- Email: [email protected]
Evaluation of piezoelectric lead–zirconate–titanate multilayered detector by Fourier analysis
ARTICLE IN PRESS
Nuclear Instruments and Methods in Physics Research A 577 (2007) 741–744 www.elsevier.com/locate/nima
Evaluation of piezoelectric lead–zirconate–titanate multilayered detector by Fourier analysis Seiji Takechia,, Toshiyuki Onishia, Shigeyuki Minamia, Takashi Miyachib, Masayuki Fujiib, Nobuyuki Hasebeb, Kunishiro Morib, Hiromi Shibatac, Takeshi Murakamid, Yukio Uchihorid, Nagaya Okadae a Graduate School of Engineering, Osaka City University, Osaka 558-8585, Japan Advanced Research Institute for Science and Engineering, Waseda University, Tokyo 169-8555, Japan c Graduate School of Engineering, Kyoto University, Kyoto 606-8501, Japan d National Institute of Radiological Sciences, Chiba 263-8555, Japan e Honda Electronics Co. Ltd., Toyohashi, Aichi 441-3193, Japan
b
Received 22 March 2007; received in revised form 10 April 2007; accepted 13 April 2007 Available online 20 April 2007
Abstract Radiation detectors composed of lead–zirconate–titanate (PZT) were studied by directly irradiating them with a 400 MeV/n xenon beam. Fourier analysis revealed that frequency components of the output signal obtained from the detectors explicitly depended on the beam pulse duration. The sensitivity of the multilayered detector was discussed in comparison with that of a single-layered detector. r 2007 Elsevier B.V. All rights reserved. PACS: 29.40.n; 43.38.+n; 43.58.+z; 77.65.Ly Keywords: Lead–zirconate–titanate (PZT); Piezoelectric effect; Multilayers; Acoustic radiation detector
1. Introduction Up to now, radiation detectors have been operated on the basis of the principles of ionization and/or excitation in absorbing media. Besides these principles, phonon-associated processes have also been taken into account [1]. However, there are very few reports on detectors operated on the basis of elasticity at room temperature. We have been interested in radiation detectors based on the acoustic principle [2–6]. This report concerns the characteristics of a detector in which piezoelectric lead–zirconate–titanate (PZT) is used as the absorber as well as the sensor itself. In a previous study [6], we treated the general features of the multilayered structure in order to realize a highly sensitive detector. In this study, the characteristics of a multilayered detector were investigated through Fourier analysis of the Corresponding author. Tel.: +81 6 6605 2677; fax: +81 6 6690 2745.
E-mail address: [email protected] (S. Takechi). 0168-9002/$ - see front matter r 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.nima.2007.04.137
output signal waveform. It was found that the power spectrum contained a higher frequency component as the beam pulse duration became shorter. As discussed in ref. [1], the sensitivity of the multilayered detector was better than that of a single-layered detector. Consequently, the results of Fourier analysis provide insight into the production mechanism of output voltage. Since there are very few reports on such a production mechanism, the presented data were considered to be worth reporting to improve the detector that is based on the acoustic principle at room temperature.
2. Experimental method 2.1. Detectors Since we are interested in piezoelectricity, two types of detectors were used: single-layered and multilayered detectors. The detector thickness was determined to be
ARTICLE IN PRESS S. Takechi et al. / Nuclear Instruments and Methods in Physics Research A 577 (2007) 741–744
742
8 mm in order to confine 400 MeV/n xenon ions, the range of which is 7.8 mm in PZT. The single-layered detector was fabricated with homogeneously baked PZT that was 20 mm in diameter. Hereafter, this detector is referred to as the single-layered detector (SD). The multilayered detector was fabricated by stacking 80-mm-thick PZT disks of 20 mm diameter. A 2-mm-thick metal sheet that was made of Ag–Pd was sandwiched between disks. One hundred disks were joined by baking. Hereafter, this detector is referred to as the multilayered detector (MD). Silver electrodes with a thickness of a few mm were coated onto both flat surfaces. Both detectors were polarized in the direction normal to the flat surface. The electrostatic capacitance of SD was 770 pF and that of MD was 650 pF.
