A novel metastable phase of DyGe2.85 synthesised in the AuCu3-structure under high pressure, has been studied by means of the magnetic susceptibility and electrical resistivity measurements (under ...the pressure P ≤ 3.1 GPa), neutron powder diffraction and time-differential γ-γ perturbed angular correlations (TDPAC) using 111Cd nuclear probes. Two distinct phase transitions have been found in this compound as the temperature is lowered. We assign the first transition occurring at the temperature TCDW = 80 K with charge density wave formation and the second transition at TN ≈ 18 K with an antiferromagnetic spiral ordering of Dy magnetic moments, and discuss a close relationship between them.
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.
An interpretation of the deuterium profile measured along the Vostok (East Antarctica) ice core down to 2755 m has been attempted on the basis of the borehole temperature analysis. An inverse problem ...is solved to infer a local “geophysical metronome,” the orbital signal in the surface temperature oscillations expressed as a sum of harmonics of Milankovich periods. By correlating the smoothed isotopic temperature record to the metronome, a chronostratigraphy of the Vostok ice core is derived with an accuracy of ±3.0–4.5 kyr. The developed timescale predicts an age of 241 kyr at a depth of 2760 m. The ratio δD/δTi between deuterium content and cloud temperature fluctuations (at the top of the inversion layer) is examined by fitting simulated and measured borehole temperature profiles. The conventional estimate of the deuterium‐temperature slope corresponding to the present‐day spatial ratio (9 per mil/°C) is confirmed in general. However, the mismatch between modeled and measured borehole temperatures decreases noticeably if we allow surface temperature, responsible for the thermal state of the ice sheet, to undergo more intensive precession oscillations than those of the inversion temperature traced by isotope record. With this assumption, we obtain the long‐term temporal deuterium‐temperature slope to be 5.8–6.5 per mil/°C which implies that the glacial‐interglacial temperature increase over central Antarctica was about 15°C in the surface temperature and 10°C in the inversion temperature. Past variations of the accumulation rate and the corresponding changes in the ice‐sheet surface elevation are simultaneously simulated.
A new multi-detector spectrometer based on Timepix silicon pixel detectors is developed to investigate the 2ν
EC
/
EC
decay of
106
Cd. The detectors have high efficiency for recording two low-energy ...KX radiation quanta emitted during 2ν
EC
/
EC
decay. The ability of pixel detector to identify α, β, and γ particles and precisely localize them allows us to suppress background radiation efficiently. Test measurements for an assembly of two pixel detectors in an underground laboratory were performed. They showed the possibility of using them in the search for the 2ν
EC
/
EC
decay of
106
Cd.
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.
Abstract
The III phase of experiment TGV-2 to search for β
+
β
+
, β+EC, EC/EC decay of
106
Cd was performed at the Modane underground laboratory (LSM, France, 4800 m w.e.). 16 foils (∼23.2 g) of ...enriched
106
Cd were measured using the 32-detector low background HPGe spectrometer TGV-2 during 42500 h. New limit on 2
ν
EC/EC decay of
106
Cd to the ground 0
+
state of
106
Pd - T
1/2
> 7.2 × 10
20
y at 90% C.L was obtained. The limits on 2νβ
+
β
+
, 2νβ+EC decay of
106
Cd, and 2
ν
ECEC decay of
106
Cd to excited states of
106
Pd were significantly improved in comparison with previous phase II of the TGV-2 experiment.
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
.
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