Neutrino Interaction Cross Sections Research Articles

First Measurement of ν_{e} and ν_{μ} Interaction Cross Sections at the LHC with FASER's Emulsion Detector.

The first results of the study of high-energy electron neutrino (ν_{e}) and muon neutrino (ν_{μ}) charged-current interactions in the FASERν emulsion-tungsten detector of the FASER experiment at the LHC are presented. A 128.8kg subset of the FASERν volume was analyzed after exposure to 9.5 fb^{-1} of sqrt[s]=13.6 TeV pp data. Four (eight) ν_{e} (ν_{μ}) interaction candidate events are observed with a statistical significance of 5.2σ (5.7σ). This is the first direct observation of ν_{e} interactions at a particle collider and includes the highest-energy ν_{e} and ν_{μ} ever detected from an artificial source. The interaction cross section per nucleon σ/E_{ν} is measured over an energy range of 560-1740GeV (520-1760GeV) for ν_{e} (ν_{μ}) to be (1.2_{-0.7}^{+0.8})×10^{-38} cm^{2} GeV^{-1} [(0.5±0.2)×10^{-38} cm^{2} GeV^{-1}], consistent with standard model predictions. These are the first measurements of neutrino interaction cross sections in those energy ranges.

Neutrino Experiments at the LHC

The LHC neutrino experiments, FASER and SND@LHC were approved by the CERN Research Board in 2019 and 2021, respectively, to operate during LHC Run 3. Both experiments began taking physics data in July 2022 and have since recorded approximately 70 fb-1 of data from proton-proton collisions with a center-of-mass energy of 13.6 TeV. These experiments achieved the first direct observation of neutrino interactions at the LHC, using the active electronic components of their detector. Additionally, FASERν, using 2% of its data sample, detected the highest-energy νe and νµ interactions ever observed from an artificial source and made the first measurements of neutrino interaction cross-sections over energy ranges of 560–1740 GeV for νe and 520–1760 GeV for νµ. Additionally, both experiments are actively searching for physics beyond the Standard Model, with FASER already publishing initial results on Dark Photons and Axion-like Particles. In this report, we will discuss the status of the experiments, including the detector concept, performance, and the first physics results from Run 3 data.

High-Energy to Ultrahigh-Energy Neutrino Interactions

The cross sections for neutrino interactions with nucleons have been measured directly in accelerator experiments and through the zenith-angle and energy dependence of neutrino events at the IceCube Neutrino Observatory. Fluxes of high-energy neutrinos are produced at the Large Hadron Collider and by cosmic rays in the atmosphere. High-energy neutrinos also come from astrophysical and cosmic sources. The theory of neutrino interactions is reviewed. Current cross-section measurements and prospects for the future are discussed. The focus here is on neutrino interactions for energies larger than 1 TeV.

Characterization of a kg-scale archaeological lead-based PbWO[formula omitted] cryogenic detector for the RES-NOVA experiment

Core-collapse Supernovae (SNe) are one of the most energetic events in the Universe, during which almost all the star’s binding energy is released in the form of neutrinos. These particles are direct probes of the processes occurring in the stellar core and provide unique insights into the gravitational collapse. RES-NOVA will revolutionize how we detect neutrinos from astrophysical sources, by deploying the first ton-scale array of cryogenic detectors made from archaeological lead. Pb offers the highest neutrino interaction cross-section via coherent elastic neutrino-nucleus scattering (CEνNS). Such process will enable RES-NOVA to be equally sensitive to all neutrino flavours. For the first time, we propose the use archaeological Pb as sensitive target material in order to achieve an ultra-low background level in the region of interest (O(1 keV)). All these features make possible the deployment of the first cm-scale neutrino telescope for the investigation of astrophysical sources. In this contribution, we will characterize the radiopurity level and the performance of a small-scale proof-of-principle detector of RES-NOVA, consisting in a PbWO4 crystal made from archaeological-Pb operated as cryogenic detector.

Neutrino interactions and detections: Review and future potential

Both experimentally and theoretically, neutrino physics thrives to be the most active and volatile area of research. The Beyond Standard Model physics of electroweak interactions became evident with the plethora of sophisticated neutrino detectors across the globe. Neutrino interaction with detector constituents plays a critical role in neutrino physics which concerns the cross section measurements. Neutrino cross sections are an essential constituent in neutrino experiments to study neutrino properties and their sources. With the advent of new precision experiments and intense neutrino sources constructed to investigate neutrino oscillations, the seemingly small neutrino interaction cross section demands precision measurements for a better understanding. We have presented a survey on neutrino interactions and cross sections in a concise format. We have also discussed the detection principle of neutrino detectors around the globe till date. Efforts have been made to discuss the neutrino interactions and cross sections based on the target element in the detector rather than interactions across the energy scale so as to understand the working principle and interaction mechanism in prospective neutrino detectors.

