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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:6 Percentile:39.8(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:1 Percentile:86.11(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

High order harmonics from relativistic electron spikes

Pirozhkov, A. S.; Kando, Masaki; Esirkepov, T. Z.; Faenov, A. Y.*; Pikuz, T. A.*; Kawachi, Tetsuya; Sagisaka, Akito; Koga, J. K.; Mori, Michiaki; Kawase, Keigo*; et al.

RAL-TR-2015-025, P. 22, 2015/00

Journal Articles

High order harmonics from relativistic electron spikes

Pirozhkov, A. S.; Kando, Masaki; Esirkepov, T. Z.; Gallegos, P.*; Ahmed, H.*; Ragozin, E. N.*; Faenov, A. Ya.*; Pikuz, T. A.*; Kawachi, Tetsuya; Sagisaka, Akito; et al.

New Journal of Physics (Internet), 16(9), p.093003_1 - 093003_30, 2014/09

 Times Cited Count:22 Percentile:20.08(Physics, Multidisciplinary)

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

High power laser developments with femtosecond to nanosecond pulse durations for laser shock science and engineering

Kiriyama, Hiromitsu; Mori, Michiaki; Suzuki, Masayuki*; Daito, Izuru*; Okada, Hajime; Ochi, Yoshihiro; Tanaka, Momoko; Sato, Masatoshi*; Tamaoki, Yoshinori*; Yoshii, Takehiro*; et al.

Reza Kenkyu, 42(6), p.441 - 447, 2014/06

We describe three specific high power laser systems that are being developed in our laboratory for many applications in high field science, nonlinear optics and material processing. We report on a femtosecond petawatt-class Ti:sapphire chirped-pulse amplification laser system that can produce a pulse energy of 20 J of 40 fs pulse duration, a picosecond high intensity Yb:YAG chirped-pulse amplification laser system that can generate a pulse energy of 100 mJ of 0.5 ps pulse duration, and a nanosecond high repetition rate Nd:YAG laser system that can provide an average power of 360 W with a pulse duration of 30 ns delivered at a 1 kHz repetition rate. We discuss the basic design aspects and present the results from our experimental investigations of these laser systems.

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:52.9(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:66.96(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

Ultra-intense, high spatio-temporal quality petawatt-class laser system and applications

Kiriyama, Hiromitsu; Shimomura, Takuya; Mori, Michiaki; Nakai, Yoshiki*; Tanoue, Manabu; Kondo, Shuji; Kanazawa, Shuhei; Pirozhkov, A. S.; Esirkepov, T. Z.; Hayashi, Yukio; et al.

Applied Sciences (Internet), 3(1), p.214 - 250, 2013/03

 Times Cited Count:13 Percentile:43.11(Chemistry, Multidisciplinary)

This paper reviews techniques for improving the temporal contrast and spatial beam quality in an ultra-intense laser system that is based on chirped-pulse amplification (CPA). We describe the design, performance, and characterization of our laser system, which has the potential for achieving a peak power of 600 TW. We also describe applications of the laser system in the relativistically dominant regime of laser-matter interactions and discuss a compact, high efficiency diode-pumped laser system.

Journal Articles

Stability improvement of a laser-accelerated electron beam and the pulse width measurement of the electron beam

Kotaki, Hideyuki; Mori, Michiaki; Hayashi, Yukio; Kando, Masaki; Daito, Izuru; Fukuda, Yuji; Pirozhkov, A. S.; Koga, J. K.; Bulanov, S. V.

Problems of Atomic Science and Technology, (82), p.134 - 138, 2012/12

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 intensity, high temporal contrast, high repetition-rate laser for laser driven particle acceleration

Suzuki, Masayuki; Kiriyama, Hiromitsu; Daito, Izuru; Okada, Hajime; Ochi, Yoshihiro; Sato, Masatoshi*; Yoshii, Takehiro*; Tamaoki, Yoshinori*; Maeda, Junya*; Matsuoka, Shinichi*; et al.

AIP Conference Proceedings 1465, p.53 - 57, 2012/07

 Times Cited Count:0 Percentile:100

We have reported hundred mJ level, femtosecond pulse duration with the high temporal contrast in an OPCPA/Yb:YAG ceramic thin disk laser system at 10 Hz repetition rate. At an input laser pulse energy of 3.8 mJ from the OPCPA preamplifer the output energy of 130 mJ with spectral bandwidth of 2.5 nm has been obtained from multipass Yb:YAG ceramic thin disk amplifier, and the optical efficiency from LD energy to amplified laser pulse is 9.6%. The recompressed laser pulse duration was measured to be 450 fs. Because the compressor efficiency exceeds 73% the compressed pulse energy can potentially be as high as 95 mJ. The contrast level of this laser pulse was measured to be less than 7.2$$times$$10$$^{-9}$$ at -150 ps. This novel laser system after further amplification using additional amplifiers can be useful for the laser-driven proton acceleration in future.

