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Journal Articles

How different is the core of $$^{25}$$F from $$^{24}$$O$$_{g.s.}$$ ?

Tang, T. L.*; Uesaka, Tomohiro*; Kawase, Shoichiro; Beaumel, D.*; Dozono, Masanori*; Fujii, Toshihiko*; Fukuda, Naoki*; Fukunaga, Taku*; Galindo-Uribarri. A.*; Hwang, S. H.*; et al.

Physical Review Letters, 124(21), p.212502_1 - 212502_6, 2020/05

 Times Cited Count:9 Percentile:88.96(Physics, Multidisciplinary)

The structure of a neutron-rich $$^{25}$$F nucleus is investigated by a quasifree ($$p,2p$$) knockout reaction. The sum of spectroscopic factors of $$pi 0d_{5/2}$$ orbital is found to be 1.0 $$pm$$ 0.3. The result shows that the $$^{24}$$O core of $$^{25}$$F nucleus significantly differs from a free $$^{24}$$O nucleus, and the core consists of $$sim$$35% $$^{24}$$O$$_{rm g.s.}$$, and $$sim$$65% excited $$^{24}$$O. The result shows that the $$^{24}$$O core of $$^{25}$$F nucleus significantly differs from a free $$^{24}$$O nucleus. The result may infer that the addition of the $$0d_{5/2}$$ proton considerably changes the neutron structure in $$^{25}$$F from that in $$^{24}$$O, which could be a possible mechanism responsible for the oxygen dripline anomaly.

Journal Articles

High-field phase diagram of the heavy-fermion metal CeIn$$_3$$; Pulsed-field NMR study on single crystals up to 56 T

Tokunaga, Yo; Orlova, A.*; Bruyant, N.*; Aoki, Dai*; Mayaffre, H.*; Kr$"a$mer, S.*; Julien, M.-H.*; Berthier, C.*; Horvati$'c$, M.*; Higa, Nonoka; et al.

Physical Review B, 99(8), p.085142_1 - 085142_5, 2019/02

 Times Cited Count:3 Percentile:33.95(Materials Science, Multidisciplinary)

The heavy-fermion antiferromagnet CeIn$$_3$$ exhibits a field-induced anomaly associated with Fermi surface reconstruction at $$H^*sim$$ 45 T, well below the antiferromagnetic (AFM) critical field that exceeds 60 T. In order to explore the origin of this anomaly, we have measured $$^{115}$$In NMR spectra in pulsed magnetic fields up to 56 T using high-quality single crystals. To within experimental resolution, we do not detect any change in the NMR spectra that could suggest a modification in either the character of the hyperfine field or the electric field gradient at In sites through $$H^*$$. This strongly suggests that the 45 T anomaly cannot be simply ascribed to a field-induced change in the magnetic structure of the AFM state.

Journal Articles

$$^{239}$$Pu nuclear magnetic resonance in the candidate topological insulator PuB$$_4$$

Dioguardi, A. P.*; Yasuoka, Hiroshi*; Thomas, S. M.*; Sakai, Hironori; Cary, S. K.*; Kozimor, S. A.*; Albrecht-Schmitt, T. E.*; Choi, H. C.*; Zhu, J.-X.*; Thompson, J. D.*; et al.

Physical Review B, 99(3), p.035104_1 - 035104_6, 2019/01

 Times Cited Count:2 Percentile:22.92(Materials Science, Multidisciplinary)

We present a detailed nuclear magnetic resonance (NMR) study of $$^{239}$$Pu in bulk and powdered single-crystal plutonium tetraboride (PuB$$_4$$), which has recently been investigated as a potential correlated topological insulator. The $$^{239}$$Pu NMR spectra are consistent with axial symmetry of the shift tensor showing for the first time that $$^{239}$$Pu NMR can be observed in an anisotropic environment and up to room temperature. The temperature dependence of the $$^{239}$$Pu shift, combined with a relatively long spin-lattice relaxation time ($$T_1$$), indicate that PuB$$_4$$ adopts a nonmagnetic state with gaplike behavior consistent with our density functional theory calculations. The temperature dependencies of the NMR Knight shift and $$T^{-1}$$ imply bulk gaplike behavior confirming that PuB$$_4$$ is a good candidate topological insulator.

