Azimuthal anisotropy of direct photons in Au+Au collisions at βsNN=200GeV
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73 NUCLEAR PHYSICS AND RADIATION PHYSICSβ
Engineering topics
Chujo, T.
Publications and source records attributed to Chujo, T..
Erratum: Centrality-Dependent Modification of Jet-Production Rates in Deuteron-Gold Collisions at $\sqrt{π _{πβ’π}}$ = 200 GeV [Phys. Rev. Lett. 116, 122301 (2016)]
We previously reported jet-production rates in π + π and π + Au collisions at $\sqrt{π _{πβ’π}}$ = 200 GeV recorded in 2008 with the PHENIX detector at the Relativistic Heavy Ion Collider. Subsequently, we found that electronic noise in the electromagnetic calorimeter was not completely removed by the tower-timing cuts used in the analysis. We have conducted an independent re-analysis of the data that eliminated noisy towers by removing them completely from the analysis. These cuts remove any contributions from instrumental noise, but reduce the overall acceptance for electromagnetic clusters by β16% and hence the overall statistical power of the data. Finally, this re-analysis found that instrumental noise in the electromagnetic calorimeter led to an artificial increase in the jet yield for both the π + π and π + Au collisions.
73 NUCLEAR PHYSICS AND RADIATION PHYSICSβ
Design of the ECCE detector for the Electron Ion Collider
The EIC Comprehensive Chromodynamics Experiment (ECCE) detector has been designed to address the full scope of the proposed Electron Ion Collider (EIC) physics program as presented by the National Academy of Science and provide a deeper understanding of the quark-gluon structure of matter. To accomplish this, the ECCE detector offers nearly acceptance and energy coverage along with excellent tracking and particle identification. The ECCE detector was designed to be built within the budget envelope set out by the EIC project while simultaneously managing cost and schedule risks. Finally, this detector concept has been selected to be the basis for the EIC project detector.
47 OTHER INSTRUMENTATIONβ
Jet modification via π 0 -hadron correlations in Au + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV
High-momentum two-particle correlations are a useful tool for studying jet-quenching effects in the quark-gluon plasma. Angular correlations between neutral-pion triggers and charged hadrons with transverse momenta in the range 4β12 GeV/π and 0.5β7 GeV/π, respectively, have been measured by the PHENIX experiment in 2014 for Au + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV. Suppression is observed in the yield of high-momentum jet fragments opposite the trigger particle, which indicates jet suppression stemming from in-medium partonic energy loss, while enhancement is observed for low-momentum particles. The ratio and differences between the yield in Au + Au collisions and π + π collisions, πΌ π΄β’π΄ and Ξ π΄β’π΄ , as a function of the trigger-hadron azimuthal separation, Ξβ’π, are measured for the first time at the BNL Relativistic Heavy Ion Collider. Finally, these results better quantify how the yield of low-π π associated hadrons is enhanced at wide angle, which is crucial for studying energy loss as well as medium-response effects.
73 NUCLEAR PHYSICS AND RADIATION PHYSICSβ
Identified charged-hadron production in π+Al, 3 He + Au, and Cu + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV and in U + U collisions at $\sqrt{s_{NN}}$ = 193 GeV
The PHENIX experiment has performed a systematic study of identified charged-hadron (π Β± , πΎ Β± , π, $\bar{π}$) production at midrapidity in π + Al, 3 He + Au, and Cu + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV and U + U collisions at $\sqrt{s_{NN}}$ = 193 GeV. Identified charged-hadron invariant transverse-momentum (π π ) and transverse-mass (π π ) spectra are presented and interpreted in terms of radially expanding thermalized systems. The particle ratios of πΎ/π and π/π have been measured in different centrality ranges of large (Cu + Au and U + U) and small (π + Al and 3 He + Au) collision systems. The values of πΎ/π ratios measured in all considered collision systems were found to be consistent with those measured in π+π collisions. However, the values of π/π ratios measured in large collision systems reach the values of β0.6, which is a factor of β2 larger than in π + π collisions. These results can be qualitatively understood in terms of the baryon enhancement expected from hadronization by recombination. Identified charged-hadron nuclear-modification factors (π π΄β’π΅ ) are also presented. Enhancement of proton π π΄β’π΅ values over meson π π΄β’π΅ values was observed in central 3 He + Au, Cu + Au, and U + U collisions. Finally, the proton π π΄β’π΅ values measured in the π + Al collision system were found to be consistent with π π΄β’π΅ values of π, π Β± , πΎ Β± , and π 0 mesons, which may indicate that the size of the system produced in π + Al collisions is too small for recombination to cause a noticeable increase in proton production.
