Energy Correlators within Jets in Transversely Polarized Proton-Proton Collisions at โs =200 GeV
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73 NUCLEAR PHYSICS AND RADIATION PHYSICSโ
Engineering topics
Fu, T.
Publications and source records attributed to Fu, T..
Tracking the baryon number with nuclear collisions
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73 NUCLEAR PHYSICS AND RADIATION PHYSICSโ
First Observation of Deuteron-ฮ Correlations at RHIC
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73 NUCLEAR PHYSICS AND RADIATION PHYSICSโ
Measurement of inclusive $J/ฯ$ production in Au+Au collisions at $\sqrt{s_{\textrm{NN}}}$ = 54.4 GeV at STAR
This article presents measurements of inclusive J/ฯ production at midrapidity (|y| < 1.0) in Au+Au collisions at $\sqrt{s_{\textrm{NN}}}$ = 54.4 GeV with the STAR detector at the Relativistic Heavy Ion Collider. A suppression of the J/ฯ yield, quantified using the nuclear modification factors (R AA , R CP ), is observed with respect to the scaled production p + p in collisions. The dependence of R AA on collision centrality and J/ฯ transverse momentum is measured with improved precision compared to previous measurements at 39 and 62.4 GeV, while the centrality dependence of R CP is measured and compared to the same results at 39, 62.4, and 200 GeV. In central collisions, no significant collision energy dependence of R AA is found within uncertainties for collision energies between 17.3 and 200 GeV. Two transport model calculations that include dissociation and regeneration contributions are consistent with the experimental results within uncertainties. Although no significant collision energy dependence of the J/ฯ suppression in high energy heavy-ion collisions up to $\sqrt{s_{\textrm{NN}}}$ = 200 GeV is observed within uncertainties, the newly measured results at 54.4 GeV Au+Au collisions provide additional constraints on theoretical calculations of the hot medium evolution and cold nuclear matter effects.
73 NUCLEAR PHYSICS AND RADIATION PHYSICSโ
Probing late-stage hadronic interactions at high baryon density via $K^{โ0}$ production in the RHIC beam energy scan program
A precision measurement of the $K^{โ0}$ meson yield is reported in Au+Au collisions at $\sqrt{s_{NN}}$ = 7.7, 11.5, 14.6, 19.6, and 27 GeV using the high-statistics data sample collected by the STAR experiment during the Beam Energy Scan II (BES-II) program at RHIC. The transeverse momentum (p T )-integrated yield ratios $\large{(}K^{โ0} + \overline{K^{โ0}}\large{)}/(K^+ + K^{-})$ in central collisions show a suppression relative to peripheral collisions at the (1.7โ3.6) ฯ level, while a thermal model without final-stage rescattering overpredicts this ratio with a deviation of (6.9โ8.2) ฯ. These results indicate a loss of the measured $K^{โ0}$ signal in central collisions due to re-scattering of its hadronic decay products in the hadronic phase. The p T -integrated yield of charged kaons exhibits an approximate scaling with charged-particle multiplicity, independent of collision energy and system size. A similar trend is observed for the short-lived $K^{โ0}$ resonance, although significant deviations emerge at lower energies. At BES energies, the $K^{โ0}/K$ ratio shows stronger suppression than at the highest RHIC and LHC energies within a given multiplicity bin, particularly in central and mid-central collisions. This behavior is consistent with changes in the effective hadronic interaction cross section and is supported by transport model calculations, which indicate dominant mesonโbaryon interactions at lower energies and mesonโmeson interactions at higher energies.
73 NUCLEAR PHYSICS AND RADIATION PHYSICSโ
Measurement of kaon directed flow in Au+Au collisions in the high baryon density region
Rapidity-odd directed flow v 1 measurements are presented for $K^ยฑ$ and $K^0_S$ in Au + Au collisions for $\sqrt{s_{NN}}$ from 3.0 to 3.9 GeV with the STAR experiment. For comparison, v 1 of ฯ ยฑ , protons, and ฮ from the same collisions are also discussed. The mid-rapidity v 1 slope dv 1 /dy| y=0 for protons and ฮ is positive in these collisions. On the other hand, v 1 slope of kaons exhibits a strong dependence: negative at p T < 0.6 GeV/c and positive at higher p T . A similar p T dependence is also evident for the v 1 slope of charged pions. Compared to the spectator-removed calculations in Au+Au collisions at $\sqrt{s_{NN}}$ = 3.0โ3.9 GeV, the JAM model demonstrates a pronounced shift of the v 1 slopes of mesons towards the negative direction. It suggests that the shadowing effect of the spectators plays an important role in the observed kaon anti-flow at low p T in the high baryon density region of non-central collisions.
