Jet Yield Research Articles

Measurements of jet quenching using semi-inclusive hadron+jet distributions in pp and central Pb-Pb collisions at sNN=5.02 TeV

The ALICE Collaboration reports measurements of the semi-inclusive distribution of charged-particle jets recoiling from a high transverse momentum (high pT) charged hadron, in pp and central Pb-Pb collisions at center-of-mass energy per nucleon–nucleon collision sNN=5.02 TeV. The large uncorrelated background in central Pb-Pb collisions is corrected using a data-driven statistical approach which enables precise measurement of recoil jet distributions over a broad range in pT,chjet and jet resolution parameter R. Recoil jet yields are reported for R=0.2, 0.4, and 0.5 in the range 7<pT,chjet<140 GeV/c and π/2<Δφ<π, where Δφ is the azimuthal angular separation between hadron trigger and recoil jet. The low-pT,chjet reach of the measurement explores unique phase space for studying jet quenching, the interaction of jets with the quark–gluon plasma generated in high-energy nuclear collisions. Comparison of pT,chjet distributions from pp and central Pb-Pb collisions probes medium-induced jet energy loss and intra-jet broadening, while comparison of their acoplanarity distributions explores in-medium jet scattering and medium response. The measurements are compared to theoretical calculations incorporating jet quenching. ©2024 CERN, for the ALICE Collaboration 2024 CERN

Observation of Medium-Induced Yield Enhancement and Acoplanarity Broadening of Low-p_{T} Jets from Measurements in pp and Central Pb-Pb Collisions at sqrt[s_{NN}]=5.02 TeV.

The ALICE Collaboration reports the measurement of semi-inclusive distributions of charged-particle jets recoiling from a high transverse momentum (high p_{T}) hadron trigger in proton-proton and central Pb-Pb collisions at sqrt[s_{NN}]=5.02 TeV. A data-driven statistical method is used to mitigate the large uncorrelated background in central Pb-Pb collisions. Recoil jet distributions are reported for jet resolution parameter R=0.2, 0.4, and 0.5 in the range 7<p_{T,jet}<140 GeV/c and trigger-recoil jet azimuthal separation π/2<Δφ<π. The measurements exhibit a marked medium-induced jet yield enhancement at low p_{T} and at large azimuthal deviation from Δφ∼π. The enhancement is characterized by its dependence on Δφ, which has a slope that differs from zero by 4.7σ. Comparisons to model calculations incorporating different formulations of jet quenching are reported. These comparisons indicate that the observed yield enhancement arises from the response of the QGP medium to jet propagation.

Modification of charged-particle jets in event-shape engineered Pb–Pb collisions at [formula omitted] TeV

Charged-particle jet yields have been measured in semicentral Pb–Pb collisions at center-of-mass energy per nucleon–nucleon collision sNN=5.02 TeV with the ALICE detector at the LHC. These yields are reported as a function of the jet transverse momentum, and further classified by their angle with respect to the event plane and the event shape, characterized by ellipticity, in an effort to study the path-length dependence of jet quenching. Jets were reconstructed at midrapidity from charged-particle tracks using the anti-kT algorithm with resolution parameters R = 0.2 and 0.4, with event-plane angle and event-shape values determined using information from forward scintillating detectors. The results presented in this letter show that, in semicentral Pb–Pb collisions, there is no significant difference between jet yields in predominantly isotropic and elliptical events. However, out-of-plane jets are observed to be more suppressed than in-plane jets. Further, this relative suppression is greater for low transverse momentum (< 50 GeV/c) R = 0.2 jets produced in elliptical events, with out-of-plane to in-plane jet-yield ratios varying up to 5.2σ between different event-shape classes. These results agree with previous studies indicating that jets experience azimuthally anisotropic suppression when traversing the QGP medium, and can provide additional constraints on the path-length dependence of jet energy loss.

New measurements of inclusive jet suppression and jet ν2 in Pb–Pb collisions at √SNN = 5.02 TeV with ALICE

We report measurements of the inclusive charged-particle jet yield in central Pb–Pb collisions at √SNN = 5.02 TeV. Uncorrelated background is suppressed by a novel mixed-event technique, enabling extension of the jet RAA measurement down to pT = 13.5 GeV/c, with kinematic overlap with RHIC jet measurements. We also present measurements of inclusive charged-particle jet v2 in semi-central Pb–Pb collisions at √SNN = 5.02 TeV, and azimuthal dependence of jet yield suppression for event topologies selected using eventshape engineering.