chopper. The beam intensity was monitored by the counter. A frame made of epoxy resin supported the detector. The frame was suspended by four springs to prevent noise arising from mechanical disturbances. Moreover, in order to eliminate noise originating from the variation in atmospheric pressure, the detector was set in a closed chamber in which the internal pressure was maintained below 1 Torr. The chamber, which was made from transparent acrylic resin to enable visual confirmation of the alignment, was placed 18 cm downstream of the scintillation counter. The signal obtained from the detector was processed with an amplifier, and then transferred to a digital oscilloscope. The processed signal was averaged over 100 events in the oscilloscope to suppress the effects of random noise. Digitally processed data were stored in a personal computer.
2.2. Experimental setup 3. Results and discussion The experimental arrangement is schematically shown in Fig. 1. A 400 MeV/n Xe beam was supplied by the Heavy Ion Medical Accelerator in Chiba (HIMAC) at the National Institute of Radiological Sciences [7]. The beam was originally extracted for 0.3 s within a period of 3.3 s. We adopted a chopper to obtain a short pulsed beam. The chopper was a rotating stainless-steel disk with a diameter of 30 cm and a thickness of 10 mm, in which four slits with a length of 10 mm and a width of 1 mm were perforated in an equiangular manner. The disk was installed 73 cm downstream of the exit of the beam duct. By adjusting the rotation speed, the beam intensity could be varied in accordance with the change in the pulse duration from 50 to 200 ms [5]. When the rotation speed was 30 rps, the beam duration became 120 ms and the typical number of xenon ions was 200 per slit window. A 1-mm-thick plastic scintillation counter was placed 34 cm downstream of the
SCALER PC Disc. Oscilloscope PMT
Amplifier
PZT Beam Chamber Chopper
Scintillator
Slit
Disk Fig. 1. Schematic view of experimental configuration. Here, photomultiplier is indicated as PMT, discriminator as Disc., and personal computer as PC.
We have investigated the response of the two types of PZT detectors to a 400 MeV/n Xe beam, changing the beam pulse duration by adjusting the rotation speed of the chopper disk. Fig. 2(a) shows the output signal obtained from the photomultiplier when the chopper disk rotated at 45 rps. The signal appeared at the time when the beam passed through the slit. The pulse duration was recognized to be 100 ms. The waveforms of output voltage observed from SD and MD are shown in Figs. 2(b) and (c), respectively. Here, the output amplitude is defined as Vp indicated in the figures. It can be seen that Vp obtained from MD was larger than that from SD. It is found that MD is more sensitive to the high-energy xenon ion beam than SD under these experimental conditions. Next, signal waveforms observed from both SD and MD were analyzed by Fourier transformation. The frequency distribution from 1 kHz to 500 MHz was examined. Fig. 3(a) shows the power spectrum distribution up to 100 kHz, obtained from data in Figs. 2(b) and (c). Note that no significant spectrum appeared at any frequency beyond 100 kHz. It can be seen from Fig. 3(a) that a peak appeared at 89 kHz when SD was used. Similar peaks were observed only from SD at any rotation speed within this experimental condition. A PZT disk 20 mm in diameter has a fundamental resonant frequency of 90 kHz toward the radial direction, which corresponds to the transverse waves propagating in the PZT. The time when the peak frequency appears was examined through continuous wavelet transformation. However, localization on the time axis for frequency was not recognized in the transformed plot. Therefore, the frequency component is considered to be that from noise. One of the reasons why the waveform observed from MD did not contain the above frequency component may be due to difference in the impedance between SD and MD. Fig. 3(b) shows the power spectra obtained from MD at various rotation speeds. Here, each power spectrum was normalized to each maximum value obtained at 1 kHz. It is found that the signal contained
ARTICLE IN PRESS S. Takechi et al. / Nuclear Instruments and Methods in Physics Research A 577 (2007) 741–744
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Fig. 3. Power spectra from 1 to 100 kHz obtained by Fourier transformation (a) of data from Figs. 2(b) and (c) and Fig. 3(b) of data from MD when chopper disk rotated at 15, 30, and 45 rps.
