- Email: [email protected]
Comparison between muon and positron images using imaging plates
ARTICLE IN PRESS Nuclear Instruments and Methods in Physics Research A 600 (2009) 60–63
Contents lists available at ScienceDirect
Nuclear Instruments and Methods in Physics Research A journal homepage: www.elsevier.com/locate/nima
Comparison between muon and positron images using imaging plates Masao Doyama a,, Yoshiaki Kogure a, Miyoshi Inoue a, Toshikazu Kurihara b, Xingzhong Cao b, Kusuo Nishiyama c, Koichiro Shimomura c a b c
Teikyo University of Science and Technology, Uenohara, Yamanashi 409-0193, Japan Slow Positron Facility, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan Muon Science Laboratory, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan
a r t i c l e in f o
a b s t r a c t
Available online 27 November 2008
A muon beam intensity distribution perpendicular to the beam has been obtained using imaging plates that are commonly used in X-ray science, medical analysis, and transmission electron microscopy. The resolution of the imaging plates depends on the resolution of the imaging plate reader. We have used BAS-TR2025 imaging plates and a Bio-Imaging Analyzer (BAS-2500 or BAS-3000). The positional resolution is 50 mm 50 mm. When the beam is one kind, because a coincidence measurement is not necessary, the muon distribution perpendicular to the beam is taken in a very short time, and the spatial resolution is 50 mm 50 mm. Such a resolution cannot be obtained by the usual muon measuring method. This is quite convenient to adjust muon beams. When FLA-8000 or FLA-9000 is used, the resolution can be improved to 10 mm 10 mm. Such an intensity resolution of muon beams could not be imagined without using imaging plates. Obtained transmission muon images are also presented. This can be used as a non-destructive test. & 2008 Published by Elsevier B.V.
Keywords: Muons Solid-state detectors Muon transmission images Imaging plates
1. Introduction Imaging plates are widely used in X-ray science, medical analysis, and transmission electron microscopy. A plate is only a card that can be easily placed into a vacuum chamber without requiring darkness. Darkness is required only during exposure and when transferring imaging plates to an analyzer (reader). The images can be erased, and imaging plates can be used many times. Because the imaging intensity is cumulative, it is not good for coincidence measurements. However, when the kinds of particles arriving are known, and particularly particles are of one kind, not mixed, imaging plates are quite conveniently and usefully used. The sensitivity is quite high and proportional to the fluence to six digits. The dead times in coincidence or anticoincidence circuits are not a problem in imaging plates. Imaging plates can be cut to the sizes we want. We have found that imaging plates are quite sensitive to positrons [1]. In this paper we show that imaging plates are also sensitive to muons. During the last run of Muon Science Laboratory, KEK, Tsukuba, we applied imaging plates for muons. This was probably the first application of imaging plates to muons. Because the penetration depth was large, we used Type FDL UR-V Imaging Plates (Fuji Photo Film Co., Ltd.), which are widely used in transmission electron microscopy. The size of a plate was 81 100 mm2. The surface was covered Corresponding author. Tel.: +81 554 63 4411; fax: +81 554 63 4431.
E-mail address: [email protected] (M. Doyama). 0168-9002/$ - see front matter & 2008 Published by Elsevier B.V. doi:10.1016/j.nima.2008.11.064
by a protective layer. Below the protective layer, there was a particle-sensitive layer, which is composed of Eu+2-doped barium fluorohalides phosphors. After exposure, the IP-recorded layer was scanned by a He–Ne Laser (633 nm). The photo-stimulated luminescence (PSL) per area, I, was proportional to PSL (I is expressed in the unit of PSL/mm2). The transmission muon images were compared with transmission positron images. The similarities and the differences are shown. Generally speaking, transmission muon images have a higher contrast compared with the corresponding transmission positron images. By using muons with high energies, transmission muon images can be obtained. This could be used as a nondestructive testing method, which could open a new field in muon science.
2. Intensity distribution of muon and positron beams An imaging plate was inserted in a black paper envelope (100-
mm-thick), through which light could not penetrate. The envelope was placed perpendicular to the muon beam. We used surfacepositive muons. The momentum was about 26 MeV/c. The particles coming through the channel are almost all positive muons. When we intended to obtain a transmission image of samples by muons, a sample was set just in front of the imaging plate (in a black envelope). Transmission images by muons were obtained similar to the X-ray transmission images.
ARTICLE IN PRESS M. Doyama et al. / Nuclear Instruments and Methods in Physics Research A 600 (2009) 60–63
61
Fig. 1. Muon beam intensity distribution perpendicular to the beam. The 50 mm 50 mm/pixel was used. The voltages applied to the deflector were 90 kV (a), 100 kV (b), and 110 kV (c).