Jet energy redistribution and broadening using hadron+jet measurements in pp and Pb–Pb collisions with ALICE

In this contribution we present measurements of the semi-inclusive distributions of charged jets recoiling from a trigger hadron (hadron+jet) in pp and Pb–Pb collisions, which provide unique probes of medium-induced modification of jet production. We observe that the jet yield at low pT and at large azimuthal angle between the trigger hadron and jet is significantly enhanced in Pb–Pb collisions with respect to pp collisions, which we interpret through comparisons to model calculations.

The gradient fabrication and optimization of metal-acid bifunctional catalysts for the hydrogenation of n-C16 to produce bio-jet fuel component

In the two-step hydrogenation of oil to produce bio-jet fuel, the yield of bio-jet fuel is determined by the hydrotreatment of long-chain alkanes over a metal–acid bifunctional catalyst. A strategy that the catalyst with better isomerization is conductive to the hydrotreatment of long-chain alkanes to produce jet fuel component is proposed. Based on the hollow silicon sphere (HSS), catalysts with different acid strength, diffusion performance, and intimacy between Pt and acid bifunctional sites were designed to gradually optimize the isomerization performance. After the gradient optimization of weak acid, strong diffusion performance, and minor-nanoscale intimacy between Pt and acid sites, the gradient catalysts exhibited a constantly improving yield of isomer product and jet fuel component. The yolk-shell WHSS@Pt catalyst with three levels of simultaneous optimization performed the favorable yield of jet fuel component (37 wt.%), which can be attributed to the combination of weak acid, strong diffusion performance, and minor-nanoscale intimacy between bifunctional sites that are beneficial to the isomerization of long-chain alkanes.

Measurement of Medium-induced Modification of Jet Yield and Acoplanarity Using Semi-inclusive \(\gamma _{\mathrm {dir}}+\)jet and \(\pi ^{0}+\)jet Distributions in \(p+p\) and Central Au\(+\)Au Collisions at \(\sqrt {s_{NN}} = 200\) GeV by STAR

Measurement of Medium-induced Modification of Jet Yield and Acoplanarity Using Semi-inclusive \(\gamma _{\mathrm {dir}}+\)jet and \(\pi ^{0}+\)jet Distributions in \(p+p\) and Central Au\(+\)Au Collisions at \(\sqrt {s_{NN}} = 200\) GeV by STAR

Catalytic co‐pyrolysis of low‐density polyethylene (LDPE) and lignin for jet fuel range hydrocarbons over activated carbon catalyst

The catalytic conversion of low-density polyethylene (LDPE) and lignin over activated carbon into jet fuel range hydrocarbons was studied. A fixed bed furnace was used to investigate the impacts of temperature, LDPE to lignin ratio, and catalyst to feedstock ratio on the composition of bio-oils, and up to 100 area% jet fuel range hydrocarbons can be acquired from the catalytic co-pyrolysis of LDPE and lignin. The results showed that the activated carbon has an excellent catalytic performance to convert LDPE and lignin into jet fuel range hydrocarbons. The properties of activated carbon catalyst were characterized by nitrogen gas adsorption, Fourier transform infrared spectrometer, and scanning electron microscope. There is a synergistic effect between the higher pyrolysis temperature and the acid sites of activated carbon on the dissociation and conversion of alkanes to form the aromatics. In addition, the yield of jet fuel range hydrocarbons could be enhanced by the synergistic effect of LDPE on the catalytic conversion of lignin. This work provided an environment friendly, economical, convenient, simple, and effective route to acquire jet fuel range hydrocarbons from daily waste plastics and biomass.

Multiplicity dependence of charged-particle jet production in pp collisions at mathbf {sqrt{s}}=mathbf {13~TeV}

The multiplicity dependence of jet production in pp collisions at the centre-of-mass energy of sqrt{s} = 13 {mathrm {TeV}} is studied for the first time. Jets are reconstructed from charged particles using the anti-k_mathrm {T} algorithm with resolution parameters R varying from 0.2 to 0.7. The jets are measured in the pseudorapidity range |eta _{mathrm{jet}}|< 0.9-R and in the transverse momentum range 5<p_mathrm {T,jet}^{mathrm{ch}}<140 {mathrm {GeV}}/c. The multiplicity intervals are categorised by the ALICE forward detector V0. The p_{mathrm T} differential cross section of charged-particle jets are compared to leading order (LO) and next-to-leading order (NLO) perturbative quantum chromodynamics (pQCD) calculations. It is found that the data are better described by the NLO calculation, although the NLO prediction overestimates the jet cross section below 20 {mathrm {GeV}}/c. The cross section ratios for different R are also measured and compared to model calculations. These measurements provide insights into the angular dependence of jet fragmentation. The jet yield increases with increasing self-normalised charged-particle multiplicity. This increase shows only a weak dependence on jet transverse momentum and resolution parameter at the highest multiplicity. While such behaviour is qualitatively described by the present version of PYTHIA, quantitative description may require implementing new mechanisms for multi-particle production in hadronic collisions.