73 NUCLEAR PHYSICS AND RADIATION PHYSICSβ
Nonprompt direct-photon production in Au + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV
The measurement of the direct-photon spectrum from Au + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV is presented by the PHENIX Collaboration using the external-photon-conversion technique for 0%β93% central collisions in a transverse-momentum (π π ) range of 0.8β10 GeV/π. An excess of direct photons, above prompt-photon production from hard-scattering processes, is observed for π π < 6 GeV/π. Nonprompt direct photons are measured by subtracting the prompt component, which is estimated as π coll -scaled direct photons from π + π collisions at 200 GeV, from the direct-photon spectrum. Results are obtained for 0.8 < π π < 6.0 GeV/π and suggest that the spectrum has an increasing inverse slope from β0.2 to 0.4 GeV/π with increasing π π , which indicates a possible sensitivity of the measurement to photons from earlier stages of the evolution of the collision. In addition, like the direct-photon production, the π π -integrated nonprompt direct-photon yields also follow a power-law scaling behavior as a function of collision-system size. Finally, the exponent, πΌ, for the nonprompt component is found to be consistent with 1.1 with no apparent π π dependence.
73 NUCLEAR PHYSICS AND RADIATION PHYSICSβ
Charm- and bottom-quark production in Au+Au collisions at $$ \sqrt{{\textrm{s}}_{\textrm{NN}}} $$=200 GeV
Here, the invariant yield of electrons from open-heavy-flavor decays for 1 < p T < 8 GeV/c at midrapidity |y| < 0.35 in Au+Au collisions at $\sqrt{s_{NN}}$ = 200 GeV has been measured by the PHENIX experiment at the Relativistic Heavy Ion Collider. A displaced-vertex analysis with the PHENIX silicon-vertex detector enables extraction of the fraction of charm and bottom hadron decays and unfolding of the invariant yield of parent charm and bottom hadrons. The nuclear-modification factors RAA for electrons from charm and bottom hadron decays and heavy-flavor hadrons show both a centrality and a quark-mass dependence, indicating suppression in the quark-gluon plasma produced in these collisions that is medium sized and quark-mass dependent.
73 NUCLEAR PHYSICS AND RADIATION PHYSICSβ
Erratum: LΓ©vy-stable two-pion Bose-Einstein correlations in s N N = 200 GeV Au + Au collisions [Phys. Rev. C 97 , 064911 (2018)]
We previously published in 2018 a detailed measurement recorded in 2010 for Au+Au collisions at $\sqrt{^SNN}$ = 200 GeV of charged two-pion correlation functions in 0%-30% centrality. We found the data to be well described by Bose-Einstein correlation functions stemming from L$\acute{e}$vy-stable source distributions. Using a fine transverse momentum binning, we extracted the correlation strength parameter Ξ», the L$\acute{e}$vy index of stability Ξ± and the L$\acute{e}$vy length scale parameter R as a function of average transverse mass of the pair m T .
73 NUCLEAR PHYSICS AND RADIATION PHYSICSβ
Evaluation of longitudinal double-spin asymmetry measurements in semi-inclusive deep-inelastic scattering from the proton for the ECCE detector design
The evaluation of the measurement of double-spin asymmetries for charge-separated pions and kaons produced in deep-inelastic scattering from the proton using the ECCE detector design concept is presented, for the combinations of lepton and hadron beam energies of 5 Γ 41 GeV 2 and 18 Γ 275 GeV 2 . The study uses unpolarised simulated data that are processed through a full GEANT simulation of the detector. These data are then reweighted at the parton level with DSSV helicity distributions and DSS fragmentation functions, in order to generate the relevant asymmetries, and subsequently analysed. Furthermore, the performed analysis shows that the ECCE detector concept provides the resolution and acceptance, with a broad coverage in kinematic phase space, needed for a robust extraction of asymmetries. This, in turn, allows for a precise extraction of sea-quark helicity distributions.