Study of final-state interactions of protons in neutrino-nucleus scattering with INCL and NuWro cascade models

The modeling of neutrino-nucleus interactions constitutes a challenging source of systematic uncertainty for the extraction of precise values of neutrino oscillation parameters in long-baseline accelerator neutrino experiments. To improve such modeling and minimize the corresponding uncertainties, a new generation of detectors is being developed, which aim to measure the complete final state of particles resulting from neutrino interactions. In order to fully benefit from the improved detector capabilities, precise simulations of the nuclear effects on the final-state nucleons are needed. This article presents the study of the in-medium propagation of knocked-out protons, i.e., final-state interactions (FSI), comparing the NuWro and INCL cascade models. The INCL model is used here for the first time to predict exclusive final states in measured neutrino interaction cross sections. This study of INCL in the framework of neutrino interactions features various novelties, including the production of nuclear clusters (e.g., deuterons, $\ensuremath{\alpha}$ particles) in the final state. The paper includes a complete characterization of the final state after FSI, comparisons to available measurements of single transverse variables, and an assessment of the observability of nuclear clusters.

DsTau: study of tau neutrino production with nuclear emulsion in the CERN-SPS

Tau neutrino is one of the least known particle of Standard Model; there are only few measurements with a limited statistics. The DONUT experiment first reported the tau neutrino interaction cross-section but their measurement suffers from large systematic error of more than 50\%50% which is mainly due to uncertainty in the tau neutrino flux prediction. The tau neutrino cross section is an essential ingredient in neutrino experiments and its precise measurement would enable a search for new physics effects such as testing the Lepton Universality in neutrino interactions. The main goal of the DsTau experiment is to measure an inclusive differential cross-section of a D_sDs production with a consecutive decay to tau lepton in p-A interactions at the CERN-SPS. The measurement of DsTau will reduce the systematic uncertainty in tau neutrino interaction cross-section to 10\%10% level. The results from the pilot run and the prospect for physics runs in 2021-2022 will be discussed.

Evaluation of event reconstruction with small-scale water Cherenkov detectors

The Hyper-Kamiokande experiment is planned to start in 2027 aiming for precise measurement of neutrino oscillation using J-PARC neutrino beam including the search for CP violation in the lepton sector. The Hyper-Kamiokande detector is a 260 kiloton water Cherenkov detector. In order to achieve the precision measurement, systematic uncertainties should be suppressed. For this purpose, a new 1 kiloton scale Intermediate Water Cherenkov Detector (IWCD) is proposed to measure the neutrino flux and interaction cross section near the generation point of the neutrino beam before oscillation. Water Cherenkov Test Experiment (WCTE) is a 50 ton scale water Cherenkov detector and currently under preparation to validate the performance of IWCD. WCTE will use new photosensor called multi-PMT and study the response of small water Cherenkov detectors to electron, muon, and hadron beams at CERN. The performance of event reconstruction with the IWCD and WCTE detectors is evaluated using simulation.

Improving Hyper-Kamiokande sensitivity to CP violation with high precision near detector electron neutrino cross-section measurements

The next generation long-baseline neutrino oscillation experiment, Hyper-Kamiokande, will consist of a 260 kt underground water Cherenkov detector, placed 295 km from the neutrino source at J-PARC. This is generated by a 1.3 MW proton beam striking a target. In addition, a suite of near detectors, both on and off-axis will be used. With this, Hyper-Kamiokande aims to perform precision measurements of the parameters governing neutrino oscillations, the observation of CP violation being one of the main aims of the experiment. To achieve these goals, Hyper-Kamiokande will require smaller systematic uncertainties than in any previous long-baseline experiment.Many of these systematic uncertainties are related to neutrino-nucleus interactions, and can be constrained by a detector placed close to the beam production point. For this, the Hyper-Kamiokande long-baseline programme includes an Intermediate Water Cherenkov Detector, the IWCD. This is a 500 tonne water Cherenkov detector located 1 km from the beam production point. This detector is able to move within a vertical shaft and span a range of off-axis angles relative to the beam, from 1 to 4 degrees. The combination of large target mass, precise water Cherenkov reconstruction and off-axis angle flux dependence allows for high purity and high statistics electron neutrino and electron antineutrino samples. This paper describes how this detector can be used to constrain the major systematic uncertainty affecting the measurement of CP violation at Hyper-Kamiokande: the electron neutrino and antineutrino interaction cross section.

T2K latest results on neutrino-nucleus cross sections

Neutrino interaction cross section measurements are of high importance, in improving understanding for both oscillation measurements and nuclear modelling. The T2K experiment features a near detector complex with multiple detectors, providing multiple different nuclear targets at differing mean neutrino energies due to the off-axis configurations used. Along with constraining the flux for oscillation measurements, these near detectors provide the opportunity for a large programme of neutrino cross section measurements. Some recent such measurements are described in this proceeding.

Study of tau neutrino production with nuclear emulsion at CERN-SPS

The tau neutrino interaction cross-section was directly measured in the DONuT experiment but it suffers from a large systematic (∼50%) and statistical (∼30%) errors. The main source of the systematic error was due to poor knowledge of the tau neutrino flux. The DsTau experiment at CERN-SPS has been proposed to measure an inclusive differential cross-section of the Ds production with a consecutive decay to tau lepton in p-A interactions, which is a main source of tau neutrinos in neutrino beams at accelerators. The search for Ds → τ → X decay is challenging due to milimetric range of Ds and τ decay lengths and a small angle between them of the order of few mrad. Nevertheless a precise measurement is possible with the use of nuclear emulsion providing a sub-micron spatial resolution. The experiment is aiming to collect 2.3 × 108 proton interactions in the tungsten target, and to detect ∼ 1000 Ds → τ → X decays. DsTau successfully performed a pilot run in 2018 collecting ∼10% of the full data and was approved as NA65 in 2019. The results from the pilot run are presented in this paper and the prospect for physics runs in 2021–2022 are given.

Measurement of the high-energy all-flavor neutrino-nucleon cross section with IceCube

The flux of high-energy neutrinos passing through the Earth is attenuated due to their interactions with matter. The interaction rate is modulated by the neutrino interaction cross section and affects the flux arriving at the IceCube Neutrino Observatory, a cubic-kilometer neutrino detector embedded in the Antarctic ice sheet. We present a measurement of the neutrino cross section between 60 TeV and 10 PeV using the high-energy starting events (HESE) sample from IceCube with 7.5 years of data. The result is binned in neutrino energy and obtained using both Bayesian and frequentist statistics. We find it compatible with predictions from the Standard Model. Flavor information is explicitly included through updated morphology classifiers, proxies for the the three neutrino flavors. This is the first such measurement to use the three morphologies as observables and the first to account for neutrinos from tau decay.

An improved trigger for Askaryan radio detectors

High-energy neutrinos with energies above a few 1016 eV can be measured efficiently with in-ice radio detectors which complement optical detectors such as IceCube at higher energies. Several pilot arrays explore the radio technology successfully in Antarctica. Because of the low flux and interaction cross-section of neutrinos it is vital to increase the sensitivity of the radio detector as much as possible. In this manuscript, different approaches to trigger on high-energy neutrinos are systematically studied and optimized. We find that the sensitivity can be improved substantially (by more than 50% between 1017 eV and 1018 eV) by simply restricting the bandwidth in the trigger to frequencies between 80 MHz and 200 MHz instead of the currently used 80 MHz to ∼ 1 GHz bandwidth. We also compare different trigger schemes that are currently being used (a simple amplitude threshold, a high/low threshold trigger and a power-integration trigger) and find that the scheme that performs best depends on the dispersion of the detector. These findings inform the detector design of future Askaryan detectors and can be used to increase the sensitivity to high-energy neutrinos significantly without any additional costs. The findings also apply to the phased array trigger concept.

Adjusting neutrino interaction models and evaluating uncertainties using NOvA near detector data

The two-detector design of the NOvA neutrino oscillation experiment, in which two functionally identical detectors are exposed to an intense neutrino beam, aids in canceling leading order effects of cross-section uncertainties. However, limited knowledge of neutrino interaction cross sections still gives rise to some of the largest systematic uncertainties in current oscillation measurements. We show contemporary models of neutrino interactions to be discrepant with data from NOvA, consistent with discrepancies seen in other experiments. Adjustments to neutrino interaction models in GENIE are presented, creating an effective model that improves agreement with our data. We also describe systematic uncertainties on these models, including uncertainties on multi-nucleon interactions from a newly developed procedure using NOvA near detector data.

Searching for Sub-GeV dark matter in the galactic centre using Hyper-Kamiokande

Indirect detection of dark matter via its annihilation products is a key technique in the search for dark matter in the form of weakly interacting massive particles (WIMPs). Strong constraints exist on the annihilation of WIMPs to highly visible Standard Model final states such as photons or charged particles. In the case of s-wave annihilation, this typically eliminates thermal relic cross sections for dark matter of mass below \U0001d4aa(10) GeV . However, such limits typically neglect the possibility that dark matter may annihilate to assumed invisible or hard-to-detect final states, such as neutrinos. This is a difficult paradigm to probe due to the weak neutrino interaction cross section. Considering dark matter annihilation in the Galactic halo, we study the prospects for indirect detection using the Hyper-Kamiokande (HyperK) neutrino experiment, for dark matter of mass below 1 GeV . We undertake a dedicated simulation of the HyperK detector, which we benchmark against results from the similar Super-Kamiokande experiment and HyperK physics projections. We provide projections for the annihilation cross-sections that can be probed by HyperK for annihilation to muon or neutrino final states, and discuss uncertainties associated with the dark matter halo profile. For neutrino final states, we find that HyperK is sensitive to thermal annihilation cross-sections for dark matter with mass around 20 MeV, assuming an NFW halo profile. We also discuss the effects of neutron tagging, and prospects for improving the reach at low mass.

Study of tau neutrino production in proton-nucleus interactions

Tau neutrino properties are not so well known in comparison to those of muon or electron neutrinos. The tau neutrino interaction cross-section was directly measured by the DONUT experiment in 2008 on a basis of 9 registered tau neutrinos, and with a large systematical error of 50% due to a poor knowledge of the tau neutrino flux in this beam dump experiment. However, more accurate measurement of the cross section is needed for future neutrino experiments. It would also allow testing the Lepton Universality (LU) of Standard Model in neutrino interactions. Recently several results for B-meson decays (LHCb, Babar) demonstrated hints of possible LU violation. The tau neutrinos are produced in the Ds meson decays to tau, Ds → τ vT, and the cascade decay of the tau τ → vT X. DsTau experiment has been proposed to study the tau neutrino production at CERN SPS. It will measure the Ds production differential cross-section in the proton-tungsten interactions. This will allow reducing of the uncertainty due to the tau neutrino flux in the DONUT result from 50% to 10%. The peculiar Ds cascade decay topology ("double kink") in a few mm range will be detected by nuclear emulsion tracker thanks to its excellent spatial resolution (∼50nm).In 2016 and 2017, we made test beam exposures of nuclear emulsion modules at CERN SPS 400GeV/c proton beam followed by the pilot run in August 2018. A physics run in 2021 is scheduled. The status and prospects of the DsTau project as well as a review of the modern nuclear emulsion technique and the methods of its data analysis are presented.

English

English

Measurement of the multi-TeV neutrino interaction cross-section with IceCube using Earth absorption.

Neutrinos interact only very weakly, so they are extremely penetrating. The theoretical neutrino-nucleon interaction cross-section, however, increases with increasing neutrino energy, and neutrinos with energies above 40 teraelectronvolts (TeV) are expected to be absorbed as they pass through the Earth. Experimentally, the cross-section has been determined only at the relatively low energies (below 0.4 TeV) that are available at neutrino beams from accelerators. Here we report a measurement of neutrino absorption by the Earth using a sample of 10,784 energetic upward-going neutrino-induced muons. The flux of high-energy neutrinos transiting long paths through the Earth is attenuated compared to a reference sample that follows shorter trajectories. Using a fit to the two-dimensional distribution of muon energy and zenith angle, we determine the neutrino-nucleon interaction cross-section for neutrino energies 6.3-980 TeV, more than an order of magnitude higher than previous measurements. The measured cross-section is about 1.3 times the prediction of the standard model, consistent with the expectations for charged- and neutral-current interactions. We do not observe a large increase in the cross-section with neutrino energy, in contrast with the predictions of some theoretical models, including those invoking more compact spatial dimensions or the production of leptoquarks. This cross-section measurement can be used to set limits on the existence of some hypothesized beyond-standard-model particles, including leptoquarks.

New experiment WAGASCI to measure cross sections of neutrino interactions in water and hydrocarbon using J-PARC beam

The main objective of the long base T2K,Tokai-to-Kamioka, Japan, experiment is the investigation of neutrino oscillations with a high-intensity beam of muon neutrinos and antineutrinos. Neutrino interaction measurements in the near detector complex (ND280) of the Т2К experiment are used for adjustment of the parameters defining event simulation in the far detector (Super-Kamiokande), which is the key idea of the experiment; this allows one to considerably increase the oscillation analysis accuracy. The difference in the target material of the far (water) and near (scintillator, hydrocarbon) detectors results in a substantial systematic error in oscillation analysis. Systematic error can be reduced by direct measurements, a new water grid and scintillator detector WAGASCI was proposed for this purpose. The detector will operate at the J-PARC neutrino beam and measure the ratio of charged-current neutrino cross sections between water and hydrocarbon with a few percent precision. Further physical programs may include precise measurements of various charged channels of neutrino interaction. This paper presents the detector concept and the current plan for its installation.

Inelastic scattering of neutrinos on nuclei

The cross section of inelastic neutrino interaction with 56Fe and 208Pb nuclei is calculated. Investigation of these processes caused by neutral currents is essential for considering phenomena that occur during Supernova explosions and designing astrophysical neutrino detectors. The inelastic neutrino scattering cross section is calculated using the model independent approach, which is based on experimental data on nuclear structure. The values of the matrix elements of the considered reaction are determined from the characteristics of electromagnetic dipole М1 transitions in nuclei, obtained by means of nuclear resonance fluorescence.