Journal Articles

Activities of the safety and operation project for the international research and development of the sodium-cooled fast reactor in the Generation IV international forum

Sakai, Takaaki; Ren, L.*; Tsige-Tamirat, H.*; Vasile, A.*; Kang, S.-H.*; Ashurko, Y.*; Fanning, T.*

Proceedings of 24th International Conference on Nuclear Engineering (ICONE-24) (DVD-ROM), 7 Pages, 2016/06

Journal Articles

Interplay between quantum fluctuations and reentrant superconductivity with a highly enhanced upper critical field in URhGe

Tokunaga, Yo; Aoki, Dai*; Mayaffre, H.*; Kr$"a$mer, S.*; Julien, M.-H.*; Berthier, C.*; Horvati$'c$, M.*; Sakai, Hironori; Hattori, Taisuke; Kambe, Shinsaku; et al.

Physical Review B, 93(20), p.201112_1 - 201112_5, 2016/05

 Times Cited Count:12 Percentile:59.65(Materials Science, Multidisciplinary)

The ferromagnetic superconductor URhGe has been known to exhibit an extremely large enhancement of the upper critical field when the field is confined and rotated in the ($$ab$$) crystal plane. Our high-field $$^{59}$$Co NMR measurements on 10% Co-doped URhGe up to 30 T prove that this unconventional behavior of the superconductivity (SC) is associated with a strong anisotropy of field-dependent quantum fluctuations near a tricritical point. These fluctuations are rapidly suppressed by the field component along the $$c$$ axis, while being unaffected by any field component along the $$a$$ axis. The observed close interplay between the SC and quantum fluctuations strongly supports a pairing mechanism mediated by these fluctuations in URhGe.

Journal Articles

On-site background measurements for the J-PARC E56 experiment; A Search for the sterile neutrino at J-PARC MLF

Ajimura, Shuhei*; Bezerra, T. J. C.*; Chauveau, E.*; Enomoto, T.*; Furuta, Hisataka*; Harada, Masahide; Hasegawa, Shoichi; Hiraiwa, T.*; Igarashi, Yoichi*; Iwai, Eito*; et al.

Progress of Theoretical and Experimental Physics (Internet), 2015(6), p.063C01_1 - 063C01_19, 2015/06

 Times Cited Count:3 Percentile:32.69(Physics, Multidisciplinary)

The J-PARC E56 experiment aims to search for sterile neutrinos at the J-PARC Materials and Life Science Experimental Facility (MLF). In order to examine the feasibility of the experiment, we measured the background rates of different detector candidate sites, which are located at the third floor of the MLF, using a detector consisting of plastic scintillators with a fiducial mass of 500 kg. The gammas and neutrons induced by the beam as well as the backgrounds from the cosmic rays were measured, and the results are described in this article.

Journal Articles

Reentrant superconductivity driven by quantum tricritical fluctuations in URhGe; Evidence from $$^{59}$$Co NMR in URh$$_{0.9}$$Co$$_{0.1}$$Ge

Tokunaga, Yo; Aoki, Dai*; Mayaffre, H.*; Kr$"a$mer, S.*; Julien, M.-H.*; Berthier, C.*; Horvati$'c$, M.*; Sakai, Hironori; Kambe, Shinsaku; Araki, Shingo*

Physical Review Letters, 114(21), p.216401_1 - 216401_5, 2015/05

 Times Cited Count:41 Percentile:90.04(Physics, Multidisciplinary)

Our measurements of the $$^{59}$$Co NMR spin-spin relaxation in URh$$_{0.9}$$Co$$_{0.1}$$Ge reveal a divergence of electronic spin fluctuations in the vicinity of the field-induced quantum critical point at $$H_Rapprox13$$ T, around which reentrant superconductivity (RSC) occurs in the ferromagnetic heavy fermion compound URhGe. We show that critical fluctuations develop in the same limited region near the field $$H_R$$ as that where RSC is observed. This strongly suggests these quantum fluctuations as the pairing glue responsible for the RSC. The fluctuations observed are characteristic of a tricritical point.

Journal Articles

Emergent antiferromagnetism out of the "hidden-order" state in URu$$_2$$Si$$_2$$; High magnetic field nuclear magnetic resonance to 40 T

Sakai, Hironori; Urbano, R. R.*; Tokunaga, Yo; Kambe, Shinsaku; Suzuki, Michito; Kuhns, P. L.*; Reyes, A. P.*; Tobash, P. H.*; Ronning, F.*; Bauer, E. D.*; et al.

