Results from NEMO 3

The NEMO 3 experiment is located in the Modane Underground Laboratory and has been taking data since 2003 with seven isotopes. It is searching for the double beta decay process with two or zero neutrinos emitted in the final state. Precision measurements of the half-life of the isotopes due to two neutrino double beta decay have been performed and new results for 96Zr, 48Ca and 150Nd are presented here. Measurements of this process are important for reducing the uncertainties on the nuclear matrix elements. No evidence for zero neutrino double beta decay has been found and a 90% Confidence Level lower limit on the half-life of this process is derived. From this an upper limit can be set on the effective Majorana neutrino mass using the most recent nuclear matrix elements calculations.Comment: 4 pages, 6 figures, a paper submitted to the proceedings for the conference Neutrino0

Measurement of the double-ss decay half-life and search for the neutrinoless double-ss decay of Ca-48 with the NEMO-3 detector

Neutrinoless double-β decay is a powerful probe of lepton number violating processes that may arise from Majorana terms in neutrino masses, or from supersymmetric, left-right symmetric, and other extensions of the Standard Model. Of the candidate isotopes for the observation of this process, 48Ca has the highest Qββ -value, resulting in decays with energies significantly above most naturally occurring backgrounds. The nucleus also lends itself to precise matrix element calculations within the nuclear shell model. We present the world's best measurement of the two-neutrino double-β decay of 48Ca, obtained by the NEMO-3 collaboration using 5.25 yr of data recorded with a 6.99 g sample of isotope, yielding ≈ 150 events with a signal to background ratio larger than 3. Neutrinoless modes of double-β decay are also investigated, with no evidence of new physics. Furthermore, these results indicate that two-neutrino double-β decay would be the main source of background for similar future searches using 48Ca with significantly larger exposures

Measurement of the beta beta Decay Half-Life of Te-130 with the NEMO-3 Detector

We report results from the NEMO-3 experiment based on an exposure of 1275 days with 661 g of Te-130 in the form of enriched and natural tellurium foils. The beta beta decay rate of Te-130 is found to be greater than zero with a significance of 7.7 standard deviations and the half-life is measured to be T-1/2(2v)=[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

Measurement of the double-beta decay half-life and search for the neutrinoless double-beta decay of Ca48 with the NEMO-3 detector

The NEMO-3 experiment at the Modane Underground Laboratory investigates the double-beta decay of Ca48. Using 5.25 yr of data recorded with a 6.99 g sample of Ca48, approximately 150 double-beta decay candidate events are selected with a signal-to-background ratio greater than 3. The half-life for the two-neutrino double-beta decay of Ca48 is measured to be T2ν1/2=[6.4+0.7−0.6(stat)+1.2−0.9(syst)]×1019  yr. A search for neutrinoless double-beta decay of Ca48 yields a null result, and a corresponding lower limit on the half-life is found to be T0ν1/2>2.0×1022  yr at 90% confidence level, translating into an upper limit on the effective Majorana neutrino mass of ⟨mββ⟩<6.0–26  eV, with the range reflecting different nuclear matrix element calculations. Limits are also set on models involving Majoron emission and right-handed currents.peerReviewe

Search for Neutrinoless Double-Beta Decay of 100^{100}Mo with the NEMO-3 Detector

We report the results of a search for the neutrinoless double-$\beta$ decay (0$\nu\beta\beta$) of $^{100}$Mo, 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 0$\nu\beta\beta$ signal has been found, yielding a limit for the light Majorana neutrino mass mechanism of $T_{1/2}(0\nu\beta\beta)>1.1 \times 10^{24}$ 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 $< 0.3-0.8$ eV (90% C.L.). Constraints on other lepton number violating mechanisms of 0$\nu\beta\beta$ 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

Measurement of the 2νββ decay half-life and search for the 0νββ decay of 116Cd with the NEMO-3 detector

International audienc

Measurement of the 2νββ\nu\beta\beta decay half-life of 150^{150}Nd and a search for 0νββ\nu\beta\beta decay processes with the full exposure from the NEMO-3 detector

We present results from a search for neutrinoless double-β (0νββ) decay using 36.6 g of the isotope Nd150 with data corresponding to a live time of 5.25 y recorded with the NEMO-3 detector. We construct a complete background model for this isotope, including a measurement of the two-neutrino double-β decay half-life of T1/22ν=[9.34±0.22(stat) -0.60+0.62(syst)]×1018  y for the ground state transition, which represents the most precise result to date for this isotope. We perform a multivariate analysis to search for 0νββ decays in order to improve the sensitivity and, in the case of observation, disentangle the possible underlying decay mechanisms. As no evidence for 0νββ decay is observed, we derive lower limits on half-lives for several mechanisms involving physics beyond the standard model. The observed lower limit, assuming light Majorana neutrino exchange mediates the decay, is T1/20ν>2.0×1022  y at the 90% C.L., corresponding to an upper limit on the effective neutrino mass of ⟨mν⟩<1.6–5.3  eV

Standardizing the New E-Business Platform: Learning From the EDI Experience

International audienceThe full data set of the NEMO-3 experiment has been used to measure the half-life of the two-neutrino double beta decay of$^{100}$ Mo to the ground state of$^{100}$ Ru, $T_{1/2} = \left[ 6.81 \pm 0.01\,\left( \text{ stat }\right) ^{+0.38-0.40}\,\left( \text{ syst }\right) \right] \times 10^{18}$  year. The two-electron energy sum, single electron energy spectra and distribution of the angle between the electrons are presented with an unprecedented statistics of $5\times 10^5$ events and a signal-to-background ratio of $\sim$ 80. Clear evidence for the Single State Dominance model is found for this nuclear transition. Limits on Majoron emitting neutrinoless double beta decay modes with spectral indices of $\mathrm{n}=2,3,7$ , as well as constraints on Lorentz invariance violation and on the bosonic neutrino contribution to the two-neutrino double beta decay mode are obtained