論文 - 武田 彩希
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X-ray response evaluation in subpixel level for X-ray SOI pixel detectors 査読あり
Negishi K., Kohmura T., Hagino K., Kogiso T., Oono K., Yarita K., Sasaki A., Tamasawa K., Go Tsuru T., Tanaka T., Matsumura H., Tachibana K., Hayashi H., Harada S., Mori K., Takeda A., Nishioka Y., Takebayashi N., Yokoyama S., Fukuda K., Arai Y., Miyoshi T., Kishimoto S., Kurachi I.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 924 462 - 467 2019年4月
記述言語:英語 掲載種別:研究論文(学術雑誌) 出版者・発行元:Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
© 2018 Elsevier B.V. We have been developing event-driven SOI Pixel Detectors, named “XRPIX” (X-ray soiPIXel) based on the silicon-on-insulator (SOI) pixel technology, for the future X-ray astronomical satellite with wide band coverage from 0.5keV to 40keV. XRPIX has event trigger output function at each pixel to acquire a good time resolution of a few μs and has Correlated Double Sampling function to reduce electric noises. The good time resolution enables the XRPIX to reduce Non X-ray Background in the high energy band above 10keV drastically by using anti-coincidence technique with active shield counters surrounding XRPIX. In order to increase the soft X-ray sensitivity, it is necessary to make the dead layer on the X-ray incident surface as thin as possible. Since XRPIX1b, which is a device at the initial stage of development, is a front-illuminated (FI) type of XRPIX, low energy X-ray photons are absorbed in the 8μm thick circuit layer, lowering the sensitivity in the soft X-ray band. Therefore, we developed a back-illuminated (BI) device XRPIX2b, and confirmed high detection efficiency down to 2.6keV, below which the efficiency is affected by the readout noise. In order to further improve the detection efficiency in the soft X-ray band, we developed a back-illuminated device XRPIX3b with lower readout noise. In this work, we irradiated 2–5keV X-ray beam collimated to 4μmϕ to the sensor layer side of the XRPIX3b at 6μm pitch. In this paper, we reported the uniformity of the relative detection efficiency, gain and energy resolution in the subpixel level for the first time. We also confirmed that the variation in the relative detection efficiency at the subpixel level reported by Matsumura (2015) has improved.
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Total ionizing dose effects on the SOI pixel sensor for X-ray astronomical use 査読あり
Mori K., Nishioka Y., Takeda A., Takebayashi N., Takenaka R., Sakakura S., Yokoyama S., Fukuda K., Yukumoto M., Hida T., Tsuru T., Tanaka T., Matsumura H., Hayashi H., Kohmura T., Nakashima S., Arai Y., Kurachi I.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 924 473 - 479 2019年4月
記述言語:英語 掲載種別:研究論文(学術雑誌) 出版者・発行元:Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
© 2018 Elsevier B.V. We report on total ionizing dose effects on the X-ray SOI pixel sensor, XRPIX. XRPIX has been developed as an imaging spectrometer for X-ray astronomical use in space. Front- and back-illuminated (FI and BI) devices were irradiated with hard X-rays from an X-ray tube operated at 30 kV with a Molybdenum target. We found that the degradation rate of the readout noise of the BI device was approximately three times slower than that of the FI device as a function of radiation exposure. Those of both type of devices, however, were virtually identical when the readout noise was evaluated as a function of the absorbed dose at the buried oxide layer, D BOX . The pedestal and analog-to-digital conversion gain also displayed similar tendencies. These results demonstrate that BI type devices have a higher radiation tolerance as a focal plane sensor of an X-ray mirror and the radiation tolerance of XRPIX devices is governed by D BOX . The readout noise was stable up to about 1 krad in D BOX , increased by about 10% at 10 krad in D BOX , and continued to increase under further irradiation. If we employ an X-ray mirror with a half-power diameter of 10 arcsec and a focal length of 10 m, 10 krad in D BOX , a reasonable threshold of radiation tolerance in this experiment, is equivalent to more than three years in orbit, typically required of space-borne sensors.
