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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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All sourcesNASA NTRSDOE OSTI
DOE OSTI2025

Test Results of the LQXFA/B02 and LQXFA/B03 Cryo-Assemblies for the High Luminosity LHC Upgrade

Here, the US High-Luminosity LHC Accelerator Upgrade Project (AUP) is responsible for delivering cryo-assemblies for the Q1/Q3 quadrupole optical components of the High Luminosity LHC upgrade at CERN. Total of 10 cryo-assemblies containing two Nb3Sn quadrupole magnets per cold mass will be delivered within this program. After the successful test of the first pre-series cryo-assembly in 2023, two more cryo-assemblies were tested at Fermilab's horizontal test facility. Production overview and the test results of the LQXFA/B02 and LQXFA/B03 cryo-assemblies are summarized in this paper. After the first test, to increase the capability of the horizontal test facility, various improvements have been made. These improvements are also described in this paper.

Chlachidze, Guram [Fermi National Accelerator Labo↗
DOE OSTI2017

Higgs boson decay to light jets at the LHC

We study here the Higgs boson $(h)$ decay to two light jets at the 14 TeV High-Luminosity-LHC (HL-LHC), where a light jet ($j$) represents any non-flavor tagged jet from the observational point of view. The decay mode $h\to gg$ is chosen as the benchmark since it is the dominant channel in the Standard Model (SM), but the bound obtained is further applicable to the light quarks $(j=u,d,s)$. We also estimate the achievable bounds on the decay branching fractions through the associated production $Vh\ (V=W^\pm,Z)$. Events of the Higgs boson decaying into heavy (tagged) or light (un-tagged) jets are correlatively analyzed. We find that with 3000 fb$^{-1}$ data at the HL-LHC, we should expect approximately $1\sigma$ statistical significance on the SM $Vh(gg)$ signal in this channel. This corresponds to a reachable upper bound ${\rm BR}(h\to jj) \leq 4~ {\rm BR}^{SM}(h\to gg)$ at $95\%$ confidence level. A consistency fit also leads to an upper bound ${\rm BR}(h\to cc) < 15~ {\rm BR}^{SM}(h\to cc)$ at $95\%$ confidence level. The estimated bound may be further strengthened by adopting multiple variable analyses, or adding other production channels.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2017

Hadron Structure Studies with a Fixed-Target Experiment at the LHC - AFTER@LHC

I will illustrate some of the opportunities for hadron structure studies at a future multi-purpose fixed-target experiment at the LHC. The proton beams at the LHC allow for the most energetic fixed-target experiments ever performed, opening new kinematic windows on hadron and nuclear physics which integrate the knowledge available from collider experiments (in particular RHIC and EIC).?? I will discuss how AFTER@LHC will shed light on the proton-spin puzzle by investigating Transverse-Momentum Dependent parton distribution functions (TMDs). Unpolarized proton-proton collisions allow to access unpolarized quark and gluon TMDs, the Boer-Mulders quark TMD and the distribution of linearly polarized gluons in unpolarized protons. Looking at polarized targets, single-transverse-spin asymmetries (STSAs) for processes such as Drell-Yan lepton-pair and quarkonium production will allow measurements of polarized TMDs for quarks and gluons, such as the Sivers functions. Moreover, I will show how, thanks to the boost of the fixed target mode, the acceptance of detectors like LHCb and ALICE in the fixed-target mode allows to analyze processes which are sensitive to the intrinsic charm content of the proton. In particular, I will address some aspects of D meson, charm + photon as well as J/psi-pair production.

Signori, Andrea↗
DOE OSTI2018

Physics opportunities with a fixed target experiment at the LHC (AFTER@LHC)

By extracting the beam with a bent crystal or by using an internal gas target, the multi-TeV proton and lead LHC beams allow one to perform the most energetic fixed-target experiments (AFTER@LHC) and to study p+p and p+A collisions at \sqrt{s_NN}=115 GeV and Pb+p and Pb+A collisions at \sqrt{s_NN}=72 GeV. Such studies would address open questions in the domain of the nucleon and nucleus partonic structure at high-x, quark-gluon plasma and, by using longitudinally or transversally polarised targets, spin physics. In this paper, we discuss the physics opportunities of a fixed-target experiment at the LHC and we report on the possible technical implementations of a high-luminosity experiment. We finally present feasibility studies for Drell-Yan, open heavy-flavour and quarkonium production, with an emphasis on high-x and spin physics.

Hadjidakis, Cynthia↗
DOE OSTI2015

Halo-independent tests of dark matter direct detection signals: local DM density, LHC, and thermal freeze-out

From an assumed signal in a Dark Matter (DM) direct detection experiment a lower bound on the product of the DM-nucleon scattering cross section and the local DM density is derived, which is independent of the local DM velocity distribution. This can be combined with astrophysical determinations of the local DM density. Within a given particle physics model the bound also allows a robust comparison of a direct detection signal with limits from the LHC. Furthermore, the bound can be used to formulate a condition which has to be fulfilled if the particle responsible for the direct detection signal is a thermal relic, regardless of whether it constitutes all DM or only part of it. We illustrate the arguments by adopting a simplified DM model with a Z{sup ′} mediator and assuming a signal in a future xenon direct detection experiment.

