Search

An investigation of double beta decay (β+β+, β+/EC, EC/EC) of 106Cd was performed at the Modane underground laboratory (at a water equivalent depth of 4800 m) using a TGV-2 spectrometer with 32 detectors. Evaluation of the experimental data accumulated over 12 400 h of measuring ∼13.6 g of 106Cd with an enrichment of 75% was performed. New limits (at a confidence level of 90%) on the half-lives of the 0νEC/EC resonant decay of 106Cd to the 2741 keV excited state of 106Pd − T1/2 ≥ 1.5 × 1020 y and on 2νEC/EC decay to the ground state of 106Pd (0+ → 0+, g.s.) − T1/2 ≥ 3.9 × 1020 y were obtained. The limits of the 2νEC/EC decay of 106Cd to the 2+, 512 keV and 01+, 1334 keV excited states of 106Pd and 2νβ+β+- and the 2νβ+EC decays of 106Cd to the ground and excited states of 106Pd were improved.

The studies aimed at decreasing the background of the TGV-2 spectrometer have led to constructive changes in the cryostat and increased the sensitivity of the 32-detector spectrometer. New search for 0νEC/EC, 2νEC/EC) decays of 106Cd was started with ∼13.6 g of 106Cd with enrichment of 75%. The evaluation of the experimental data accumulated for 4800 h was performed. Limits (at 90% CL) on the half-lives of 0νEC/EC resonant decay of 106Cd to the 2741 keV excited state of 106Pd (T1/2 ≥ 6.5 × 1019 y) and on t 2νEC/EC decay to the ground state of 106Pd (0+ → 0+, g.s.) (T1/2 ≥ 1.7 × 1020 y) were obtained. The limits on the other branches of 106Cd decay—2νEC/EC decay to the 2+, 512 keV and 01+, 1334 keV excited states of 106Pd and 2νβ+β+ and 2νβ+EC decays of 106Cd to the ground and excited states of 106Pd were improved.

Search for the β+β+, β+ EC, and EC/EC modes of the 106Cd decay was carried out with the TGV-2 (Telescope Germanium Vertical) low-background multidetector spectrometer installed at the Modane underground laboratory (4800 m w.e.). The measured foil samples ∼50 μm thick and 52 mm in diameter were placed between the entrance windows of the neighboring detectors inside the cryostat. The total measurement time for 10 g of 106Cd enriched to 75% was 8687 h. New limits (at the 90% confidence level, CL) were obtained for the 106Cd half-lives against various branches of the decay to the ground state 0+ and excited states 2+ of the 106Pd daughter nucleus. They are T 1/2(2νβ+β+) ≥ 6.0 × 1019 y, and T 1/2(2νβ+ EC) ≥ 5.9 × 1019 y, and T 1/2(2νEC/EC) ≥ 3.0 × 1020 y for the transitions to the 0+ ground state of 106Pd; T 1/2(2νβ+β+) ≥ 5.7 × 1019 y, T 1/2(2νβ+ EC) ≥ 5.9 × 1019 y, and T 1/2(2νEC/EC) ≥ 4.2 × 1019 y for the transitions to the 2+, 512-keV excited state of 106Pd; and T 1/2(2νEC/EC) ≥ 3.1 × 1019 y for the transition to the 0 1 + , 1334-keV excited state of 106Pd.

The first result of the neutrino magnetic moment measurement at the Kalininskaya Nuclear Power Plant (KNPP) with the GEMMA spectrometer is presented. An antineutrino-electron scattering is investigated. A high-purity germanium detector of 1.5 kg placed 13.9 m away from the 3 GW reactor core is used in the spectrometer. The antineutrino flux is $2.73\times 10^{13} \nu_e / cm^2 / s$. The differential method is used to extract the $\nu$-e electromagnetic scattering events. The scattered electron spectra taken in 6200 and 2064 hours for the reactor ON and OFF periods are compared. The upper limit for the neutrino magnetic moment $\mu_\nu < 5.8\times 10^{-11}$ Bohr magnetons at 90{%} CL is derived from the data processing.