After the imaging plate was exposed to a muon beam for 10 min, it was transferred to a Reader (BAS-2500) that was located at the Photon Factory, KEK. A gradient of 65,536, a sensitivity of 4000, and a resolution of 50 mm 50 mm/pixel were used. The result is shown in Fig. 1. We had never seen the muon beam intensity distribution to the resolution of 50 mm 50 mm. This method can be applied to adjust muon beams. The beam was almost round. We saw that the peak of the muon beam intensity was shifted as the deflector voltage was changed. Fig. 2(a)–(c) shows the corresponding muon intensities as shown in Fig. 1(a)–(c). The shapes change as the deflector voltage becomes higher. The higher the voltage, the more asymmetric the shape. Fig. 3(a) shows an example of a positron beam of time of flight (TOF) at the Slow Positron Facility, KEK. Fig. 3(b) shows the positron intensity across the centre.
3. Transmission muon bio-images
0
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Fig. 4(a) shows a transmission muon image of a wing of a cicada. The muon beam was restricted to the darker area. Fig. 5(a) shows transmission muon images of small shrimps. Figs. 4(b) and 5(b) show the same specimen images by positrons. Transmission positron images have a lower contrast, but muon images have a higher contrast compared with positron images, in general. Details of the imaging particles on imaging plates are not clear at present.
4. Most interesting transmission muon images Fig. 6 shows a transmission muon image of copper (a) and tungsten (b) foils (40 mm thick each). At the cross part, the thickness is 80 mm. The dark circle is the muon beam. The place where muons did not arrive outside the circle is white. The exposure time was 30 min. In Fig. 6(a), the place where muons passed a foil of 40 mm is darker than the background of the circle. However, fewer muons should have arrived. The places where muons passed two copper foils (80 mm thick) are the darkest. Fig. 6(b) shows a transmission muon image of tungsten foils (40 mm thick). At the cross part, the thickness is 80 mm. The place where muons passed a 40-mm-thick tungsten foil is darker than the background of the circle. The place where muons passed two tungsten foils (80 mm thick) is the lightest within the circle. There are two reasons to be considered. One is due to the Bragg peak and the other is the energy of muons arriving at the particlesensitive layer. Muons with high energies pass the sensitive layer, but muons with lower energies are trapped in the sensitive layers. In the case of positrons, the relation between PSL and the positron energies has been studied [2]. The relation between positive muon momentum and range is shown in Fig. 7. Muons that passed through a black envelope lost their energies. A tentative explanation of Fig. 6 is as follows. Near the centre, the doubled zone is the darkest in Fig. 6(a). It looks as though more positive
Fig. 2. (a–c) are corresponding intensities of muons PSL/mm2 (horizontal axis) shown in the region within the two vertical parallel lines in Fig. 1(a)–(c). The vertical axis shows the corresponding position (arbitrary scale) shown in Fig. 1. The unit is about 0.3 mm on IP.
muons reached the imaging plate, but this is probably due to the peak of the Bragg curve of the muons. In that case, it indicates that the muon range is only slightly more than enough to penetrate the two sheets of copper layers. The muon momentum corresponding to 80 mm range in copper is 22 MeV/c according to Fig. 7, so let us assume the muon momentum arriving at the surface of copper foil is about 23 MeV/c. At the place where no samples exist, the muon energies are high and some muons may have penetrated the particle-sensitive layer of the imaging plate. After muons passed one sheet of copper or tungsten foil, the kinetic energies of muons were lowered and they were absorbed. Slower muons were trapped in the particle-sensitive layer of the imaging plate. In Fig. 6(b), the double-layer part of the tungsten foil is whiter than the background. If the same positive muons with about 23 MeV/c momentum arrive at the surface of the tungsten foil, the
ARTICLE IN PRESS 62
M. Doyama et al. / Nuclear Instruments and Methods in Physics Research A 600 (2009) 60–63
5 cm I-----------------------------------I Fig. 4. (a). Transmission muon image of a wing of a cicada; 50 mm 50 mm/pixel was used. (b) Transmission positron image of the same wing of the cicada.
RANGE [/MICRO METER]
Fig. 3. (a) Positron beam (15 kV) intensity distribution perpendicular to the beam; 50 mm 50 mm/pixel was used. (b) Positron beam (15 kV) intensity distribution perpendicular to the beam. PSL is plotted along the diagonal line in (a).
POSITIVE MUON RANGE
300 250 200 150 100 50 0
20
25 POSITIVE MUON MOMENTUM [/(MeV/c)]
30
Fig. 7. Relation between the momenta of positive muons and ranges. The upper curve is for copper and the lower curve is for tungsten.
