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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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We use positron annihilation spectroscopy to study positron kinetics in electrically-biased metal-oxide-silicon system and trapping at the SiO2/Si interface.
The radioisotope $^{125}\text{Xe}$ is a short-lived ($T_{1/2}\sim16.9 h$) activation product of the neutron calibrations performed in the LUX-ZEPLIN experiment. Subsequently, $^{125}$Xe decays primarily ($>99\%$) via electron capture, but positron emission has been confirmed by direct measurement to at least the 243 keV level of $^{125}\text{I}$. An additional decay to the 188keV level is expected from triple-coincident measurements of the annihilation and relaxation $γ$ rays, but has not been directly confirmed. By utilizing multiple-scatter event analysis and the pre-activation data to constrain backgrounds, this work reports positron emission with a statistical significance of 5.5$σ$. This corresponds to a total branching ratio of $0.29\pm0.08_{\text{stat.}}\pm0.04_{\text{sys.}}$%, and is the first constraint to the individual branching levels of $^{125}\text{I}$.
Positron annihilation in condensed gases - helium, hydrogen, nitrogen, & oxygen
Positron scintillation camera for detecting real and simulated brain tumors
Positron-electron ratio of precipitating electrons
Positron-electron ratio in primary cosmic radiation measured as function of energy - cosmic ray origin
Free-positron annihilation mean life in diatomic and rare gases as a function of first electron ionization potential and outermost electron density
Tables of energy losses and ranges of electrons and positrons
Positron s-wave elastic scattering by atomic hydrogen below inelastic threshold analyzed, using Dalgarno-Lynn second order adiabatic potential
Minimum principle for single channel scattering applied to S-wave elastic-scattering phase shift of positrons by atomic hydrogen
Ratio of electron to positrons in primary cosmic radiation investigated by balloon-borne instrument over Ft. Churchill
Theory of low energy positron helium scattering below positronium threshold - adiabatic method applied
Balloon flight data on cosmic ray electron- positron ratio from 100 MeV to 3 BeV
Positron scattering by atomic hydrogen for various incident energies
Intensity and spectra of cosmic ray electrons and positrons in determining mean confinement time, density and solar modulation
Modified adiabatic scattering function applied to positron annihilation in helium
Modified adiabatic scattering function applied to positron annihilation in helium
Resonances in proton hydrogen and positron hydrogen scattering predicted at energies just below excitation thresholds