| 41. |
- Adare, A., et al.
(författare)
-
Spectra and ratios of identified particles in Au plus Au and d plus Au collisions at root s(NN)=200 GeV
- 2013
-
Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 88:2
-
Tidskriftsartikel (refereegranskat)abstract
- The transverse momentum (p(T)) spectra and ratios of identified charged hadrons (pi(+/-), K-+/-, p, (p) over bar) produced in root s(NN) = 200 GeV Au + Au and d + Au collisions are reported in five different centrality classes for each collision species. The measurements of pions and protons are reported up to p(T) = 6 GeV/c (5 GeV/c), and the measurements of kaons are reported up to p(T) = 4 GeV/c (3.5 GeV/c) in Au + Au (d + Au) collisions. In the intermediate p(T) region, between 2 and 5 GeV/c, a significant enhancement of baryon-to-meson ratios compared to those measured in p + p collisions is observed. This enhancement is present in both Au + Au and d + Au collisions and increases as the collisions become more central. We compare a class of peripheral Au + Au collisions with a class of central d + Au collisions which have a comparable number of participating nucleons and binary nucleon-nucleon collisions. The p(T)-dependent particle ratios for these classes display a remarkable similarity, which is then discussed.
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| 42. |
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| 43. |
- Adare, A., et al.
(författare)
-
System-size dependence of open-heavy-flavor production in nucleus-nucleus collisions at root s(NN)=200 GeV
- 2014
-
Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 90:3
-
Tidskriftsartikel (refereegranskat)abstract
- The PHENIX Collaboration at the Relativistic Heavy Ion Collider has measured open-heavy-flavor production in Cu + Cu collisions at v root s(NN) = 200 GeV through the measurement of electrons at midrapidity that originate from semileptonic decays of charm and bottom hadrons. In peripheral Cu + Cu collisions an enhanced production of electrons is observed relative to p + p collisions scaled by the number of binary collisions. In the transverse momentum range from 1 to 5 GeV/c the nuclear modification factor is R-AA similar to 1.4. As the system size increases to more central Cu + Cu collisions, the enhancement gradually disappears and turns into a suppression. For p(T) > 3 GeV/c, the suppression reaches R-AA similar to 0.8 in the most central collisions. The p(T) and centrality dependence of R-AA in Cu + Cu collisions agree quantitatively with R-AA in d + Au and Au + Au collisions, if compared at a similar number of participating nucleons < N-part >.
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| 44. |
- Adare, A., et al.
(författare)
-
Systematic study of azimuthal anisotropy in Cu plus Cu and Au plus Au collisions at root s(NN)=62.4 and 200 GeV
- 2015
-
Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 92:3
-
Tidskriftsartikel (refereegranskat)abstract
- We have studied the dependence of azimuthal anisotropy nu(2) for inclusive and identified charged hadrons in Au + Au and Cu + Cu collisions on collision energy, species, and centrality. The values of nu(2) as a function of transverse momentum pT and centrality in Au + Au collisions at root s(NN) = 200 and 62.4 GeV are the same within uncertainties. However, in Cu + Cu collisions we observe a decrease in nu(2) values as the collision energy is reduced from 200 to 62.4 GeV. The decrease is larger in the more peripheral collisions. By examining both Au + Au and Cu + Cu collisions we find that nu(2) depends both on eccentricity and the number of participants, N-part. We observe that nu(2) divided by eccentricity (epsilon) monotonically increases with N-part and scales as N-part(1/3). The Cu + Cu data at 62.4 GeV falls below the other scaled nu(2) data. For identified hadrons, nu(2) divided by the number of constituent quarks n(q) is independent of hadron species as a function of transverse kinetic energy K E-T = m(T) - m between 0.1 < K E-T / n(q) < 1 GeV. Combining all of the above scaling and normalizations, we observe a near-universal scaling, with the exception of the Cu + Cu data at 62.4 GeV, of nu(2)/(nq center dot e center dot N-part(1/3)) vs K E-T / n(q) for all measured particles.
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| 45. |
- Adare, A., et al.
