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Journal Articles

Fast neutron detection under intense $$gamma$$-ray fields with novel nuclear emulsion technique

Ishihara, Kohei*; Takagi, Keisuke*; Minato, Haruna*; Kawarabayashi, Jun*; Tomita, Hideki*; Maeda, Shigetaka; Naka, Tatsuhiro*; Morishima, Kunihiro*; Nakano, Toshiyuki*; Nakamura, Mitsuhiro*; et al.

Radiation Measurements, 55, p.79 - 82, 2013/08

https://doi.org/10.1016/j.radmeas.2012.10.019
 Times Cited Count：1 Percentile：10.69(Nuclear Science & Technology)

In order to measure the neutron under a condition of high intensity of $$gamma$$-ray background, we made new nuclear emulsion based on non-sensitized OPERA emulsion which had small AgBr grain size (AgBr grain size of 60, 90 and 160 nm). The sensitivity of this new emulsion, which was a correlation between stopping power and grain density, was estimated experimentally by irradiating neutrons with several energies. We also simulated the response to $$gamma$$-ray induced electrons and compared with some experimental results by using $$^{60}$$Co $$gamma$$ source. The results showed that there might be a threshold energy deposited in one AgBr grain under which it was impossible to develop. We estimated efficiency to the $$gamma$$-ray and the neutron with this obtained response of the new emulsion.

Journal Articles

Development of neutron measurement in intense $$gamma$$ field using new type of nuclear emulsion

Kawarabayashi, Jun*; Ishihara, Kohei*; Takagi, Keisuke*; Tomita, Hideki*; Iguchi, Tetsuo*; Naka, Tatsuhiro*; Morishima, Kunihiro*; Maeda, Shigetaka

Journal of ASTM International (Internet), 9(3), 5 Pages, 2012/03

https://doi.org/10.1520/JAI104007

In order to measure the neutron from a spent fuel assembly in fast breeder reactor precisely, we made new nuclear emulsion based on non-sensitized OPERA film with AgBr grain size of 60, 90 and 160 nm. The efficiency for $$^{252}$$Cf neutron of the new emulsion was calculated to be 0.7$$times$$10$$^{-4}$$ which energy ranged from 0.3 to 2 MeV that agrees with preliminary estimated value from experimental results. The sensitivity of the new emulsion was also estimated experimentally by irradiating 565 KeV and 14 MeV neutrons and found that the emulsion with the AgBr grain size of 60 nm showed the lowest sensitivity among these three emulsions but still had enough sensitivity for proton. Also, there was a suggestion from the experimental data that there was a threshold LET of 15 KeV/$$mu$$m for our new emulsion below which no silver cluster was developed. Further development of the response of nuclear emulsion with a few tens of nano-meter AgBr size is next step of this study.

Oral presentation

Sensitivity control of nuclear emulsion using AgBr nano-grains

Ishihara, Kohei*; Takagi, Keisuke*; Kawarabayashi, Jun*; Tomita, Hideki*; Naka, Tatsuhiro*; Asada, Takashi*; Morishima, Kunihiro*; Nakamura, Mitsuhiro*; Kuge, Kenichi*; Maeda, Shigetaka; et al.

no journal, , 

The nuclear emulsion with AgBr nano-grains has been developed for neutron detection under high $$gamma$$-ray background. It has been demonstrated that the detection sensitivity of $$gamma$$-rays can be well suppressed compared to that of neutrons by adjusting the size of AgBr nano-grains to deposit the energy of the secondary electrons produced by $$gamma$$-rays below a certain threshold which can create Ag latent images.

Oral presentation

Development of neutron spectrum measurement in high $$gamma$$ field using new nuclear emulsion, 1; Overview

Kawarabayashi, Jun*; Maeda, Shigetaka; Takagi, Keisuke*; Ishihara, Kohei*; Tomita, Hideki*; Morishima, Kunihiro*; Iguchi, Tetsuo*

no journal, , 

The nuclear plate has an advantage which is a feeling of an owner as outstanding spatial resolution or a multi-radiation species, though measurement is simple at power supply needlessness. By controlling the diameter of AgBr crystalline particles in a film plate by this research, the film plate composition to which $$gamma$$ ray sensitivity was reduced was tried, and it developed aiming at the neutron precision measurement under the high $$gamma$$ ray background represented on the spent-nuclear-fuel surface etc.

