We report the best limit on coherent elastic scattering of electron antineutrinos emitted from a nuclear reactor off germanium nuclei. The measurement was performed with the CONUS detectors positioned at 17.1m from the 3.9GWth reactor core of the nuclear power plant in Brokdorf, Germany. The antineutrino energies of less than 10 MeV assure interactions in the fully coherent regime. The analyzed dataset includes 248.7 kgd with the reactor turned on and background data of 58.8 kgd with the reactor off. With a quenching parameter of k = 0.18 for germanium, we determined an upper limit on the number of neutrino events of 85 in the region of interest at 90% confidence level. This new CONUS dataset disfavors quenching parameters above k = 0.27, under the assumption of standard-model-like coherent scattering of the reactor antineutrinos.
Sub-keV energy calibration of CONUS+ via 71Ge M-shell neutron activation
Max-Planck-Institut für Kernphysik（马克斯·普朗克核物理研究所）；Karlsruher Institut für Technologie (KIT)（卡尔斯鲁厄理工学院）；Marietta-Blau-Institut für Teilchenphysik der ÖAW（奥地利科学院玛丽埃塔·布劳粒子物理研究所）；Mirion Technologies (Canberra) GmbH（米尔恩技术（堪培拉）有限公司）
The detection of coherent elastic neutrino-nucleus scattering (CE$ν$NS) opens new possibilities for neutrino physics within and beyond the Standard Model. Following the initial discovery in 2017, several experimental attempts have emerged allowing this reaction channel to be studied with the full repertoire of modern detection technologies. As one of several reactor experiments, CONUS aims for an observation with antineutrinos emitted from the powerful $3.9$ GW$_{th}$ reactor of the nuclear power plant in Brokdorf (Germany). In particular, the application of ultra-low threshold, high-purity ge…
The measurements of coherent elastic neutrino-nucleus scattering (CE$ν$NS) experiments have opened up the possibility to constrain neutrino physics beyond the standard model of elementary particle physics. Furthermore, by considering neutrino-electron scattering in the keV-energy region, it is possible to set additional limits on new physics processes. Here, we present constraints that are derived from CONUS germanium data on beyond the standard model (BSM) processes like tensor and vector non-standard interactions (NSIs) in the neutrino-quark sector, as well as light vector and scalar mediato…
We consider the production of a new MeV-scale fermion in coherent elastic neutrino-nucleus scattering. The effect on the measurable nucleon recoil spectrum is calculated. Assuming that the new fermion couples to neutrinos and quarks via a singlet scalar, we set limits on its mass and coupling using COHERENT data and also determine the sensitivity of the CONUS experiment. We investigate the possible connection of the new fermion to neutrino mass generation. The possibility of the new fermion being the dark matter particle is also studied.
New constraints on physics within and beyond the standard model from the latest CONUS datasets
Max-Planck-Institut für Kernphysik（马克斯·普朗克核物理研究所）；University of Strasbourg（斯特拉斯堡大学）；CNRS, IPHC UMR 7178（法国国家科学研究中心，高能物理研究所）；PreussenElektra GmbH, Kernkraftwerk Brokdorf（普鲁士电力公司布罗克多夫核电站）；Marietta Blau Institute for Particle Physics of the Austrian Academy of Sciences (MBI)（奥地利科学院玛丽亚·布劳粒子物理研究所）；Mirion Technologies (Canberra) GmbH（米里恩技术（堪培拉）有限公司）
Rates of coherent neutrino-nucleus elastic scattering at a high-intensity stopped-pion neutrino source in various detector materials (relevant for novel low-threshold detectors) are calculated. Sensitivity of a coherent neutrino-nucleus elastic scattering experiment to new physics is also explored.
