[en] Results are reported on the measurement of the atmospheric neutrino-induced muon flux at a depth of 2 kilometers below the Earth's surface from 1229 days of operation of the Sudbury Neutrino Observatory (SNO). By measuring the flux of through-going muons as a function of zenith angle, the SNO experiment can distinguish between the oscillated and unoscillated portion of the neutrino flux. A total of 514 muonlike events are measured between -1≤cosθ_zenith≤0.4 in a total exposure of 2.30x10¹⁴ cm² s. The measured flux normalization is 1.22±0.09 times the Bartol three-dimensional flux prediction. This is the first measurement of the neutrino-induced flux where neutrino oscillations are minimized. The zenith distribution is consistent with previously measured atmospheric neutrino oscillation parameters. The cosmic ray muon flux at SNO with zenith angle cosθ_zenith>0.4 is measured to be (3.31±0.01(stat)±0.09(sys))x10^-10 μ/s/cm².

[en] Results are reported from a joint analysis of Phase I and Phase II data from the Sudbury Neutrino Observatory. The effective electron kinetic energy threshold used is T_eff=3.5 MeV, the lowest analysis threshold yet achieved with water Cherenkov detector data. In units of 10⁶ cm^-2 s^-1, the total flux of active-flavor neutrinos from ⁸B decay in the Sun measured using the neutral current (NC) reaction of neutrinos on deuterons, with no constraint on the ⁸B neutrino energy spectrum, is found to be Φ_NC=5.140_-0.158^+0.160(stat)_-0.117^+0.132(syst). These uncertainties are more than a factor of 2 smaller than previously published results. Also presented are the spectra of recoil electrons from the charged current reaction of neutrinos on deuterons and the elastic scattering of electrons. A fit to the Sudbury Neutrino Observatory data in which the free parameters directly describe the total ⁸B neutrino flux and the energy-dependent ν_e survival probability provides a measure of the total ⁸B neutrino flux Φ_⁸B=5.046_-0.152^+0.159(stat)_-0.123^+0.107(syst). Combining these new results with results of all other solar experiments and the KamLAND reactor experiment yields best-fit values of the mixing parameters of θ₁₂=34.06_-0.84^+1.16 degrees and Δm₂₁²=7.59_-0.21^+0.20x10^-5 eV². The global value of Φ_⁸B is extracted to a precision of _-2.95^+2.38%. In a three-flavor analysis the best fit value of sin²θ₁₃ is 2.00_-1.63^+2.09x10^-2. This implies an upper bound of sin²θ₁₃<0.057 (95% C.L.).

[en] The Di-pentagonal Array for Nuclear Timing Experiments (DANTE) is an array of ten BaF₂ detectors used in conjunction with the 8π gamma-ray spectrometer at the TRIUMF-ISAC radioactive-ion beam facility. DANTE is used to conduct direct lifetime measurements of nuclear excited states in the picosecond - nanosecond range. This, in turn, will aid in probing the collective structures of deformed nuclei. The capability of DANTE to measure nanosecond-scale lifetimes is demonstrated by using a ¹⁵²Eu source. The half-life of the I^π = 2₁⁺ state of ¹⁵²Sm is measured to be 1.426 ± 0.018 ns.

[en] A measurement of the ground state β-decay branching ratio of 62Ga has been made as part of a program of high-precision superallowed Fermi β decay studies at the ISAC radioactive beam facility. The experiment was conducted by detecting γ rays and β particles from the decay of 62Ga using the 8π γ-ray spectrometer and the SCEPTAR plastic scintillator array

