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A new thermo-lumino neutron detector
ELSEVIER
Physica B 241 243 (1998) 127 129
A new t h e r m o - l u m i n o neutron detector M. Hidaka a'*, H. Akiyama b, H. Fujii c, H. Yoshizawa d, Y. Kawamura d, Y.
Fujii d
Department of Physics, Kyushu UniversiO,. Fukuoka 812-8l, Japan b Faculty ~fEducation, M~vazaki UniversiO,, Mo,azaki 889-21, Japan c Facul~ of Education. Oita University, Oita 870-11. Japan d Neutron Scattering LaboratotT. I.S.S.P.. Univ. of Tolg,o. Tokai, lbaraki 319- l 1, Japan
Abstract A new neutron diffraction detector has been developed, which utilizes the effect of thermoluminescence. The system is composed of a thermo-lumino sheet which functions as a neutron converter and a CCD camera. The thermo-lumino sheet is made by a complex of (I°B-BaSO4: Er, C1), while the CCD camera records the thermoluminescence from the sheet, yielding a two-dimensional visual image of neutron scattering. The thermo-lumino sheet is quite stable to various atmospheric conditions (temperature, humidity, illumination, and external strain), and can be repeatedly used after annealing. ~" 1998 Published by Elsevier Science B.V. All rights reserved. Kevwords: Detectors; Imaging; Thermoluminescence
1. Introduction A neutron diffraction camera is a convenient tool and has some advantages over an ordinary counter system in order to observe the diffraction patterns in the two-dimensional reciprocal space. For a camera method, a sheet of 6LiF + ZnP(Ag) which sandwich an X-ray film has been used as a neutron scintillator. The X-ray film was, however, not efficient to obtain quantitative data of the reflections because of its poor dynamic range of neutron intensity. We have been attempting to develop an alternative film-type detector which is simple to handle and whose production cost is inexpensive. In the
* Corresponding author.
present paper, we will report the newly developed detector system for neutron diffraction.
2. Experimental In order to obtain the visual image of neutron diffraction, we employed thermal luminosity of defective poly-crystalline compound to the present neutron detector [1]. As a material for a neutron converter, we empirically chose a phospher complex doped with a few rare-earth ions; (l°B BaSO4: Er, C1). The a particles emitted from 1°B through a (n, a) reaction activate the thermal luminosity of the phospher complex. The phospher complex was lapped by Teflon sheets into a binder shape. We called it a thermo-lumino sheet (TLS).
0921-4526/98/$19.00 ~' 1998 Published by Elsevier Science B.V. All rights reserved PII S092 1- 4 5 2 6 ( 9 7 j 0 0 5 2 9 - 2
M. Hidaka et al.
128
Physica B 241 243 (1998) 127 129
of the thermoluminescence consists of a clear single peak (neither doublet nor triplet peaks), giving rise to a very good linearity of the brightness of the thermoluminescence on the stored energy induced by the external ionising radiation. Fig. la shows a dynamic range of the (BaSO4: Er, C1) phosphor against neutrons. The good linearity suggests that a dynamic range of the present phosphors has a magnitude of about 8. Another important
The thickness of the TLS was about 200-400 ~tm, and was flexible. Thus, it can be easily set up in a cylindrical film-cassette for the neutron diffraction camera. The optical detector system measuring the stored energy in TLS was mainly composed of a thermoluminescence reader (TL-reader) and a data analyzer. The poly-crystalline phosphors (BaSO4: Er, Cl) emit the thermoluminescence of about 390 nm, on heating to 250"C. A grow curve
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M. Hidaka et al. / Physica B 241 243 (1998) I27 129
129
19
Fig. 2. Example of a visual image of the oscillatory diffraction pattern from ferroelectric K 2 S e O 4.
function for the neutron detector is a fading effect of the stored energy in the TLS sheet. Fig. lb shows the fading effect of the present sheet at various thermal conditions. The present TLS can keep the stored energy for over 100 days even if the sheet is maintained at room temperature. In order to demonstrate an application of the present neutron detector, we carried out measurements of an oscillatory patterns of the neutron diffractions by using a provisional neutron Weissenberg camera. The sheet had a size of about 100 x 300 mm 2, and covered scattering angle of about 160 c. Fig. 2 shows a typical example of a visual image of the oscillatory diffraction pattern taken from a single crystal of ferroelectric compound KzSeO4 with 5 x 8 × 8 m m 3 at room temperature. The used neutron wavelength was 0.2445 nm, and the exposure time was 5.5 h. The scanning angle of the crystal was 20 ~' around a rotational axis of the Weissenberg camera. In the figure, one can clearly see the usefulness of the TLS detector for
a simultaneous measurement of the numbers of reflections.
3. Conclusion In conclusion, we developed a new thermolumino neutron detector. The TLS sheet can be utilized for recording of two-dimensional visual images of a number of reflections such as diffuse scattering, incommensurate superlattice reflections, or satellite-like reflections. Furthermore, the TLS sheet is flexible and it can be repeatedly used. Further improvements of the TLS sheet-detector and the reading system are now in progress.
Reference [1] Activity report of Neutron scattering laboratory, I.S.S.P., Univ. of Tokyo, vol. 3, 1996.
Physica B 241 243 (1998) 127 129
A new t h e r m o - l u m i n o neutron detector M. Hidaka a'*, H. Akiyama b, H. Fujii c, H. Yoshizawa d, Y. Kawamura d, Y.