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Studies of radioactive background in SOI pixel detector for solar axion search experiment 査読あり
Onuki Y., Grimaldo J., Ose T., Aihara H., Inoue Y., Kamiya Y., Shimazoe K., Tsuru T., Tanaka T., Miuchi K., Takeda A., Arai Y.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 924 448 - 451 2019年4月
記述言語:英語 掲載種別:研究論文(学術雑誌) 出版者・発行元:Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
© 2018 Elsevier B.V. An application of a modern noble pixel detector, XRPIX series, for solar KSVZ axion search experiment is being developed. A low radioactive background is necessary in the detector volume for the axion search. We surveyed the radioactivity of all peripheral components mounted on the detector using an HPGe detector. The results are used as an input for a GEANT4 Monte Carlo simulation to study the background in the experiment. This paper describes the expected background and the simulated sensitivity of stacked XRPIX detector currently under development.
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Proton radiation damage experiment for X-ray SOI pixel detectors 査読あり
Yarita K., Kohmura T., Hagino K., Kogiso T., Oono K., Negishi K., Tamasawa K., Sasaki A., Yoshiki S., Tsuru T., Tanaka T., Matsumura H., Tachibana K., Hayashi H., Harada S., Takeda A., Mori K., Nishioka Y., Takebayashi N., Yokoyama S., Fukuda K., Arai Y., Miyoshi T., Kurachi I., Hamano T.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 924 457 - 461 2019年4月
記述言語:英語 掲載種別:研究論文(学術雑誌) 出版者・発行元:Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
© 2018 Elsevier B.V. In low earth orbit, there are many cosmic rays composed primarily of high energy protons. These cosmic rays cause surface and bulk radiation effects, resulting in degradation of detector performance. Quantitative evaluation of radiation hardness is essential in development of X-ray detectors for astronomical satellites. We performed proton irradiation experiments on newly developed X-ray detectors called XRPIX based on silicon-on-insulator technology at HIMAC in National Institute of Radiological Sciences. We irradiated 6 MeV protons with a total dose of 0.5 krad, equivalent to 6 years irradiation in orbit. As a result, the gain increases by 0.2% and the energy resolution degrades by 0.5%. Finally we irradiated protons up to 20 krad and found that detector performance degraded significantly at 5 krad. With 5 krad irradiation corresponding to 60 years in orbit, the gain increases by 0.7% and the energy resolution worsens by 10%. By decomposing into noise components, we found that the increase of the circuit noise is dominant in the degradation of the energy resolution.
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Harada S., Tsuru T., Tanaka T., Uchida H., Matsumura H., Tachibana K., Hayashi H., Takeda A., Mori K., Nishioka Y., Takebayashi N., Yokoyama S., Fukuda K., Arai Y., Kurachi I., Kawahito S., Kagawa K., Yasutomi K., Shrestha S., Nakanishi S., Kamehama H., Kohmura T., Hagino K., Negishi K., Oono K., Yarita K.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 924 468 - 472 2019年4月
記述言語:英語 掲載種別:研究論文(学術雑誌) 出版者・発行元:Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
© 2018 Elsevier B.V. We have been developing event driven X-ray Silicon-On-Insulator (SOI) pixel sensors, called “XRPIX” for the next generation of X-ray astronomy satellites. XRPIX is a monolithic active pixel sensor, fabricated using the SOI CMOS technology, and is equipped with the so-called “Event-Driven readout” which allows reading out only hit pixels by using the trigger circuit implemented in each pixel. The current version of XRPIX has lower spectral performance in the Event-Driven readout mode than in the Frame readout mode, which is due to the interference between the sensor layer and the circuit layer. The interference also lowers the gain. In order to suppress the interference, we developed a new device, “XRPIX6E” equipped with the Pinned Depleted Diode structure. A sufficiently highly-doped buried p-well is formed at the interface between the buried oxide layer and the sensor layer, and acts as a shield layer. XRPIX6E exhibits improved spectral performances both in the Event-Driven readout mode and in the Frame readout mode in comparison to previous devices. The energy resolutions in full width at half maximum at 6.4 keV are 236 ± 1 eV and 335 ± 4 eV in the Frame and Event-Driven readout modes, respectively. There are differences between the readout noise and the spectral performance in the two modes, which suggests that some mechanism still degrades the performance in the Event-Driven readout mode.