The KLL Auger electron spectrum of 88 Sr generated in the EC-decay of 88 Y has been analyzed at the instrumental resolution of 11 eV using a combined electrostatic spectrometer. Energies and relative intensities of the all nine transitions were determined and compared with theoretical predictions. Our value of 12067.3(12) eV measured for the absolute energy of the dominant KL 2 L 3 ( 1 D 2 ) transition was found to be higher by 7.4 eV (i.e., more than 3 σ ) than that one obtained in a measurement with external excitation. The discrepancy indicates substantial influence of the “atomic structure effect” on absolute transition energies in our experiment. Very good agreement of the measured 0.14(3) and predicted 0.12 values for the KL 1 L 2 ( 3 P 0 / 1 P 1 ) Auger transition intensity ratio clearly proved the predicted strong influence of the relativistic effects on the KL 1 L 2 ( 3 P 0 ) transition rate even at Z = 38.

The low energy KLL Auger electrons of neon emitted after EC-decay of 22Na have been investigated with a 4 eV instrumental resolution using an electrostatic spectrometer and a solid state radioactive source. This is the first experimental investigation of the KLL Auger spectrum of neon from the solid state. Relative intensities and energies of all resolved spectrum components were determined. Measured absolute energy of the dominant KL2L3(1D) transition was found to be 824.5(19) eV, i.e. about 20 eV higher than that obtained in experiments with free Ne atoms. Within the experimental uncertainties, no influence of solid state effects on relative intensities of the KLL transitions was found.

The low-background multi-HPGe spectrometer TGV II installed in the Modane Underground Laboratory (France) is described in detail and the results of the background measurements are reported. The spectrometer is focused on the double beta decay measurements with two isotopes—106Cd ( 2 ν EC / EC mode) and 48Ca ( β β mode). A basic summary of the physics of β β decay (especially EC/EC mode) is also given.

A search for double electron capture of 106Cd was performed at the Modane Underground Laboratory (4800 m w.e.) using a low-background and high-sensitivity multidetector spectrometer TGV-2 (Telescope Germanium Vertical). New limits on β+/EC, EC/EC decays of 106Cd were obtained from preliminary calculations of experimental data accumulated for 4800 h of measurement of 10 g of 106Cd with enrichment of 75%. They are \(T_{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}}^{2\nu \beta ^ + EC} \) > 9.1 × 1018 yr, \(T_{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}}^{2\nu {{EC} \mathord{\left/ {\vphantom {{EC} {EC}}} \right. \kern-\nulldelimiterspace} {EC}}} \) > 1.9 × 1019 yr for transitions to the first 2+, 511.9 keV excited state of 106Pd, and \(T_{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}}^{2\nu \beta ^ + EC} \) > 1.3 × 1019 yr, \(T_{{1 \mathord{\left/ {\vphantom {1 2}} \right. \kern-\nulldelimiterspace} 2}}^{2\nu {{EC} \mathord{\left/ {\vphantom {{EC} {EC}}} \right. \kern-\nulldelimiterspace} {EC}}} \) > 6.2 × 1019 yr for transitions to the ground 0+ state of 106Pd. All limits are given at 90% C.L.

KMM, KMN and KNN Auger electron spectra of 111 Cd emitted in EC-decay of 111 In were analyzed at instrumental resolutions of 14 and 21 eV using a combined electrostatic spectrometer. Energies and relative intensities of 26 resolved components were determined and compared with theoretical predictions. For the first time, the predicted intermediate coupling structure of some KMM Auger lines was observed. A structure of the KNN Auger group for Z

Lead tungstate (PbWO4) crystal scintillators are discussed as an active shield and light guides in Cd-116 double-beta decay experiment with Cadmium tungstate (CdWO4) scintillators. Scintillation properties and radioactive contamination of PbWO4 scintillators were investigated. Energy resolution of CdWO4 detector, coupled to PbWO4 light guide, was tested. Efficiency of PbWO4-based active shield to suppress background from the internal contamination of PbWO4 crystals, as well as possible contribution from radioactivity of copper shield and phototubes were calculated. Using of lead tungstate crystal scintillators as high-efficiency 4 pi active shield could allow to build sensitive 2 beta experiment (T-1/2(0 nu 2 beta) similar to 10(26) yr) to search for 0 nu 2 beta decay of Cd-116 with (CdWO4)-Cd-116 crystal scintillators. (c) 2005 Elsevier B.V. All rights reserved.

