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Kajimoto, Tsuyoshi*; Shigyo, Nobuhiro*; Sanami, Toshiya*; Iwamoto, Yosuke; Hagiwara, Masayuki*; Lee, H. S.*; Soha, A.*; Ramberg, E.*; Coleman, R.*; Jensen, D.*; et al.
Nuclear Instruments and Methods in Physics Research B, 337, p.68 - 77, 2014/10
Times Cited Count：5 Percentile：37.93(Instruments & Instrumentation)The energy spectra of neutrons were measured by a time-of-flight method for 120 GeV protons on thick graphite, aluminum, copper, and tungsten targets with an NE213 scintillator at the Fermilab Test Beam Facility. Neutron energy spectra were obtained between 25 and 3000 MeV at emission angles of 30, 45, 120, and 150
. The spectra were parameterized as neutron emissions from three moving sources and then compared with theoretical spectra calculated by PHITS and FLUKA codes. The yields of the theoretical spectra were substantially underestimated compared with the yields of measured spectra. The integrated neutron yields from 25 to 3000 MeV calculated with PHITS code were 16-36% of the experimental yields and those calculated with FLUKA code were 26-57% of the experimental yields for all targets and emission angles.
and 90 bombarded with 120-GeV protonsIwamoto, Yosuke; Sanami, Toshiya*; Kajimoto, Tsuyoshi*; Shigyo, Nobuhiro*; Hagiwara, Masayuki*; Lee, H. S.*; Soha, A.*; Ramberg, E.*; Coleman, R.*; Jensen, D.*; et al.
Progress in Nuclear Science and Technology (Internet), 3, p.65 - 68, 2012/10
Neutron energy spectra at 15 and 90 produced from carbon, aluminum, copper and tungsten targets bombarded with 120-GeV protons were measured at Fermilab Test Beam Facility (FTBF) for the validation of simulation codes. The target thicknesses were 60 cm for graphite, 50 cm for aluminum, 20, 40, and 60 cm for copper and 10 cm for tungsten, respectively. The neutron time-of-flight measurements were performed using an NE213 organic liquid scintillator at 5.2 m for 90 and 8.0 m for 15 measuring from the center of the target to the surface of the detector. The raw signals (waveforms) obtained from photomultiplier tubes were recorded using the 10 bit digitizer (Agilent-acqiris DC282) with 0.5 ns sampling and 500 ns duration. To compare the experimental results, Monte Carlo calculations with the PHITS, MARS and FLUKA codes were performed. It was found that these calculated results underestimate the experimental results in the whole energy range.
Fukuda, Tatsuo; Baron, A. Q. R.*; Nakamura, Hiroki; Shamoto, Shinichi; Ishikado, Motoyuki; Machida, Masahiko; Uchiyama, Hiroshi*; Iyo, Akira*; Kito, Hijiri*; Mizuki, Junichiro; et al.
Physical Review B, 84(6), p.064504_1 - 064504_13, 2011/08
Times Cited Count：9 Percentile：39.24(Materials Science, Multidisciplinary)
; Comparison with LaFePONishi, Ichiro*; Ishikado, Motoyuki; Ideta, Shinichiro*; Malaeb, W.*; Yoshida, Teppei*; Fujimori, Atsushi*; Kotani, Yoshinori*; Kubota, Masato*; Ono, Kanta*; Yi, M.*; et al.
Physical Review B, 84(1), p.014504_1 - 014504_5, 2011/07
Times Cited Count：22 Percentile：65.59(Materials Science, Multidisciplinary)We have performed an angle-resolved photoemission spectroscopy (ARPES) study of the iron-based superconductor PrFeAsO and examined the Fermi surfaces and band dispersions near the fermi level. Heavily hole-doped electronic states have been observed due to the polar nature of the cleaved surfaces. Nevertheless, we have found that the ARPES spectra basically agree with band dispersions calculated in the local density approximation (LDA) if the bandwidth is reduced by a factor of 
2.5 and then the chemical potential is lowered by 70 meV. Comparison with previous ARPES results on LaFePO reveals that the energy positions of the 
- and 
-derived bands are considerably different between the two materials, which we attribute to the different pnictogen height as predicted by the LDA calculation.
collisions at 
= 200 GeVAdare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Y.*; Al-Bataineh, H.*; Alexander, J.*; Aoki, K.*; Aphecetche, L.*; Armendariz, R.*; et al.