I---------------------------I 5 cm
I---------------I 5 cm
Fig. 5. (a) Transmission muon image of small shrimps. The contrast of the image is high. (b) Transmission positron image. The contrast of the image is lower than that of the muons.
5 cm I-----------------------I Fig. 8. (a) Digital camera image of a plug. (b) Transmission muon image of the plug shown in (a); 50 mm 50 mm/pixel was used.
muon range is about 65 mm, which is less than the thickness of two tungsten sheets, i.e. 80 mm. Therefore, muons do not reach the imaging plate.
5. Transmission muon images
I-------------------------------------I 5 cm Fig. 6. Transmission muon image of copper (a) and tungsten (b) foils (each thickness is 40 mm); 50 mm 50 mm/pixel was used. The double layer in (a) is the darkest, but the double layer of (b) is the lightest.
Positive muons of about 100 MeV were used. Fig. 8(a) shows a picture of a brass plug coated with nickel, taken by a digital camera. Fig. 8(b) shows a transmission muon image of the plug. The muon beam even penetrated the plug. The circle is the muon beam. A hole at the centre can be seen.
ARTICLE IN PRESS M. Doyama et al. / Nuclear Instruments and Methods in Physics Research A 600 (2009) 60–63
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50 mm. Wide applications can be expected in the future. For detailed explanations, more experiments are required.
Acknowledgement
Fig. 9. Transmission muon image of a boiled egg.
Fig. 9 is a transmission image of a boiled egg. Even the air space can be seen.
6. Summary Imaging plates can be used to observe the details of muon beams and the inside of materials to a positional resolution of
The present experiments were performed between December 2005 and March 2006 as a Collaborative Experiment Muon Science Laboratory, KEK, under registration number A02. We express our gratitude for providing us a great chance to perform the experiments just before closing the Muon Science Laboratory in Tsukuba. References [1] Masao Doyama, J. Takano, M. Inoue, T. Yoshiie, Y. Hayashi, M. Kiritani, T. Oikawa, Nuclear Instruments and Methods in Physics Research A 394 (1997) 146. [2] M. Doyama, Y. Kogre, M. Inoue, T. Kurihara, T. Yoshiie, R. Oshima, M. Matsuya, Applied Surface Science 252 (2006) 3126.
Contents lists available at ScienceDirect
Nuclear Instruments and Methods in Physics Research A journal homepage: www.elsevier.com/locate/nima
Comparison between muon and positron images using imaging plates Masao Doyama a,, Yoshiaki Kogure a, Miyoshi Inoue a, Toshikazu Kurihara b, Xingzhong Cao b, Kusuo Nishiyama c, Koichiro Shimomura c a b c
Teikyo University of Science and Technology, Uenohara, Yamanashi 409-0193, Japan Slow Positron Facility, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan Muon Science Laboratory, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan
a r t i c l e in f o
a b s t r a c t
Available online 27 November 2008
A muon beam intensity distribution perpendicular to the beam has been obtained using imaging plates that are commonly used in X-ray science, medical analysis, and transmission electron microscopy. The resolution of the imaging plates depends on the resolution of the imaging plate reader. We have used BAS-TR2025 imaging plates and a Bio-Imaging Analyzer (BAS-2500 or BAS-3000). The positional resolution is 50 mm 50 mm. When the beam is one kind, because a coincidence measurement is not necessary, the muon distribution perpendicular to the beam is taken in a very short time, and the spatial resolution is 50 mm 50 mm. Such a resolution cannot be obtained by the usual muon measuring method. This is quite convenient to adjust muon beams. When FLA-8000 or FLA-9000 is used, the resolution can be improved to 10 mm 10 mm. Such an intensity resolution of muon beams could not be imagined without using imaging plates. Obtained transmission muon images are also presented. This can be used as a non-destructive test. & 2008 Published by Elsevier B.V.
Keywords: Muons Solid-state detectors Muon transmission images Imaging plates
1. Introduction Imaging plates are widely used in X-ray science, medical analysis, and transmission electron microscopy. A plate is only a card that can be easily placed into a vacuum chamber without requiring darkness. Darkness is required only during exposure and when transferring imaging plates to an analyzer (reader). The images can be erased, and imaging plates can be used many times. Because the imaging intensity is cumulative, it is not good for coincidence measurements. However, when the kinds of particles arriving are known, and particularly particles are of one kind, not mixed, imaging plates are quite conveniently and usefully used. The sensitivity is quite high and proportional to the fluence to six digits. The dead times in coincidence or anticoincidence circuits are not a problem in imaging plates. Imaging plates can be cut to the sizes we want. We have found that imaging plates are quite sensitive to positrons [1]. In this paper we show that imaging plates are also sensitive to muons. During the last run of Muon Science Laboratory, KEK, Tsukuba, we applied imaging plates for muons. This was probably the first application of imaging plates to muons. Because the penetration depth was large, we used Type FDL UR-V Imaging Plates (Fuji Photo Film Co., Ltd.), which are widely used in transmission electron microscopy. The size of a plate was 81 100 mm2. The surface was covered Corresponding author. Tel.: +81 554 63 4411; fax: +81 554 63 4431.