The CARVEL (CAlcium Research for VEry Low neutrino mass) experiment to search for the double β decay of 48 Ca with the help of enriched 48 CaWO 4 crystal scintillators has been considered. Scintillation properties (energy resolution, α/β ratio, pulse-shape discrimination ability) and radiopurity of CaWO 4 scintillators were studied. Despite rather high radioactive contaminations, the background rate of the CaWO 4 detector in the energy region 3.6–5.4 MeV (energy window of the 48 Ca neutrinoless 2β decay) was reduced down to 0.07 counts/(yr keV kg). With ≈100 kg array of the 48 CaWO 4 crystals the sensitivity of the CARVEL experiment (in terms of the half-life limit for the 0ν2β decay) is estimated as T 1 / 2 0 ν > 10 27 yr. This value corresponds to the neutrino mass constraint m ν

After analysis of 5797 h of data from the detector NEMO3, new limits on neutrinoless double beta decay of Mo-100 (T_{1/2} > 3.1 10^{23} y, 90% CL) and Se-82 (T_{1/2} > 1.4 10^{23} y, 90% CL) have been obtained. The corresponding limits on the effective majorana neutrino mass are: m 1.4 10^{22} y (90% CL) for Mo-100 and T_{1/2}> 1.2 10^{22} y (90%CL) for Se-82. Corresponding bounds on the Majoron-neutrino coupling constant are g < (0.5-0.9) 10^{-4} and < (0.7-1.6) 10^{-4}. Two-neutrino 2b-decay half-lives have been measured with a high accuracy, T_{1/2} Mo-100 = [7.68 +- 0.02(stat) +- 0.54(syst) ] 10^{18} y and T_{1/2} Se-82 = [10.3 +- 0.3(stat) +- 0.7(syst) ] 10^{19} y.

A spectrum of the low energy electrons from the electron capture decay of 67Ga has been analyzed at the instrumental resolution 4, 7, and 14 eV in the region 570–10 400 eV using an electrostatic spectrometer. Energies and relative intensities of the LMM + LMN, KLL, KLM + KLN, and KMM + KMN Auger transitions have been determined with high accuracy and compared with results of available calculations. The measured absolute energies of the dominant KLL and KLM Auger lines have been found to be significantly higher than the semi-empirical values. Generally, worse agreement has been found between measured and calculated transition intensities. Relative intensities of the main spectrum components have been also determined to be: (LMM+LMN)/KLL/(KLM+KLN)/(KMM+KMN)=(27.5±2.3)/(60.1±4.6)/(14.5±1.0)/(1.00±0.07).

The positrons and coincident gamma-rays following the pure Fermi 0(+) --> 0(+) branch of beta(+)-decay in 140 were measured. The Doppler shift of the gamma-quantum observed is sensitive to the beta-neutrino correlation coefficient, which is unity (alpha = 1) in the absence of scalar coupling. The interatomic interaction of recoiling daughters was noticed, which has prevented to obtain an improved result for scalar coupling despite of the excellent statistical accuracy of the measurement. At the same time, it was shown that the method described can be used as a very sensitive and flexible tool to probe the interatomic interactions in matter at the hundred eV energy level. Perspectives in this direction as well as the future angular-correlation experiments aimed to search for scalar coupling in beta-decay are discussed.

The KLL Auger spectrum of 73 Ge from the electron capture decay of 73 As was measured with 7 eV instrumental resolution using a combined electrostatic spectrometer and a source prepared by a gas-chemical method. The energies and relative intensities of all the nine resolved KLL lines were precisely determined. A rather poor agreement was found between the measured KLL transition energies and predictions of the widely used semiempirical calculations. Our relative KLL transition intensities agree only with results of the relativistic calculations in intermediate coupling with configuration interaction. The predicted influence of the relativistic effects on the KL 1 L 2 ( 3 P 0 ) transition rate was also proven.