We present recent measurements of neutrino charged current quasi-elastic (CC QE) scattering, nu_mu + p -> mu- + n. Measurements of CC QE on carbon near 1 GeV by MiniBooNE and SciBooNE, as well as measurements on iron at 3 GeV by MINOS, disagree with current interaction models, while measurements at higher energies on carbon by NOMAD show excellent agreement with those same models.
The nuGeN experiment is aimed to investigate neutrino properties using antineutrinos from the reactor of the Kalinin Nuclear Power Plant. The experimental setup is located at about 11 meters from the center of the 3.1 GWth reactor core. Scattering of the antineutrinos from the reactor is detected with low energy threshold high purity germanium detector. Passive and active shieldings are used to suppress all kinds of backgrounds coming from surrounding materials and cosmic radiation. The description of the experimental setup together with the first results is presented. The data taken in regime…
In the presence of neutrino Non-Standard Interactions (NSI) with matter, the derivation of neutrino parameters from oscillation data must be reconsidered. In particular, along with the standard solution to neutrino oscillation, another solution known as "LMA--Dark" is compatible with global oscillation data and requires both $θ_{12}>π/4$ and a certain flavor pattern of NSI with an effective coupling comparable to $G_F$. Contrary to conventional expectations, there is a class of models based on a new $U(1)_X$ gauge symmetry with a gauge boson of mass of few MeV to few 10 MeV that can viably giv…
Coherent elastic neutrino scattering on the 40Ar nucleus is computed with coupled-cluster theory based on nuclear Hamiltonians inspired by effective field theories of quantum chromodynamics. Our approach is validated by calculating the charge form factor and comparing it to data from electron scattering. We make predictions for the weak form factor, the neutron radius, and the neutron skin, and estimate systematic uncertainties. The neutron-skin thickness of 40Ar40 is consistent with results from density functional theory. Precision measurements from coherent elastic neutrino-nucleus scatterin…
The presence of new neutrino-quark interactions can enhance, deplete or distort the coherent elastic neutrino-nucleus scattering (CEvNS) event rate. The new interactions may involve CP violating phases that can potentially affect these features. Assuming light vector mediators, we study the effects of CP violation on the CEvNS process in the COHERENT sodium-iodine, liquid argon and germanium detectors. We identify a region in parameter space for which the event rate always involves a dip and another one for which this is never the case. We show that the presence of a dip in the event rate spec…
Interpretation of current and future neutrino oscillation and electron scattering experiments requires knowledge of lepton-nucleon and lepton-nucleus interactions at the percent level. We study the exchange of photons between charged particles and the nuclear medium for (anti)neutrino-, electron-, and muon-induced reactions inside a large nucleus. While quantum electrodynamics (QED)-medium contributions are formally suppressed by two powers of the electromagnetic coupling constant $α$ when compared to the leading-order cross sections, low-energy modes and the nuclear size enhance the effect by…
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…
The COHERENT collaboration measured coherent elastic neutrino-nucleus scattering (CEvNS) for the first time at the Spallation Neutron Source at Oak Ridge National Laboratory, using a CsI[Na] detector. Here we discuss the nature of the CEvNS process, physics motivations, and experimental considerations for measuring CEvNS. We describe the CsI[Na] measurement, along with status and future of COHERENT.
