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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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At least 487 records · Page 27
All sourcesNASA NTRSDOE OSTI
NASA NTRS1985

Dependence of the average spatial and energy characteristics of the hadron-lepton cascade on the strong interaction parameters at superhigh energies

A method for calculating the average spatial and energy characteristics of hadron-lepton cascades in the atmosphere is described. The results of calculations for various strong interaction models of primary protons and nuclei are presented. The sensitivity of the experimentally observed extensive air showers (EAS) characteristics to variations of the elementary act parameters is analyzed.

Boyadjian, N. G.↗
NASA NTRS1985

Hadronic components of EAS by rigorous saddle point method in the energy range between 10(5) and 10(8) GeV

The study of hadronic components in the high energy range between 10 to the 5 and 10 to the 8 Gev exhibits by far the strongest mass sensitivity since the primary energy spectrum as discussed by Linsley and measured by many air shower experimental groups indicates a change of slope from -1.7 to 2.0 in this energy range. This change of slope may be due to several reasons such as a genuine spectral feature of astrophysical origin, a confinement effect of galactic component or a rather rapid change of mass, a problem which we have attempted to study here in detail.

Sinha, M.↗
NASA NTRS1984

Phenomenology of soft hadron interactions and the relevant EAS data

The interpretation of the experimental data in superhigh energy cosmic rays requires the calculations using various models of elementary hadron interaction. One should prefer the models justified by accelerator data and giving definite predictions for superhigh energies. The model of quark-gluon pomeron strings (the QGPS models) satisfies this requirement.

Kalmykov, N. N.↗
NASA NTRS1985

Energetic delayed hadrons in large air showers observed at 5200m above sea level

Energetic delayed hadrons in air showers with electron sizes in the range 10 to the 6th power to 10 to the 9th power were studied by observing the delayed bursts produced in the shield of nine square meter scintillation detectors in the Chacaltaya air-shower array. The frequency of such delayed burst is presented as a function of electron size, core distance and sec theta.

Kaneko, T.↗
NASA NTRS1987

The quark-hadron phase transition and primordial nucleosynthesis

After presenting the current view of the processes taking place during the cosmological transition from 'quark soup' to normal hadron matter, attention is given to what happens to cosmological nucleosynthesis in the presence of small-scale baryon inhomogeneities. The QCD phase transition is among the plausible sources of this inhomogeneity. It is concluded that the formation of primordial 'quark nuggets' and other cold exotica requires very low entropy regions at the outset, and that even the more modest nonlinearities perturbing nucleosynthesis probably require some ingredient in addition to a quiescent, mildly supercooled transition.

Hogan, Craig J.↗
NASA NTRS1989

Neutron stars: A cosmic hadron physics laboratory

A progress report is given on neutron stars as a cosmic hadron physics laboratory. Particular attention is paid to the crustal neutron superfluid, and to the information concerning its properties which may be deduced from observations of pulsar glitches and postglitch behavior. Current observational evidence concerning the softness or stiffness of the high density neutron matter equation of state is reviewed briefly, and the (revolutionary) implications of a confirmation of the existence of a 0.5 ms pulsar at the core of (Supernova) SN1987A are discussed.

Pines, David↗
NASA NTRS1989

Big Bang nucleosynthesis and the Quark-Hadron transition

An examination and brief review is made of the effects of quark-hadron transistion induced fluctuations on Big Bang nucleosynthesis. It is shown that cosmologically critical densities in baryons are difficult to reconcile with observation, but the traditional baryon density constraints from homogeneous calculations might be loosened by as much as 50 percent, to 0.3 of critical density, and the limit on the number of neutrino flavors remains about N(sub nu) is less than or approximately 4. To achieve baryon densities of greater than or approximately 0.3 of critical density would require initial density contrasts R is much greater the 10(exp 3), whereas the simplest models for the transition seem to restrict R to less than of approximately 10(exp 2).

Kurki-Suonio, Hannu↗
NASA NTRS1990

Big bang nucleosynthesis and the quark-hadron transition

An examination and brief review is made of the effects of quark-hadron transition induced fluctuations on Big Bang nucleosynthesis. It is shown that cosmologically critical densities in baryons are difficult to reconcile with observation, but the traditional baryon density constraints from homogeneous calculations might be loosened by as much as 50 percent, to 0.3 of critical density, and the limit on the number of neutrino flavors remains about N(sub nu) is less than or approximately 4. To achieve baryon densities of greater than or approximately 0.3 of critical density would require initial density contrasts R is much greater the 10(exp e), whereas the simplest models for the transition seem to restrict R to less than of approximately 10(exp 2).

Kurki-Suonio, Hannu↗
NASA NTRS1989

Neutron stars - A cosmic hadron physics laboratory

A progress report is given on neutron stars as a cosmic hadron physics laboratory. Particular attention is paid to the crustal neutron superfluid, and to the information concerning its properties which may be deduced from observations of pulsar glitches and postglitch behavior. Current observational evidence concerning the softness or stiffness of the high density neutron matter equation of state is reviewed briefly, and the (revolutionary) implications of a confirmation of the existence of a 0.5 ms pulsar at the core of (Supernova) SN1987A are discussed.

Pines, David↗
NASA NTRS1991

Red-giant evolution, metallicity, and new bounds on hadronic axions

Stellar cooling by nuclear axion emission is explored, identifying those special isotopes that dominate this process for temperatures from 10 to the 7th to 10 to the 9th K. It is argued that such nuclear energy-loss mechanisms are distinctive because the effects track metallicity. Three observables associated with evolution of stars along the red-giant and horizontal branches are shown to impose new and restrictive constraints on axions in the hadronic window.