73 NUCLEAR PHYSICS AND RADIATION PHYSICSโ
Measuring spin correlation between quarks during QCD confinement
The vacuum is now understood to have a rich and complex structure, characterized by fluctuating energy fields and a condensate of virtual quarkโantiquark pairs. The spontaneous breaking of the approximate chiral symmetry, signalled by the nonvanishing quark condensate $\langle$$q\bar{q}$$\rangle$, is dynamically generated through topologically nontrivial gauge configurations such as instantons. The precise mechanism linking the chiral symmetry breaking to the mass generation associated with quark confinement remains a profound open question in quantum chromodynamics (QCD)โthe fundamental theory of strong interaction. High-energy protonโproton collisions could liberate virtual quarkโantiquark pairs from the vacuum that subsequently undergo confinement to form hadrons, whose properties could serve as probes into QCD confinement and the quark condensate. Here we report evidence of spin correlations in $ฮ\bar{ฮ}$ hyperon pairs inherited from spin-correlated strange quarkโantiquark virtual pairs. Measurements by the STAR experiment at the Relativistic Heavy Ion Collider (RHIC) at Brookhaven National Laboratory reveal a relative polarization signal of (18 ยฑ 4)% that links the virtual spin-correlated quark pairs from the QCD vacuum to their final-state hadron counterparts. Crucially, this correlation vanishes when the hyperon pairs are widely separated in angle, consistent with the decoherence of the quantum system. Our findings provide a new experimental model for exploring the dynamics and interplay of quark confinement and entanglement.
73 NUCLEAR PHYSICS AND RADIATION PHYSICSโ
Temperature measurement of Quark-Gluon plasma at different stages
In a Quark-Gluon Plasma (QGP), the fundamental building blocks of matter, quarks and gluons, are under extreme conditions of temperature and density. A QGP could exist in the early stages of the Universe, and in various objects and events in the cosmos. The thermodynamic and hydrodynamic properties of the QGP are described by Quantum Chromodynamics (QCD) and can be studied in heavy-ion collisions. Despite being a key thermodynamic parameter, the QGP temperature is still poorly known. Thermal lepton pairs (e + e โ and ฮผ + ฮผ โ ) are ideal penetrating probes of the true temperature of the emitting source, since their invariant-mass spectra suffer neither from strong final-state interactions nor from blue-shift effects due to rapid expansion. Here we measure the QGP temperature using thermal e+eโ production at the Relativistic Heavy Ion Collider (RHIC). The average temperature from the low-mass region (in-medium ฯ 0 vector-meson dominant) is (2.01 ยฑ 0.23) ร 10 12 K, consistent with the chemical freeze-out temperature from statistical models and the phase transition temperature from Lattice QCD. The average temperature from the intermediate mass region (above the ฯ0 mass, QGP dominant) is significantly higher at (3.25 ยฑ 0.60) ร 10 12 K. This work provides essential experimental thermodynamic measurements to map out the QCD phase diagram and understand the properties of matter under extreme conditions.
73 NUCLEAR PHYSICS AND RADIATION PHYSICSโ
Hyperon global polarization in isobar Ru+Ru and Zr+Zr collisions at $\sqrt{s_{NN}}$ = 200Ge V
The polarization of ฮ, $\overline{ฮ}$, $ฮ$ โ , and $\overline{ฮ}$ + hyperons along the angular momentum of the system has been measured in isobar collisions of Ru+Ru and Zr+Zr at $\sqrt{s_{NN}}$ = 200 GeV with the STAR detector at RHIC. The polarization dependence on collision centrality exhibits an increasing trend in more peripheral collisions. ฮ and $\overline{ฮ}$ polarization dependence on the transverse momentum and pseudorapidity have been investigated, but no significant dependence was observed. The polarizations of ฮ and $\overline{ฮ}$ are found to be consistent with each other, indicating little contribution of the spin-magnetic coupling to the measured polarization. Comparison to previously measured polarization in Au+Au collisions show no obvious system size dependence. The results are qualitatively consistent with hydrodynamic calculations including contributions from shear-induced polarization and thermal vorticity. For the first time in heavy-ion collisions, the dependence of the global polarization on the hyperonโs emission azimuthal angle relative to the second-order event plane has been measured, indicating stronger polarization for the in-plane emitted hyperons at the level of 2.4 ฯ significance in 20โ50 % centrality. The $ฮ$ hyperon polarization measurements via polarization transfer analysis yield finite positive values with 2.9 ฯ significance in 20โ50 % centrality, slightly larger compared to the inclusive ฮ polarization.
