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The NEMO-3 results for the double- β decay of 150 Nd to the 0 1 + and 2 1 + excited states of 150 Sm are reported. The data recorded during 5.25 year with 36.6 g of the isotope 150 Nd are used in the analysis. The signal of the 2 ν β β transition to the 0 1 + excited state is detected with a statistical significance exceeding 5 σ . The half-life is measured to be T 1 / 2 2 ν β β ( 0 1 + ) = 1 . 11 - 0.14 + 0.19 stat - 0.15 + 0.17 syst × 10 20  year, which is the most precise value that has been measured to date. 90% confidence-level limits are set for the other decay modes. For the 2 ν β β decay to the 2 1 + level the limit is T 1 / 2 2 ν β β ( 2 1 + ) > 2.42 × 10 20 year . The limits on the 0 ν β β decay to the 0 1 + and 2 1 + levels of 150 Sm are significantly improved to T 1 / 2 0 ν β β ( 0 1 + ) > 1.36 × 10 22 year and T 1 / 2 0 ν β β ( 2 1 + ) > 1.26 × 10 22 year .

The NEMO-3 results for the double- β decay of¹⁵⁰ Nd to the 0 ⁺₁and 2 ⁺₁excited states of¹⁵⁰ Sm are reported. The data recorded during 5.25 year with 36.6 g of the isotope¹⁵⁰ Nd are used in the analysis. The signal of the2ν β β transition to the 0 ⁺₁excited state is detected with a statistical significance exceeding 5 σ . The half-life is measured to beT_(1/2)^(2ν β β)(0⁺₁) = \\left[ 1.11 ^(+0.19)_(-0.14) \\left( \\hbox stat\\right) ^(+0.17)_(-0.15) \\left( \\hbox syst\\right) \\right] × 10²⁰  year, which is the most precise value that has been measured to date. 90% confidence-level limits are set for the other decay modes. For the2ν β β decay to the 2 ⁺₁level the limit isT^(2ν β β)_(1/2)(2⁺₁) > 2.42 × 10²⁰ \\hbox year . The limits on the0ν β β decay to the 0 ⁺₁and 2 ⁺₁levels of¹⁵⁰ Sm are significantly improved toT_(1/2)^(0ν β β)(0⁺₁) > 1.36 × 10²² \\hbox yearandT_(1/2)^(0ν β β)(2⁺₁) > 1.26 × 10²² \\hbox year .

The NEMO-3 results for the double-$$\\beta $$β decay of$$^{150}$$150 Nd to the 0$$^+_1$$1 + and 2$$^+_1$$1 + excited states of$$^{150}$$150 Sm are reported. The data recorded during 5.25 year with 36.6 g of the isotope$$^{150}$$150 Nd are used in the analysis. The signal of the$$2\\nu \\beta \\beta $$2 ν β β transition to the 0$$^+_1$$1 + excited state is detected with a statistical significance exceeding 5$$\\sigma $$σ . The half-life is measured to be$$T_{1/2}^{2\\nu \\beta \\beta }(0^+_1) = \\left[ 1.11 ^{+0.19}_{-0.14} \\,\\left( \\hbox {stat}\\right) ^{+0.17}_{-0.15}\\,\\left( \\hbox {syst}\\right) \\right] \\times 10^{20}$$T 1 / 2 2 ν β β ( 0 1 + ) = 1 . 11 - 0.14 + 0.19 stat - 0.15 + 0.17 syst × 10 20  year, which is the most precise value that has been measured to date. 90% confidence-level limits are set for the other decay modes. For the$$2\\nu \\beta \\beta $$2 ν β β decay to the 2$$^+_1$$1 + level the limit is$$T^{2\\nu \\beta \\beta }_{1/2}(2^+_1) > 2.42 \\times 10^{20}~\\hbox {year}$$T 1 / 2 2 ν β β ( 2 1 + ) > 2.42 × 10 20 year . The limits on the$$0\\nu \\beta \\beta $$0 ν β β decay to the 0$$^+_1$$1 + and 2$$^+_1$$1 + levels of$$^{150}$$150 Sm are significantly improved to$$T_{1/2}^{0\\nu \\beta \\beta }(0^+_1) > 1.36 \\times 10^{22}~\\hbox {year}$$T 1 / 2 0 ν β β ( 0 1 + ) > 1.36 × 10 22 year and$$T_{1/2}^{0\\nu \\beta \\beta }(2^+_1) > 1.26 \\times 10^{22}~\\hbox {year}$$T 1 / 2 0 ν β β ( 2 1 + ) > 1.26 × 10 22 year .