Haxton, W. C.↗
NASA NTRS1995

Relativistic hadrons and the origin of relativistic outflows in active galactic nuclei

We examine the hydrodynamic origin of relativistic outflows in active galactic nuclei (AGN). Specifically, we propose that the presence of a population of relativistic hadrons in the AGN 'central engine' and the associated neutron production suffices to produce outflows which under rather general conditions could be relativistic. The main such condition is that the size of the neutron production region be larger than the neutron flight path tau(sub n) approximately 3 x 10(exp 13) cm. This condition guarantees that the mean energy per particle in the proton fluid, resulting from the decay of the neutrons outside their production region, be greater than the proton rest mass. The expansion of this fluid can then lead naturally to a relativistic outflow by conversion of its internal energy to directed motion. We follow the development of such flows by solving the mass, energy as well as the kinetic equation for the proton gas in steady state, taking into account the source terms due to compute accurately the adiabatic index of the expanding gas, and in conjunction with Bernoulli's equation the detailed evolution of the bulk Lorentz factor. We further examine the role of large-scale magnetic fields in confining these outflows to produce the jets observed at larger scales.

Contopoulos, John↗
DOE OSTI2020

The United States at the Large Hadron Collider

Why the Large Hadron Collider at CERN? The LHC, located near Geneva, Switzerland, is the world’s most powerful particle collider. It accelerates and smashes atomic nuclei together, recreating the energetic conditions that existed after the Big Bang and generating new particles. Huge detectors record the collisions, and scientists study the products.

43 PARTICLE ACCELERATORS↗
DOE OSTI2020

Damping rate limitations for transverse dampers in large hadron colliders

The paper focuses on two issues important for design and operation of bunch-by-bunch transverse damper in a very large hadron collider, where fast damping is required to suppress beam instabilities and noise induced emittance growth. The first issue is associated with kick variation along a bunch which affects the damping of head-tail modes. The second issue is associated with affect of damper noise on the instability threshold.

43 PARTICLE ACCELERATORS↗
DOE OSTI2021

Review of opportunities for new long-lived particle triggers in Run 3 of the Large Hadron Collider

Long-lived particles (LLPs) are highly motivated signals of physics Beyond the Standard Model (BSM) with great discovery potential and unique experimental challenges. The LLP search programme made great advances during Run 2 of the Large Hadron Collider (LHC), but many important regions of signal space remain unexplored. Dedicated triggers are crucial to improve the potential of LLP searches, and their development and expansion is necessary for the full exploitation of the new data. The public discussion of triggers has therefore been a relevant theme in the recent LLP literature, in the meetings of the LLP@LHC Community workshop and in the respective experiments. This paper documents the ideas collected during talks and discussions at these Workshops, benefiting as well from the ideas under development by the trigger community within the experimental collaborations. We summarise the theoretical motivations of various LLP scenarios leading to highly elusive signals, reviewing concrete ideas for triggers that could greatly extend the reach of the LHC experiments. We thus expect this document to encourage further thinking for both the phenomenological and experimental communities, as a stepping stone to further develop the LLP@LHC physics programme.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

A general-mass scheme for prompt charm production at hadron colliders

In these proceedings, we apply the recently developed S-ACOT-MPS factorization scheme at the next-to-leading order to prompt charm production at hadron colliders. It provides a good agreement with experimental data on charm meson production measured by LHCb at 7 and 13 TeV. The low-$p_T$ data are on the margins of the theoretical error bands, emphasizing the importance of including contributions beyond the next-to-leading order.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2021

Autoencoders on FPGAs for real-time, unsupervised new physics detection at 40 MHz at the Large Hadron Collider

In this paper, we show how to adapt and deploy anomaly detection algorithms based on deep autoencoders, for the unsupervised detection of new physics signatures in the extremely challenging environment of a real-time event selection system at the Large Hadron Collider (LHC). We demonstrate that new physics signatures can be enhanced by three orders of magnitude, while staying within the strict latency and resource constraints of a typical LHC event filtering system. This would allow for collecting datasets potentially enriched with high-purity contributions from new physics processes. Through per-layer, highly parallel implementations of network layers, support for autoencoder-specific losses on FPGAs and latent space based inference, we demonstrate that anomaly detection can be performed in as little as $80\,$ns using less than 3% of the logic resources in the Xilinx Virtex VU9P FPGA. Opening the way to real-life applications of this idea during the next data-taking campaign of the LHC.

46 INSTRUMENTATION RELATED TO NUCLEAR SCIENCE AND ↗
DOE OSTI2021

Hadronic vacuum polarization of the muon on 2+1+1-flavor HISQ ensembles: an update

We give an update on the status of the Fermilab Lattice-HPQCD-MILC calculation of the contribution to the muon's anomolous magnetic moment from the light-quark, connected hadronic vacuum polarization. We present preliminary, blinded results in the intermediate window for this contribution, $a_{\mu, \textrm{W}}^{ll}$. The calculation is performed on $N_f =2+1+1$ highly-improved staggered quark (HISQ) ensembles from the MILC collaboration with physical pion mass at four lattice spacings between 0.15 fm and 0.06 fm. We also present preliminary results for a study of the two-pion contributions to the vector-current correlation function performed on the 0.15 fm ensemble where we see a factor of four improvement over traditional noise reduction techniques.

Lahert, Shaun↗