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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

https://doi.org/10.1103/PhysRevD.84.012006
 Times Cited Count：34 Percentile：75.41(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

https://doi.org/10.1103/PhysRevC.83.064903
 Times Cited Count：199 Percentile：99.34(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

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

https://doi.org/10.1103/PhysRevC.83.044912
 Times Cited Count：10 Percentile：53.54(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

https://doi.org/10.1103/PhysRevD.83.052004
 Times Cited Count：190 Percentile：98.27(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

Influence of self-irradiation on the magnitude of the superfluid density in PuCoGa$$_5$$ probed by muon spin rotation

Oishi, Kazuki; Heffner, R. H.; Ito, Takashi; Higemoto, Wataru; Morris, G. D.*; Bauer, E. D.*; Graf, M. J.*; Zhu, J.-X.*; Morales, L. A.*; Sarrao, J. L.*; et al.

Physica B; Condensed Matter, 403(5-9), p.1013 - 1014, 2008/04

https://doi.org/10.1016/j.physb.2007.10.079
 Times Cited Count：0 Percentile：0.00(Physics, Condensed Matter)

PuCoGa$$_5$$ has attracted much interest because it is the first Pu-based superconductor, having an order of magnitude higher transition temperature $$T_{rm c}=18.5$$K than the isostructural heavy fermion superconductor CeCoIn$$_5$$ ($$T_{rm c}=2.3$$K). The mechanism of the superconductivity in PuCoGa$$_5$$ is still under investigation, though recent experiments and theory suggest a magnetic origin. A unique aspect of this compound is the self-irradiation damage because Pu ($$^{239}$$Pu, $$T^{1/2}$$ = 24,000 years) creates lattice defects which scatter electrons and, hence, break superconducting pairs. In order to elucidate the magnitude and temperature dependence of the magnetic penetration depth $$lambda$$, we have performed $$mu$$SR measurements in the same PuCoGa$$_5$$ single crystals after 25 and 400 days of aging. We found that $$T_{rm c}$$ decreased from 18.5K to 15K for the aged sample, yet a quasi-linear temperature dependence was found for the low-temperature $$lambda(T)$$ in both the fresh and aged sample, consistent with $$d$$-wave pairing symmetry. The magnitude of the muon spin relaxation rate $$sigma$$ in the aged sample, $$sigmapropto 1/lambda^2proptorho_s/m^*$$, where $$rho_s$$ and $$m^*$$ are the superfluid density and the effective mass, respectively, is reduced by about 70% compared to fresh sample. This indicates that the scattering from self-irradiation induced defects is not in the limit of the conventional Abrikosov-Gor'kov pair-breaking theory, but rather in the limit of short coherence length (about 2nm in PuCoGa$$_5$$) superconductivity.

Journal Articles

The Search for magnetic order in $$delta$$-Pu metal using muon spin relaxation

Heffner, R. H.; Oishi, Kazuki; Fluss, M. J.*; Morris, G. D.*; MacLaughlin, D. E.*; Shu, L.*; Chung, B. W.*; McCall, S. K.*; Bauer, E. D.*; Sarrao, J. L.*; et al.

Journal of Alloys and Compounds, 444-445, p.80 - 83, 2007/10

https://doi.org/10.1016/j.jallcom.2006.12.026
 Times Cited Count：9 Percentile：49.21(Chemistry, Physical)

We summarize the results of muon spin relaxation ($$mu$$SR) measurements carried out in$$alpha$$- and $$delta$$-Pu and in the superconducting state ofPuCoGa$$_5$$. In Pu metal, interest has centered on whether or not magnetic order exists in the hightemperature fcc $$delta$$ phase,The Pu metal studies were designed to search for evidence of magnetic ordering, andhave set the most stringent limits to date for the ordered moment. In PuCoGa$$_5$$ the temperature dependence of themagnetic penetration depth $$lambda$$(T) was investigated in a fresh sample and again in the same sampleafter 400 days of aging. We find $$lambda$$(T)$$propto$$ T for T $$<$$ Tc/2, indicating a line of nodes in thesuperconducting order parameter. Remarkably, the temperature dependence of $$lambda$$(T) is littlechanged even after significant radiation damage.