E-mail address: [email protected] (M. Doyama). 0168-9002/$ - see front matter & 2008 Published by Elsevier B.V. doi:10.1016/j.nima.2008.11.064
by a protective layer. Below the protective layer, there was a particle-sensitive layer, which is composed of Eu+2-doped barium fluorohalides phosphors. After exposure, the IP-recorded layer was scanned by a He–Ne Laser (633 nm). The photo-stimulated luminescence (PSL) per area, I, was proportional to PSL (I is expressed in the unit of PSL/mm2). The transmission muon images were compared with transmission positron images. The similarities and the differences are shown. Generally speaking, transmission muon images have a higher contrast compared with the corresponding transmission positron images. By using muons with high energies, transmission muon images can be obtained. This could be used as a nondestructive testing method, which could open a new field in muon science.
2. Intensity distribution of muon and positron beams An imaging plate was inserted in a black paper envelope (100-
mm-thick), through which light could not penetrate. The envelope was placed perpendicular to the muon beam. We used surfacepositive muons. The momentum was about 26 MeV/c. The particles coming through the channel are almost all positive muons. When we intended to obtain a transmission image of samples by muons, a sample was set just in front of the imaging plate (in a black envelope). Transmission images by muons were obtained similar to the X-ray transmission images.
ARTICLE IN PRESS M. Doyama et al. / Nuclear Instruments and Methods in Physics Research A 600 (2009) 60–63
61
Fig. 1. Muon beam intensity distribution perpendicular to the beam. The 50 mm 50 mm/pixel was used. The voltages applied to the deflector were 90 kV (a), 100 kV (b), and 110 kV (c).
After the imaging plate was exposed to a muon beam for 10 min, it was transferred to a Reader (BAS-2500) that was located at the Photon Factory, KEK. A gradient of 65,536, a sensitivity of 4000, and a resolution of 50 mm 50 mm/pixel were used. The result is shown in Fig. 1. We had never seen the muon beam intensity distribution to the resolution of 50 mm 50 mm. This method can be applied to adjust muon beams. The beam was almost round. We saw that the peak of the muon beam intensity was shifted as the deflector voltage was changed. Fig. 2(a)–(c) shows the corresponding muon intensities as shown in Fig. 1(a)–(c). The shapes change as the deflector voltage becomes higher. The higher the voltage, the more asymmetric the shape. Fig. 3(a) shows an example of a positron beam of time of flight (TOF) at the Slow Positron Facility, KEK. Fig. 3(b) shows the positron intensity across the centre.
3. Transmission muon bio-images
0
100
200
0
50
100
150
200
250
0
50
100
150
200
250
Fig. 4(a) shows a transmission muon image of a wing of a cicada. The muon beam was restricted to the darker area. Fig. 5(a) shows transmission muon images of small shrimps. Figs. 4(b) and 5(b) show the same specimen images by positrons. Transmission positron images have a lower contrast, but muon images have a higher contrast compared with positron images, in general. Details of the imaging particles on imaging plates are not clear at present.
4. Most interesting transmission muon images Fig. 6 shows a transmission muon image of copper (a) and tungsten (b) foils (40 mm thick each). At the cross part, the thickness is 80 mm. The dark circle is the muon beam. The place where muons did not arrive outside the circle is white. The exposure time was 30 min. In Fig. 6(a), the place where muons passed a foil of 40 mm is darker than the background of the circle. However, fewer muons should have arrived. The places where muons passed two copper foils (80 mm thick) are the darkest. Fig. 6(b) shows a transmission muon image of tungsten foils (40 mm thick). At the cross part, the thickness is 80 mm. The place where muons passed a 40-mm-thick tungsten foil is darker than the background of the circle. The place where muons passed two tungsten foils (80 mm thick) is the lightest within the circle. There are two reasons to be considered. One is due to the Bragg peak and the other is the energy of muons arriving at the particlesensitive layer. Muons with high energies pass the sensitive layer, but muons with lower energies are trapped in the sensitive layers. In the case of positrons, the relation between PSL and the positron energies has been studied [2]. The relation between positive muon momentum and range is shown in Fig. 7. Muons that passed through a black envelope lost their energies. A tentative explanation of Fig. 6 is as follows. Near the centre, the doubled zone is the darkest in Fig. 6(a). It looks as though more positive
Fig. 2. (a–c) are corresponding intensities of muons PSL/mm2 (horizontal axis) shown in the region within the two vertical parallel lines in Fig. 1(a)–(c). The vertical axis shows the corresponding position (arbitrary scale) shown in Fig. 1. The unit is about 0.3 mm on IP.
