0000000000403046
AUTHOR
M. M. Fowler
Radiative lifetimes of Am I atomic levels.
The lifetimes of several atomic levels of Am I that are connected by electric dipole transitions to the ground state have been measured. The Am atoms were excited by light pulses from a cw single-mode dye laser with the aid of an optoacoustic modulator. The decay curve of the delayed emitted photons was measured by counting single photons in the beam-off periods. The lifetimes of 14 levels in the wavelength region between 6405 and 4265 A were measured using Am-metal vapor. The metallic Am was obtained by reducing AmO/sub 2/ with La at 1500 /sup 0/C in a high-vacuum system and collecting Am on a catcher foil. The Am vapor was then produced by controlled reevaporation from the foil at a tempe…
Direct evidence for neutrino flavor transformation from neutral-current interactions in the Sudbury Neutrino Observatory
Observations of neutral current neutrino interactions on deuterium in the Sudbury Neutrino Observatory are reported. Using the neutral current, elastic scattering, and charged current reactions and assuming the standard 8B shape, the electron-neutrino component of the 8B solar flux is 1.76 +/-0.05(stat.)+/-0.09(syst.) x10^6/(cm^2 s), for a kinetic energy threshold of 5 MeV. The non-electron neutrino component is 3.41+/-0.45(stat.)+0.48,-0.45(syst.) x10^6/(cm^2 s), 5.3 standard deviations greater than zero, providing strong evidence for solar electron neutrino flavor transformation. The total flux measured with the NC reaction is 5.09 +0.44,-0.43(stat.)+0.46,-0.43(syst.)x10^6/(cm^2 s), consi…
Measurement of day and night neutrino energy spectra at SNO and constraints on neutrino mixing parameters
The Sudbury Neutrino Observatory (SNO) has measured day and night solar neutrino energy spectra and rates. For charged current events, assuming an undistorted $^8$B spectrum, the night minus day rate is $14.0% \pm 6.3% ^{+1.5}_{-1.4}%$ of the average rate. If the total flux of active neutrinos is additionally constrained to have no asymmetry, the $\nu_e$ asymmetry is found to be $7.0% \pm 4.9% ^{+1.3}_{-1.2}%$. A global solar neutrino analysis in terms of matter-enhanced oscillations of two active flavors strongly favors the Large Mixing Angle (LMA) solution.
Attempts to Produce Superheavy Elements by Fusion ofCa48withCm248in the Bombarding Energy Range of 4.5-5.2 MeV/u
A search for superheavy elements was made in bombardments of $^{248}\mathrm{Cm}$ with $^{48}\mathrm{Ca}$ ions performed at projectile energies close to the interaction barrier in order to keep the excitation energy of the compound nucleus $Z=116$, $A=296$ as low as possible. No evidence for superheavy nuclei was obtained in a half-life region from 1 \ensuremath{\mu}s to 10 yr with a production cross section greater than ${10}^{\ensuremath{-}34}$ to ${10}^{\ensuremath{-}35}$ ${\mathrm{cm}}^{2}$.