Session Y18: Sterile Neutrino Searches

Live

The three-detector Short Baseline Neutrino (SBN) program, consisting of the SBND, MicroBooNE, and ICARUS detectors, will search for oscillations of neutrinos from the Booster Neutrino Beam at Fermilab. SBN will be sensitive to muon-neutrino disappearance and electron-neutrino appearance, facilitating searches for eV-mass scale sterile neutrinos in the region of parameter space motivated by the LSND and MiniBooNE anomalies. The CAFAna fitting framework was developed in the context of the NOvA experiment and can be used to fit simulated SBN data with a “3+1” sterile neutrino model. We will demonstrate the sensitivity, including the impact of systematic uncertainty, of the three-detector SBN program to eV-mass scale sterile neutrino oscillation using the CAFAna fitting framework.   

Live

We introduce a renormalizable and anomaly-free $U(1)^\prime$ gauge extension of the standard model, and show that it can provide a consistent explanation of a number of prominent low energy anomalies. We show that the simultaneous presence of all portal connections between a neutral dark sector and the SM lead to unique phenomenological signatures at experiment. We further discuss these signatures and the ongoing effort to search for these classes of models, in particular, as a solution to the MiniBooNE low energy excess.   

Not Participating

The Heavy Unseen Neutrino Total Energy Reconstruction (HUNTER) collaboration is developing a method to detect sterile neutrinos at the keV level. This sterile neutrino could complete the neutrino family, while interacting with other standard neutrinos via a much lower coupling strength. HUNTER is developing a method of measuring the vector momentum of all decay products involved in the subsequent K-capture events of the beta decay of atoms suspended in a magneto-optical trap. Non-conservation of momentum would constitute a keV range sterile neutrino. Detection of the mono-energetic x-rays, 32-36 keV, act as a trigger for the successive measurement of the remaining decay products. The current stage of development for the x-ray detection method will be presented.   

Live

Following a successful physics run at the underground LNGS laboratory in Italy, the 760-ton ICARUS T600 liquid argon time-projection chamber underwent a significant overhaul at CERN and has been moved to the Fermi National Accelerator Laboratory (FNAL).~ At FNAL it will be the far detector in the Short-Baseline Neutrino (SBN) program, which is devoted to addressing observed neutrino measurement anomalies and the potential existence of sterile neutrinos. In this talk, I will present the status of the upgraded ICARUS detector and the timeline for the SBN program.   

Live

When a cosmic ray particle collides with the upper atmosphere, it creates a shower of particles that transverse down to the Earth's surface. These cosmogenic particles provide a challenging background in neutrino experiments. The ICARUS detector is a Liquid Argon Time Projection Chamber (LArTPC) that is part of a program dedicated to solve the sterile neutrino anomaly. As this detector will operate at shallow depth, it is exposed to a high flux of cosmic rays that could fake a neutrino interaction. The ICARUS detector will employ two techniques to mitigate this cosmogenic exposure: installing a 3-meter-thick concrete overburden to reduce the flux and a Cosmic Ray Tagging (CRT) system that will surround the LArTPC and tag incoming particles. The cosmogenic background suppression provided by the overburden is explored using simulated events with a detailed detector description. In this talk, I will present a study of the effect the concrete overburden has on stopping particles before they reach the ICARUS cryostat.   

Live

PROSPECT, the Precision Reactor Oscillation and SPECTrum experiment, is a reactor antineutrino experiment consisting of a segmented liquid scintillator antineutrino detector designed to probe short-baseline neutrino oscillations and precisely measure the antineutrino spectrum of the primary fission isotope U-235 from the High Flux Isotope Reactor (HFIR) at Oak Ridge National Laboratory (ORNL). PROSPECT uses a 4-ton optically segmented, Li6-loaded liquid scintillator detector with high light yield, world-leading energy resolution, and excellent pulse shape discrimination. PROSPECT’s neutrino oscillation analysis looks for differences in measured inverse beta decay (IBD) positron spectra at different positions in its detector. With a current baseline coverage of between 7 and 9 meters, the analysis search for sterile oscillations in the ~1-10 $eV^2$ mass-splitting range, with sensitivities largely independent of the underlying reactor antineutrino flux. We’ll talk about PROSPECT’s most recent measurement of the energy spectrum of U235 neutrino and we will also summarize PROSPECT’s latest oscillation analysis results.   

Live

Discrepancies in the reactor antineutrino flux and spectrum between experimental measurements and models suggest possible oscillations involving a sterile neutrino, and/or misunderstanding of neutrino production in nuclear reactors. PROSPECT, the Precision Reactor Oscillation and Spectrum experiment, investigates these discrepancies by measuring antineutrino spectra at a range of short baselines from the $^{235}$U-enriched High Flux Isotope Reactor at Oak Ridge National Laboratory. PROSPECT has operated a 4-ton segmented $^6$Li-loaded liquid scintillator detector, where each end of all longitudinal segments is coupled to a photomultiplier tube (PMT). However, a subset of PMTs were unable to operate during the entire data acquisition period. Therefore, PROSPECT results to date have excluded data from some segments. In this presentation, we describe the calibration and reconstructions procedure using information from segments with a single functional PMT in the PROSPECT analysis. We will also describe the expected improvement in sensitivity of PROSPECT physics measurements that can be achieved using single ended event reconstruction.   

Live

Searches for heavy neutral lepton production in K$^{\mathrm{+}}\to $e$^{\mathrm{+}}$N and K$^{\mathrm{+}}\to \mu^{\mathrm{+}}$N decays using the data set collected by the NA62 experiment at CERN in 2016-18 are presented. Upper limits on the elements of the extended neutrino mixing matrix [U$_{\mathrm{e4}}$]$^{\mathrm{2}}$ and [U$_{\mathrm{\mu 4}}$]$^{\mathrm{2\thinspace }}$are established at the levels of 10$^{\mathrm{-9}}$ and 10$^{\mathrm{-8}}$, respectively, improving on the earlier searches for heavy neutral lepton production and decays in the kinematically accessible mass range.   

Live

IsoDAR@KamLAND is a proposed short baseline $\overline\nu_e$ disappearance experiment designed to search for eV-scale sterile neutrinos. In a 5-year run period, IsoDAR will produce more than $10^{23}\ \overline\nu_e$ through decay-at-rest of $^8Li$, produced in a high-power target bombarded by 60 MeV protons. Paired with a kiloton-scale detector such as KamLAND, IsoDAR can cover the regions favored by short baseline anomalies with a 5-$\sigma$ confidence level in 5 years.  If a signal is observed, IsoDAR will be able to distinguish between several sterile neutrino models.  IsoDAR@KamLAND is also capable of precision electroweak measurements through $\overline\nu_e - e $ elastic scattering. Here we briefly describe the setup, and in detail the physics of the sterile neutrino search that is possible with IsoDAR. We also touch on the electroweak measurements and possibilities for the IsoDAR cyclotron beyond KamLAND.