A 48CaCO3 powder sample containing 20.18 g of 48Ca was measured for 797 h with a 400 cm3 low-background HPGe detector. New limits on decays of 48Ca were obtained. For single beta transitions to 48Sc the limits are equal to 0.71×1020 y, 1.1×1020 y, and 0.82×1020 y for transitions to the ground state, excited 5+ and 4+ states, respectively. The new limits on double beta decay to excited states of 48Ti are equal to 0.47×1020 y, 1.1×1020 y, and 0.90×1020 y for transitions to the first 2+, second 2+ and first 0+ excited states, respectively. All limits are given at the 90% CL.

A precision measurement of the 277 keV γ ray produced by capturing muons in gaseous oxygen was performed using high-resolution HPGe detectors. The Doppler-broadened shape of this line is sensitive to the possible admixture into muon capture of genuine scalar interaction. This experiment complements, in the muon sector, in principle, similar ones undertaken recently in nuclear β decay. Using a procedure discussed in earlier papers, a fit to the experimental line-shape allowed us to obtain for the recoil–gamma correlation coefficient the value of a 1 2 =0.096±0.041 (95% CL). The available evaluations of the contributing nuclear matrix elements, performed in the impulse approximation in the absence of scalar interaction, produce correlation coefficients in disagreement with our result. These evaluations are independent of the induced pseudoscalar coupling and so of the validity of the PCAC hypothesis, but their reliability and model dependence remain to be investigated.

The angular correlations were investigated measuring with high-precision HPGe detectors γ-lines following the ordinary muon capture (OMC) on 28Si and 16O. The Doppler-broadened shapes of these lines are sensitive to the weak couplings as well as to the nuclear matrix elements (NME) of OMC transitions.

Present status of the experiment TGV II is given. The experiment TGV II is devoted to the measurement of double-beta decay of 106Cd and 48Ca. The new HPGe multi-detector TGV spectrometer has been constructed and installed in the Modane underground laboratory (in France). Preliminary results of the first background measurement are presented.

The TGV (Telescope Germanium Vertical) collaboration is interested in the measurement of double-beta decay of 48Ca (TGV I) and 106Cd (TGV II). The background in the experiment TGV I has been suppressed by several methods. One of them was based on distinguishing between electrons and γ-rays due to the different rise time of the signals obtained from semiconductor detector. Two experimental setups have been tested, the first one used a charge-sensitive analog-to-digital converter, while the second one utilized digital oscilloscope. The reduction of the background counting rate (due to γ-rays) in single HPGe detector by a factor of (1.4-3.8) was reached.

Most currently, viable double beta decay experiments require highly enriched isotopic sources. These sources must be extraordinarily free of radioactive contamination. The double beta decay experiment NEMO 3 will study 100Mo, for which physical and chemical purification techniques have been investigated. The success of the chemical purification process is discussed in the context of ultra-low background, high-purity germanium spectrometer measurements.

To be sensitive to an effective Majorana neutrino mass, 〈 m ν 〉, on the order of 0.1 eV, the NEMO 3 double beta (ββ(0ν)) decay experiment requires precise knowledge and control of the backgrounds. The effect of neutrons and γ-rays from the Frejus underground laboratory (LSM, Laboratoire Souterrain de Modane) has been studied during 10 700 h of data collection. The data were taken with a NEMO 2 prototype detector using different shield configurations. Monte Carlo calculations with GEANT/MICAP code and a new library of γ-rays from neutron captures are presented. The implied consequences for the NEMO 3 detector which is under construction are discussed. The neutrinoless double beta decay background induced by neutrons and γ-rays within the LSM will be suppressed to the very suitable level of 0.1 event in a live time of five years given the appropriate shield and magnetic field.

