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.
Abstract 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 $$^{100}$$ 100 Mo to the ground state of $$^{100}$$ 100 Ru, ...$$T_{1/2} = \left 6.81 \pm 0.01\,\left( \text{ stat }\right) ^{+0.38}_{-0.40}\,\left( \text{ syst }\right) \right \times 10^{18}$$ T1/2=6.81±0.01stat-0.40+0.38syst×1018 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 $$5\times 10^5$$ 5×105 events and a signal-to-background ratio of $$\sim $$ ∼ 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 $$\mathrm{n}=2,3,7$$ 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 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.
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
.
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 .
Spectral modeling of scintillator for the NEMO-3 and SuperNEMO detectors Argyriades, J.; Arnold, R.; Augier, C. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
2011, 2011-1-00, 20110101, 2011-01-01, Letnik:
625, Številka:
1
Journal Article
Recenzirano
Odprti dostop
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
207Bi 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.
Cross sections, angular distributions and forward-backward asymmetries are presented, of two-fermion events produced in e+e- collisions at centre-of-mass energies from 189 to 209 GeV at LEP, measured ...with the ALEPH detector. Results for e+e-, μ+μ-, τ+τ-, qq̄, bb̄ and cc̄ production are in agreement with the standard model predictions. Constraints are set on scenarios of new physics such as four-fermion contact interactions, leptoquarks, Z′ bosons, TeV-scale quantum gravity and R-parity violating squarks and sneutrinos.
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