arXiv subjects

D. E. Fields

Publications and source records attributed to D. E. Fields.

At least 37 records · Page 2Linked to original sources

arXiv2023

Lévy-stable two-pion Bose-Einstein correlations in $\sqrt{s_{_{NN}}}=200$ GeV Au$+$Au collisions

We present a detailed measurement of charged two-pion correlation functions in 0%-30% centrality $\sqrt{s_{_{NN}}}=200$ GeV Au$+$Au collisions by the PHENIX experiment at the Relativistic Heavy Ion Collider. The data are well described by Bose-Einstein correlation functions stemming from Lévy-stable source distributions. Using a fine transverse momentum binning, we extract the correlation strength parameter $λ$, the Lévy index of stability $α$ and the Lévy length scale parameter $R$ as a function of average transverse mass of the pair $m_T$. We find that the positively and the negatively charged pion pairs yield consistent results, and their correlation functions are represented, within uncertainties, by the same Lévy-stable source functions. The $λ(m_T)$ measurements indicate a decrease of the strength of the correlations at low $m_T$. The Lévy length scale parameter $R(m_T)$ decreases with increasing $m_T$, following a hydrodynamically predicted type of scaling behavior. The values of the Lévy index of stability $α$ are found to be significantly lower than the Gaussian case of $α=2$, but also significantly larger than the conjectured value that may characterize the critical point of a second-order quark-hadron phase transition.

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arXiv2023

Transverse single-spin asymmetry of midrapidity $π^{0}$ and $η$ mesons in $p$+Au and $p$+Al collisions at $\sqrt{s_{_{NN}}}=$ 200 GeV

Presented are the first measurements of the transverse single-spin asymmetries ($A_N$) for neutral pions and eta mesons in $p$+Au and $p$+Al collisions at $\sqrt{s_{_{NN}}}=200$ GeV in the pseudorapidity range $|η|<$0.35 with the PHENIX detector at the Relativistic Heavy Ion Collider. The asymmetries are consistent with zero, similar to those for midrapidity neutral pions and eta mesons produced in $p$+$p$ collisions. These measurements show no evidence of additional effects that could potentially arise from the more complex partonic environment present in proton-nucleus collisions.

hep-ex↗

arXiv2023

Measurement of Direct-Photon Cross Section and Double-Helicity Asymmetry at $\sqrt{s}=510$ GeV in $\vec{p}+\vec{p}$ Collisions

We present measurements of the cross section and double-helicity asymmetry $A_{LL}$ of direct-photon production in $\vec{p}+\vec{p}$ collisions at $\sqrt{s}=510$ GeV. The measurements have been performed at midrapidity ($|η|<0.25$) with the PHENIX detector at the Relativistic Heavy Ion Collider. At relativistic energies, direct photons are dominantly produced from the initial quark-gluon hard scattering and do not interact via the strong force at leading order. Therefore, at $\sqrt{s}=510$ GeV, where leading-order-effects dominate, these measurements provide clean and direct access to the gluon helicity in the polarized proton in the gluon-momentum-fraction range $0.02<x<0.08$, with direct sensitivity to the sign of the gluon contribution.

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arXiv2023

Improving constraints on gluon spin-momentum correlations in transversely polarized protons via midrapidity open-heavy-flavor electrons in $p^{\uparrow}+p$ collisions at $\sqrt{s}=200$ GeV

Polarized proton-proton collisions provide leading-order access to gluons, presenting an opportunity to constrain gluon spin-momentum correlations within transversely polarized protons and enhance our understanding of the three-dimensional structure of the proton. Midrapidity open-heavy-flavor production at $\sqrt{s}=200$ GeV is dominated by gluon-gluon fusion, providing heightened sensitivity to gluon dynamics relative to other production channels. Transverse single-spin asymmetries of positrons and electrons from heavy-flavor hadron decays are measured at midrapidity using the PHENIX detector at the Relativistic Heavy Ion Collider. These charge-separated measurements are sensitive to gluon correlators that can in principle be related to gluon orbital angular momentum via model calculations. Explicit constraints on gluon correlators are extracted for two separate models, one of which had not been constrained previously.