(författare)
-
Systematic study of charged-pion and kaon femtoscopy in Au plus Au collisions at root s(NN)=200 GeV
- 2015
-
Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 92:3
-
Tidskriftsartikel (refereegranskat)abstract
- We present a systematic study of charged-pion and kaon interferometry in Au + Au collisions at root s(NN) = 200 GeV. The kaon mean source radii are found to be larger than pion radii in the outward and longitudinal directions for the same transverse mass; this difference increases for more central collisions. The azimuthal-angle dependence of the radii was measured with respect to the second-order event plane and similar oscillations of the source radii were found for pions and kaons. Hydrodynamic models qualitatively describe the similar oscillations of the mean source radii for pions and kaons, but they do not fully describe the transverse-mass dependence of the oscillations.
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| 46. |
- Adcox, K, et al.
(författare)
-
Measurement of single electrons and implications for charm production in Au+Au collisions at root(NN)-N-S=130 GeV
- 2002
-
Ingår i: Physical Review Letters. - 1079-7114. ; 88:19
-
Tidskriftsartikel (refereegranskat)abstract
- Transverse momentum spectra of electrons from Au+Au collisions at roots(NN) = 130 GeV have been measured at midrapidity by the PHENIX experiment at the Relativistic Heavy Ion Collider. The spectra show an excess above the background from photon conversions and light hadron decays. The electron signal is consistent with that expected from semileptonic decays of charm. The yield of the electron signal dN(e)/dy for p(T) > 0.8 GeV/c is 0.025 +/- 0.004(stat) +/- 0.010( syst) in central collisions, and the corresponding charm cross section is 380 +/- 60(stat) +/- 200(syst ) mub per binary nucleon-nucleon collision.
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| 47. |
- Adler, S. S., et al.
(författare)
-
Detailed study of high-p(T) neutral pion suppression and azimuthal anisotropy in Au plus Au collisions at root s(NN) =200 GeV
- 2007
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Ingår i: Physical Review C (Nuclear Physics). - 0556-2813. ; 76:3
-
Tidskriftsartikel (refereegranskat)abstract
- Measurements of neutral pion (pi(0)) production at midrapidity in root s(NN)=200 GeV Au+Au collisions as a function of transverse momentum, p(T), collision centrality, and angle with respect to reaction plane are presented. The data represent the final pi(0) results from the PHENIX experiment for the first RHIC Au+Au run at design center-of-mass energy. They include additional data obtained using the PHENIX Level-2 trigger with more than a factor of 3 increase in statistics over previously published results for p(T)>6 GeV/c. We evaluate the suppression in the yield of high-p(T) pi(0)'s relative to pointlike scaling expectations using the nuclear modification factor R-AA. We present the p(T) dependence of R-AA for nine bins in collision centrality. We separately integrate R-AA over larger p(T) bins to show more precisely the centrality dependence of the high-p(T) suppression. We then evaluate the dependence of the high-p(T) suppression on the emission angle Delta phi of the pions with respect to event reaction plane for seven bins in collision centrality. We show that the yields of high-p(T) pi(0)'s vary strongly with Delta phi, consistent with prior measurements 1,2. We show that this variation persists in the most peripheral bin accessible in this analysis. For the peripheral bins we observe no suppression for neutral pions produced aligned with the reaction plane, whereas the yield of pi(0)'s produced perpendicular to the reaction plane is suppressed by a factor of similar to 2. We analyze the combined centrality and Delta phi dependence of the pi(0) suppression in different p(T) bins using different possible descriptions of parton energy loss dependence on jet path-length averages to determine whether a single geometric picture can explain the observed suppression pattern.
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| 48. |
-
Adaptive strategies in African arid lands : proceedings from a seminar at the Scandinavian Institute of African Studies, Uppsala, Sweden, April 1989
- 1990
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Proceedings (redaktörskap) (övrigt vetenskapligt/konstnärligt)abstract
- Adaptive strategies cannot be fully understood on the basis of environmental constraints alone. The essays presented in this book confirm this and provide material showing how environmental and socio-political processes interact in the making of adaption. The essays eludiate how manifestations of adaptability problems differ from region to region. such variations depend on the natural environment as well as the particular histories of development, socio-economic characteristics and the nature of the state. This collection of essays try to provide som answers to the problems emanating from different types of variation, and how they affect processes of adaption and change in African arid land.
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| 49. |
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| 50. |
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