Detailed studies of $^{100}$Mo two-neutrino double beta decay in NEMO-3
3 Collaboration, R. Arnold, C. Augier, A. S. Barabash, A. Basharina-Freshville, S. Blondel, S. Blot, M. Bongrand, D. Boursette, V. Brudanin, J. Busto, A. J. Caf… 展开作者
3 Collaboration, R. Arnold, C. Augier, A. S. Barabash, A. Basharina-Freshville, S. Blondel, S. Blot, M. Bongrand, D. Boursette, V. Brudanin, J. Busto, A. J. Caffrey, S. Calvez, M. Cascella, C. Cerna, J. P. Cesar, A. Chapon, E. Chauveau, A. Chopra, L. Dawson, D. Duchesneau, D. Durand, R. Dvornický, V. Egorov, G. Eurin, J. J. Evans, L. Fajt, D. Filosofov, R. Flack, X. Garrido, C. Girard-Carillo, H. Gómez, B. Guillon, P. Guzowski, R. Hodák, A. Huber, P. Hubert, C. Hugon, S. Jullian, O. Kochetov, S. I. Konovalov, V. Kovalenko, D. Lalanne, K. Lang, Y. Lemière, T. Le Noblet, Z. Liptak, X. R. Liu, P. Loaiza, G. Lutter, M. Macko, C. Macolino, F. Mamedov, C. Marquet, F. Mauger, A. Minotti, B. Morgan, J. Mott, I. Nemchenok, M. Nomachi, F. Nova, F. Nowacki, H. Ohsumi, G. Oliviéro, R. B. Pahlka, C. Patrick, F. Perrot, A. Pin, F. Piquemal, P. Povinec, P. Přidal, Y. A. Ramachers, A. Remoto, J. L. Reyss, C. L. Riddle, E. Rukhadze, R. Saakyan, A. Salamatin, R. Salazar, X. Sarazin, J. Sedgbeer, Yu. Shitov, L. Simard, F. Šimkovic, A. Smetana, K. Smolek, A. Smolnikov, S. Söldner-Rembold, B. Soulé, I. Štekl, J. Suhonen, C. S. Sutton, G. Szklarz, H. Tedjditi, J. Thomas, V. Timkin, S. Torre, Vl. I. Tretyak, V. I. Tretyak, V. I. Umatov, I. Vanushin, C. Vilela, V. Vorobel, D. Waters, F. Xie, A. Žukauskas
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, $T_{1/2} = \left[ 6.81 \pm 0.01\,\left(\mbox{stat}\right) ^{+0.38}_{-0.40}\,\left(\mbox{syst}\right) \right] \times10^{18}$ y. The two-electron energy sum, single electron energy spectra and distribution of the angle between the electrons are presented with an unprecedented statistics of $5\times10^5$ events and a signal-to-background ratio of ~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 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.
The double beta decay experiment NEMO~3 has been taking data since February 2003. The aim of this experiment is to search for neutrinoless ($0νββ$) decay and investigate two neutrino double beta decay in seven different isotopically enriched samples ($^{100}$Mo, $^{82}$Se, $^{48}$Ca, $^{96}$Zr, $^{116}$Cd, $^{130}$Te and $^{150}$Nd). After analysis of the data corresponding to 3.75 y, no evidence for $0νββ$ decay in the $^{100}$Mo and $^{82}$Se samples was found. The half-life limits at the 90% C.L. are $1.1\cdot 10^{24}$ y and $3.6\cdot 10^{23}$ y, respectively. Additionally for $0νββ$ decay …
NEMO 3 is a currently running experiment to search for the neutrinoless double beta decay and to study the two-neutrino double beta decay with 10kg of enriched isotopes. On the basis of the first two years of data taking, a limit on the neutrinoless decay $T_{1/2}^{0ν} > 5.8\cdot10^{23}$ y at 90% CL was obtained with $^{100}Mo$. The two-neutrino double beta decay half-lives were measured for all seven $ββ$ isotopes located in NEMO 3. New results are obtained for two of these isotopes: $^{48}Ca T_{1/2}^{2ν}=[4.4 ^{+0.5}_{-0.4} (stat) \pm 0.4 (syst)]\cdot10^{19}$ y, $^{96}Zr T_{1/2}^{2ν}=[2.3 \p…
In the double beta decay experiment NEMO~3 a precise knowledge of the background in the signal region is of outstanding importance. This article presents the methods used in NEMO~3 to evaluate the backgrounds resulting from most if not all possible origins. It also illustrates the power of the combined tracking-calorimetry technique used in the experiment.
