
ation of radiation defects in semiconductors under the
influence of fast neutrons, which change the electrical
parameters (a diode voltage drop increases for a fixed
current). It is known that the minimum energy of neu-
tron to displace atoms in silicon crystals is equal to
~ 200 eV. Due to this fact there were all reasons to test
the p-i-n diodes prepared by us under irradiation in the
epithermal neutron energy range.
2. Experimental results
At the beginning of investigation, our colleagues and we
have made the detail analysis of all available dates, such
as the KERMA damage and the total KERMA for silicon [2].
The results of experimental verification for monoenergetic
neutrons in the energy range from 90 to 900 keV were ob-
tained in [2]. In spite of the complicated view of the KERMA
damage dependence, as evident from these data, a proper
coincidence between the experimental results and theoreti-
cal calculations of KERMA by Monte Karlo method was
obtained. The presence of some hollow in the neutron ener-
gy range from 100 to 300 eV partly makes difficulties to use
the p-i-n diodes as tissue-equivalent sensors in practically
used energy range of epithermal neutrons. There is doubt-
less interest to test the offered by us semiconductor sen-
sors intended for measurements of total tissue dose from
the extremely complicated spectrum of Petten High Flux Re-
actor, which was used in BNCT [3]. From these data, the fast
neutrons (>10keV) make a considerable and undesirable
contribution to damage KERMA. In our work [4], it was
shown that p-i-n diodes, which were calibrated with a known
energy, could be used to determine tissue doses, received in
the courses of irradiation by neutrons with an unknown
energy. Proceeding from this fact, we were able to determine
a sensitivity of our sensors under the energy of 24 keV (the
channel HB12) and intensity of 1.23.1012 n/m2.sec.
The changes of a direct voltage drop (∆V) for p-i-n di-
odes under fixed current of 1mA (at irradiation time 85 min,
P.G. Litovchenko et al.: Semiconductor sensors for dosimetry of...
91SQO, 2(2), 1999
En = 24 keV, tissue KERMA 1Gy = 5.1015 n/m2) were mea-
sured. The average changes of the direct voltage drop is
∆V = 0.175 V and the received dose is Φ = 1.25 Gy. The
average sensitivity of sensors was ∆V/Φ = 0.140 V/Gy.
Dose dependences of ∆V were obtained by means of
additional irradiation of the same diodes up to the total
16 hours. Dose dependencies are presented in Fig. 1 for
the sensors of numbers 2n and 3n with the best and the
worst sensitivities, respectively. As one can see from
Fig. 1, the changes of a direct voltage drop are very good
fits to linear dependence ∆V vs Φ in the range of used
irradiation doses.
Mentioned sensors were calibrated in the channel
HB12, and then irradiated in the channel HB11 for
1.8.103sec. Our sensors give the average tissue dose of
neutrons as much as Φ = (2.76±0.16)Gy per hour.
In this channel, besides neutrons, the gamma irradiation
is presents, according to the HB11 channel technical char-
acteristics, and gives the contribution to dose 1.2 Gy per
hour. As the coefficient of discrimination for our neutron
sensors in relation to the gamma irradiation is ~103 [2], then
the determined above tissue dose entirely relates to the neu-
tron spectrum of the channel HB 11. Proceeding from the
HB11 technical characteristics one may appreciate the share
of fast and epithermal neutrons into tissue KERMA. The
epithermal neutron flux (0,414 eV-10 keV) is 3.3.1012 n/m2sec.
If we suppose that all neutrons in this spectrum possess the
energy as much as 10 keV (KERMA = 1016 n/m2), then the
dose will correspond to Φ = 1.2 Gy per hour. Under assump-
tion that both the average energy and flux of fast neutrons are
0.5MeV(KERMA = 5.6.108), and 4.7.107n/cm2/s (>10keV)
respectively, we obtained Φ = 1.6 Gy. These appraisals of
ours coincide with obtained by us results on the total dose
(1.6+1.2)=2.8 Gy and confirm an undesirable contribution of
fast neutrons (60%) in the total theraputical dose.
The epithermal neutron flux at the HB11 channel was
measured also by the silicon barrier-surface detectors with
an attached 235U converter. The converter as 235U oxide-
protoxide being enriched up to 99.92 % with the thickness of
1.5.10-4 m, mass 10-6 kg and alpha activity of 81 Bq was
fabricated on Al- sublayer. We established that the detec-
tors efficiency to epithermal neutrons the (HB11 neutron
spectrum) is 1.82.10-5imp/n.
Conclusions
The use of p-i-n diodes made on the base of high purity
silicon for registration of epithermal neutrons with the
coefficient of gamma ray discrimination 103 is demon-
strated. A good agreement of experimental data with
theoretical calculations of the damage KERMA for sili-
con has been shown.
It is shown that p-i-n diodes can serve as tissue-equiv-
alent dosimeters in the neutron energy range from 300 eV till
30 keV. The possibility of neutron flux monitoring by means
of silicon detectors with 235U converter was shown.
References
1. A. B. Rosenfeld, L. I.Barabash, P. G. Litovchenko, V. I. Khivrich,
P-i-n Diode with a Wide Measurement Range of Fast Neutron Dos-
es., Rad. Prot. Dos., 33(l/4), pp. 175-178 (1990).
2. M. G. Carolan, A. B. Rosenfeld, S. Wallace, H. Mariaty,
G. J. Storr, V. I. Khivrich, R. Moss, B. J. Alien, Silicon Dosime-
ter Diode for BNCT Using Epithermal Neutron Sources. Proc. of
1-st Intern. Workshop on Accelerator-Based Neutron Sources for
BNCT, l, September 11-14, 1994, Jacson, Wyoming, pp. 299-309.
3. Boron Neutron Capture Therapy, Proc. of Intern. Workshop and
plenary meeting, Petten The Netherlands, 1991, Edited by
D. Gabel and R. Moss, p.47.
4. V. I. Khivrich, M. D. Varentsov, P. G. Litovchenko, A. I. Ano-
khin, A. B. Rosenfeld, M. G. Carolan, O. S. Zinets, M. I. Rein-
hard, D. Alexiev, High Purity Silicon as a Basic Material for Man-
ufacturing of Radiation Defects and Integral Neutron Dosimeters,
IEEE Trans. on Nucl. Sci., NS-43, N6, pp. 2687-2692 (1996).
Fig. 1. Dose dependence as a function of change of voltage (∆V) at
p-i-n diodes with big (2n) and little (3n) sensitivity under irradiation
of neutron with energy of 24 keV.
1 10
1 10
1 1
0.1 0.1
ΦΦΦΦΦ, Gy
∆∆∆∆ ∆V
,
V
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