Abstract The NEMO-3 results for the double-β β decay of¹⁵⁰150 Nd to the 0⁺₁1 + and 2⁺₁1 + excited states of¹⁵⁰150 Sm are reported. The data recorded during 5.25 year with 36.6 g of the isotope¹⁵⁰150 Nd are used in the analysis. The signal of the2ν β β 2 ν β β transition to the 0⁺₁1 + excited state is detected with a statistical significance exceeding 5σ σ . The half-life is measured to beT_(1/2)^(2ν β β)(0⁺₁) = \\left[ 1.11 ^(+0.19)_(-0.14) \\left( \\hbox stat\\right) ^(+0.17)_(-0.15) \\left( \\hbox syst\\right) \\right] × 10²⁰T 1 / 2 2 ν β β ( 0 1 + ) = 1 . 11 - 0.14 + 0.19 stat - 0.15 + 0.17 syst × 10 20  year, which is the most precise value that has been measured to date. 90% confidence-level limits are set for the other decay modes. For the2ν β β 2 ν β β decay to the 2⁺₁1 + level the limit isT^(2ν β β)_(1/2)(2⁺₁) > 2.42 × 10²⁰ \\hbox yearT 1 / 2 2 ν β β ( 2 1 + ) > 2.42 × 10 20 year . The limits on the0ν β β 0 ν β β decay to the 0⁺₁1 + and 2⁺₁1 + levels of¹⁵⁰150 Sm are significantly improved toT_(1/2)^(0ν β β)(0⁺₁) > 1.36 × 10²² \\hbox yearT 1 / 2 0 ν β β ( 0 1 + ) > 1.36 × 10 22 year andT_(1/2)^(0ν β β)(2⁺₁) > 1.26 × 10²² \\hbox yearT 1 / 2 0 ν β β ( 2 1 + ) > 1.26 × 10 22 year .

The SuperNEMO Demonstrator, designed to search for double beta decay using enriched 82Se, has been assembled in the Modane Underground Laboratory under the French Alps. Thin foils with radio - purified and enriched 82Se are installed centrally in the detector. A novel foil fabrication method has been developed, improving the radiopurity achieved in the previous generation experiment. It consists of wrapping standalone selenium pads in raw Mylar, combined with selenium purified by a new reverse-chromatography method. This paper describes the features of these foils, their fabrication process, the characterization results, and the integration of the foils into the SuperNEMO Demonstrator.

The SuperNEMO experiment is searching for neutrinoless double beta decay of \\textsuperscript{82}Se, with the unique combination of a tracking detector and a segmented calorimeter. This feature allows to detect the two electrons emitted in the decay and measure their individual energy and angular distribution. The SuperNEMO calorimeter consists of 712 plastic scintillator blocks readout by large PMTs. After the construction of the demonstrator calorimeter underground, we have performed its first commissioning using \\(\\gamma\\)-particles from calibration sources or from the ambient radioactive background. This article presents the quality assurance tests of the SuperNEMO demonstrator calorimeter and its first time and energy calibrations, with the associated methods.

The performance of Hamamatsu 8\" photomultiplier tubes (PMTs) of the type used in the SuperNEMO neutrinoless double-beta decay experiment (R5912-MOD), is investigated as a function of exposure to helium (He) gas. Two PMTs were monitored for over a year, one exposed to varying concentrations of He, and the other kept in standard atmospheric conditions as a control. Both PMTs were exposed to light signals generated by a Bi-207 radioactive source that provided consistent large input PMT signals similar to those that are typical of the SuperNEMO experiment. The energy resolution of PMT signals corresponding to 1 MeV energy scale determined from the Bi-207 decay spectrum, shows a negligible degradation with He exposure; however the rate of after-pulsing shows a clear increase with He exposure, which is modelled and compared to diffusion theory. A method for reconstructing the partial pressure of He within the PMT and a method for determining the He breakdown point, are introduced. The implications for long-term SuperNEMO operations are briefly discussed.

The SuperNEMO experiment is searching for neutrinoless double beta decay of \\textsuperscript{82}Se, with the unique combination of a tracking detector and a segmented calorimeter. This feature allows to detect the two electrons emitted in the decay and measure their individual energy and angular distribution. The SuperNEMO calorimeter consists of 712 plastic scintillator blocks readout by large PMTs. After the construction of the demonstrator calorimeter underground, we have performed its first commissioning using \\(\\gamma\\)-particles from calibration sources or from the ambient radioactive background. This article presents the quality assurance tests of the SuperNEMO demonstrator calorimeter and its first time and energy calibrations, with the associated methods.

The NEMO-3 results for the double-\\(\\) decay of \\(^150\\)Nd to the 0\\(^+_1\\) and 2\\(^+_1\\) excited states of \\(^150\\)Sm are reported. The data recorded during 5.25 yr with 36.6 g of the isotope \\(^150\\)Nd are used in the analysis. For the first time, the signal of the \\(2\\) transition to the 0\\(^+_1\\) excited state is detected with a statistical significance exceeding 5\\(\\). The half-life is measured to be \\(T_1/2^2(0^+_1) = [ 1.11 ^+0.19_-0.14 \\,(stat) ^+0.17_-0.15\\, (syst) ] 10^20\\,yr\\). The limits are set on the \\(2\\) decay to the 2\\(^+_1\\) level and on the \\(0\\) decay to the 0\\(^+_1\\) and 2\\(^+_1\\) levels of \\(^150\\)Sm.