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Kanemaru Y., Sato J., Mori K., Nakajima H., Nishioka Y., Takeda A., Hayashida K., Matsumoto H., Iwagaki J., Okazaki K., Asakura K., Yoneyama T., Uchida H., Okon H., Tanaka T., Tsuru T., Tomida H., Shimoi T., Kohmura T., Hagino K., Murakami H., Kobayashi S., Yamauchi M., Hatsukade I., Nobukawa M., Nobukawa K., Hiraga J., Uchiyama H., Yamaoka K., Ozaki M., Dotani T., Tsunemi H., Hamano T.
Journal of Instrumentation 14 ( 4 ) 2019年4月
記述言語:英語 掲載種別:研究論文(学術雑誌) 出版者・発行元:Journal of Instrumentation
© 2019 IOP Publishing Ltd and Sissa Medialab. We report the radiation hardness of a p-channel CCD developed for the X-ray CCD camera onboard the XRISM satellite. This CCD has basically the same characteristics as the one used in the previous Hitomi satellite, but newly employs a notch structure of potential for signal charges by increasing the implant concentration in the channel . The new device was exposed up to approximately 7.9 × 1010 protons cm-2 at 100 MeV . The charge transfer inefficiency was estimated as a function of proton fluence with an 55Fe source. A device without the notch structure was also examined for comparison. The result shows that the notch device has a significantly higher radiation hardness than those without the notch structure including the device adopted for Hitomi. This proves that the new CCD is radiation tolerant for space applications with a sufficient margin.
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Kagaya M., Katagiri H., Tojo N., Kato R., Tsuru T.G., Takeda A., Arai Y.
2018 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2018 - Proceedings 2018年11月
記述言語:英語 掲載種別:研究論文(学術雑誌) 出版者・発行元:2018 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2018 - Proceedings
© 2018 IEEE. In the fields of astrophysics and nuclear medicine diagnostics, the use of a 511-keV line gamma rays probe is indispensable. Compton-imaging techniques are suitable for measuring 511-keV line gamma rays because of the high probability of Compton scattering at this energy level. However, a reconstructed image obtained by a traditional Compton camera has false spots because this camera reconstructs an image with smeared rings. On the other hand, an advanced Compton camera can enhance the angular resolution and reduce the background by detecting recoil electron tracks. We focus on a silicon-on-insulator (SOI) pixel sensor with 30 m cells because of its small pixel pitch and high-energy resolution. In this study, we developed a prototype of an advanced Compton camera using an SOI sensor and evaluated its performance for detecting the recoil electron tracks of 511-keV gamma rays.
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Performance of SOI Pixel Sensors Developed for X-ray Astronomy
Tanaka T., Tsuru T.G., Uchida H., Harada S., Okuno T., Kayama K., Amano Y., Matsumura H., Takeda A., Mori K., Nishioka Y., Fukuda K., Hida T., Yukumoto M., Arai Y., Kurachi I., Kawahito S., Kagawa K., Yasutomi K., Shrestha S., Nakanishi S., Kamehama H., Kohmura T., Hagino K., Negishi K., Oono K., Yarita K.
2018 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2018 - Proceedings 2018年11月
記述言語:英語 掲載種別:研究論文(学術雑誌) 出版者・発行元:2018 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2018 - Proceedings
© 2018 IEEE. We have been developing monolithic active pixel sensors for X-rays based on the silicon-on-insulator technology. Our device consists of a low-resistivity Si layer for readout CMOS electronics, a high-resistivity Si sensor layer, and a SiO2 layer between them. This configuration allows us both high-speed readout circuits and a thick (on the order of 100 m) depletion layer in a monolithic device. Each pixel circuit contains a trigger output function, with which we can achieve a time resolution of ≲ 10 s. One of our key development items is improvement of the energy resolution. We recently fabricated a device named XRPIX6E, to which we introduced a pinned depleted diode (PDD) structure. The structure reduces the capacitance coupling between the sensing area in the sensor layer and the pixel circuit, which degrades the spectral performance. With XRPIX6E, we achieve an energy resolution of ~ 150 eV in full width at half maximum for 6.4-keV X-rays. In addition to the good energy resolution, a large imaging area is required for practical use. We developed and tested XRPIX5b, which has an imaging area size of 21.9 mm 13.8 mm and is the largest device that we ever fabricated. We successfully obtain X-ray data from almost all the 608 384 pixels with high uniformity.
