Refine your search:     
Report No.
 - 
Search Results: Records 1-20 displayed on this page of 475

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Spin and parity determination of the 3.004-MeV level in $$^{27}$$Al; Its low-lying multiplet structure

Shizuma, Toshiyuki*; Omer, M.; Hajima, Ryoichi*; Shimizu, Noritaka*; Utsuno, Yutaka

Physical Review C, 100(1), p.014307_1 - 014307_6, 2019/07

JAEA Reports

Geant4 physics process for elastic scattering of $$gamma$$-rays

Omer, M.; Hajima, Ryoichi*

JAEA-Data/Code 2018-007, 32 Pages, 2018/06

JAEA-Data-Code-2018-007.pdf:2.64MB
JAEA-Data-Code-2018-007-appendix(CD-ROM).zip:22.71MB

Nuclear resonance fluorescence (NRF) is a promising technique for the non-destructive assay (NDA) of nuclear materials. Its powerfulness is apparent in the highly penetrative $$gamma$$-rays emitted in an isotopic fingerprint of the NRF interactions. However; there exist other interactions that may interfere with the NRF and hence, may limit its accuracy. Of these interactions is the elastic scattering of $$gamma$$-rays by atoms which needs further investigation and testing. Japan Atomic Energy Agency started in 2015 to develop a NDA system based on the NRF for nuclear non-proliferation and nuclear security purposes. One of the tasks of the current development is assessing the effect of the elastic scattering of $$gamma$$-rays on NRF measurement. A new simulation code for the elastic scattering of $$gamma$$-rays has recently been developed in the Geant4 environment. The present JAEA-Data/Code report provides a more detailed description of the simulation code as well as an elaborated illustration of the elastic scattering of $$gamma$$-rays and its interaction cross sections. This report facilitates user feedback of the simulation code which is indispensable for reaching a stable and reliable simulation. The current report would contribute to better understanding of the elastic scattering of $$gamma$$-rays. This research was implemented under the subsidiary for nuclear security promotion of MEXT.

Journal Articles

Including Delbr$"u$ck scattering in GEANT4

Omer, M.; Hajima, Ryoichi*

Nuclear Instruments and Methods in Physics Research B, 405, p.43 - 49, 2017/08

 Times Cited Count:1 Percentile:64.68(Instruments & Instrumentation)

Elastic scattering of $$gamma$$-rays by an atom nearly associates all their interactions with matter. Therefore, the planning of experiments, involving measurements of $$gamma$$-rays, using Monte Carlo simulations usually includes the elastic scattering. However, current simulation tools do not provide a complete picture of the elastic scattering. The majority of these tools assume Rayleigh scattering is the primary contributor to the elastic scattering and neglect other elastic scattering processes, such as nuclear Thomson and Delbr$"u$ck scattering. Here, we develop a tabulation-based method to simulate elastic scattering in one of the most common open-source Monte Carlo simulation toolkits, GEANT4. We collectively include three processes, Rayleigh scattering, nuclear Thomson scattering, and Delbr$"u$ck scattering. Our simulation more appropriately uses differential cross sections based on the second-order scattering matrix instead of current data, which is based on the form factor approximation. Moreover, the superposition of these processes is carefully taken into account emphasizing the complex nature of the scattering amplitudes. The simulation covers an energy range of 0.01 MeV$$leq$$ E $$leq$$3 MeV and all elements with the atomic numbers of 1 $$leq$$ Z $$leq$$ 99. In addition, we verified our simulation by comparing the differential cross section measured in earlier experiments to those extracted from the simulations. We find that the simulations are in good agreement with the experimental measurements. Differences between the experiments and the simulations are 21% for uranium, 24% for lead, 3% for tantalum, and 8% for cerium at 2.754 MeV. Coulomb corrections to the Delbr$"u$ck amplitudes may account for the relatively large differences that appear at higher Z values.

Journal Articles

A Proposal of secure non-destructive detection system of nuclear materials in heavily shielded objects and interior investigation system

Seya, Michio; Hajima, Ryoichi*; Kureta, Masatoshi

Proceedings of INMM 58th Annual Meeting (Internet), 10 Pages, 2017/07

Large size freight cargo containers are the most vulnerable items from nuclear security points of view because of their large volume and weight of cargo inside for hiding heavily shielded objects. For strengthening nuclear security, secure detection of NMs in heavily shielded objects, and safe handling (dismantlement) of detected (suspicious) objects, are essential. These require secure detection of NMs, inspection of detailed interior structures of detected objects, rough characterization of NMs (for nuclear bomb or RDD etc.) and confirmation of existence of explosives etc. By using information obtained by these inspections, safe dismantlement of objects is possible. In this paper, we propose a combination of X-ray scanning system with NRF-based NDD system using monochromatic $$gamma$$-ray beam for a secure detection and interior inspections. We also we propose active neutron NDA system using a DT source for interior inspection of NM part.

