Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userFuture Searches for Light Sterile Neutrinos at Nuclear Reactors
71
0
0.0
(
0
)
Ask ChatGPT about the research
No Arabic abstract
We study the optimization of a green-field, two-baseline reactor experiment with respect to the sensitivity for electron antineutrino disappearance in search of a light sterile neutrino. We consider both commercial and research reactors and identify as key factors the distance of closest approach and detector energy resolution. We find that a total of 5 tons of detectors deployed at a commercial reactor with a closest approach of 25 m can probe the mixing angle $sin^22theta$ down to $sim5times10^{-3}$ around $Delta m^2sim 1$ eV$^2$. The same detector mass deployed at a research reactor can be sensitive up to $Delta m^2sim20-30$ eV$^2$ assuming a closest approach of 3 m and excellent energy resolution, such as that projected for the Taishan Antineutrino Observatory (TAO). We also find that lithium doping of the reactor could be effective in increasing the sensitivity for higher $Delta m^2$ values.
rate research
Read More
A considerable experimental effort is currently under way to test the persistent hints for oscillations due to an eV-scale sterile neutrino in the data of various reactor neutrino experiments. The assessment of the statistical significance of these hints is usually based on Wilks theorem, whereby the assumption is made that the log-likelihood is $chi^2$-distributed. However, it is well known that the preconditions for the validity of Wilks theorem are not fulfilled for neutrino oscillation experiments. In this work we derive a simple asymptotic form of the actual distribution of the log-likelihood based on reinterpreting the problem as fitting white Gaussian noise. From this formalism we show that, even in the absence of a sterile neutrino, the expectation value for the maximum likelihood estimate of the mixing angle remains non-zero with attendant large values of the log-likelihood. Our analytical results are then confirmed by numerical simulations of a toy reactor experiment. Finally, we apply this framework to the data of the Neutrino-4 experiment and show that the null hypothesis of no-oscillation is rejected at the 2.6,$sigma$ level, compared to 3.2,$sigma$ obtained under the assumption that Wilks theorem applies.
Neutrino physics is nowadays receiving more and more attention as a possible source of information for the long-standing problem of new physics beyond the Standard Model. The recent measurement of the mixing angle $theta_{13}$ in the standard mixing oscillation scenario encourages us to pursue the still missing results on leptonic CP violation and absolute neutrino masses. However, puzzling measurements exist that deserve an exhaustive evaluation. The NESSiE Collaboration has been setup to undertake conclusive experiments to clarify the muon-neutrino disappearance measurements at small $L/E$, which will be able to put severe constraints to models with more than the three-standard neutrinos, or even to robustly measure the presence of a new kind of neutrino oscillation for the first time. To this aim the use of the current FNAL-Booster neutrino beam for a Short-Baseline experiment has been carefully evaluated. Its recent proposal refers to the use of magnetic spectrometers at two different sites, Near and Far ones. Their positions have been extensively studied, together with the possible performances of two OPERA-like spectrometers. The proposal is constrained by availability of existing hardware and a time-schedule compatible with the undergoing project of a multi-site Liquid-Argon detectors at FNAL. The experiment to be possibly setup at Booster will allow to definitively clarify the current $ u_{mu}$ disappearance tension with $ u_{e}$ appearance and disappearance at the eV mass scale.
A future high-luminosity $Z$-factory has the potential to investigate lepton flavour violation. Rare decays such as $Z to ell_1^mp ell_2^pm$ can be complementary to low-energy (high-intensity) observables of lepton flavour violation. Here we consider two extensions of the Standard Model which add to its particle content one or more sterile neutrinos. We address the impact of the sterile fermions on lepton flavour violating $Z$ decays, focusing on potential searches at FCC-ee (TLEP), and taking into account experimental and observational constraints. We show that sterile neutrinos can give rise to contributions to BR($Z to ell_1^mp ell_2^pm$) within reach of the FCC-ee. We discuss the complementarity between a high-luminosity $Z$-factory and low-energy charged lepton flavour violation facilities.
For a long time there were 3 main experimental indications in favor of the existence of sterile neutrinos: $bar{ u_e}$ appearance in the $bar{ u_mu}$ beam in the LSND experiment, $bar{ u_e}$ flux deficit in comparison with theoretical expectations in reactor experiments, and $ u_e$ deficit in calibration runs with radioactive sources in the Ga solar neutrino experiments SAGE and GALEX. All three problems can be explained by the existence of sterile neutrinos with the mass square difference in the ballpark of $1~mathrm{eV^2}$. Recently the MiniBooNE collaboration observed electron (anti)neutrino appearance in the muon (anti)neutrino beams. The significance of the effect reaches 6.0$sigma$ level when combined with the LSND result. Even more recently the NEUTRINO-4 collaboration claimed the observation of $bar{ u_e}$ oscillations to sterile neutrinos with a significance slightly higher than 3$sigma$. If these results are confirmed, New Physics beyond the Standard Model would be required. More than 10 experiments are devoted to searches of sterile neutrinos. Six very short baseline reactor experiments are taking data just now. We review the present results and perspectives of these experiments.
We determine the sensitivities of short-baseline coherent elastic neutrino-nucleus scattering (CE$ u$NS) experiments using a pion decay at rest neutrino source as a probe for nonunitarity in the lepton sector, as expected in low-scale type-I seesaw schemes. We also identify the best configuration for probing light sterile neutrinos at future ton-scale liquid argon CE$ u$NS experiments, estimating the projected sensitivities on the sterile neutrino parameters. Possible experimental setups at the Spallation Neutron Source, Lujan facility and the European Spallation Source are discussed. Provided that systematic uncertainties remain under control, we find that CE$ u$NS experiments will be competitive with oscillation measurements in the long run.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
