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Cheng, J.

Publications and source records attributed to Cheng, J..

At least 145 records · Page 8
All sourcesNASA NTRSDOE OSTI
DOE OSTI2019

Beam energy dependence of (anti-)deuteron production in Au + Au collisions at the BNL Relativistic Heavy Ion Collider

Here, we report the energy dependence of mid-rapidity (anti-)deuteron production in Au+Au collisions at $ \sqrt{s_{NN}}$ = 7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV, measured by the STAR experiment at RHIC. The yield of deuterons is found to be well described by the thermal model. The collision energy, centrality, and transverse momentum dependence of the coalescence parameter B 2 are discussed. We find that the values of B 2 for antideuterons are systematically lower than those for deuterons, indicating that the correlation volume of antibaryons is larger than that of baryons at $ \sqrt{s_{NN}}$ from 19.6 to 39 GeV. In addition, values of B 2 are found to vary with collision energy and show a broad minimum around $ \sqrt{s_{NN}}$ = 20 to 40 GeV, which might imply a change of the equation of state of the medium in these collisions.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

A high precision calibration of the nonlinear energy response at Daya Bay

A high precision calibration of the nonlinearity in the energy response of the Daya Bay Reactor Neutrino Experiment’s antineutrino detectors is observed. The energy nonlinearity originates from the particle-dependent light yield of the scintillator and charge-dependent electronics response. The nonlinearity model is constrained by γ calibration points from deployed and naturally occurring radioactive sources, the β spectrum from 12 B decays, and a direct measurement of the electronics nonlinearity with a new flash analog-to-digital converter readout system. With this beind said, less than 0.5% uncertainty in the energy nonlinearity calibration is achieved for positrons of kinetic energies greater than 1 MeV.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

Azimuthal Harmonics in Small and Large Collision Systems at RHIC Top Energies

The first (v$even\atop{1}$), second (v 2 ) and third (v 3 ) harmonic coefficients of the azimuthal particle distribution at mid-rapidity, are extracted for charged hadrons and studied as a function of transverse momentum (p T ) and mean charged particle multiplicity density $\langle$N ch $\rangle$ in U+U ($\sqrt{s_ {NN}}$ = 193 GeV), Au+Au, Cu+Au, Cu+Cu, d+Au and p+Au collisions at $\sqrt{s_ {NN}}$ = 200 GeV with the STAR Detector. For the same $\langle$N ch $\rangle$, the v$even\atop{1}$ and v 3 coefficients are observed to be independent of collision system, while v 2 exhibits such a scaling only when normalized by the initial-state eccentricity (ε 2 ). The data also show that ln(v 2 /ε 2 ) scales linearly with $\langle$N ch $\rangle$ -1/3 . Finally, these measurements provide insight into initial-geometry fluctuations and the role of viscous hydrodynamic attenuation on v n from small to large collision systems.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

Collision-energy dependence of p t correlations in Au + Au collisions at energies available at the BNL Relativistic Heavy Ion Collider

We present two-particle $p_{\rm t}$ correlations as a function of event centrality for Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 7.7, 11.5, 14.5, 19.6, 27, 39, 62.4, and 200 GeV at the Relativistic Heavy Ion Collider using the STAR detector. These results are compared to previous measurements from CERES at the Super Proton Synchrotron and from ALICE at the Large Hadron Collider. The data are compared with UrQMD model calculations and with a model based on a Boltzmann-Langevin approach incorporating effects from thermalization. The relative dynamical correlations for Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 200 GeV show a power law dependence on the number of participant nucleons and agree with the results for Pb+Pb collisions at $\sqrt{s_{\rm NN}} = 2.76~ {\rm TeV}$ from ALICE. As the collision energy is lowered from $\sqrt{s_{\rm NN}}$ = 200 GeV to 7.7 GeV, the centrality dependence of the relative dynamical correlations departs from the power law behavior observed at the higher collision energies. In central collisions, the relative dynamical correlations increase with collision energy up to $\sqrt{s_{\rm NN}}$ = 200 GeV in contrast to previous measurements that showed little dependence on the collision energy.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

Centrality and transverse momentum dependence of D 0 -meson production at mid-rapidity in Au + Au collisions at s NN = 200 GeV

Here, we report a new measurement of D 0 -meson production at mid-rapidity (| y | < 1) in Au + Au collisions at $\sqrt{s}$$_ {NN}$ = 200 GeV utilizing the heavy flavor tracker, a high resolution silicon detector at the STAR experiment. Invariant yields of D 0 mesons with transverse momentum p T ≲ 9 GeV / c are reported in various centrality bins (0–10%, 10–20%, 20–40%, 40–60%, and 60–80%). Blast-wave thermal models are used to fit the D 0 -meson p T spectra to study D 0 hadron kinetic freeze-out properties. The average radial flow velocity extracted from the fit is considerably smaller than that of light hadrons (π, K, and p), but comparable to that of hadrons containing multiple strange quarks (Φ, Ξ - ) , indicating that D 0 mesons kinetically decouple from the system earlier than light hadrons. The calculated D 0 nuclear modification factors reaffirm that charm quarks suffer a large amount of energy loss in the medium, similar to those of light quarks for p T > 4 GeV/c in central 0–10% Au + Au collisions. At low p T , the nuclear modification factors show a characteristic structure qualitatively consistent with the expectation from model predictions that charm quarks gain sizable collective motion during the medium evolution. The improved measurements are expected to offer new constraints to model calculations and help gain further insights into the hot and dense medium created in these collisions.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2019

Global and local polarization of Λ hyperons in Au+Au collisions at 200 GeV from STAR

New results on global polarization of Λ hyperons in Au+Au collisions at √ s NN = 200 GeV reveal non-zero signal on the order of a few tenths of a percent. Compared with lower energy results, the current measurement shows that the polarization decreases at higher collision energy, the trend being well reproduced by theoretical calculations. The polarization is found to be larger in more peripheral collisions, as well as in the in-plane than in the out-of-plane direction. The signal seems to depend on the asymmetry between positive and negative charge in each event, which may indicate an influence of the axial current induced by the magnetic field. In addition, the first measurement of a local polarization along the beam direction was performed. The results show a quadrupole modulation relative to the second-order event plane, as expected from the elliptic flow.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2018

Regulation of connexin 43 expression in human gingival fibroblasts

Highlights: ●Wound healing-associated cytokines modulate connexin 43 abundance in human gingival fibroblasts. ●Interplay between these cytokines distinctly determines connexin 43 abundance via transcriptional/post-transcriptional and translational/post-translational mechanisms. ●TGF-β-induced upregulation of connexin 43 is mediated by SMAD2/3 pathway. ●TNF-α, IL-1β, IFN-γ and PGE2 inhibit TGF-β-induced connexin 43 upregulation by suppressing SMAD2/3 phosphorylation. Abundance of connexin 43 (Cx43), a transmembrane protein that forms hemichannels (HCs) and gap junctions (GJs), is dynamically regulated in human gingival fibroblasts (GFBLs) during wound healing. This may be important for fast and scarless gingival wound healing as Cx43 is involved in key cell functions important during this process. Our aim was to uncover the factors that regulate Cx43 expression and abundance in GFBLs. We hypothesized that cytokines and growth factors released during wound healing coordinately regulate Cx43 abundance in GFBLs.

60 APPLIED LIFE SCIENCES↗