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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 1,729 records · Page 96
All sourcesNASA NTRSDOE OSTI
DOE OSTI2018

Hadronic Decays of the D s Meson

The $D^+ _s$ (formerly F + ) is the lowest-lying pseudoscalar meson containing charm and anti-strange quarks. Evidence for this state was first reported in 1977, although more recent observations disagree with some of the early results. Since 1983 the weakly decaying $D^+ _s$ has been observed in many experiments.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2018

Computing the Properties of Hadrons, Nuclei, and Nuclear Matter from Quantum Chromodynamics, UNC-CH Final Report.

This is the final technical report for the UNC-CH component of a SciDAC3 project. This project served to coordinate the software development effort which the nuclear physics lattice QCD community is developing to ensure that lattice calculations can make optimal use of forthcoming leadership-class and dedicated hardware, including those of the national laboratories, and prepares for the exploitation of future computational resources in the exascale era. The project developed and optimized simulation software for lattice QCD calculations on leadership class computers and on GPUaccelerated heterogeneous architectures. The participating team at multiple instritutions improved and extended software libraries (Chroma, CPS, MILC, QLUA, QPhiX, QDP++, QDP-jit) by providing interfaces for heterogeneous computing environments and through the optimization of gauge field evolution algorithms and sparse matrix inverters. The former includes the development of new multi-time scale integrators and the latter focused on the development of new multi-grid and domain decomposition inverters for several QCD fermion discretization schemes. The sub-project at the University of North Carolina worked towards the development a domain specific language for lattice QCD computations with the express purpose of generating code with uncompromised performance.

97 MATHEMATICS AND COMPUTING↗
DOE OSTI2019

Hadronic parity violation in few-nucleon systems

The research performed under this award contributed to progress made in recent years in understanding the interplay of two fundamental forces, the strong and weak interactions, in nuclei. This information is valuable in achieving one of the main goals of nuclear physics - the understanding of how properties of nuclei can be linked to the underlying Standard Model. In particular, this project focused on the nonconservation of parity, which provides a unique signature of the highly suppressed weak interactions in the nuclear environment, as well as other symmetries. One major achievement of this project was the establishment of a hierarchy of the various parity-violating interactions, based on an approximation scheme that has proved highly successful in other nuclear physics applications. These results have significant implications for the analysis and interpretation of a number of experiments already performed, including at US National Laboratories, as well as for the planning of future experiments. The same methods were then also extended to the breaking of time reversal invariance. In addition, the project provided important input into a feasibility study of a possible future parity nonconservation experiment using polarized photon beams. Finally, this project addressed how to properly describe the possible violation of Lorentz invariance in terms of experimentally accessible particles and how they relate to the underlying theoretical framework in terms of Standard Model degrees of freedom.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2020

Updating Hadron Production Models to Better Predict Neutrino Flux for DUNE

The Deep Underground Neutrino Experiment (DUNE) is an ongoing project at Fermilab with international collaboration and over 190 institutions involved. DUNE has three primary science goals, one of which is searching for the origin of the imbalance of matter and antimatter in the universe. Accomplishing this goal will require the study of neutrinos and the phenomenon of neutrino oscillation.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Investigations of Baryon Spectroscopy via Electromagnetic and Hadronic Scattering (Final Report, May 1, 2019 to August 15, 2021)

The principal goal of this project is the experimental and phenomenological study of baryon spectroscopy. The P.I.’s group currently consists of himself and one student, Mr. Haoran Sun. Haoran’s project involves a new coupled-channel partial-wave analysis of all available world data for the reactions $K^0_Lp → K^0_Sp, K^+p → K^+p, K^+n → K^0p, K^0p → K^+n$, and $K^+n → K^+n$. The analysis of Mr. Sun is related to a conditionally approved proposal to develop a secondary $K^0_L$ beamline in Hall D at JLab, to be used with the GlueX setup. Mr. Sun’s analysis will establish some of the software codes necessary to analyze some of the data that could be measured at this facility. More importantly, the analysis will provide new experimental constraints on important background $\textit{KN}$ reactions, which are needed in order to help understand data that involve formation of Λ$^{\ast}$ and Σ$^{\ast}$ resonances.

72 PHYSICS OF ELEMENTARY PARTICLES AND FIELDS↗
DOE OSTI2023

Development of High Performance Medium Velocity Superconducting Elliptical Cavities for Hadron Linacs

There is a solid scientific need for continuous wave (CW) proton or heavy ion linear accelerators (linacs) in the energy range up to about 1 GeV per nucleon (GeV/u). Only superconducting (SC) cavities can provide cost-efficient acceleration in CW mode. While low velocity, bc < 0.5 (b is the relative velocity of a charged particle and c is the speed of light), and high velocity, bc > 0.9, SC accelerating structures are established, there is a need in high-performance medium velocity SC accelerating structures. Currently, no superconducting (SC) CW proton or ion accelerators operate in the medium velocity range. We have developed a robust technology for producing high-performance medium-velocity elliptical cavities operating in the frequency range between 600 and 700 MHz. The project was performed in collaboration with Fermi and Argonne National Laboratories. The 5-cell, βopt = 0.65, 644 MHz elliptical cavities built at MSU have been used for this research. An advanced surface treatment method based on nitrogen doping to achieve a high-quality factor and a high accelerating gradient has been demonstrated. The surface treatment has been performed at ANL, and nitrogen doping at FNAL. A stable resonance control with the slow and fast tuner system has also been verified. FNAL developed a dedicated resonance control system for the stable operation of the combined tuner.

43 PARTICLE ACCELERATORS↗