Journal Articles

Muon spin rotation measurements of the superfluid density in fresh and aged superconducting PuCoGa$$_5$$

Oishi, Kazuki; Heffner, R. H.; Morris, G. D.*; Bauer, E. D.*; Graf, M. J.*; Zhu, J.-X.*; Morales, L. A.*; Sarrao, J. L.*; Fluss, M. J.*; MacLaughlin, D. E.*; et al.

Physical Review B, 76(6), p.064504_1 - 064504_10, 2007/08

https://doi.org/10.1103/PhysRevB.76.064504
 Times Cited Count：13 Percentile：49.90(Materials Science, Multidisciplinary)

Journal Articles

Muon spin relaxation and hyperfine-enhanced $$^{141}$$Pr nuclear spin dynamics in Pr(Os,Ru)$$_4$$Sb$$_{12}$$ and (Pr,La)Os$$_4$$Sb$$_{12}$$

Shu, L.*; MacLaughlin, D. E.*; Aoki, Yuji*; Tsunashima, Yoshino*; Yonezawa, Yuki*; Sanada, Shotaro*; Kikuchi, Daisuke*; Sato, Hideyuki*; Heffner, R. H.; Higemoto, Wataru; et al.

Physical Review B, 76(1), p.014527_1 - 014527_8, 2007/07

https://doi.org/10.1103/PhysRevB.76.014527
 Times Cited Count：22 Percentile：64.33(Materials Science, Multidisciplinary)

Journal Articles

Magnetic penetration depth and self-induced irradiation effects in superconducting PuCoGa$$_5$$ probed by muon spin rotation

Oishi, Kazuki; Heffner, R. H.; Morris, G. D.*; Fluss, M. J.*; Bauer, E. D.*; Morales, L. A.*; Sarrao, J. L.*; MacLaughlin, D. E.*; Shu, L.*; Ito, Takashi; et al.

Journal of Magnetism and Magnetic Materials, 310(2, Part1), p.566 - 568, 2007/03

no abstracts in English

Journal Articles

Two-fluid model of heavy fermion formation and $$mu$$SR knight shift measurements in UBe$$_{13}$$

Heffner, R. H.; MacLaughlin, D. E.*; Sonier, J. E.*; Fundley, M. F.*; Thompson, J. D.*

Journal of Magnetism and Magnetic Materials, 310(2, Part1), p.e6 - e8, 2007/03

Recently phenomenological picture of the formation of the heavy femion state was put forward in terms of a two-component susceptibility, one component corresponding to non-interacting local moments and second, low-temperature component associated with onset of heavy fermation state (so-called "two-fluid" model). This phenomenology can be studied by measuring the local susceptibility via $$mu$$SR Knight shift measurements. Normally, the Knight shift is proposional to the bulk susceptibility. The onset of second component appears as a deviation in the linear relation. Previously we discovered a non-linear relation in U$$_{1-x}$$Th$$_{x}$$Be$$_{13}$$, which was interpreted in terms of a temperature-dependent hyperfine field. Here we reexamine these data in terms of the two-fluid model. Our analysis shows that these date are consistent with the scaling law proposed. The $$mu$$SR data are discussed in terms of related changes in the resistivity and the NMR relaxation rates in these systems.

Journal Articles

Time reversal symmetry breaking in superconducting (Pr,La)Os$$_4$$Sb$$_{12}$$ and Pr(Os,Ru)$$_4$$Sb$$_{12}$$

Shu, L.*; Higemoto, Wataru; Aoki, Yuji*; Frederick, N. A.*; Yuhasz, W. M.*; Heffner, R. H.; Oishi, Kazuki; Ishida, Kenji*; Kadono, Ryosuke*; Koda, Akihiro*; et al.