[en] A high-precision branching ratio measurement for the superallowed β⁺ decay of ⁶²Ga was performed at the Isotope Separator and Accelerator (ISAC) radioactive ion beam facility. The 8π spectrometer, an array of 20 high-purity germanium detectors, was employed to detect the γ rays emitted following Gamow-Teller and nonanalog Fermi β⁺ decays of ⁶²Ga, and the SCEPTAR plastic scintillator array was used to detect the emitted β particles. Thirty γ rays were identified following ⁶²Ga decay, establishing the superallowed branching ratio to be 99.858(8)%. Combined with the world-average half-life and a recent high-precision Q-value measurement for ⁶²Ga, this branching ratio yields an ft value of 3074.3±1.1 s, making ⁶²Ga among the most precisely determined superallowed ft values. Comparison between the superallowed ft value determined in this work and the world-average corrected Ft value allows the large nuclear-structure-dependent correction for ⁶²Ga decay to be experimentally determined from the CVC hypothesis to better than 7% of its own value, the most precise experimental determination for any superallowed emitter. These results provide a benchmark for the refinement of the theoretical description of isospin-symmetry breaking in A≥62 superallowed decays

[en] The half-life of ³⁸K^m has been measured to be 924.46(14) ms, a result that is a factor of two more precise than any of the five previous measurements of this quantity. The previous results are not consistent with one another, but our result agrees well with the two most recent ones. The derived ft value for ³⁸K^m is now one of the three most precisely known superallowed ft values.

[en] The half-life of the superallowed β⁺ emitter ⁶²Ga has been measured at TRIUMF's Isotope Separator and Accelerator facility using a fast-tape-transport system and 4π continuous-flow gas proportional counter to detect the positrons from the decay of ⁶²Ga to the daughter ⁶²Zn. The result, T_1/2=116.100±0.025 ms, represents the most precise measurement to date (0.022%) for any superallowed β-decay half-life. When combined with six previous measurements of the ⁶²Ga half-life, a new world average of T_1/2=116.121±0.021 ms is obtained. This new half-life measurement results in a 20% improvement in the precision of the ⁶²Ga superallowed ft value while reducing its mean by 0.9σ to ft=3074.3(12) s. The impact of this half-life measurement on precision tests of the CVC hypothesis and isospin symmetry breaking corrections for A≥62 superallowed decays is discussed

[en] The branching ratio for the superallowed β⁺ decay of ³⁸K^m was measured at TRIUMF's ISAC radioactive ion beam facility. The M3 internal transition between the isomer and the ground state of ³⁸K^m was observed with a branching ratio of 330(43) ppm. A search for the nonanalogue β-decay branch to the first excited 0⁺ state in ³⁸Ar was also performed and yielded an upper limit of ≤12 ppm at 90% C.L. These measurements lead to a revised superallowed branching ratio for ³⁸K^m of 99.967(4)%, and increase the ³⁸K^m ft value by its entire quoted uncertainty to ft=3052.1(10) s. Implications for tests of the nuclear-structure dependent corrections in superallowed β decays and the extraction of the Cabibbo-Kobayashi-Maskawa matrix element V_ud are discussed

[en] The half-life of ¹⁸Ne has been determined by detecting 1042-keV γ rays in the daughter ¹⁸F following the superallowed-Fermi β⁺ decay of samples implanted at the center of the 8πγ-ray spectrometer, a spherical array of 20 HPGe detectors. Radioactive ¹⁸Ne beams were produced on-line, mass-separated, and ionized using an electron-cyclotron-resonance ionization source at the ISAC facility at TRIUMF in Vancouver, Canada. This is the first high-precision half-life measurement of a superallowed Fermi β decay to utilize both a large-scale HPGe spectrometer and the isotope separation on-line technique. The half-life of ¹⁸Ne, 1.6656 ± 0.0019 s, deduced following a 1.4σ correction for detector pulse pile-up, is four times more precise than the previous world average. As part of an investigation into potential systematic effects, the half-life of the heavier isotope ²³Ne was determined to be 37.11 ± 0.06 s, a factor of 2 improvement over the previous precision

[en] The Doppler-shift attenuation method was applied to measure the lifetime of the 4.03 MeV state in ¹⁹Ne. By utilizing a ³He-implanted Au foil as a target, the state was populated using the ²⁰Ne(³He, α)¹⁹Ne reaction in inverse kinematics at a ²⁰Ne beam energy of 34 MeV. De-excitation γ rays were detected in coincidence with α particles. At the 1σ level, the lifetime was determined to be 11_-3⁺⁴ fs and at the 95.45% confidence level the lifetime is 11_-7⁺⁸ fs