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 Formula omittedMo to the ground state of Formula omittedRu, Formula omitted ...year. The two-electron energy sum, single electron energy spectra and distribution of the angle between the electrons are presented with an unprecedented statistics of Formula omitted events and a signal-to-background ratio of Formula omitted 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 Formula omitted, 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 NEMO-3 results for the double-
β
decay of
150
Nd to the 0
1
+
and 2
1
+
excited states of
150
Sm are reported. The data recorded during 5.25 year with 36.6 g of the isotope
150
Nd are used in the ...analysis. The signal of the
2
ν
β
β
transition to the 0
1
+
excited state is detected with a statistical significance exceeding 5
σ
. The half-life is measured to be
T
1
/
2
2
ν
β
β
(
0
1
+
)
=
1
.
11
-
0.14
+
0.19
stat
-
0.15
+
0.17
syst
×
10
20
year, which is the most precise value that has been measured to date. 90% confidence-level limits are set for the other decay modes. For the
2
ν
β
β
decay to the 2
1
+
level the limit is
T
1
/
2
2
ν
β
β
(
2
1
+
)
>
2.42
×
10
20
year
. The limits on the
0
ν
β
β
decay to the 0
1
+
and 2
1
+
levels of
150
Sm are significantly improved to
T
1
/
2
0
ν
β
β
(
0
1
+
)
>
1.36
×
10
22
year
and
T
1
/
2
0
ν
β
β
(
2
1
+
)
>
1.26
×
10
22
year
.
Using data from the NEMO-3 experiment, we have measured the two-neutrino double beta decay ( Formula omitted) half-life of Formula omittedSe as Formula omitted y under the single-state dominance ...hypothesis for this nuclear transition. The corresponding nuclear matrix element is Formula omitted. In addition, a search for neutrinoless double beta decay ( Formula omitted) using 0.93 kg of Formula omittedSe observed for a total of 5.25 y has been conducted and no evidence for a signal has been found. The resulting half-life limit of Formula omitted for the light neutrino exchange mechanism leads to a constraint on the effective Majorana neutrino mass of Formula omitted, where the range reflects Formula omitted nuclear matrix element values from different calculations. Furthermore, constraints on lepton number violating parameters for other Formula omitted mechanisms, such as right-handed currents, majoron emission and R-parity violating supersymmetry modes have been set.
Technology is constantly evolving in more sophisticated forms giving new opportunities for educators to transfer learning into virtual space. New educational technology trends are associated today ...with blended learning where traditional methods of teaching merge with online sessions. Blended learning with its learner-centered approach has a potential to enhance the quality of teaching and learning. Russian higher institutions embrace this technology as a strategy to engage and motivate students and thereby augment the learning process. The paper studies students’ engagement and satisfaction with the online courses and their overall perception from learners’ perspective. The findings could serve as a reference point to promote online courses and to achieve considerable educational benefits.
Abstract The NEMO-3 results for the double- $$\beta $$ β decay of $$^{150}$$ 150 Nd to the 0 $$^+_1$$ 1 + and 2 $$^+_1$$ 1 + excited states of $$^{150}$$ 150 Sm are reported. The data recorded during ...5.25 year with 36.6 g of the isotope $$^{150}$$ 150 Nd are used in the analysis. The signal of the $$2\nu \beta \beta $$ 2 ν β β transition to the 0 $$^+_1$$ 1 + excited state is detected with a statistical significance exceeding 5 $$\sigma $$ σ . The half-life is measured to be $$T_{1/2}^{2\nu \beta \beta }(0^+_1) = \left 1.11 ^{+0.19}_{-0.14} \,\left( \hbox {stat}\right) ^{+0.17}_{-0.15}\,\left( \hbox {syst}\right) \right \times 10^{20}$$ T 1 / 2 2 ν β β ( 0 1 + ) = 1 . 11 - 0.14 + 0.19 stat - 0.15 + 0.17 syst × 10 20 year, which is the most precise value that has been measured to date. 90% confidence-level limits are set for the other decay modes. For the $$2\nu \beta \beta $$ 2 ν β β decay to the 2 $$^+_1$$ 1 + level the limit is $$T^{2\nu \beta \beta }_{1/2}(2^+_1) > 2.42 \times 10^{20}~\hbox {year}$$ T 1 / 2 2 ν β β ( 2 1 + ) > 2.42 × 10 20 year . The limits on the $$0\nu \beta \beta $$ 0 ν β β decay to the 0 $$^+_1$$ 1 + and 2 $$^+_1$$ 1 + levels of $$^{150}$$ 150 Sm are significantly improved to $$T_{1/2}^{0\nu \beta \beta }(0^+_1) > 1.36 \times 10^{22}~\hbox {year}$$ T 1 / 2 0 ν β β ( 0 1 + ) > 1.36 × 10 22 year and $$T_{1/2}^{0\nu \beta \beta }(2^+_1) > 1.26 \times 10^{22}~\hbox {year}$$ T 1 / 2 0 ν β β ( 2 1 + ) > 1.26 × 10 22 year .