The 96.4 day exposure of a 3 kg ultra-low noise germanium detector to the high flux of antineutrinos from a power nuclear reactor is described. A very strong preference ($p<1.2\times10^{-3}$) for the presence of a coherent elastic neutrino-nucleus scattering (CE$ν$NS) component in the data is found, when compared to a background-only model. No such effect is visible in 25 days of operation during reactor outages. The best-fit CE$ν$NS signal is in good agreement with expectations based on a recent characterization of germanium response to sub-keV nuclear recoils. Deviations of order 60\% from t…
Neutrino-nucleus elastic scattering provides a unique laboratory to study the quantum mechanical coherency effects in electroweak interactions, towards which several experimental programs are being actively pursued. We report results of our quantitative studies on the transitions towards decoherency. A parameter ($α$) is identified to describe the degree of coherency, and its variations with incoming neutrino energy, detector threshold and target nucleus are studied. The ranges of $α$ which can be probed with realistic neutrino experiments are derived, indicating complementarity between projec…
Coherent elastic neutrino-nucleus scattering (CE$ν$NS), a process recently measured for the first time at ORNL's Spallation Neutron Source, is directly sensitive to the weak form factor of the nucleus. The European Spallation Source (ESS), presently under construction, will generate the most intense pulsed neutrino flux suitable for the detection of CE$ν$NS. In this paper we quantify its potential to determine the root mean square radius of the point-neutron distribution, for a variety of target nuclei and a suite of detectors. To put our results in context we also derive, for the first time, …
Neutrino-nucleus elastic scattering ($ν{\rm A}_{el}$) provides a unique laboratory to study the quantum-mechanical (QM) coherency effects in electroweak interactions. The deviations of the cross-sections from those of completely coherent systems can be quantitatively characterized through a coherency parameter $α( q^2 )$. The relations between $α$ and the underlying nuclear physics in terms of nuclear form factors are derived. The dependence of cross-section on $α( q^2 )$ for the various neutrino sources is presented. The $α( q^2 )$-values are evaluated from the measured data of the COHERENT C…
In this paper, we revisit the expressions for the (double) differential event rates for elastic WIMP-nucleus scattering and discuss some unusual thoughts on (the incompleteness of) the uses of these expressions in (directional) direct Dark Matter detection physics. Several not-frequently mentioned (but important) issues will be argued and demonstrated in detail.
Potential applications of neutrino detection to nuclear security have been discussed since the 1970s. Recent years have seen great progress in detector technologies based on inverse beta decay, with the demonstration of ton-scale surface-level detectors capable of high quality neutrino spectrum measurements. At the same time coherent elastic neutrino nucleus scattering has been experimentally confirmed in 2017 with neutrinos from stopped pion decay and there is a number of experiments aimed at seeing this reaction with reactor neutrinos. The large cross section and threshold-less nature of thi…
We examine the current constraints and future sensitivity of Coherent Elastic Neutrino-Nucleus Scattering (CE$ν$NS) experiments to mixing scenarios involving a $Z^\prime$ which interacts via portals with the Standard Model. We contrast the results against those from fixed target, atomic parity violation, and solar neutrino experiments. We demonstrate a significant dependence of the experimental reach on the $Z'$ coupling non-universality and the complementarity of CE$ν$NS to existing searches.
A new measurement of the quenching factor for low-energy nuclear recoils in CsI[Na] is presented. Past measurements are revisited, identifying and correcting several systematic effects. The resulting global data are well-described by a physics-based model for the generation of scintillation by ions in this material, in agreement with phenomenological considerations. The uncertainty in the new model is reduced by a factor of four with respect to an energy-independent quenching factor initially adopted as a compromise by the COHERENT collaboration. A significantly improved agreement with Standar…
