The possibility to probe new physics scenarios of light Majorana neutrino exchange and right-handed currents at the planned next generation neutrinoless double β decay experiment SuperNEMO is discussed. Its ability to study different isotopes and track the outgoing electrons provides the means to discriminate different underlying mechanisms for the neutrinoless double β decay by measuring the decay half-life and the electron angular and energy distributions.a

The NEMO-3 detector, which had been operating in the Modane Underground Laboratory from 2003 to 2010, was designed to search for neutrinoless double-β (0νββ) decay. We report the final results of a search for 0νββ decays with 6.914 kg of 100 Mo using the entire NEMO-3 data set with a detector live time of 4.96 yr, which corresponds to an exposure of 34.3 kg · yr. We perform a detailed study of the expected background in the 0νββ signal region and find no evidence of 0νββ decays in the data. The level of observed background in the 0νββ signal region [2.8-3.2] MeV is 0.44 AE 0.13 counts=yr=kg, and no events are observed in the interval [3.2-10] MeV. We therefore derive a lower limit on the half-life of 0νββ decays in 100 Mo of * Deceased PHYSICAL REVIEW D 92, 072011 (2015) 1550-7998=2015=92 (7)=072011 (23) 072011-1 © 2015 American Physical Society T 1=2 ð0νββÞ > 1.1 × 10 24 yr at the 90% confidence level, under the hypothesis of decay kinematics similar to that for light Majorana neutrino exchange. Depending on the model used for calculating nuclear matrix elements, the limit for the effective Majorana neutrino mass lies in the range hm ν i < 0.33-0.62 eV. We also report constraints on other lepton-number violating mechanisms for 0νββ decays.

The 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,

The half-life for double beta decay of 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 150 Nd the half-life for 2νββ decay is measured to be T 2ν 1/2 = (9.11 +0.25 −0.22 (stat.) ± 0.63 (syst.)) × 10 18 years. The observed limit on the half-life for neutrinoless double beta decay is found to be T 0ν 1/2 > 1.8×10 22 years at 90% Confidence Level. This translates into a limit on the effective Majorana neutrino mass of mν < 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. Experiments studying atmospheric, solar, reactor and accelerator neutrinos have established the existence of neutrino oscillations as a direct evidence for a non-zero neutrino mass. These experiments, however, cannot distinguish between Dirac or Majorana neutrinos. They also provide no information on the absolute neutrino mass scale, since oscillations experiments measure the square of the mass difference between neutrino states. The half-life of neutrinoless double beta decay (0νββ) is inversely proportional to the effective Majorana neutrino mass squared, m ν 2 . Observation of this process would therefore directly constrain the neutrino mass scale and would be unambiguous evidence for the Majorana nature of neutrinos. The 0νββ process also violates lepton number and is therefore a direct probe for physics beyond the standard model of particle physics.The search for neutrinoless double beta decay of neodymium-150 ( 150 Nd) using the NEMO-3 detector is of special interest since 150 Nd is a candidate isotope for SuperNEMO [1], a next generation double beta decay experiment based on the NEMO-3 concept, and the SNO++ experiment at SNOLAB [2]. Its main advan-2 tages are the high Q ββ value for double beta decay, Q ββ = 3.368 MeV, which lies above the typical energies for many background sources, and the large phase space factor. The 2νββ half-life of 150 Nd has previously been measured using a Time Projection Chamber [3,4].The NEMO-3 experiment has been taking data since 2003 in the Modane Underground Laboratory (LSM) located in the Fréjus tunnel at a depth of 4800 m water equivalent. The detector has a cylindrical shape with 20 sectors that contain different isotopes in the form of thin foils with a total surface of about 20 m 2 [5]. In addition to ∼7 kg of 100 Mo and ∼1 kg of 82 Se, the detector contains smaller amounts of other isotopes. The neodymium source foil is composed of Nd 2 O 3 with an enrichement of (91 ± 0.5)%, corresponding to a 150 Nd mass of 36.55 ± 0.10 g. On each side of the foils is a ∼50 cm wide tracking volume comprising a total of 6180 drift cells operated in Geiger mode with helium as drift gas. A 25 Gauss magnetic field created by a solenoid provides charge identification. The calorimeter consists of 1940 plastic scintillators coupled to low radioactivity photomultipliers. For 1 MeV electrons the energy resolutio...

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Using 9.4 g of 96 Zr isotope and 1221 days of data from the NEMO-3 detector corresponding to 0.031 kg·y, the obtained 2νββ decay half-life measurement is T 2ν 1/2 = [2.35 ± 0.14(stat) ± 0.16(syst)] × 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 2ν nuclear matrix element is extracted using the measured 2νββ half-life and is M 2ν = 0.049 ± 0.002. Constraints on 0νββ decay have also been set.

Blot, S., Bongrand, M., Brudanin, V. et al.). (2016) Measurement of the double-beta decay half-life and search for the neutrinoless double-beta decay of Ca48 with the NEMO-3 detector. Physical Review D (Particles, Fields, Gravitation and Cosmology), 93 (11). 112008. Permanent WRAP URL: http://wrap.warwick.ac.uk/85101 Copyright and reuse:The Warwick Research Archive Portal (WRAP) makes this work by researchers of the University of Warwick available open access under the following conditions. Copyright © and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable the material made available in WRAP has been checked for eligibility before being made available.Copies of full items can be used for personal research or study, educational, or not-for-profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. Publisher statement: © 2016 American Physical Society A note on versions:The version presented here may differ from the published version or, version of record, if you wish to cite this item you are advised to consult the publisher's version. Please see the 'permanent WRAP URL' above for details on accessing the published version and note that access may require a subscription. A search for neutrinoless double-beta decay of 48 Ca yields a null result, and a corresponding lower * Deceased.PHYSICAL REVIEW D 93, 112008 (2016) 2470-0010=2016=93(11)=112008 (9) 112008-1 © 2016 American Physical Society limit on the half-life is found to be T 0ν 1=2 > 2.0 × 10 22 yr at 90% confidence level, translating into an upper limit on the effective Majorana neutrino mass of hm ββ i < 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.

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 double beta 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 2ν 1/2 = (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.