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Shrestha S., Kawahito S., Kamehama H., Nakanishi S., Yasutomi K., Kagawa K., Teranishi N., Takeda A., Tsuru T., Kurachi I., Arai Y.
Sensors (Switzerland) 18 ( 6 ) 2018年6月
記述言語:英語 掲載種別:研究論文(学術雑誌) 出版者・発行元:Sensors (Switzerland)
© 2018 by the authors. Licensee MDPI, Basel, Switzerland. In this paper, we report on the development of a monolithic active pixel sensor for X-ray imaging using 0.2 µm fully depleted silicon-on-insulator (SOI)-based technology to support next generation astronomical satellite missions. Detail regarding low-noise dual-gain SOI based pixels with a charge sensitive amplifier and pinned depleted diode sensor structure is presented. The proposed multi-well sensor structure underneath the fully-depleted SOI allows the design of a detector with low node capacitance and high charge collection efficiency. Configurations for achieving very high charge-to-voltage conversion gain of 52 µV/e− and 187 µV/e− are demonstrated. Furthermore, in-pixel dual gain selection is used for low-noise and wide dynamic range X-ray energy detection. A technique to improve the noise performance by removing correlated system noise leads to an improvement in the spectroscopic performance of the measured X-ray energy. Taken together, the implemented chip has low dark current (44.8 pA/cm2 at −30°C), improved noise performance (8.5 e− rms for high gain and 11.7 e− rms for low gain), and better energy resolution of 2.89% (171 eV FWHM) at 5.9 keV using55 Fe and 1.67% (234 eV FWHM) at 13.95 keV using241 Am.
DOI: 10.3390/s18061789
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Kamehama H., Kawahito S., Shrestha S., Nakanishi S., Yasutomi K., Takeda A., Tsuru T., Arai Y.
Sensors (Switzerland) 18 ( 1 ) 2018年1月
記述言語:英語 掲載種別:研究論文(学術雑誌) 出版者・発行元:Sensors (Switzerland)
© 2017 by the authors. Licensee MDPI, Basel, Switzerland. This paper presents a novel full-depletion Si X-ray detector based on silicon-on-insulator pixel (SOIPIX) technology using a pinned depleted diode structure, named the SOIPIX-PDD. The SOIPIX-PDD greatly reduces stray capacitance at the charge sensing node, the dark current of the detector, and capacitive coupling between the sensing node and SOI circuits. These features of the SOIPIX-PDD lead to low read noise, resulting high X-ray energy resolution and stable operation of the pixel. The back-gate surface pinning structure using neutralized p-well at the back-gate surface and depleted n-well underneath the p-well for all the pixel area other than the charge sensing node is also essential for preventing hole injection from the p-well by making the potential barrier to hole, reducing dark current from the Si-SiO2 interface and creating lateral drift field to gather signal electrons in the pixel area into the small charge sensing node. A prototype chip using 0.2 µm SOI technology shows very low readout noise of 11.0 e-rms, low dark current density of 56 pA/cm2 at -35°C and the energy resolution of 200 eV(FWHM) at 5.9 keV and 280 eV (FWHM) at 13.95 keV.
DOI: 10.3390/s18010027
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Kyoto's event-driven x-ray astronomy SOI pixel sensor for the FORCE mission
Tsuru T., Hayashi H., Tachibana K., Harada S., Uchida H., Tanaka T., Arai Y., Kurachi I., Mori K., Takeda A., Nishioka Y., Takebayashi N., Yokoyama S., Fukuda K., Kohmura T., Hagino K., Ohno K., Negishi K., Yarita K., Kawahito S., Kagawa K., Yasutomi K., Shrestha S., Nakanishi S., Kamehama H., Matsumura H.