73 NUCLEAR PHYSICS AND RADIATION PHYSICSโ
Semi-inclusive direct photon + jet and ๐ 0 + jet correlations measured in ๐ + ๐ and central Au + Au collisions at $\sqrt{s_{NN}}$ = 200GeV
The STAR experiment at RHIC reports new measurements of jet quenching based on the semi- inclusive distribution of charged-particle jets recoiling from direct photon (ฮณ dir ) and neutral pion (ฯ 0 ) triggers in pp and central Au + Au collisions at $\sqrt{s_{NN}}$ = 200 GeV, for triggers in the range 9 < $E$$^{trig}_{T}$ < 20 GeV. The datasets have integrated luminosities of 3.9nb โ1 for Au + Au and 23pb โ1 for ๐๐ collisions. Jets are reconstructed using the anti-๐ ๐ algorithm with resolution parameters ๐ = 0.2 and 0.5. The large uncorrelated jet background in central Au + Au collisions is corrected using a mixed-event approach, which enables precise charged-particle jet measurements at low transverse momentum ๐$^{ch}_{๐,jet}$ and large ๐ . Recoil-jet distributions are reported in the range ๐$^{ch}_{๐,jet}$ < 25 GeV/๐. Comparison of the distributions measured in ๐๐ and Au + Au collisions reveals strong medium-induced jet yield suppression for ๐ = 0.2 with markedly less suppression for ๐ = 0.5. Comparison is also made to theoretical models incorporating jet quenching. Furthermore, these data provide new insight into the mechanisms underlying jet quenching and the angular dependence of medium-induced jet-energy transport and provide new constraints on modeling such effects.
73 NUCLEAR PHYSICS AND RADIATION PHYSICSโ
Light nuclei femtoscopy and baryon interactions in 3 GeV Au+Au collisions at RHIC
We report the measurements of proton-deuteron (๐-๐) and deuteron-deuteron (๐-๐) correlation functions in Au + Au collisions at $\sqrt{s_{NN}}$ = 3 GeV using fixed-target mode with the STAR experiment at the Relativistic Heavy-Ion Collider (RHIC). For the first time, the source size (๐ ๐บ ), scattering length (๐ 0 ), and effective range (๐ 0 ) are extracted from the measured correlation functions with a simultaneous fit. The spin-averaged ๐ 0 for ๐-๐ and ๐-๐ interactions are determined to be -5.28 ยฑ 0.11(stat.) ยฑ 0.82(syst.) fm and -2.62 ยฑ 0.02(stat.) ยฑ0.24(syst.) fm, respectively. The measured ๐-๐ interaction is consistent with theoretical calculations and low energy scattering experiment results, demonstrating the feasibility of extracting interaction parameters using the femtoscopy technique. The reasonable agreement between the experimental data and the calculations from the transport model indicates that deuteron production in these collisions is primarily governed by nucleon coalescence.
73 NUCLEAR PHYSICS AND RADIATION PHYSICSโ
Electric-charge-dependent directed flow splitting of produced quarks in Au+Au collisions
We report directed flow (v 1 ) of multistrange baryons ($ฮ$ and ฮฉ) and improved v 1 data for K โ ,$\overline{p}$, $\overline{ฮ}$, and ฯ in Au+Au collisions at $\sqrt{s_{NN}}$ = 27 and 200 GeV from the STAR experiment at the Relativistic Heavy Ion Collider (RHIC). We focus on particles whose constituent quarks are not transported from the incoming nuclei but instead are produced in the collisions. At intermediate impact parameters, we examine quark coalescence behavior for particle combinations with identical quark content, and search for any departure from this behavior (โsplittingโ) for combinations having non-identical quark content. Under the assumption of quark coalescence for produced quarks, the splitting strength appears to increase with the electric charge difference of the constituent quarks in the combinations, consistent with electromagnetic effect expectations.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDSโ
The Compensating Common-Gate Frontend Circuit Used as Current Source Receiver
A very low power frontend circuit using the compensating common-gate scheme is described. It combines features of the regular common-gate topology and the trans-impedance amplifier (TIA) schemes allowing designers to achieve low input impedance and sufficient bandwidth with small power consumption. It can be used as an interface between detectors and the pseudo-thyristors we developed to complete a full frontend signal chain. Simulation shows that in a 65 nm process, it is possible to achieve an input impedance <1K Ohms allowing a charge detection <6fC with 3pF parasitic capacitance, using static power below 20 micro-Watts/channel.
