93 research outputs found
Measurement of the 2νββ decay half-life of 150Nd and a search for 0νββ decay processes with the full exposure from the NEMO-3 detector
We present results from a search for neutrinoless double-β (0νββ) decay using 36.6 g of the isotope
150Nd with data corresponding to a live time of 5.25 y recorded with the NEMO-3 detector. We construct a
complete background model for this isotope, including a measurement of the two-neutrino double-β decay
half-life of T2ν
1=2 ¼ ½9.34 0.22ðstatÞ þ0.62 −0.60 ðsystÞ × 1018 y for the ground state transition, which represents
the most precise result to date for this isotope. We perform a multivariate analysis to search for 0νββ decays
in order to improve the sensitivity and, in the case of observation, disentangle the possible underlying decay
mechanisms. As no evidence for 0νββ decay is observed, we derive lower limits on half-lives for several mechanisms involving physics beyond the standard model. The observed lower limit, assuming light
Majorana neutrino exchange mediates the decay, is T0ν
1=2 > 2.0 × 1022 y at the 90% C.L., corresponding to
an upper limit on the effective neutrino mass of hmνi < 1.6–5.3 eV
The HITRAN2020 molecular spectroscopic database
The HITRAN database is a compilation of molecular spectroscopic parameters. It was established in the early 1970s and is used by various computer codes to predict and simulate the transmission and emission of light in gaseous media (with an emphasis on terrestrial and planetary atmospheres). The HITRAN compilation is composed of five major components: the line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, experimental infrared absorption cross-sections (for molecules where it is not yet feasible for representation in a line-by-line form), collision-induced absorption data, aerosol indices of refraction, and general tables (including partition sums) that apply globally to the data. This paper describes the contents of the 2020 quadrennial edition of HITRAN. The HITRAN2020 edition takes advantage of recent experimental and theoretical data that were meticulously validated, in particular, against laboratory and atmospheric spectra. The new edition replaces the previous HITRAN edition of 2016 (including its updates during the intervening years). All five components of HITRAN have undergone major updates. In particular, the extent of the updates in the HITRAN2020 edition range from updating a few lines of specific molecules to complete replacements of the lists, and also the introduction of additional isotopologues and new (to HITRAN) molecules: SO, CH3F, GeH4, CS2, CH3I and NF3. Many new vibrational bands were added, extending the spectral coverage and completeness of the line lists. Also, the accuracy of the parameters for major atmospheric absorbers has been increased substantially, often featuring sub-percent uncertainties. Broadening parameters associated with the ambient pressure of water vapor were introduced to HITRAN for the first time and are now available for several molecules. The HITRAN2020 edition continues to take advantage of the relational structure and efficient interface available at www.hitran.org and the HITRAN Application Programming Interface (HAPI). The functionality of both tools has been extended for the new edition
Measurement of the 2 nu beta beta decay half-life and search for the 0 nu beta beta decay of Cd-116 with the NEMO-3 detector
The NEMO-3 experiment measured the half-life of the
2
ν
β
β
decay and searched for the
0
ν
β
β
decay of
116
Cd
. Using 410 g of
116
Cd
installed in the detector with an exposure of 5.26 y, (
4968
±
74
) events corresponding to the
2
ν
β
β
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
ν
β
β
decay has been measured to be
T
2
ν
1
/
2
=
[
2.74
±
0.04
(
stat
)
±
0.18
(
syst
)
]
×
1
0
19
y
. No events have been observed above the expected background while searching for
0
ν
β
β
decay. The corresponding limit on the half-life is determined to be
T
0
ν
1
/
2
≥
1.0
×
1
0
23
y
at the 90% C.L. which corresponds to an upper limit on the effective Majorana neutrino mass of
⟨
m
ν
⟩
≤
1.4
–
2.5
eV
depending on the nuclear matrix elements considered. Limits on other mechanisms generating
0
ν
β
β
decay such as the exchange of R-parity violating supersymmetric particles, right-handed currents and majoron emission are also obtained
Final results on ⁸²Se double beta decay to the ground state of ⁸²Kr from the NEMO-3 experiment
Using data from the NEMO-3 experiment, we have measured the two-neutrino double beta decay ( 2\nu \beta \beta) half-life of ^{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} 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. In addition, a search for neutrinoless double beta decay ( 0\nu \beta \beta) using 0.93 kg of ^{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. }) 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 }, where the range reflects 0\nu \beta \beta nuclear matrix element values from different calculations. Furthermore, constraints on lepton number violating parameters for other 0\nu \beta \beta mechanisms, such as right-handed currents, majoron emission and R-parity violating supersymmetry modes have been set
Calorimeter development for the SuperNEMO double beta decay experiment
SuperNEMO is a double-β decay experiment, which will employ the successful tracker–calorimeter technique used in the recently completed NEMO-3 experiment. SuperNEMO will implement 100 kg of double-β decay isotope, reaching a sensitivity to the neutrinoless double-β decay (0νββ) half-life of the order of 1026 yr, corresponding to a Majorana neutrino mass of 50–100 meV. One of the main goals and challenges of the SuperNEMO detector development programme has been to reach a calorimeter energy resolution, ΔE∕E, around 3%∕E(MeV) σ, or 7%∕E(MeV) FWHM (full width at half maximum), using a calorimeter composed of large volume plastic scintillator blocks coupled to photomultiplier tubes. We describe the R&D programme and the final design of the SuperNEMO calorimeter that has met this challenging goal
Search for Neutrinoless Quadruple-beta Decay of Nd-150 with the NEMO-3 Detector
We report the results of a first experimental search for lepton number violation by four units
in the neutrinoless quadruple-β decay of 150Nd using a total exposure of 0.19 kg·y recorded with
the NEMO-3 detector at the Modane Underground Laboratory (LSM). We find no evidence of this
decay and set lower limits on the half-life in the range T1/2 > (1.1–3.2) × 1021 y at the 90% CL,
depending on the model used for the kinematic distributions of the emitted electrons
Measurement of the beta beta Decay Half-Life of Te-130 with the NEMO-3 Detector
We report results from the NEMO-3 experiment based on an exposure of 1275 days with 661 g of Te-130 in the form of enriched and natural tellurium foils. The beta beta decay rate of Te-130 is found to be greater than zero with a significance of 7.7 standard deviations and the half-life is measured to be T-1/2(2v)=[7.0 +/- 0.9(stat) +/- 1: 1(syst)] x 10(20) yr. This represents the most precise measurement of this half- life yet published and the first real-time observation of this decay
Mathematical model of oil-containing water purification process in the volume of granulated media
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