The double beta decay experiment NEMO~3 has been taking data since February 2003. The aim of this experiment is to search for neutrinoless decay and investigate two neutrino double beta decay in seven different enriched isotopes ($^{100}$Mo,$^{82}$Se, $^{48}$Ca, $^{96}$Zr, $^{116}$Cd, $^{130}$Te and $^{150}$Nd). After analysis of the data corresponding to 693 days, no evidence for $0νββ$ decay in $^{100}$Mo and $^{82}$Se was found. The half-life limits at 90% C.L. are $5.8\cdot 10^{23}$ y and $2.1\cdot 10^{23}$ y, respectively. Using $\sim$ 940 days of data, preliminary results were obtained f…
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 2nubb decay is measured to be T_1/2^2nu = (9.11+0.25_-0.22}(stat.) +- 0.63 (syst.)) x 10^18 years. The observed limit on the half-life for neutrinoless double beta decay is found to be T_1/2^{0nu} > 1.8 x 10^22 years at 90 % Confidence Level. This translates into a limit on the effective Majorana neutrino mass of <m_{neutrino}><4.0-6.3 eV if the nuclear deformation is taken into account. We also…
NEMO 3 is a double beta decay experiment. A part of low background data was analysed, preliminary result on bb2nu decay of 130Te obtained: T_{1/2} = 7.6 \+- 1.5(stat) +- 0.8(syst) * 10^{20} y$. No bb0nu signal was observed: T_{1/2}^{0ν}(100Mo) > 5.8 *10^{23} y and T_{1/2}^{0ν}(82Se) > 2.1 * 10^{23} y (90% C.L.). SuperNEMO project R&D has started.
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.
Double beta decay of $^{100}$Mo to the excited states of daughter nuclei has been studied using a 600 cm$^3$ low-background HPGe detector and an external source consisting of 2588 g of 97.5% enriched metallic $^{100}$Mo, which was formerly inside the NEMO-3 detector and used for the NEMO-3 measurements of $^{100}$Mo. The half-life for the two-neutrino double beta decay of $^{100}$Mo to the excited 0$^+_1$ state in $^{100}$Ru is measured to be $T_{1/2}=[7.5 \pm{0.6}(stat) \pm {0.6}(syst)]\cdot 10^{20}$ yr. For other $(0ν+ 2ν)$ transitions to the 2$^+_1$, 2$^+_2$, 0$^+_2$, 2$^+_3$ and 0$^+_3$ le…
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. The double beta decay rate of 130Te is found to be greater than 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.
Double-beta decays of $^{100}$Mo from the 6.0195-year exposure of a 6.914 kg high-purity sample were recorded by the NEMO-3 experiment that searched for neutrinoless double-beta decays. These ultra-rare transitions to $^{100}$Ru have a half-life of approximately $7\times10^{18}$ years, and have been used to conduct the first ever search for periodic variations of this decay mode. The Lomb-Scargle periodogram technique, and its error-weighted extension, were employed to look for periodic modulations of the half-life. Monte Carlo modeling was used to study the modulation sensitivity of the data …
SuperNEMO is a next-generation double beta decay experiment based on the successful tracking plus calorimetry design approach of the recently stopped NEMO3 experiment. SuperNEMO can study a range of isotopes, but the baseline isotope is $^{82}$Se. The total isotope mass will be 100--200 kg. A sensitivity to a $0νββ$ half-life greater than $10^{26}$ years can be reached which gives access to Majorana neutrino masses of 50--100 meV. Having successfully completed R&D stage the SuperNEMO Collaboration has commenced the construction of the first module, the Demonstrator. The present status of Super…
We report the results of a search for the neutrinoless double-$β$ decay (0$νββ$) 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$νββ$ signal has been found, yielding a limit for the light Majorana neutrino mass mechanism of $T_{1/2}(0νββ)>1.1 \times 10^{24}$ 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 $< m_ν > < 0.3-0.9$ eV (…
Using data from the NEMO-3 experiment, we have measured the two-neutrino double beta decay ($2νββ$) half-life of $^{82}$Se as $T_{1/2}^{2ν} = \left[ 9.39 \pm 0.17\,\left(\mbox{stat}\right) \pm 0.58\,\left(\mbox{syst}\right)\right] \times 10^{19}$ y under the single-state dominance hypothesis for this nuclear transition. The corresponding nuclear matrix element is $\left|M^{2ν}\right| = 0.0498 \pm 0.0016$. In addition, a search for neutrinoless double beta decay ($0νββ$) using 0.93 kg of $^{82}$Se observed for a total of 5.25 y has been conducted and no evidence for a signal has been found. The…
The NEMO-3 experiment at the Modane Underground Laboratory has investigated the double-$β$ decay of $^{48}{\rm Ca}$. Using $5.25$ yr of data recorded with a $6.99\,{\rm g}$ sample of $^{48}{\rm Ca}$, approximately $150$ double-$β$ decay candidate events have been selected with a signal-to-background ratio greater than $3$. The half-life for the two-neutrino double-$β$ decay of $^{48}{\rm Ca}$ has been measured to be $T^{2ν}_{1/2}\,=\,[6.4\, ^{+0.7}_{-0.6}{\rm (stat.)} \, ^{+1.2}_{-0.9}{\rm (syst.)}] \times 10^{19}\,{\rm yr}$. A search for neutrinoless double-$β$ decay of $^{48}{\rm Ca}$ yields…
The background induced by radioactive impurities of $^{208}\rm Tl$ and $^{214}\rm Bi$ in the source of the double beta experiment NEMO-3 has been investigated. New methods of data analysis which decrease the background from the above mentioned contamination are identified. The techniques can also be applied to other double beta decay experiments capable of measuring independently the energies of the two electrons.