muons reached the imaging plate, but this is probably due to the peak of the Bragg curve of the muons. In that case, it indicates that the muon range is only slightly more than enough to penetrate the two sheets of copper layers. The muon momentum corresponding to 80 mm range in copper is 22 MeV/c according to Fig. 7, so let us assume the muon momentum arriving at the surface of copper foil is about 23 MeV/c. At the place where no samples exist, the muon energies are high and some muons may have penetrated the particle-sensitive layer of the imaging plate. After muons passed one sheet of copper or tungsten foil, the kinetic energies of muons were lowered and they were absorbed. Slower muons were trapped in the particle-sensitive layer of the imaging plate. In Fig. 6(b), the double-layer part of the tungsten foil is whiter than the background. If the same positive muons with about 23 MeV/c momentum arrive at the surface of the tungsten foil, the
ARTICLE IN PRESS 62
M. Doyama et al. / Nuclear Instruments and Methods in Physics Research A 600 (2009) 60–63
5 cm I-----------------------------------I Fig. 4. (a). Transmission muon image of a wing of a cicada; 50 mm 50 mm/pixel was used. (b) Transmission positron image of the same wing of the cicada.
RANGE [/MICRO METER]
Fig. 3. (a) Positron beam (15 kV) intensity distribution perpendicular to the beam; 50 mm 50 mm/pixel was used. (b) Positron beam (15 kV) intensity distribution perpendicular to the beam. PSL is plotted along the diagonal line in (a).
POSITIVE MUON RANGE
300 250 200 150 100 50 0
20
25 POSITIVE MUON MOMENTUM [/(MeV/c)]
30
Fig. 7. Relation between the momenta of positive muons and ranges. The upper curve is for copper and the lower curve is for tungsten.
I---------------------------I 5 cm
I---------------I 5 cm
Fig. 5. (a) Transmission muon image of small shrimps. The contrast of the image is high. (b) Transmission positron image. The contrast of the image is lower than that of the muons.
5 cm I-----------------------I Fig. 8. (a) Digital camera image of a plug. (b) Transmission muon image of the plug shown in (a); 50 mm 50 mm/pixel was used.
muon range is about 65 mm, which is less than the thickness of two tungsten sheets, i.e. 80 mm. Therefore, muons do not reach the imaging plate.
5. Transmission muon images
I-------------------------------------I 5 cm Fig. 6. Transmission muon image of copper (a) and tungsten (b) foils (each thickness is 40 mm); 50 mm 50 mm/pixel was used. The double layer in (a) is the darkest, but the double layer of (b) is the lightest.
Positive muons of about 100 MeV were used. Fig. 8(a) shows a picture of a brass plug coated with nickel, taken by a digital camera. Fig. 8(b) shows a transmission muon image of the plug. The muon beam even penetrated the plug. The circle is the muon beam. A hole at the centre can be seen.
ARTICLE IN PRESS M. Doyama et al. / Nuclear Instruments and Methods in Physics Research A 600 (2009) 60–63
63
50 mm. Wide applications can be expected in the future. For detailed explanations, more experiments are required.
Acknowledgement
Fig. 9. Transmission muon image of a boiled egg.
Fig. 9 is a transmission image of a boiled egg. Even the air space can be seen.
6. Summary Imaging plates can be used to observe the details of muon beams and the inside of materials to a positional resolution of
The present experiments were performed between December 2005 and March 2006 as a Collaborative Experiment Muon Science Laboratory, KEK, under registration number A02. We express our gratitude for providing us a great chance to perform the experiments just before closing the Muon Science Laboratory in Tsukuba. References [1] Masao Doyama, J. Takano, M. Inoue, T. Yoshiie, Y. Hayashi, M. Kiritani, T. Oikawa, Nuclear Instruments and Methods in Physics Research A 394 (1997) 146. [2] M. Doyama, Y. Kogre, M. Inoue, T. Kurihara, T. Yoshiie, R. Oshima, M. Matsuya, Applied Surface Science 252 (2006) 3126.