Journal Articles

Effects of $$gamma$$-ray polarization in NRF-based nondestructive assay of nuclear materials

Omer, M.; Hajima, Ryoichi*; Shizuma, Toshiyuki*; Koizumi, Mitsuo

Proceedings of INMM 58th Annual Meeting (Internet), 7 Pages, 2017/07

Nuclear resonance fluorescence (NRF) is a process in which the electric and/or the magnetic dipole excitations of the nucleus take place. Since these excitations are unique signatures of each nucleus, the NRF provides a practical tool for a non-destructive detection and assay of nuclear materials. Using a polarized $$gamma$$-ray beam, distinguishing the nature of the excitation is straightforward. At a scattering angle of 90$$^{circ}$$, the electric dipole excitations are radiated normal to the polarization plane whereas the magnetic dipole excitations are radiated in the same plane as the incident beam polarization. By contrast, other $$gamma$$-ray interactions with the atom may exhibit different responses regarding the polarization of the incident beam. For example, the elastic scattering is expected to give approximately 60% lower yield in the direction of the incident beam polarization than the other direction. This fact significantly affects the sensitivity of the NRF technique because it is not possible to separate the NRF and the elastic scattering on the basis of the photon energy. We report the results of a photon scattering experiment on $$^{238}$$U using a 100% linearly polarized $$gamma$$-ray beam with an energy of 2.04 MeV. We demonstrate how the elastic scattering responds to the polarization of the incident beam. Accordingly, we are able to resolve the effects of the polarization of incident photon in an NRF measurement.

Journal Articles

Necessity (proposal) of secure detection system of nuclear materials and interior inspection systems of detected / suspicious objects in non-destructive manner for safe dismantling

Seya, Michio; Hajima, Ryoichi*; Kureta, Masatoshi

Dai-37-Kai Kaku Busshitsu Kanri Gakkai Nippon Shibu Nenji Taikai Rombunshu (CD-ROM), 10 Pages, 2017/02

Large size freight cargo containers are the most volunurable items from nuclear security points of view because of their large volume and weight of cargo inside for hiding heavily shielded objects. For strengthning nuclear security, secure detection of NMs in heavily shielded objects, and safe handling (dismatlement) of detected / suspicious objects for taking out of NMs, are essential. These require the following things, (1) Introduction of secure detection system of NMs, (2) Inspection of deteiled and interior structures of detected objects, (3) Rough chracterization of NMs (for nuclear bomb or RDD etc.) / Confirmation of existence of explosives etc.. By using information obtained by interior inspections, safe dismantlement of objects and taking NMs out are possible. In this papaer, we propose a combined system of X-ray scanning system with NRF-based NDD system using monochromatic $$gamma$$-ray beam not only as a secure detection system of NMs but also interior inspection system (covering (1) and (2)). Also we propose active neutron NDA system using a D-T source for interior inspection of NM part (covering (3)).

Journal Articles

Simulation of the elastic scattering contributions to the NRF-based nondestructive assay of nuclear materials

Omer, M.; Hajima, Ryoichi*; Angell, C.*; Shizuma, Toshiyuki*; Hayakawa, Takehito*; Seya, Michio; Koizumi, Mitsuo

Proceedings of INMM 57th Annual Meeting (Internet), 9 Pages, 2016/07

Isotope-specific $$gamma$$-rays emitted in the nuclear resonance fluorescence (NRF) process provide a good technique for a non-destructive detection and assay of nuclear materials. We are developing technologies relevant to $$gamma$$-ray nondestructive detection and assay utilizing NRF. A Monte Carlo code to simulate NRF process is necessary for design and evaluation of NDA systems. We are developing NRFGeant4, a Geant4-based simulation code, for this purpose. In NRF experiments, highly-enriched targets are generally used such that the NRF signals are dominant and easily measured. In contrast, a real situation may involve very small contents of isotopes of interest. This results in a difficulty in measuring NRF signals because of the interference with other interactions, e.g. elastic scattering. For example, a typical nuclear fuel pellet contains about 90% of $$^{238}$$U as a host material and less than 1% of $$^{239}$$Pu as an isotope of interest. When measuring NRF of $$^{239}$$Pu, there would be a huge background coming from the elastic scattering of $$^{238}$$U. Therefore, an estimation of the elastic scattering with the host material is essential for precise determination of isotope of interest. Satisfying estimation of elastic scattering is currently not available except for some calculations. In the present study, we upgrade our simulation code to include the calculation of elastic scattering events.