The NEMO-2 tracking detector located in the Frejus Underground Laboratory was designed as a prototype for the NEMO-3 detector and to study different modes of double beta decay. Measurements with 100 Mo, 116 Cd, 82 Se and 96 Zr were carried out. Presented here are the experimental half-life limits on double beta decays for new Majoron emission modes and limits on effective neutrino–Majoron coupling constants.

We describe an improved follow-up of our previous spin-neutrino correlation experiment, where the 1229 and 2171 keV gamma-rays emitted after the 28 Si( μ , ν ) 28 Al(1 + , 2202 keV) reaction were observed by high-resolution HPGe detectors at different angles with respect to the muon spin. In the experiment described here, a magnetic field was used both to select events according to the spin-gamma angle and to measure the residual muon polarization by the muSR method. We further increase the precision of our result making use of new experimental and theoretical information. We obtain for the parameter x ≡ M (2)/ M (−1) the value of x =0.239±0.029, which can be compared to our previous result (Brudanin et al., Nucl. Phys. A 587 (1995) 577) x =0.254±0.034 and to the value x =0.315±0.080 obtained recently at TRIUMF with a different technique. The coupling-constant ratio g P / g A was deduced from the mean value x =0.247±0.027. Using renormalized transition operators calculated recently, we obtained for g P / g A the solution range of −1.0 to +1.3 to be compared to the value of 7 predicted by PCAC for the free nucleon. This result confirms the strong quenching of g P / g A reported earlier.

Present status of experiments TGV I and TGV II is given. The TGV I collaboration has studied the double-beta decay of 48Ca with a low-background and high sensitivity Ge multi-detector spectrometer TGV (Telescope Germanium Vertical). The preliminary results of $${\text{T}}_{{\text{1/2}}}^{{\text{2}}\nu \beta \beta } = (4.2_{ - 1.3}^{ + 3.3} ) \times 10^{19} $$ years and $${\text{T}}_{{\text{1/2}}}^{0\nu \beta \beta } >1.5 \times 10^{21} $$ years (90% CL) for double-beta decay of 48 Ca has been found after the processing of experimental data obtained after 8700 hours of measuring time using approximately 1 gramme of 48Ca. The aim of the experiment TGV II is the development of the experimental methods, construction of spectrometers and measurement of the ββ decay (β+β+, β+/EC, EC/EC) of 106Cd particularly the 2νEC/EC mode. The theoretical description and performance of the TGV II spectrometer are also given.

The decay of 60 min 148g Tb has been studied by means of the Ge(Li) detectors and magnetic spectrometers. Chemically- and mass-separated sources were used. The ψ rays, conversion electrons, positrons and γ−γ coincidences were measured, and 129 γ rays were assigned to the decay of 148g Tb. Multipolarities of 14 transitions in 148Gd were determined. Significantly modified and supplemented decay scheme of 148g Tb which contains 39 excited states in 148Gd up to 5.4 MeV is proposed.

The low-energy electron spectrum from the 57Co decay has been examined in the region from 0 up to 15 keV at instrumental resolution ranging from 2 to 15 eV. Two electrostatic spectrometers and radioactive sources prepared by vacuum evaporation of 57Co onto Al foils were utilized. Relative intensities of the main spectrum components have been obtained as follows: (TSE+LLX+Shake-off)/LMM/KLL/KLM/KMM/K−14.4/L−14.4/MN−14.4=116±12/51±4/59.7±1.8/15.2±0.4/1.15±0.07/49.6±1.5/5.05±0.15/0.79±0.02 where TSE means “true secondary electrons”. Absolute and relative energies of the LMM, KLL, KLM, and KMM Auger transitions in Fe have also been determined, as well as their relative intensities with the exception of the LMM lines, the shapes of which were strongly distorted due to the inelastic electron scattering and probably also chemical effects. From the measured conversion electron lines of the 14.4 keV M1 transition in 57Fe, a transition energy of 14412.8±0.8 eV and the E2 admixture less than 8×10−6 were derived. Relative intensities of both the KL2,3(M4,5N1) Auger line group and the M4,5N1−14.4 conversion line were found to be lower by about 30% for the “oxide” state of decaying 57Co atoms than for the “metallic” state. Pronounced broadenings of narrow spectrum lines have been observed as a consequence of the oxidation of the 57Co sources in the laboratory atmosphere. Natural widths for most of the KLL, KLM, and KMM Auger lines and those of the K, L1, L2, L3, M1, M2, M3 and N1 atomic levels in 57Fe were also determined.