Physical Review D, 84(1), p.012006_1 - 012006_18, 2011/07
Times Cited Count：29 Percentile：73.24(Astronomy & Astrophysics)We report on the event structure and double helicity asymmetry (
) of jet production in longitudinally polarized collisions at = 200 GeV. Photons and charged particles were measured by the PHENIX experiment. Event structure was compared with the results from PYTHIA event generator. The production rate of reconstructed jets is satisfactorily reproduced with the next-to-leading-order perturbative QCD calculation. We measured = -0.0014 
0.0037 at the lowest 
bin and -0.0181 0.0282 at the highest bin. The measured is compared with the predictions that assume various 
distributions.
collisions at = 200 and 62.4 GeVAdare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Armendariz, R.*; et al.
Physical Review C, 83(6), p.064903_1 - 064903_29, 2011/06
Times Cited Count：184 Percentile：99.45(Physics, Nuclear)Transverse momentum distributions and yields for 
, and 
in collisions at = 200 and 62.4 GeV at midrapidity are measured by the PHENIX experiment at the RHIC. We present the inverse slope parameter, mean transverse momentum, and yield per unit rapidity at each energy, and compare them to other measurements at different collisions. We also present the scaling properties such as 
and 
scaling and discuss the mechanism of the particle production in collisions. The measured spectra are compared to next-to-leading order perturbative QCD calculations.
and Au+Au collisions at 
= 200 GeVAdare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Yasuyuki*; Al-Bataineh, H.*; Alexander, J.*; Aoki, Kazuya*; Aphecetche, L.*; Aramaki, Y.*; et al.
Physical Review C, 83(4), p.044912_1 - 044912_16, 2011/04
Times Cited Count：9 Percentile：49.6(Physics, Nuclear)Measurements of electrons from the decay of open-heavy-flavor mesons have shown that the yields are suppressed in Au+Au collisions compared to expectations from binary-scaled collisions. Here we extend these studies to two particle correlations where one particle is an electron from the decay of a heavy flavor meson and the other is a charged hadron from either the decay of the heavy meson or from jet fragmentation. These measurements provide more detailed information about the interaction between heavy quarks and the quark-gluon matter. We find the away-side-jet shape and yield to be modified in Au+Au collisions compared to collisions.
+ collisions at = 200 GeV and scaling properties of hadron productionAdare, A.*; Afanasiev, S.*; Aidala, C.*; Ajitanand, N. N.*; Akiba, Y.*; Al-Bataineh, H.*; Alexander, J.*; Aoki, K.*; Aphecetche, L.*; Armendariz, R.*; et al.
Physical Review D, 83(5), p.052004_1 - 052004_26, 2011/03
Times Cited Count：177 Percentile：98.48(Astronomy & Astrophysics)The PHENIX experiment at RHIC has measured the invariant differential cross section for production of 
, 
, 
and 
mesons in collisions at = 200 GeV. The spectral shapes of all hadron transverse momentum distributions are well described by a Tsallis distribution functional form with only two parameters, 
and 
, determining the high 
and characterizing the low regions for the spectra, respectively. The integrated invariant cross sections calculated from the fitted distributions are found to be consistent with existing measurements and with statistical model predictions.
via inelastic X-ray scatteringFukuda, Tatsuo; Baron, A. Q. R.*; Nakamura, Hiroki; Shamoto, Shinichi; Ishikado, Motoyuki; Machida, Masahiko; Uchiyama, Hiroshi*; Iyo, Akira*; Kito, Hijiri*; Mizuki, Junichiro; et al.