Journal Articles

Narrow-band GeV photons generated from an X-ray free-electron laser oscillator

Hajima, Ryoichi; Fujiwara, Mamoru

Physical Review Accelerators and Beams (Internet), 19(2), p.020702_1 - 020702_9, 2016/02

 Times Cited Count:5 Percentile:36.63(Physics, Nuclear)

We propose a scheme to generate narrow-bandwidth GeV photons, $$gamma$$-rays, via Compton scattering of hard X-ray photons in an X-ray free-electron laser oscillator. Generated $$gamma$$-rays show a narrow-bandwidth spectrum with a sharp peak, $$sim$$0.1% (FWHM), due to large momentum transfer from electrons to photons. Such $$gamma$$-rays will be a unique probe for studying hadron physics. Features of the $$gamma$$-ray source, flux, spectrum, polarization, tunability and energy resolution are discussed.

Journal Articles

X-ray generation by collision of electron and laser beams

Hajima, Ryoichi; Terunuma, Nobuhiro*

Isotope News, (741), p.16 - 20, 2016/01

no abstracts in English

Journal Articles

Development of a multialkali photocathode preparation system

Nishimori, Nobuyuki; Hajima, Ryoichi; Nagai, Ryoji; Sawamura, Masaru

Proceedings of 56th ICFA Advanced Beam Dynamics Workshop on Energy Recovery Linacs (ERL 2015) (Internet), p.100 - 102, 2015/12

Journal Articles

Development of a 250 kV photogun for high current operation

Nishimori, Nobuyuki; Nagai, Ryoji; Sawamura, Masaru; Hajima, Ryoichi

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.508 - 510, 2015/09

no abstracts in English

Journal Articles

Status and upgrade plan of the cERL gun

Nishimori, Nobuyuki; Nagai, Ryoji; Mori, Michiaki; Hajima, Ryoichi; Yamamoto, Masahiro*; Honda, Yosuke*; Miyajima, Tsukasa*; Uchiyama, Takashi*; Jin, X.*; Obina, Takashi*; et al.

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.511 - 515, 2015/09

no abstracts in English

Journal Articles

Generation and applications of laser Compton scattered $$gamma$$-ray beams

Hajima, Ryoichi; Sawamura, Masaru; Nagai, Ryoji; Nishimori, Nobuyuki; Hayakawa, Takehito; Shizuma, Toshiyuki; Angell, C.

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.79 - 83, 2015/09

Generation of energy-tunable narrow-bandwidth $$gamma$$-rays via Laser Compton Scattering (LCS) is of great interest for scientific studies and applications of MeV photons which interact with nuclei. We are developing technologies relevant to generation of high-brightness LCS $$gamma$$-ray beams. One of the promising applications of such $$gamma$$-rays is the nondestructive detection and assay of nuclides which are necessary for nuclear security and safeguards. We summarize R-and-D status of LCS $$gamma$$-ray sources and overview future applications.

Journal Articles

Demonstration of laser Compton-scattered photon source at the cERL

Nagai, Ryoji; Hajima, Ryoichi; Shizuma, Toshiyuki; Mori, Michiaki; Akagi, Tomoya*; Kosuge, Atsushi*; Honda, Yosuke*; Araki, Sakae*; Terunuma, Nobuhiro*; Urakawa, Junji*

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.1328 - 1330, 2015/09

Accelerator and laser technologies required for laser Compton scattering (LCS) photon source based on an energy-recovery linac (ERL) have been developed at the Compact ERL (cERL) facility. A high-flux, energy tunable, and monochromatic photon source such as the ERL-based LCS photon source is necessary for nondestructive assay of nuclear materials. For the demonstration of the ERL-based LCS photon generation, a laser enhancement cavity was installed at the recirculation loop of the cERL. The electron beam energy, the laser wavelength, and the collision angle are 20 MeV, 1064 nm, and 18 $$^{circ}$$, respectively. The calculated maximum energy of the LCS photons is about 7 keV. A silicon drift detector (SDD) with active area of 17 mm$$^{2}$$ placed 16.6 m from the collision point was used for observation of the LCS photons. As a result of the measurement, the flux on the detector, central energy, and energy width of the LCS photons were obtained as 1200/s, 6.91 keV, and 81 eV, respectively.

