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Results for “WEAK INTERACTIONS”

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 19 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2017

Light weakly interacting massive particles

Light WIMPs are dark matter particle candidates with weak scale interaction with the known particles, and mass in the GeV to 10's of GeV range. Hints of light WIMPs have appeared in several dark matter searches in the last decade. The unprecedented possible coincidence into tantalizingly close regions of mass and cross section of four separate direct detection experimental hints and a potential indirect detection signal in gamma rays from the galactic center, aroused considerable interest in our field. Even if these hints did not so far result in a discovery, they have had a significant impact in our field. Herein we discuss the evidence for and against light WIMPs as dark matter candidates and discuss future relevant experiments and observations

79 ASTRONOMY AND ASTROPHYSICS↗
DOE OSTI2016

New Results from the Search for Low-Mass Weakly Interacting Massive Particles with the CDMS low ionization Threshold Experiment

The CDMS low ionization threshold experiment (CDMSlite) uses cryogenic germanium detectors operated at a relatively high bias voltage to amplify the phonon signal in the search for weakly interacting massive particles (WIMPs). Results are presented from the second CDMSlite run with an exposure of 70 kg day, which reached an energy threshold for electron recoils as low as 56 eV. A fiducialization cut reduces backgrounds below those previously reported by CDMSlite.

New Results, Low-Mass, Mazzive Particles, CDMS Low↗
NASA NTRS1989

Cosmology and the weak interaction

The weak interaction plays a critical role in modern Big Bang cosmology. Two of its most publicized comological connections are emphasized: big bang nucleosynthesis and dark matter. The first of these is connected to the cosmological prediction of neutrine flavors, N(sub nu) is approximately 3 which in now being confirmed. The second is interrelated to the whole problem of galacty and structure formation in the universe. The role of the weak interaction both for dark matter candidates and for the problem of generating seeds to form structure is demonstrated.

Schramm, David N.↗
DOE OSTI2015

Weak interactions between water and clathrate-forming gases at low pressures

Using scanning probe microscopy and temperature programed desorption we examined the interaction between water and two common clathrate-forming gases, methane and isobutane, at low temperature and low pressure. Water co-deposited with up to 10-1 mbar methane or 10-5 mbar isobutane at 140 K onto a Pt(111) substrate yielded pure crystalline ice, i.e., the exposure to up to ~107 gas molecules for each deposited water molecule did not have any detectable effect on the growing films. Exposing metastable, less than 2 molecular layers thick, water films to 10-5 mbar methane does not alter their morphology, suggesting that the presence of the Pt(111) surface is not a strong driver for hydrate formation. This weak water-gas interaction at low pressures is supported by our thermal desorption measurements from amorphous solid water and crystalline ice where 1 ML of methane desorbs near ~43 K and isobutane desorbs near ~100 K. Similar desorption temperatures were observed for desorption from amorphous solid water.

Clathrates↗
DOE OSTI2019

Spin-energy correlation in degenerate weakly interacting Fermi gases

Weakly interacting Fermi gases exhibit rich collective dynamics in spin-dependent potentials, arising from correlations between spin degrees of freedom and conserved single-atom energies, offering broad prospects for simulating many-body quantum systems by engineering energy-space “lattices,” with controlled energy landscapes and site-to-site interactions. Using quantum-degenerate clouds of 6 Li, confined in a spin-dependent harmonic potential, we measure complex, time-dependent spin-density profiles, varying on length scales much smaller than the cloud size. We demonstrate that a one-dimensional mean-field model, without additional simplifying approximations, quantitatively predicts the observed fine structure. We calculate the magnetic fields where the scattering lengths vanish for three different hyperfine state mixtures to provide constraints on the collisional (Feshbach) resonance parameters.

74 ATOMIC AND MOLECULAR PHYSICS↗
NASA NTRS1976

Weak interactions and Eotvos experiments

A current-current model for weak interactions is used to show that the weak-interaction contribution to the ground-state energies of typical nuclei is about one part in 100 million of their rest masses. By comparing this contribution with the results of recent versions of the Eotvos experiments, it is concluded that weak-interaction energies obey the principle of equivalence to better than one part in 100, thus refuting claims that those experiments did not test weak-interaction effects.

Haugan, M. P.↗
DOE OSTI2021

The TAMUTRAP facility: A Penning trap facility at Texas A&M University for weak interaction studies

The Texas A&M University Penning Trap (TAMUTRAP) facility aims to test the standard model of the electroweak interaction by measuring the β-ν correlation parameter, a βν , for β-delayed proton emitters in the atomic mass range 20 < A < 40. Precision measurements of this correlation parameter and, inextricably, the Fierz interference parameter, are a sensitive probe of physics beyond the standard model. Here, using off-line ion sources, the TAMUTRAP facility has been commissioned by demonstrating the ability to manipulate the trapped-ion motions as well as to perform precision mass measurements. Our novel cylindrical Penning trap – the world's largest – differs from typical designs in two key aspects: the electrode structure has an 180-mm inner diameter and an overall length of 334.89 mm leading to a uniquely small length/radius ratio l/r = 3.72; and we do not use the long end cap approximation, instead our short endcap electrodes are closed and capable of being placed at an arbitrary potential. This geometry is optimized for observing β-delayed proton decays, but is also well suited for other in-trap and post-trap precision decay experiments. In addition to presenting an overview of the TAMUTRAP facility, we demonstrate that our unique Penning trap is able to measure masses with a precision similar to typical trap designs.