Journal of Magnetism and Magnetic Materials, 310(2, Part1), p.551 - 553, 2007/00

https://doi.org/10.1016/j.jmmm.2006.10.528
 Times Cited Count：7 Percentile：33.47(Materials Science, Multidisciplinary)

Journal Articles

$$mu$$SR studies of Pu metal and the Pu-based superconductor PuCoGa$$_5$$

Heffner, R. H.; Bauer, E. D.*; Chung, B.*; Fluss, M. J.*; Higemoto, Wataru; Ito, Takashi; MacLaughlin, D. E.*; Morales, L. A.*; Morris, G. D.*; Oishi, Kazuki; et al.

Journal of the Physical Society of Japan, 75(Suppl.), p.14 - 19, 2006/08

no abstracts in English

Journal Articles

Susceptibility inhomogeneity and non-Fermi liquid behavior in UCu$$_{5-x}$$Pt$$_x$$

MacLaughlin, D. E.*; Rose, M. S.*; Bernal, O. O.*; Heffner, R. H.; Nieuwenhuys, G. J.*; Chau, R.*; Maple, M. B.*

Physica B; Condensed Matter, 374-375, p.174 - 176, 2006/03

https://doi.org/10.1016/j.physb.2005.11.044
 Times Cited Count：0 Percentile：0.00(Physics, Condensed Matter)

Transverse-field $$mu$$SR shifts and relaxation rates have been measured in the non-Fermi liquid alloy system UCu$$_{5-x}$$Pt$$_x$$. At low temperatures the fractional spread in Knight shifts is 2 for x=1, but is only half this value for x=1.5 and 2.5. In a disorder-driven scenario where the NFL behavior is due to a broadly distributed characteristic energy E, our results indicate that $$delta$$E/E$$_{av}sim(delta$$K/K)$$_{Trightarrow 0}$$ is similar for UCu$$_{5-x}$$Pd$$_x$$. Our results correlate with the observed suppression of other NFL anomaliess.

Journal Articles

Critical slowing down in the geometrically frustrated pyrochlore antiferromagnet Gd$$_2$$Ti$$_2$$O$$_7$$

MacLaughlin, D. E.*; Rose, M. S.*; Anderson, J. E.*; Shu, L.*; Heffner, R. H.; Kimura, Tsuyoshi*; Morris, G. D.*; Bernal, O. O.*

Physica B; Condensed Matter, 374-375, p.142 - 144, 2006/03

https://doi.org/10.1016/j.physb.2005.11.036
 Times Cited Count：3 Percentile：16.82(Physics, Condensed Matter)

Longitudinal-field muon spin relaxation experiments have been carried out in the paramagnetic state of single-crystal Gd$$_2$$Ti$$_2$$O$$_7$$ just above the phase transition. At high applied fields the relaxation time is proportional to field. At low fields the relaxation rate increases markedly as the freezing temperature is approached. This behavior is consistent with the very long autocorrelation function cutoff time.

Journal Articles

Effect of annealing on glassy dynamics and non-Fermi liquid behavior in UCu$$_4$$Pd

MacLaughlin, D. E.*; Rose, M. S.*; Anderson, J. E.*; Bernal, O. O.*; Heffner, R. H.; Nieuwenhuys, G. J.*; Baumbach, R. E.*; Butch, N. P.*; Maple, M. B.*

Physica B; Condensed Matter, 374-375, p.177 - 179, 2006/03

https://doi.org/10.1016/j.physb.2005.11.046
 Times Cited Count：1 Percentile：6.03(Physics, Condensed Matter)

Longitudinal-field $$mu$$SR experiments have been performed in unannealed and annealed samples of the heavy-fermion compound UCu$$_4$$Pd to study the effect of disorder on non-Fermi liquid behavior in this material. The observed scaling exponent independent of annealing. Annealed samples exhibited a reduction of the relaxation rate at low temperatures, indicating that annealing shifts fluctuation noise power to higher frequencies. There was no tendency of the inhomogeneous spread in rates to decrease with annealing. The correlation with residual resistivity previously observed for a number of NFL heavy-electron materials is also found in the present work.

