We discuss several low-energy backgrounds to sub-GeV dark matter searches, which arise from high-energy particles of cosmic or radioactive origin that interact with detector materials. We focus in particular on Cherenkov radiation, transition radiation, and luminescence or phonons from electron-hole pair recombination, and show that these processes are an important source of backgrounds at both current and planned detectors. We perform detailed analyses of these backgrounds at several existing and proposed experiments based on a wide variety of detection strategies and levels of shielding. We find that a large fraction of the observed single-electron events in the SENSEI 2020 run originate from Cherenkov photons generated by high-energy events in the Skipper Charge Coupled Device, and from recombination photons generated in a phosphorus-doped layer of the same instrument. In a SuperCDMS HVeV 2020 run, Cherenkov photons produced in printed-circuit-boards located near the sensor likely explain the origin of most of the events containing 2 to 6 electrons. At SuperCDMS SNOLAB, radioactive contaminants inside the Cirlex located inside or on the copper side walls of their detectors will produce many Cherenkov photons, which could dominate the low-energy backgrounds. For the EDELWEISS experiment, Cherenkov or luminescence backgrounds are subdominant to their observed event rate, but could still limit the sensitivity of their future searches. We also point out that Cherenkov radiation, transition radiation, and recombination could be a significant source of backgrounds at future experiments aiming to detect dark-matter via scintillation or phonon signals. We also discuss the implications of our results for the development of superconducting qubits and low-threshold searches for coherent neutrino scattering, and comment on design strategies that can be implemented to mitigate these backgrounds.
Adopting neutrino oscillation parameters obtained by Super-Kamiokande, a numerical computer experiment for neutrino events occurring outside the detector, is carried out in the same SK live days, 1645.9 live days, constructing the virtual Super-Kamiokande detector in the computer. The numerical results by the computer experiment could be directly compared with the real SK experimental data. The comparison shows that it is difficult to obtain convincing conclusion on the existence of the neutrino oscillation with specified neutrino oscillation parameters claimed by SK through analysis for neutr…
Dark matter detectors will soon be sensitive to Solar neutrinos via two distinct channels: coherent neutrino-nucleus scattering and neutrino electron elastic scattering. We establish an analysis method for extracting Solar model properties and neutrino properties from these measurements, including the possible effects of sterile neutrinos which have been hinted at by some reactor experiments and cosmological measurements. Even including sterile neutrinos, through the coherent scattering channel a 1 ton-year exposure with a low-threshold Germanium detector could improve on the current measureme…
We discuss the impact of near detectors at a neutrino factory both on standard oscillation and non-standard interaction measurements. Our systematics treatment includes cross section errors, flux errors, and background uncertainties, and our near detector fluxes include the geometry of the neutrino source and the detector. Instead of a specific detector concept, we introduce qualitatively different classes of near detectors with different characteristics, such as near detectors catching the whole neutrino flux (near detector limit) versus near detectors observing a spectrum similar to that of …
The India-based Neutrino Observatory (INO) will host a 50 kt magnetized iron calorimeter (ICAL) detector that will be able to detect muon tracks and hadron showers produced by Charged-Current muon neutrino interactions in the detector. The ICAL experiment will be able to determine the precision of atmospheric neutrino mixing parameters and neutrino mass hierarchy using atmospheric muon neutrinos through earth matter effect. In this paper, we report on the sensitivity for the atmospheric neutrino mixing parameters ($\sin^{2}θ_{23}$ and $|Δm^{2}_{32}|$) for the ICAL detector using the reconstruc…
We show that a very precise neutrino/anti-neutrino event separation is not mandatory to cover the physics program of a low energy neutrino factory and thus non-magnetized detectors like water Cerenkov or liquid Argon detectors can be used. We point out, that oscillation itself strongly enhances the signal to noise ratio of a wrong sign muon search, provided there is sufficiently accurate neutrino energy reconstruction. Further, we argue that apart from a magnetic field, other means to distinguish neutrino from anti-neutrino events (at least statistically) can be explored. Combined with the fac…
I discuss why and how powerful is the two-detector setting in neutrino oscillation experiments. I cover three concrete examples: (1) reactor θ_{13} experiments, (2) T2KK, Tokai-to-Kamioka-Korea two-detector complex for measuring CP violation, determining the neutrino mass hierarchy, and resolving the eight-fold parameter degeneracy, (3) two-detector setting in a neutrino factory at baselines 3000 km and 7000 km for detecting effects of non-standard interactions (NSI) of neutrinos.
