0000000000162414
AUTHOR
V.b. Brudanin
Measurement of the background in the NEMO 3 double beta decay experiment
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.
Results of the search for neutrinoless double-βdecay inMo100with the NEMO-3 experiment
The NEMO-3 detector, which had been operating in the Modane Underground Laboratory from 2003 to 2010, was designed to search for neutrinoless double $\beta$ ($0\nu\beta\beta$) decay. We report final results of a search for $0\nu\beta\beta$ 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 $0\nu\beta\beta$ signal region and find no evidence of $0\nu\beta\beta$ decays in the data. The level of observed background in the $0\nu\beta\beta$ signal region $[2.8-3.2]$ MeV is $0.44 \pm 0.13$ counts/yr/kg, and no events are obs…
Spectral modeling of scintillator for the NEMO-3 and SuperNEMO detectors
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.
Search for double-\beta decay of \{106}Cd by using isotopically enriched \{106}CdWO_{4} crystal scintillator
A search for double β processes in 106Cd was carried out at the Gran Sasso National Laboratories of the INFN (Italy) by using a CdWO4 crystal scintillator (mass of 215 g) enriched in 106Cd up to 66%. After 6590 h of data taking, half-life limits on double beta processes in 106Cd were set at level of 1019 −1021 yr. A possible resonant enhancement of the 0ν2ε processes has also been estimated in the framework of the QRPA approach. peerReviewed
Searches for neutrinoless resonant double electron captures at LNGS
Several experiments were performed during last years at underground (3600 m w.e.) Laboratori Nazionali del Gran Sasso (LNGS) of the INFN (Italy) to search for resonant 2$\varepsilon0\nu$ captures in 96Ru, 106Cd, 136Ce, 156Dy, 158Dy, 180W, 184Os, 190Pt with the help of HP Ge semiconductor detectors, and ZnWO4 and 106CdWO4 crystal scintillators. No evidence for r-2$\varepsilon0\nu$ decays was found, and only T_{1/2} limits were established in the range of 10^{14}-10^{21} yr.
Precise measurement of $2\nu\beta\beta$ decay of $^{100}$Mo with the CUPID-Mo detection technology
We report the measurement of the two-neutrino double-beta ($2\nu\beta\beta$) decay of $^{100}$Mo to the ground state of $^{100}$Ru using lithium molybdate (\crystal) scintillating bolometers. The detectors were developed for the CUPID-Mo program and operated at the EDELWEISS-III low background facility in the Modane underground laboratory. From a total exposure of $42.235$ kg$\times$d, the half-life of $^{100}$Mo is determined to be $T_{1/2}^{2\nu}=[7.12^{+0.18}_{-0.14}\,\mathrm{(stat.)}\pm0.10\,\mathrm{(syst.)}]\times10^{18}$ years. This is the most accurate determination of the $2\nu\beta\beta$ half-life of $^{100}$Mo to date. We also confirm, with the statistical significance of $>3\sigm…
Doppler-broadening of gamma rays following muon capture: search for scalar coupling
Abstract A precision measurement of the 277 keV γ ray produced by capturing muons in gaseous oxygen was performed using high-resolution HPGe detectors. The Doppler-broadened shape of this line is sensitive to the possible admixture into muon capture of genuine scalar interaction. This experiment complements, in the muon sector, in principle, similar ones undertaken recently in nuclear β decay. Using a procedure discussed in earlier papers, a fit to the experimental line-shape allowed us to obtain for the recoil–gamma correlation coefficient the value of a 1 2 =0.096±0.041 (95% CL). The available evaluations of the contributing nuclear matrix elements, performed in the impulse approximation …
Search for neutrinoless double-beta decay ofMo100with the NEMO-3 detector
We report the results of a search for the neutrinoless double-$\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$…
Search for double-βdecay processes in106Cd with the help of a106CdWO4crystal scintillator
A search for double $\ensuremath{\beta}$ processes in ${}^{106}$Cd was carried out at the Gran Sasso National Laboratories of the INFN (Italy) with the help of a ${}^{106}$CdWO${}_{4}$ crystal scintillator (215 g) enriched in ${}^{106}$Cd up to 66$%$. After 6590 h of data taking, new improved half-life limits on the double $\ensuremath{\beta}$ decay processes in ${}^{106}$Cd were established at the level of ${10}^{19}$--${10}^{21}$ yr; in particular, ${T}_{1/2}^{2\ensuremath{\nu}\ensuremath{\varepsilon}{\ensuremath{\beta}}^{+}}\ensuremath{\geqslant}2.1\ifmmode\times\else\texttimes\fi{}{10}^{20}$ yr, ${T}_{1/2}^{2\ensuremath{\nu}2{\ensuremath{\beta}}^{+}}\ensuremath{\geqslant}4.3\ifmmode\tim…
Search for double-\beta decay processes in \{106}Cd with the help of a \{106}CdWO_{4} crystal scintillator
A search for double β processes in 106Cd was carried out at the Gran Sasso National Laboratories of the INFN (Italy) with the help of a 106CdWO4 crystal scintillator (215 g) enriched in 106Cd up to 66%. After 6590 h of data taking, new improved half-life limits on the double β decay processes in 106Cd were established at the level of 1019–1021 yr; in particular, T 2νεβ+ 1/2 2.1 × 1020 yr, T 2ν2β+ 1/2 4.3 × 1020 yr, and T 0ν2ε 1/2 1.0 × 1021 yr. The resonant neutrinoless double-electron captures to the 2718-, 2741-, and 2748-keV excited states of 106Pd are restricted to T 0ν2K 1/2 4.3 × 1020 yr, T 0νKL1 1/2 9.5 × 1020 yr, and T 0νKL3 1/2 4.3 × 1020 yr, respectively (all limits at 90% confide…