Proceedings of SPIE - The International Society for Optical Engineering 10709 2018年
記述言語:英語 掲載種別:研究論文(学術雑誌) 出版者・発行元:Proceedings of SPIE - The International Society for Optical Engineering
© 2018 SPIE. We have been developing monolithic active pixel sensors, X-ray Astronomy SOI pixel sensors, XRPIXs, based on a Silicon-On-Insulator (SOI) CMOS technology as soft X-ray sensors for a future Japanese mission, FORCE (Focusing On Relativistic universe and Cosmic Evolution). The mission is characterized by broadband (1-80 keV) X-ray imaging spectroscopy with high angular resolution (< 15 arcsec), with which we can achieve about ten times higher sensitivity in comparison to the previous missions above 10 keV. Immediate readout of only those pixels hit by an X-ray is available by an event trigger output function implemented in each pixel with the time resolution higher than 10 μsec (Event-Driven readout mode). It allows us to do fast timing observation and also reduces non-X-ray background dominating at a high X-ray energy band above 5{10 keV by adopting an anti-coincidence technique. In this paper, we introduce our latest results from the developments of the XRPIXs. (1) We successfully developed a 3-side buttable back-side illumination device with an imaging area size of 21.9 mm × 13.8 mm and an pixel size of 36 μm × 36 μm. The X-ray throughput with the device reaches higher than 0.57 kHz in the Event-Driven readout mode. (2) We developed a device using the double SOI structure and found that the structure improves the spectral performance in the Event-Driven readout mode by suppressing the capacitive coupling interference between the sensor and circuit layers. (3) We also developed a new device equipped with the Pinned Depleted Diode structure and confirmed that the structure reduces the dark current generated at the interface region between the sensor and the SiO2 insulator layers. The device shows an energy resolution of 216 eV in FWHM at 6.4 keV in the Event-Driven readout mode.
DOI: 10.1117/12.2312098
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Soft x-ray imaging telescope (Xtend) onboard X-ray Astronomy Recovery Mission (XARM)
Hayashida K., Tomida H., Mori K., Nakajima H., Tanaka T., Uchida H., Tsuru T., Murakami H., Okajima T., Kohmura T., Hagino K., Kobayashi S., Ishida M., Maeda Y., Uchiyama H., Yamaoka K., Matsumoto H., Nobukawa M., Nobukawa K., Hiraga J., Yamauchi M., Hatsukade I., Soong Y., Mori H., Hayashi T., Tsunemi H., Ozaki M., Dotani T., Iwagaki J., Yoneyama T., Okazaki K., Asakura K., Onishi S., Kanemaru Y., Sato J., Nishioka Y., Takeda A., Okon H., Yoshida M., Shimoi T.
Proceedings of SPIE - The International Society for Optical Engineering 10699 2018年
記述言語:日本語 掲載種別:研究論文(学術雑誌) 出版者・発行元:Proceedings of SPIE - The International Society for Optical Engineering
© 2018 SPIE. X-ray Astronomy Recovery Mission (XARM) scheduled to be launched in early 2020's carries two soft X-ray telescopes. One is Resolve consisting of a soft X-ray mirror and a micro calorimeter array, and the other is Soft X-ray Imaging Telescope (Xtend), a combination of an X-ray mirror assembly (XMA) and an X-ray CCD camera (SXI). Xtend covers a field of view (FOV) of 38′ × 38′, much larger than that of Resolve (3′ × 3 ′) with moderate energy resolution in the energy band from 0.4 keV to 13 keV, which is similar to that of Resolve (from 0.3 keV to 12 keV). Simultaneous observations of both telescopes provide complimentary data of X-ray sources in their FOV. In particular, monitoring X-ray sources outside the Resolve FOV but inside the Xtend FOV is important to enhance the reliability of super high resolution spectra obtained with Resolve. Xtend is also expected to be one of the best instruments for low surface brightness X-ray emissions with its low non X-ray background level, which is comparable to that of Suzaku XIS. The design of Xtend is almost identical to those of Soft X-ray Telescope (SXT) and Soft X-ray Imager (SXI) both on board the Hitomi satellite. However, several mandatory updates are included. Updates for the CCD chips are verified with experiment using test CCD chips before finalizing the design of the flight model CCD. Fabrication of the foils for XMA has started, and flight model production of the SXI is almost ready.