Physical Review Letters, 112(23), p.236401_1 - 236401_5, 2014/06

 Times Cited Count:7 Percentile:53.57(Physics, Multidisciplinary)

Very high field $$^{29}$$Si-NMR measurements using a fully $$^{29}$$Si-enriched URu$$_2$$Si$$_2$$ single crystal were carried out in order to microscopically investigate the "hidden order" (HO) state and adjacent magnetic phases in the high field limit. At the lowest measured temperature of 0.4 K, a clear anomaly reflecting a Fermi surface instability near 22 T inside the HO state is detected by the $$^{29}$$Si shift, $$^{29}K_c$$. Moreover, a strong enhancement of $$^{29}K_c$$ develops near a critical field $$H_{rm c}simeq 35.6$$ T, and the $$^{29}$$Si-NMR signal disappears suddenly at $$H_{rm c}$$, indicating the total suppression of the HO state. Nevertheless, a weak and shifted $$^{29}$$Si-NMR signal reappears for fields higher than $$H_{rm c}$$ at 4.2 K, providing evidence for a magnetic structure within the magnetic phase caused by the Ising-type anisotropy of the uranium ordered moments.

Journal Articles

NMR/NQR Study of pressure-induced superconductor CePt$$_2$$In$$_7$$

Sakai, Hironori; Tokunaga, Yo; Kambe, Shinsaku; Lee, H.*; Sidorov, V. A.*; Tobash, P. H.*; Ronning, F.*; Bauer, E. D.*; Thompson, J. D.*

Journal of Physics; Conference Series, 391, p.012057_1 - 012057_4, 2012/12

 Times Cited Count:4 Percentile:82.69

Zero-field $$^{115}$$In-nuclear magnetic resonance (NMR) has been used to study single crystals of CePt$$_2$$In$$_7$$, a heavy-fermion antiferromagnet with a N$'e$el temperature ($$T_{rm N}$$) of 5.2 K at ambient pressure. The NMR spectra under zero field near the 3$$nu_{rm Q}$$ line of the orthorhombic In(3) sites are tracked by temperatures down to 1.6 K and by hydrostatic pressures up to 2.4 GPa. These data reveal the coexistence of commensurate (C) and incommensurate (IC) antiferromagneic orders at ambient pressure and that the C-AFM ordering is stabilized by increasing pressures where bulk superconductivity emerges. We will show the recent data of spectra and nuclear relaxation rates ($$1/T_1$$) under pressures.

Journal Articles

$$mu$$SR evidence of nonmagnetic order and $$^{141}$$Pr hyperfine-enhanced nuclear magnetism in the cubic $$Gamma_3$$ ground doublet system PrTi$$_2$$Al$$_{20}$$

Ito, Takashi; Higemoto, Wataru; Ninomiya, Kazuhiko; Luetkens, H.*; Baines, C.*; Sakai, Akito*; Nakatsuji, Satoru*

Journal of the Physical Society of Japan, 80(11), p.113703_1 - 113703_4, 2011/11

 Times Cited Count:27 Percentile:79.19(Physics, Multidisciplinary)

Journal Articles

Magnetic-field-induced enhancement of nuclear spin-lattice relaxation rates in the heavy-fermion superconductor CeCoIn$$_5$$ using $$^{59}$$Co nuclear magnetic resonance

Sakai, Hironori; Brown, S. E.*; Baek, S.-H.*; Ronning, F.*; Bauer, E. D.*; Thompson, J. D.*

Physical Review Letters, 107(13), p.137001_1 - 137001_5, 2011/09

 Times Cited Count:14 Percentile:66.39(Physics, Multidisciplinary)

$$^{59}$$Co nuclear spin lattice relaxation has been measured for the heavy-fermion superconductor CeCoIn$$_5$$ in a range of applied fields directed parallel to the $$c$$-axis. An enhanced normal state relaxation rate, observed at low temperatures and fields just above $$H_{c2}(0)$$, is taken as a direct measure of the dynamical susceptibility and provides microscopic evidence for an antiferromagnetic instability. The results are well-described using the self-consistent renormalized theory for two-dimensional antiferromagnetic spin fluctuations, and parameters obtained in the analysis are applied to previously reported specific heat and thermal expansion data with good agreement.