Journal Articles

$$mu$$SR studies of the superconducting order parameter in PuCoGa$$_5$$

Morris, G. D.*; Heffner, R. H.; Bauer, E. D.*; Morales, L. A.*; Sarrao, J. L.*; Fluss, M. J.*; MacLaughlin, D. E.*; Shu, L.*; Anderson, J. E.*

Physica B; Condensed Matter, 374-375, p.180 - 183, 2006/03

https://doi.org/10.1016/j.physb.2005.11.047
 Times Cited Count：15 Percentile：54.34(Physics, Condensed Matter)

Journal Articles

New limits on the ordered moments in $$alpha$$-Pu and Ga-stabilized $$delta$$-Pu

Heffner, R. H.; Morris, G. D.*; Fluss, M. J.*; Chung, B.*; MacLaughlin, D. E.*; Shu, L.*; Anderson, J. E.*

Physica B; Condensed Matter, 374-375, p.163 - 166, 2006/03

https://doi.org/10.1016/j.physb.2005.11.042
 Times Cited Count：8 Percentile：36.82(Physics, Condensed Matter)

The $$mu$$SR measurements in pulutonium metals are reported for the first time. The ground-state properties of Pu metal is not understood clearly. We found the upper limits of the ordered moment in $$alpha$$-Pu and $$delta$$-stabilized Pu is $$<10^{-3}mu_B$$ at $$sim$$4K.

Journal Articles

Limits for ordered magnetism in Pu from muon spin rotation spectroscopy

Heffner, R. H.; Morris, G. D.*; Fluss, M. J.*; Chung, B.*; McCall, S.*; MacLaughlin, D. E.*; Shu, L.*; Oishi, Kazuki; Bauer, E. D.*; Sarrao, J. L.*; et al.

Physical Review B, 73(9), p.094453_1 - 094453_5, 2006/03

https://doi.org/10.1103/PhysRevB.73.094453
 Times Cited Count：37 Percentile：78.15(Materials Science, Multidisciplinary)

no abstracts in English

Journal Articles

Penetration depth study in the heavy-fermion superconductor PrOs$$_4$$Sb$$_{12}$$

Shu, L.*; MacLaughlin, D. E.*; Heffner, R. H.; Callaghan, F. D.*; Sonier, J. E.*; Morris, G. D.*; Bernal, O. O.*; Bosse, A.*; Anderson, J. E.*; Yuhasz, W. M.*; et al.

Physica B; Condensed Matter, 374-375, p.247 - 250, 2006/01

https://doi.org/10.1016/j.physb.2005.11.066
 Times Cited Count：6 Percentile：29.76(Physics, Condensed Matter)

Oral presentation

$$mu$$SR measurements on the superconducting penetration depth in aged PuCoGa$$_5$$

Heffner, R. H.; Oishi, Kazuki; Higemoto, Wataru; Ito, Takashi; Morris, G. D.*; Fluss, M. J.*; MacLaughlin, D. E.*; Shu, L.*; Bauer, E. D.*; Sarrao, J. L.*

no journal, , 

The superconductor PuCoGa$$_{5}$$ possesses a relatively high critical temperature (T$$_{c}$$ = 18.5 K), a moderate mass enhancement (Sommerfeld coefficient $$cong $$ 80 mJ/mol-K$$^{2})$$ and exhibits behavior consistent with spin-fluctuation-induced d-wave superconductivity. It is also radioactive, with its dominant radioisotope $$^{239}$$Pu having a half-life of 2.4 $$times$$ 10$$^{4}$$ yrs. We report $$mu $$SR measurements of the temperature and field dependence of the magnetic field penetration depth $$lambda $$(T,H) in a 400 day-old sample of PuCoGa$$_{5}$$ (T$$_{c}$$ = 15 K), and compare these results to data obtained on the same sample approximately one year earlier. In 600 Oe applied field both measurements show a linear low-temperature behavior for $$lambda $$(T) - $$lambda $$(0) = bT for T/T$$_{c} quad <$$ 0.5 with the same coefficient b. The magnitude of $$lambda $$(0) in the aged sample has increased by a factor of about 1.8. The results are discussed in terms of the effects of radiation damage on the postulated d-wave superconducting order parameter.

24 (Records 1-20 displayed on this page)