Fig. 2. Typical waveforms of output signal observed from (a) photomultiplier, (b) SD, and (c) MD when chopper disk rotated at 45 rps.
higher frequency components as the rotation speed increased. This indicates that the variation of the beam pulse frequency was directly reflected in the output voltage observed from the detectors. It is also found that the spectra within 20 kHz obtained from MD are larger than those from SD under these experimental conditions. Note that the beam pulse frequency lay within 20 kHz. Fig. 4 shows the curves reconstructed by inverse Fourier transformation from the frequency components below 20 kHz in Fig. 3(a). These waveforms hold almost the same shape as shown in Figs. 2(b) and (c). This implies that the resonant frequency components did not contribute to the output voltage observed from the PZT detector. Here,
Fig. 4. Output waveforms reconstructed by inverse Fourier transformation when chopper disk rotated at 45 rps. Only frequency components below 20 kHz were used.
ARTICLE IN PRESS 744
S. Takechi et al. / Nuclear Instruments and Methods in Physics Research A 577 (2007) 741–744
components inherent to the PZT detector but of those dependent on the beam pulse duration. It was also found that the sensitivity was independent of the rotation speed. These results are useful for the application of PZT not only in a radiation and/or heavy-ion detector, but also in a space dust and/or space debri monitor on board a satellite [10–12]. On the other hand, further investigation is required to understand the production mechanism of the acoustic signal in piezoelectric PZT. Acknowledgments This study was carried out as part of the Research Project with Heavy Ions at NIRS-HIMAC. It was partly supported by grants-in-aid from JSPS and by ‘‘Groundbased Research Program for Utilization’’ of JSF. Fig. 5. Signal amplitudes of V0 p obtained from both SD and MD with changing rotation speed of chopper disk.
the signal amplitude is defined again as V0 p as indicated in Fig. 4. The V0 p obtained with changing rotation speed of the chopper disk is shown in Fig. 5. The error bar indicates correction due to the difference in electrostatic capacitance between SD and MD. It is found that the amplitudes were almost independent of the rotation speed. If the ions were uniformly distributed over the spill, the number of ions incident to the detector should be inversely proportional to the rotation speed [5]. Under this condition, the result may indicate that the sensitivity per ion increased with the rotation speed. On the other hand, it may be considered as a result of local depletion of the electrons in the path of the ions. Note that the signal amplitude explicitly depended on the rotation speed for the indirect method [3], that is, the case in which the absorber was a liquid material and the PZT detector was used exclusively as the sensor [3,4,8,9]. Therefore, our finding suggests that the production mechanism of output voltage is different between the direct and indirect methods. Besides, the amplitudes of MD are always larger than those of SD within the observed data even though the difference in the electrostatic capacitance is taken into consideration. This results reflects the effects of the multilayered structure. However, there are still no reliable theories that explain the production mechanism of the acoustic signal by radiation. It is required to further study the production mechanism from experimental and theoretical aspects. 