Search results for "neutriino"
showing 10 items of 83 documents
Direct determination of the atomic mass difference of the pairs 76As−76Se and 155Tb−155Gd rules out 76As and 155 Tb as possible candidates for electr…
2022
The first direct determination of the ground-state–to–ground-state Q values of the β− decay 76As→76Se and the electron-capture decay 155Tb→155Gd was performed utilizing the double Penning trap mass spectrometer JYFLTRAP. By measuring the atomic mass difference of the decay pairs via the phase-imaging ion-cyclotron-resonance technique, the Q values of 76As→76Se and 155Tb→155Gd were determined to be 2959.265(74) keV and 814.94(18) keV, respectively. The precision was increased relative to earlier measurements by factors of 12 and 57, respectively. The new Q values are 1.33 keV and 5 keV lower compared to the values adopted in the most recent Atomic Mass Evaluation 2020. With the newly determi…
Challenges in double charge exchange measurements for neutrino physics
2019
The neutrinoless double beta (0νββ) decay, if observed, has important implications on particle physics, cosmology and fundamental physics. In particular it can give access to the effective neutrino mass. In order to extract such information from the 0νββ-decay half-life measurement, the knowledge of the Nuclear Matrix Elements (NME) is of utmost importance. In this context the NUMEN and the NURE projects aim to extract information on the NME by measuring the Double Charge Exchange (DCE) reaction cross section in selected systems of interest for the 0νββ-decay. The experimental difficulties that have to be faced are the measurements at very forward-angle, the very low cross section of the pr…
Optimizing the θ23 octant search in long baseline neutrino experiments
2017
Determination of the θ 23 octant will be an important goal for the next generation of neutrino oscillation experiments, as it will show whether the true value of θ 23 lies in the high octant, θ 23 > 45°, or in the low octant, θ 23 < 45°. In this work we investigate the prospects of studying the θ 23 octant in future long baseline neutrino experiments. Using the GLoBES software, we study the sensitivity to θ 23 octant in terms of baseline length and beam sharing and use the LBNO setup as our benchmark. We also show the interference on the octant determination that arises from the unconstrained CP violation angle δ CP. In our results, we show the impact of matter effects on the octant determi…
Search for Neutrinoless Quadruple-β Decay of 150Nd with the NEMO-3 Detector
2017
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 yr recorded with the NEMO-3 detector at the Modane Underground Laboratory. We find no evidence of this decay and set lower limits on the half-life in the range T1/2>(1.1–3.2)×10^21 yr at the 90% C.L., depending on the model used for the kinematic distributions of the emitted electrons. peerReviewed
Numerical studies on neutrino oscillation physics in long baseline experiments
2018
This thesis examines the prospects of future long baseline neutrino oscillation experiments. Using computer simulation techniques, we calculate the experimental sensitivities for two experimental configurations in a set of important questions which are all relevant for modern day neutrino physics. First, we set focus on the determination of the θ23 octant, where the aim is to find whether the atmospheric neutrino mixing angle θ23 lies in the high octant, θ23 > 45◦, or in the low octant, θ23 < 45◦. On the other hand, we study how well the long baseline experiments could test the limits of the Standard Model by seeking deviations from the oscillation patterns that follow from the standard three…
Optimization of the JUNO liquid scintillator composition using a Daya Bay antineutrino detector
2021
To maximize the light yield of the liquid scintillator (LS) for the Jiangmen Underground Neutrino Observatory (JUNO), a 20 t LS sample was produced in a pilot plant at Daya Bay. The optical properties of the new LS in various compositions were studied by replacing the gadolinium-loaded LS in one antineutrino detector. The concentrations of the fluor, PPO, and the wavelength shifter, bis-MSB, were increased in 12 steps from 0.5 g/L and 0.01 mg/L to 4 g/L and 13 mg/L, respectively. The numbers of total detected photoelectrons suggest that, with the optically purified solvent, the bis-MSB concentration does not need to be more than 4 mg/L. To bridge the one order of magnitude in the detector s…
Search for the double-beta decay of 82Se to the excited states of 82Kr with NEMO-3
2020
The double-beta decay of 82Se to the 0+1 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 gamma-rays has been performed to search for events in the 2e2g channel. No evidence of a 2nbb decay to the 0+1 state has been observed and a limit of T2n 1/2(82Se; 0+gs -> 0+1) > 1.3 1021 y at 90% CL has been set. Concerning the 0nbb decay to the 0+1 state, a limit for this decay has been obtained with T0n 1/2(82Se; 0+g s -> 0+1) > 2.3 1022 y at 90% CL, independently from the 2nbb decay process. These results are obtained for the first time with a tracko-…
Deep Underground Neutrino Experiment (DUNE) Near Detector Conceptual Design Report
2021
The Deep Underground Neutrino Experiment (DUNE) is an international, world-class experiment aimed at exploring fundamental questions about the universe that are at the forefront of astrophysics and particle physics research. DUNE will study questions pertaining to the preponderance of matter over antimatter in the early universe, the dynamics of supernovae, the subtleties of neutrino interaction physics, and a number of beyond the Standard Model topics accessible in a powerful neutrino beam. A critical component of the DUNE physics program involves the study of changes in a powerful beam of neutrinos, i.e., neutrino oscillations, as the neutrinos propagate a long distance. The experiment co…
High-Precision Q-Value Measurement Confirms the Potential of 135Cs for Absolute Antineutrino Mass Scale Determination
2020
The ground-state-to-ground-state β-decay Q value of Cs135(7/2+)→Ba135(3/2+) has been directly measured for the first time. The measurement was done utilizing both the phase-imaging ion-cyclotron resonance technique and the time-of-flight ion-cyclotron resonance technique at the JYFLTRAP Penning-trap setup and yielded a mass difference of 268.66(30) keV between Cs135(7/2+) and Ba135(3/2+). With this very small uncertainty, this measurement is a factor of 3 more precise than the currently adopted Q value in the Atomic Mass Evaluation 2016. The measurement confirms that the first-forbidden unique β--decay transition Cs135(7/2+)→Ba135(11/2-) is a candidate for antineutrino mass measurements wit…
Momentum distributions of cosmic relics: Improved analysis
2022
We solve coupled momentum-dependent Boltzmann equations for the phase space distribution of cosmic relic particles, without resorting to approximations of assuming kinetic equilibrium or neglecting backscattering or elastic interactions. Our method is amendable to precision numerical computations. To test it, we consider two benchmark models where the momentum dependence of dark matter distribution function is potentially important: a real singlet scalar extension near the Higgs resonance and a sterile neutrino dark matter model with a singlet scalar mediator. The singlet scalar example shows that the kinetic equilibrium may hold surprisingly well even near sharp resonances. However, the in…