The European Spallation Source (ESS), presently well on its way to completion, will soon provide the most intense neutron beams for multi-disciplinary science. Fortuitously, it will also generate the largest pulsed neutrino flux suitable for the detection of Coherent Elastic Neutrino-Nucleus Scattering (CE$ν$NS), a process recently measured for the first time at ORNL's Spallation Neutron Source. We describe innovative detector technologies maximally able to profit from the order-of-magnitude increase in neutrino flux provided by the ESS, along with their sensitivity to a rich particle physics …
We study the sensitivity of detectors with directional sensitivity to coherent elastic neutrino-nucleus scattering (CE$ν$NS), and how these detectors complement measurements of the nuclear recoil energy. We consider stopped pion and reactor neutrino sources, and use gaseous helium and fluorine as examples of detector material. We generate Standard Model predictions, and compare to scenarios that include new, light vector or scalar mediators. We show that directional detectors can provide valuable additional information in discerning new physics, and we identify prominent spectral features in b…
Rescattering following a neutrino-nucleus reaction changes the number, energy, and direction of detectable hadrons. In turn, this affects the selection and kinematic distributions of subsamples of neutrino events used for interaction or oscillation analysis. This technical note focuses on three forms of two-body rescattering. Elastic hadron+nucleus scattering primarily changes the direction of the hadron with very little energy transfer. Secondly, a hadron+nucleon quasi-elastic process leads to the knockout of a single struck nucleon, possibly with charge exchange between the two hadrons. Also…
After the first measurement of the coherent elastic neutrino nucleus scattering (CENNS) by the COHERENT Collaboration, it is expected that new experiments will confirm the observation. Such measurements will allow to put stronger constraints or discover new physics as well as to probe the Standard Model by measuring its parameters. This is the case of the weak mixing angle at low energies, which could be measured with an increased precision in future results of CENNS experiments using, for example, reactor antineutrinos. In this work we analyze the physics potential of different proposals for …
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…
The deployment of a low-noise 3 kg p-type point contact germanium detector at the Dresden-II power reactor, 8 meters from its 2.96 GW$_{th}$ core, is described. This location provides an unprecedented (anti)neutrino flux of 8.1$\times 10^{13} ~\bar{ν_{e}}/$cm$^{2}$s. When combined with the 0.2 keV$_{ee}$ detector threshold achieved, a first measurement of CE$ν$NS from a reactor source appears to be within reach. We report on the characterization and abatement of backgrounds during initial runs, deriving improved limits on extensions of the Standard Model involving a light vector mediator, from…
The cross section for coherent elastic neutrino-nucleus scattering (CE$ν$NS) depends on the response of the target nucleus to the external current, in the Standard Model (SM) mediated by the exchange of a $Z$ boson. This is typically subsumed into an object called the weak form factor of the nucleus. Here, we provide results for this form factor calculated using the large-scale nuclear shell model for a wide range of nuclei of relevance for current CE$ν$NS experiments, including cesium, iodine, argon, fluorine, sodium, germanium, and xenon. In addition, we provide the responses needed to captu…
In several extensions of the Standard Model of Particle Physics (SMPP), the neutrinos acquire electromagnetic properties such as the electric millicharge. Theoretical and experimental bounds have been reported in the literature for this parameter. In this work, we first carried out a statistical analysis by using data from reactor neutrino experiments, which include elastic neutrino-electron scattering (ENES) processes, in order to obtain both individual and combined limits on the neutrino electric millicharge (NEM). Then we performed a similar calculation to show a estimate of the sensitivity…
We present a new experimental method for measuring the process of Coherent Elastic Neutrino Nucleus Scattering (CENNS). This method uses a detector situated transverse to a high energy neutrino beam production target. This detector would be sensitive to the low energy neutrinos arising from pion decays-at-rest in the target. We discuss the physics motivation for making this measurement and outline the predicted backgrounds and sensitivities using this approach. We report a measurement of neutron backgrounds as found in an off-axis surface location of the Fermilab Booster Neutrino Beam (BNB) ta…