In the double beta decay (ββ) experiment NEMO-2, the 214 Bi radioactivity has been measured as background for the ββ processes. The analysis of the 214 Bi contamination has been performed via the signature of 214 Po alpha decay. This method has been applied to data taken with enriched 100 Mo and 116 Cd sources. At the level of NEMO-2's sensitivity, in a 1.0 mole yr study of enriched material, the contamination of the sources can be measured in the range of 2.0 mBq kg −1 . The effects of deposited contamination by 222 Rn are also discussed and estimated at the level of 0.3 mBq per square meter of source foil. Backgrounds for neutrinoless double beta decay (ββ0v) are deduced from these measurements and the consequences for the higher sensitivity ββ experiment NEMO-3 are drawn.

The presence of a scalar interaction in nuclear beta-decay was studied by measuring the beta-neutrino correlation coefficient alpha in the superallowed pure Fermi beta-transition Ne-18(O+) --> F-18(O+, 1040 keV) (T-1/2 = 1.67 s). The resulting value, i.e. alpha = + 1.06 +/- 0.19 (error quoted at 2 sigma), corresponds to the limit root/C-s/(2) + C-s'(2) less than or equal to 0.29C-v (95%) CL for the scalar coupling constant. (C) 1997 Elsevier Science B.V.

The NEMO-2 tracking detector located in the Frejus Underground Laboratory was designed as a prototype of the detector NEMO-3 to study 0ν and 2ν double-beta decay (ββ) physics. After ten months of nearly continuous running with an enriched cadmium source (0.92 mol·y of116Cd) aββ2ν half-life ofT1/2=(3.75±0.35(stat)±0.21(syst))·1019 y was measured. Limits with 90% CL on the116Cd half-lives of 5.0·1021 y forββ0ν decay and of 1.2·1021 y forββ0νχ0 decay with a Majoron (χ0) were obtained. Theoretical predictions for 0ν and 2ν decays of116Cd are also presented.

From data accumulated over 6140 h with 172 g of enriched molybdenum (1.18 mol yr of $^{100}\mathrm{Mo}$) with the NEMO 2 detector in the Fr\'ejus Underground Laboratory, a clear \ensuremath{\beta}\ensuremath{\beta}2\ensuremath{\nu} signal (1433 events) is observed, leading to a half-life ${\mathit{T}}_{1/2}$=0.95\ifmmode\pm\else\textpm\fi{}0.04(stat)\ifmmode\pm\else\textpm\fi{}0.09(syst) ${10}^{19}$ yr. The experimental two-electron energy spectrum and the two-electron angular distribution are in agreement with the expected ones. Limits for \ensuremath{\beta}\ensuremath{\beta}0\ensuremath{\nu} decays to the ground state, excited states (${2}_{1}^{+}$ and ${0}_{1}^{+}$), and also with Majoron emission are given.

New limits on 48Caβ− and β−β− decays to excited states of 48Ti have been obtained using a 400 cm3 low-background HPGe detector and an external source of 24.558 g enriched CaF2 powder (9.822 g of 48Ca). The limits for β− decay to the 6+ ground state and excited 5+ and 4+ states in 48Sc are 1.6×1020 yr, 2.5×1020 yr, and 1.9×1020 yr at the 90% confidence level. For the β−β− decay to 48Ti, the limits to the first 2+, second 2+, and first 0+ excited states are 1.8×1020 yr, 1.5×1020 yr, and 1.5×1020 yr, again at the 90% confidence level.

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.