Oral presentation

Development of neutron spectrum measurement in high $$gamma$$ field using new nuclear emulsion, 2; Recognition algorithm for recoiled proton track based on three dimensional analysis of the novel nuclear emulsion

Takagi, Keisuke*; Ishihara, Kohei*; Tomita, Hideki*; Kawarabayashi, Jun*; Iguchi, Tetsuo*; Morishima, Kunihiro*; Maeda, Shigetaka; Matsumoto, Tetsuro*

no journal, , 

In the novel nuclear emulsion development to measurement a neutron spectrum in high $$gamma$$-ray field, in order to control $$gamma$$-ray sensitivity, the ArBr grains of about 100 nm of particle diameter is used. The recoil proton track induced by neutron is recorded on nuclear emulsion. The track constituted by a silver grains child standing in a row discretely is recorded. The track extraction algorithm suitable for extraction of recoil proton was developed, and the characteristic was evaluated.

Oral presentation

Temperature dependence of $$gamma$$-ray and neutron sensitivities of nuclear emulsion with AgBr nano-grains

Ishihara, Kohei*; Kawarabayashi, Jun*; Tomita, Hideki*; Naka, Tatsuhiro*; Asada, Takashi*; Morishima, Kunihiro*; Nakamura, Mitsuhiro*; Maeda, Shigetaka; Iguchi, Tetsuo*

no journal, , 

In order to establish a neutron spectrum measurement in high $$gamma$$ field such as spent nuclear fuel storage, advanced nuclear emulsion based on non-sensitized OPERA film with AgBr grain size of 60 nm has been developed. A nuclear emulsion has the feature of being easy to cause latent image degradation in the high temperature condition. In this study, the experiment estimated the temperature dependency of the sensitivity to the $$gamma$$ ray and neutron of a new nuclear emulsion. It is confirmed that the detection efficiency for a neutron and $$gamma$$ fell in more than 30 $$^{circ}$$C environment.

Oral presentation

Investigation of development condition with novel nuclear emulsion for neutron measurement under high $$gamma$$-ray background

Ishihara, Kohei*; Sakai, Yosuke*; Kawarabayashi, Jun*; Tomita, Hideki*; Naka, Ryuta*; Asada, Takashi*; Morishima, Kunihiro*; Nakamura, Mitsuhiro*; Maeda, Shigetaka; Iguchi, Tetsuo*

no journal, , 

In order to measure neutron spectrum in high $$gamma$$-ray field, a new nuclear emulsion and its data-processing system are developed. This report examined the optimal development conditions about the new nuclear emulsion NGITA (Neutron-Gamma Image TrAcker). By lowering developing solution temperature to 10 $$^{circ}$$C from 20 $$^{circ}$$C, the sensitivity to a $$gamma$$ ray was able to be controlled to the abbreviation 1/10, with the sensitivity to a neutron maintained.

Oral presentation

Development of automatic readout and recognition of nuclear emulsion for fast neutron measurement

Sakai, Yosuke*; Minato, Haruna*; Ishihara, Kohei*; Tomita, Hideki*; Kawarabayashi, Jun*; Iguchi, Tetsuo*; Naka, Tatsuhiro*; Asada, Takashi*; Morishima, Kunihiro*; Nakano, Toshiyuki*; et al.

no journal, , 

In order to measure a neutron-spectrum under high $$gamma$$ ray environment, a new nuclear emulsion and its data-processing method are developed. In fast neutron measurement using the nuclear emulsion which can record the three-dimensional track of a charged particle, incidence neutron energy spectrum can be obtained by analyzing the track of the recoil proton generated by the elastic scattering of a neutron. The high-speed automatic analytic method of the recoil proton track in a nuclear plate is developed. It checked that the recoil proton track length distribution obtained by viewing and automatic analysis was in agreement with a model calculation result about by the basic experiment using 14 MeV neutron.

Oral presentation

Development of automatic readout and recognition of recoiled proton track in nuclear emulsion for fast neutron measurement

Sakai, Yosuke*; Minato, Haruna*; Ishihara, Kohei*; Tomita, Hideki*; Kawarabayashi, Jun*; Iguchi, Tetsuo*; Naka, Tatsuhiro*; Asada, Takashi*; Morishima, Kunihiro*; Nakano, Toshiyuki*; et al.

no journal, , 

In order to measure a neutron-spectrum under high $$gamma$$ ray environment, a new nuclear emulsion and its data-processing method are developed. In fast neutron measurement using the nuclear emulsion which can record the three-dimensional track of a charged particle, incidence neutron energy spectrum can be obtained by analyzing the track of the recoil proton generated by the elastic scattering of a neutron. The high-speed automatic analytic method of the recoil proton track in a nuclear plate is developed. It checked that the recoil proton track length distribution obtained by viewing and automatic analysis was in agreement with a model calculation result about by the basic experiment using 14 MeV neutron.

Oral presentation

Acceleration of background gas ions due to Coulomb explosion of clusters triggered by irradiation of ultrashort, intense laser pulses

Kanasaki, Masato; Jinno, Satoshi*; Sakaki, Hironao; Faenov, A. Ya.*; Pikuz, T. A.*; Nishiuchi, Mamiko; Kiriyama, Hiromitsu; Kando, Masaki; Kondo, Kiminori; Matsui, Ryutaro; et al.

no journal, , 

In the laser-driven ion acceleration using cluster-gas target, the acceleration mechanism consists of different processes such as, (a) acceleration of ions due to Coulomb explosion of individual clusters, (b) compression and acceleration of background gas ions due to the Coulomb explosion of clusters, (c) magnetic vortex generation and associated pinching near the rear surface, and (d) sheath acceleration at the interface between the medium and vacuum. To reveal the synergetic interplay between the processes (a) and (b), we have conducted ion acceleration experiments using CO$$_{2}$$ clusters embedded in background H$$_{2}$$ gas with the J-KAREN laser. By a careful analysis of CR-39, we have found that the maximum energies of protons and carbon ions are 1.5 MeV and 1.1 MeV/u, respectively. Based on the experimental results, the acceleration mechanism of background gas ions induced by Coulomb explosion of clusters can be discussed with the help from numerical simulations.

Oral presentation

Experimental and theoretical studies on acceleration of background gas ions induced by Coulomb explosion of clusters

Fukuda, Yuji; Kanasaki, Masato; Jinno, Satoshi*; Sakaki, Hironao; Nishiuchi, Mamiko; Faenov, A.*; Pikuz, T.*; Kiriyama, Hiromitsu; Kando, Masaki; Kondo, Kiminori; et al.

no journal, , 

In this study, to understand the synergetic interplay between the Coulomb explosion of clusters and the background gas dynamics, we have conducted ion acceleration experiments using CO$$_2$$ clusters embedded in background H$$_2$$ gas with the J-KAREN laser at JAEA-KPSI. As a result, energy spectra for protons (from background gas) and carbon/oxygen ions (from clusters) are obtained separately for the first time. We found that the maximum energies of protons and carbon/oxygen ions are $$sim$$1.5 MeV and $$sim$$1.1 MeV/u, respectively. Based on the experimental results, the acceleration mechanism of background gas ions induced by Coulomb explosion of clusters is discussed with the help from numerical simulations which employ a particle-in-cell (PIC) method including relaxation and ionization processes of plasma particles (EPIC3D).

Oral presentation

Acceleration of background gas ions induced by Coulomb explosion of clusters

Fukuda, Yuji; Kanasaki, Masato; Jinno, Satoshi*; Sakaki, Hironao; Nishiuchi, Mamiko; Faenov, A.*; Pikuz, T.*; Kiriyama, Hiromitsu; Kando, Masaki; Kondo, Kiminori; et al.

no journal, , 

In the laser-driven ion acceleration using cluster-gas target, the acceleration mechanism consists of different processes such as, (a) acceleration of ions due to Coulomb explosion of individual clusters, (b) compression and acceleration of background gas ions due to the Coulomb explosion of clusters, (c) magnetic vortex generation and associated pinching near the rear surface, and (d) sheath acceleration at the interface between the medium and vacuum. To understand the synergetic interplay between the Coulomb explosion of clusters and the background gas dynamics, we have conducted ion acceleration experiments using CO$$_2$$ clusters embedded in background H$$_2$$ gas with the J-KAREN laser at JAEA-KPSI. By a careful analysis of CR-39, energy spectra for protons (from background gas) and carbon/oxygen ions (from clusters) are obtained separately for the first time. We found that the maximum energies of protons and carbon/oxygen ions are $$sim$$1.5 MeV and $$sim$$1.1 MeV/u, respectively. Based on the experimental results, the acceleration mechanism of background gas ions induced by Coulomb explosion of clusters is discussed with the help from numerical simulations which employ a particle-in-cell (PIC) method including relaxation and ionization processes of plasma particles (EPIC3D).

Oral presentation

Acceleration of background gas ions induced by Coulomb explosion of clusters

Kanasaki, Masato; Jinno, Satoshi*; Sakaki, Hironao; Faenov, A.*; Pikuz, T. A.*; Nishiuchi, Mamiko; Kiriyama, Hiromitsu; Kando, Masaki; Kondo, Kiminori; Matsui, Ryutaro; et al.

no journal, , 

In the previous laser-driven ion acceleration experiment using cluster-gas target, we have only focused on the high energy ions with energies of multi-tens of MeV. In order to reveal synergetic interplay between the Coulomb explosion of clusters and the background gas ions, we have measured protons (background gas ions) separately from carbon and oxygen ions (clusters) by using magnetic spectrometer with CR-39 track detectors. We have found that the number of carbon and oxygen ions decrease sharply at 1 MeV/n. On the other hand, the protons show the Maxwell-Boltzmann energy distribution. Based on the experimental results, the acceleration mechanism of background gas ions induced by Coulomb explosion of clusters can be discussed with the help from numerical simulations.

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