Journal of the Physical Society of Japan, 80(Suppl.B), p.SB015_1 - SB015_4, 2011/01
Times Cited Count：1 Percentile：11.3(Physics, Multidisciplinary)We have investigated phonons of PrFeAsO using high-resolution inelastic X-ray scattering and 
calculations. Extensive measurements show that there are some changes in phonon spectra with temperature and/or doping. However, we compare our data with several calculations and find that the experimentally observed changes are much smaller than differences between the experiment. data and the calculations. Agreement is improved if magnetism is included in the calculations. However, still in disagreement even in the parent sample below T
. We consider several modifications of the calculations. The best agreement is obtained from modifying the nonmagnetic calculation. by softening only the in-plane nearest-neighbor Fe-As force constant. Fluctuating magnetism may be a partial explanation for the failure of the calculations, but seems incomplete in the face of the similarity of the measured phonon response in all the systems investigated including those known to have static magnetism.
Ishikado, Motoyuki; Kajimoto, Ryoichi; Shamoto, Shinichi; Arai, Masatoshi; Iyo, Akira*; Miyazawa, Kiichi*; Shirage, P. M.*; Kito, Hijiri*; Eisaki, Hiroshi*; Kim, S.-W.*; et al.
Journal of the Physical Society of Japan, 78(4), p.043705_1 - 043705_4, 2009/04
Times Cited Count：34 Percentile：80.47(Physics, Multidisciplinary)
F
and PrFeAsO via inelastic X-ray scattering and first-principles calculationFukuda, Tatsuo; Baron, A. Q. R.*; Shamoto, Shinichi; Ishikado, Motoyuki; Nakamura, Hiroki; Machida, Masahiko; Uchiyama, Hiroshi*; Tsutsui, Satoshi*; Iyo, Akira*; Kito, Hijiri*; et al.
Journal of the Physical Society of Japan, 77(10), p.103715_1 - 103715_4, 2008/10
Times Cited Count：42 Percentile：83.16(Physics, Multidisciplinary)The lattice dynamics of LaFeAsOF (
=0, 0.1) and PrFeAsO (
0.1) are investigated using inelastic X-ray scattering. Measurements of powder samples provide an approximation to the phonon DOS, while dispersion is measured from a single crystal of PrFeAsO. A model that agrees reasonably well with all of the data at room temperature is built from results of ab-initio calculations by reducing the strength of the Fe-As bond by 30%.
Yoshida, Hidekazu; Metcalfe, R.*; Yamamoto, Koshi*; Amano, Yuki; Hoshii, Daisuke*; Kanekiyo, Akiko*; Naganuma, Takeshi*; Hayashi, Toru*
Applied Geochemistry, 23(8), p.2364 - 2381, 2008/08
Times Cited Count：9 Percentile：26.07(Geochemistry & Geophysics)Subsurface redox fronts control the mobilization and fixation of many trace elements. Any safety assessment for a deep geological repository for radioactive wastes needs to take into account adequately the long-term redox processes in the geosphere surrounding the repository. The water-rock-microbe interactions can be considered analogous to the processes occurring in the redox fronts that would develop around geological repositories for radioactive waste. Once formed, the Fe-ooxyhydroxides within such a front would be preserved even after reducing conditions resume following repository closure.
Watanabe, Takehito*; Arakawa, Hiroyuki*; Kajimoto, Tsuyoshi*; Iwamoto, Yosuke; Satoh, Daiki; Kunieda, Satoshi; Noda, Shusaku*; Shigyo, Nobuhiro*; Ishibashi, Kenji*; Nakamura, Takashi*; et al.
Nuclear Instruments and Methods in Physics Research A, 587(1), p.20 - 28, 2008/03
Times Cited Count：1 Percentile：13.72(Instruments & Instrumentation)We have developed a phoswich detector for neutron spectrometry, which adopts a reversed configuration of slow- and fast-decay-time scintillators in its inner and surrounding outer regions, respectively, in the detection of recoil protons from a hydrogenous radiator. The phoswich detector consists of an inner slow, NaI(Tl) scintillator, and an outer fast, plastic scintillator. The response functions of the phoswich detector were measured for neutron energies ranging from 100 to 350 MeV. The experiment used the recoil-proton method and pulse-shape discrimination with the two-gate integration technique using a spallation neutron source at the WNR facility of the LANSCE. To evaluate the effectiveness of the phoswich configuration, full energy deposition fraction was calculated. The calculation confirmed that the phoswich detector with a reversed configuration is useful for neutron measurements.
