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Journal Articles

Electron-tracking Compton camera imaging of technetium-95m

Hatsukawa, Yuichi*; Hayakawa, Takehito*; Tsukada, Kazuaki; Hashimoto, Kazuyuki*; Sato, Tetsuya; Asai, Masato; Toyoshima, Atsushi; Tanimori, Toru*; Sonoda, Shinya*; Kabuki, Shigeto*; et al.

PLOS ONE (Internet), 13(12), p.e0208909_1 - e0208909_12, 2018/12

 Times Cited Count:0 Percentile:100(Multidisciplinary Sciences)

Imaging of $$^{95m}$$Tc radioisotope was conducted using an electron tracking-Compton camera (ETCC). $$^{95m}$$Tc emits 204, 582, and 835 keV $$gamma$$ rays, and was produced in the $$^{95}$$Mo(p,n)$$^{95m}$$Tc reaction with a $$^{95}$$Mo-enriched target. The recycling of the $$^{95}$$Mo-enriched molybdenum trioxide was investigated, and the recycled yield of $$^{95}$$Mo was achieved to be 70% - 90%. The images were obtained with each of the three $$gamma$$ rays. Results showed that the spatial resolution increases with increasing $$gamma$$-ray energy, and suggested that the ETCC with high-energy $$gamma$$-ray emitters such as $$^{95m}$$Tc is useful for the medical imaging of deep tissue and organs in the human body.

Journal Articles

Low-lying dipole strength in $$^{52}$$Cr

Shizuma, Toshiyuki*; Hayakawa, Takehito*; Daito, Izuru*; Ogaki, Hideaki*; Miyamoto, Shuji*; Minato, Futoshi

Physical Review C, 96(4), p.044316_1 - 044316_10, 2017/10

 Times Cited Count:4 Percentile:37.46(Physics, Nuclear)

The low-lying dipole strength in $$^{52}$$Cr was measured in nuclear resonance fluorescence experiments using a quasi-monochromatic, linearly polarized photon beam. The parities of the excited dipole states were determined by the intensity asymmetry of resonantly scattered $$gamma$$-rays with respect to the polarization plane of the incident photon beam. The summed magnetic dipole (M1) strength was determined as $$sum B(M1)uparrow=5.64(34) mu_N^2$$ at excitation energies between 7.5 and 12.1 MeV; the summed electric dipole (E1) strength was obtained as $$sum B(E1)uparrow=73.7(23) times 10^{-3} e^2$$ fm$$^2$$. The observed M1 and E1 strengths were compared via random phase approximation calculations using the Skyrme interaction. The effects of 2 particle-2 hole configuration mixing and tensor force on dipole strength distributions were investigated.

Journal Articles

Measurement of the isomer production ratio for the $$^{112}$$Cd($$n,gamma$$)$$^{113}$$Cd reaction using neutron beams at J-PARC

Hayakawa, Takehito*; Toh, Yosuke; Huang, M.; Shizuma, Toshiyuki*; Kimura, Atsushi; Nakamura, Shoji; Harada, Hideo; Iwamoto, Nobuyuki; Chiba, Satoshi*; Kajino, Toshitaka*

Physical Review C, 94(5), p.055803_1 - 055803_6, 2016/11

 Times Cited Count:2 Percentile:67.8(Physics, Nuclear)

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

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

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:83.34(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

Diffraction of $$gamma$$-rays with energies of 1.17 and 1.33 MeV by a flat Si crystal

Matsuba, Shunya*; Hayakawa, Takehito; Shizuma, Toshiyuki; Nishimori, Nobuyuki; Nagai, Ryoji; Sawamura, Masaru; Angell, C.; Fujiwara, Mamoru; Hajima, Ryoichi

Japanese Journal of Applied Physics, 54(5), p.052203_1 - 052203_5, 2015/05

 Times Cited Count:3 Percentile:76.7(Physics, Applied)

Journal Articles

Demonstration of a transmission nuclear resonance fluorescence measurement for a realistic radioactive waste canister scenario

Angell, C.; Hajima, Ryoichi; Hayakawa, Takehito; Shizuma, Toshiyuki; Karwowski, H.*; Silano, J.*