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arXiv2023

Measurements of second-harmonic Fourier coefficients from azimuthal anisotropies in $p$$+$$p$, $p$$+$Au, $d$$+$Au, and $^3$He$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV

Recently, the PHENIX Collaboration has published second- and third-harmonic Fourier coefficients $v_2$ and $v_3$ for midrapidity ($|η|<0.35$) charged hadrons in 0\%--5\% 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 [Phys. Rev. C {\bf 105}, 024901 (2022)]. 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$$<$$p_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$$+$Au and $^3$He$+$Au collisions, indicating a higher nonflow contribution in AMPT than in the experimental data. The AMPT model fails to describe the observed $R$ for $0.5$$<$$p_T$$<$$1$ GeV/$c$, but there is qualitative agreement with the measurements for $2$$<$$p_T$$<$$2.5$ GeV/$c$.

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arXiv2023

Low-$p_T$ direct-photon production in Au$+$Au collisions at $\sqrt{s_{_{NN}}}=39$ and 62.4 GeV

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 Relativistic 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 $(dN_{\rm ch}/dη)^α$ for $α=1.21{\pm}0.04$. 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 $α$ 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 $T_{\rm eff}$ increasing with $p_T$ of $0.174\pm0.018$ GeV/$c$ in the range $0.4<p_T<1.3$ GeV/$c$ and increasing to $0.289\pm0.024$ 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.

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arXiv2023

Measurement of $ϕ$-meson production in Cu$+$Au at $\sqrt{s_{_{NN}}}=200$ GeV and U$+$U at $\sqrt{s_{_{NN}}}=193$ GeV

The PHENIX experiment reports systematic measurements at the Relativistic Heavy Ion Collider of $ϕ$-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 $ϕ\rightarrow K^{+}K^{-}$ decay channel at midrapidity $|η|<0.35$. Features of $ϕ$-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 $ϕ$ 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 $p_T$, $ϕ$-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. The elliptic flow for $ϕ$ mesons measured in Cu$+$Au and U$+$U collisions is well described by a (2+1)D viscous-hydrodynamic model with specific-shear viscosity $η/s=1/4π$.

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arXiv2022

Neutrinoless Double Beta Decay

This White Paper, prepared for the Fundamental Symmetries, Neutrons, and Neutrinos Town Meeting related to the 2023 Nuclear Physics Long Range Plan, makes the case for double beta decay as a critical component of the future nuclear physics program. The major experimental collaborations and many theorists have endorsed this white paper.

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arXiv2022

Study of $ϕ$-meson production in $p$$+$Al, $p$$+$Au, $d$$+$Au, and $^3$He$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV

Small nuclear collisions are mainly sensitive to cold-nuclear-matter effects; however, the collective behavior observed in these collisions shows a hint of hot-nuclear-matter effects. The identified-particle spectra, especially the $ϕ$ mesons which contain strange and antistrange quarks and have a relatively small hadronic-interaction cross section, are a good tool to study these effects. The PHENIX experiment has measured $ϕ$ mesons in a specific set of small collision systems $p$$+$Al, $p$$+$Au, and $^3$He$+$Au, as well as $d$$+$Au [Phys. Rev. C {\bf 83}, 024909 (2011)], at $\sqrt{s_{_{NN}}}=200$ GeV. The transverse-momentum spectra and nuclear-modification factors are presented and compared to theoretical-model predictions. The comparisons with different calculations suggest that quark-gluon plasma may be formed in these small collision systems at $\sqrt{s_{_{NN}}}=200$ GeV. However, the volume and the lifetime of the produced medium may be insufficient for observing strangeness-enhancement and jet-quenching effects. Comparison with calculations suggests that the main production mechanisms of $ϕ$ mesons at midrapidity may be different in $p$$+$Al versus $p/d/$$^3$He$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV. While thermal quark recombination seems to dominate in $p/d/$$^3$He$+$Au collisions, fragmentation seems to be the main production mechanism in $p$$+$Al collisions.

