(R)-Doxylaminium (R,R)-tartrate

In the title compound (systematic name: (R)-dimeth­yl{2-[1-phenyl-1-(pyridin-2-yl)eth­oxy]eth­yl}aza­nium (R,R)-3-carb­oxy-2,3-dihy­droxy­propano­ate), C17H23N2O+·C4H5O6 −, the doxylaminium cation is protonated at the N atom. The tartrate monoanions are linked by short, almost linear O—H⋯O hydrogen bonds into chains extended along [100]. These chains are inter­linked by anion–pyridine O—H⋯N hydrogen bonds into a two-dimensional grid structure. WeakC—H⋯O inter­actions also play a role in the crystal packing. An intra­molecular hy­droxy–carboxyl­ate O—H⋯O hydrogen bond influences the conformation of the anion: the hydrogen-bonded fragment is almost planar, the maximum deviation from the mean plane being 0.059 (14) Å. In the cation, the aromatic rings are almost perpendicular [dihedral angle = 84.94 (8)°] and the conformation of the O—C—C—N chain is gauche(−), the dihedral angle is −76.6 (2)°. The absolute configuration was assigned on the basis of known chirality of the parent compound

Systematic study of nuclear effects in pp ++Al, pp ++Au, dd ++Au, and 3^{3}He++Au collisions at sNN=200\sqrt{s_{_{NN}}}=200 GeV using π0\pi^0 production

International audienceThe PHENIX collaboration presents a systematic study of $\pi^0$ production from $p$ $+$ $p$, $p$ $+$Al, $p$ $+$Au, $d$ $+$Au, and $^{3}$He$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV. Measurements were performed with different centrality selections as well as the total inelastic, 0%--100%, selection for all collision systems. For 0%--100% collisions, the nuclear modification factors, $R_{xA}$, are consistent with unity for $p_T$ above 8 GeV/$c$, but exhibit an enhancement in peripheral collisions and a suppression in central collisions. The enhancement and suppression characteristics are similar for all systems for the same centrality class. It is shown that for high-$p_T$-$\pi^0$ production, the nucleons in the $d$ and $^3$He interact mostly independently with the Au nucleus and that the counter intuitive centrality dependence is likely due to a physical correlation between multiplicity and the presence of a hard scattering process. These observations disfavor models where parton energy loss has a significant contribution to nuclear modifications in small systems. Nuclear modifications at lower $p_T$ resemble the Cronin effect -- an increase followed by a peak in central or inelastic collisions and a plateau in peripheral collisions. The peak height has a characteristic ordering by system size as $p$ $+$Au $>$ $d$ $+$Au $>$ $^{3}$He$+$Au $>$ $p$ $+$Al. For collisions with Au ions, current calculations based on initial state cold nuclear matter effects result in the opposite order, suggesting the presence of other contributions to nuclear modifications, in particular at lower $p_T$

Systematic study of nuclear effects in pp ++Al, pp ++Au, dd ++Au, and 3^{3}He++Au collisions at sNN=200\sqrt{s_{_{NN}}}=200 GeV using π0\pi^0 production

International audienceThe PHENIX Collaboration presents a systematic study of inclusive π0 production from p+p, p+Al, p+Au, d+Au, and He3+Au collisions at sNN=200GeV. Measurements were performed with different centrality selections as well as the total inelastic, 0–100%, selection for all collision systems. For 0–100% collisions, the nuclear-modification factors, RxA, are consistent with unity for pT above 8GeV/c, but exhibit an enhancement in peripheral collisions and a suppression in central collisions. The enhancement and suppression characteristics are similar for all systems for the same centrality class. It is shown that for high-pT-π0 production, the nucleons in the d and He3 interact mostly independently with the Au nucleus and that the counterintuitive centrality dependence is likely due to a physical correlation between multiplicity and the presence of a hard scattering process. These observations disfavor models where parton energy loss has a significant contribution to nuclear modifications in small systems. Nuclear modifications at lower pT resemble the Cronin effect—an increase followed by a peak in central or inelastic collisions and a plateau in peripheral collisions. The peak height has a characteristic ordering by system size as p+Au>d+Au>He3+Au>p+Al. For collisions with Au ions, current calculations based on initial-state cold nuclear matter effects result in the opposite order, suggesting the presence of other contributions to nuclear modifications, in particular at lower pT

ϕ\phi meson production in the forward/backward rapidity region in Cu++Au collisions at sNN=200\sqrt{s_{NN}}=200 GeV

International audienceThe PHENIX experiment at the Relativistic Heavy Ion Collider has measured ϕ meson production and its nuclear modification in asymmetric Cu+Au heavy-ion collisions at sNN=200 GeV at both forward Cu-going direction (1.2<y<2.2) and backward Au-going direction (−2.2<y<−1.2) rapidities. The measurements are performed via the dimuon decay channel and reported as a function of the number of participating nucleons, rapidity, and transverse momentum. In the most central events, 0%–20% centrality, the ϕ meson yield integrated over 1<pT<5 GeV/c prefers a smaller value, which means a larger nuclear modification, in the Cu-going direction compared to the Au-going direction. Additionally, the nuclear-modification factor in Cu+Au collisions averaged over all centrality is measured to be similar to the previous PHENIX result in d+Au collisions for these rapidities