Cascade hydrogenation of n-C16 to produce jet fuel over tandem catalysts of modified ZSM-22

ZSM-22 with one-dimensional straight channels and suitable acid properties is widely applied in the selective hydrocracking of long-chain alkanes to produce middle distillate. In this work, the tandem catalysts with two kinds of modified ZSM-22 were employed in series to optimize the distribution of the product in the hydrotreatment of n-C16 to produce jet fuel. The yield of linear alkanes with high carbon numbers was enhanced over the upstream catalyst bed of Pt/L-HZSM-22 with shielded external acid sites while the isomerization with less further cracking occurred over the downstream catalyst bed of Pt/Me-HZSM-22 with introduced mesopores. The tandem catalysts can combine the ability of Pt/L-HZSM-22 to produce heavy n-alkanes and the stronger isomerization performance of Pt/Me-HZSM-22. The highest yield of jet fuel (∼23 wt.%) can be obtained over the tandem catalysts instead of any individual catalyst. The strategy of the tandem zeolite has been initially verified and proposed to broaden the investigation perspectives of the oil refinery.

Measurement of inclusive charged-particle jet production in Au + Au collisions at sNN=200 GeV

The STAR Collaboration at the Relativistic Heavy Ion Collider reports the first measurement of inclusive jet production in peripheral and central Au+Au collisions at $\sqrt{s_{NN}}$=200 GeV. Jets are reconstructed with the anti-k$_{T}$ algorithm using charged tracks with pseudorapidity $|\eta|<1.0$ and transverse momentum $0.2<p_{T,jet}^{ch}<30$ GeV/$c$, with jet resolution parameter $R$=0.2, 0.3, and 0.4. The large background yield uncorrelated with the jet signal is observed to be dominated by statistical phase space, consistent with a previous coincidence measurement. This background is suppressed by requiring a high-transverse-momentum (high-$p_T$) leading hadron in accepted jet candidates. The bias imposed by this requirement is assessed, and the $p_T$ region in which the bias is small is identified. Inclusive charged-particle jet distributions are reported in peripheral and central Au+Au collisions for $5<p_{T,jet}^{ch}<25$ GeV/$c$ and $5<p_{T,jet}^{ch}<30$ GeV/$c$, respectively. The charged-particle jet inclusive yield is suppressed for central Au+Au collisions, compared to both the peripheral Au+Au yield from this measurement and to the $pp$ yield calculated using the PYTHIA event generator. The magnitude of the suppression is consistent with that of inclusive hadron production at high $p_T$, and that of semi-inclusive recoil jet yield when expressed in terms of energy loss due to medium-induced energy transport. Comparison of inclusive charged-particle jet yields for different values of $R$ exhibits no significant evidence for medium-induced broadening of the transverse jet profile for $R<0.4$ in central Au+Au collisions. The measured distributions are consistent with theoretical model calculations that incorporate jet quenching.

Supported heteropolyacids catalysts for the selective hydrocracking and isomerization of n-C16 to produce jet fuel

In the process of two-stage hydrogenation from bio-oil to jet fuel, the selective cracking and isomerization of long-chain alkanes is the key step. The n-C16 was used as the model reactant to produce jet fuel and the supported metal-acid bifunctional HPA/MCM-41 catalyst was prepared. The acid strength and amount of the catalyst could be modified by adjusting the type (HPW, HSiW, HPMo) and loading of HPA. The highest yield of jet fuel (≈ 20 wt.%) was obtained over Pt/40 wt.% HPMo/MCM-41 (WHSV = 1 h−1), which possessed more B acid sites but few strong acid sites. Besides, it possesses a higher yield than the previous work and favorable catalytic stability of 100 h. It was further explored that the reaction path net of hydrocracking and isomerization of n-C16 was a cascade reaction from n-C16 to single-branched isomer, further to multi-branched isomer and then to the cracking product.