The ideal neutrino detector at the neutrino factory should have a mass in the range of 10 kton, provide particle identification to tag the flavor of the incoming neutrino, lepton charge measurement to select the incoming neutrino helicity, good energy resolution to reconstruct the incoming neutrino energy, and be isotropic to equally well reconstruct incoming neutrinos from different baselines (it might be more efficient to build various sources at different baselines, than various detectors). The detector should also be able to reconstruct neutrino event typically below 15 GeV. A detector wit…
We examine the potential of the future medium-baseline reactor neutrino oscillation (MBRO) experiments in studying neutrino wave-packet impact. In our study, we treat neutrinos as wave packets and use the corresponding neutrino flavor transition probabilities. The delocalization, separation and spreading of the wave packets lead to decoherence and dispersion effects, which modify the plane-wave neutrino oscillation pattern, by amounts that depend on the energy uncertainties in the initial neutrino wave packets. We find that MBRO experiments could be sensitive to the wave-packet impact, since t…
A large volume scintillation detector is supposed to install at Baksan neutrino observatory INR RAS at Caucasus. The detector will register all possible neutrino fluxes, but mainly geo-neutrinos. In the article the neutrino fluxes are discussed and expected effects in proposed detector are estimated. The design and construction of such a detector is expected to be a part of all the world similar detectors net that is under construction in modern times.
Non-Standard Neutrino Interactions at a Muon Collider Neutrino Detector
Deutsches Elektronen-Synchrotron DESY（德国电子同步加速器）；Department of Physics and Astronomy, University of California, Irvine（加州大学尔湾分校物理与天文系）；Centre for Cosmology, Particle Physics and Phenomenology (CP3), UCLouvain（天主教鲁汶宇宙学、粒子物理与现象学中心）；Faculty of Physics, University of Warsaw（华沙大学物理系）；Center for Particle Physics Siegen, University of Siegen（锡根大学粒子物理锡根中心）；PITT PACC, Department of Physics and Astronomy, University of Pittsburgh（匹兹堡大学物理与天文系皮特粒子物理与宇宙学中心）
An ultra-large Liquid Argon Time Projection Chamber-based neutrino detector will have the uncommon ability to detect atmospheric tau neutrino events. This paper discusses the most promising modes for identifying charged current tau neutrino interactions, and shows that, with simple kinematic cuts, ~30 tau neutrinos can be isolated in a 100 kt*yr exposure, with greater than 4 sigma significance. This sample is sufficient to perform flux-averaged total cross-section and cross-section shape parameterization measurements -- the first steps toward using tau neutrinos to search for physics beyond th…
We consider the effect of general neutrino interactions (scalar, vector, pseudoscalar, axial vector and tensor) in neutrino-electron scattering at the DUNE near detector. Those interactions can be associated with heavy new physics and their effect is to cause distortions in the recoil spectrum of the electrons. We show that for some cases energy scales up to 9 TeV are accessible after a 5 year run and that current bounds on interaction parameters can be improved by up to an order of magnitude. The full set of general interactions includes the usually considered neutrino-electron non-standard m…
Scintillation light is used in liquid argon (LAr) neutrino detectors to provide a trigger signal, veto information against cosmic rays, and absolute event timing. In this work, we discuss additional opportunities offered by detectors with enhanced sensitivity to scintillation light, that is with light collection efficiencies of about $10^{-3}$. We focus on two key detector performance indicators for neutrino oscillation physics: calorimetric neutrino energy reconstruction and neutrino/antineutrino separation in a non-magnetized detector. Our results are based on detailed simulations, with neut…
There are three parameter degeneracies inherent in the three--neutrino analysis of long--baseline neutrino experiments. We develop a systematic method for determining whether or not a set of measurements in neutrino oscillation appearance experiments with approximately monoenergetic beams can completely resolve these ambiguities. We then use this method to identify experimental scenarios in which the parameter degeneracies may be efficiently resolved. Generally speaking, with two appearance measurements degeneracies can occur over wide areas of the $(δ,θ_{13})$ parameter space; with three meas…