4. Conclusions We investigated the potential of the piezoelectric PZT detector as a radiation detector based on acoustic principles. The effect of the multilayered structure on the sensitivity to the 400 MeV/n Xe beam was examined in comparison with the single-layered structure. The former was more sensitive than the latter. Fourier analysis proved that the output voltage was formed not of frequency
References [1] Th. Peterreins, F. Proebst, F.V. Feilitzsch, H. Kraus, in: G. Waysand, G. Chardin (Eds.), Tests of Nonequilibrium Phonon Detector, in Superconducting and Low-Temperature Particle Detectors, Elsevier Science Publishers B.V., North-Holland, 1989 p. 127. [2] T. Miyachi, N. Hasebe, H. Ito, T. Masumura, H. Okada, O. Okudaira, N. Yamashita, H. Yoshioka, M. Higuchi, T. Matsuyama, T. Murakami, Y. Uchihori, M. Kase, R. Kikuchi, M. Sato, T. Tou, Jpn. J. Appl. Phys. 42 (2003) 1456. [3] T. Miyachi, M. Fujii, N. Hasebe, G. Kuraza, S. Kobayashi, O. Okudaira, N. Yamashita, H. Shibata, T. Murakami, Y. Uchihori, 2005 Annual Report of the Research Project with Heavy Ions at NIRS-HIMAC, 2006, p. 330 [in Japanese]. [4] T. Miyachi, Y. Nakamura, G. Kuraza, M. Fujii, A. Nagashima, N. Hasebe, M.N. Kobayashi, S. Kobayashi, M. Miyajima, O. Okudaira, N. Yamashita, H. Shibata, T. Murakami, Y. Uchihori, N. Okada, T. Tou, Nucl. Instr. and Meth A 560 (2006) 606. [5] T. Miyachi, Y. Nakamura, G. Kuraza, M. Fujii, A. Nagashima, N. Hasebe, M.N. Kobayashi, S. Kobayashi, M. Miyajima, K. Mori, O. Okudaira, N. Yamashita, H. Shibata, T. Murakami, Y. Uchihori, N. Okada, Nucl. Instr. and Meth A 568 (2006) 760. [6] S. Takechi, T. Onishi, S. Minami, T. Miyachi, M. Fujii, N. Hasebe, K. Mori, H. Shibata, T. Murakami, Y. Uchihori, N. Okada, Jpn. J. Appl. Phys. 46 (2007) 1704. [7] Y. Hirao, H. Ogawa, S. Yamada, Y. Goto, T. Yamada, K. Sato, A. Itano, M. Kanazawa, K. Noda, K. Kawachi, M. Endo, T. Kanai, T. Kohno, M. Sudou, S. Minohara, A. Kitagawa, F. Soga, E. Takada, S. Watanabe, K. Endo, M. Kuwada, S. Matsumoto, Nucl. Phys. A 538 (1992) 541c. [8] L. Sulak, T. Armstrong, H. Baranger, M. Bergman, T. Bowen, A.E. Pier, P.A. Polakos, H. Bradner, A. Parvulescu, W.V. Jones, J. Learned, Nucl. Instr. Meth. 161 (1979) 203. [9] G.A. Askariyan, B.A. Dolgoshein, A.N. Kalinovsky, N.V. Mokhov, Nucl. Instr. Meth. 164 (1979) 267. [10] T. Miyachi, N. Hasebe, H. Ito, T. Masumura, H. Okada, H. Yoshioka, K. Nogami, T. Iwai, H. Shibata, Y. Hamabe, S. Sasaki, S. Sugita, S. Hasegawa, H. Yano, H. Ohashi, K. Muranaga, M. Sato, T. Tou, Adv. Space Res. 34 (2004) 935. [11] T. Miyachi, M. Fujii, N. Hasebe, M.N. Kobayashi, G. Kuraza, A. Nagashima, Y. Nakamura, K. Nogami, T. Iwai, S. Sasaki, H. Ohashi, S. Hasegawa, H. Yano, H. Shibata, Adv. Space Res. 35 (2005) 1263. [12] T. Miyachi, M. Fujii, N. Hasebe, M. Kobayashi, G. Kuraza, A. Nagashima, Y. Nakamura, O. Okudaira, N. Yamashita, K. Nogami, T. Iwai, S. Sasaki, H. Ohashi, S. Hasegawa, H. Yano, H. Shibata, N. Okada, T. Tou, J. Appl. Phys. 98 (2005) 014110.