In this report I will briefly review the motivation and history of double beta decay search since the first consideration of two neutrino process (2$β(2ν)$) by Maria Goeppert-Mayer in 1935. The first experiments on search for double beta decay in the late of 1940's and beginning of 1950's are considered. It is underlined that for the first time the 2$β(2ν)$ decay has been registered in geochemical experiment with $^{130}$Te in 1950. In direct (counter) experiment this type of decay for the first time has been registered in $^{82}$Se by Michael Moe's group in 1987. Now two neutrino double beta …
The proton-rich nucleus 33Ar has been studied by detailed proton and gamma-ray spectroscopy at the low-energy facility of SPIRAL at GANIL. Proton and gamma-ray singles and coincidence measurements allowed to establish a quasi complete decay scheme of this nucleus. By comparing the proton intensity to different daughter states, tentative spin assignments have been made for some of the states of 33Cl. The Gamow-Teller strength distribution is deduced and compared to shell-model calculations and a quenching factor is determined. States close to the isobaric analogue state are searched for with re…
In an experiment performed at the SPIRAL1 facility of GANIL, the beta decay of 32Ar has been studied by means of the "Silicon Cube" device associated with germanium clover detectors from the EXOGAM array. Beta-delayed protons and gamma rays have been observed and allowed the determination of all relevant decay branches. The Gamow-Teller strength distribution is compared to shell-model calculations and excellent agreement is found. The Fermi strength is inline with expectations. A quasi-complete decay scheme of 32Ar is established.
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 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$\cdot$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 $0.44 …
We report on the first detailed measurements of electron backscattering from plastic scintillator targets, extending our previous work on beryllium and silicon targets. The scintillator experiment posed several additional experimental challenges associated with charging of the scintillator target, and those challenges are addressed in detail. In addition, we quantitatively compare the energy and angular distributions of this data, and our previous data, with electron transport simulations based on the Geant4 and Penelope Monte Carlo simulation codes. The Penelope simulation is found globally t…
Low-energy excited states in 71,73Ni populated via the β decay of 71,73Co were investigated in an experiment performed at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU). Detailed analysis led to the construction of level schemes of 71,73Ni, which are interpreted using systematics and analyzed using shell model calculations. The 5/2- states attributed to the the f5/2 orbital and positive parity 5/2+ and 7/2+ states from the g9/2 orbital have been identified in both 71,73Ni. In 71Ni the location of a 1/2- β-decaying isomer is proposed and limits are s…
High pressure gas detectors offer advantages for the detection of rare events, where background reduction is crucial. For the neutrinoless double beta decay of 136Xe a high pressure xenon gas Time Projection Chamber (TPC) combines a good energy resolution and a detailed topological information of each event. The ionization topology of the double beta decay event of 136Xe in gaseous xenon has a characteristic shape defined by the two straggling electron tracks ending up in two higher ionization charge density blobs. With a properly pixelized readout, this topological information is invaluable t…
A convincing observation of neutrino-less double beta decay (0$ν$DBD) relies on the possibility of operating high energy-resolution detectors in background-free conditions. Scintillating cryogenic calorimeters are one of the most promising tools to fulfill the requirements for a next-generation experiment. Several steps have been taken to demonstrate the maturity of this technique, starting from the successful experience of CUPID-0. The CUPID-0 experiment demonstrated the complete rejection of the dominant alpha background measuring the lowest counting rate in the region of interest for this t…
The $β$ decay of the drip-line nucleus $^{20}$Mg gives important information on resonances in $^{20}$Na, which are relevant for the astrophysical $rp$-process. A detailed $β$ decay spectroscopic study of $^{20}$Mg was performed by a continuous-implantation method. A detection system was specially developed for charged-particle decay studies, giving improved spectroscopic information including the half-life of $^{20}$Mg, the excitation energies, the branching ratios, and the log $ft$ values for the states in $^{20}$Na populated in the $β$ decay of $^{20}$Mg. A new proton branch was observed and…