Fujii d
Department of Physics, Kyushu UniversiO,. Fukuoka 812-8l, Japan b Faculty ~fEducation, M~vazaki UniversiO,, Mo,azaki 889-21, Japan c Facul~ of Education. Oita University, Oita 870-11. Japan d Neutron Scattering LaboratotT. I.S.S.P.. Univ. of Tolg,o. Tokai, lbaraki 319- l 1, Japan
Abstract A new neutron diffraction detector has been developed, which utilizes the effect of thermoluminescence. The system is composed of a thermo-lumino sheet which functions as a neutron converter and a CCD camera. The thermo-lumino sheet is made by a complex of (I°B-BaSO4: Er, C1), while the CCD camera records the thermoluminescence from the sheet, yielding a two-dimensional visual image of neutron scattering. The thermo-lumino sheet is quite stable to various atmospheric conditions (temperature, humidity, illumination, and external strain), and can be repeatedly used after annealing. ~" 1998 Published by Elsevier Science B.V. All rights reserved. Kevwords: Detectors; Imaging; Thermoluminescence
1. Introduction A neutron diffraction camera is a convenient tool and has some advantages over an ordinary counter system in order to observe the diffraction patterns in the two-dimensional reciprocal space. For a camera method, a sheet of 6LiF + ZnP(Ag) which sandwich an X-ray film has been used as a neutron scintillator. The X-ray film was, however, not efficient to obtain quantitative data of the reflections because of its poor dynamic range of neutron intensity. We have been attempting to develop an alternative film-type detector which is simple to handle and whose production cost is inexpensive. In the
* Corresponding author.
present paper, we will report the newly developed detector system for neutron diffraction.
2. Experimental In order to obtain the visual image of neutron diffraction, we employed thermal luminosity of defective poly-crystalline compound to the present neutron detector [1]. As a material for a neutron converter, we empirically chose a phospher complex doped with a few rare-earth ions; (l°B BaSO4: Er, C1). The a particles emitted from 1°B through a (n, a) reaction activate the thermal luminosity of the phospher complex. The phospher complex was lapped by Teflon sheets into a binder shape. We called it a thermo-lumino sheet (TLS).
0921-4526/98/$19.00 ~' 1998 Published by Elsevier Science B.V. All rights reserved PII S092 1- 4 5 2 6 ( 9 7 j 0 0 5 2 9 - 2
M. Hidaka et al.
128
Physica B 241 243 (1998) 127 129
of the thermoluminescence consists of a clear single peak (neither doublet nor triplet peaks), giving rise to a very good linearity of the brightness of the thermoluminescence on the stored energy induced by the external ionising radiation. Fig. la shows a dynamic range of the (BaSO4: Er, C1) phosphor against neutrons. The good linearity suggests that a dynamic range of the present phosphors has a magnitude of about 8. Another important
The thickness of the TLS was about 200-400 ~tm, and was flexible. Thus, it can be easily set up in a cylindrical film-cassette for the neutron diffraction camera. The optical detector system measuring the stored energy in TLS was mainly composed of a thermoluminescence reader (TL-reader) and a data analyzer. The poly-crystalline phosphors (BaSO4: Er, Cl) emit the thermoluminescence of about 390 nm, on heating to 250"C. A grow curve
10 6
E E
10 5
'C:: Z~
-,2
10 4
v
£3 J LU
10 3
>-
J I.--
10 2
101
10 o 10 `2
10 -1
10 0
10 ~
10 2
10 3
10 4
10 5
RADIATION DOSE (dpm/mm 2)
(a)
1.0
4~ o
E-
•
£3 .~ 0.5 LU >._1 I..-
•
0.0
.
10 -2
(b)
.
.
.
' ' " l
10 -1
'
'
' ' ' ' " 1
'
10 0
' ' ' ' " 1
'
'
101
' ' ' ' ' ' 1
'
10 2
'
•
1 3 5 (5,
. •
52°C 20%
v
20~C
' ' ' ' " f
10 3
S T O R A G E T I M E (days)
Fig. 1. [a) D y n a m i c range of a t h e r m o - l u m i n o sheel. (b) Time d e p e n d e n c c of the efficiency of a t h e r m o - l u m i n o sheet.
M. Hidaka et al. / Physica B 241 243 (1998) I27 129
129
19
Fig. 2. Example of a visual image of the oscillatory diffraction pattern from ferroelectric K 2 S e O 4.
function for the neutron detector is a fading effect of the stored energy in the TLS sheet. Fig. lb shows the fading effect of the present sheet at various thermal conditions. The present TLS can keep the stored energy for over 100 days even if the sheet is maintained at room temperature. In order to demonstrate an application of the present neutron detector, we carried out measurements of an oscillatory patterns of the neutron diffractions by using a provisional neutron Weissenberg camera. The sheet had a size of about 100 x 300 mm 2, and covered scattering angle of about 160 c. Fig. 2 shows a typical example of a visual image of the oscillatory diffraction pattern taken from a single crystal of ferroelectric compound KzSeO4 with 5 x 8 × 8 m m 3 at room temperature. The used neutron wavelength was 0.2445 nm, and the exposure time was 5.5 h. The scanning angle of the crystal was 20 ~' around a rotational axis of the Weissenberg camera. In the figure, one can clearly see the usefulness of the TLS detector for
a simultaneous measurement of the numbers of reflections.
3. Conclusion In conclusion, we developed a new thermolumino neutron detector. The TLS sheet can be utilized for recording of two-dimensional visual images of a number of reflections such as diffuse scattering, incommensurate superlattice reflections, or satellite-like reflections. Furthermore, the TLS sheet is flexible and it can be repeatedly used. Further improvements of the TLS sheet-detector and the reading system are now in progress.
Reference [1] Activity report of Neutron scattering laboratory, I.S.S.P., Univ. of Tokyo, vol. 3, 1996.