Nuclear Instruments and Methods in Physics Research B, 347, p.11 - 19, 2015/03

 Times Cited Count:5 Percentile:38.86(Instruments & Instrumentation)

Journal Articles

Status of $$gamma$$-ray nondestructive assay by laser Compton scattered source

Hajima, Ryoichi; Shizuma, Toshiyuki; Nagai, Ryoji; Mori, Michiaki; Hayakawa, Takehito; Angell, C.; Seya, Michio

Kaku Busshitsu Kanri Gakkai (INMM) Nippon Shibu Dai-35-Kai Nenji Taikai Rombunshu (Internet), 7 Pages, 2015/01

no abstracts in English

Journal Articles

Improving the assay of $$^{239}$$Pu in spent and melted fuel using the nuclear resonance fluorescence integral resonance transmission method

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

Nuclear Physics and $$gamma$$-ray sources for Nuclear Security and Nonproliferation, p.133 - 141, 2014/12

Journal Articles

Validating resonance properties using nuclear resonance fluorescence

Angell, C.; Hajima, Ryoichi; Hayakawa, Takehito; Shizuma, Toshiyuki; Karwowski, H.*; Silano, J.*

Physical Review C, 90(5), p.054315_1 - 054315_6, 2014/11

AA2014-0567.pdf:0.3MB

 Times Cited Count:4 Percentile:57.64(Physics, Nuclear)

Journal Articles

Neutron angular distribution in ($$gamma$$, n) reactions with linearly polarized $$gamma$$-ray beam generated by laser Compton scattering

Horikawa, Ken*; Miyamoto, Shuji*; Mochizuki, Takayasu*; Amano, So*; Li, D.*; Imasaki, Kazuo*; Izawa, Yasukazu*; Ogata, Kazuyuki*; Chiba, Satoshi*; Hayakawa, Takehito

Physics Letters B, 737, p.109 - 113, 2014/10

 Times Cited Count:7 Percentile:45.72(Astronomy & Astrophysics)

It was predicted in 1950's, the neutron angular distribution in ($$gamma$$, n) reactions with a 100% linearly polarized $$gamma$$-ray beam should be anisotropic and described by a simple function of a + b sin$$^{2}$$$${theta}$$ at 90$$^{circ}$$ on the beam axis but it has not been experimentally confirmed for middle-heavy nuclides over than half a century. We have verified experimentally this angular distribution on $$^{197}$$Au, $$^{127}$$I, and natural Cu using linearly polarized laser Compton scattering $$gamma$$-rays at NewSUBARU.

Journal Articles

Non-destructive measurements of nuclear materials in nuclear security

Hayakawa, Takehito; Fujiwara, Mamoru*

Nippon Genshiryoku Gakkai-Shi, 56(7), p.448 - 452, 2014/07

It is considered that progress of nuclear security is important in the world. A key technology for nuclear security is non-destructive measurements of hidden nuclear materials and radioactive isotopes in various conditions. For such purpose, we require helps of professional in wide range fields as nuclear physics, accelerator science, laser science, and nuclear fusion science etc. outside of the traditional nuclear engineering.

Journal Articles

Status of laser Compton scattered $$gamma$$-ray source at JAEA 150-MeV microtron

Hajima, Ryoichi; Ferdows, M.; Hayakawa, Takehito; Shizuma, Toshiyuki; Kando, Masaki; Daito, Izuru*; Negm, H.*; Ogaki, Hideaki*

Proceedings of 5th International Particle Accelerator Conference (IPAC '14) (Internet), p.1943 - 1945, 2014/07

Journal Articles

Application of laser Compton scattered $$gamma$$-ray beams to nondestructive detection and assay of nuclear material

Hajima, Ryoichi; Hayakawa, Takehito; Shizuma, Toshiyuki; Angell, C.; Nagai, Ryoji; Nishimori, Nobuyuki; Sawamura, Masaru; Matsuba, Shunya; Kosuge, Atsushi*; Mori, Michiaki; et al.