Takenaga, Hidenobu; Oyama, Naoyuki; Urano, Hajime; Kamiya, Kensaku; Miyo, Yasuhiko; Nishiyama, Tomokazu; Sasajima, Tadayuki; Masaki, Kei; Hiratsuka, Hajime; Ichige, Hisashi; et al.
Europhysics Conference Abstracts (CD-ROM), 30I, 4 Pages, 2006/00
no abstracts in English
F and PrFeAsO via inelastic X-ray scatteringFukuda, Tatsuo; Baron, A. Q. R.*; Shamoto, Shinichi; Ishikado, Motoyuki; Nakamura, Hiroki; Machida, Masahiko; Uchiyama, Hiroshi*; Tsutsui, Satoshi*; Iyo, Akira*; Kito, Hijiri*; et al.
no journal, ,
We studied the lattice dynamics of powders, LaFeAsOF (=0, 0.1) and PrFeAsO (0.4), and a single crystal, PrFeAsO (0.1), using inelastic X-ray scattering. The third peak in phonon density of states are found to be softened by 5 meV compared with ab-initio calculations. A model that agrees reasonably well with all of the data is built from results of ab-initio calculations by reducing the strength of the Fe-As bond by 30%.
Ishikado, Motoyuki; Kajimoto, Ryoichi; Shamoto, Shinichi; Arai, Masatoshi; Iyo, Akira*; Miyazawa, Kiichi*; Shirage, P. M.*; Kito, Hijiri*; Eisaki, Hiroshi*; Kim, S.*; et al.
no journal, ,
no abstracts in English
Ishikado, Motoyuki; Kajimoto, Ryoichi; Shamoto, Shinichi; Arai, Masatoshi; Iyo, Akira*; Miyazawa, Kiichi*; Shirage, P. M.*; Kito, Hijiri*; Eisaki, Hiroshi*; Kim, S.-W.*; et al.
no journal, ,
no abstracts in English
Ishikado, Motoyuki; Kajimoto, Ryoichi; Shamoto, Shinichi; Arai, Masatoshi; Iyo, Akira*; Miyazawa, Kiichi*; Shirage, P. M.*; Kito, Hijiri*; Eisaki, Hiroshi*; Kim, S.-W.*; et al.
no journal, ,
The parent compound of Fe oxypnictide superconductor, LaFeAsO, has been studied by pulsed neutron powder inelastic scattering measurement. The inelastic scattering intensity along Q-axis at T = 140 K exhibits a prominent asymmetric peak ascribed to (
, , 
) magnetic rod, suggesting the two-dimensionality of the spin density wave.
Ishikado, Motoyuki; Kajimoto, Ryoichi; Shamoto, Shinichi; Arai, Masatoshi; Iyo, Akira*; Miyazawa, Kiichi*; Shirage, P. M.*; Kito, Hijiri*; Eisaki, Hiroshi*; Kim, S.-W.*; et al.
no journal, ,
The parent compound of Fe oxypnictide superconductor, LaFeAsO, has been studied by pulsed neutron powder inelastic scattering measurement. The inelastic scattering intensity along Q-axis at T=140 K exhibits prominent asymmetric peaks ascribed to the magnetic rod, suggesting the two-dimensionality of the spin density wave above the magnetic transition temperature. It persists even in the tetragonal phase up to room temperature.
Fukuda, Tatsuo; Baron, A. Q. R.*; Shamoto, Shinichi; Uchiyama, Hiroshi*; Ishikado, Motoyuki; Nakamura, Hiroki; Machida, Masahiko; Mizuki, Junichiro; Arai, Masatoshi; Iyo, Akira*; et al.
no journal, ,
Recently discovered iron-arsenide new superconductor has attracted considerable attraction. Within a few months the transition temperature (
) exceeded 50 K in some related compounds, and the possible novel physics as well as higher- are expected. At the early stage, calculations of phonon properties appeared and suggested that the superconductivity in these materials are not phonon mediated. However, the experimental verification is crucial. We carried out inelastic X-ray scattering on some powder as well as single samples, and found pronounced softening of the Fe-As modes compared to LDA-based phonon calculations. However, further investigation on single crystals showed the spectra are found to agree much better with calculations of the magnetic parent material, which has orthorhombic symmetry, than those using a tetragonal structure like the real superconducting compounds.