43 PARTICLE ACCELERATORS↗
DOE OSTI2015

The eejj excess signal at the LHC and constraints on leptogenesis

We review the non-supersymmetric (Extended) Left-Right Symmetric Models (LRSM) and low energy E{sub 6}-based models to investigate if they can explain both the recently detected excess eejj signal at CMS and leptogenesis. The eejj excess can be explained from the decay of the right-handed gauge bosons (W{sub R}) with mass ∼ TeV in certain variants of the LRSM (with g{sub L}≠g{sub R}). However such scenarios can not accommodate high-scale leptogenesis. Other attempts have been made to explain leptogenesis while keeping the W{sub R} mass almost within the reach of the LHC by considering the resonant leptogenesis scenario in the context of the LRSM for relatively large Yukawa couplings. However, certain lepton number violating scattering processes involving the right-handed Higgs triplet and the right-handed neutrinos can stay in equilibrium till the electroweak phase transition and can washout the lepton asymmetry generated in the resonant leptogenesis scenario for mass range of W{sub R} as indicated by the CMS excess signal. Thus in such a scenario one needs to invoke post-sphaleron baryogenesis to explain the observed baryon asymmetry of the universe. Next, we consider three effective low energy subgroups of the superstring inspired E{sub 6} model having a number of additional exotic fermions which provides a rich phenomenology to be explored. We however find that these three effective low energy subgroups of E{sub 6} too cannot explain both the eejj excess signal and leptogenesis simultaneously.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

The HL-LHC Low-β Quadrupole Magnet MQXF: From Short Models to Long Prototypes

Among the components to be upgraded in LHC interaction regions for the HiLumi-LHC projects are the inner triplet (or low-β) quadrupole magnets, denoted as Q1, Q2a, Q2b, and Q3. Here, the new quadrupole magnets, called MQXF, are based on Nb3Sn superconducting magnet technology and operate at a gradient of 132.6 T/m, with a conductor peak field of 11.4 T. Q1 and Q3 are composed of magnets (called MQXFA) fabricated by the U.S. Accelerator Upgrade Project (AUP), with a magnetic length of 4.2 m. Q2a and Q2b consist of magnets (called MQXFB) fabricated by CERN, with a magnetic length of 7.15 m. After a series of short models, constructed in close collaboration by the US and CERN, the development program is now entering in the prototyping phase, with CERN on one side and BNL, FNAL, and LBNL on the other side assembling and testing their first long magnets We provide in this paper a description of the status of the MQXF program, with a summary of the short model test results, including quench performance, and mechanics, and an update on the fabrication, assembly, and test of the long prototypes.

43 PARTICLE ACCELERATORS↗
DOE OSTI2016

U.S. Involvement in the LHC

The demise of the SSC in the U.S. created an upheaval in the U.S. High energy physics (HEP) community. The subsequent redirection of HEP efforts to the CERN Large Hadron Collider (LHC) can perhaps be seen as informing on possible future paths for worldwide collaboration on future HEP megaprojects

Green, Dan↗
DOE OSTI2020

Testing Yukawa unification at LHC Run-3 and HL-LHC

We explore t-b-τ Yukawa unification (YU) in a supersymmetric SU(4) c × SU(2) L × SU(2) R model without imposing a discrete left-right (L-R) symmetry. A number of interesting solutions that are compatible with t-b-τ YU, LSP neutralino dark matter (DM), and LHC and other experimental constraints are identified. In particular, they include gluino-neutralino and stau-neutralino coannihilation scenarios, where the NLSP gluino mass can range from 1–3 TeV. Higgsino-like dark matter solutions are also identified for which gluino masses can approach 5 TeV or so. This scenario will be tested at LHC Run-3 and its future upgrades.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2015

Measurement of charged-particle spectra in Pb+Pb collisions at \( \sqrt{s_{\mathrm{NN}}}=2.76 \) TeV with the ATLAS detector at the LHC

Charged-particle spectra obtained in Pb+Pb interactions at \( \sqrt{s_{\mathrm{NN}}}=2.76 \) TeV and pp interactions at \( \sqrt{s_{\mathrm{NN}}}=2.76 \) TeV with the ATLAS detector at the LHC are presented, using data with integrated luminosities of 0.15 nb⁻¹ and 4.2 pb⁻¹, respectively, in a wide transverse momentum (0.5 < p T < 150 GeV) and pseudorapidity (|η| < 2) range. For Pb+Pb collisions, the spectra are presented as a function of collision centrality, which is determined by the response of the forward calorimeters located on both sides of the interaction point. The nuclear modification factors R AA and R CP are presented in detail as a function of centrality, p T and η. They show a distinct p T -dependence with a pronounced minimum at about 7 GeV. Above 60 GeV, R AA is consistent with a plateau at a centrality-dependent value, within the uncertainties. The value is 0.55 ± 0.01(stat.) ± 0.04(syst.) in the most central collisions. The R AA distribution is consistent with flat |η| dependence over the whole transverse momentum range in all centrality classes.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2019

