M. Bongrand

Measurement of the Double Beta Decay Half-life of Nd-150 and Search for Neutrinoless Decay Modes with the NEMO-3 Detector

The half-life for double-{beta} decay of {sup 150}Nd has been measured by the NEMO-3 experiment at the Modane Underground Laboratory. Using 924.7 days of data recorded with 36.55 g of {sup 150}Nd, we measured the half-life for 2{nu}{beta}{beta} decay to be T{sub 1/2}{sup 2{nu}}=(9.11{sub -0.22}{sup +0.25}(stat.){+-}0.63(syst.))x10{sup 18} yr. The observed limit on the half-life for neutrinoless double-{beta} decay is found to be T{sub 1/2}{sup 0{nu}}>1.8x10{sup 22} yr at 90% confidence level. This translates into a limit on the effective Majorana neutrino mass of <4.0-6.3 eV if the nuclear deformation is taken into account. We also set limits on models involving Majoron emission, right-handed currents, and transitions to excited states.

Measurement of double beta decay of Mo-100 to excited states in the NEMO 3 experiment

The double beta decay of 100Mo to the 0^+_1 and 2^+_1 excited states of 100Ru is studied using the NEMO 3 data. After the analysis of 8024 h of data the half-life for the two-neutrino double beta decay of 100Mo to the excited 0^+_1 state is measured to be T^(2nu)_1/2 = [5.7^{+1.3}_{-0.9}(stat)+/-0.8(syst)]x 10^20 y. The signal-to-background ratio is equal to 3. Information about energy and angular distributions of emitted electrons is also obtained. No evidence for neutrinoless double beta decay to the excited 0^+_1 state has been found. The corresponding half-life limit is T^(0nu)_1/2(0^+ -->0^+_1)>8.9 x 10^22 y (at 90% C.L.). The search for the double beta decay to the 2^+_1 excited state has allowed the determination of limits on the half-life for the two neutrino mode T^(2nu)_1/2(0^+ -->2^+_1)>1.1 x 10^21 y (at 90% C.L.) and for the neutrinoless mode T^(0nu)_1/2(0^+ -->2^+_1)>1.6 x 10^23 y (at 90% C.L.).

Search for neutrinoless double-beta decay of

We report the results of a search for the neutrinoless double-β decay (0νββ) of Mo100, using the NEMO-3 detector to reconstruct the full topology of the final state events. With an exposure of 34.7  kg·y, no evidence for the 0νββ signal has been found, yielding a limit for the light Majorana neutrino mass mechanism of T1/2(0νββ)>1.1×1024 years (90% C.L.) once both statistical and systematic uncertainties are taken into account. Depending on the nuclear matrix elements this corresponds to an upper limit on the Majorana effective neutrino mass of ⟨mν⟩<0.3–0.9  eV (90% C.L.). Constraints on other lepton number violating mechanisms of 0νββ decays are also given. Searching for high-energy double electron events in all suitable sources of the detector, no event in the energy region [3.2–10] MeV is observed for an exposure of 47  kg·y.

^{100}Mo

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.

with the NEMO-3 detector

The development of BiPo detectors is dedicated to the measurement of extremely high radiopurity in

Measurement of the Double Beta Decay Half-life of 130Te with the NEMO-3 Detector

^{208}

Results of the BiPo-1 prototype for radiopurity measurements for the SuperNEMO double beta decay source foils

Tl and

Measurement of the Double-Beta Decay Half-Life and Search for the Neutrinoless Double-Beta Decay of

^{214}

^{48}{\rm Ca}

Bi for the SuperNEMO double beta decay source foils. A modular prototype, called BiPo-1, with 0.8

with the NEMO-3 Detector

m^2