DOI: 10.1117/12.2311446
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Development of electron-tracking Compton imaging system with 30-μm SOI pixel sensor
Yoshihara Y., Shimazoe K., Mizumachi Y., Takahashi H., Kamada K., Takeda A., Tsuru T., Arai Y.
Journal of Instrumentation 12 ( 1 ) 2017年1月
記述言語:日本語 掲載種別:研究論文(学術雑誌) 出版者・発行元:Journal of Instrumentation
© 2017 IOP Publishing Ltd and Sissa Medialab srl. Compton imaging is a useful method to localize gamma sources without using mechanical collimators. In conventional Compton imaging, the incident directions of gamma rays are estimated in a cone for each event by analyzing the sequence of interactions of each gamma ray followed by Compton kinematics. Since the information of the ejection directions of the recoil electrons is lost, many artifacts in the shape of cone traces are generated, which reduces signal-to-noise ratio (SNR) and angular resolution. We have developed an advanced Compton imaging system with the capability of tracking recoil electrons by using a combination of a trigger-mode silicon-on-insulator (SOI) pixel detector and a GAGG detector. This system covers the 660-1330 keV energy range for localization of contamination nuclides such as 137Cs and 134Cs inside the Fukushima Daiichi Nuclear Power Plant in Japan. The ejection directions of recoil electrons caused by Compton scattering are detected on the micro-pixelated SOI detector, which can theoretically be used to determine the incident directions of the gamma rays in a line for each event and can reduce the appearance of artifacts. We obtained 2-D reconstructed images from the first iteration of the proposed system for 137Cs, and the SNR and angular resolution were enhanced compared with those of conventional Compton imaging systems.
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Ohmura S., Tsuru T., Tanaka T., Uchida H., Takeda A., Matsumura H., Ito M., Arai Y., Kurachi I., Miyoshi T., Nakashima S., Mori K., Nishioka Y., Takebayashi N., Noda K., Kohmura T., Tamasawa K., Ozawa Y., Sato T., Konno T., Kawahito S., Kagawa K., Yasutomi K., Kamehama H., Shrestha S., Hara K., Honda S.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 831 61 - 64 2016年9月
記述言語:日本語 掲載種別:研究論文(学術雑誌) 出版者・発行元:Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
© 2016 Elsevier B.V. We have been developing silicon-on-insulator pixel sensors, “XRPIXs,” for future X-ray astronomy satellites. XRPIXs are equipped with a function of “event-driven readout,” with which we can read out only hit pixels by trigger signals and hence realize good time resolution reaching ∼10μs. The current version of XRPIX suffers from a problem that the spectral performance degrades in the event-driven readout mode compared to the frame-readout mode, in which all the pixels are read out serially. Previous studies have clarified that one of the causes is capacitive coupling between the sense node and the trigger signal line in the circuit layer. In order to solve the problem, we adopt the Double SOI structure having a middle silicon layer between the circuit and the sensor layers. We expect the middle silicon layer to work as an electrostatic shield and reduces the capacitive coupling. In this paper, we report the spectroscopic performance of XRPIX with the middle silicon layer. We successfully reduce the capacitive coupling and the readout noise.