47 OTHER INSTRUMENTATION↗
NASA NTRS1981

Development of a direct experimental test for any violation of the equivalence principle by the weak interaction

Violation of the equivalence principle by the weak interaction is tested. Any variation of the weak interaction coupling constant with gravitational potential, i.e., a spatial variation of the fundamental constants is investigated. The level of sensitivity required for such a measurement is estimated on the basis of the size of a change in the gravitational potential which is accessible. The alpha particle spectrum is analyzed, and the counting rate was improved by a factor of approximately 100.

Parker, P. D. M.↗
DOE OSTI2017

Measurement-induced deterministic and probabilistic entanglement with strong and weak interactions

A scheme is proposed to transform spatial coherence of a single particle into entanglement. Two quantum systems can be entangled by having them interact in parallel with an ancillary particle in a Mach–Zehnder interferometer, then making a suitable post-selection of the particle followed by a conditional feedforward on one of the systems to be entangled. For a strong interaction between each system and the ancilla, the process works deterministically. For a weaker interaction only the probability of success is reduced, but the output continues to be a maximally entangled state. It is demonstrated that the process is optimal when the two interactions are symmetric, systems with continuous variables are considered, and the effects of the environment are taken into account. - Highlights: • Presents a scheme for deterministic entanglement based on feedforward, if a strong interaction is available. • Presents a scheme for probabilistic entanglement, if only a weak interaction is available. • Specifies the importance of an equal interaction strength in both arms. • Includes the effects of the environment and of the internal degrees of freedom of the ancilla.

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
DOE OSTI2015

Weak-interaction processes in core-collapse supernovae

Weak interaction processes play an important role for the dynamics of a core-collapse supernova. Due to progress of nuclear modeling and constrained by data it has been possible to improve the rates of these processes for supernova conditions decisively. This manuscript describes the recent advances and the current status in deriving electron capture rates on nuclei and of inelastic neutrino-nucleus scattering for applications in supernova simulations and briefly discusses their impact on such studies.

73 NUCLEAR PHYSICS AND RADIATION PHYSICS↗
DOE OSTI2014

Review Article: The weak interactive characteristic of resonance cells and broadband effect of metamaterials

Metamaterials are artificial media designed to control electromagnetic wave propagation. Due to resonance, most present-day metamaterials inevitably suffer from narrow bandwidth, extremely limiting their practical applications. On the basis of tailored properties, a metamaterial within which each distinct unit cell resonates at its inherent frequency and has almost no coupling effect with the other ones, termed as weak interaction system, can be formulated. The total response of a weak interaction system can be treated as an overlap of the single resonance spectrum of each type of different unit cells. This intriguing feature therefore makes it possible to accomplish multiband or broadband metamaterials in a simple way. By introducing defects into metamaterials to form a weak interaction system, multiband and broadband electromagnetic metamaterials have first been experimentally demonstrated by our group. The similar concept can also be readily extended to acoustic and seismic metamaterials.

36 MATERIALS SCIENCE↗
DOE OSTI2021

The repulsive Casimir-type forces in binary mixture of weakly interacting Bose–Einstein condensates gases

Highlights: • The equations of the state of a binary mixture weakly interacting Bose gases are established based on the Lagrangian of the system. • The formulae of the Casimir-type energy and the resulting Casimir-type force are produced from the quantum part of the grand canonical energy. • The results for the Casimir-type effect in the one-field case can be re-obtained by using the results of the two-field case. Within the framework of the quantum field theory (QFT) in the one-loop approximation, we investigate the Casimir-type effect in a mixture of two-component weakly interacting Bose-Einstein condensates (BECs) gases confined between two parallel plates at zero temperature. The Casimir-type forces in the miscible state of BECs for different boundary conditions (BCs) are discovered and compared to each other. The repulsive nature of the Casimir-type force in BECs is defined for the first time. Our calculations are finished in both grand canonical ensemble (GCE) and canonical ensemble (CE).

71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSIC↗
NASA NTRS1978

An experiment to verify that the weak interactions satisfy the strong equivalence principle

The construction of a clock based on the beta decay process is proposed to test for any violations by the weak interaction of the strong equivalence principle bu determining whether the weak interaction coupling constant beta is spatially constant or whether it is a function of gravitational potential (U). The clock can be constructed by simply counting the beta disintegrations of some suitable source. The total number of counts are to be taken a measure of elapsed time. The accuracy of the clock is limited by the statistical fluctuations in the number of counts, N, which is equal to the square root of N. Increasing N gives a corresponding increase in accuracy. A source based on the electron capture process can be used so as to avoid low energy electron discrimination problems. Solid state and gaseous detectors are being considered. While the accuracy of this type of beta decay clock is much less than clocks based on the electromagnetic interaction, there is a corresponding lack of knowledge of the behavior of beta as a function of gravitational potential. No predictions from nonmetric theories as to variations in beta are available as yet, but they may occur at the U/sg C level.

Eby, P. B.↗