Cadmium tungstate crystal scintillators enriched in 106 Cd ( 106 CdWO 4 ) and 116 Cd ( 116 CdWO 4 ) have been developed to search for 2β-decay of 106 Cd and 116 Cd.
The double-beta decay of \(^{116}\)Cd has been investigated with the help of radiopure enriched \(^{116}\)CdWO\(_4\) crystal scintillators (mass of 1.162 kg) at the Gran Sasso underground laboratory. ...The half-life of \(^{116}\)Cd relatively to the \(2\nu2\beta\) decay to the ground state of \(^{116}\)Sn was measured with the highest up-to-date accuracy as \(T_{1/2}=(2.63^{+0.11}_{-0.12})\times10^{19}\) yr. A new improved limit on the 0\(\nu\)2\(\beta\) decay of \(^{116}\)Cd to the ground state of \(^{116}\)Sn was set as \(T_{1/2}\geq 2.2 \times 10^{23}\) yr at 90\% C.L., which is the most stringent known restriction for this isotope. It corresponds to the effective Majorana neutrino mass limit in the range \(\langle m_\nu\rangle\le(1.0-1.7)\) eV, depending on the nuclear matrix elements used in the estimations. New improved half-life limits for the 0\(\nu\)2\(\beta\) decay with majoron(s) emission, Lorentz-violating \(2\nu2\beta\) decay and \(2\beta\) transitions to excited states of \(^{116}\)Sn were set at the level of \(T_{1/2}\geq 10^{20}-10^{22}\) yr. New limits for the hypothetical lepton-number violating parameters (right-handed currents admixtures in weak interaction, the effective majoron-neutrino coupling constants, R-parity violating parameter, Lorentz-violating parameter, heavy neutrino mass) were set.
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.
Phys. Rev. D 95, 012007 (2017) The NEMO-3 experiment measured the half-life of the $2\nu\beta\beta$ decay
and searched for the $0\nu\beta\beta$ decay of $^{116}$Cd. Using $410$ g of
$^{116}$Cd ...installed in the detector with an exposure of $5.26$ y,
($4968\pm74$) events corresponding to the $2\nu\beta\beta$ decay of $^{116}$Cd
to the ground state of $^{116}$Sn have been observed with a signal to
background ratio of about $12$. The half-life of the $2\nu\beta\beta$ decay has
been measured to be $
T_{1/2}^{2\nu}=2.74\pm0.04\mbox{(stat.)}\pm0.18\mbox{(syst.)}\times10^{19}$
y. No events have been observed above the expected background while searching
for $0\nu\beta\beta$ decay. The corresponding limit on the half-life is
determined to be $T_{1/2}^{0\nu} \ge 1.0 \times 10^{23}$ y at the $90$ % C.L.
which corresponds to an upper limit on the effective Majorana neutrino mass of
$\langle m_{\nu} \rangle \le 1.4-2.5$ eV depending on the nuclear matrix
elements considered. Limits on other mechanisms generating $0\nu\beta\beta$
decay such as the exchange of R-parity violating supersymmetric particles,
right-handed currents and majoron emission are also obtained.
Neutrinoless double-beta decay is a key process in particle physics. Its experimental investigation is the only viable method that can establish the Majorana nature of neutrinos, providing at the ...same time a sensitive inclusive test of lepton number violation. CROSS (Cryogenic Rare-event Observatory with Surface Sensitivity) aims at developing and testing a new bolometric technology to be applied to future large-scale experiments searching for neutrinoless double-beta decay of the promising nuclei \(^{100}\)Mo and \(^{130}\)Te. The limiting factor in large-scale bolometric searches for this rare process is the background induced by surface radioactive contamination, as shown by the results of the CUORE experiment. The basic concept of CROSS consists of rejecting this challenging background component by pulse-shape discrimination, assisted by a proper coating of the faces of the crystal containing the isotope of interest and serving as energy absorber of the bolometric detector. In this paper, we demonstrate that ultra-pure superconductive Al films deposited on the crystal surfaces act successfully as pulse-shape modifiers, both with fast and slow phonon sensors. Rejection factors higher than 99.9% of \(\alpha\) surface radioactivity have been demonstrated in a series of prototypes based on crystals of Li\(_2\)MoO\(_4\) and TeO\(_2\). We have also shown that point-like energy depositions can be identified up to a distance of \(\sim 1\) mm from the coated surface. The present program envisions an intermediate experiment to be installed underground in the Canfranc laboratory (Spain) in a CROSS-dedicated facility. This experiment, comprising \(\sim 3\times 10^{25}\) nuclei of \(^{100}\)Mo, will be a general test of the CROSS technology as well as a worldwide competitive search for neutrinoless double-beta decay, with sensitivity to the effective Majorana mass down to 70 meV in the most favorable conditions.
The double beta decay of \(^{150}\)Nd to the first excited 0\(^+\) level of \(^{150}\)Sm (\(E_{exc}\) = 740.5 keV) has been investigated with the help of the ultra-low-background setup consisting of ...four HP Ge (high-purity germanium) detectors (\({\approx}\) 225 cm\(^3\) volume each one) at the Gran Sasso underground laboratory of INFN (Italy). A highly purified 2.381-kg sample of neodymium oxide (Nd\(_2\)O\(_3\)) was used as a source of \({\gamma}\) quanta expected in the decays. Gamma quanta with energies 334.0 keV and 406.5 keV emitted after deexcitation of the \(0_1^+\) 740.5 keV level of \(^{150}\)Sm are observed in the coincidence spectra accumulated over 16375 h. The half-life relatively to the two neutrino double beta decay \(^{150}\)Nd \(\rightarrow\) \(^{150}\)Sm(0\(_1^+\)) is measured as \(T_{1/2} = 4.7_{-1.9}^{+4.1}\text{(stat)} {\pm} 0.5\text{(syst)} {\times} 10^{19} y\), in agreement with results of previous experiments.
The dynamics of formation, reproduction, and recognition of trace conditioned reflexes to positive and differentiation stimuli was studied on subjects of 15-17 years old. Formation and reproduction ...of such reflexes was found to occur under a close interaction of both levels of the higher nervous activity--recognized and unrecognized levels. Recognized reactions prevailed on unrecognized ones in cases of involvement of active attention. On the basis of this fact, the formation and reproduction of trace conditioned reflexes to positive stimuli has been supposed to occur with an active participation of the left hemisphere. The right hemisphere apparently plays a leading role in formation and reproduction of trace conditioned reflexes to differention stimuli to which the attention of the subjects was not fixed.