We study the problem of determination of the sign of Delta m^2_{31}, or the neutrino mass hierarchy, through observations of atmospheric neutrinos in future detectors. We consider two proposed detector types : (a) Megaton sized water Cerenkov detectors, which can measure the survival rates of nu_μ+ \barν_μand nu_e + \barν_e and (b) 100 kton sized magnetized iron detectors, which can measure the survival rates of ν_μand \barν_μ. For energies and path-lengths relevant to atmospheric neutrinos, these rates obtain significant matter contributions from P_{μe}, P_{μμ} and P_{ee}, leading to an appre…
By lowering their energy threshold direct dark matter searches can reach the neutrino floor with experimental technology now in development. The 7Be flux can be detected with $\sim 10$ eV nuclear recoil energy threshold and 50 kg-yr exposure. The pep flux can be detected with $\sim 3$ ton-yr exposure, and the first detection of the CNO flux is possible with similar exposure. The pp flux can be detected with threshold of $\sim$ eV and only $\sim$ kg-yr exposure. These can be the first pure neutral current measurements of the low-energy solar neutrino flux. Measuring this flux is important for l…
Neutrino interactions beyond the Standard Model (BSM) are theoretically well motivated and have an important impact on the future precision measurement of neutrino oscillation. In this work, we study the sensitivity of a multi-ton-scale liquid Xenon dark matter detector equipped with an intense radiative neutrino source to various BSM neutrino-electron interactions. We consider the conventional Non-Standard Interactions (NSIs), other more generalized four-fermion interactions including scalar and tensor forms, and light-boson mediated interactions. The work shows that with realistic experiment…
We investigate the effects of possible decay of neutrinos from a neutrino factory in a long baseline experiment. We consider the neutrinos from a factory at CERN and the detector to be the 50 kTon iron calorimeter (ICAL) detector proposed for India-based Neutrino Observatory (INO). We found considerable depletion of muon yield at INO for certain value of decay parameters.
Neutrino-electron scattering can be used to probe neutrino electromagnetic properties at low-threshold underground detectors with good angular and recoil electron energy resolution. We propose to do this using a number of artificial neutrino and anti-neutrino sources such as $^{51}Cr_{24}$ and $^{90}Sr-Y$. The neutrino flux is known to within one percent, in contrast to the reactor case and one can reach lower neutrino energies. For the $^{90}Sr-Y$ source we estimate that the signal expected for a neutrino magnetic moment of $μ_ν=6 \times 10^{-11}μ_{B}$ will be comparable to that expected in t…
We consider threshold effects on neutrino masses and mixings in a recently proposed model for understanding large solar and atmospheric mixing angles using radiative magnification for the case of quasi-degenerate neutrinos. We show that the magnitude of the threshold effects is sufficient to bring concordance between the predictions of this model and latest data from ${\rm KamLAND}$ and ${\rm SNO}$ on observations of neutrino oscillations.
We have identified some important and worthwhile physics opportunitites with a possible neutrino detector located in India. Particular emphasis is placed on the geographical advantage with a stress on the complimentary aspects with respect to other neutrino detectors already in operation.
We study electron-neutrino and electron-antineutrino signals from a supernova with strong magnetic field detected by a 100 kton liquid Ar detector. The change of neutrino flavors by resonant spin-flavor conversions, matter effects, and neutrino self-interactions are taken into account. Different neutrino signals, characterized by neutronization burst event and the total event numbers of electron-neutrinos and electron-antineutrinos, are expected with different neutrino oscillation parameters and neutrino magnetic moment. Observations of supernova neutrino signals by a 100 kton liquid Ar detect…
We discuss how and to what extent one can determine the neutrino mass hierarchy, normal or inverted, and at the same time uncover CP violation in the lepton sector by using two identical detectors with different baselines in neutrino oscillation experiments using low energy superbeam from the J-PARC facility.
The detection of collider neutrinos will provide new insights about neutrino production, propagation, and interactions at TeV energies, the highest human-made energies ever observed. During Run 3 of the LHC, the FASER experiment is expected to detect roughly $10^4$ collider neutrinos using its emulsion-based neutrino detector FASER$ν$. In this study, we show that, even without processing the emulsion data, low-level input provided by the electronic detector components of FASER and FASER$ν$ will be able to establish a $5σ$ discovery of collider neutrinos with as little as $5~\text{fb}^{-1}$ of …
Coherent elastic neutrino- and WIMP-nucleus interaction signatures are expected to be quite similar. This paper discusses how a next generation ton-scale dark matter detector could discover neutrino-nucleus coherent scattering, a precisely-predicted Standard Model process. A high intensity pion- and muon- decay-at-rest neutrino source recently proposed for oscillation physics at underground laboratories would provide the neutrinos for these measurements. In this paper, we calculate raw rates for various target materials commonly used in dark matter detectors and show that discovery of this int…
We report the neutrino mass hierarchy (MH) sensitivity of medium baseline reactor neutrino experiments with multiple detectors. Sensitivity of determining the MH can be significantly improved by adding a near detector and combining both the near and far detectors. The size of the sensitivity improvement is related to accuracy of the individual mass-splitting measurements and requires strict control on the relative energy scale uncertainty of the near and far detectors. We study the impact of both baseline and target mass of the near detector on the combined sensitivity. A figure-of-merit is de…
In this work, the supernova neutrino(SN) charged-current interactions with Gd odd isotopes (A=155 and 157) are studied. We use measured spectra and the quasiparticle-phonon model (MQPM) to calculate the charged current response of odd Gd isotopes to supernova neutrinos. Flux-averaged cross-sections are obtained considering quasi-thermal neutrino spectra.
We consider searches for dark matter annihilation to monoenergetic neutrinos in the core of the Sun. We find that liquid scintillation neutrino detectors have enhanced sensitivity to this class of dark matter models, due to the energy and angular resolution possible for electron neutrinos and antineutrinos that scatter via charged-current interactions. In particular we find that KamLAND, utilizing existing data, could provide better sensitivity to such models than any current direct detection experiment for $m_X \lesssim 15$ GeV. KamLAND's sensitivity is signal-limited, and future liquid scint…
The Kamioka-Korea two detector system is a powerful experimental setup for resolving neutrino parameter degeneracies and probing CP violation in neutrino oscillation. In this paper, we study sensitivities of this same setup to several nonstandard neutrino physics such as quantum decoherence, tiny violation of Lorentz symmetry, and nonstandard interactions of neutrinos with matter. In most cases, the Kamioka-Korea two-detector setup is more sensitive than the one-detector setup, except for the Lorentz symmetry violation with CPT violation, and the nonstandard neutrino interactions with matter. …
We discuss various aspects of a neutrino physics program that can be carried out with the neutrino Beam-Dump eXperiment DRIFT ($ν$BDX-DRIFT) detector using neutrino beams produced in next generation neutrino facilities. $ν$BDX-DRIFT is a directional low-pressure TPC detector suitable for measurements of coherent elastic neutrino-nucleus scattering (CE$ν$NS) using a variety of gaseous target materials which include carbon disulfide, carbon tetrafluoride and tetraethyllead, among others. The neutrino physics program includes standard model (SM) measurements and beyond the standard model (BSM) ph…
Opaque detectors are a recently proposed novel detector concept where an opaque scintillator aligned with wavelength-shifting fibers is used to enable the discrimination of electron neutrinos and antineutrinos with a rather low energy threshold. In this work, we investigate the potential effects of the enhanced detection capabilities of the opaque detectors in accelerator neutrino experiments. Focusing on the energy threshold, energy resolution, detection efficiency and background suppression in the analysis of electron-like events, we determine whether using opaque detectors could lead to imp…
The significant neutrino flux at high rapidity at the LHC motivates dedicated forward detectors to study the properties of neutrinos at TeV energies. We investigate magnetic dipole interactions between the active neutrinos and new sterile states at emulsion and liquid argon experiments that could be located in a future Forward Physics Facility (FPF) downstream of the ATLAS interaction point. The up-scattering of neutrinos off electrons produces an electron recoil signature that can probe new regions of parameter space at the High Luminosity LHC (HL-LHC), particularly for liquid argon detectors…
Neutrino-induced recoil events may constitute a background to direct dark matter searches, particularly for those detectors that strive to reach the ton-scale and beyond. This paper discusses the expected neutrino-induced background spectrum due to several of the most important sources, including solar, atmospheric, and diffuse supernova neutrinos. The largest rate arises from $^8$B produced solar neutrinos, providing upwards of $\sim 10^3$ events per ton-year over all recoil energies for the heaviest nuclear targets. However the majority of these $^8$B events are expected to be below the reco…
In the winter season of 2000, the AMANDA (Antarctic Muon And Neutrino Detector Array) detector was completed to its final state. We report on major physics results obtained from the AMANDA-B10 detector, as well as initial results of the full AMANDA-II detector.
The SuperKamiokande group assert that they have found an oscillatory signature in atmospheric neutrinos through the analysis of \textit{Fully Contained Events} and \textit{Partially Contained Events}. We have performed an $L/E$ (length/energy) analysis of \textit{Upward Through-Going Muon Events} and \textit{Stopping Muon Events} in a numerical computer simulations both with and without neutrino oscillations but were unable to find an oscillatory signature. We give likely explanations for the absence of the oscillatory signature in our simulations and its apparent presence in the SuperKamiokan…
The geometric effects of the beam in near detectors at a neutrino factory are discussed. The refined systematics treatment, including cross section errors, flux errors and background uncertainties, is compared with the IDS-NF one. Different near detector setups are included. We also probe their effects both at the measurements of standard neutrino oscillation parameters and constraints of the non-standard neutrino interaction.
Binary neutron star (BNS) mergers can be sources of ultrahigh-energy (UHE) cosmic rays and potential emitters of UHE neutrinos. The upcoming and current radio neutrino detectors like the Giant Radio Array for Neutrino Detection (GRAND), IceCube-Gen2 Radio, and the Radio Neutrino Observatory in Greenland (RNO-G) are projected to reach the required sensitivities to search for these neutrinos. In particular, in conjunction with the next-generation of gravitational wave (GW) detectors like Cosmic Explorer (CE) and Einstein Telescope (ET), GW-triggered stacking searches can be performed with the UH…
The sensitivity to New Physics of a low threshold scintillating argon bubble chamber measuring coherent elastic neutrino-nucleus scattering in reactors is reported. Namely, light scalar mediators, sterile neutrino oscillations, unitarity violation, and non-standard interactions are studied. The results indicate that this detector could be able to set stronger constraints than current limits set by the recent COHERENT measurements. Considering the best scenario, a 100 kg detector located 30 m from a 2000 MW$_{th}$ reactor, a sterile neutrino search would cover most of the space parameter allowe…
We review detector technologies which are currently considered for ultimate nucleon decay searches, new generation astrophysical neutrinos studies, and for future long-baseline neutrino experiments at new high-intensity neutrino beam facilities. We focus our discussion on Phase-II experiments with a timescale of $10\simeq 20$ years. We point out that there are very few detector technologies which are general purpose and versatile enough in order to potentially address non-accelerator based physics and a large variety of future neutrino beam types ranging from superbeams, betabeams and neutrino…
In this letter we point out the possibility to study new physics in the neutrino sector using dark matter detectors based on liquid xenon. These are characterized by very good spatial resolution and extremely low thresholds for electron recoil energies. When combined with a radioactive $ν_e$ source, both features in combination allow for a very competitive sensitivity to neutrino magnetic moments and sterile neutrino oscillations. We find that, for realistic values of detector size and source strength, the bound on the neutrino magnetic moment can be improved by an order of magnitude with resp…
We consider the threshold effect on the renormalization group (RG) evolution of the neutrino masses and mixing angles in TeV scale seesaw models. We obtain the analytic expressions using the factorization method in presence of threshold effects. We also perform numerical study of RG effects in two specific low scale seesaw models following the bottom-up approach and ascertain the role of seesaw thresholds in altering the values of masses and mixing angles during RG evolution.
The existence of the coherent neutrino-nucleus scattering reaction requires to evaluate, for any detector devoted to WIMP searches, the irreducible background due to conventional neutrino sources and at same time, it gives a unique chance to reveal supernova neutrinos. We report here a detailed study concerning a new directional detector, based on the nuclear emulsion technology. A Likelihood Ratio test shows that, in the first years of operations and with a detector mass of several tens of tons, the observation of the supernova signal can be achieved. The determination of the distance of the …
We explore the neutrino portal dark matter (DM) at its minimum of field content having two dark sector particles coupled to a right-handed neutrino. Assuming the feeble nature of their interactions with the standard model (SM) particles, we analyze the freeze-in production of the observed DM relic density characterized by three different categories depending on the major production mechanisms. The portal provides interesting signatures at the neutrino detectors like KamLAND, Super-Kamiokande and IceCube, from a very late decay of the scalar DM to the fermion DM and the SM neutrino. Such neutri…
The experimental searches for diffuse supernova neutrino background and proton decay in next-generation large liquid-scintillator (LS) detectors are competitive with and complementary to those in the water-Cherenkov detectors. In this paper, we carry out a systematic study of the dominant background induced by atmospheric neutrinos via their neutral-current (NC) interactions with the $^{12}{\rm C}$ nuclei in the LS detectors. The atmospheric neutrino fluxes at the location of Jiangmen Underground Neutrino Observatory (JUNO) are used, as the JUNO detector is obviously a suitable representative …
In recent years great progress toward the understanding of the mixing in the leptonic sector has been made. Nonetheless, this field of research is just at the beginning. Further advance by accelerator based neutrino oscillation experiments requires new beams and detectors to reach the wanted physics goals. In this paper we review the next possible steps that can be done for neutrino oscillation experiments with accelerators
Sterile neutrino conversion in meter scale baselines can be sensitively probed using monoenergetic, sub-MeV, flavor pure e-neutrinos from an artificial MCi source and the unique technology of LENS designed to oberve the low energy solar neutrino spectrum via tagged CC e-neutrino capture in 115-In. Active-sterile oscillations can be directly observed in the granular LENS detector itself to critically test and extend resuls of short baseline accelerator and reactor experiments.
The time dependent neutrino oscillation signals due to the passage of a shock wave through the supernovae are analyzed for the case of three active neutrinos and also for the case that there are two additional sterile neutrinos. It is shown that, even without flavour identification and energy measurement, detailed information about the masses and mixing angles of the neutrinos may be obtained with a detector with excellent time resolution such as IceCube. Such a signal would also give important information about the nature of the shock wave within the supernovae.
Orbiting detectors will be able to observe showers initiated by neutrinos penetrating the Earth and interacting close to their exit point. There is a correlation between the impact parameter of the incident neutrino and its energy. We study the development of upward going, neutrino induced showers in the atmosphere.
Neutrinos produced in the Sun by electron capture reactions on $^{13}{\rm N}$, $^{15}{\rm O}$ and $^{17}{\rm F}$, to which we refer as ecCNO neutrinos, are not usually considered in solar neutrino analysis since the expected fluxes are extremely low. The experimental determination of this sub-dominant component of the solar neutrino flux is very difficult but could be rewarding since it provides a determination of the metallic content of the solar core and, moreover, probes the solar neutrino survival probability in the transition region at $E_ν\sim 2.5\,{\rm MeV}$. In this letter, we suggest …
The presence of two monochromatic lines of approximately equal intensity: $^{7}$Be- and pep-neutrinos in the sensitivity plot of lithium detector makes the pattern of the seasonal variations of the effect from solar neutrinos very characteristic in case if the long-wave vacuum oscillations are realized. This can give the very high accuracy in the measurement of the parameters of neutrino oscillations especially if combined with the results obtained by the detector sensitive mainly to $^{7}$Be-line like BOREXINO or KamLAND.
Here we estimate the magnitude of the signals expected for realistic cosmic neutrino backgrounds in detectors attempting to measure the mechanical forces exerted on macroscopic targets by the elastic scattering of relic neutrinos. We study effects proportional to the weak coupling constant $G_F$ and to $G_F^2$ for Dirac and Majorana neutrinos, either relativistic or non-relativistic, both gravitationally bound or not.
Neutrinos are the least detectable Standard Model particle. By making use of this fact, we consider dark matter annihilations and decays in the galactic halo and show how present and future neutrino detectors could be used to set general limits on the dark matter annihilation cross section and on the dark matter lifetime.
The apparent symmetry between energy and momentum found in all covariant descriptions of neutrino oscillations is destroyed in the neutrino detector, a quantum mechanical system described by a density matrix diagonal in energy but not in momentum. The off diagonal matrix elements between states of different momenta and the same energy produce the coherence and interference between mass eigenstates having the same energy and different momenta that produce oscillations.