We present an updated analysis of the coherent neutrino-nucleus elastic scattering data of the COHERENT experiment taking into account the new quenching factor published recently in Phys. Rev. D100, 033003 (2019). Through a fit of the COHERENT time-integrated energy spectrum, we show that the new quenching factor leads to a better determination of the average rms radius of the neutron distributions of $^{133}\text{Cs}$ and $^{127}\text{I}$, while in combination with the atomic parity violation (APV) experimental results it allows to determine a data-driven APV measurement of the low-energy wea…
The physics reach of a low threshold (100 eV) scintillating argon bubble chamber sensitive to Coherent Elastic neutrino-Nucleus Scattering (CE$ν$NS) from reactor neutrinos is studied. The sensitivity to the weak mixing angle, neutrino magnetic moment, and a light $Z'$ gauge boson mediator are analyzed. A Monte Carlo simulation of the backgrounds is performed to assess their contribution to the signal. The analysis shows that world-leading sensitivities are achieved with a one-year exposure for a 10 kg chamber at 3 m from a 1 MW$_{th}$ research reactor or a 100 kg chamber at 30 m from a 2000 MW…
Probing Light Dark Particles in Neutrino Scattering Experiments
Southeast University（东南大学）；Tsung-Dao Lee Institute & School of Physics and Astronomy, Shanghai Jiao Tong University（李政道研究所与上海交通大学物理与天文学院）；Shanghai Jiao Tong University（上海交通大学）；Peking University（北京大学）
We calculate coherent elastic neutrino-nucleus scattering cross sections on spin-0 nuclei (e.g. $^{40}$Ar and $^{28}$Si) at energies below 100 MeV within the Standard Model and account for all effects of permille size. We provide a complete error budget including uncertainties at nuclear, nucleon, hadronic, and quark levels separately as well as perturbative error. Our calculation starts from the four-fermion effective field theory to explicitly separate heavy-particle mediated corrections (which are absorbed by Wilson coefficients) from light-particle contributions. Electrons and muons runnin…
Dark matter (DM) direct detection experiments are entering the multiple-ton era and will be sensitive to the coherent elastic neutrino nucleus scattering (CE$ν$NS) of solar neutrinos, enabling the possibility to explore contributions from new physics with light mediators at the low energy range. In this paper we consider light mediator models (scalar, vector and axial vector) and the corresponding contributions to the solar neutrino CE$ν$NS process. Motivated by the current status of new generation of DM direct detection experiments and the future plan, we study the sensitivity of light mediat…
Following our earlier work on the 3-dimensional effective velocity distribution of Galactic WIMPs (not only impinging on our detectors but also) scattering off target nuclei, in this paper, we demonstrate the normal and a "reverse" annual modulations of elastic WIMP-nucleus scattering signals, which could be observed in direct Dark Matter detection experiments. Our simulations show that, once the WIMP mass is as light as only a few tens GeV, the event number and the accumulated recoil energy of WIMP-induced scattering events off both of light and heavy target nuclei would indeed be maximal (mi…
We classify new physics signals in coherent elastic neutrino-nucleus scattering (CE$ν$NS) processes induced by $^8$B solar neutrinos in multi-ton xenon dark matter (DM) detectors. Our analysis focuses on vector and scalar interactions in the effective and light mediator limits after considering the constraints emerging from the recent COHERENT data and neutrino masses. In both cases we identify a region where measurements of the event spectrum alone suffice to establish whether the new physics signal is related with vector or scalar couplings. We identify as well a region where measurements of…
Last year the COHERENT collaboration was able to measure for the first time the Coherent Elastic Neutrino Nucleus Scattering (CE$ν$NS). Neutrinos within the right energy range can be produced in large quantities at accelerator facilities via pion Decay At Rest ($π$DAR) and used to measure CE$ν$NS. This new channel opens several, interesting possibilities: studying the CE$ν$NS spectrum it will be possible, for example, to search for Physics Beyond the Standard Model, looking for deviations from the predictions of the electroweak theory; it can also give important inputs for the understanding of…
Coherent Elastic Neutrino-Nucleus Scattering at the Japan Proton Accelerator Research Complex
University of Chicago（芝加哥大学）；Donostia International Physics Center（圣塞巴斯蒂安国际物理中心）；Ikerbasque, Basque Foundation for Science（伊克尔巴斯基，巴斯克科学基金会）；University of the Basque Country UPV/EHU（巴斯克地区大学）；Universitat de Barcelona（巴塞罗那大学）；Institució Catalana de Recerca i Estudis Avancats (ICREA)（加泰罗尼亚研究与高等学院）；Stony Brook University（石溪大学）