73 NUCLEAR PHYSICS AND RADIATION PHYSICSβ
Design and simulated performance of calorimetry systems for the ECCE detector at the electron ion collider
Here, we describe the design and performance the calorimeter systems used in the ECCE detector to achieve the overall performance specifications cost-effectively with careful consideration of appropriate technical and schedule risks. The calorimeter systems consist of three electromagnetic calorimeters, covering the combined pseudorapidity range from -3.7 to 3.8 and two hadronic calorimeters covering a combined range of -1.1<Ξ·<3.8. Key calorimeter performances which include energy and position resolutions, reconstruction efficiency, and particle identification will be presented.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND β
ECCE unpolarized TMD measurements
For this work, we performed feasibility studies for various measurements that are related to unpolarized TMD distribution and fragmentation functions for the ECCE detector proposal. The processes studied include semi-inclusive Deep inelastic scattering (SIDIS) where single hadrons (pions and kaons) were detected in addition to the scattered DIS lepton. The single hadron cross sections and multiplicities were extracted as a function of the DIS variables x and Q 2 , as well as the semi-inclusive variables z, which corresponds to the momentum fraction the detected hadron carries relative to the struck parton and P T , which corresponds to the transverse momentum of the detected hadron relative to the virtual photon. The expected statistical precision of such measurements is extrapolated to accumulated luminosities of 10 fb β1 and potential systematic uncertainties are approximated given the deviations between true and reconstructed yields. The expected uncertainties are then used to obtain the expected impact on the related TMD distribution and fragmentation functions. We find that the ECCE detector proposal fulfills the physics requirements on these channels as detailed in the EIC Yellow Report.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND β
Measurement of Direct-Photon Cross Section and Double-Helicity Asymmetry at s = 510 GeV in p β + p β Collisions
Not Available
73 NUCLEAR PHYSICS AND RADIATION PHYSICSβ
Search for e β Ο charged lepton flavor violation at the EIC with the ECCE detector
The recently approved Electron-Ion Collider (EIC) will provide a unique new opportunity for searches of charged lepton flavor violation (CLFV) and other new physics scenarios. In contrast to the e β ΞΌ CLFV transition for which very stringent limits exist, there is still a relatively large discovery space for the e β Ο CLFV transition, potentially to be explored by the EIC. Here, with the latest detector design of ECCE (EIC Comprehensive Chromodynamics Experiment) and projected integral luminosity of the EIC, we find the Ο-leptons created in the DIS process ep β ΟX are expected to be identified with high efficiency. A first ECCE simulation study, restricted to the 3-prong Ο-decay mode and with limited statistics for the Standard Model backgrounds, estimates that the EIC will be able to improve the current exclusion limit on e β Ο CLFV by an order of magnitude. As a result, the very high vertex resolution of the ECCE detector configuration plays a critical role in Ο identification.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND β
Detector requirements and simulation results for the EIC exclusive, diffractive and tagging physics program using the ECCE detector concept
This article presents a collection of simulation studies using the ECCE detector concept in the context of the EICβs exclusive, diffractive, and tagging physics program, which aims to further explore the rich quarkβgluon structure of nucleons and nuclei. To successfully execute the program, ECCE proposed to utilize the detector system close to the beamline to ensure exclusivity and tag ion beam/fragments for a particular reaction of interest. Preliminary studies confirm the proposed technology and design satisfy the requirements. Further, the projected physics impact results are based on the projected detector performance from the simulation at 10 or 100 fb -1 of integrated luminosity. Additionally, insights related to a potential second EIC detector are documented, which could serve as a guidepost for future development.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND β
Low-$p_T$ direct-photon production in Au + Au collisions at $\sqrt{s_{NN}}$ = 39 and 62.4 GeV
Here, the measurement of direct photons from Au + Au collisions at $\sqrt{s_{NN}}$ = 39 and 62.4 GeV in the transverse-momentum range 0.4 < $p_T$ < 3 Gev/c is presented by the PHENIX collaboration at the BNLRelativistic Heavy Ion Collider. A significant direct-photon yield is observed in both collision systems. A universal scaling is observed when the direct-photon $p_T$ spectra for different center-of-mass energies and for different centrality selections at $\sqrt{s_{NN}}$ = 62.4 GeV is scaled with $(dN_{\text{ch}}/dΞ·)^Ξ±$ for Ξ± = 1.21 Β± 0.04. This scaling also holds true for direct-photon spectra from Au + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV measured earlier by PHENIX, as well as the spectra from Pb + Pb at $\sqrt{s_{NN}}$ = 2760 GeV published by ALICE. The scaling power Ξ± seems to be independent of $p_T$, center of mass energy, and collision centrality. The spectra from different collision energies have a similar shape up to $p_T$ of 2 Gev/c. The spectra have a local inverse slope $T_{\text{eff}}$ increasing with $p_T$ of 0.174 Β± 0.018 Gev/c in the range 0.4 < $p_T$ < 1.3 Gev/c and increasing to 0.289 Β± 0.024 Gev/c for 0.9 < $p_T$ < 2.1 Gev/c. The observed similarity of low-$p_T$ direct-photon production from $\sqrt{s_{NN}}$ = 39 to 2760 GeV suggests a common source of direct photons for the different collision energies and event centrality selections, and suggests a comparable space-time evolution of direct-photon emission.
