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Journal Articles

Low-lying electric and magnetic dipole strengths in $$^{207}$$Pb

Shizuma, Toshiyuki*; Minato, Futoshi; Omer, M.*; Hayakawa, Takehito*; Ogaki, Hideaki*; Miyamoto, Shuji*

Physical Review C, 103(2), p.024309_1 - 024309_8, 2021/02

 Times Cited Count:0 Percentile:0.03(Physics, Nuclear)

Low-lying dipole transitions in $$^{207}$$Pb were measured via nuclear photon scattering using a quasi-monochromatic, linearly polarized photon beam. The electric ($$E1$$) and magnetic ($$M1$$) dipole strengths were extracted for excitation energies up to 6.8 MeV. The present ($$vec{gamma}$$,$$gamma'$$) results, combined with ($$gamma$$,$$n$$) data from the literature, were used to investigate the $$E1$$ and $$M1$$ photoabsorption cross sections near the neutron separation energy by comparison with predictions of the particle-vibration coupling on top of the quasi-particle random phase approximation (PVC+QRPA).

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:7 Percentile:61.99(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

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:3 Percentile:32.14(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

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

Analysis of nuclear resonance fluorescence excitation measured with LaBr$$_{3}$$(Ce) detectors near 2 MeV

Omer, M.*; Negm, H.*; Ogaki, Hideaki*; Daito, Izuru*; Hayakawa, Takehito; Bakr, M.*; Zen, H.*; Hori, Toshitada*; Kii, Toshiteru*; Masuda, Kai*; et al.

Nuclear Instruments and Methods in Physics Research A, 729, p.102 - 107, 2013/11

 Times Cited Count:5 Percentile:43.78(Instruments & Instrumentation)

The performance of LaBr$$_{3}$$ (Ce) to measure nuclear resonance fluorescence (NRF) excitations is discussedin terms of limits of detection and in comparison with high-purity germanium (HPGe)detectors near the 2 MeV region where many NRF excitation levels from special nuclear materials are located. The NRF experiment was performed at the High Intensity Gamma-ray Source (HIGS) facility of Duke University. The incident $$gamma$$-rays, of 2.12 MeV energy, hit a B$$_{4}$$C target to excite the $$^{11}$$B nuclei to the first excitation level. The statistical-sensitive non-linear peak clipping (SNIP) algorithm was implemented to eliminate theback ground and enhance the limits of detection for the spectra measured with LaBr$$_{3}$$ (Ce). Both detection and determination limits were deduced from the experimental data.

Journal Articles

Nuclear resonance fluorescence of $$^{235}$$U measured with high-resolution LaBr$$_3$$(Ce) scintillation detectors

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

Japanese Journal of Applied Physics, 52(10), p.106401_1 - 106401_4, 2013/10

 Times Cited Count:6 Percentile:30.5(Physics, Applied)

A nuclear resonance fluorescence (NRF) experiment was performed on a $$^{235}$$U target with quasi-monochromatic $$gamma$$-rays at the High Intensity Gamma-ray Source (HIGS) facility of Duke University using a 1733 keV resonant energy. A LaBr$$_3$$ (Ce) detector array consisting of eight cylindrical detectors, each with a length of 7.62 cm and a diameter of 3.81 cm, was implemented in this measurement. Moreover, a high-purity germanium (HPGe) detector array consisting of four detectors, each of which has a relative efficiency of 60%, was used as the benchmark for the measurement taken using the LaBr$$_3$$ (Ce) detector array. The integrated cross section of the NRF level, measured with LaBr$$_3$$ (Ce) detectors, showed good agreement with the available data.

Journal Articles

Generation of laser Compton scattered $$gamma$$-rays from a 150-MeV microtron

Hajima, Ryoichi; Hayakawa, Takehito; Shizuma, Toshiyuki; Angell, C.; Daito, Izuru; Kando, Masaki; Ogaki, Hideaki*

Proceedings of 4th International Particle Accelerator Conference (IPAC '13) (Internet), p.3645 - 3647, 2013/05

Journal Articles

Dipole strength distributions in $$^{56}$$Fe

Shizuma, Toshiyuki; Hayakawa, Takehito; Ogaki, Hideaki; Toyokawa, Hiroyuki*; Komatsubara, Tetsuro*; Kikuzawa, Nobuhiro; Inakura, Tsunenori*; Homma, Michio*; Nakada, Hitoshi*

Physical Review C, 87(2), p.024301_1 - 024301_7, 2013/02

 Times Cited Count:14 Percentile:70.65(Physics, Nuclear)