Beta decay is a well-established and efficient probe of nuclear structure and provides important information also for halo nuclei. Detailed decay studies of near-dripline nuclei are challenging, but are now feasible due to the technical progress during the last decades in isotope production as well as detection capabilities. The halo structure can change the dynamics of the decay process, most noticably when decays proceed directly to continuum states as seems to be the case in beta-delayed deuteron emission, a process only observed until now for the halo nuclei $^6$He and $^{11}$Li. The prono…
A novel practical few-body method is formulated to include isospin symmetry for nuclear halo structures. The method is designed to describe beta decay, where the basic concept of isospin symmetry facilitates a proper understanding. Both isobaric analogue and anti-analogue states are treated. We derive general and explicit formulas for three-body systems using hyperspherical coordinates. The example of the beta decaying $^{11}$Li ($^{9}$Li+$n$+$n$) is chosen as a challenging application for numerical calculations of practical interest. The detailed results are compared to existing experimental …
Recent measurements of the positron energy spectrum obtained from inverse beta decay interactions of reactor electron antineutrinos show an excess in the 4 to 6 MeV region relative to current predictions. First-principle calculations of fission and beta decay processes within a typical pressurized water reactor core identify prominent fission daughter isotopes as a possible origin for this excess. These calculations also predict percent-level substructure in the antineutrino spectrum due to Coulomb effects in beta decay. Precise measurement of this substructure can constrain nuclear reactor ph…
Motivated by non-zero neutrino masses and the possibility of New Physics discovery, a number of experiments search for neutrinoless double beta decay. While hunting for this hypothetical nuclear process, a significant amount of two-neutrino double beta decay data has become available. Although these events are regarded and studied mostly as the background of neutrinoless double beta decay, they can be also used to probe physics beyond the Standard Model. In this paper we show how the presence of right-handed leptonic currents would affect the energy distribution and angular correlation of the …
We present a detailed discussion on neutrinoless double beta decay within a class of left-right symmetric models where neutrino mass originates by natural type-II seesaw dominance. The spontaneous symmetry breaking is implemented with doublets, triplets and bidoublet scalars. The fermion sector is extended with an extra sterile neutrino per generation that helps in implementing the seesaw mechanism. The presence of extra particles in the model exactly cancels type-I seesaw and allows large value for Dirac neutrino mass matrix $M_D$. The key feature of this work is that all the physical masses …
Silicon Drift Detectors, widely employed in high-resolution and high-rate X-ray applications, are considered here with interest also for electron detection. The accurate measurement of the tritium beta decay is the core of the TRISTAN (TRitium Investigation on STerile to Active Neutrino mixing) project. This work presents the characterization of a single-pixel SDD detector with a mono-energetic electron beam obtained from a Scanning Electron Microscope. The suitability of the SDD to detect electrons, in the energy range spanning from few keV to tens of keV, is demonstrated. Experimental measur…
Observation of neutrinoless double beta decay, a lepton number violating process that has been proposed to clarify the nature of neutrino masses, has spawned an enormous world-wide experimental effort. Relating nuclear decay rates to high-energy, beyond the Standard Model (BSM) physics requires detailed knowledge of non-perturbative QCD effects. Using lattice QCD, we compute the necessary matrix elements of short-range operators, which arise due to heavy BSM mediators, that contribute to this decay via the leading order $π^- \to π^+$ exchange diagrams. Utilizing our result and taking advantage…
Theory of inverse beta decay for reactor antineutrinos
Institute of Theoretical Physics, Chinese Academy of Sciences（中国科学院理论物理研究所）；Institute of High Energy Physics, Chinese Academy of Sciences（中国科学院高能物理研究所）；China Center of Advanced Science and Technology（中国高等科学技术中心）
Within the standard three-neutrino framework, the absolute neutrino masses and their ordering (either normal, NO, or inverted, IO) are currently unknown. However, the combination of current data coming from oscillation experiments, neutrinoless double beta decay searches, and cosmological surveys, can provide interesting constraints for such unknowns in the sub-eV mass range, down to O(0.1) eV in some cases. We discuss current limits on absolute neutrino mass observables by performing a global data analysis, that includes the latest results from oscillation experiments, neutrinoless double bet…