Journal Articles

Dilute La-substitutions in CeRhIn$$_5$$ studied by means of NMR/NQR techniques

Sakai, Hironori; Kurita, Nobuyuki*; Miclea, C. F.*; Movshovich, R.*; Lee, H.-O.*; Ronning, F.*; Bauer, E. D.*; Thompson, J. D.*

Journal of the Physical Society of Japan, 80(Suppl.A), p.SA059_1 - SA059_3, 2011/07

The effect of dilute La substitution in Ce$$_{1-x}$$La$$_{x}$$RhIn$$_{5}$$ (0$$le$$x$$le$$0.07) has been investigated microscopically by nuclear magnetic/quadrupole resonance (NMR/NQR). By the dilute La substitutions, the 4$$nu_{rm Q}$$ lines for In(1) sites are found to be undisturbed and to have a reasonably narrow width, even in the ordered AF state. These 4$$nu_{rm Q}$$ positions in the La-substituted CeRhIn$$_{5}$$ indicate a decrease of the internal field on In(1) sites, due to the reduction of hyperfine couplings by La substitutions. The spin-lattice relaxation rates ($$1/T_{1}$$) using these 4$$nu_{rm Q}$$ lines at high temperatures can be understood by the reduction of exchange energy and effective moments. On the other hand, $$1/T_{1}$$ in the AF ordered state can be explained by a gapped Fermi surface and spin fluctuations of uncompensated localized Ce moments near the La ions.

Journal Articles

Event structure and double helicity asymmetry in jet production from polarized $$p + p$$ collisions at $$sqrt{s}$$ = 200 GeV

Adare, 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:25 Percentile:72.31(Astronomy & Astrophysics)

We report on the event structure and double helicity asymmetry ($$A_{LL}$$) of jet production in longitudinally polarized $$p + p$$ collisions at $$sqrt{s}$$ = 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 $$A_{LL}$$ = -0.0014 $$pm$$ 0.0037 at the lowest $$P_T$$ bin and -0.0181 $$pm$$ 0.0282 at the highest $$P_T$$ bin. The measured $$A_{LL}$$ is compared with the predictions that assume various $$Delta G(x)$$ distributions.

Journal Articles

Identified charged hadron production in $$p + p$$ collisions at $$sqrt{s}$$ = 200 and 62.4 GeV

Adare, 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:156 Percentile:99.42(Physics, Nuclear)

Transverse momentum distributions and yields for $$pi^{pm}, K^{pm}, p$$, and $$bar{p}$$ in $$p + p$$ collisions at $$sqrt{s}$$ = 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 $$sqrt{s}$$ collisions. We also present the scaling properties such as $$m_T$$ and $$x_T$$ scaling and discuss the mechanism of the particle production in $$p + p$$ collisions. The measured spectra are compared to next-to-leading order perturbative QCD calculations.

Journal Articles

Recharge evaluation of northern area in Hokkaido, Japan

Ikeda, Makoto; Munakata, Masahiro; Sakai, Ryutaro; Kimura, Hideo; Jia, H.*; Matsuba, Hisashi*

Nihon Chikasui Gakkai 2011-Nen Shunki Koenkai Koen Yoshi, p.86 - 91, 2011/05

no abstracts in English

Journal Articles

Stabilization of commensurate antiferromagnetism in CePt$$_2$$In$$_7$$ by pressure up to 2.4 GPa; $$^{115}$$In NMR and NQR under zero field

Sakai, Hironori; Tokunaga, Yo; Kambe, Shinsaku; Lee, H.-O.*; Sidorov, V. A.*; Tobash, P. H.*; Ronning, F.*; Bauer, E. D.*; Thompson, J. D.*

Physical Review B, 83(14), p.140408_1 - 140408_4, 2011/04

 Times Cited Count:20 Percentile:66.65(Materials Science, Multidisciplinary)

Zero-field $$^{115}$$In-nuclear magnetic resonance (NMR) has been used to study single crystals of CePt$$_{2}$$In$$_{7}$$, a heavy-fermion antiferromagnet with a N$'e$el temperature ($$T_{rm N}$$) of 5.2 K at ambient pressure. Narrow linewidths of $$^{115}$$In-nuclear quadrupolar resonance (NQR) spectra are observed from each of three crystallographically inequivalent In(1), In(2) and In(3) sites. The NMR spectra under zero field near the 3$$nu_{rm Q}$$ line of the orthorhombic In(3) sites are tracked by temperatures down to 1.6 K and by hydrostatic pressures up to 2.4 GPa. These data reveal the coexistence of commensurate and incommensurate antiferromagnetic (AFM) orders at ambient pressure and that the commensurate ordering is stabilized by increasing pressures where bulk superconductivity emerges.

