Search

This Letter reports results from the NEMO-3 experiment based on an exposure of 1275 days with 661g of 130Te in the form of enriched and natural tellurium foils. With this data set the double beta decay rate of 130Te is found to be non-zero with a significance of 7.7 standard deviations and the half-life is measured to be T1/2 = (7.0 +/- 0.9(stat) +/- 1.1(syst)) x 10^{20} yr. This represents the most precise measurement of this half-life yet published and the first real-time observation of this decay.

We report results from the NEMO-3 experiment based on an exposure of 1275 days with 661 g of (130)Te in the form of enriched and natural tellurium foils. The ββ decay rate of (130)Te is found to be greater than zero with a significance of 7.7 standard deviations and the half-life is measured to be T(½)(2ν) = [7.0 ± 0.9(stat) ± 1.1(syst)] × 10(20) yr. This represents the most precise measurement of this half-life yet published and the first real-time observation of this decay.

No evidence for the neutrinoless double-\ensuremath{\beta} decay of $^{100}\mathrm{Mo}$ has been found in a search using a segmented Si(Li) detector with source foils enriched to 97% $^{100}\mathrm{Mo}$. After 0.2664 mole years of exposure, we report a 1\ensuremath{\sigma} lower limit on the half-life for the ${\mathit{J}}^{\mathit{P}}$=${0}^{+}$\ensuremath{\rightarrow}${0}^{+}$ transition of 0.44\ifmmode\times\else\texttimes\fi{}${10}^{23}$ years.

The pionic x-ray energies of the $4f\ensuremath{-}3d$ transition in $\ensuremath{\pi}$-P and the $5f\ensuremath{-}4d$ transition in $\ensuremath{\pi}$-Ti were measured with a bent-crystal spectrometer at the Nevis synchrocyclotron; and a new value of the pionic mass is deduced to be 139 567.5\ifmmode\pm\else\textpm\fi{}0.9 keV, leading to an improved value for the $\ensuremath{\mu}$-neutrino mass of ${{m}_{{\ensuremath{\nu}}_{\ensuremath{\mu}}}}^{2}$=0.102\ifmmode\pm\else\textpm\fi{}0.119 ${\mathrm{MeV}}^{2}$; ${m}_{{\ensuremath{\nu}}_{\ensuremath{\mu}}}l0.52$ MeV, at 90% confidence level.

Measurements of the absolute neutron yield and the time dependence of the appearance of neutrons resulting from muon-catalyzed fusion have been carried out in high-density deuterium-tritium mixtures. The temperature dependence of the resonant dt..mu..-molecular formation process has been determined in the range 100 to 540 K. Mesomolecular formation is found to be resonant for DT as well as D/sub 2/ target molecules. The sticking probability and other fundamental parameters have been measured for the first time.

A newly designed, large-aperture and high-resolution bent-crystal spectrometer has been used to observe high-intensity sources of pionic x rays. The pionic x-ray source was a target of natural titanium which was placed adjacent to a copper pion-production target in the external beam of the Nevis synchrocyclotron. The energy difference between the 5g ..-->.. 4f and 5f ..-->.. 4d transitions in pionic titanium was measured to be 87.6 +- 1.8 eV. Comparison with the prediction of the Klein-Gordon equation is made.

We report the results of an experimental search for neutrinoless double-{beta} decay using isotopically enriched foils of {sup 100}Mo interleaved in a stack of 40 silicon detectors. With an exposure of 69.9 mole days, we place lower half-life limits on the {ital J}{sup {ital P}}=0{sup +}{r arrow}0{sup +} transition of 4{times}10{sup 21} yr (68% C.L.) and on the 0{sup +}{r arrow}2{sup +} transition of 4{times}10{sup 20} yr (68% C.L.).

New experimental results on muon-catalyzed d-t fusion are reported. Unexpected target-density effects have been discovered both in dt\ensuremath{\mu} molecular formation in t\ensuremath{\mu}+${\mathrm{D}}_{2}$ collisions and in the effective sticking probability. The dt\ensuremath{\mu} formation rate is significantly enhanced at high density, presumably because of a strong three-body contribution. The origin of the observed reduction of the sticking probability at high density remains unclear. Both effects increase the number of fusions per muon that can be achieved; 150\ifmmode\pm\else\textpm\fi{}4(stat.)\ifmmode\pm\else\textpm\fi{}20(syst.) fusions per muon have been observed.