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The first back-side illuminated types of Kyoto's X-ray astronomy SOIPIX
Itou M., Tsuru T., Tanaka T., Takeda A., Matsumura H., Ohmura S., Uchida H., Nakashima S., Arai Y., Kurachi I., Mori K., Takenaka R., Nishioka Y., Kohmura T., Tamasawa K., Tindall C.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 831 55 - 60 2016年9月
記述言語:日本語 掲載種別:研究論文(学術雑誌) 出版者・発行元:Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
© 2016 Elsevier B.V. We have been developing Kyoto's X-ray astronomy SOI pixel sensors, called “XRPIX”, aiming to extend the frontiers of X-ray astronomy with the wide-band imaging spectroscopy in the 0.5–40 keV band. A dead layer on the X-ray incident surface should ideally be as thin as possible to achieve a high sensitivity below 1 keV, and the depletion layer is required to be thick enough to detect 40 keV X-rays. Thus, we have started developing fully-depleted back-side illuminated (BI) types of XRPIXs. This paper reports on our first two BI devices and their X-ray evaluation (2.6–12 keV). The device named “XRPIX2b-FZ-LA” successfully reaches a full depletion with a thickness of 500 μm. On the other hand, it has a dead layer with a thickness of 1.1–1.5 μm and struggles to achieve the requirement of 1.0 μm. The other device named “XRPIX2b-CZ-PZ”, which is applied with a thin Si sensor-layer and an improved back-side process, is found to satisfy the requirement with its thickness of 0.9–1.0 μm, including Al optical blocking filter of 0.2 μm, although the Si sensor-layer is rather thin with 62 μm. We also describe in this paper the X-ray calibration system that we have built for the X-ray evaluation of XRPIXs.
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Radiation damage in transistors fabricated with lapis semiconductor 200 nm FD-SOI technology
Glab S., Arai Y., Baszczyk M., Bugiel S., Dasgupta R., Dorosz P., Idzik M., Kapusta P., Kucewicz W., Mierzwinska G., Mik L., Miyoshi T., Ptaszkiewicz M., Rydygier M., Sapor M., Swakon J., Takeda A.
2014 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2014 2016年3月
記述言語:日本語 掲載種別:研究論文(学術雑誌) 出版者・発行元:2014 IEEE Nuclear Science Symposium and Medical Imaging Conference, NSS/MIC 2014
© 2014 IEEE. The paper presents radiation tolerance of the transistor TEG (TrTEG5) test structure fabricated in 200 nm fully depleted silicon on insulator technology dedicated to production of SOI detectors. The chip was irradiated with 60Cobalt gamma-ray source to total dose of 1.175 kGy at a rate of 67.8 Gy/h. During irradiation, current-voltage characteristics of seventeen different transistors were measured so as to investigate factors affecting radiation resistance. Transistors' threshold voltage shift and transconductance change as a function of the deposited dose are presented. After irradiation all transistors manifested correct operation and threshold voltage change of around 200 mV fall within the limits of specified technological mismatch.
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Electron Pattern Recognition using trigger mode SOI pixel sensor for Advanced Compton Imaging
Shimazoe K., Yoshihara Y., Fairuz A., Koyama A., Takahashi H., Takeda A., Tsuru T., Arai Y.
Journal of Instrumentation 11 ( 2 ) 2016年2月
記述言語:日本語 掲載種別:研究論文(学術雑誌) 出版者・発行元:Journal of Instrumentation
© 2016 IOP Publishing Ltd and Sissa Medialab srl. Compton imaging is a useful method for localizing sub MeV to a few MeV gamma-rays and widely used for environmental and medical applications. The direction of recoiled electrons in Compton scattering process provides the additional information to limit the Compton cones and increases the sensitivity in the system. The capability of recoiled electron tracking using trigger-mode Silicon-On-Insulator (SOI) sensor is investigated with various radiation sources. The trigger-mode SOI sensor consists of 144 by 144 active pixels with 30 μm cells and the thickness of sensor is 500 μm. The sensor generates the digital output when it is hit by gamma-rays and 25 by 25 pixel pattern of surrounding the triggered pixel is readout to extract the recoiled electron track. The electron track is successfully observed for 60Co and 137Cs sources, which provides useful information for future electron tracking Compton camera.
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Improving charge-collection efficiency of SOI pixel sensors for X-ray astronomy
Matsumura H., Tsuru T., Tanaka T., Takeda A., Arai Y., Mori K., Nishioka Y., Takenaka R., Kohmura T., Nakashima S., Hatsui T., Kohmura Y., Takei D., Kameshima T.
Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment 794 255 - 259 2015年7月
記述言語:日本語 掲載種別:研究論文(学術雑誌) 出版者・発行元:Nuclear Instruments and Methods in Physics Research, Section A: Accelerators, Spectrometers, Detectors and Associated Equipment
© 2015 Elsevier B.V. Abstract We have been developing a new type of active pixel sensor, referred to as "XRPIX" for future X-ray astronomy satellites on the basis of silicon-on-insulator CMOS technology. The problem on our previous device, XRPIX1b, was degradation of the charge-collection efficiency (CCE) at pixel borders. In order to investigate the non-uniformity of the CCE within a pixel, we measured sub-pixel response with X-ray beams whose diameters are 10μmΦ at SPring-8. We found that the X-ray detection efficiency and CCE degrade in the sensor region under the pixel circuitry placed outside the buried p-wells (BPW). A 2D simulation of the electric fields with the semiconductor device simulator HyDeLEOS shows that the isolated pixel circuitry outside the BPW makes local minimums in the electric potentials at the interface between the sensor and buried oxide layers, where a part of charge is trapped and is not collected to the BPW. Based on this result, we modified the placement of the in-pixel circuitry in the next device, XRPIX2b, for the electric fields to be converged toward the BPW, and confirmed that the CCE at pixel borders is successfully improved.
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Takeda A., Tsuru T., Tanaka T., Uchida H., Matsumura H., Arai Y., Mori K., Nishioka Y., Takenaka R., Kohmura T., Nakashima S., Kawahito S., Kagawa K., Yasutomi K., Kamehama H., Shrestha S.
Journal of Instrumentation 10 ( 6 ) 2015年6月
記述言語:日本語 掲載種別:研究論文(学術雑誌) 出版者・発行元:Journal of Instrumentation
© 2015 IOP Publishing Ltd and Sissa Medialab srl. We have been developing monolithic active pixel sensors series, named ''XRPIX'', based on the silicon-on-insulator (SOI) pixel technology, for future X-ray astronomical satellites. The XRPIX series offers high coincidence time resolution (∼ 1 μs), superior readout time (∼ 10 μs), and a wide energy range (0.5-40 keV) . In the previous study, we successfully demonstrated X-ray detection by event-driven readout of XRPIX2b. We here report recent improvements in spectroscopic performance. We successfully increased the gain and reduced the readout noise in XRPIX2b by decreasing the parasitic capacitance of the sense-node originated in the buried p-well (BPW) . On the other hand, we found significant tail structures in the spectral response due to the loss of the charge collection efficiency when a small BPW is employed. Thus, we increased the gain in XRPIX3b by introducing in-pixel charge sensitive amplifiers instead of having even smaller BPW . We finally achieved the readout noise of 35 e<sup>-</sup> (rms) and the energy resolution of 320 eV (FWHM) at 6 keV without significant loss of the charge collection efficiency.
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Characterization of high resolution CMOS monolithic active pixel detector in SOI technology
Ahmed M., Arai Y., Glab S., Idzik M., Kapusta P., Miyoshi T., Takeda A., Turala M.
Journal of Instrumentation 10 ( 5 ) 2015年5月
記述言語:日本語 掲載種別:研究論文(学術雑誌) 出版者・発行元:Journal of Instrumentation
© 2015 IOP Publishing Ltd and Sissa Medialab srl. Novel CMOS monolithic pixel detectors designed at KEK and fabricated at Lapis Semiconductor in 0.2 μm Silicon-on-Insulator (SOI) technology are presented. A thin layer of silicon oxide separates high and low resistivity silicon layers, allowing for optimization of design of detector and readout parts. Shallow wells buried under the oxide in the detector part screen the entire pixel electronics from electrical field applied to the detector. Several integration type SOI pixel detectors have been developed with pixel sizes 8-20 μm. The general features of 14 × 14 μm2 detectors designed on different wafers (CZ-n, FZ-n and FZ-p) were measured and compared. The detector performance was studied under irradiation with visible and infra-red laser, and also X-ray ionizing source. Using X-rays from an Am-241 source the noise of readout electronics was measured at different working conditions, showing the ENC in the range of 88-120 e-. The pixel current was calculated from average DC pedestal shift while varying the pixel integration time. The operation of the detector was studied under partial and full depletion conditions. The effects of temperature and detector bias voltage on noise and leakage current were studied. Characteristics of an ADC integrated in the front-end chip are also presented.