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arXiv2022

Understanding the Enhancement of Scintillation Light in Xenon-Doped Liquid Argon

Measuring the scintillation light in noble gases is an important detection technique in particle physics. Numerous rare event searches like neutrino beam experiments, neutrino-less double beta-decay, and dark matter searches use argon-based detectors. In liquid argon, the light yield can be enhanced by the addition of a small quantity of xenon, where $\sim 10 - 1000$ ppm are added. The general enhancement mechanism and its pathway via an energy transfer between argon and xenon excimers is well known, however the importance of absorption of argon excimer emission by atomic xenon has not been fully appreciated. This absorption significantly reduces the light yield in commercially available argon which contains trace amounts ($\rm \sim 0.1$ ppm) of xenon. The addition of a small xenon dopant of $\sim 10$ ppm recovers this lost light resulting in an increased light yield over un-doped argon of about a factor of two. In this paper we introduce a model for the light production in xenon doped argon, including absorption and re-emission, and compare it to the measured time dependence of light emission in xenon-doped argon.

physics.ins-det↗

arXiv2022

Measurement of $ψ(2S)$ nuclear modification at backward and forward rapidity in $p$$+$$p$, $p$$+$Al, and $p$$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV

Suppression of the $J/ψ$ nuclear-modification factor has been seen as a trademark signature of final-state effects in large collision systems for decades. In small systems, the nuclear modification was attributed to cold-nuclear-matter effects until the observation of strong differential suppression of the $ψ(2S)$ state in $p/d$$+$$A$ collisions suggested the presence of final-state effects. Results of $J/ψ$ and $ψ(2S)$ measurements in the dimuon decay channel are presented here for $p$$+$$p$, $p$$+$Al, and $p$$+$Au collision systems at $\sqrt{s_{_{NN}}}=200$ GeV. The results are predominantly shown in the form of the nuclear-modification factor, $R_{pA}$, the ratio of the $ψ(2S)$ invariant yield per nucleon-nucleon collision in collisions of proton on target nucleus to that in $p$$+$$p$ collisions. Measurements of the $J/ψ$ and $ψ(2S)$ nuclear-modification factor are compared with shadowing and transport-model predictions, as well as to complementary measurements at Large-Hadron-Collider energies.

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arXiv2022

Transverse-single-spin asymmetries of charged pions at midrapidity in transversely polarized $p{+}p$ collisions at $\sqrt{s}=200$ GeV

In 2015, the PHENIX collaboration has measured single-spin asymmetries for charged pions in transversely polarized proton-proton collisions at the center of mass energy of $\sqrt{s}=200$ GeV. The pions were detected at central rapidities of $|η|<0.35$. The single-spin asymmetries are consistent with zero for each charge individually, as well as consistent with the previously published neutral-pion asymmetries in the same rapidity range. However, they show a slight indication of charge-dependent differences which may suggest a flavor dependence in the underlying mechanisms that create these asymmetries.

hep-ex↗

arXiv2022

Transverse single spin asymmetries of forward neutrons in $p$$+$$p$, $p$$+$Al, and $p$$+$Au collisions at $\sqrt{s_{_{NN}}}=200$ GeV as a function of transverse and longitudinal momenta

In 2015 the PHENIX collaboration at the Relativistic Heavy Ion Collider recorded $p$$+$$p$, $p$$+$Al, and $p$$+$Au collision data at center of mass energies of $\sqrt{s_{_{NN}}}=200$ GeV with the proton beam(s) transversely polarized. At very forward rapidities $η>6.8$ relative to the polarized proton beam, neutrons were detected either inclusively or in (anti)correlation with detector activity related to hard collisions. The resulting single spin asymmetries, that were previously reported, have now been extracted as a function of the transverse momentum of the neutron as well as its longitudinal momentum fraction $x_F$. The explicit kinematic dependence, combined with the correlation information allows for a closer look at the interplay of different mechanisms suggested to describe these asymmetries, such as hadronic interactions or electromagnetic interactions in ultra-peripheral collisions, UPC. Events that are correlated with a hard collision indeed display a mostly negative asymmetry that increases in magnitude as a function of transverse momentum with only little dependence on $x_F$. In contrast, events that are not likely to have emerged from a hard collision display positive asymmetries for the nuclear collisions with a kinematic dependence that resembles that of a UPC based model. Because the UPC interaction depends strongly on the charge of the nucleus, those effects are very small for $p$$+$$p$ collisions, moderate for $p$$+$Al collisions, and large for $p$$+$Au collisions.

hep-ex↗

arXiv2022

Kinematic dependence of azimuthal anisotropies in $p$$+$Au, $d$$+$Au, $^3$He+Au at $\sqrt{s_{_{NN}}}$ = 200 GeV