Journal Articles

Status of ERL superconducting spoke cavity fabrication

Sawamura, Masaru; Hajima, Ryoichi; Nishimori, Nobuyuki; Nagai, Ryoji; Iwashita, Yoshihisa*; Tongu, Hiromu*; Kubo, Takayuki*; Saeki, Takayuki*

Proceedings of 12th Annual Meeting of Particle Accelerator Society of Japan (Internet), p.583 - 586, 2015/09

no abstracts in English

Journal Articles

Overview of JAEA-ISCN's NDA development programs (for INMM)

Seya, Michio; Koizumi, Mitsuo; Tomikawa, Hirofumi; Naoi, Yosuke; Kureta, Masatoshi; Harada, Hideo; Hajima, Ryoichi; Nakamura, Hironobu

Proceedings of INMM 56th Annual Meeting (Internet), 10 Pages, 2015/07

ISCN of JAEA has conducted (with collaborations with JAEA other centers) the following development programs of advanced NDA technologies since its establishment. (1) Measurement test of the using PNAR-NDA system for Fugen spent fuel assemblies, (2) Basic development of NRF-NDA technologies using LCS $$gamma$$-rays, (3) Development of alternative to $$^{3}$$He neutron detection technology, (4) Development of neutron resonance densitometry. ISCN has just started the following new programs (also with collaborations with JAEA other centers). (5) Demonstration of NRF-non-destructive detection technology for nuclear security using LCS $$gamma$$-rays, (6) Development of active neutron NDA techniques using a pulsed neutron (D-T) source, (7) Feasibility study on monitoring of high active liquid waste in tanks inside cell. This paper presents the results of basic technology development programs already done and introduces above new programs.

Journal Articles

Demonstrating the integral resonance transmission method; Conceptual and experimental studies

Angell, C.; Hayakawa, Takehito; Shizuma, Toshiyuki; Hajima, Ryoichi; Quiter, B. J.*; Ludewigt, B. L.*; Karwowski, H. J.*; Rich, G.*; Silano, J.*

Proceedings of INMM 56th Annual Meeting (Internet), 9 Pages, 2015/07

Journal Articles

Reaction-yield dependence of the ($$gamma$$, $$gamma$$') reaction of $$^{238}$$U on the target thickness

Negm, H.*; Ogaki, Hideaki*; Daito, Izuru*; Hayakawa, Takehito; Zen, H.*; Kii, Toshiteru*; Masuda, Kai*; Hori, Toshitada*; Hajima, Ryoichi; Shizuma, Toshiyuki; et al.

Journal of Nuclear Science and Technology, 52(6), p.811 - 820, 2015/06

 Times Cited Count:1 Percentile:81.41(Nuclear Science & Technology)

The dependence of the nuclear resonance fluorescence (NRF) yield on the target thickness was studied. To this end, an NRF experiment was performed on $$^{238}$$U using a laser Compton back-scattering (LCS) $$gamma$$-ray beam at the High Intensity $$gamma$$-ray Source facility at Duke University.

Journal Articles

Development of superconducting spoke cavities for laser Compton scattered X-ray sources

Hajima, Ryoichi; Sawamura, Masaru; Kubo, Takayuki*; Saeki, Takayuki*; Cenni, E.*; Iwashita, Yoshihisa*; Tongu, Hiromu*

Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.2902 - 2904, 2015/06

A 5-year research program on the development of superconducting spoke cavities for electron accelerators has been funded by MEXT, Japan since 2013. The purpose of our program is establishing design and fabrication processes of superconducting spoke cavity optimized for compact X-ray sources based on laser Compton scattering. The spoke cavity is expected to realize a compact industrial-use X-ray source with a reasonable cost and easy operation. We have chosen a cavity frequency at 325 MHz due to possible operation at 4 K and carried out cavity shape optimization in terms of electromagnetic and mechanical properties. Production of press-forming dies is also in progress. In this paper, we present overview and up-to-date status of the research program.

Journal Articles

Demonstration of high-flux photon generation from an ERL-based laser Compton photon source

Nagai, Ryoji; Hajima, Ryoichi; Mori, Michiaki; Shizuma, Toshiyuki; Akagi, Tomoya*; Araki, Sakae*; Honda, Yosuke*; Kosuge, Atsushi*; Terunuma, Nobuhiro*; Urakawa, Junji*

Proceedings of 6th International Particle Accelerator Conference (IPAC '15) (Internet), p.1607 - 1609, 2015/06

Accelerator and laser technologies required for laser Compton scattering (LCS) photon source based on an energy-recovery linac (ERL) have been developed at the Compact ERL (cERL) facility. A high-flux, energy tunable, and monochromatic photon source such as the ERL-based LCS photon source is necessary for nondestructive assay of nuclear materials. For the demonstration of the ERL-based LCS photon generation, a laser enhancement cavity was installed at the recirculation loop of the cERL. The electron beam energy, the laser wavelength, and the collision angle are 20 MeV, 1064 nm, and 18 deg., respectively. The calculated maximum energy of the LCS photons is about 7 keV. A silicon drift detector (SDD) with active area of 17 mm$$^{2}$$ placed 16.6 m from the collision point was used for observation of the LCS photons. As a result of the measurement, the flux on the detector, central energy, and energy width of the LCS photons were obtained as 1200 /s, 6.91 keV, and 81 eV, respectively.

475 (Records 1-20 displayed on this page)