Measurements of inclusive jet spectra in pp and central Pb-Pb collisions at sNN=5.02TeV

This article reports measurements of the $p_{\rm{T}}$-differential inclusive jet cross-section in pp collisions at $\sqrt{s}$ = 5.02 TeV and the $p_{\rm{T}}$-differential inclusive jet yield in Pb-Pb 0-10% central collisions at $\sqrt{s_{\rm{NN}}}$ = 5.02 TeV. Jets were reconstructed at mid-rapidity with the ALICE tracking detectors and electromagnetic calorimeter using the anti-$k_{\rm{T}}$ algorithm. For pp collisions, we report jet cross-sections for jet resolution parameters $R=0.1-0.6$ over the range $20<p_{\rm{T,jet}}<140$ GeV/$c$, as well as the jet cross-section ratios of different $R$, and comparisons to two next-to-leading-order (NLO)-based theoretical predictions. For Pb-Pb collisions, we report the $R=0.2$ and $R=0.4$ jet spectra for $40<p_{\rm{T,jet}}<140$ GeV/$c$ and $60<p_{\rm{T,jet}}<140$ GeV/$c$, respectively. The scaled ratio of jet yields observed in Pb-Pb to pp collisions, $R_{\rm{AA}}$, is constructed, and exhibits strong jet quenching and a clear $p_{\rm{T}}$-dependence for $R=0.2$. No significant $R$-dependence of the jet $R_{\rm{AA}}$ is observed within the uncertainties of the measurement. These results are compared to several theoretical predictions.

Integration of Heterogeneous Acid and Base Catalysis for Clean Synthesis of Jet‐Fuel Precursor from Carbohydrates

AbstractC12 branched alkane fuel precursor was produced from carbohydrates using an efficient integrated solid acid and base catalysis approach involving: i) isomerisation‐dehydration of carbohydrates to 5‐(hydroxymethyl)furfural (HMF) over solid acid catalyst having both Lewis and Brónsted sites) in a biphasic MIBK (methylisobutylketone): water + DMSO solvent system and ii) Claisen‐Schmidt condensation of crude HMF with MIBK over solid base catalyst. Initially, high yield of jet fuel precursor, (E)‐1‐(5‐(hydroxymethyl)furan‐2‐yl)‐5‐methylhex‐1‐en‐3‐one from pure HMF and MIBK was achieved over basic CaMgAl(231) catalyst. The glucose dehydration to HMF was optimized in biphasic MIBK: H2O‐NaCl: DMSO (8:1.5:0.5; v/v/v) system, with complete glucose conversion and 42% HMF yield over Zr‐Mont possessing both Lewis and Brønsted acid sites. In an integrated dehydration + Claisen‐Schmidt condensation sequence, Zr‐Mont catalyst was filtered off and the crude HMF with MIBK underwent Claisen‐Schmidt condensation over CaMgAl(231) catalyst. The overall 32% yield of Claisen‐Schmidt condensation product was achieved from glucose. MIBK acting also as a product extractant, could be recovered upto 80%.

Synthesis of Diesel and Jet Fuel Range Cycloalkanes with Cyclopentanone and Furfural

Diesel and jet fuel range cycloalkanes were obtained in ~84.8% overall carbon yield with cyclopentanone and furfural, which can be produced from hemicellulose. Firstly, 2,5-bis(furan-2-ylmethyl)-cyclopentanone was prepared by the aldol condensation/hydrogenation reaction of cyclopentanone and furfural under solid base and selective hydrogenation catalyst. Over the optimized catalyst (Pd/C-CaO), 98.5% carbon yield of 2,5-bis(furan-2-ylmethyl)-cyclopentanone was acquired at 423 K. Subsequently, the 2,5-bis(furan-2-ylmethyl)-cyclopentanone was further hydrodeoxygenated over the M/H-ZSM-5(Pd, Pt and Ru) catalyst. Overall, 86.1% carbon yield of diesel and jet fuel range cycloalkanes was gained over the Pd/H-ZSM-5 catalyst under solvent-free conditions. The cycloalkane mixture obtained in this work has a high density (0.82 g mL−1) and a low freezing point (241.7 K). Therefore, it can be mixed into diesel and jet fuel to increase their volumetric heat values or payloads.

Hexadecane hydrocracking for production of jet fuels from renewable diesel over proton and metal modified H-Beta zeolites

Hydrocracking of hexadecane to produce jet fuel components was investigated over proton and metal modified Beta zeolites with different acidity. They were characterized by a range of physico-chemical methods. The initial catalyst screening was performed at 210 °C under 40 bar hydrogen showing that the most promising catalysts were 2.5 wt% Pt-H-Beta-25 and 2.5 wt% Ru-H-Beta-300, which were also tested at 240 °C under 45 bar hydrogen. The results revealed that the yield of jet fuel components was maximally 27% over 2.5 wt% Pt-H-Beta-25. This catalyst gave, however, only 55% mass balance closure to the liquid phase products, while a mildly acidic 2.5 wt% Ru-H-Beta-300 afforded 24% yield of the jet fuel components and 89% liquid mass balance closure.