European Physical Journal; Special Topics, 223(6), p.1229 - 1236, 2014/05

 Times Cited Count:10 Percentile:56.48(Physics, Multidisciplinary)

Journal Articles

Neutrinos in core-collapse supernovae and nucleosynthesis

Kajino, Toshitaka*; Mathews, G. J.*; Hayakawa, Takehito

Journal of Physics G; Nuclear and Particle Physics, 41(4), p.044007_1 - 044007_34, 2014/04

 Times Cited Count:14 Percentile:21.26(Physics, Nuclear)

Neutrino interactions are a key component of the mechanism for supernova explosions. They also play an important role in the associated nucleosynthesis. Nevertheless, a number of issues remain to be resolved. In this review we summarize research by our group and others on some of these issues. Much effort is now invested in understanding the transport of neutrinos from the core and the role of neutrino heated convection in the outer envelopes. In addition to the neutrino transport issues, we review some current topics in neutrino induced nucleosynthesis (the neutrino and p processes). We review some current issues regarding the synthesis of the neutirno-process isotopes $$^{180}$$Ta and $$^{138}$$La and summarize the application of the neutrino -process chronometers, $$^{136,138}$$Ce, $$^{138}$$La, and$$^{92}$$Nb. We also consider other aspects.

Journal Articles

Delbr$"{u}$ck scattering calculation using the LoopTools package

Koga, J. K.; Hayakawa, Takehito

JPS Conference Proceedings (Internet), 1, p.016008_1 - 016008_4, 2014/03

Journal Articles

Statistical uncertainties of nondestructive assay for spent nuclear fuel by using nuclear resonance fluorescence

Shizuma, Toshiyuki; Hayakawa, Takehito; Angell, C.; Hajima, Ryoichi; Minato, Futoshi; Suyama, Kenya; Seya, Michio; Johnson, M.*; McNabb, D.*

Nuclear Instruments and Methods in Physics Research A, 737, p.170 - 175, 2014/02

 Times Cited Count:1 Percentile:86.07(Instruments & Instrumentation)

We estimated statistical uncertainties of a nondestructive assay system using nuclear resonance fluorescence (NRF) for spent nuclear fuel including low-concentrations of actinide nuclei with an intense, mono-energetic photon beam. Background counts from radioactive materials inside the spent fuel were calculated with the ORIGEN2.2-UPJ burn-up computer code. Coherent scattering contribution associated with Rayleigh, nuclear Thomson, and Delbr$"u$ck scattering was also considered. Assuming that the total NRF cross sections are in the range of 3 to 100 eV$$cdot$$b at excitation energies of 2.25, 3.5, and 5 MeV, statistical uncertainties of the NRF measurement were estimated. We concluded that it is possible to assay 1% actinide content in the spent fuel with 2.2 to 3.2% statistical precision during 4000 second measurement time for the total integrated cross section of 30 eV$$cdot$$b at excitation energies of 3.5 to 5 MeV.

Journal Articles

Supernova neutrino nucleosynthesis of the radioactive $$^{92}$$Nb observed in primitive meteorites

Hayakawa, Takehito; Nakamura, Ko*; Kajino, Toshitaka*; Chiba, Satoshi; Iwamoto, Nobuyuki; Cheoun, M. K.*; Mathews, G. J.*

Astrophysical Journal Letters, 779(1), p.L9_1 - L9_5, 2013/12

 Times Cited Count:21 Percentile:34.64(Astronomy & Astrophysics)

Short-lived radioactivities are used as nuclearcosmochronometers for understanding the free decay time from the last nucleosynthesis episode until the time of solar system formation (SSF). $$^{92}$$Nb (half-life of 34.7 Myr) is one of a short-lived isotope existed at SSF. However, there is a controversy in that the inferred initial abundance ratios for $$^{92}$$Nb/$$^{93}$$Nb at the time of SSF cluster around two different values; one is near 10$$^{-3}$$, while the other is near 10$$^{-5}$$. Moreover, the astrophysical mechanism for the synthesis of $$^{92}$$Nb has remained an unsolved problem. Here we argue that conventional nucleosynthesis mechanisms cannot produce $$^{92}$$Nb and propose a new mechanism for the nucleosynthesis of this isotopebased upon neutrino induced reactions occurring during core-collapse supernova explosions.

340 (Records 1-20 displayed on this page)