Nuclear Instruments and Methods in Physics Research A 577 (2007) 741–744 www.elsevier.com/locate/nima
Evaluation of piezoelectric lead–zirconate–titanate multilayered detector by Fourier analysis Seiji Takechia,, Toshiyuki Onishia, Shigeyuki Minamia, Takashi Miyachib, Masayuki Fujiib, Nobuyuki Hasebeb, Kunishiro Morib, Hiromi Shibatac, Takeshi Murakamid, Yukio Uchihorid, Nagaya Okadae a Graduate School of Engineering, Osaka City University, Osaka 558-8585, Japan Advanced Research Institute for Science and Engineering, Waseda University, Tokyo 169-8555, Japan c Graduate School of Engineering, Kyoto University, Kyoto 606-8501, Japan d National Institute of Radiological Sciences, Chiba 263-8555, Japan e Honda Electronics Co. Ltd., Toyohashi, Aichi 441-3193, Japan
b
Received 22 March 2007; received in revised form 10 April 2007; accepted 13 April 2007 Available online 20 April 2007
Abstract Radiation detectors composed of lead–zirconate–titanate (PZT) were studied by directly irradiating them with a 400 MeV/n xenon beam. Fourier analysis revealed that frequency components of the output signal obtained from the detectors explicitly depended on the beam pulse duration. The sensitivity of the multilayered detector was discussed in comparison with that of a single-layered detector. r 2007 Elsevier B.V. All rights reserved. PACS: 29.40.n; 43.38.+n; 43.58.+z; 77.65.Ly Keywords: Lead–zirconate–titanate (PZT); Piezoelectric effect; Multilayers; Acoustic radiation detector
1. Introduction Up to now, radiation detectors have been operated on the basis of the principles of ionization and/or excitation in absorbing media. Besides these principles, phonon-associated processes have also been taken into account [1]. However, there are very few reports on detectors operated on the basis of elasticity at room temperature. We have been interested in radiation detectors based on the acoustic principle [2–6]. This report concerns the characteristics of a detector in which piezoelectric lead–zirconate–titanate (PZT) is used as the absorber as well as the sensor itself. In a previous study [6], we treated the general features of the multilayered structure in order to realize a highly sensitive detector. In this study, the characteristics of a multilayered detector were investigated through Fourier analysis of the Corresponding author. Tel.: +81 6 6605 2677; fax: +81 6 6690 2745.
E-mail address: [email protected] (S. Takechi). 0168-9002/$ - see front matter r 2007 Elsevier B.V. All rights reserved. doi:10.1016/j.nima.2007.04.137
output signal waveform. It was found that the power spectrum contained a higher frequency component as the beam pulse duration became shorter. As discussed in ref. [1], the sensitivity of the multilayered detector was better than that of a single-layered detector. Consequently, the results of Fourier analysis provide insight into the production mechanism of output voltage. Since there are very few reports on such a production mechanism, the presented data were considered to be worth reporting to improve the detector that is based on the acoustic principle at room temperature.
2. Experimental method 2.1. Detectors Since we are interested in piezoelectricity, two types of detectors were used: single-layered and multilayered detectors. The detector thickness was determined to be
ARTICLE IN PRESS S. Takechi et al. / Nuclear Instruments and Methods in Physics Research A 577 (2007) 741–744
742
8 mm in order to confine 400 MeV/n xenon ions, the range of which is 7.8 mm in PZT. The single-layered detector was fabricated with homogeneously baked PZT that was 20 mm in diameter. Hereafter, this detector is referred to as the single-layered detector (SD). The multilayered detector was fabricated by stacking 80-mm-thick PZT disks of 20 mm diameter. A 2-mm-thick metal sheet that was made of Ag–Pd was sandwiched between disks. One hundred disks were joined by baking. Hereafter, this detector is referred to as the multilayered detector (MD). Silver electrodes with a thickness of a few mm were coated onto both flat surfaces. Both detectors were polarized in the direction normal to the flat surface. The electrostatic capacitance of SD was 770 pF and that of MD was 650 pF.