Study of jet-medium interactions using jet shape observables in heavy ion collisions at LHC energies with JEWEL

Based on a perturbative quantum chromodynamics inspired dynamical model of jet-medium interactions, Jewel, we have studied possible modifications to inclusive jet yields and a set of jet shape observables, namely, the fragmentation functions and radial momentum distributions when jets propagate through a deconfined partonic medium created in collisions of heavy nuclei at Large Hadron Collider (LHC) energies. Jets are reconstructed with anti-kT algorithm in the pseudorapidity range for resolution parameter R = 0.2, 0.3 and 0.4. For background subtraction, a Jewel-compatible 4-Momenta subtraction technique (4MomSub) has been used. The modification of inclusive jet-yields in Pb–Pb collisions relative to proton–proton interactions, quantified by , are seen to be in reasonable agreement with ALICE, ATLAS and CMS data over a broad transverse momentum range. Jewel is able to capture the qualitative features of the modifications to the fragmentation functions and radial momentum distributions in data but not always quantitatively. This quantitative discrepancy may be related to the simplified treatment of recoil partons in the background model and partly due to background subtraction procedure itself. Nevertheless, observed modifications to jet shape observables in Jewel corroborates the fact that in-medium fragmentation is harder and more collimated than the fragmentation in vacuum. We further observe that these modifications depend on the transverse momentum of jets and it seems that medium resolves the core structure of low momentum jets below 100 GeV c–1 at LHC energies.

PHENIX results on jet modification with π0- and photon-triggered two particle correlations in p+p, p(d)+Au, and Au+Au collisions

As a colorless probe, direct photons balance the pT of the away-side jet at leading order. Direct photon-hadron correlations are thus an excellent probe for nuclear structure and QCD effects, including parton energy loss in the Quark-Gluon Plasma. PHENIX has measured π0 and direct photon-triggered two-particle azimuthal correlations in a variety of collision systems ranging from p+p to Au+Au at 200 GeV. In p+Au and d+Au collisions, no modification of the per-trigger jet yield or away-side correlation width compared to p+p collisions is observed for direct photon triggered correlations while an increase in the away-side width for π0 triggered correlations in p+Au has been measured. In Au+Au collisions, direct photons have been identified statistically as well as using an isolation cut. Combining data sets from different collision systems allows us to quantify the transition from suppression at high zT(pT,h/pT,γ) to the enhancement of low zT particles relative to p+p, and to study this transition as a function of trigger pT.

Recent results on hard probes with ALICE and STAR

This paper reviews recent experimental results on hard probes in heavy-ion collisions from the ALICE and STAR Collaboration. These studies include various observables characterizing jet properties like nuclear modification factors, recoil jet yields, di-jet and photon-jet energy imbalance, and the observables characterizing jet properties like jet fragmentation function and jet shapes; and measurements of high-pT charged hadrons from jet fragmentation and triggered particle correlations will be highlighted.

Measurement of photon–jet transverse momentum correlations in 5.02 TeV Pb + Pb and pp collisions with ATLAS

Jets created in association with a photon can be used as a calibrated probe to study energy loss in the medium created in nuclear collisions. Measurements of the transverse momentum balance between isolated photons and inclusive jets are presented using integrated luminosities of 0.49 nb−1 of Pb + Pb collision data at sNN=5.02 TeV and 25 pb−1 of pp collision data at s=5.02 TeV recorded with the ATLAS detector at the LHC. Photons with transverse momentum 63.1<pTγ<200 GeV and |ηγ|<2.37 are paired with all jets in the event that have pTjet>31.6 GeV and pseudorapidity |ηjet|<2.8. The transverse momentum balance given by the jet-to-photon pT ratio, xJγ, is measured for pairs with azimuthal opening angle Δϕ>7π/8. Distributions of the per-photon jet yield as a function of xJγ, (1/Nγ)(dN/dxJγ), are corrected for detector effects via a two-dimensional unfolding procedure and reported at the particle level. In pp collisions, the distributions are well described by Monte Carlo event generators. In Pb + Pb collisions, the xJγ distribution is modified from that observed in pp collisions with increasing centrality, consistent with the picture of parton energy loss in the hot nuclear medium. The data are compared with a suite of energy-loss models and calculations.