Nuclear emulsion with excellent long-term stability developed for cosmic-ray imaging

Nishio, Akira; Morishima, Keisuke; Kuwabara, Kei; Yoshida, Tomohiro; Funakubo, Takeshi; Kitagawa, N.; Kuno, Mitsuaki; Manabe, Yuta; Nakamura, Mitsuhiro

doi:10.1016/j.nima.2020.163850

Cited by 11 publications

(7 citation statements)

References 23 publications

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“…Details of the fabrication method for the emulsion plates are shown in Ref. [47]. We prepared emulsion plates with an area of 1 inch x 3 inch for the observation of small specimens and with an area of 150 x 150 mm 2 for 150-mm SiC wafers.…”

Section: Methodsmentioning

confidence: 99%

“…Muography (cosmic-ray muon radiography) is used to visualize the interior density distribution of large-scale structures [39][40][41][42][43][44][45][46]. Recently, Morishima et al discovered a big void in Khufu's Pyramid by observation of cosmic-ray muons using their developed nuclear emulsion plates [46,47]. In the present study, we have developed a high-resolution nuclear emulsion plate for synchrotron XRT and demonstrated the observation of 150-mm SiC wafers by applying the technology used in the fabrication of nuclear emulsion plates for muon radiography.…”

Section: Introductionmentioning

confidence: 99%

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Development of high-resolution nuclear emulsion plates for synchrotron X-ray topography observation of large-size semiconductor wafers

Harada

Nishigaki

Kitagawa

et al. 2022

Preprint

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Characterization of defects in semiconductor wafers is essential for the development and improvement of semiconductor devices, especially power devices. X-ray topography (XRT) using synchrotron radiation is one of the powerful methods used for defect characterization. To achieve detailed characterization of large-size semiconductor wafers by synchrotron XRT, we have developed nuclear emulsion plates achieving high resolution and wide dynamic range. We have shown that higher-resolution XRT images could be obtained using emulsions with smaller iodobromide crystals and demonstrated clear observation of threading edge dislocations in a SiC epitaxial layer having small contrast. Furthermore, we demonstrated XRT image acquisition for almost all of a 150-mm SiC wafer with one plate. Our development will contribute to advances in electronic materials, especially in the field of power electronics, in which defect characterization is important for improving the performance and yield of devices.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Development of high-resolution nuclear emulsion plates for synchrotron X-ray topography observation of large-size semiconductor wafers

Harada

Nishigaki

Kitagawa

et al. 2022

Preprint

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“…2). The nuclear emulsion films were replaced periodically every few months to avoid performance degradation 9 . In this analysis, data from February to October 2019 were used (Methods).…”

Section: Analysis Of Detectors Installed In the Descending Corridor B...mentioning

confidence: 99%

Precise characterization of a corridor-shaped structure in Khufu’s Pyramid by observation of cosmic-ray muons

et al. 2023

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Khufu’s Pyramid is one of the largest archaeological monument all over the world, which still holds many mysteries. In 2016 and 2017, the ScanPyramids team reported on several discoveries of previously unknown voids by cosmic-ray muon radiography that is a non-destructive technique ideal for the investigation of large-scale structures. Among these discoveries, a corridor-shaped structure has been observed behind the so-called Chevron zone on the North face, with a length of at least 5 meters. A dedicated study of this structure was thus necessary to better understand its function in relation with the enigmatic architectural role of this Chevron. Here we report on new measurements of excellent sensitivity obtained with nuclear emulsion films from Nagoya University and gaseous detectors from CEA, revealing a structure of about 9 m length with a transverse section of about 2.0 m by 2.0 m.

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“…Each detector was buried in a hole that was about 40 cm deep to avoid high temperatures due to direct sunlight. This is done because the number of latent image specks decreases, and the number of randomly generated specks increases, under high-temperature conditions (Nishio et al, 2020).…”

Section: Installationmentioning

confidence: 99%

“…Nuclear emulsion is a type of muon detector, and has been used for studies of volcanoes (Tanaka et al, 2007;Nishiyama et al, 2014;Tioukov et al, 2019). The trajectories of high-energy charged particles that pass through an emulsion film are recorded as aligned silver grains with micron-scale resolution (Nakamura et al, 2005;Tioukov et al, 2019;Nishio et al, 2020). The positions and slopes of aligned grains in a developed emulsion film are digitized with an automated emulsion readout system (Kreslo et al, 2008;Morishima and Nakano, 2010;Bozza et al, 2012;Yoshimoto et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

A muographic study of a scoria cone from 11 directions using nuclear emulsion cloud chambers

Miyamoto

Nagahara

Morishima

et al. 2021

Preprint

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Abstract. One of the key challenges for muographic studies is to reveal the detailed 3D density structure of a volcano by increasing the number of observation directions. 3D density imaging by multi-directional muography requires that the individual differences in the performance of the installed muon detectors are small and that the results from each detector can be derived without any bias in the data analysis. Here we describe a pilot muographic study of the Izu–Omuroyama scoria cone in Shizuoka Prefecture, Japan, from 11 directions, using a new nuclear emulsion detector design optimized for quick installation in the field. We describe the details of the data analysis and present a validation of the results. The Izu–Omuroyama scoria cone is an ideal target for the first multi-directional muographic study, given its expected internal density structure and the topography around the cone. We optimized the design of the nuclear emulsion detector for rapid installation at multiple observation sites in the field, and installed these at 11 sites around the volcano. The images in the developed emulsion films were digitized into segmented tracks with a high-speed automated readout system. The muon tracks in each emulsion detector were then reconstructed. After the track selection, including straightness filtering, the detection efficiency of the muons was estimated. Finally, the density distributions in 2D angular space were derived for each observation site by using a muon flux and attenuation models. The observed muon flux was compared with the expected value in the free sky, and is 88 % ± 4 % in the forward direction and 92 % ± 2 % in the backward direction. The density values were validated by comparison with the values obtained from gravity measurements, and are broadly consistent, except for one site. The excess density at this one site may indicate that the density inside the cone is non-axisymmetric, which is consistent with a previous geological study.

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Nuclear emulsion with excellent long-term stability developed for cosmic-ray imaging

Cited by 11 publications

References 23 publications

Development of high-resolution nuclear emulsion plates for synchrotron X-ray topography observation of large-size semiconductor wafers

Development of high-resolution nuclear emulsion plates for synchrotron X-ray topography observation of large-size semiconductor wafers

Precise characterization of a corridor-shaped structure in Khufu’s Pyramid by observation of cosmic-ray muons

A muographic study of a scoria cone from 11 directions using nuclear emulsion cloud chambers

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