chopper. The beam intensity was monitored by the counter. A frame made of epoxy resin supported the detector. The frame was suspended by four springs to prevent noise arising from mechanical disturbances. Moreover, in order to eliminate noise originating from the variation in atmospheric pressure, the detector was set in a closed chamber in which the internal pressure was maintained below 1 Torr. The chamber, which was made from transparent acrylic resin to enable visual confirmation of the alignment, was placed 18 cm downstream of the scintillation counter. The signal obtained from the detector was processed with an amplifier, and then transferred to a digital oscilloscope. The processed signal was averaged over 100 events in the oscilloscope to suppress the effects of random noise. Digitally processed data were stored in a personal computer.
2.2. Experimental setup 3. Results and discussion The experimental arrangement is schematically shown in Fig. 1. A 400 MeV/n Xe beam was supplied by the Heavy Ion Medical Accelerator in Chiba (HIMAC) at the National Institute of Radiological Sciences [7]. The beam was originally extracted for 0.3 s within a period of 3.3 s. We adopted a chopper to obtain a short pulsed beam. The chopper was a rotating stainless-steel disk with a diameter of 30 cm and a thickness of 10 mm, in which four slits with a length of 10 mm and a width of 1 mm were perforated in an equiangular manner. The disk was installed 73 cm downstream of the exit of the beam duct. By adjusting the rotation speed, the beam intensity could be varied in accordance with the change in the pulse duration from 50 to 200 ms [5]. When the rotation speed was 30 rps, the beam duration became 120 ms and the typical number of xenon ions was 200 per slit window. A 1-mm-thick plastic scintillation counter was placed 34 cm downstream of the
SCALER PC Disc. Oscilloscope PMT
Amplifier
PZT Beam Chamber Chopper
Scintillator
Slit
Disk Fig. 1. Schematic view of experimental configuration. Here, photomultiplier is indicated as PMT, discriminator as Disc., and personal computer as PC.
We have investigated the response of the two types of PZT detectors to a 400 MeV/n Xe beam, changing the beam pulse duration by adjusting the rotation speed of the chopper disk. Fig. 2(a) shows the output signal obtained from the photomultiplier when the chopper disk rotated at 45 rps. The signal appeared at the time when the beam passed through the slit. The pulse duration was recognized to be 100 ms. The waveforms of output voltage observed from SD and MD are shown in Figs. 2(b) and (c), respectively. Here, the output amplitude is defined as Vp indicated in the figures. It can be seen that Vp obtained from MD was larger than that from SD. It is found that MD is more sensitive to the high-energy xenon ion beam than SD under these experimental conditions. Next, signal waveforms observed from both SD and MD were analyzed by Fourier transformation. The frequency distribution from 1 kHz to 500 MHz was examined. Fig. 3(a) shows the power spectrum distribution up to 100 kHz, obtained from data in Figs. 2(b) and (c). Note that no significant spectrum appeared at any frequency beyond 100 kHz. It can be seen from Fig. 3(a) that a peak appeared at 89 kHz when SD was used. Similar peaks were observed only from SD at any rotation speed within this experimental condition. A PZT disk 20 mm in diameter has a fundamental resonant frequency of 90 kHz toward the radial direction, which corresponds to the transverse waves propagating in the PZT. The time when the peak frequency appears was examined through continuous wavelet transformation. However, localization on the time axis for frequency was not recognized in the transformed plot. Therefore, the frequency component is considered to be that from noise. One of the reasons why the waveform observed from MD did not contain the above frequency component may be due to difference in the impedance between SD and MD. Fig. 3(b) shows the power spectra obtained from MD at various rotation speeds. Here, each power spectrum was normalized to each maximum value obtained at 1 kHz. It is found that the signal contained
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Fig. 3. Power spectra from 1 to 100 kHz obtained by Fourier transformation (a) of data from Figs. 2(b) and (c) and Fig. 3(b) of data from MD when chopper disk rotated at 15, 30, and 45 rps.