We have constructed a GEANT4-based detailed software model of photon transport in plastic scintillator blocks and have used it to study the NEMO-3 and SuperNEMO calorimeters employed in experiments designed to search for neutrinoless double beta decay. We compare our simulations to measurements using conversion electrons from a calibration source of $\rm ^{207}Bi$ and show that the agreement is improved if wavelength-dependent properties of the calorimeter are taken into account. In this article, we briefly describe our modeling approach and results of our studies., Comment: 16 pages, 10 figures

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

In the double beta decay experiment NEMO 3 a precise knowledge of the background in the signal region is of outstanding importance. This article presents the methods used in NEMO 3 to evaluate the backgrounds resulting from most if not all possible origins. It also illustrates the power of the combined tracking-calorimetry technique used in the experiment., The authors would like to thank the Modane Underground Laboratory staff for their technical assistance in running the experiment. Portions of this work were supported by Grants from RFBR (nos. 06-02-16672 and 06-02-72553) and by the Russian Federal Agency for Atomic Energy. We acknowledge support by the Grant Agencies of the Czech Republic (MSM 6840770029, LA305 and LC07050).

International audience; Currently, the TGV collaboration is investigating the two-neutrino double electron capture (2 nu EC/EC) of (106)Cd at the Modane underground laboratory. The study is performed with low-background multi-HPGe detector TGV II, which has been constructed for measurements of the rare processes. The half-life limits of T(1/2) > 2.6 x 10(20) years (for Phase I, 8687 hours) and T(1/2) > 3.6 x 10(20) years (for Phase II, 9003 hours) were obtained for the ground state to ground state 2 nu EC/EC of (106)Cd. The results already allow to rule out some of the previous nuclear structure calculations.

Using 9.4 g of Zr-96 and 1221 days of data from the NEMO-3 detector corresponding to 0.031 kg yr, the obtained 2vbb decay half-life measurement is [2.35 +/- 0.14(stat) +/- 0.16(syst)] x 10^19 yr. Different characteristics of the final state electrons have been studied, such as the energy sum, individual electron energy, and angular distribution. The 2v nuclear matrix element is extracted using the measured 2vbb half-life and is 0.049 +/- 0.002. Constraints on 0vbb decay have also been set., Published in Nucl.Phys.A (10 pages, 10 figures)

The result of the 3-year neutrino magnetic moment measurement at the Kalinin Nuclear Power Plant with the GEMMA spectrometer is presented. Antineutrino-electron scattering is investigated. A high-purity germanium detector of 1.5 kg placed at a distance of 13.9 m from the 3 GW(th) reactor core is used in the spectrometer. The antineutrino flux is 2.7E13 1/scm/s. The differential method is used to extract (nu-e) electromagnetic scattering events. The scattered electron spectra taken in 5184+6798 and 1853+1021 hours for the reactor ON and OFF periods are compared. The upper limit for the neutrino magnetic moment < 3.2E-11 Bohr magneton at 90% CL is derived from the data processing., 4 pages, 4 figures

The first result of the neutrino magnetic moment measurement at the Kalininskaya Nuclear Power Plant (KNPP) with the GEMMAspectrometer is presented. An antineutrino-electron scat tering is investigated. A high-purity germanium detector of 1.5 kg placed 13.9 m away from the 3 GW reactor core is used in the spectrometer. The antineutrino flux is 2.73 � 10 13 � �e/cm 2 /s. The differential method is used to extract the �-e electromagnetic scattering events. The scattered electro n spectra taken in 6200 and 2064 hours for the reactor on and off periods are compared. The upper limit for the neutrino magnetic moment � � < 5.8� 10 11 � B at 90% CL is derived from the data processing.

