RESUMO
The absolute scale of the neutrino mass plays a critical role in physics at every scale, from the subatomic to the cosmological. Measurements of the tritium end-point spectrum have provided the most precise direct limit on the neutrino mass scale. In this Letter, we present advances by Project 8 to the cyclotron radiation emission spectroscopy (CRES) technique culminating in the first frequency-based neutrino mass limit. With only a cm^{3}-scale physical detection volume, a limit of m_{ß}<155 eV/c^{2} (152 eV/c^{2}) is extracted from the background-free measurement of the continuous tritium beta spectrum in a Bayesian (frequentist) analysis. Using ^{83m}Kr calibration data, a resolution of 1.66±0.19 eV (FWHM) is measured, the detector response model is validated, and the efficiency is characterized over the multi-keV tritium analysis window. These measurements establish the potential of CRES for a high-sensitivity next-generation direct neutrino mass experiment featuring low background and high resolution.
Assuntos
Fator VII/análise , Fator VII/genética , Polimorfismo de Nucleotídeo Único/fisiologia , Regiões Promotoras Genéticas/genética , Idoso , Dietoterapia , Ácidos Graxos Ômega-3/administração & dosagem , Ácidos Graxos Ômega-3/farmacologia , Frequência do Gene , Genótipo , Haplótipos , Humanos , MasculinoRESUMO
OBJECTIVE: The use of camp stoves in an enclosed or poorly ventilated space is clearly not recommended due to the risk of carbon monoxide (CO) poisoning. Instances may arise, however, when use for a limited time is necessary. We sought to find differences in CO levels between various fuels used to power a commercially available camp stove. METHODS: A comparison was made between unleaded gasoline, kerosene, and white gas (Coleman fuel). The stove, fuels, and CO detector were all purchased from local retailers. A 0.4-m3 space was constructed with a cardboard box. Three trials were performed using each fuel in which water was heated over the stove for 5 minutes. Measurement of the CO level within the box was taken every 30 seconds. RESULTS: Kerosene created CO levels of 714 (SD = 113.5) parts per million (ppm) at 2 1/2 minutes but was out of the measurable range of >999 ppm within 4 minutes on each of its trials. White gas burned the cleanest, with an average of 212 ppm (SD = 27.8) at 2 1/2 minutes and 348 ppm (SD = 76.0) at 5 minutes. Unleaded gasoline created 305 ppm (SD = 27.1) at 2 1/2 minutes and 464 ppm (SD = 31.6) at 5 minutes. CONCLUSION: All of the fuels created a high level of CO in a short period of time. White gas burned the cleanest and would be preferred to unleaded gasoline or kerosene in the event that the unvented use of a camp stove was necessary.