A fixed-target programme at the LHC for heavy-ion, hadron, spin and astroparticle physics: AFTER@LHC

Thanks to its multi-TeV LHC proton and lead beams, the LHC complex allows one to perform the most energetic fixed-target experiments ever and to study with high precision pp, pd and pA collisions at √ s NN = 115 GeV and Pbp and PbA collisions at √ s NN = 72 GeV. In conclusion we present a selection of feasibility studies for the production of quarkonia, open heavy-flavor mesons as well as light-flavor hadrons in pA and PbA collisions using the LHCb and ALICE detectors in a fixed-target mode.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Ultraperipheral Collisions at RHIC and the LHC

The current status of ultraperipheral measurements in heavy ion collisions is discussed, with an emphasis on what is learned from one photon (photonuclear) and two photon (γ+γ) processes. Furthermore, the interpretation of recent data on “nonUPC” events, in which electromagnetic processes occur simultaneously with hadronic ones, is also discussed. Results from the LHC (ALICE, ATLAS, CMS, and LHCb) and the STAR experiment at RHIC are discussed.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2017

Performance of the ATLAS Transition Radiation Tracker in Run 1 of the LHC: tracker properties

The tracking performance parameters of the ATLAS Transition Radiation Tracker (TRT) as part of the ATLAS inner detector are described in this paper for different data-taking conditions in proton-proton, proton-lead and lead-lead collisions at the Large Hadron Collider (LHC). The performance is studied using data collected during the first period of LHC operation (Run 1) and is compared with Monte Carlo simulations. The performance of the TRT, operating with two different gas mixtures (xenon-based and argon-based) and its dependence on the TRT occupancy is presented. Furthermore, these studies show that the tracking performance of the TRT is similar for the two gas mixtures and that a significant contribution to the particle momentum resolution is made by the TRT up to high particle densities.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Comparison between simulated and observed LHC beam backgrounds in the ATLAS experiment at E beam =4 TeV

Results of dedicated Monte Carlo simulations of beam-induced background (BIB) in the ATLAS experiment at the Large Hadron Collider (LHC) are presented and compared with data recorded in 2012. During normal physics operation this background arises mainly from scattering of the 4 TeV protons on residual gas in the beam pipe. Methods of reconstructing the BIB signals in the ATLAS detector, developed and implemented in the simulation chain based on the \textsc{Fluka} Monte Carlo simulation package, are described. The interaction rates are determined from the residual gas pressure distribution in the LHC ring in order to set an absolute scale on the predicted rates of BIB so that they can be compared quantitatively with data. Through these comparisons the origins of the BIB leading to different observables in the ATLAS detectors are analysed. The level of agreement between simulation results and BIB measurements by ATLAS in 2012 demonstrates that a good understanding of the origin of BIB has been reached.

47 OTHER INSTRUMENTATION↗
DOE OSTI2017

Mechanical Design Analysis of MQXFB, the 7.2-m-Long Low- $\beta$ Quadrupole for the High-Luminosity LHC Upgrade

As part of the High-Luminosity Large Hadron Collider (LHC) Project, a set of Nb 3 Sn quadrupoles are being developed, aiming to enhance the performance of the inner triplets. The new magnets, identified as MQXFA and MQXFB, will share the same cross section with two different lengths, 4.2 and 7.2 m, respectively. During the magnet development, three short models were tested, along with a number of mechanical models, demonstrating the capability of the magnet cross section to achieve the specified performances. The same performances are now required for the full-length magnets. To ensure this, the authors studied the impact of the magnet length on the capability of the structure to provide an adequate support to the coils. Finite element and simplified analytical models were used to evaluate the impact of the magnet length on the stresses in the magnet ends and coil elongation during powering. Lastly, the models were calibrated using the results from the short model tests, and used to provide an indication on the required prestress and its foreseen impact on the magnet performance.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗
DOE OSTI2018

Geometric Field Errors of Short Models for MQXF, the Nb3Sn Low-β Quadrupole for the High Luminosity LHC

© 2002-2011 IEEE. In the framework of the high-luminosity upgrade of the large hadron collider, the U.S. LARP collaboration and CERN are jointly developing a 150-mm aperture Nb3Sn quadrupole for the Large Hadron Collider (LHC) interaction regions. Due to the large beam size and orbit displacement in the final focusing triplet, MQXF has challenging targets for field quality at nominal operation conditions. Three short model magnets have been tested and around 30 coils have been built, allowing a first analysis of the reproducibility of the coil size and turns positioning. The impact of the coil shimming on field quality is evaluated, with special emphasis on the warm magnetic measurements and the correlation to field measurements at cold and nominal field. The variability of the field harmonics along the magnet axis is studied by means of a Monte-Carlo analysis and the effects of the corrective actions implemented to suppress the low-order unallowed multipoles are discussed.

Bermudez, Susana Izquierdo↗