Fu, T.โ
The CMOS Pseudo-Thyristor: a zero-static current discriminator circuit
We report a very low power discriminator circuit for pixelized detectors, called the Pseudo-Thyristor is described in this document. It is a positive feedback topology using regular PMOS and NMOS field-effect transistors (FET's) with zero static current. When a small charge is injected into the circuit, it flips rapidly due to the positive feedback and outputs a logic transition for further digitization. Simulation shows that in a 65 nm process, it is possible to achieve a detecting threshold below 5 fC while maintain the average power consumption below 10 micro-Watts when the hit occupancy is <10% for 40 MHz operation.
72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDSโ
Opportunities for Joint WaterโEnergy Management: Sensitivity of the 2010 Western U.S. Electricity Grid Operations to Climate Oscillations
The 2016 SECURE Water Act reportโs natural water availability benchmark, combined with the 2010 level of water demand from an integrated assessment model, is used as input to drive a large-scale water management model. The regulated flow at hydropower plants and thermoelectric plants in the Western U.S. electricity grid (WECC) is translated into potential hydropower generation and generation capacity constraints. The impact on reliability (unserved energy, reserve margin) and cost (production cost, carbon emissions) of water constraints on 2010-level WECC power system operations is assessed using an electricity production cost model (PCM). Use of the PCM reveals the changes in generation dispatch that reflect the inter-regional interdependencies in water-constrained generation and the ability to use other generation resources to meet all electricity loads in the WECC. August grid operational benchmarks show a range of sensitivity in production cost (-8 to +11%) and carbon emissions (-7 to 11%). The reference reserve margin threshold of 15% above peak load is maintained in the scenarios analyzed, but in 5 out of 55 years unserved energy is observed when normal operations are maintained. There is 1 chance in 10 that a year will demonstrate unserved energy in August, which defines the systemโs historical performance threshold to support impact, vulnerability, and adaptation analysis. For seasonal and longer term planning, i.e., multi-year drought, we demonstrate how the Water Scarcity Grid Impact Factor and climate oscillations (ENSO, PDO) can be used to plan for joint water-electricity management to maintain grid reliability.
adaptationโ
Evaluation of Boundary Dam spillway using an Autonomous Sensor Fish Device
Not Available
Deng, Z. D.โ
Comparing the survival rate of juvenile Chinook salmon migrating through hydropower systems using injectable and surgical acoustic transmitters
Acoustic telemetry is one of the primary technologies for studying the behavior and survival of fishes throughout the world. The size and performance of the transmitters is still the key limiting factor despite that considerable effort has been expended to understand the biological effects of implantation of acoustic transmitters in yearling and subyearling Chinook salmon. The newly developed injectable transmitter is the first active acoustic tag that can be implanted via injection instead of surgery. It also lasts more than four times longer than the commercially-available transmitters. A two-part field study was conducted to evaluate the performance of the injectable transmitter and its effect on the survival of implanted fish. The injectable transmitter performed well and similarly to the other commercially-available transmitters tested. Snake River subyearling Chinook salmon smolts implanted with the injectable tag had a higher survival probability from release to each of 11 downstream detection arrays than concurrent releases of fish surgically implanted with commercially-available tags. In addition, reach-specific survival estimates were significantly higher for the injectable group in three of the eleven reaches examined. Overall, the injectable group had a 0.263 (SE = 0.017) survival probability over the entire 500 km study area compared to 0.199 (0.012) for the surgically implanted group. The differences in survival may have been caused by warm water temperatures and higher rates of infection experienced by the surgically implanted group due to the presence of sutures acting as an attachment site for pathogens. The reduction in size and ability to implant the new transmitter via injection has further reduced the tag or tagging effect bias associated with studying small fishes. As a result, the information gathered with this new technology is helping minimize the impact of dams on fish, leading to more environmentally sustainable energy systems.
13 HYDRO ENERGYโ