Fig. 2. Typical waveforms of output signal observed from (a) photomultiplier, (b) SD, and (c) MD when chopper disk rotated at 45 rps.
higher frequency components as the rotation speed increased. This indicates that the variation of the beam pulse frequency was directly reflected in the output voltage observed from the detectors. It is also found that the spectra within 20 kHz obtained from MD are larger than those from SD under these experimental conditions. Note that the beam pulse frequency lay within 20 kHz. Fig. 4 shows the curves reconstructed by inverse Fourier transformation from the frequency components below 20 kHz in Fig. 3(a). These waveforms hold almost the same shape as shown in Figs. 2(b) and (c). This implies that the resonant frequency components did not contribute to the output voltage observed from the PZT detector. Here,
Fig. 4. Output waveforms reconstructed by inverse Fourier transformation when chopper disk rotated at 45 rps. Only frequency components below 20 kHz were used.
ARTICLE IN PRESS 744
S. Takechi et al. / Nuclear Instruments and Methods in Physics Research A 577 (2007) 741–744
components inherent to the PZT detector but of those dependent on the beam pulse duration. It was also found that the sensitivity was independent of the rotation speed. These results are useful for the application of PZT not only in a radiation and/or heavy-ion detector, but also in a space dust and/or space debri monitor on board a satellite [10–12]. On the other hand, further investigation is required to understand the production mechanism of the acoustic signal in piezoelectric PZT. Acknowledgments This study was carried out as part of the Research Project with Heavy Ions at NIRS-HIMAC. It was partly supported by grants-in-aid from JSPS and by ‘‘Groundbased Research Program for Utilization’’ of JSF. Fig. 5. Signal amplitudes of V0 p obtained from both SD and MD with changing rotation speed of chopper disk.
the signal amplitude is defined again as V0 p as indicated in Fig. 4. The V0 p obtained with changing rotation speed of the chopper disk is shown in Fig. 5. The error bar indicates correction due to the difference in electrostatic capacitance between SD and MD. It is found that the amplitudes were almost independent of the rotation speed. If the ions were uniformly distributed over the spill, the number of ions incident to the detector should be inversely proportional to the rotation speed [5]. Under this condition, the result may indicate that the sensitivity per ion increased with the rotation speed. On the other hand, it may be considered as a result of local depletion of the electrons in the path of the ions. Note that the signal amplitude explicitly depended on the rotation speed for the indirect method [3], that is, the case in which the absorber was a liquid material and the PZT detector was used exclusively as the sensor [3,4,8,9]. Therefore, our finding suggests that the production mechanism of output voltage is different between the direct and indirect methods. Besides, the amplitudes of MD are always larger than those of SD within the observed data even though the difference in the electrostatic capacitance is taken into consideration. This results reflects the effects of the multilayered structure. However, there are still no reliable theories that explain the production mechanism of the acoustic signal by radiation. It is required to further study the production mechanism from experimental and theoretical aspects. 