Journal Articles

Relativistic high harmonic generation in gas jet targets

Pirozhkov, A. S.; Kando, Masaki; Esirkepov, T. Z.; Gallegos, P.*; Ahmed, H.*; Ragozin, E. N.*; Faenov, A. Ya.*; Pikuz, T.; Kawachi, Tetsuya; Sagisaka, Akito; et al.

AIP Conference Proceedings 1465, p.167 - 171, 2012/07

 Times Cited Count:1 Percentile:48.59

Journal Articles

High-order harmonics from bow wave caustics driven by a high-intensity laser

Esirkepov, T. Z.; Pirozhkov, A. S.; Kando, Masaki; Gallegos, P.*; Ahmed, H.*; Ragozin, E. N.*; Faenov, A.*; Pikuz, T.; Kawachi, Tetsuya; Sagisaka, Akito; et al.

AIP Conference Proceedings 1465, p.172 - 180, 2012/07

 Times Cited Count:0 Percentile:100

The bow wave induced mechanism of high-order harmonics generation was discovered using simulations and catastrophe theory. This mechanism feasibility was successfully demonstrated in 3D and 2D PIC simulations. The mechanism and the simulations explained high-order harmonics in the XUV spectral region seen in recent experiments with terawatt lasers. Development of new XUV light and X-ray source based on the high-order harmonics generation mechanism is proposed.

Journal Articles

X-ray emission from relativistically moving electron density cusps

Kando, Masaki; Pirozhkov, A. S.; Nakamura, Tatsufumi; Hayashi, Yukio; Kotaki, Hideyuki; Kawase, Keigo*; Esirkepov, T. Z.; Fukuda, Yuji; Kiriyama, Hiromitsu; Okada, Hajime; et al.

AIP Conference Proceedings 1465, p.159 - 166, 2012/07

 Times Cited Count:0 Percentile:100

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

Soft-X-ray harmonic comb from relativistic electron spikes

Pirozhkov, A. S.; Kando, Masaki; Esirkepov, T. Z.; Gallegos, P.*; Ahmed, H.*; Ragozin, E. N.*; Faenov, A. Ya.*; Pikuz, T.; Kawachi, Tetsuya; Sagisaka, Akito; et al.

Physical Review Letters, 108(13), p.135004_1 - 135004_5, 2012/03

 Times Cited Count:59 Percentile:8.18(Physics, Multidisciplinary)

We demonstrate a new high-order harmonic generation mechanism reaching the "water window" spectral region in experiments with multi-terawatt femtosecond lasers irradiating gas jets. A few hundred harmonic orders are resolved, giving $$mu$$J/sr pulses. Harmonics are collectively emitted by an oscillating electron spike formed at the joint of the boundaries of a cavity and bow wave created by a relativistically self-focusing laser in underdense plasma. The spike sharpness and stability are explained by catastrophe theory. The mechanism is corroborated by particle-in-cell simulations.

Journal Articles

Development of a compact high-spatiotemporal-quality Yb:YAG thin-disk laser system using an optical parametric preamplifier

Kiriyama, Hiromitsu; Suzuki, Masayuki*; Daito, Izuru; Okada, Hajime; Ochi, Yoshihiro; Sato, Masatoshi*; Tamaoki, Yoshinori*; Yoshii, Takehiro*; Maeda, Junya*; Matsuoka, Shinichi*; et al.

Reza Kenkyu, 40(2), p.143 - 145, 2012/02

We demonstrate a compact, high-spatiotemporal-quality, high-intensity diode-pumped Yb:YAG thin-disk chirped-pulse amplification (CPA) laser system that incorporates a nonlinear preamplifier based on optical parametric chirped-pulse amplification (OPCPA). The stretched pulses are amplified in the OPCPA preamplifier and the following Yb:YAG main amplifier to $$sim$$100 mJ at 10 Hz. The broadband amplified beam quality of 1.1 (horizontal direction) and 1.4 (vertical direction) times diffraction limited and pulse compression down to 470 fs with contrast of better than 10$$^{-8}$$ have been achieved successfully.

Journal Articles

Hundred mJ, sub-picoseconds, high temporal contrast OPCPA/Yb:YAG ceramic thin disk hybrid laser system

Suzuki, Masayuki*; Kiriyama, Hiromitsu; Daito, Izuru; Ochi, Yoshihiro; Okada, Hajime; Sato, Masatoshi*; Tamaoki, Yoshinori*; Yoshii, Takehiro*; Maeda, Junya*; Matsuoka, Shinichi*; et al.

Applied Physics B, 105(2), p.181 - 184, 2011/11

 Times Cited Count:4 Percentile:72.71(Optics)

We have demonstrated an OPCPA/Yb:YAG ceramic thin disk hybrid laser system having hundred mJ level pulse energy sub-picosecond pulse duration with high temporal contrast. At an input energy of 3.8 mJ from an OPCPA preamplifier an output energy of 130 mJ was obtained from Yb:YAG ceramic thin disk amplifier. A recompressed pulse duration of 450 fs with a contrast level of less than 7.2$$times$$10$$^-9$$ was obtained. The contrast level is the highest value achieved in Yb:YAG chirped pulse amplification (CPA) laser system with hundred mJ level.

175 (Records 1-20 displayed on this page)