Journal Articles

Azimuthal correlations of electrons from heavy-flavor decay with hadrons in $$p+p$$ and Au+Au collisions at $$sqrt{s_{NN}}$$ = 200 GeV

Adare, 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:8 Percentile:52.71(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 $$p+p$$ 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 $$p+p$$ collisions.

Journal Articles

Measurement of neutral mesons in $$p$$ + $$p$$ collisions at $$sqrt{s}$$ = 200 GeV and scaling properties of hadron production

Adare, 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:149 Percentile:98.49(Astronomy & Astrophysics)

The PHENIX experiment at RHIC has measured the invariant differential cross section for production of $$K^0_s$$, $$omega$$, $$eta'$$ and $$phi$$ mesons in $$p + p$$ collisions at $$sqrt{s}$$ = 200 GeV. The spectral shapes of all hadron transverse momentum distributions are well described by a Tsallis distribution functional form with only two parameters, $$n$$ and $$T$$, determining the high $$p_T$$ and characterizing the low $$p_T$$ 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.

Journal Articles

Anisotropic spin fluctuations and superconductivity in "115" heavy fermion compounds; $$^{59}$$Co NMR study in PuCoGa$$_5$$

Baek, S.-H.*; Sakai, Hironori; Bauer, E. D.*; Mitchell, J. N.*; Kennison, J. A.*; Ronning, F.*; Thompson, J. D.*

Physical Review Letters, 105(21), p.217002_1 - 217002_4, 2010/11

 Times Cited Count:12 Percentile:62.18(Physics, Multidisciplinary)

We report results of $$^{59}$$Co nuclear magnetic resonance measurements on a single crystal of superconducting PuCoGa$$_5$$ in its normal state. The nuclear spin-lattice relaxation rates and the Knight shifts as a function of temperature reveal an anisotropy of spin fluctuations with finite wave vector ${it q}$. By comparison with the isostructural members, we conclude that antiferromagnetic ${it XY}$-type anisotropy of spin fluctuations plays an important role in mediating superconductivity in these heavy fermion materials.

Journal Articles

Anisotropy of antiferromagnetic spin fluctuations in the heavy fermion superconductors of Ce${it M}$In$$_5$$ and Pu${it M}$Ga$$_5$$ (${it M}$=Co, Rh)

Sakai, Hironori; Kambe, Shinsaku; Tokunaga, Yo; Haga, Yoshinori; Baek, S.-H.*; Ronning, F.*; Bauer, E. D.*; Thompson, J. D.*

Materials Research Society Symposium Proceedings, Vol.1264, p.69 - 79, 2010/10

The anisotropy of antiferromagnetic spin fluctuations has been investigated microscopically in the heavy fermion systems of Ce${it M}$In$$_5$$ and Pu${it M}$Ga$$_5$$ (${it M}$=Co, Rh) by means of nuclear magnetic resonance (NMR). Both systems are known to be relatively high-$$T_c$$ superconductors among the heavy fermion systems, especially PuCoGa$$_5$$, which has a $$T_c$$=18.5 K almost one order of magnitude larger than for CeCoIn$$_5$$ ($$T_c$$=2.3 K). Analysis of the Knight shift and spin-lattice relaxation rates suggests XY-type anisotropy in the antiferromagnetic spin fluctuations in the normal states of these unconventional superconductors. Moreover, the 115 superconductors with larger XY-type fluctuations have a higher $$T_c$$, compared with the anisotropy of spin fluctuations in the related paramagnetic system UFeGa$$_5$$ and antiferromagnets UPtGa$$_5$$, NpCoGa$$_5$$, NpFeGa$$_5$$.

47 (Records 1-20 displayed on this page)