73 NUCLEAR PHYSICS AND RADIATION PHYSICSβ
Measurements of second-harmonic Fourier coefficients from azimuthal anisotropies in p + p , p + Au , d + Au , and He 3 + Au collisions at s N N = 200 GeV
Recently, the PHENIX Collaboration has published second- and third-harmonic Fourier coefficients v 2 and v 3 for midrapidity (|Ξ·|< 0.35 ) charged hadrons in 0%β5% central p+Au, d+Au, and 3 He+Au collisions at $\sqrt{s_{NN}}$= 200 GeV, utilizing three sets of two-particle correlations for two detector combinations with different pseudorapidity acceptance [Acharya et al., Phys. Rev. C 105, 024901 (2022)]. Here, this paper extends these measurements of v 2 to all centralities in p+Au, d+Au, and 3 He+Au collisions, as well as p+p collisions, as a function of transverse momentum (p T ) and event multiplicity. The kinematic dependence of v 2 is quantified as the ratio R of v 2 between the two detector combinations as a function of event multiplicity for 0.5 < p T <1 and 2 T < 2.5 GeV/c. A multiphase-transport (AMPT) model can reproduce the observed v 2 in most-central to midcentral d Au and 3 He+Au collisions. However, the AMPT model systematically overestimates the measurements in p+p, p+Au, and peripheral d+Au and 3 He+Au collisions, indicating a higher nonflow contribution in the AMPT model than in the experimental data. The AMPT model fails to describe the observed R for 0.5 < p T < 1 GeV/c , but there is qualitative agreement with the measurements for 2 < p T < 2.5 GeV/c.
73 NUCLEAR PHYSICS AND RADIATION PHYSICSβ
Measurement of Ο-meson production in Cu + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV and U + U collisions at $\sqrt{s_{NN}}$ = 193 GeV
The PHENIX experiment reports systematic measurements at the Relativistic Heavy Ion Collider of Ο-meson production in asymmetric Cu + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV and in U + U collisions at $\sqrt{s_{NN}}$ = 193 GeV. Measurements were performed via the Ο β K + K β decay channel at midrapidity |Ξ·| < 0.35. Features of Ο- meson production measured in Cu + Cu, Cu + Au, Au + Au, and U + U collisions were found to not depend on the collision geometry, which was expected because the yields are averaged over the azimuthal angle and follow the expected scaling with nuclear-overlap size. The elliptic flow of the Ο meson in Cu + Au, Au + Au, and U + U collisions scales with second-order-participant eccentricity and the length scale of the nuclear-overlap region (estimated with the number of participating nucleons). At moderate $p_T$ , Ο-meson production measured in Cu + Au and U + U collisions is consistent with coalescence-model predictions, whereas at high $p_T$ the production is in agreement with expectations for in-medium energy loss of parent partons prior to their fragmentation. Finally, the elliptic flow for Ο mesons measured in Cu + Au and U + U collisions is well described by a (2+1)-dimensional viscous-hydrodynamic model with specific-shear viscosity Ξ·/s = 1/4Ο.
73 NUCLEAR PHYSICS AND RADIATION PHYSICSβ
ECCE sensitivity studies for single hadron transverse single spin asymmetry measurements
Here, we performed feasibility studies for various single transverse spin measurements that are related to the Sivers effect, transversity and the tensor charge, and the Collins fragmentation function. The processes studied include semi-inclusive deep inelastic scattering (SIDIS) where single hadrons (pions and kaons) were detected in addition to the scattered DIS lepton. The data were obtained in pythia6 and geant4 simulated e+p collisions at 18 GeV on 275 GeV, 18 on 100, 10 on 100, and 5 on 41 that use the ECCE detector configuration. Typical DIS kinematics were selected, most notably Q 2 >1 GeV 2 , and cover the x range from 10 -4 to 1. The single spin asymmetries were extracted as a function of x and Q 2 , as well as the semi-inclusive variables z, which corresponds to the momentum fraction the detected hadron carries relative to the struck parton, and P T , which corresponds to the transverse momentum of the detected hadron relative to the virtual photon. They are obtained in azimuthal moments in combinations of the azimuthal angles of the hadron transverse momentum and transverse spin of the nucleon relative to the lepton scattering plane. In order to extract asymmetries, the initially unpolarized MonteCarlo was re-weighted in the true kinematic variables, hadron types and parton flavors based on global fits of fixed target SIDIS experiments and e + e β annihilation data. The expected statistical precision of such measurements is extrapolated to 10 fb β1 and potential systematic uncertainties are approximated given the deviations between true and reconstructed yields. Similar neutron information is obtained by comparing the ECCE e+p pseudo-data with the same from the EIC Yellow Report and scaling the corresponding Yellow Report e+ 3 He pseudo-data uncertainties accordingly. The impact on the knowledge of the Sivers functions, transversity and tensor charges, and the Collins function has then been evaluated in the same phenomenological extractions as in the Yellow Report. Finally, the impact is found to be comparable to that obtained with the parametrized Yellow Report detector and shows that the ECCE detector configuration can fulfill the physics goals on these quantities.
46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND β