Fast neutron activation of ubiquitous materials.

Nuclear explosions expose ubiquitous materials to large numbers of neutrons, producing a variety of radioactive isotopes. To simulate such phenomena from both fission and thermonuclear explosions, we irradiated 29 different targets with approximately 3 and 14 MeV neutrons and measured the beta-delayed gamma rays using germanium detectors. For each neutron energy, the expected radioisotopes, half-lives, and gamma ray energies were deduced. From measurements of the ratios of activities of the radionuclides produced by neutron irradiations, we were able to identify several materials that are particularly sensitive to the neutron energy spectra.

Limb length discrepancy and gait parameters of amateur football players in Lagos State, Nigeria.

Background: Football is a widely played sport globally. Limb length discrepancies have been found to be common among football players and these may lead to abnormal gait. Objectives: The purpose of this study was to determine the relationship between limb length discrepancy (LLD) and gait parameters of amateur football players in Lagos State, Nigeria. Methods: Eighty-nine amateur football players participated in the cross-sectional study. They were recruited from different stadia in Lagos State. Limb length and gait parameters were measured using tape and footprint measurements. Results: The prevalence of real limb length discrepancy among the participants was 75% (n = 67). The results of this study showed that the right leg was the shorter leg in 60% (n = 53) of the participants. There was no significant correlation between gait parameters and limb length measurement. Conclusion: Although limb length discrepancy is common among amateur football players in Lagos State, the relationship between limb length and gait parameters is weak.

Low-Energy Physics Reach of Xenon Detectors for Nuclear-Recoil-Based Dark Matter and Neutrino Experiments.

Dual-phase xenon detectors lead the search for keV-scale nuclear recoil signals expected from the scattering of weakly interacting massive particle (WIMP) dark matter, and can potentially be used to study the coherent nuclear scattering of MeV-scale neutrinos. New capabilities of such experiments can be enabled by extending their nuclear recoil searches down to the lowest measurable energy. The response of the liquid xenon target medium to nuclear recoils, however, is not well characterized below a few keV, leading to large uncertainties in projected sensitivities. In this work, we report a new measurement of ionization signals from nuclear recoils in liquid xenon down to the lowest energy reported to date. At 0.3 keV, we find that the average recoil produces approximately one ionization electron; this is the first measurement of nuclear recoil signals at the single-ionization-electron level, approaching the physical limit of liquid xenon ionization detectors. We discuss the implications of these measurements on the physics reach of xenon detectors for nuclear-recoil-based WIMP dark matter searches and the detection of coherent elastic neutrino-nucleus scattering.