Electro-magnetic dipole transitions in $$^{56}$$Fe were measured in photon scattering experiments with a linearly polarized photon beam. The parity quantum numbers 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. While the summed magnetic dipole ($$M1$$) strength was determined as $$Sigma B(M1)!uparrow=3.52(17)$$ $$mu_N^2$$ at excitation energies between 7 and 10 MeV, the summed electric dipole ($$E1$$) strength below 10 MeV was obtained as $$Sigma B(E1)!uparrow=78.0(15)times10^{-3},e^2{rm fm}^2$$. The observed $$M1$$ strength was compared with shell-model predictions in the $$pf$$-shell using the GXPF1J and KB3G effective interactions. In addition, the $$E1$$ strength was compared with random-phase approximation calculations with the Skyrme interaction.

Journal Articles

High flux laser-Compton scattered $$gamma$$-ray source by SBS pulse compressed laser

Daito, Izuru; Kando, Masaki; Shizuma, Toshiyuki; Hayakawa, Takehito; Angell, C.; Hajima, Ryoichi; Ogaki, Hideaki*

Purazuma, Kaku Yugo Gakkai-Shi, 88(10), p.553 - 554, 2012/10

no abstracts in English

Journal Articles

High flux laser-Compton scattered $$gamma$$-ray source by compressed Nd:YAG laser pulse

Daito, Izuru; Kando, Masaki; Kotaki, Hideyuki; Hayashi, Yukio; Shizuma, Toshiyuki; Hayakawa, Takehito; Hajima, Ryoichi; Ogaki, Hideaki*

Proceedings of 3rd International Particle Accelerator Conference (IPAC '12) (Internet), p.4124 - 4126, 2012/05

A non-destructive detection system of nuclear material hidden in cargo containers is under development in JAEA and Kyoto University. The system is able to detect and identify isotopes of special nuclear material in a container by employing Nuclear Resonance Fluorescence triggered by mono-energetic laser Compton scattered $$gamma$$-ray. One of the most important technologies for such system is generation of $$gamma$$-rays at a flux of 3$$times$$10$$^{5}$$ photon/s. In order to achieve this $$gamma$$-ray flux with a compact system, a pulse compression system for Nd:YAG laser by using stimulated brillouin scattering has been developed. The laser pulse with a duration of 10 ns from a Nd:YAG laser is compressed down to 200 ps. As a feasibility study of the proposed system 400 keV $$gamma$$-ray generation is performed at KPSI by using 150 MeV electron beam from microtron accelerator and compressed Nd:YAG laser. Experimental results of pulse compression and $$gamma$$-ray generation are presented.

Journal Articles

Nondestructive identification of isotopes using nuclear resonance fluorescence

Shizuma, Toshiyuki; Hayakawa, Takehito; Hajima, Ryoichi; Kikuzawa, Nobuhiro; Ogaki, Hideaki; Toyokawa, Hiroyuki*

Review of Scientific Instruments, 83(1), p.015103_1 - 015103_4, 2012/01

 Times Cited Count:7 Percentile:37.82(Instruments & Instrumentation)

Nondestructive identification of heavy isotopes concealed in a thick iron box has been demonstrated by using nuclear resonance fluorescence. A quasi-monochromatic photon beam produced by the collision of laser quanta with high energy electrons was used for resonant excitation of nuclear levels in $$^{206}$$Pb and $$^{208}$$Pb. By measuring the resonant $$gamma$$ rays emitted from $$^{206}$$Pb and $$^{208}$$Pb, each of these isotopes were clearly identified. The ratio of the effective thickness, i.e., concentration distribution, of these isotopes was deduced from the relative intensities of the measured NRF strengths.

Journal Articles

Development of the nondestructive method of explosive materials shielded by metals

Hayakawa, Takehito; Hajima, Ryoichi; Toyokawa, Hiroyuki*; Ogaki, Hideaki*

Kensa Gijutsu, 15(3), p.47 - 50, 2010/03

no abstracts in English

Journal Articles

Nondestructive detection of hidden chemical compounds with laser Compton-scattering $$gamma$$ rays

Hayakawa, Takehito; Ogaki, Hideaki*; Shizuma, Toshiyuki; Hajima, Ryoichi; Kikuzawa, Nobuhiro; Minehara, Eisuke; Kii, Toshiteru*; Toyokawa, Hiroyuki*

Review of Scientific Instruments, 80(4), p.045110_1 - 045110_5, 2009/04

 Times Cited Count:23 Percentile:70.34(Instruments & Instrumentation)