Technical design and performance of the NEMO 3 detector Arnold, R.; Augier, C.; Bakalyarov, A.M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2005, 2005-1-00, Letnik:
536, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The development of the Neutrino Ettore Majorana Observatory (NEMO
∼
3
) detector, which is now running in the Fréjus Underground Laboratory (L.S.M. Laboratoire Souterrain de Modane), was begun more ...than ten years ago. The NEMO 3 detector uses a tracking-calorimeter technique in order to investigate double beta decay processes for several isotopes. The technical description of the detector is followed by the presentation of its performance.
The double-beta decay of 82Se to the 01+ excited state of 82Kr has been studied with the NEMO-3 detector using 0.93 kg of enriched 82Se measured for 4.75 y, corresponding to an exposure of 4.42 kg⋅y. ...A dedicated analysis to reconstruct the γ-rays has been performed to search for events in the 2e2γ channel. No evidence of a 2νββ decay to the 01+ state has been observed and a limit of T1/22ν(Se82,0gs+→01+)>1.3×1021y at 90% CL has been set. Concerning the 0νββ decay to the 01+ state, a limit for this decay has been obtained with T1/20ν(Se82,0gs+→01+)>2.3×1022y at 90% CL, independently from the 2νββ decay process. These results are obtained for the first time with a tracko-calo detector, reconstructing every particle in the final state.
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
=
6.81
±
0.01
stat
-
0.40
+
...0.38
syst
×
10
18
year. 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
×
10
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.
Abstract Using data from the NEMO-3 experiment, we have measured the two-neutrino double beta decay ($$2\nu \beta \beta $$ 2νββ ) half-life of $$^{82}$$ 82 Se as $$T_{\smash {1/2}}^{2\nu } \!=\! ...\left 9.39 \pm 0.17\left( \text{ stat }\right) \pm 0.58\left( \text{ syst }\right) \right \times 10^{19}$$ T1/22ν=9.39±0.17stat±0.58syst×1019 y under the single-state dominance hypothesis for this nuclear transition. The corresponding nuclear matrix element is $$\left| M^{2\nu }\right| = 0.0498 \pm 0.0016$$ M2ν=0.0498±0.0016 . In addition, a search for neutrinoless double beta decay ($$0\nu \beta \beta $$ 0νββ ) using 0.93 kg of $$^{82}$$ 82 Se observed for a total of 5.25 y has been conducted and no evidence for a signal has been found. The resulting half-life limit of $$T_{1/2}^{0\nu } > 2.5 \times 10^{23} \,\text{ y } \,(90\%\,\text{ C.L. })$$ T1/20ν>2.5×1023y(90%C.L.) for the light neutrino exchange mechanism leads to a constraint on the effective Majorana neutrino mass of $$\langle m_{\nu } \rangle < \left( 1.2{-}3.0\right) \,\text{ eV }$$ ⟨mν⟩<1.2-3.0eV , where the range reflects $$0\nu \beta \beta $$ 0νββ nuclear matrix element values from different calculations. Furthermore, constraints on lepton number violating parameters for other $$0\nu \beta \beta $$ 0νββ mechanisms, such as right-handed currents, majoron emission and R-parity violating supersymmetry modes have been set.
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