There is strong evidence for the formation of small droplets of quark-gluon plasma in $p/d/^{3}$He+Au collisions at the Relativistic Heavy Ion Collider (RHIC) and in $p$+$p$/Pb collisions at the Large Hadron Collider. In particular, the analysis of data at RHIC for different geometries obtained by varying the projectile size and shape has proven insightful. In the present analysis, we find excellent agreement with the previously published PHENIX at RHIC results on elliptical and triangular flow with an independent analysis via the two-particle correlation method, which has quite different systematic uncertainties and an independent code base. In addition, the results are extended to other detector combinations with different kinematic (pseudorapidity) coverage. These results provide additional constraints on contributions from nonflow and longitudinal decorrelations.

hep-ex↗

arXiv2021

Probing gluon spin-momentum correlations in transversely polarized protons through midrapidity isolated direct photons in $p^\uparrow+p$ collisions at $\sqrt{s}=200$ GeV

Studying spin-momentum correlations in hadronic collisions offers a glimpse into a three-dimensional picture of proton structure. The transverse single-spin asymmetry for midrapidity isolated direct photons in $p^\uparrow+p$ collisions at $\sqrt{s}=200$ GeV is measured with the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC). Because direct photons in particular are produced from the hard scattering and do not interact via the strong force, this measurement is a clean probe of initial-state spin-momentum correlations inside the proton and is in particular sensitive to gluon interference effects within the proton. This is the first time direct photons have been used as a probe of spin-momentum correlations at RHIC. The uncertainties on the results are a fifty-fold improvement with respect to those of the one prior measurement for the same observable, from the Fermilab E704 experiment. These results constrain gluon spin-momentum correlations in transversely polarized protons.

hep-ex↗

arXiv2021

LEGEND-1000 Preconceptual Design Report

We propose the construction of LEGEND-1000, the ton-scale Large Enriched Germanium Experiment for Neutrinoless $ββ$ Decay. This international experiment is designed to answer one of the highest priority questions in fundamental physics. It consists of 1000 kg of Ge detectors enriched to more than 90% in the $^{76}$Ge isotope operated in a liquid argon active shield at a deep underground laboratory. By combining the lowest background levels with the best energy resolution in the field, LEGEND-1000 will perform a quasi-background-free search and can make an unambiguous discovery of neutrinoless double-beta decay with just a handful of counts at the decay $Q$ value. The experiment is designed to probe this decay with a 99.7%-CL discovery sensitivity in the $^{76}$Ge half-life of $1.3\times10^{28}$ years, corresponding to an effective Majorana mass upper limit in the range of 9-21 meV, to cover the inverted-ordering neutrino mass scale with 10 yr of live time.

physics.ins-det↗

arXiv2021

Large-Scale, Precision Xenon Doping of Liquid Argon

The detection of scintillation light from liquid argon is an experimental technique key to a number of current and future nuclear/particle physics experiments, such as neutrino physics, neutrinoless double beta decay and dark matter searches. Although the idea of adding small quantities of xenon (doping) to enhance the light yield has attracted considerable interest, this technique has never been demonstrated at the necessary scale or precision. Here we report on xenon doping in a 100 l cryogenic vessel. Xenon doping was performed in four concentrations of 1.00$\pm$0.06 ppm, 2.0$\pm$0.1 ppm, 5.0$\pm$0.3 ppm, and 10.0$\pm$0.5 ppm. These measurements represent the most precise xenon doping measurements as of publishing. We observed an increase in average light yield by a factor of 1.92$\pm$0.12(syst)$\pm$0.02(stat) at a dopant concentration of 10 ppm.

physics.ins-det↗

arXiv2021

Transverse single-spin asymmetries of midrapidity $π^0$ and $η$ mesons in polarized $p$$+$$p$ collisions at $\sqrt{s}=200$ GeV

We present a measurement of the transverse single-spin asymmetry for $π^0$ and $η$ mesons in $p^\uparrow$$+$$p$ collisions in the pseudorapidity range $|η|<0.35$ and at a center-of-mass energy of 200 GeV with the PHENIX detector at the Relativistic Heavy Ion Collider. In comparison with previous measurements in this kinematic region, these results have a factor of 3 smaller uncertainties. As hadrons, $π^0$ and $η$ mesons are sensitive to both initial- and final-state nonperturbative effects for a mix of parton flavors. Comparisons of the differences in their transverse single-spin asymmetries have the potential to disentangle the possible effects of strangeness, isospin, or mass. These results can constrain the twist-3 trigluon collinear correlation function as well as the gluon Sivers function.

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