A non-destructive assay method for measuring a shielded chemical compound has been proposed. The chemical compound is measured by using a nuclear resonance fluorescence (NRF) measurement technique with an energy tunable laser Compton scattering (LCS) $$gamma$$-ray source. This method has an advantage that hidden materials can be detected through heavy shields such as iron plates of a thickness of several centimeters. A detection of a chemical compound of melamine, C$$_{3}$$H$$_{6}$$N$$_{6}$$, shielded by 15-mm-thick iron and 4-mm-thick lead plates is demonstrated. The NRF $$gamma$$-rays of $$^{12}$$C and $$^{14}$$N of the melamine are measured by using the LCS $$gamma$$-rays of the energies of up to 5.0 MeV. The observed ratio ($$^{12}$$C/$$^{14}$$N)$$_{exp}$$ = 0.39 $$pm$$ 0.12 is consistent with (C/N)$$_{melamine}$$ = 0.5.

Journal Articles

Nondestructive detection of heavily shielded materials by using nuclear resonance fluorescence with a laser-Compton scattering $$gamma$$-ray source

Kikuzawa, Nobuhiro; Hajima, Ryoichi; Nishimori, Nobuyuki; Minehara, Eisuke; Hayakawa, Takehito; Shizuma, Toshiyuki; Toyokawa, Hiroyuki*; Ogaki, Hideaki*

Applied Physics Express, 2(3), p.036502_1 - 036502_3, 2009/03

 Times Cited Count:51 Percentile:86.82(Physics, Applied)

Journal Articles

Fine structure of the magnetic-dipole-strength distribution in $$^{208}$$Pb

Shizuma, Toshiyuki; Hayakawa, Takehito; Ogaki, Hideaki*; Toyokawa, Hiroyuki*; Komatsubara, Tetsuro*; Kikuzawa, Nobuhiro; Tamii, Atsushi*; Nakada, Hitoshi*

Physical Review C, 78(6), p.061303_1 - 061303_4, 2008/12

 Times Cited Count:72 Percentile:95.59(Physics, Nuclear)

Spin-flip $$M1$$ strength in $$^{208}$$Pb has been measured in photon scattering experiments with a quasi-monochromatic, linearly polarized photon beam. The data resolve an $$M1$$ giant resonance into at least seven, possibly eight, discrete transitions at excitation energies between 7.1 and 7.4 MeV below the neutron separation energy. The measured $$M1$$ strength in this region is found to be larger than the previous report. The experimental results are compared with an estimation of self-consistent random phase approximation using a semi-realistic interaction.

Journal Articles

Demonstration of isotope imaging method by nuclear resonance fluorescence

Kikuzawa, Nobuhiro; Hajima, Ryoichi; Hayakawa, Takehito; Shizuma, Toshiyuki; Toyokawa, Hiroyuki*; Ogaki, Hideaki*; Minehara, Eisuke

Proceedings of 5th Annual Meeting of Particle Accelerator Society of Japan and 33rd Linear Accelerator Meeting in Japan (CD-ROM), p.598 - 600, 2008/00

Laser-Compton-backscattered photons from an energy-recovery linac (ERL) and a high power laser realize a high-efficiency, high-flux and tunable monochromatic $$gamma$$-ray source. A nondestructive assay method by using the monoenegetic $$gamma$$-rays and nuclear resonance fluorescence (NRF) make possible to isotope imaging. The purpose of our work is to demonstrate of the NRF-based isotope imaging system. For this evaluation, we are developing a GEANT4-based Monte Carlo simulation code. In the simulation, we assume metal cubes (4$$times$$4$$times$$4 mm) of U238 and lead are contained in a concrete block of 5 cm thickness. The simulation results indicate that the nondestructive $$gamma$$ spectrometric method can be applicable in the isotope imaging.

Journal Articles

Photodisintegration cross section measurements on $$^{186}$$W, $$^{187}$$Re and $$^{188}$$Os; Implications for the Re-Os cosmochronology

Shizuma, Toshiyuki; Utsunomiya, Hiroaki*; Mohr, P.*; Hayakawa, Takehito; Goko, Shinji*; Makinaga, Ayano*; Akimune, Hidetoshi*; Yamagata, Tamio*; Ota, Masahisa*; Ogaki, Hideaki*; et al.

Physical Review C, 72(2), p.025808_1 - 025808_9, 2005/08

 Times Cited Count:38 Percentile:88.71(Physics, Nuclear)

Cross sections of the $$^{186}$$W, $$^{187}$$Re, $$^{188}$$Os($$gamma,n$$) reactions were measured using quasi-monochromatic photon beams from laser Compton scattering (LCS) with average energies from 7.3 to 10.9 MeV. The results are compared with the predictions of Hauser-Feshbach statistical calculations using four different sets of input parameters. In addition, the inverse neutron capture cross sections were evaluated by constraining the model parameters, especially the $$E1$$ strength function, on the basis of the experimental data. The present experiment helps to further constrain the correction factor $$F_{sigma}$$ for the neutron capture on the 9.75 keV state in $$^{187}$$Os. Implications of $$F_{sigma}$$ to the Re-Os cosmochronology are discussed with a focus on the uncertainty in the estimate of the age of the Galaxy.

Journal Articles

Photoneutron cross section measurements on $$^{186}$$W, $$^{187}$$Re and $$^{188}$$Os for cosmochronology

Shizuma, Toshiyuki; Utsunomiya, Hiroaki*; Goko, Shinji*; Mohr, P.*; Hayakawa, Takehito; Makinaga, Ayano*; Hara, Kaoru*; Ogaki, Hideaki*; Lui, Y.-W.*; Goriely, S.*

Nuclear Physics A, 758, p.561c - 564c, 2005/07

Photodisintegration experiments were carried out for $$^{186}$$W, $$^{187}$$Re, and $$^{188}$$Os using quasi-monochromatic $$gamma$$-ray beams from laser Compton scattering (LCS) at the National Institute of Advanced Industrial Science and Technology. The excitation function of ($$gamma$$,n) cross sections was measured for the three nuclei near neutron thresholds, taking advantage of the intense peaking of the energy-tunable LCS beam in the energy region of astrophysical importance. Neutron capture cross sections for $$^{185}$$W, $$^{186}$$Re, and $$^{187}$$Os are evaluated from the photodisintegration data with the Hauser-Feshbach statistical model. We quantitatively discuss the two corrections factors for the s-process branchings and the neutron capture on the 9.75 keV state.

Journal Articles

$$s$$-process branching at $$^{185}$$W revised

Mohr, P.*; Shizuma, Toshiyuki; Ueda, Hiroyasu*; Goko, Shinji*; Makinaga, Ayano*; Hara, Kaoru*; Hayakawa, Takehito; Lui, Y.-W.*; Ogaki, Hideaki*; Utsunomiya, Hiroaki*

Physical Review C, 69(3), p.032801_1 - 032801_4, 2004/03

 Times Cited Count:31 Percentile:83.47(Physics, Nuclear)

The neutron capture cross section of the unstable s-process branching nucleus $$^{185}$$W has been derived from experimental data of the inverse $$^{186}$$W($$gamma$$,n)$$^{185}$$W photodisintegration taken with monochromatic photon beams from laser Compton scattering. The result of $$sigma = 553 pm 60$$mb at $$kT = 30$$keV leads to a relatively high effective neutron density in the classical s process of $$N_{rm{n}} = 4.7 times 10^8,{rm{cm}}^{-3}$$. A realistic model for the s process in thermally pulsing AGB stars overestimates the abundance of $$^{186}$$Os significantly because of the relatively small neutron capture cross section of $$^{185}$$W.

Journal Articles

Positron annihilation methods by $$gamma$$-rays produced in laser-induced compton-backscattering

Hirade, Tetsuya; Toyokawa, Hiroyuki*; Odaira, Toshiyuki*; Suzuki, Ryoichi*; Ogaki, Hideaki*

Materials Science Forum, 445-446, p.474 - 476, 2004/02

Positron annihilation methods are very unique and strong tools to investigate materials. However, positrons are usually injected from outside of the samples. Therefore the samples should be in a vacuum or radioisotopes should be attached. Recently, Selim et al. applied high-energy g-rays (2MeV) produced by use of 6MeV electron linac to create positrons in thick materials. We have also been trying a similar method. In our case, high-energy $$gamma$$-rays ($$sim$$20MeV) produced in laser-induced Compton-backscattering are applied for positron creation in samples. The $$gamma$$-rays do not spread and penetrate straightly in air. When you place a sample on the path of $$gamma$$-rays, positrons are created in the sample and usual positron annihilation methods can be applied. Moreover, It is not needed to place the samples in vacuum and radioisotopes are not necessary. It means that the measurements of very high temperature materials such as metals near/over melting points will be possible. The detail of this method and some examples of experimental results will be introduced.

47 (Records 1-20 displayed on this page)