International audience; Search for double beta decay (β+β+, β+/EC, EC/EC) of 106Cd was performed at the Modane underground laboratory (4800 m w.e.) using a spectrometer TGV-2 with 32 HPGe detectors. New limits on the half-lives of 0vEC/EC resonant decay - T1/2 ≥ 1.6 × 1020 y, and on 2vEC/EC decay of 106Cd − T1/2 ≥ 4.1 × 1020 y (at 90% CL) were obtained from preliminary calculations of experimental data accumulated for 12900 h of measurement of ~13.6 g of 106Cd with enrichment of 75%. The limits on 2vEC/EC decay of 106Cd to the 2+,512 keV and 0+1,1334 keV excited states of 106Pd and on 2vβ+β+ and 2vβ+/EC decay of 106Cd were improved

The TGV II (Telescope Germanium Vertical) facility is a low background spectrometer operated in Modane Underground Laboratory (France). It aims at the study of double beta electron capture of 106Cd. The spectrometer is composed of 32 HPGe planar detectors (total mass of Ge ∼3 kg) interleaved with thin-foil samples made of enriched 106Cd. In 2007 the Phase I of the experiment (1 year measurement) was finished and the new limit on half-life for two-neutrino double electron capture (g.s. → g.s.) of 106Cd was obtained as 3.2 × 1020 years. This limit is significantly higher (by almost three orders of magnitude) than those already published. From December 2007 the Phase II of the experiment continues with more enriched material (13.6 grams instead of 8 grams) and with significantly suppressed background of the cryostat.

Conversion electron and photon measurements with the electrostatic and HPGe spectrometers, respectively, proved the existence of the 7.133+or-0.010 keV transition in 160Ho. The conversion intensity ratios for ten outer subshells agree with predictions for the E1 multipolarity and exclude all other multipolarities with L

International audience; The TGV II (Telescope Germanium Vertical) facility is a low background spectrometer operated in Modane Underground Laboratory. It aims at the study of double electron capture of 106Cd. The spectrometer is composed of 32 HPGe planar detectors interleaved with thin‐foil samples made of Cd‐106 enriched to 75% (total mass about 10 g). In 2006, the main run of phase I (1 year duration) was terminated yielding a new limit on half‐life for two‐neutrino double electron capture (g.s.→g.s.) in 106Cd as 2.0×1020 years. This limit is significantly higher (by almost three orders of magnitude) than those already published. © 2007 American Institute of Physics

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.)., 23 pages, 7 figures, 4 tables, submitted to Nucl. Phys

The NEMO-3 tracking detector is located in the Fr��jus Underground Laboratory. It was designed to study double beta decay in a number of different isotopes. Presented here are the experimental half-life limits on the double beta decay process for the isotopes $^{100}$Mo and $^{82}$Se for different Majoron emission modes and limits on the effective neutrino-Majoron coupling constants. In particular, new limits on "ordinary" Majoron (spectral index 1) decay of $^{100}$Mo ($T_{1/2} > 2.7\cdot10^{22}$ y) and $^{82}$Se ($T_{1/2} > 1.5\cdot10^{22}$ y) have been obtained. Corresponding bounds on the Majoron-neutrino coupling constant are $ < (0.4-1.9) \cdot 10^{-4}$ and $< (0.66-1.7) \cdot 10^{-4}$., 23 pages includind 4 figures, to be published in Nuclear Physics A

Present status of the experiment TGV II which is devoted to the measurement of double-beta decay of 106Cd is given. The low background spectrometer TGV II is installed in the Modane Underground Laboratory and has been running from February 2005 with approx 10 grams of 106Cd enriched at 75%. After an analysis of 3736 hours of experimental data the new improved half-life limit for 2νEC/EC decay of 106Cd (0 g.s. + → 0 g.s. + ) is given as T 1 2/2 > 4.8 × 1019 years (90% CL). The search for 2νEC/EC decay of 106Cd to the excited states of 106Pd allows to determine the limits of the half-lives T 1 2/2 (0 g.s. + → 2 1 + ) > 3.9 × 1019 years (90% CL) and T 1 2/2 (0 g.s. + → 0 1 + ) > 5.8 × 1019 years (90% CL).

Presented by V. Egorov; Gamma-rays following nuclear capture of negative muons in enriched 48Ti, 76Se, 106Cd, as well as natural Se and Cd targets were measured. Time evolution of several gamma-lines allowed to deduce the total μ-capture rates in Ti, Se and Cd isotopes, which are compared to the Primakoff estimate. The data on the partial μ-capture rates will be used for more precise calculation of the 2β-NMEs of 48Ca, 76Se and 106Cd.