4. Conclusions We investigated the potential of the piezoelectric PZT detector as a radiation detector based on acoustic principles. The effect of the multilayered structure on the sensitivity to the 400 MeV/n Xe beam was examined in comparison with the single-layered structure. The former was more sensitive than the latter. Fourier analysis proved that the output voltage was formed not of frequency
References [1] Th. Peterreins, F. Proebst, F.V. Feilitzsch, H. Kraus, in: G. Waysand, G. Chardin (Eds.), Tests of Nonequilibrium Phonon Detector, in Superconducting and Low-Temperature Particle Detectors, Elsevier Science Publishers B.V., North-Holland, 1989 p. 127. [2] T. Miyachi, N. Hasebe, H. Ito, T. Masumura, H. Okada, O. Okudaira, N. Yamashita, H. Yoshioka, M. Higuchi, T. Matsuyama, T. Murakami, Y. Uchihori, M. Kase, R. Kikuchi, M. Sato, T. Tou, Jpn. J. Appl. Phys. 42 (2003) 1456. [3] T. Miyachi, M. Fujii, N. Hasebe, G. Kuraza, S. Kobayashi, O. Okudaira, N. Yamashita, H. Shibata, T. Murakami, Y. Uchihori, 2005 Annual Report of the Research Project with Heavy Ions at NIRS-HIMAC, 2006, p. 330 [in Japanese]. [4] T. Miyachi, Y. Nakamura, G. Kuraza, M. Fujii, A. Nagashima, N. Hasebe, M.N. Kobayashi, S. Kobayashi, M. Miyajima, O. Okudaira, N. Yamashita, H. Shibata, T. Murakami, Y. Uchihori, N. Okada, T. Tou, Nucl. Instr. and Meth A 560 (2006) 606. [5] T. Miyachi, Y. Nakamura, G. Kuraza, M. Fujii, A. Nagashima, N. Hasebe, M.N. Kobayashi, S. Kobayashi, M. Miyajima, K. Mori, O. Okudaira, N. Yamashita, H. Shibata, T. Murakami, Y. Uchihori, N. Okada, Nucl. Instr. and Meth A 568 (2006) 760. [6] S. Takechi, T. Onishi, S. Minami, T. Miyachi, M. Fujii, N. Hasebe, K. Mori, H. Shibata, T. Murakami, Y. Uchihori, N. Okada, Jpn. J. Appl. Phys. 46 (2007) 1704. [7] Y. Hirao, H. Ogawa, S. Yamada, Y. Goto, T. Yamada, K. Sato, A. Itano, M. Kanazawa, K. Noda, K. Kawachi, M. Endo, T. Kanai, T. Kohno, M. Sudou, S. Minohara, A. Kitagawa, F. Soga, E. Takada, S. Watanabe, K. Endo, M. Kuwada, S. Matsumoto, Nucl. Phys. A 538 (1992) 541c. [8] L. Sulak, T. Armstrong, H. Baranger, M. Bergman, T. Bowen, A.E. Pier, P.A. Polakos, H. Bradner, A. Parvulescu, W.V. Jones, J. Learned, Nucl. Instr. Meth. 161 (1979) 203. [9] G.A. Askariyan, B.A. Dolgoshein, A.N. Kalinovsky, N.V. Mokhov, Nucl. Instr. Meth. 164 (1979) 267. [10] T. Miyachi, N. Hasebe, H. Ito, T. Masumura, H. Okada, H. Yoshioka, K. Nogami, T. Iwai, H. Shibata, Y. Hamabe, S. Sasaki, S. Sugita, S. Hasegawa, H. Yano, H. Ohashi, K. Muranaga, M. Sato, T. Tou, Adv. Space Res. 34 (2004) 935. [11] T. Miyachi, M. Fujii, N. Hasebe, M.N. Kobayashi, G. Kuraza, A. Nagashima, Y. Nakamura, K. Nogami, T. Iwai, S. Sasaki, H. Ohashi, S. Hasegawa, H. Yano, H. Shibata, Adv. Space Res. 35 (2005) 1263. [12] T. Miyachi, M. Fujii, N. Hasebe, M. Kobayashi, G. Kuraza, A. Nagashima, Y. Nakamura, O. Okudaira, N. Yamashita, K. Nogami, T. Iwai, S. Sasaki, H. Ohashi, S. Hasegawa, H. Yano, H. Shibata, N. Okada, T. Tou, J. Appl. Phys. 98 (2005) 014110.